GT Audio Works Planar/Ribbon Speakers and Sound Insight Open Baffle Sub Woofers

GT Audio Works

Industry Expert
Feb 12, 2015
93
53
18
58
Stockholm NJ
www.gtaudioworks.com
#1
Hi All,
Been kicking around other peoples threads, thought it was time I wrote my own.
I'm Greg the designer /manufacturer of these loudspeakers.
If anyone has any questions or comments this is the place to put 'em.
Greg
 

GT Audio Works

Industry Expert
Feb 12, 2015
93
53
18
58
Stockholm NJ
www.gtaudioworks.com
#3
Hi Greg,
I don’t want to go too far off topic in this Alsyvox thread but any chance you guys could give a bit more background on your Servo sub system (obviously in another thread if at all possible). Would love to hear your thoughts on the difference on adding additional pairs of ob woofers to the subs.
================================================================================================
Tao,
The Sound Insight subs are sold by my dealer Steve Rabitz (aka. planarman) of Sound Insight Huntington NY.
They come in self amplified stereo pairs of 2-3-4 and 6 per side.
If your room isn't too big 2 per side is more than enough.
They will play cleanly down to 16hz
3 are better and 6 are wonderfully excessive !
If you never heard the 6 per side you would be happy with 2 or 3.
But like horsepower more is always better.
6 present a wall of pressure that once heard is addictive.

At the time I met Steve he was using these subs with BG FS 880 speakers with a quite an elaborate crossover modded with Dueland goodies.
I set up my planar ribbons in his listening room next to his BG's.
3 minutes into the first demo track, Steve said, I'm selling the BG's.and he did.
I built him a pair of GTA3r's and he has been selling the combo as a system ever since.

The GTA3R speakers will hold their own just fine as a full range speaker. So why add a sub ?
Adding a good sub just imparts a sense of ease and power that has to be heard to be appreciated.
The Dipole planar and OB sub combo is a no brainer..the identical dipole radiation pattern gels perfectly, no boom or overhang. When the music calls for bass the sub is there, when the music doesn't its like the sub isnt even in the system.
Be warned the subs can reproduce LF energy at very high spl's.
If the music has sub bass content, you dont hear the bass , but you feel a pressure in your ears.
The same feeling you get as an airliner descends and the air pressure in the cabin increases , Its a weird experience.
Not good for ones hearing in the long term !!

Greg
 

GT Audio Works

Industry Expert
Feb 12, 2015
93
53
18
58
Stockholm NJ
www.gtaudioworks.com
#4
What audio shows will GTAW speakers be attending?
Being on the east coast, for now only Axpona and Capital AudioFest. I dont do New York any more...it's usually the week before or after CAF.
For me it makes more sense to exhibit at CAF...I get a big room for the same money a shoe box costs in NYC.
Maybe the new show in Fla. next year, we will see.
Big speakers are hard to transport, so I doubt you will see me out at shows like RMAF or on the west coast.
Sometimes I wish I had designed cables or headphones..hop on an airplane with a carry on and you're ready to show you're products.
Greg
 

the sound of Tao

Well-Known Member
Jul 18, 2014
1,258
691
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#5
Hi Greg,
Thank you. I do love ribbons and have Maggie 20.7s and am very appreciative of the virtues of full range ribbon based bass. I’ve always struggled to get subs that are seamless for a dipole speaker but like the notion of these OB subs.

I also have OB based Trio Pap horn speakers with 2 x 15 inch OB woofers per side but I have only driven them so far with a SET amp but for me the horns are great for everything I play short of dance music.

I’m not chasing home theatre style bass (and I also enjoy my hearing) so have been thinking of a couple of options but am also drawn to your GTA3R ribbons at any rate. Crossover-less high sensitivity ribbons are a very appealing idea for me as a confirmed SET addict.

I do also have Harbeth 40.2s and they have a touch of slam that clearly neither the Pap horns nor the Maggies quite do and that slight box slam for me is perfect for some music but in every other way the Pap horns and big Maggies can do things the Harbeths just can’t simply approach.

So the larger 3/4/6 OB subs can clearly go very low and I’m figuring they also energise the room more as they get more drivers per side and obviously they can also go louder but is there any more slam at all say from 3 drivers a side sub versus 2 or do you think slam is more a box thing than an OB bass quality. Hope that question makes sense.

Cheers
Tao
 
Last edited:
Apr 30, 2017
29
12
8
#6
Hi Tao
The servo subs that we utilize are completely different than any other - without getting to technical the concept is that the woofers are not to heavy which results in nimble articulate bass but have the ability to play down low and produce high SPL’s due to the very large motor structure.
The servo technology utilized Is the very best in the industry. Each woofer has its own individual wired connection directly to the servo on board computer - the effect is
that each woofer is individually controlled by the servo circuit which controls the excursion of the X max to within unmeasurable limits Which in turn produces no bloat or overhang and can keep up with the planar driver. They measure to 15hz.
 

allvinyl

Active Member
Apr 10, 2013
261
36
28
68
Burnsville, MN
#8
Hi Greg,
Thank you. I do love ribbons and have Maggie 20.7s and am very appreciative of the virtues of full range ribbon based bass. I’ve always struggled to get subs that are seamless for a dipole speaker but like the notion of these OB subs.

I also have OB based Trio Pap horn speakers with 2 x 15 inch OB woofers per side but I have only driven them so far with a SET amp but for me the horns are great for everything I play short of dance music.

I’m not chasing home theatre style bass (and I also enjoy my hearing) so have been thinking of a couple of options but am also drawn to your GTA3R ribbons at any rate. Crossover-less high sensitivity ribbons are a very appealing idea for me as a confirmed SET addict.

I do also have Harbeth 40.2s and they have a touch of slam that clearly neither the Pap horns nor the Maggies quite do and that slight box slam for me is perfect for some music but in every other way the Pap horns and big Maggies can do things the Harbeths just can’t simply approach.

So the larger 3/4/6 OB subs can clearly go very low and I’m figuring they also energise the room more as they get more drivers per side and obviously they can also go louder but is there any more slam at all say from 3 drivers a side sub versus 2 or do you think slam is more a box thing than an OB bass quality. Hope that question makes sense.

Cheers
Tao
Hi Tao,
I feel the integration of the OB subwoofer with the panel is seamless. I went with the two driver per side system because that level of energy is appropriate for my room. Though the room is essentially 18 ft by 36 ft I have a low 7 foot 2 inch suspended ceiling. I can crank it up and get the volume and bass I want without overloading the room. I heard the six driver per side system at Steve's, but knew that would be too much for my room, though it is a lot of chest thumping fun. :) See you at Axpona?
 

the sound of Tao

Well-Known Member
Jul 18, 2014
1,258
691
113
#9
John,
Thanks for that feedback on the subs integration. The subs I tried to get to marry up with the Maggie 20.7s were either 10 inch, 12 and 15 inch and while the Wilson Benesch Torus came closest none of them really quite kept up. Admittedly I am a fair bit of a coherence-aholic. When I tried with 250 watt valve monos on the 20.7s and then the blending to sub was generally much better as the mid bass fullness covered over the transition better. But am thinking in my case with the potential of running a good SET amp for the panels and then also with the subs being dipole (with the shared radiation characteristics) I could see how it could actually get seamless. I think my early approach was just wrong with trying to get a match with a relatively neutral (not quite lean but almost) SS amp on the main speaker that helped also expose the transition when I tried to pair to a much fuller mosfet on the sub.

I figure you are still getting the hours up with burning in the panels and seems the last thing that comes is full bass extension and control but have you tried the GTA3R as a full range panel on their own. Also dialling in the speakers and subs would be fun. It takes me more time with panels than any other speakers and factor in your subs as well and I figure you could almost have a rubiks cube worth of combinations to work through.

PS unfortunately won’t make it to Axpona as I come from way over on the other side of the pond and I did all my speaker spending quota this year on the PAP horns and the Harbeths... but maybe next year tho.
 
Last edited:

allvinyl

Active Member
Apr 10, 2013
261
36
28
68
Burnsville, MN
#10
John,
Thanks for that feedback on the subs integration. The subs I tried to get to marry up with the Maggie 20.7s were either 10 inch, 12 and 15 inch and while the Wilson Benesch Torus came closest none of them really quite kept up. Admittedly I am a fair bit of a coherence-aholic. When I tried with 250 watt valve monos on the 20.7s and then the blending to sub was generally much better as the mid bass fullness covered over the transition better. But am thinking in my case with the potential of running a good SET amp for the panels and then also with the subs being dipole (with the shared radiation characteristics) I could see how it could actually get seamless. I think my early approach was just wrong with trying to get a match with a relatively neutral (not quite lean but almost) SS amp on the main speaker that helped also expose the transition when I tried to pair to a much fuller mosfet on the sub.

I figure you are still getting the hours up with burning in the panels and seems the last thing that comes is full bass extension and control but have you tried the GTA3R as a full range panel on their own. Also dialling in the speakers and subs would be fun. It takes me more time with panels than any other speakers and factor in your subs as well and I figure you could almost have a rubiks cube worth of combinations to work through.

PS unfortunately won’t make it to Axpona as I come from way over on the other side of the pond and I did all my speaker spending quota this year on the PAP horns and the Harbeths... but maybe next year tho.
Hi Tao,
Thanks for the detailed update on your subwoofer experiences. I agree with you about coherence. I think a big part of the equation that allows the SI subs to work well with the panels is the variety of controls on the servo amps. I am a complete novice when it comes to changing the amp settings to help with the integration. I have previously only ever worked with the speaker and the room. Having the additional flexibility to make several adjustments on a subwoofer amp does, as you write, help to create a rubiks cube of combinations to sort through. Fun? Yes, but I can see this is going to be an ongoing arduous process that will have both frustration and reward.

Yes, logging hours is helping with break-in and the new line stage is yet another factor. Another point you brought up; that of different amplifier types is something I am also thinking about now. My current Viola Symphony is class A/B. I am anxious to try the 60 watt class A Pass amps that I heard in NJ. I've not been able to get current delivery stats out of Viola and I wanted to compare the Symphony current delivery capabilities to that of the Pass amps. I believe the Pass output is 30 amps. If anything would cause stridency or perceived strain it might certainly stem from the amp running out of gas just when it needs the headroom.

I understand completely about not coming over for the show. I have for years been trying to justify going to Munich. I might never get the chance since BMW bought the MOC so it looks that show might be going back to Frankfurt(where it started I believe). Do you have any insight on this?

John
 

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the sound of Tao

Well-Known Member
Jul 18, 2014
1,258
691
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#11
Thanks for that John, I have a mate who is heading over to Munich so I mentioned to him to keep his ears open about the future of hiend returning to Frankfurt so if he hears anything while over there he’ll let me know.

We also spoke today about options for subs so am starting to get my head around what I might start looking for. I like researching for a while so just under way now really.

If your GTA3Rs are like all the other ribbons I’ve heard they will be super critical of anything in the system but especially the amp that is powering them. So amp upgrade could be interesting tho the Viola amps I’ve heard were really nice.

Cheers
Tao
 

spiritofmusic

Well-Known Member
Jun 13, 2013
8,459
860
113
E. England
#12
Tao, why subs w your PAP Horns1?
Aren't four 15" OB woofers enough in your room?
 

GT Audio Works

Industry Expert
Feb 12, 2015
93
53
18
58
Stockholm NJ
www.gtaudioworks.com
#13
Eric of Zanden Audio was nice enough to stop by yesterday and set up the system we will be showing at Axpona in Steve's listening room.
Push pull pair of KR845 tubes 60 wpc class A. makes a good match with speakers and subs.
Punchy, dynamic, amazing soundstage.
Very happy with the setup...looking forward to the show
Greg
 

allvinyl

Active Member
Apr 10, 2013
261
36
28
68
Burnsville, MN
#14
Eric of Zanden Audio was nice enough to stop by yesterday and set up the system we will be showing at Axpona in Steve's listening room.
Push pull pair of KR845 tubes 60 wpc class A. makes a good match with speakers and subs.
Punchy, dynamic, amazing soundstage.
Very happy with the setup...looking forward to the show
Greg
Great job guys! Looking forward to meeting Eric at the show.
 

Bodhi

Well-Known Member
Apr 20, 2014
824
250
63
Melbourne, Australia
#17
John, thanks for posting the videos! Fyi, the first video is coming up as 'unavailable', so there might have been a copyright claim, or the video may need to be uploaded again.

Straight out of the box, they're sounding musical and dynamic as far as I can tell through my pc's speakers. They also look beautiful. With further breakin the they should open up even more and sound a bit more refined and smooth. How many hours do you have on them so far?
 

cjfrbw

Well-Known Member
Apr 20, 2010
2,314
111
63
Pleasanton, CA
#18
Do you guys have detailed pictures of the back of the speakers and the binding post areas?
 

the sound of Tao

Well-Known Member
Jul 18, 2014
1,258
691
113
#19
Tao, why subs w your PAP Horns1?
Aren't four 15" OB woofers enough in your room?
Apologies Marc, missed this earlier.
Just exploring some ideas, still early days. May or may not. I also explored this pathway with the Maggie 20.7s back a few years ago but ultimately got everything I needed from bass sans subs.

I also very much love the notion of high sensitivity cross-overless ribbons as well so enjoying reading and understanding on how the GTA3R works.
 

GT Audio Works

Industry Expert
Feb 12, 2015
93
53
18
58
Stockholm NJ
www.gtaudioworks.com
#20
Do you guys have detailed pictures of the back of the speakers and the binding post areas?
My personal pair is not the current configuration it uses an outboard box which gives me the ability to change resistor values on-the-fly at shows.
Currently I use two sets of binding post made by cartas for bi wiring if one wishes. Maybe John can do me a favor and take a picture and post it to show you
But if you want a specific connection Hardware let me know I can use anything you want
 

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