The BlindStone OB

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Rudolf

Re: The BlindStone OB
« Reply #20 on: 8 Dec 2010, 09:11 pm »
Moving from placing the Neo on the back of the baffle to the front does not change the forward alignment very much, shouldn't we see more difference ? There was no optimization with regard to the forward response in this case, everything remained the same as it was when the Neo3 was placed at the back of the baffle.

Erling,
moving my tweeters did not change my forward response much either. From a planar tweeter I would expect even less change. Logically we both had already optimized the response for the front area. When I inverted my tweeters out of curiousity, the 2 kHz dip immediately jumped from the back to the front, and the radiation to the back became desensitized to change.

I believe it is the lack of symmetry in the cone driver which does not allow a perfect alignment. We would need different low-pass types or even different filter orders for front and back to get it right - something that yet has to be invented. :)

Rudolf

Bonzite51

Re: The BlindStone OB
« Reply #21 on: 9 Dec 2010, 12:39 pm »
Thanks,

I will go a little bit further in explanation. Evidently the 6ND430 is a good speaker. At least the best dynamic midrange I have played with so far. I am a bit jealous about the Neo10s which couldn't be delivered to me by 'black import' at Easter time this year. I have had a long going mail discussions with Sales Managers at B&G Radia about this unit going back to the time ProRaum in Germany put out a design with them. Meniscus was telling they would sell them eventually but couldn't meet my time window this time. May be later. I have no doubt they are great. 6ND430 is a very good alternative though.

The most real improvement in this design is the division of Bass- and Mid- Tweeterpanels. Definition is absolutly improved by avoiding bass influences to spread via the baffle to the other units and may be also overall clarity. It is easily heard and does imply restrains for building with all units on the same baffle.

Regarding the No Baffle experiments I was surprised by the great variation in response that I found. I have no good explanation to the thruth that I got very much more consistent and likeable ('realistic') results just from putting a small baffle like my 20 cm (8"). Without baffle I had a massive EQ with 15 dB shelving going to put out level sound with 300 Hz as crossover frequency. With the narrow baffle I can go down to 250 Hz without EQ, why ? To me the Constant Directivity argument is valid. We probably play in more symmetrical environment most of the time to make the intuitive strenght of the argument valid. Also some toe in of the speakers seem to improve the stereo sweetspot.

Regading Rudolf's question about angeling the bass panels I have no answer yet. Too little time to try. But I don't suspect any radical improvments in my room. Bassresponse doesn't seem that sensible. The room is fairly lively I think but seems to do OB sound justice.

P.S. I had favorable comments about the Neo3 performance in Uppsala.

/Erling

Hello Erling

Congratulations regarding this new project!

I am interested to even less - for example did You tried without this midrange 6ND430, just Alphas with Neo?
Sorry, for this question if this is already discussed here.

Janis

scorpion

Re: The BlindStone OB
« Reply #22 on: 9 Dec 2010, 04:15 pm »
Hi Janis,

Thanks. I don't think it will be possible to mix Alpha15 and Neo3 only with any good result. Also as witnessed by for instance the development of Emerald Physic's CS speakers a good midrange speaker will produce better sound and have better overall characteristics performencewise than the big 15" bass unit in this chritical frequency band.

So, no I didn't try.

/Erling

scorpion

Re: The BlindStone OB
« Reply #23 on: 13 Jan 2011, 03:27 pm »
I have further reduced wood consumption for the Blindstone.

Eminenca Alpha15s are replaced by AE IB15, just a pair of them. I put them up because of a thread in our Swedish HiFi Forum regarding IB15 and Dipole15 in OB.
I thought I could say something about the IB15 potential there so a quick fix.



Well the IB15 will stay. I have previously aired that I thought the Alphas the weakest link in The Blindstone. So it was.

In fact the whole speaker reached a new level in definition and clarity. Drumtransients are a pure fun as is also the rest of the music.  :D

Today, saturday, I have supplied CD after CD for playup. I am still amazed. It is quite in the league among anything I ever heard from dynamic speakers, except some electrostatic designs like Quad or ML.
In fact the IB15s were waiting for some electrostatic panels to arrive, but when that will happen is written in the stars.

/Erling
« Last Edit: 14 Jan 2011, 10:37 pm by scorpion »

ific

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Re: The BlindStone OB
« Reply #24 on: 16 Jan 2011, 11:32 pm »
I have further reduced wood consumption for the Blindstone.

Eminenca Alpha15s are replaced by AE IB15, just a pair of them. I put them up because of a thread in our Swedish HiFi Forum regarding IB15 and Dipole15 in OB.
I thought I could say something about the IB15 potential there so a quick fix.



Well the IB15 will stay. I have previously aired that I thought the Alphas the weakest link in The Blindstone. So it was.

In fact the whole speaker reached a new level in definition and clarity. Drumtransients are a pure fun as is also the rest of the music.  :D

Today, saturday, I have supplied CD after CD for playup. I am still amazed. It is quite in the league among anything I ever heard from dynamic speakers, except some electrostatic designs like Quad or ML.
In fact the IB15s were waiting for some electrostatic panels to arrive, but when that will happen is written in the stars.

/Erling


Hi Scorpion,

I really like your design.

What F3 are you getting with the IB15?

Thanks.

Ific.

scorpion

Re: The BlindStone OB
« Reply #25 on: 17 Jan 2011, 07:12 pm »
Really, if I believe my measurements F3 is more close to 20 Hz than 30.
And I think is is correct. Room is about 7 x 5 x 2.3 m.  Remember EQ. :)

I see now I never commented EQ here, it's a shelving  LP filter 12 db/oct at 40 Hz + 7.4 dB which following the DCX display is closely approaching an MJK model simulation for the IB15 and baffle.

/Erling

scorpion

Re: The BlindStone OB
« Reply #26 on: 18 Jan 2011, 05:37 pm »
Because of another IB15/Dipole15 question I tested some different LP crossover frequencies with the IB15. Test were made with Human Voice Speech from Radiobroadcasts. This was the result:

300 Hz: Probably worse than the chosen 250 Hz, prolonged listening I think would have been in favour of 250 Hz.
400 Hz: No question much worse than than 250 Hz.

So, like AE have stated 250 Hz seems a good max LP crossover frequency for IB15.

/Erling

Mr Ed

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Re: The BlindStone OB
« Reply #27 on: 21 Jan 2011, 02:48 am »
Very intersting Erling :)
I have a pair of Alpha 15 still new in their box. I may not even open them, instead I might try the AE dipole15. I have always been wondering about clearity with the Alpha.

Ed

ttan98

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Re: The BlindStone OB
« Reply #28 on: 21 Jan 2011, 04:05 am »
Very intersting Erling :)
I have a pair of Alpha 15 still new in their box. I may not even open them, instead I might try the AE dipole15. I have always been wondering about clearity with the Alpha.

Ed

If you compare the price difference between AE15 and Alpha 15, I am sure you will find the some if not large differences in their sound reproduction. In favour of  AE15 of course.

Enjoy your AE15. I wish I have a pair, by the time they arrive in Australia, the actual price will multiple by at least 1.2-1.5 times.

Ric Schultz

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Re: The BlindStone OB
« Reply #29 on: 27 Apr 2011, 07:20 pm »
OK, I am going to push you guys.  I want you to have the best sound possible.  You really must damp everything, time align all drivers, get rid of unnecessary connections, use good parts and get your cables off the floor:

Damping:

If you do not have constrained layer damping material (best is EAR SD40AL) on every inch of the back of the baskets on your Alpha woofers you will never know how tight and clean they are.  NOW HEAR THIS!: a friend who has 2 damped Alphas on a constrained layer baffle has just epoxied a piece of plywood between the two woofer magnets and this piece of plywood also extends all the way to the floor and is mounted to the bass of the speaker.  Between the two drivers another piece of wood is mounted between this brace and the front panel.  He will be listening to the results of this tweak in the next couple of days and I will update this post and have pictures.  Have you seen that Linkwitz has his cast frame midrange driver on his open baffle speaker mounted by its magnet?  If it makes a midrange better, imagine what it would do for woofers with resonating stamped frames?

By the way, every driver will sound better with its basket damped (cast or stamped).  Also every driver that I have tried sounds better with Deflex Magnepads mounted on the back of the magnet (no way can be as good as hard mounting the magnets, however).

Your drivers (mids and highs too) must be mounted on a seriously rigid and stable baffle.  You really should use multiple layers and use damping glue in between the layers.  Also, you HAVE to brace the speaker baffle.  It cannot be floating free in the air.....I don't care how massive it is....it still benefits from a brace.  Check out the $120,000 Granada speaker on the Lotus Group site.  His 3 inch thick birch plywood panel still has a brace on one side (three inches thick and still needs a brace.....get it?!?).

I am not going to tell you that damped and magnet held Alphas mounted on a super rigid baffle are going to sound as good as non tweaked IB15s....I have no idea.  But two undamped? Alphas on two thin resonating pieces of plywood hooked together with a vibration prone hinge and angled so their phase is screwed up?  Yikes!!!, that is going to sound horrible!!!!


Time Alignment: 

If you are using a digital xover system then you usually have an electrical way of delaying the higher frequency drivers......IF you are using analog xovers you must time align the drivers.  If you mount say two Alphas and some other full range driver on the same baffle the sound from the full range driver will hit your ears first....not good.  You can temporarily mount the higher frequency driver on a separate baffle and move it back relative to the woofers till it sounds correct.  Obviously, having a separate baffle for the mids/highs can be beneficial as the bass is not coloring (moving) the midranges.  But if you going to use only one baffle then you can mount the midrange/tweeters by the rear of the baffle for offset or if the baffle is thick enough you can route it down enough and mount it from the front.  Tweeters (as shown) can be mounted directly over the midrange baffle on their own damped baffle and set back for time alignment.  Whatever you do, you still need all drivers mounted on a super rigid baffle.  Please use felt around the front of the mids and high freq drivers as this will kill defraction.

Get rid of unnecessary connection:

What are binding posts, spades and bananas good for.  NOTHING!  Absolutely nada.  If you must have a connection that you can disconnect quickly from then use binding posts as a wire to wire clamp.  All binding posts and speaker connections mess with the sound.....Have not used them in 25 years.  Every person who has hardwired or hardclamped has to scrape their jaw off the floor after removing all this JUNK!  Do not use push on connectors to mount the speaker wires to the driver.  And solder your speaker wires directly to the eyelet that the wire from the voicecoil is mounted to.  Do not solder to the other side of that tab.  It sounds better, especially on a midrange/tweeter.  If you are worried about overheating the voice coil when soldering to this point then just heat sink the voice coil wire while soldering.  IF you hit it hard and fast with a serious hot and large iron then there will never be a problem (have done this for years).  Please don't get me started on alligator clip leads....oh my GOD!  Steel Alligator clips!  You have to be out of your mind!

Use good parts: 

Don't use the cheapest coils for the woofers.....get the big guns.  Those 14 guage ERSE iron cores cost nothing.  Use brass screws to mount the drivers.....sounds better.  Use high density plywood or use highly refined MDF like Rangerboard, Medite or Plum Creek.  This highly refined stuff is more dense and sounds better.  Use two or more layers with Green Glue in between.  If you brace, then use a brace that is dead.  If it is steel, it will probably vibrate so it needs to be damped with SD40AL.  Above all else.....think!  Use your brain.  Think and live low distortion.  Get rid of all unnecessary parts, and tweak like crazy what is remaining.

Get the stuff off the floor!:

No cables (AC, speaker or interconnect) should be anywhere near the floor..........this goes for xover parts too.  No coils sitting on the floor.  You can even use cardboard to raise the cables off the floor.  Way more pure and spacial sound.  If one of my cables touches the floor for one inch, it is noticeable on my system.  The more you tweak the more each tweak makes a difference.  If you have 100 veils and you remove one then there is hardly any difference, but once your system is tweak....then each tweak makes a serious difference.

I am going to be putting a speaker building DIY site off my website that will have pics and links to all of the above and way, way more. 

The difference between doing something good and GREAT is really not that much.  A few more hours, a few more dollars and now the speaker sounds like a $20,000 speaker instead of a $5,000 one.  If you do not really care about great sound then throwing things together can be fun.  What I want is musicians in the room.  Not a bunch of resonances and messy sound.

So, am I pushy enough?  He he.

« Last Edit: 27 Apr 2011, 08:22 pm by Ric Schultz »

scorpion

Re: The BlindStone OB
« Reply #30 on: 6 May 2011, 05:00 pm »
Hi Ric,

Thanks for the comments. Sorry I missed them some time. A bit off the Blindstone design I am afraid.

Although I agree with most of your statements. Not many apply to my Alpha treatment.

Alphas are heavily damped by 4 mm bitumen on every leg and also felt inside legs. This was from my Emerald Physics clone experimnts. So I don't think chassies could have been better treated. I also think that magnet mount is good. I had very early experiment somewhat successfully with blindrope fastening to prevent resonance.

Now the AE IB15 is mounted on a 28 mm thick birchtree baffle, ok I think.
I am of no concern about the mid- and tweeter units although on 18 mm spruce baffles there is no trace of resonance and if there should be I think spruce is adding and not subtracting to sound experience.

No, I am afraid the IB15 is addning much less colouration to the sound then the Alphas. Listening too long to your speaker without any reference can mislead yourself. Now I am not saying the Alphas are bad, just that the IB15s are a class better.  :)

The setup is actively driven.

/Erling

Ric Schultz

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Re: The BlindStone OB
« Reply #31 on: 8 May 2011, 06:23 pm »
I have no idea what Bitumenous felt does to damp a woofer frame but I bet it is less good than the EAR SD40AL damping material.

But mounting the Alpha woofs on thin wood connected with a hinge and no bracing on the magnets....this is not going to sound good.  If you are going to use two Alphas and you want it to sound the best it can then you want at least a 2.25 inch constrained layer baffle that is also braced and you want to hardmount the woofer magnets to the stand.  And of course, you would want them on the same baffle and not pointed in different directions.  You would be blown away how much better this sounds.  Would it sound as good as an IB15 mounted the same way......probably not.  Would it sound as good if not better than your current IB15 setup......I bet it would.  Now if you did the same mounting to the IB15 then you are through the roof.  As long as you are listening to your current reference mountings then you can mislead yourself.....he he.....

You had stated that your current speaker sounded as good as any cone driver speaker you had heard but maybe not as good as the best electrostat.  I content that if you mounted your IB15 REALLY seriously and mounted your midrange and tweeter REALLY seriously you would think you transcended the best panel speaker you have ever heard.  You are not listening to the drivers the way you have them mounted.  You are listening to vibrating panels and a vibrating tweeter....no doubt.  One inch thick or less undamped and unbraced panels is not serious.  Make all you panels like Studiotech, brace them and magnet mount all the cone drivers......this will blow your mind!!!!!!!!!!!!!!!!!!!!!!!!!!!

I will have a post with pictures in a day or so that shows a highly modified Emerald Physics speaker with both Alphas magnet mounted.  I will have the comments from the person who did it.  Please read.  This will be very informative.

Yes, it is Sunday and I am preaching!  Can we get an "AMEN"........Happy Mothers day!

scorpion

Re: The BlindStone OB
« Reply #32 on: 8 May 2011, 08:58 pm »
May be you don't have this kind of asphaltrubber sheets over there, it is not any kind of felt.
You usually by it in car accessories shops, they use it to prevent panelresonances of any kind.
It is quite hevy and in test proven as good as any special resonancedamping material.

Of course, Ric, I will not prevent you from building as good an Eminence Alpha 15 speaker as possible.

Myself I will stay with the IB15.  :green:

/Erling

mcgsxr

Re: The BlindStone OB
« Reply #33 on: 8 May 2011, 11:43 pm »
I believe the north american equivalent to what Scorpion is referring to is similar to Brown Bread, or Dynamat Extreme.

I won't comment on it vs what Rick is discussing, as I have not used both materials.

I will say that I agree with Rick in this sense - if you mount a woofer or subwoofer to an OB, and don't brace it well, you will hear the panel a lot - I am living it!

doug s.

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Re: The BlindStone OB
« Reply #34 on: 9 May 2011, 09:10 am »
May be you don't have this kind of asphaltrubber sheets over there, it is not any kind of felt.
You usually by it in car accessories shops, they use it to prevent panelresonances of any kind.
It is quite hevy and in test proven as good as any special resonancedamping material.

Of course, Ric, I will not prevent you from building as good an Eminence Alpha 15 speaker as possible.

Myself I will stay with the IB15.  :green:

/Erling
erling, ric is not saying don't use the ib15 - he is saying if you brace it much better, you will get much improved results.   :wink:

doug s.

JohnR

Re: The BlindStone OB
« Reply #35 on: 9 May 2011, 09:34 am »
Well... it does seem to be a characteristic of the OB circle that everybody wants to second-guess everybody else's project. Frankly, worrying about what material the screws holding your driver are made of more than the quality of the driver itself seems a little... well, "out there." I have no doubt at all that the baffle density/damping/mounting have an effect... but OTOH I see it as a "known" factor - something that can be improved or optimized later, after all the measurable issues are taken care of.

doug s.

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Re: The BlindStone OB
« Reply #36 on: 9 May 2011, 10:29 am »
i agree - worrying about what type of screws are being used might be a bit obsessive.   :lol:  on the other hand, the point i think ric is really trying to make is that going from 0.75" to 2.25" thick baffle is a game changer, at least equal to upgrading the driver itself.

doug s.

JohnR

Re: The BlindStone OB
« Reply #37 on: 9 May 2011, 10:39 am »
28mm is not exactly equal to 0.75"...

Regardless, I'd have to say I'm pretty dubious about the relative merits of baffle thickness and damping versus a higher quality motor and cone. You can't remove distortion once it's introduced. I'd be very interested to find measurements that demonstrate the (audible) effect of various baffle thickness/damping strategies. Not to say that measurements are everything but I'm learning that it is at least helpful to get those right first.

doug s.

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Re: The BlindStone OB
« Reply #38 on: 9 May 2011, 10:58 am »
28mm is not exactly equal to 0.75"...

Regardless, I'd have to say I'm pretty dubious about the relative merits of baffle thickness and damping versus a higher quality motor and cone. You can't remove distortion once it's introduced. I'd be very interested to find measurements that demonstrate the (audible) effect of various baffle thickness/damping strategies. Not to say that measurements are everything but I'm learning that it is at least helpful to get those right first.
sorry john, you are correct - 1.1" is certainly better than 0.75", even if a bit less than half of what's recommended by ric.  my sloppy reading; i only saw the 18mm dimen given for the mid-tweet baffle.

And i do not disagree that, all other things being equal, better driver is important.  i guess what is unclear, is how "unequal" do things have to be, before a lesser driver will outperform a better one!   :wink:

doug s.

JohnR

Re: The BlindStone OB
« Reply #39 on: 9 May 2011, 11:09 am »
Yes, exactly ;) It's a good question.