Let's see your OB SW-12-16FR GR Research builds! (And plans for my own)

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Architect7

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Though I am an extremely happy owner of a Rythmik FV15HP in my home theater, I had no idea GR Research made an OB servo sub until today.  As you can imagine, I am absolutely enthralled with the idea of servo OB subs.  I am planning a new OB build and have everything but subs and processor/preamp.  It will be:

RAAL 140-15D dipole ribbons
Acoustic Elegance Dipole6 mids (x2 per side)
Hypex 6-channel custom built amp
2-3 SW-12-16FR per side
2x370 GR Research amps
Something like an RME Fireface 800 for preamp/DSP

My old OB setup used 6x AE OB15's, 3 per side with ~350watts each.  This setup was my first love for OB bass, absolutely intoxicating.  Now that I have heard the FV15HP, I want the best of both worlds; OB bass with servo accuracy.  In the meantime, please show me your OB GR Research sub builds so that I may be inspired (and a little jealous).  Thank you!

ebag4

You are in for a treat.  You may or may not be aware that Danny used these drivers (servo subs) in 3 designs (so far).  Initially it was the V1 which I built, then came the Super V, and his last design, the Serenity Acoustic Super 7.  Here is a link to my build thread if you are interested:
http://www.audiocircle.com/index.php?topic=79985.0

The servo subs are a fantastic foundation for OB speakers.

Best of luck with the build!
Ed

Architect7

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Thanks!  Yes I have been drooling over your build since coming across it yesterday, absolutely beautiful.  Is it necessary to invert the middle driver or can all 3 be facing the same direction if wired correctly?

Also, has anyone attempted a hybrid cardioid design by combining sealed and OB servo subs?  I've heard of this being done over on diyaudio with other designs but never with GR drivers.

ebag4

Thanks!  Yes I have been drooling over your build since coming across it yesterday, absolutely beautiful.  Is it necessary to invert the middle driver or can all 3 be facing the same direction if wired correctly?

Also, has anyone attempted a hybrid cardioid design by combining sealed and OB servo subs?  I've heard of this being done over on diyaudio with other designs but never with GR drivers.
I believe Danny had the drivers reversed simply to balance the forces and weight acting on the baffle.

 I have no relevant information on the cardoid design other than to say I have never wanted for anything in the bass department when playing the V1s.

 Best,
Ed

Tyson

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I'm still working on my next set of speakers, which were originally going to be a clone/homage to the Serenity Super 7's, with 2 SW-12-16FR's per side with the dedicated servo amps, 4 of the Neo10 drivers per side, and a Neo3 tweeter. 

BUT, I've recently changed my mind.  Cause, you know, bigger is better.  Right now I'm thinking 3 of the sub drivers per side, 8 of the Neo10's and switching the tweeter to the Heil AMT, all of it used Open Baffle.

AKLegal

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I'm still working on my next set of speakers, which were originally going to be a clone/homage to the Serenity Super 7's, with 2 SW-12-16FR's per side with the dedicated servo amps, 4 of the Neo10 drivers per side, and a Neo3 tweeter. 

BUT, I've recently changed my mind.  Cause, you know, bigger is better.  Right now I'm thinking 3 of the sub drivers per side, 8 of the Neo10's and switching the tweeter to the Heil AMT, all of it used Open Baffle.

Sounds like a great project.  Are you designing passive crossovers or will you go active?

Ric Schultz

Tyson,
You will have an even frequency response from the line source of Neo 10s both horizontally and vertically.  However, it won't match the vertical dispersion of a single AMT tweet.  This is why almost all line sources have a tweeter line as tall as the mids.  Don't ever recall anyone doing what you are suggesting except for VMPS.....which though very good.....were not state of the art.  I would go with 6 Neo 10s, 16 Neo 3s and the three 12s on a flat separate baffle next to the line source.  This way you can time align the woofers to the already time aligned mids and highs.  If you are using digital xovers you can time align with them but I personally would not go with an H-frame unless you are crossing at 100hz or less.  I don't want the lower midrange coming out of a square tube and especially with one driver facing forward and the other facing rear.  Because they are in reverse direction from each other the two woofers are not in the same plane with each other.  You want your male voices to start in two different places and coming out of a tube?  If you put the mids and highs on a super wide baffle (like the big Genesis speaker) then the line source of Neo 10s could get into the low 100s.  As long as you felted the entire baffle it would disappear sonically.....of course you could curve it back as well.

Hey, maybe you are going to use 8 of the Neo 10s in a square with the AMT in between?  That would be wild.

A line source of Neo 3s will lower the distortion and noise in its range so that it would mimic a sound of a lower mass single tweeter in detail but with much greater dynamics.  You could cross the line source of Neo 3s as low as 1.5K.  By doing so you get even more transparent lower highs.

I personally would like flat woofer panels with 6 Servo 8s per side.  This way it is even faster and you have about the same area of movement as 3 12s.  If you want a little more power in the teens then add a couple of boxed servo 12s.....that would do it.  I want the fastest bass possible.

When you have drivers this transparent then everything you do is critical.  There are no stock digital xovers that are really up to par.  You can do a simple 12 db per octave xover between the 10s and 3s using state of the art parts and you will get seriously good sound.  I am designing a line level two way xover (active/zero feedback fet buffers) that will be state of the art for such a purpose (now we are triamping, of course).
« Last Edit: 4 May 2014, 08:29 pm by Ric Schultz »

Architect7

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Tyson,
You will have an even frequency response from the line source of Neo 10s both horizontally and vertically.  However, it won't match the vertical dispersion of a single AMT tweet.  This is why almost all line sources have a tweeter line as tall as the mids.  Don't ever recall anyone doing what you are suggesting except for VMPS.....which though very good.....were not state of the art.  I would go with 6 Neo 10s, 16 Neo 3s and the three 12s on a flat separate baffle next to the line source.  This way you can time align the woofers to the already time aligned mids and highs.  If you are using digital xovers you can time align with them but I personally would not go with an H-frame unless you are crossing at 100hz or less.  I don't want the lower midrange coming out of a square tube and especially with one driver facing forward and the other facing rear.  Because they are in reverse direction from each other the two woofers are not in the same plane with each other.  You want your male voices to start in two different places and coming out of a tube?  If you put the mids and highs on a super wide baffle (like the big Genesis speaker) then the line source of Neo 10s could get into the low 100s.  As long as you felted the entire baffle it would disappear sonically.....of course you could curve it back as well.

Hey, maybe you are going to use 8 of the Neo 10s in a square with the AMT in between?  That would be wild.

A line source of Neo 3s will lower the distortion and noise in its range so that it would mimic a sound of a lower mass single tweeter in detail but with much greater dynamics.  You could cross the line source of Neo 3s as low as 1.5K.  By doing so you get even more transparent lower highs.

I personally would like flat woofer panels with 6 Servo 8s per side.  This way it is even faster and you have about the same area of movement as 3 12s.  If you want a little more power in the teens then add a couple of boxed servo 12s.....that would do it.  I want the fastest bass possible.

When you have drivers this transparent then everything you do is critical.  There are no stock digital xovers that are really up to par.  You can do a simple 12 db per octave xover between the 10s and 3s using state of the art parts and you will get seriously good sound.  I am designing a line level two way xover (active/zero feedback fet buffers) that will be state of the art for such a purpose (now we are triamping, of course).

Great post, very thought provoking for my own build, especially because I plan to run the GR subs up to 300hz.

Any plans to make a few of your xovers for resale?  :D I was going to do a highend Firewire proaudio interface to cover the xover/balanced line driver need that I have, any issues you see with that approach?

Tyson

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I was just going to copy the MTM design of the Super 7, which has the Neo10's oriented horizontally and stacked 2 above, and 2 below, the tweeter.  Except I was going to do 2 more above and below to give me a total of 4 panels above the tweeter and 4 panels below the tweeter.  I know these drivers are crazy transparent, but I wanted to stack as many as I could in order to get more surface area so that there is more slam in the lower mids and upper bass. 

I'm using a miniDSP for my current speakers, which are active.  I know it's limiting me to an extent.  I've been considering a DEQX to replace it.

jtwrace

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I've been considering a DEQX to replace it.
I'm pretty sure Danny doesn't like them either though. 

Tyson

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But I do.

jtwrace

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Tyson

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I was also thinking that with the Neo10's and the AMT, they have such strong overlap, that I could probably implement a 1st order crossover and not worry about out of band nasties or driver breakup. 

Actually, Rick's idea of a giant square of Neo10's around the AMT sounds pretty interesting.  2 Neo10's above, 2 below, 2 to the left and 2 to the right of the tweeter.  It would be a coaxial planar magnetic speaker.  Hmmmm....

Architect7

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I'm pretty sure Danny doesn't like them either though.

Any idea what he recommends?

jtwrace

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Any idea what he recommends?


No idea but I'd guess that he would still prefer a passive crossover being that he sells all the parts. 


Here was his thought on the DEQX though:

Both the 12's and 8's are capable of playing up to a 300Hz crossover point. Two things though. One, try to avoid the 300Hz to 500Hz range for a crossover point. That is the heart of the mid-range. Get down to 200Hz or less and you avoid a ton of problems. Secondly, I consider the DEQX it be at the top of the currently available digital crossovers, but still budget to mid-fi in performance compared to what I am used to. It is a fun toy that will get you good sound, but not into the upper levels of high end audio.

Ric Schultz

What is nice about the Neo 10 and 3 is that they do not need any equalization or compensation.  So simple 12 db per octave xovers will work silly good.  My active crossover will be fixed at 12 db per octave.  You would set the levels between the amps with a single shunt resistor (no pots).  The only things in series with the signal are two zero feedback fet buffers and a few state of the art caps and resistors to do the filtering.....incredibly simple and miles ahead of DEQX or such.  This active xover would be for the mids and highs.  The bass xover is done in the servo amps.  Just a cap in series with the mid amplifier (or on the output of the active xover) would limit the lows going into the midrange (if needed).  If you are not listening that loud then you can run the Neo 10s wide open (am doing this right now with a single Neo 10 on an open baffle.....however, not recommended for super loud listening....in fact it will sound better with the cap in series when playing very loud).

What is nice about the Minidsp and the better sounding (but still not seriously good sounding) DEQX is that they are so versatile...you can use any slope of xover, tons of eq, time align, etc.  If your speaker needs equalization and such then they are fine...but don't expect you will hear every tiny micro vibration and thrilling harmonic shadings coming through these things when they are loaded with opamps, normal resistors, caps, power supplies, ADCs, DACs, cabling, connectors, etc.  Even my modified Behringer (good enough for serious high end!) will not be as transparent as my simple active xover.  If you can just use the digital thang in the bass and use either simple passive or active on the mids and highs...you have something really seriously transparent.  Using eq on the bass will let you tune your speaker to the room.....mucho cleaner sound with eq below 2-300 hz.

TomS

I was also thinking that with the Neo10's and the AMT, they have such strong overlap, that I could probably implement a 1st order crossover and not worry about out of band nasties or driver breakup. 

Actually, Rick's idea of a giant square of Neo10's around the AMT sounds pretty interesting.  2 Neo10's above, 2 below, 2 to the left and 2 to the right of the tweeter.  It would be a coaxial planar magnetic speaker.  Hmmmm....
Have you seen the Hawthorne AMT/waveguide? Looks pretty nice, and open baffle ready  :thumb:

http://www.hawthorneaudio.us/forums/viewtopic.php?f=1&t=4934

Tyson

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Can you buy it as a separate part from them?

TomS

Can you buy it as a separate part from them?
The biggest one is only available on their "Reference" series finished speakers, but the smaller ones are intended for DIY. Both of them go fairly low compared to most AMT's.

Danny Richie

I personally would not go with an H-frame unless you are crossing at 100hz or less.  I don't want the lower midrange coming out of a square tube and especially with one driver facing forward and the other facing rear.  Because they are in reverse direction from each other the two woofers are not in the same plane with each other.  You want your male voices to start in two different places and coming out of a tube?

It doesn't really work that way. Mid-range is really 300Hz to 500Hz. You get some lower harmonics down to 200Hz or so but not too much. There is no sense of vocals from the woofers at all crossed at 200Hz. Below 200hz is in a range with a very omni pattern too. So there is not effect of the H frame in the top octave that they cover. The reverse mounting of one cancels out some even order distortion and balances the weight of the speaker.

And if you put them on the same plan on an open baffle then you give up a lot of low frequency output.