Carl: Mine isn't working right, despite being exactly the same component values as put forth by metalman. I've tried with a pair of LM3886's per channel, and a pair of LM4780's (with the two amps per chip on the 4780 paralleled) and the same troubles.
So, I've either goofed (entirely possible) or, um... goofed. I don't see any other option, unless my PCB layout sucks royally in a way I never thought possible.
I have simply not had any time available to troubleshoot it more recently - after this weekend I think I will again have some time for it. I need to order more parts to do some experimenting as well - I want to step back to making sure I can do a standard by-the-spec-sheet amp on the PCB's I've designed without problems. From there I'll step into integration with the SuSy circuit.
I'm pretty sure Russ started out with Metalman's values, then went off an introduced a completely new variant that may not really fall into the SuSy camp(?) or maybe it's just not in line with Nelson's prompt.
C
So, I've either goofed (entirely possible) or, um... goofed. I don't see any other option, unless my PCB layout sucks royally in a way I never thought possible.
I have simply not had any time available to troubleshoot it more recently - after this weekend I think I will again have some time for it. I need to order more parts to do some experimenting as well - I want to step back to making sure I can do a standard by-the-spec-sheet amp on the PCB's I've designed without problems. From there I'll step into integration with the SuSy circuit.
I'm pretty sure Russ started out with Metalman's values, then went off an introduced a completely new variant that may not really fall into the SuSy camp(?) or maybe it's just not in line with Nelson's prompt.
C
Hi Carl,
I have two amps made which are both truly super symmetrical, they just use different techniques to get there.
The first uses metalman's schematic pretty faithfully, the other has a thread of its own now.
I have to say that both sound excellent, but that the newer circuit is better behaved in terms of offset and such. No turn on or turn off issues, and it seems to run a bit cooler.
You can read about that amp here:
http://www.diyaudio.com/forums/showthread.php?postid=940344#post940344
Cheers!
Russ
I have two amps made which are both truly super symmetrical, they just use different techniques to get there.
The first uses metalman's schematic pretty faithfully, the other has a thread of its own now.
I have to say that both sound excellent, but that the newer circuit is better behaved in terms of offset and such. No turn on or turn off issues, and it seems to run a bit cooler.
You can read about that amp here:
http://www.diyaudio.com/forums/showthread.php?postid=940344#post940344
Cheers!
Russ
Some of you may find this interesting:
http://www.diyaudio.com/forums/showthread.php?postid=949032#post949032
http://www.diyaudio.com/forums/showthread.php?postid=949032#post949032
SuSy OPAMP Preamp
Hi Metalman (aka Terry) & Russ [Mr. Pass]:
I am curious to know if you think the same type of design concept could be applied to build a line-level preamp -- when I first saw Nelson's schematic, I thought I was looking at a design for a pre, not power amp.
If you guys find this interesting/feasible, I would be most interested in seeing a schematic -- or I guess I will just have to learn enough about eagle to do it myself.
I use Linkwitz Orion’s, and have recently built a simple OPA2134 based pre-amp [actually the Hagtech Oboe] to use with the Linkwitz ASP/'crossover -- which some fantastic synergistic results -- 5x OPA2134 in Oboe [one really] driving 11 x OPA2134 in the ASP. Using this while I work through my (twisted.) CSS BoSoZ. Could one simply swap out the LM3XXX for a set of OPA134 and get a super symmetric line-level pre? Forgive me if this sounds ignorant....
Fantastic work from you both - we [the DIY community] own you (and of course Nelson) a large debt of gratitude. Thanks from the southern hemisphere.
--Charles
Hi Metalman (aka Terry) & Russ [Mr. Pass]:
I am curious to know if you think the same type of design concept could be applied to build a line-level preamp -- when I first saw Nelson's schematic, I thought I was looking at a design for a pre, not power amp.
If you guys find this interesting/feasible, I would be most interested in seeing a schematic -- or I guess I will just have to learn enough about eagle to do it myself.
I use Linkwitz Orion’s, and have recently built a simple OPA2134 based pre-amp [actually the Hagtech Oboe] to use with the Linkwitz ASP/'crossover -- which some fantastic synergistic results -- 5x OPA2134 in Oboe [one really] driving 11 x OPA2134 in the ASP. Using this while I work through my (twisted.) CSS BoSoZ. Could one simply swap out the LM3XXX for a set of OPA134 and get a super symmetric line-level pre? Forgive me if this sounds ignorant....
Fantastic work from you both - we [the DIY community] own you (and of course Nelson) a large debt of gratitude. Thanks from the southern hemisphere.
--Charles
Hi Charles,
You may find this circuit interesting..
http://www.diyaudio.com/forums/showthread.php?postid=921115#post921115
It is a 'super symmetrical' preamp by virtue of its use of the THS4131 which licensed the IP from our estemed friend and benefactor Nelson Pass.
It may do the job for you nicely with 150ma of maximum drive.
Cheers!
Russ
You may find this circuit interesting..
http://www.diyaudio.com/forums/showthread.php?postid=921115#post921115
It is a 'super symmetrical' preamp by virtue of its use of the THS4131 which licensed the IP from our estemed friend and benefactor Nelson Pass.
It may do the job for you nicely with 150ma of maximum drive.
Cheers!
Russ
SuSy Pre
Thanks Russ:
Saw that -- (actually sent you a message via twisted pear to see when this will be available in KIT form) -- so... it would be fairly straight forward to apply the OPA134 in the place of the output amps? Would make for a VERY clean little board I would think, and if just listening to a straight-up OPA2134 is any indication, would be fabulous. I will definitely have to try this.
--Charles
Thanks Russ:
Saw that -- (actually sent you a message via twisted pear to see when this will be available in KIT form) -- so... it would be fairly straight forward to apply the OPA134 in the place of the output amps? Would make for a VERY clean little board I would think, and if just listening to a straight-up OPA2134 is any indication, would be fabulous. I will definitely have to try this.
--Charles
For those interested, gerber files for the layout i did can be found here: http://ruffneck.net/pages/posts/xgc-or-xed-gainclone12.php
BR,
Kari
BR,
Kari
lukio said:Dear CJD,
I thougt your amp get oscillation, may be this compensation give more stabilization for the XGC amp.... But I don't built this amp yet, just simulation...
cheers
Lukio
I think you're right about what's going on.
I've got more parts and an almost finished X-BOSOZ (grounding issue remains - why is it *always* grounding). Thank you for the contribution! I'll be starting by testing the basic amp boards I have (which can be built for the X-GC or for a standard GC) just to make sure that's not the root of the issue. From there I'll revisit the rest, and see where it goes. I got a good deal on some used monoblocks in the mean time that I'll be using till these are ready, so less pressure. As if over a year can equate to pressure. 
Back to work!
I want to use IC(lm3886, lm3875) to build a amplifier,
and I found four balance circuits :
1. SuperSymmetry of Nelson Pass
http://www.passlabs.com/downloads/articles/susy.pdf
2. A output topology based on a design by George D Pontis
http://www.forsselltech.com/downloads/schematics/BalOut1.pdf
3. Ultra Symmetry of wensan
http://www.diysong.com/images/ultras/UltraSymmetryPreAMP.htm
4. Balanced Line Driver with Floating Output
http://sound.westhost.com/balance.htm#input-improve
I am freshman, and need help.
Can anyone explain which one is better and why?
and I found four balance circuits :
1. SuperSymmetry of Nelson Pass
http://www.passlabs.com/downloads/articles/susy.pdf
2. A output topology based on a design by George D Pontis
http://www.forsselltech.com/downloads/schematics/BalOut1.pdf
3. Ultra Symmetry of wensan
http://www.diysong.com/images/ultras/UltraSymmetryPreAMP.htm
4. Balanced Line Driver with Floating Output
http://sound.westhost.com/balance.htm#input-improve
I am freshman, and need help.
Can anyone explain which one is better and why?
Attachments
Wye do you need a balanced input? Are you in a studio with several meters of signal cable?
If the circuit is for the input I think it’s to complex solution for signal handling for High end.
Make everything as simple as possible for nice sound. Use good components and transformers it’s more imported.
If the circuit is for the input I think it’s to complex solution for signal handling for High end.
Make everything as simple as possible for nice sound. Use good components and transformers it’s more imported.
BrightXA said:
2,3 and 4 are essentially the same circuits, implementing
balanced operation of opamps. 2 and 3 take feedback off both
the local and opposite outputs.
Circuit 1 does not use conventional op amps, and so the diagram
is a bit misleading in that regard. You cannot directly use an
LM3886 or similar chip.
They all work, but the performance is dependent on the specifics
of the execution.
Hi Mr. Pass,
Can you help to explain why circuit 1 cannot be implemented with LM3886 opamp? I have build a similar amp but with two non-inverting configuration ala differential I/O intrumentation configuration and it fail to work. I did not investigate further. Would appreciate if you can shed some light on this configuration.
Thanks.
Can you help to explain why circuit 1 cannot be implemented with LM3886 opamp? I have build a similar amp but with two non-inverting configuration ala differential I/O intrumentation configuration and it fail to work. I did not investigate further. Would appreciate if you can shed some light on this configuration.
Thanks.
It's not an op amp.
What you see as the (+) terminal on the diagram is a low
impedance input, not the high impedance input you expect on
an op amp. Think of that stage as if it's a "current feedback"
amplifier, but with the output phase inverted.
You can't wire a chip amp this way and have it work.
What you see as the (+) terminal on the diagram is a low
impedance input, not the high impedance input you expect on
an op amp. Think of that stage as if it's a "current feedback"
amplifier, but with the output phase inverted.
You can't wire a chip amp this way and have it work.
Hi Mr. Pass,
Is it because +ve input for conventional opamp would be floating with circuit 1?
Attached is the instrumentation configuration with LM3886. It does not work. I assume that the differential signal passing through R1 e.g. 2K will somehow provide some virtual ground by splittting it into 1K-virtual gnd-1K. BTW does this circuit have the supersymmetric noise cancellation via R1?
Thanks.
Is it because +ve input for conventional opamp would be floating with circuit 1?
Attached is the instrumentation configuration with LM3886. It does not work. I assume that the differential signal passing through R1 e.g. 2K will somehow provide some virtual ground by splittting it into 1K-virtual gnd-1K. BTW does this circuit have the supersymmetric noise cancellation via R1?
Thanks.
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