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Old 27th December 2018, 04:31 PM   #51
Russ White is offline Russ White  United States
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Quote:
Originally Posted by asuslover View Post
“Stressing the board” ? I was thinking that you will eventually replace those lm3886 chips with one lm4780 . I do like the way you used the board though . I am a big fan of the lm4780 chips, I tried a lot of boards , but not the sympatico.
I am curious why mr White Russ stoped offering this: http://www.twistedpearaudio.com/docs...tpm-lm3886.pdf
Actually because of the way the OP1632 dominates this circuit using two LM3886 should work out very very well - in some ways maybe better than a single LM4780.

As to why we didn't continue with the TMP/TXD idea was just simply that Sympatico was a tighter solution with less cost and effort. Also one of the design goals of the old TXD/TPM scheme was to be able to parallel TPM modules - and in practice that was very hard to keep stable. All in all though - the idea was fun and in many ways still feasible.

This morning I did this:

Any thoughts?

Cheers!
Russ
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Old 28th December 2018, 12:25 AM   #52
asuslover is offline asuslover  Romania
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Sympatico amplifier - impressions?
Looks good, I would leave a little more space between the 2 lm3886 for better cooling and to fit decoupling caps for each chip/each rail.
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Old 28th December 2018, 03:01 AM   #53
francolargo is offline francolargo  United States
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Originally Posted by asuslover View Post
I am curious why mr White Russ stoped offering this: http://www.twistedpearaudio.com/docs...tpm-lm3886.pdf
The photo below shows the TPM/TXD modules that came off of the heatsinks onto which the current Sympatico mod boards were attached. My TPM/TXD amps served very well and gave me years of pleasure. When the DIY bug bit to upgrade, I built an Aleph J. It sounded great but was just not a good fit as my system evolved - sooo much heat! So my next amp project was a new Sympatico, which was very pleasing and very comparable in sound to the Aleph J (with my drivers). Comparing my builds and uses, Sympatico (w/ 4780 & 45K uF capacitance/channel in the PS) is noticeably more refined than the TPM/TXD amps with their 3886s. ...and just last weekend I could hear an immediate improvement in the >2kHz band with the Sympatico/3886 vs. the TPM/TXD. BTW, both new channels showed only 12 mv DC out on first cold startup.

Re: Russ' musing, I seriously thought about adding extra decoupling caps on the little 3886 adapter boards! I recall reading about 10 years ago that decoupling directly to the power pins of 3886 gainclones helped eliminate some noise. But I finally ruled it out for a number of reasons, among them my pleasure with my alredy-running Sympatico and the fact that the adaptation was an experiment.

All the best,

Frank
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Old 26th February 2019, 10:24 PM   #54
francolargo is offline francolargo  United States
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Originally Posted by Russ White View Post
Actually because of the way the OP1632 dominates this circuit using two LM3886 should work out very very well - in some ways maybe better than a single LM4780.
Sadly, a nasty electrostatic discharge from my hand zapped the experimental Sympatico/3886 into silence. It happened as I was turning the power off while the air was extremely dry.

So... Worth trying to repair? Power rails seem ok. Since both channels are gone, I suppose we could assume the same component(s) failed on each side. Any speculation re which would be most susceptible, or suggestions re diagnosis would be much appreciated. I'm willing to replace anything except the 3886s, which are so 'in there for good' that I wouldn't bother.

TIA for any help!

Parenthetically, it could have been worse! But repairing stuff is not as nice as listening to music, so I'll also isolate the entire system from ESDs. All controls - including power - will soon be managed by wifi remote.
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Old 9th March 2019, 04:00 PM   #55
francolargo is offline francolargo  United States
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Originally Posted by francolargo View Post
Sadly, a nasty electrostatic discharge from my hand zapped the experimental Sympatico/3886 into silence. ...
I'm willing to replace anything except the 3886s, which are so 'in there for good' that I wouldn't bother.
It seemed the damage could have been in the 3886s so I started over, this time with more confidence in the quality of the outcome. I was about to start making some custom chip adaptor boards but then it struck me that I could re-work some of the retired boards. ...can hardly wait to power these up!

Frank
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Old 19th March 2019, 05:41 PM   #56
francolargo is offline francolargo  United States
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...can hardly wait to power these up!
A quick note to say 'mission accomplished'. Thanks, Brian, for helping me past a brain-freeze.

The Sympatico-3886 is a nice amp! My woofers are clearly playing tighter and with more control - especially 'cranked'. My other LM4780 Sympaticos are on 32V rails but this one is getting 36.5V. I tweaked the gain from stock to ~14x per side, but also added an extra 20mF capacitance to each power rail. I like that the re-purposed adaptor boards give each 3886 its own decoupling caps (note the nice inscription on the back ). The gray Vishay .22uf film decoupling caps are a personal favorite that I've used in my other Sympaticos as well.

Cheers!
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Old 19th March 2019, 05:55 PM   #57
BrianDonegan is offline BrianDonegan  United States
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Sympatico amplifier - impressions?
FYI: There is a revision of the Sympatico in the works to use currently available chips.
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Old 20th March 2019, 01:45 PM   #58
francolargo is offline francolargo  United States
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I look forward to the product! As I was cutting the DC servos off of the old TPM boards for this amp, I was wondering... Would a really tight and symmetrical surface mount layout be enough to make parallel power chips 'play nice' together? The old TXO-4 concept but 'brilliantly executed in SMD'?
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Old 12th August 2019, 11:21 PM   #59
rickmcinnis is offline rickmcinnis  United States
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Would that mean the current SIMPATICO for sale at your site is this revision?

I was wondering if there is a reason to not bypass the input ICs if you have a device with a balanced output?

Thanks,
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Old 14th August 2019, 05:17 PM   #60
rickmcinnis is offline rickmcinnis  United States
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I ordered a single channel to see how it sounds. Will get a second if it works better.

Will use it to power an EDGAR SEISMIC subwoofer. Have been using a cheap class D amp - a Peavey/Crest that just seems to sound a little funny. Figure this will have to do better.

Using a XILICA XP2040 to drive the amp. Would like to bypass those (seemingly) superfluous input buffers unless you tell me NOT to do it. Figure it would be easy enough to remove R1 and 2 - use a leaded resistor connected to the input pad and the cable to the other. I really hate the idea of superfluous stages until I am told what their purpose is.

Let me know, please.
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