AudioCircle
Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: DeeAlfred on 7 Sep 2017, 05:14 pm
-
Hello guys!
I've been following the OB section of the forum now for a while and truly respect all your great work and information you share here!
Now it's time to build my own OB speaker.
I Build some boxed designs before but when I first heard OB I decided to build one!
I already decided to use the Eminence Alpha 15a (maybe upgrade to 2 per if needed) in an H-Frame design but as I'm looking for a full range driver now there are way to many options out there, from 3 to 8 inch. Maybe someone could help me there and has some suggestions.
The System is going to run full digital and active with a MiniDSP 2x4HD as crossover powered by a Cambridge azur 640a and a pro-amp for the Alphas.
My preference for listening are vocals and blues. Especially great saxophone recordings.
My listening could also get a little louder from time to time.
The room is about 30m2 if that matters.
The budget for now is about 200€ for the Fullrange.
Since I want to try different Fullrange drivers this is not gonna be the last one and I'd like to switch back and forth later do find what I like. Until I have more time for experimenting with the drives you may have some suggestions for the first one?
Thanks!
Chris
-
"The budget for now is about 200€ for the Fullrange." each ?
-
"The budget for now is about 200€ for the Fullrange." each ?
200€ total for both fullrange drivers
What will be the tonal difference between using an 8" or for example a 4" chassis?
Greetings
Chris
-
More importantly, how low will your FR driver run and sound good. If you brace the magnet on the alpha you can get great sound quality up to 350hz, so your FR will need to go down to 350hz, reducing the frequency range it will have to cover.
-
If you could stretch your budget just a little bit, consider the Fostex FX120 or the FE-108E Sigma full range drivers.
https://www.madisoundspeakerstore.com/approx-5-fullrange/fostex-fx120-5-full-range/ (https://www.madisoundspeakerstore.com/approx-5-fullrange/fostex-fx120-5-full-range/)
https://www.madisoundspeakerstore.com/approx-4-fullrange/fostex-fe108ez-4-full-range-sigma-series/ (https://www.madisoundspeakerstore.com/approx-4-fullrange/fostex-fe108ez-4-full-range-sigma-series/)
Implement an acoustic crossover (using passive or active electrical crossovers will work) at about 200 Hz on both the woofer and the full range driver. This will produce a relatively inexpensive OB speaker system that will perform well above its price point. Make sure you use a SS amp if you plan on using a passive crossover.
-
On Ferrite magnet my suggestion are the Visaton B200,
already know as good sound in OB.
-
the b200 will drill the head :)
and you will need 4 alpha
-
How it is? do you could explain?
Its due 96dB sensitivity?
-
I am really enjoying my Jordan Eikona 2 full range drivers. I have played with a few other small full rangers, but keep coming back to the Jordans.
-
I agree, Jordans are also good OB drivers. Unfortunately I have not heard a pair of the new Eikona drivers. I would like to but don't think it will fit in with what I am working on at the moment. Maybe someday in the future.
-
I agree, Jordans are also good OB drivers. Unfortunately I have not heard a pair of the new Eikona drivers. I would like to but don't think it will fit in with what I am working on at the moment. Maybe someday in the future.
Martin,
If you are ever in the South Florida area, let me know. I would be glad to demo them in my OB setup. The Eikonas have a similar personality to the JX92s, but are a little more dynamic with a clearer top end (i own both). The new ScanSpeak motor is also a big improvement over the first generation; they are able to play louder with less distortion. I actually have mine running full range with no highpass. At my listening levels, the intermodulation distortion isn't bad at all.
-
FF85wk, Alpair 7.3/6.2/5.2 will all work. The A7.3 in particular is outstanding.
dave
-
If you are ever in the South Florida area, let me know. I would be glad to demo them in my OB setup. The Eikonas have a similar personality to the JX92s, but are a little more dynamic with a clearer top end (i own both). The new ScanSpeak motor is also a big improvement over the first generation; they are able to play louder with less distortion. I actually have mine running full range with no highpass. At my listening levels, the intermodulation distortion isn't bad at all.
Shoveled snow in 0 deg F this morning, not including the wind chill. It was 1 deg F this evening when we went out to dinner, so by tomorrow I am expecting even colder below zero temperatures.
Just got back from a few days visiting my older daughter where it was a balmy 25 deg to 35 deg F.
What the hell am I doing, Southern Florida sounds awful good right about now. Thanks for the invite, one day I will come to my senses and visit Florida and take you up on your offer to hear the new Eikona speakers. Unfortunately, it is back to work on Tuesday and for the rest of the week in this frigid start to January in Upstate NY. The only upside in my life right now is that my son lives and works in the snow belt out by Buffalo, it is all relative so his life sucks more than mine.
-
Don’t want to hijack this thread but I too need to make a decision on a mid-driver for my OB “science” project (will be pairing with a single Faital 15PR400). Efficiency is high on the requirement list since I’ll be (eventually) driving the mid’s bi-amped with a 300B kit.
Initially had my eye on the Fostex FE206En for price and efficiency ($118ea 96db). But, the Tang Band W8-1808 caught my eye after researching the Pure Audio designs and reading reviews.
Now my question – has anyone compared the Jordan Eikona 2’s to the TB 1808’s? They both seem to be about the same price range, though the TB being more efficient.
Thanks… and a Happy New Year to all… and Stay Warm!
Dave
-
I bought my Eikonas from a gentleman who owned two pairs from a group buy. He kept one for himself and sold the other. He also owned a pair of 1808’s. He liked them both for different reasons and commented on them being polar opposites.
I suspect the Jordans are more refined (polite) and smooth. The TANG bands with their much larger radiating surface may be a bit more dynamic but I suspect can sound shouty depending on the recording.
-
I agree, Jordans are also good OB drivers. Unfortunately I have not heard a pair of the new Eikona drivers. I would like to but don't think it will fit in with what I am working on at the moment. Maybe someday in the future.
Martin,
With apologies to DeeAlfred, are you willing to describe what you are working on currently?
Thanks,
-
With apologies to DeeAlfred, are you willing to describe what you are working on currently?
I am updating all of my horn math and MathCad worksheets extending them beyond what is usually seen in the popular horn simulation programs. I have an outline of a new set of presentations that I am populating. This is a long term effort, I am already one year in and not even close to being done.
-
Paper cones have a organic sound that is more enjoyable than alu and mainly plastics.
-
i didn't think of getting any response anymore. Cheers to all!
It's time for a little update:
I've ordered a pair Beta15A cause the Alphas were sold out everywhere close (I'm from Austria), to experiment with since i thought the bass driver is the weakest point in my current system, didn't like it (Gradient AXP12, vented). So i put the Betas into the H-Frame design from MJK (thanks for all the inspiration and things I've learned from you at this point!) with a bigger crosssectional Area of 46x46cm and the suggested depth for XO at 200Hz.
At the moment these are crossed to a GAM100 AMT sandwiched between 2 Gradient AXP06 via a miniDSP 2x4HD. XO is a LR12db at 150Hz to make it perfectly flat up to 250Hz. Got pretty hard EQ on the low end of up to 13db at 25Hz. This gets me a flat response at 1m down to 22Hz.
The bass now sounds amazing to everything else i heared before! Some Friend who came over couldn't believe it first hahaha they've never heard real bass before.
For the future I'm planning on implementing a second Beta15A each side to take minimize the stress on the woofer. I'm watching a lot of movies with this system as well and it happend before that the woofer hit Xmax before at some really low Frequencies. to solve it for now i highpassed the sub at 22Hz at the moment.
For music one woofer would be more than enough since you're not playing as low frequencies i guess.
Still an OB FR driver has to be implemented which will come next..
If you could stretch your budget just a little bit, consider the Fostex FX120 or the FE-108E Sigma full range drivers.
https://www.madisoundspeakerstore.com/approx-5-fullrange/fostex-fx120-5-full-range/ (https://www.madisoundspeakerstore.com/approx-5-fullrange/fostex-fx120-5-full-range/)
https://www.madisoundspeakerstore.com/approx-4-fullrange/fostex-fe108ez-4-full-range-sigma-series/ (https://www.madisoundspeakerstore.com/approx-4-fullrange/fostex-fe108ez-4-full-range-sigma-series/)
Implement an acoustic crossover (using passive or active electrical crossovers will work) at about 200 Hz on both the woofer and the full range driver. This will produce a relatively inexpensive OB speaker system that will perform well above its price point. Make sure you use a SS amp if you plan on using a passive crossover.
Thanks for your suggestions MJK! I've already read about you liking the 108EZ sigma. If the 4 inch driver goes down to 200Hz anything bigger would be not worth it? And it may have disadvantages at the HF?
I'm just considering a bigger driver due to the fact I'm listening loud from time to time. If i calculated right the FE108 will have a max of 99dB which should be plenty. Does it still sound as light and good at it's maximum power ratings? Budged wise I'm able to spend a little more now.
Would you suggest the SS amp for the FR driver or the LF? I'm currently using a pro amp with 2x400W for the Betas. I got a 4xEL34 14Watt tube amp i build as my diploma thesis as well. What about using the tube for the FR? Or will my current Cambridge 640A do the better job?
I'm willing to update you with some pictures of the current configuration if u're interested :)
-
the b200 will drill the head :)
and you will need 4 alpha
What do you mean by drilling my head? haha since I'm XO active the sensitivity wouldn't be a problem.
FF85wk, Alpair 7.3/6.2/5.2 will all work. The A7.3 in particular is outstanding.
dave
Thanks for the suggestion, didn't know them. I'm looking forward to experiment with more drivers in the future and they are definitely on my list. I like them design wise as well!
At the moment I'm not decided on which driver to start with. i guess just getting one insted of thinking and waiting will be the better option to get the project going. :)
Paper cones have a organic sound that is more enjoyable than alu and mainly plastics.
I read a lot about that. looking forward to try it myself in the future!
Cheers!
-
I have an open baffle system I built. It has been shelved for some time because I need to figure out how I'm going to deal with baffle step correction.
It consists of a 15" woofer on a 48" x 18" flat baffle. The woofer is no longer made, but it was inexpensive with high Qts and high efficiency and I love it.
For the mid/high frequencies I can alternate between two drivers. I have drilled holes for both of them, but run only one at a time.
One is the Visaton B200.
The other a 3" Tang Band w3-871, no longer available.
I am using a JVC surround sound receiver to provide a cross-over to the woofer.
Without baffle step correction, the system sounds best crossed at the highest frequency allowed by the receiver 200Hz.
The woofer sounds excellent at this cross-over point, but it sounds even better crossed at 150Hz and better yet crossed at 120Hz.
The Visaton B200 has some great midrange magic. However, without baffle step correction and its naturally rising response the top end is a little hard to take.
I suspect it can be tamed with the right network, but how that would effect the midrange magic I do not know. The top end other than being bright though is not too bad.
The Tang Band w3-871 clearly has more accurate high frequencies than the Visaton B200. As a whole I find the w3-871 more enjoyable than the B200.
Both drivers really need some baffle step correction to get flat to 200Hz. Still the w3-871 seems flatter than the B200 across the listening band without any correction.
The setup with w3-871 almost works, and the system plays as loud as a care to listen, although it is not concert level loud by any means.
I suspect with a corrective filter though that I might run out of volume head room. The bottom end of the w3-871 sounds great, but doesn't quite have the magic of the B200 in the lower mids.
Maybe someday I will run this setup as 3-way baffle step corrected.
I will also mention that I have experimented with wings and that creates resonances I don't like and it effects dipole dispersion.
I really think a flat baffle is the way to go. It is also easier to move around.
I am really curious about the Tang Band 5" w5-2143. I have never heard it.
The frequency response graph looks too good to be true.
The on-axis response graph is better than the 4" and 6".
I'm thinking that if I wanted to make a 2-way work this might fit the bill.
-
Without baffle step correction, the system sounds best crossed at the highest frequency allowed by the receiver 200Hz.
The woofer sounds excellent at this cross-over point, but it sounds even better crossed at 150Hz and better yet crossed at 120Hz.
The Visaton B200 has some great midrange magic. However, without baffle step correction and its naturally rising response the top end is a little hard to take.
Avoid active correction on the B200 use only 5 or 10mm felt over the baffle, active correction will blur the image and cut the sweet B200 harmonics.
-
It has been shelved for some time because I need to figure out how I'm going to deal with baffle step correction.
There is no baffle step phenomenon in an OB speaker, this only occurs in boxed speakers where the rear wave from the driver radiates into the enclosure. Baffle step typically occurs in a boxed speaker in the several hundred Hz frequency range where the sound transitions from omni directional to forward directional based on the front baffle dimension.
In an OB speaker sound is radiated forward and backward so no baffle step will occur, low frequency cancellation will occur based on baffle size and woofer fs and Qts but this is a different design issue. Whatever problems you are hearing in your OB speaker is not baffle step, probably crossover design or a mismatch in driver output level between the woofer and the other driver(s).
-
As you are running a flat baffle you have the ability to run the 15 incher up to 500 to 1,000 then crossover to the 3 inch TB. It's tough to design a OB without measuring but with an electronic 2-way crossover you would be able to tune your system more than what your surround receiver can do.
You can find some of the used Behringer, ART, or Dbx electronic x-os cheap or your could do the Rolls https://www.parts-express.com/rolls-sx21-tiny-two-way-crossover-w-level-controls--245-1182.
Then there's a mini dsp...
-
As you are running a flat baffle you have the ability to run the 15 incher up to 500 to 1,000 then crossover to the 3 inch TB.
MJK’s passive baffle article is the quintessential guide to using a 15” and a small FR in an open baffle. Well worth following even if you are going active. A 2nd order filter with offset turnovers to deal with baffle response. Few 15” will reach 1kHz, Martin XOs the 15 in the mid 200s and the small FR in the mid 400s IIRC. Martin used a Fostex FE103e but later user implemenrtaions (including ours) was that the less efficient FF85k 3” was a better fit.
http://www.quarter-wave.com/OBs/OB_Theory.html
dave
-
Thanks for the comments. I was really just trying to convey my impression of the B200 and w3-871.
I used the term "baffle step" perhaps too loosely. I do understand that it is the back-wave canceling out the front-wave that needs to be accounted for.
I do have some fears moving forward though.
The first concerns how accurate a model I can get with a tool like Basta.
The second concerns how accurately I can measure the response.
I purchased a calibrated microphone a few years ago. It has just sat in its box. I don't know if it requires re-calibration or if usage will cause some break-in and then then need re-calibration.
I naively assumed the microphone itself was somehow tuned. Instead I just have a sheet of paper with calibration numbers. I don't really know what to do with these numbers. I need some software that I can input them into and that will correct its display output accordingly.
I don't have a stock room full of inductors, capacitors, and resistors. I don't look forward to having to tweak a circuit by experimenting with such parts.
So I lean towards something like mini-dsp.
Having to buy mini-dsp to further what was intended to be an inexpensive experiment is not too appealing. If only I had money to burn.
I don't really have a great space for an 18" wide baffle.
If I ever get this right and want to live with it, I need a better looking baffle.
Unfortunately for me, I have heard the potential. I'm sure someday I will get this working.
-
The first concerns how accurate a model I can get with a tool like Basta.
Accurate enough to design an OB geometry and crossover that will work the first time, you will not need to have a whole box of parts to tweak the crossover after the fact. Assuming your drivers are good quality and well behaved, a simulation using measured T/S parameters (if possible measured impedance and SPL) in a program like BASTA should be sufficient to get you 95% of the way to your final system configuration. Building an OB speaker without some measurements and simulation is nothing more than guess work and wandering around in the dark as you try to optimize the results. Quickest way to an optimized result is to engineer the design using measurements and simulation.