AudioCircle
Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: Bumpy on 20 Nov 2018, 01:40 pm
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I have set myself a challenge to improve on these open baffle speakers assembled by Slawa of SW1X Audio Design
They are currently running with:
Tweeter: Saba Greencone 4" dipole
Midrange: Saba greencone 8" dipole
Base: Altec 416 8A 15" dipole
All drivers are vintage with alnico magnets, paper cones and mid 90s sensitivity. All are about 6-8 ohms.
At the moment they sound fantastic but I love a challenge :)
More to follow.
PS If ANYONE CAN TELL ME HOW TO STOP THIS SOFTWARE LAYING PICTURES ON THEIR SIDE I WILL BE MOST GRATEFUL.
(https://www.audiocircle.com/image.php?id=187081)
(https://www.audiocircle.com/image.php?id=187402)
(https://www.audiocircle.com/image.php?id=187403)
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Crossover? That's where the magic comes together.
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Crossover? That's where the magic comes together.
No resistors, all silver wired and parts like Audionote capacitors chosen by ear - and Slawa has excellent ears.
One of my main aims initially is to select mid range drivers with similar capacitance and sensitivity to the Saba Greencones. So for now, during evaluation the crossovers values should suffice.
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I now have a choice of two 8" drivers to evaluate against the Saba Greencones.
The first are vintage Supravox T215 RFT 64. These have similar characteristic to the Greencones. They are from France in the 60s and have the required Alnico magnets and paper cones, I have purposely avoided the model with wizzers.
Here is one shown alongside the Greencone. In terms of cost, the Greencones can be found below £100 in the UK and the Supravox are about £400 a pair. If it was a boxing competition the Supravox would take the prize, but its not :)
(https://www.audiocircle.com/image.php?id=187085)
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The second alternative 8" driver breaks the mould in that it is modern. But, it does have alnico magnet, papyrus cone, is 8ohms and about 95 sensitivity.
Its the SEAS X2 Exotic W8 - the model without wizzer. There are not a lot of reviews of its application in open baffles, so its a bit of an expensive gamble.
Here it is being put through some audio gymnastics whilst sill playing music. Dont ask me why the creator did it :)
https://www.youtube.com/watch?v=orC1QXULd5w (https://www.youtube.com/watch?v=orC1QXULd5w)
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The Saba Greencone hole in the front baffle will take neither of the new drivers and I am hesitant to hack it about until I know where I am going. At present, I plan a new circular baffle into which will be mounted the selected new driver. So as not to disturb the current tweeter (for now) the new baffle will be cut to clear it and allow it to breath.
Here is a paper template for the circular baffle. Sorry but the software here has again put the picture on its side. HELP ANYONE?
(https://www.audiocircle.com/image.php?id=187399)
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Am I talking to myself?
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Bumpy I have the same problem with photos being flipped on there side as well, rather frustrating. I rephotograph using an Android app on my tablet and that seems to help.
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My first experiment is not to cut the existing piano black front baffle, but to place the new circular baffle on the floor. This presents the greatest challenge to the driver.
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Sorry, I cant post pictures now as I get error messages and it locks me out :scratch:
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For technical issues with the site, better to open a thread in Requests for Help or Bug Reports.
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In terms of improvement, have you considered going active?
PartsExpress sells an affordable DSP these days, and being able to adjust bass vs mids vs treble easily can be a great way forward.
I ran active Xover in my own OB explorations for a long time. I could not have done it without biamping the mains and subs.
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For technical issues with the site, better to open a thread in Requests for Help or Bug Reports.
When I get locked out, I really get LOCKED OUT and cant even send a bugs report.
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In terms of improvement, have you considered going active?
PartsExpress sells an affordable DSP these days, and being able to adjust bass vs mids vs treble easily can be a great way forward.
I ran active Xover in my own OB explorations for a long time. I could not have done it without biamping the mains and subs.
I have played with DSP in my days with a TACT. Its not for me as its just more digital processing of the music, which I try to avoid.
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Tact has been around a long time, some of their 2 channel DSP tech is from around 18 years ago.
I respect that you're not interested, but even the new $200 DSP from Dayton can do a remarkable number of things to help crossover, time alignment etc.
I would not want to try to integrate drivers without an external crossover (ideally in the digital domain).
Looks like you do have access to some great drivers!
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Thanks, but most changes to digital over the years have involved yet more processing and filters. It all robs the music of its magic. But I agree some people seem to enjoy it :)
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http://lampizator.eu/SPEAKERS/PROJECTS/P17/Endorphine%20from%20Kingston%20Kitchen.html
Hello Bumpy,
Have a look at Lampiztors P17 loudspeaker
I am sure you will recognize it
Crossover is also attached
I personally like no bandpass filter on the fullrange
It makes the magic disappear
1 Cap on helper tweeter is ok
Helper woofer Altec is to weak to give sufficient bass with a 6 or 12 db lo-pass filter
Enjoy...
Ronny
Enjoy...
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http://lampizator.eu/SPEAKERS/PROJECTS/P17/Endorphine%20from%20Kingston%20Kitchen.html
Hello Bumpy,
Have a look at Lampiztors P17 loudspeaker
I am sure you will recognize it
Crossover is also attached
I personally like no bandpass filter on the fullrange
It makes the magic disappear
1 Cap on helper tweeter is ok
Helper woofer Altec is to weak to give sufficient bass with a 6 or 12 db lo-pass filter
Enjoy...
Ronny
Enjoy...
Thanks for getting involved
Yes my speakers were put together by Slawa at SW1X. They started life as a clones of the p17s, but Slawa improved upon the design and components. The crossovers at present work fine and give a complete spectrum of frequencies. Despite the predicted lack of bass from the Altec 416 8A 15" dipole, I find with the slight side wings it is perfectly fine for me.
I haven't interrogated the crossovers fully, but believe the Greencone is 'managed' at both the low and high frequencies. My initial aim is not to mess with the crossovers until the selected midrange is bedded in. But I note that the midrange can operate with no bandpass filters. I suspect my selected alternatives can do this better than the Greencones, which can become a bit ragged at its extremes.
As far as I know, the crossovers are at about 650 Hz and 6.5Kz. I am no expert but that looks a pretty wide mid range :)
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I am posting a picture of smaller size and it seems to work.
Rather than cut into my nice piano black baffles just yet I will evaluate the drivers in the new circular baffles propped up on the floor. This is a real stress test for SQ. The wires were un-soldered from the Greencones and re-soldered onto the new drivers. No other mods were made.
(https://www.audiocircle.com/image.php?id=187398)
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Observations on the vintage Supravox T215 RFT 64
As its vintage there is no need to run it in, and it demonstrates very similar characteristics to the Greencones but is better in all aspects. It integrates well into the system, has more 'drive', is more dynamic, more transparent and would prove a big improvement to the Saba Greencones. If there was no alternative I would be very happy here.
(https://img4.annuncicdn.it/48/92/4892d670e4a8bb4110ed7cdcce132147_orig.jpg)
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Observations on the SEAS X2 Exotic W8
These are new drivers and may well take some running in.
First impression is that they are SMOOTH. But the sound stage is tiny, barely reaching my kneecaps. Two hours later the sound stage is halfway up the wall and ten hours later it fills the entire wall around the speakers - amazing. The sound quality remains smooth (refined) and is now a step up again on both of the previous drivers. After twenty hours they are my drivers of choice.
I phoned the supplier to congratulate him on great drivers. He only had one comment "just twenty hours, they take up to two hundred hours to run in"
He is probably right as looking at the driver whilst it is playing I have yet to see it move, compared to the punishment it was taking in the video posted earlier in this thread :)
(https://www.madisoundspeakerstore.com/images/products/exotic-w8-08.jpg)
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Observations on the SEAS X2 Exotic W8
These are new drivers and may well take some running in.
First impression is that they are SMOOTH. But the sound stage is tiny, barely reaching my kneecaps. Two hours later the sound stage is halfway up the wall and ten hours later it fills the entire wall around the speakers - amazing. The sound quality remains smooth (refined) and is now a step up again on both of the previous drivers. After twenty hours they are my drivers of choice.
I phoned the supplier to congratulate him on great drivers. He only had one comment "just twenty hours, they take up to two hundred hours to run in"
He is probably right as looking at the driver whilst it is playing I have yet to see it move, compared to the punishment it was taking in the video posted earlier in this thread :)
You could get the same result with the inexpensive Visaton B200 in OB or in a 100L sealed box or 200L to more bass.
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You could get the same result with the inexpensive Visaton B200 in OB or in a 100L sealed box or 200L to more bass.
Wow it's amazing that you can hear the performance of my system from your house.
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Wow it's amazing that you can hear the performance of my system from your house.
The performance of these drivers are public know.
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The performance of these drivers are public know.
If you say so.
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If you want to see it move, feed it some power at low frequencies. The earlier video looks like someone trying to do some mechanical break-in at a few Hz, I don't they're actually playing that music.
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If you want to see it move, feed it some power at low frequencies. The earlier video looks like someone trying to do some mechanical break-in at a few Hz, I don't they're actually playing that music.
I'm not sure I have a need to see it move :). I am quite happy to run it in without stressing it. If you draw the analogy with a car, the running in period should be prolonged and gentle, not thrashing it straight out the showroom. :o
I am enjoying listening to the music quality as it evolves.
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I am not gifted at electronics and would appreciate a bit of help in understanding the crossovers used in the Endorphin p17
All I have grasped to date is that the tweeter has a high pass filter (Butterworth 1st order?). But what are the others for. It would be really nice to have the crossovers 'named' so I can calculate the effects of changing component values. Like Lampizator insists, these are crossovers without resistors.
(https://www.audiocircle.com/image.php?id=187407)
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I was fortunate in that selecting the SEAS driver meant it could be bolted into my baffle with only a bit of carpentry. Here it is in location and running in.
(https://www.audiocircle.com/image.php?id=187409)
This gives me time to think about crossover and tweeter changes
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:popcorn:
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This image show a relatively simple 3way xover only with caps and inductors:
For tweeter: 4 micro Farad capacitor
For mid: 80 micro Farad cap and a 0,39 mili Henry inductor
For woofer: 68 micro Farad cap and the usual big 4,7miliHenry inductor for 270Hz first order cut.
What sound effect will occur change the parts electric value I cant say, you should ask an expert as our AC member Jeff at Sonic Craft Circle:
You can reach Jeff here>
https://www.audiocircle.com/index.php?board=201
(https://www.audiocircle.com/image.php?id=187407)
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Thanks for the advice. I have posted there. :thumb:
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Moving on to tweeters.
My next step is to double up on the Saba Greencone tweeters. The additional one will be round the back, firing up, down, sideways and in and out of phase. The consistent aim is to keep voice coil centres aligned and hopefully because of the wavelengths involved, within about 3" of the mid range voice coil.
Additional Greencone tweeters are selected initially because:
1. Similar sensitivity to main tweeters (95dB)
2. Alnico magnet and thin paper cone to give similar signature to other drivers
3. I have them in the cupboard.
I am contemplating pairing up the SEAS midrange with a forward facing SEAS Exotic tweeter which is a match made in heaven (SEAS!). BUT it is expensive and mono pole and I haven't yet resolved whether that is a negative thing.
(https://www.audiocircle.com/image.php?id=187468)
There is some history of pairing the SEAS exotic drivers in the Salk exotica speaker albeit a different design but it is extremely well reviewed.
(http://www.salksound.com/gallery/Exotica%20Monitors/a.jpg)
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3. I have them in the cupboard.
Ha, I like that :thumb:
For the price of those Seas tweeters you could get Mundorf AMT dipoles, or Aurum Cantus AST2560 at less than half the price. Either can be "converted" to monopole by putting a rear chamber on it... the AST2560 starts that way anyway, sort of.
[Edit] The caveat with those might be that they won't like first order crossovers.
[Edit Edit] Actually the Mundorf spec sheets do give a recommended crossover frequency for first order so maybe they're OK after all.
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Ha, I like that :thumb:
For the price of those Seas tweeters you could get Mundorf AMT dipoles, or Aurum Cantus AST2560 at less than half the price. Either can be "converted" to monopole by putting a rear chamber on it... the AST2560 starts that way anyway, sort of.
[Edit] The caveat with those might be that they won't like first order crossovers.
[Edit Edit] Actually the Mundorf spec sheets do give a recommended crossover frequency for first order so maybe they're OK after all.
I am sorry but I don't think that 'diaphragm' tweeters are for me. I am trying to keep the paper cone, alnico magnet sound and not go 'ultra hi fi'.
I agree with you John the Exotic tweeters are really expensive. I suspect part of their worth is that the play down to lower frequencies as they are certainly no supertweeters. This is not a quality I require.
https://www.falconacoustics.co.uk/downloads/Seas/x3-06_datasheet.pdf (https://www.falconacoustics.co.uk/downloads/Seas/x3-06_datasheet.pdf)
Incidentally, how does one know which drivers don't like 1st Order crossovers?
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Here is a picture from yesterdays experiments. The tweeter was secured with bungee ropes. :) Sorry, the pictures laid itself down AGAIN.
There was a noticeable improvement in ambience without a loss of focus, so it shows promise.
The most successful positions were rear firing directly behind the existing dipole (out of phase) and upward firing from the top of the baffle. I have formed the opinion that a dipole is not needed in this situation, so I am on the look out for a cheap soft domed mono pole tweeter of 95dB with extended top end to show proof of concept.
(https://www.audiocircle.com/image.php?id=187531)
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The most successful positions were rear firing directly behind the existing dipole (out of phase) and upward firing from the top of the baffle.
You can also try upfiring the tweeter from behind the baffle, about a foot away from the baffle wall, but also about a foot or two below the top of the baffle. In this configuration the tweeter should be wired with reverse polarity to that of the baffle mounted driver(s). This sometimes works well from a reflection standpoint, but is also contingent on the tweeter's radiation pattern, crossover frequency, and ceiling height. Lots of variables when trying to harness reflected sound in a non destructive way.
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You can also try upfiring the tweeter from behind the baffle, about a foot away from the baffle wall, but also about a foot or two below the top of the baffle. In this configuration the tweeter should be wired with reverse polarity to that of the baffle mounted driver(s). This sometimes works well from a reflection standpoint, but is also contingent on the tweeter's radiation pattern, crossover frequency, and ceiling height. Lots of variables when trying to harness reflected sound in a non destructive way.
:thumb:
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I am in the process of ordering some Faital Pro HF 102 drivers to serve as ambient tweeters. These are compression speakers and with their attached horn can reach 107 dB efficiency. Minus the horn they come in about 95 dB and at 8 ohms they fit the bill well.
When they arrive I will once again try the experiments to ideally locate them. I am optimistic that in this application they will do a better job than the dipoles. Where the rear signal just serves to 'mess with' the other drivers.
Thanks to Matevana for his help in this. :thumb:
(https://faitalpro.com/products/files/HF102/HF102_photo.jpg)
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I'd really like to hear the Seas X2 Exotics one day. I've read some really positive listening impressions. I did get to hear the Seas FA22RCZ in a Voigt pipe installation and it wasn't too shabby. I imagine the Exotics are in a whole 'nuther league.
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This is an idea I hold in my mind for future reference. Anyone tried anything like this?
(https://scontent-lht6-1.xx.fbcdn.net/v/t1.0-0/q82/s261x260/33748791_10208899442001746_8092768019836567552_n.jpg?_nc_cat=101&_nc_ht=scontent-lht6-1.xx&oh=ac8aa37d1c3a4a9d7ea5b2bbf9c8e6e1&oe=5C9D6A75)
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I have heard the Mirage line of omni directional speakers that use a tweeter positioned over the woofer with a ball like that directly above the tweeter.
They did a great job of a diffuse soundstage in my room. Good friend of mine owns them.
(https://hometheaterhifi.com/volume_10_2/images/mirage-omni-speakers-omniguide.jpg)
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The German loudspeaker company Duevel was one of the first to promote this idea with their Planets speaker:
(https://www.audiocircle.com/image.php?id=187811)
They also have some pretty interesting ways to address omnidirectional dispersion. They use high efficiency pro sound compression drivers for the mids/highs in both up and down firing configurations.
(https://www.audiocircle.com/image.php?id=187812)
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I was sitting listening to my open baffles last night reflecting that despite playing the music at a reasonable volume I cant see the mid range drivers cone moving at all.
I can feel the vibrations in the driver's cone, but visually you would not know it was on. Its a new driver and is reckoned to take up to 200 hours to run in properly in a box where I guess the cone and suspension will move about more. I know there are ways to run the drivers in more rapidly buy I am enjoying the ride. :)
Has anyone else noticed this phenomenon?
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Most vintage FR drivers have XMAX 1mm, the Audio Nirvanas being a old recipe drivers also have Xmax around 1mm, some has less, same as Alpair, but I already see Xmax around 3mm in FR usually in pro audio.
If it have a large Xmax it can be a woofer or midrange.
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Most vintage FR drivers have XMAX 1mm, the Audio Nirvanas being a old recipe drivers also have Xmax around 1mm, some has less, same as Alpair, but I already see Xmax around 3mm in FR usually in pro audio.
If it have a large Xmax it can be a woofer or midrange.
These SEAS Exotic 8" have a 6mm linear p-p and I'm just impressed that they make such lovely music without moving :)
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The Visaton b200's I used for a decade on OB had a similar PP XMAX (~6-7mm) and the only time I really saw them move much was when they were asked to play below 100Hz.
Where do you Xover your SEAS drivers? Lovely pieces by the way.
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The Visaton b200's I used for a decade on OB had a similar PP XMAX (~6-7mm) and the only time I really saw them move much was when they were asked to play below 100Hz.
Where do you Xover your SEAS drivers? Lovely pieces by the way.
Trying to run it as wide as possible so crossing over to the Altec 416 15" bass at 6-700 Hz and to the Saba Greencone dipole tweeter at 6-7 Khz.
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Well, driver excursion increases by 4 times every time you halve the frequency, or conversely decreases by 4 times for each doubling of frequency. So for example at 640 Hz you would have 1/64th as much excursion as you would at 80.
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Well, driver excursion increases by 4 times every time you halve the frequency, or conversely decreases by 4 times for each doubling of frequency. So for example at 640 Hz you would have 1/64th as much excursion as you would at 80.
Now there's something I didn't know. :D
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These SEAS Exotic 8" have a 6mm linear p-p and I'm just impressed that they make such lovely music without moving :)
Please note these Seas FR dont follow the vintage old school which use accordion, conex or Fabric cloth surrounds, they use rubber as AER so they offer a different sound quality.
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Its a new driver and is reckoned to take up to 200 hours to run in properly in a box where I guess the cone and suspension will move about more.
I've found that drivers move around more in OB, followed by a ported enclosure, and lastly a sealed enclosure. Probably b/c there is no 'slug of air' (spring effect) that acoustically dampens the driver, something that a boxed enclosure might otherwise provide. The high-ish crossover would explain why you see no real movement, as John mentions.
Have you listened to the Seas w/o a crossover?
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Have you listened to the Seas w/o a crossover?
Nope, but that's something I plan to try now it is beginning to run in.
Firstly running the SEAS full range on its own.
Secondly adding just the Saba tweeter to judge the impact - remember I specified the SEAS has no whizzer.
Thirdly adding just the Altec 15"
I should learn a lot from those experiments :thumb:
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Cool! I'd like to hear your listening impressions.
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SEAS Exotic on its own
Great speaker and great sound with no nasties or raggedness but boy did I miss the frequency extremes. Ultimately after an evenings listening I decided I could not live without the other frequencies any longer, nothing underpinning the presentation, a lack of air, and reduced imaging.
But on the plus side I now have a good idea of the frequencies that a good 8" driver is capable of in this environment and why 3 ways make sense :)
Next because, its easy to do, I will play just the bass and tweeter together to get a measure of the 'hole in the middle'
Of note, is that the SEAS driver still did not move to any great extent. Not sure what that is telling me, perhaps its just the way it is, or perhaps its a long way from being run in when I guess the suspension will breath more easily.
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Good to know. I forgot you are working with the X2, which is sort of the woofer version of the full range X1. It's always good to listen to drivers on their own, so you can better appreciate what you are working with.
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Good to know. I forgot you are working with the X2, which is sort of the woofer version of the full range X1. It's always good to listen to drivers on their own, so you can better appreciate what you are working with.
Yes having owned various Lowthers and listened to other whizzer drivers. I did not want to go down that route. If the HFs are not to your liking you have to dump the whole thing, also the whizzer has moving mass and must influence the midrange a bit.
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Could a moderator please merge this thread with my other thread entitled "My tactics for improving vintage 3 way open baffles"
Just like my office desk I have stuff everywhere :)
Thanks for the merge :thumb:
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Experiment to play music with the mid range driver disconnected. Crossovers at 650Hz and 6.5KHz
Never tried this before so I was not sure what I really expected to get from this, but I guess my real intention was to see how much 'room' was left in the centre frequencies to accommodate the mid range driver. Attached is a You Tube video of the resultant sound played at typical listening volume. Here are my conclusions and I would be interested to hear what you think.
1. The female voices seem to push a long way down from the tweeter. (Saba 4")
2. The male voices seem to push a long way up from the bass driver (Altec 416 15")
3. The bass driver seems articulate and musical but missing a bit of impact - perhaps an open box on the back might be an idea.
https://www.youtube.com/watch?v=LQzmF8I8TPo&feature=youtu.be (https://www.youtube.com/watch?v=LQzmF8I8TPo&feature=youtu.be)
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Great experiment, the resulting are impressing, I would like to put a 10 or 12 inches for midrange this this OB speaker to see the results.
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Also, the sound quality is inversely proportional to the amount of Jameson Irish Whiskey. Now I feel compelled to subscribe to your YouTube channel. ;)
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Also, the sound quality is inversely proportional to the amount of Jameson Irish Whiskey. Now I feel compelled to subscribe to your YouTube channel. ;)
I know that YouTube has its limitations but I'm not happy with the SQ recorder on my DSLR. If the New Year Sales are kind I am going to treat myself to something like this.
(https://thumbs4.ebaystatic.com/d/l225/m/mRUorwpJUu43qLOG1B3lwCQ.jpg)
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Still using my DSLR camera and still with the mid range driver disconnected I decided to explore the effect of installing a very crude U frame aka a box with no back to the rear of the bass driver. The aim is to help alleviate cancellation of the front signal by the rear at these long wavelengths. I have uploaded two videos of quite different music but believe there is a major improvement.
(https://www.audiocircle.com/image.php?id=188367)
https://youtu.be/6Ji4yqjtkJ4 (https://youtu.be/6Ji4yqjtkJ4)
https://youtu.be/BV53qw-roBw (https://youtu.be/BV53qw-roBw)
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Hi bumpy:
Here are some impressions I have gotten after listening to your videos via YouTube. I used a pair of iems driven by a chord mojo. I did recognize the sonic signature of the alnico drivers you have had but perhaps they were the tracks/music that was reproduced but to my ear I guess the sound was somewhat midrange based...upper midrange. The only alnico experience I have had is through my 8” Fostex F200A drivers in a MLTL cabinet along with correction. Furthermore, my amplifiers are all class A/B solid state that varies from op chip designs to marantz HT receivers.
As I stated before in another post, I felt that the midland was too prominent, at least to my ears. The maddening thing about sound comparisons is that not everyone uses the same tracks when comparing. What floats my boat musically is entirely different from
What other people use. One thing is for sure...I have found my new sonic standard being the reviews that the girl who run earspace vía YouTube run. She uses the same tracks and also vinyl with all the systems that she review.
So, as I mentioned before, I feel that your system, to me sounds a little thick. Maybe there is a aural different that you might be able to hear there because you are familiar to the tracks but with my imprecise ears, they sound a little thick. Perhaps the crossover especially in the upper midrange can be varied?
Btw, congratulations on what I see is a very well thought out system.
Looking forward hearing more of your experiments and more videos. From
NYC.
Paul
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Thanks Bemopti for taking the trouble to comment. The music you hear from my system is part of an experiment to determine the contribution from the tweeter, but primarily the bass driver.
The mid range driver is completely disconnected and yes to me it is also very "thick" because of the missing frequencies between 600Hz and 6.5Khz :) My main aim here is to determine how much contribution the bass and HF units have on the mid range - hence playing tracks with male and female vocals
My main conclusion at present is that the improvised (bodged) U frame has improved the impact and clarity of the bass, but there is now a faint echo to the bass. I am guessing the box is too deep or that the low crossover needs to be lowered from 600Hz.
I am happy with either of these conclusions particularly lowering the crossover to say about 200Hz as my new SEAS Exotic W8 midranger is fully capable of playing down to that, whereas the original builder of the OBs may have been working around the lower limitations of the 8" Greencones
(https://www.audiocircle.com/image.php?id=188445)
Any other comments critical or not are most welcome at this stage.
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Have you considered learning to measure the frequency response of your speakers?
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Have you considered learning to measure the frequency response of your speakers?
I have, but having read a bit about it, it makes my brain hurt. For a one off project it seems very complex and expensive.
If I had a wish list this would be it
1. A CD track to play white noise having all frequencies equal in volume.
2. A bit of simple software on my computer to listen and display the frequencies it is listening to.
I would accept non professional accuracy and would be happy with a non sophisticated graph of what was occurring. After that I tune by ear.
Seems too simple to be true. ☺️☺️☺️
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Gosh, when I was reading your posts I did read that you were experimenting to see woofer frequency response. Duh. Anyway, waiting to hear the findings of your experiments. Can you make a list and brief profile of your amplification pieces as well as your sources? Thanks! :thumb:
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Gosh, when I was reading your posts I did read that you were experimenting to see woofer frequency response. Duh. Anyway, waiting to hear the findings of your experiments. Can you make a list and brief profile of your amplification pieces as well as your sources? Thanks! :thumb:
Here you go. :)
Bottom right. SW1X Universal Music Server UMS I Signature with its dedicated valve Power Supply Unit PSU I Signature
Bottom left. SW1X USB I Signature - valve (to convert USB to spdif)
Top left. SW1X DAC II Special - valve
Top right. Transcription Audio single ended, 211 triode, integrated - valve
SW1X Open Baffle Speakers containing both vintage and modern alnico drivers - Grundig tweeters, SEAS exotic W8 midrange and Altec VOTT 416 bass. All silver wired.
Silver mains cables, interconnects and speaker cables by SW1X
http://sw1xad.co.uk/ (http://sw1xad.co.uk/)
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I would accept non professional accuracy and would be happy with a non sophisticated graph of what was occurring. After that I tune by ear.
If you have a smartphone you could look into apps for it, there's a bunch of them and no doubt some are free, they aren't super accurate but probably good enough to gain some insights.
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Eagerly await for some more mods and accompanying videos. While many people have described in text what they have done in terms of electronics and acoustics, it is a different thing and much better, to be able to hear the results through a video. :thumb:
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If you have a smartphone you could look into apps for it, there's a bunch of them and no doubt some are free, they aren't super accurate but probably good enough to gain some insights.
I’m a bit of a Luddite at these things, but did get a new iPad for Xmas. I will have a search, thanks.
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This is where I have ended up with the bass. Results are a bit too subtle for you tube.
1. There is a recommendation to use a shallow U baffle behind the bass driver - no more than 8" deep to avoid setting up an 'echo chamber'. This added a bit of focus to the bass but I could not perceive it being any deeper. This may be because my baffles already have slanting sides.
2. Deep U frame (see previous photo). This did bring out the bass but sure enough there was an echo, particularly on deep male voices.
3. Deep U baffle, without top. This enhanced the bass and removed the echo. I guess this has just created extended front baffles, but is short enough to avoid messing with the mid and HF. For the time being I will pretty up the speakers and live with this.
So that's the midrange and bass sorted. On now to the HF with the installation of 'super tweeters'
Sorry, the software here has laid it down again.
(https://www.audiocircle.com/image.php?id=188639)
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Temporary baffles in place, using offcuts from an old cupboard. Time to think about something posher later.
(https://www.audiocircle.com/image.php?id=188885)
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Had a bit of a set back today when I took my new Pro Faital HF 102 tweeters out of their boxes to have a play. As you can see they are different versions.
Apparently one is old stock and will be replaced when more arrive in store.
In the meantime the SEAS midrange drivers and my new 211 valves can continue to run in. :thumb:
(https://www.audiocircle.com/image.php?id=188900)
(https://www.audiocircle.com/image.php?id=188901)
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Interesting. I have a pair of the lower version with the built-in o-ring. Not sure whether I have the old or new, but I continue to like them a lot. They sound like a quality dome tweeter with the output of a compression driver. They are also very small and light compared to typical pro sound horn drivers.
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Interesting. Which one is the newer one?
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The gasket version is the newer one.
I am convinced they will sound the same, but if the experiment is not as I hope then I will need to resell them and at that point it will become an issue. :cry:
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Positioning
Due to space restrictions my speakers baffles have always been about 900 mm from the wall behind. This has always been fine for SQ.
Now with the extended 'side' baffles, the most rear pont of the speakers sits just 35mm from the wall. This didn't seem good, so I moved the whole speakers forwards to make this gap 60mm and have the front baffles now sitting 1020mm from the wall.
This has made a wonderful improvement mainly to imaging, which is now pin sharp, but also to perceived bass. I listen near field and now have the biggest headphones imaginable. This listening position puts critical strain on the quality of the system, which it passes with glory.
The only problem will be the wife who has already remarked that the speakers seem to creep out further into the room on their own. For the sake of matrimonial harmony I am going to make the speakers easily movable using either wheels or gliders. ATM I favour PTFE gliders as they do not leave such a big gap under the baffles.
Picture is of the speakers in their compromised position
(https://www.audiocircle.com/image.php?id=188885)
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Over a decade ago there was some discussion that stuffing even open rear cavities behind the bass driver could give a forward facing bass gain of up to 6db. What is the current thinking on this?
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John K did some research on a damped (stuffed) U frame vs open U Frame: http://www.musicanddesign.com/u_frame.html (http://www.musicanddesign.com/u_frame.html)
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John K did some research on a damped (stuffed) U frame vs open U Frame: http://www.musicanddesign.com/u_frame.html (http://www.musicanddesign.com/u_frame.html)
Thanks Matevana, some good reading there together with the link to Nao.
I did a VERY crude experiment yesterday evening using fluffy pillows to stuff the structure behind the bass driver. I didn't notice a great deal of improvement in the bass and the lovely imaging in the lower frequencies was compromised, so not a lot of encouragement there :(
If I was asked why, I would guess that the bass is affected less if you are listening near field and that with a bass crossover of 650 Hz the stuffing would be impacting on the lower midranges.
I will still keep the idea in mind.
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I agree with you. I haven't been successful in properly damping a U/H frame enclosure. John is a smart guy and I don't doubt his hard work. I just haven't been able to achieve positive results in my attempts.
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I stick (frost king) foam directly on to the (driver) magnet.
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Is that just to stop reflections from the magnet, or is there more to it?
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Just thinking aloud.
I keep asking myself why I don't speed up the break-in process for my new SEAS Exotic W8 drivers, by playing them face to face out of phase at high volume etc. The reality is, the cones have a linear travel range of 6mm and a max travel range of 22mm and I have never actually seen the cones move at all in their suspension. So, the break-in process is going to take a few hundred hours (similar to Lowthers).
I have decided that for me personally its like having the most beautiful woman in the World doing a strip tease in your room. It's much more fun watching the whole performance evolve rather than leaving the room and closing the door.
I guess this You Tube video (that I have posted before) is the opposite philosophy.
https://www.youtube.com/watch?v=orC1QXULd5w (https://www.youtube.com/watch?v=orC1QXULd5w)
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Yesterday I disconnected the bass drivers and ran the SEAS Exotic W8 full range in the bass. This confirmed
1. That the SEAS drivers are really wonderful and quite capable of running much lower than the Saba Greencones they replaced.
2. The Altec 416B alnico bass drivers are crossed over way too high for the SEAS drivers and are trampling on some of the magic.
Current crossover I believe is about 650Hz and SEAS recommend a crossover for their driver of 100Hz, hence the clash.
My first task this evening is to reconnect, then reverse the polarity of the bass driver to see what effect that has.
(https://www.audiocircle.com/image.php?id=187407)
As I understand it, the low pass filter on the Altec is a 2nd order Butterworth. My inductors are Jantzen C Cores and capacitors are Audionote Kaiseis so a bit too expensive to be experimenting by substitution :(
Can anyone recommend an on line calculator so I can select values for this Butterworth crossover or alternative components I can use to experiment. I am warming to the idea of a calibrated measuring microphone. :)
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Most use the same mathematical formulas for a given type/order, so it's really a question of who's interface you prefer to work with. I tend to like the ERSE site: http://www.erseaudio.com/CrossoverCalculators (http://www.erseaudio.com/CrossoverCalculators)
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Thanks Matevana, you wont believe how long I searched for such a calculator :duh:
In my low pass filter my actual inductors are 3.9mH and caps are 100uF.
The calculator suggests that to get a crossover value of 500 Hz one should use inductors of 3.6mH and caps of 28uF. As the caps are three times the value of those recommended would you know if this pushes up or lowers the crossover point.
Also could could you recommend 'cheapish' inductors and capacitors that I could experiment with before switching to expensive ones to finalise the low pass.
Thanks for your continued help.
PS reversing the polarity of the bass drivers made no significant difference.
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A higher value capacitor in a 2nd order low pass filter, will increase the rate of attenuation of any high frequencies above the cut off point (roughly 500 Hz in this case). The crossover point is largely determined by the inductor in this circuit; the way in which it rolls-off is influenced by the cap.
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A higher value capacitor in a 2nd order low pass filter, will increase the rate of attenuation of any high frequencies above the cut off point (roughly 500 Hz in this case). The crossover point is largely determined by the inductor in this circuit; the way in which it rolls-off is influenced by the cap.
Thanks Matevana, spot on reply. :)
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My midrange and tweeters are working brilliantly. The big challenge that remains is to seamlessly integrate the bass drivers using low pass filters.
I hope to leave myself plenty of flexibility and would like to be able to adjust not only the crossover point, but also the order of slope. Quality components for experiments are VERY expensive and I appreciate that the more complex the crossover the more it is likely to lower sensitivity of that driver which is not good.
This is leading me to think about powering the bass drivers separately with DSP amplifer such as the MiniDSP PWR ICE125. Has anyone gone down that route?
Although not open baffles, I am drawing inspiration from the Salk Exotica 3 speakers which also use the SEAS Exotic midrange and supplement it with servo woofers. This is what they say
SERVO WOOFERS
In order to maintain high sensitivity and provide bass response down to 20Hz, we've incorporated a servo-controlled woofer section into the equation. So your amplifier only supplies power to the midrange and tweeter section of this speaker.
Those speakers of theirs retail about $13000 and have an excellent reputation. :)
http://www.salksound.com/model.php?model=Exotica+3 (http://www.salksound.com/model.php?model=Exotica+3)
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http://www.rythmikaudio.com/F8.html (http://www.rythmikaudio.com/F8.html)
Essentially this is the low end of the speakers. You can also buy the drivers and the amp to put in your own enclosure if you would like. There are also open baffle versions available.
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Just a bit of an update.
I have the 15" bass unit disconnected for now until I work out a low pass filter.
The tweeter has its existing capacitor to protect it and the SEAS Exotic W8 is running full range (both top and bottom) - no capacitors, no inductors, just silver wire to connect it. This is by far the best it has sounded.
Essentially this is now a two way open baffle and the best it has ever been. I could live with it for a few months if I have to. The vintage Tweeter and Exotic W8 work beautifully together so looks like I fluked that.
The next job is to integrate the open baffle bass driver into the system, just like one would a subwoofer. As there is no high pass filter imposing a defined slope on the midrange driver (eg Butterworth 12dB), integration is that bit more difficult and continues to insist I buy a calibrated microphone and do some measurements.
Maximum flexibility seems to be the order of the day so a DSP amp is attractive, but it needs a high level input as the system volume will be controlled by the 211 triode integrated. This is very common for subwoofers, but not DSP :roll:
Here is a spec for what I am looking for.
1. High level inputs from speaker terminals of main amp (therefore no impact whatsoever on the existing two way drivers)
2. DSP for maximum flexibility.
3. Amplification should be best SQ but probably can cope with 50 W/channel minimum. (Class A/B or D Class?).
4. No thump at turn on.
Will try and post a YouTube video later though I dont yet have a good microphone.
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I am firming up on the way to go now. I will parallel up the signal to the speakers. Part will go normally to the OB mid and tweeter and part will go to a 'speaker to line level' converter to give a signal that will be fed to a Minidsp 2x4 for setting up and optimising the low pass filter. Hence to a highly modified Rotel amp and on to the bass drivers.
I have just bought the Rotel that has been modified and it is coupled with a cheap Marantz CD player that I saved from a skip. This combination is being used to run in the SEAS drivers (currently 140 hrs).
I was so impressed with the SQ that I took a video. Remember no bass drivers and just the cheap combo feeding the OBs. Shame about my camera which seems to add a bit of an echo, but then I'm buying the MiniDSP UMIK-1 which I'm hoping will do a better job.
https://youtu.be/At48Yh4EnHI (https://youtu.be/At48Yh4EnHI)
And another with same conditions.
https://youtu.be/gVeZeEeRBzM (https://youtu.be/gVeZeEeRBzM)
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Here is a spec for what I am looking for.
1. High level inputs from speaker terminals of main amp (therefore no impact whatsoever on the existing two way drivers)
2. DSP for maximum flexibility.
3. Amplification should be best SQ but probably can cope with 50 W/channel minimum. (Class A/B or D Class?).
4. No thump at turn on.
It would be nice to find both high level inputs and DSP in the same unit, but that may prove difficult. I've had decent results with the Yung plate amps. Most have both speaker level and line level inputs, but the lowpass uses an analog signal processor and they obviously don't do biquads, pre/post eq, etc. They are dead quiet when they turn on, but oddly there is a bit of a thump when they power-off, about 20 minutes after the last signal.
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I wonder if the Dayton DSP-408 could work?
It is not an amp, but will do all the other things you're looking for. You could use a pro amp for the woofers.
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I wonder if the Dayton DSP-408 could work?
Thanks for the recommendation . I will have a look at it. My experience on the MiniDSP site forum is not good - its typical of many HI Fi forum and may threaten my buying from them.
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A friend leant me a signal generator this evening.
The SEAS Exotic has worthwhile output down to 100hz and thankfully is where I planned to cross it over.
The 15” Altecs with the existing low pass filters have worthwhile output up to 3.5khz. This is far too much overlap and the reason I will employ DSP with separate amp for the bass.
Just thinking out loud really, but the Altecs were supposed to be crossing at 6-700 hz. Useful output at 3.5khz seems rather odd. What do you think?
For completeness it’s low pass filter is currently a 3.9mH inductor in series and a 100uF capacitor in series.
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A friend leant me a signal generator this evening.
The SEAS Exotic has worthwhile output down to 100hz and thankfully is where I planned to cross it over.
The 15” Altecs with the existing low pass filters have worthwhile output up to 3.5khz. This is far too much overlap and the reason I will employ DSP with separate amp for the bass.
Just thinking out loud really, but the Altecs were supposed to be crossing at 6-700 hz. Useful output at 3.5khz seems rather odd. What do you think?
For completeness it’s low pass filter is currently a 3.9mH inductor in series and a 100uF capacitor in series.
I sometimes feel I am talking to myself, but at least it keeps a record here :)
I have slept on it and this is my theory for the high frequencies heard from the bass driver.
The bass driver in OB has a severe roll off at low frequencies due to cancellations around the baffle. For this reason to get a balanced output, the bass driver (in my OBs) is more sensitive than the mid range driver (its about 98-100dB) and delivers a higher volume than one can hear at the seating position. But as one gets towards 1Khz the roll off effect from the baffle is severely reduced so the high frequency output from the bass driver has a higher 'volume' and can be heard.
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Lets look at the Bass driver amps etc. which will be run independently of the mid and tweeter.
I am taking a separate output from the speaker terminals of my power amp. It's difficult to get a real fix on the voltages involved but Googling reveals between 20 and 40 volts. This will need to be knocked back to 2 volts which is typical of line level. As a reality check, it seems that most sub manufacturers build this into their kit, hence allowing a high level input in addition to the line level input.
A forum friend has purchased for me a unit like this.
(https://i.ebayimg.com/images/g/gPoAAOSw~o5ahv5-/s-l500.jpg)
https://www.ebay.co.uk/itm/SPEAKER-TO-RCA-CONVERTER-HIGH-TO-LOW-LINE-LEVEL-ADJUSTABLE-ADAPTER-2-CHANNEL/361987845604?hash=item5448282de4:g:gPoAAOSw~o5ahv5-:rk:5:pf:1&frcectupt=true (https://www.ebay.co.uk/itm/SPEAKER-TO-RCA-CONVERTER-HIGH-TO-LOW-LINE-LEVEL-ADJUSTABLE-ADAPTER-2-CHANNEL/361987845604?hash=item5448282de4:g:gPoAAOSw~o5ahv5-:rk:5:pf:1&frcectupt=true)
It looks to be suitable but with a 40 to 1 reduction he has modified that to just 20 to 1 with a change of resistors. I should get it in the post next week hopefully with a diagram of whats inside :)
If this works OK by feeding the resultant signal to a Rotel integrated amp then I am good to go on ordering the MiniDSP to set up a low pass filter.
Long term there may be higher quality speaker to line level converters that I can get, but for now its a step forwards.
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My matching super tweeters are now in place. The mounting is intended to get the voice coils of all drivers close and in the same vocal plane.
Initially they are upward firing and a variety of caps are available to set the high pass frequency. Let the experiments begin. :)
(https://www.audiocircle.com/image.php?id=190783)
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Result.
With a 0.47uF capacitor they have slipped into the OBs perfectly. Their presence can’t be detected, but there is an additional ‘air’ to the presentation which I like a lot. I suspect as they run in, there may be further gains.
Happy boy. Thanks Matevana for the recommendation
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I am now looking to improve the 4" high frequency drivers.
I have available vintage Alnico drivers including Saba, 'small' magnet Grundigs, larger magnet Grundigs and my latest purchase is a pair of Klangfilm drivers. These have BIG horse shoe magnets (see picture)
If the weight of drivers correlates to the weigh of the Alnico magnets there is an interesting comparison.
Sabas 105gm
'Small' magnet Grundigs 236gm
Larger magnet Grundigs 330gm
Klangfilm 555gm
(https://www.audiocircle.com/image.php?id=193276)
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(https://www.audiocircle.com/image.php?id=193276)
Wow, looks a great driver large magnet, how is the sound from this driver?
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Just got them and at present I have only checked that they are working OK. Certainly sound more alive than the Grundigs they will replace.
They don’t have screw holes, so I need to find a way to mount them. :)
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The pressure ring dont came with the driver?
The magnet cover cant be put near metal.
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The pressure ring dont came with the driver?
The magnet cover cant be put near metal.
No there isn’t a pressure ring, but the drivers are probably 65 years old so they went missing along the way.
My drivers are recessed into the baffle from the rear so may hold them in place with a rubber strap stretched across the magnet and fixed into the rear of the baffle either side of the driver.
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Wood or alu rings are the material less prone to disturb the magnet.
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Good suggestion. I am currently thinking something like this. https://allensportsusa.com/products/4-rubber-straps.
This will also add some damping.
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How these belts could be implemented?
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How these belts could be implemented?
I will post a picture when I experiment later.
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Here's a picture of a cobbled together prototype.
(https://www.audiocircle.com/image.php?id=193511)
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Hm, there is any photo from the face cone side?
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Hm, there is any photo from the face cone side?
There will be one along later :)
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There is any space for metal clamps?
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There is any space for metal clamps?
No room for metal clamps in my baffle, but this system will work out ideal. From the front one would never know.
(https://www.audiocircle.com/image.php?id=193568)
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I have now found a very suitable amp for bass duties. With DSP there are additional demands on the amp to provide power at specific frequencies. This places big demands on getting it right.
This amp delivers 1000W of quality sound per channel into 4 ohms. That should suffice.
(https://www.audiocircle.com/image.php?id=193937)
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I am so pleased with the way my system is developing. The ICE power works perfectly. It is capable of delivering 2x1000W into 4ohms and drives the 15" Altec 416 8A beautifully. My low pass filter is set at 80Hz at present with 24bd slope.
To remind you, the midrange SEAS Exotic W8 runs full range without any cross overs and the high frequency Klangfilm 4" has just a single capacitor for high pass.
My next task is to upgrade the signal path to the ICE Power. This will involve a custom built voltage divider to replace the £6 device from E Bay, a linear power supply for the miniDSP to replace the existing switching power supply, and installation of a MUCH better volume control than the relatively OK pot installed at present.
It seems a lot of trouble to go to for frequencies below 80Hz, but I am discovering more and more that its these low frequencies that underpin and carry along any tune.
Pictures to follow.
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There is one other thing I need to try.
Now my 211 triode amp is removed of the need to drive the 15inch bass, the triode amp has a much easier life. My intention is to substitute the 20 watt 211 amp with 1.8 watts of DRD 45 triode amps. The sweetness of the 45 triodes needs to be investigated.
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Hi, Interesting development. Regarding the temporary experimental baffles forming U frame, if they splay outwards 1" for every 6" of depth you will not have problems with standing waves. When I experiment I take mods to the extreme so there is no mistaking the effect the new tweak is having and then tune from there. Perhaps revisit the U-frame with side panels about 15'' deep and lined with some carpet or underlay or similar. I suggest not making them too tall so as to not interfere with the upper range and consequently the imaging.
I use Omnimic from Parts Express to measure, great value, simple and has a forum for questions and guidance. Think I paid about $350 Have to say this: a mediocre mid and tweet properly configured will sound better than using the world's best and most expensive mid range poorly integrated.
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Thanks Sailor, for a long time I have been convinced I am talking to myself on here :)
I have noted your comments on a mild flair for the U frame, it makes good sense, and I'm sure I will revisit it. I have already discovered the need to limit the height so as not to affect the mid/high frequencies.
I agree on the need for proper integration and is one of the arguments for finding, say a mid driver, that can be run over its full range without the need for crossovers to remove distortions at the frequency extremes. Unfortunately this type of driver does not come cheap.
My philosophy, that relies on good listening, is to find a mid driver that can play to its full range and then bring in the tweeter and bass outputs to 'kiss' it. It’s pretty easy to tell when you have gone too far as the mid range magic is sat on.
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I way back had a Fostex 103 running full range in a Zigmahornet making surprisingly good sound but a 4" driver will obviously be bass challenged so I inserted a notch filter consisting of a cap, resistor and inductor all wired in parallel and this combo in series with one speaker connection to driver. This is not a crossover as such but was used to tame an annoying rising response in the upper mids. By attenuating a narrow band of higher frequencies there was a fuller sound by creating an apparent increase in bass and for background music was OK but it totally killed the little speakers sparkle and fun and was soon removed.
This is a long winded way of saying that everything matters and if you can use your mids full range do so but its seldom possible. I have found just using resistors to attenuate colour the sound with the ubiquitous sand-cast ones being the worst offenders. Measurement will reveal the effect of tweeter overlap on the mids.
I have not played with my kit for some while, busy trying to sort out a leaky house. When I get started again I have a pair of Tannoy MG15's to try out OB and to install some room treatment, speaking of which, do not underestimate the dramatic effect correct acoustical treatment will have. This is something overlooked by most!
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I am currently pretty happy with how my OBs are sounding. Recording made on iPhone.
https://youtu.be/RmQFTLxx3d8]https://youtu.be/RmQFTLxx3d8]https://youtu.be/RmQFTLxx3d8 (https://youtu.be/RmQFTLxx3d8)