My "audiophile" LM3886 approach - Page 12 - diyAudio
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Old 19th July 2005, 05:54 PM   #111
troystg is offline troystg  United States
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Ahhhh, I see said the blind man....

Sorry, I thought you meant the opamp. Short sighted on my part.
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Old 19th July 2005, 06:09 PM   #112
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Hi all,
How to have said various turned in the thread, this circuit is a lot of nonelementary ( even if with little components ).
The matter of the "thump" is not easily that can be managed because there are 2 Opamp nesting with common NFB, and LM3886 is in configuration to bridge. The mute of LM3886 is unusable, because LM318 would go to clipping for follow the LM3886 STBY.

I have recommended to Russ to follow more possible my layout of the circuit to avoid problems of: oscillations and Ground loop.

The matter of the external Hi-cap doesn't exalt me because sets the "endless" problems described in the Thread " snubber yes or not " but it is a personal choice.
Naturally all am clear of interprets to like them my circuit, but in my layout it is "hidden" different years of technical "analysis"...

ciao

Mauro
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Old 19th July 2005, 07:31 PM   #113
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I see the 14 volt relay for the output. Is there an issue using it to handle the turn on thump?
I do not like the thumps, several amps built have switches on the outputs to allow stabilization then turning on. I use double throw with 15 ohm rsistors on one side for loading and speaker connection on other. A realy is much better, no hassle.

George
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Old 19th July 2005, 07:57 PM   #114
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The existing relay switches the speaker output grounds and prevents turnon and turnoff thumps. Does a great job.
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Old 19th July 2005, 08:41 PM   #115
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Yes, Mauro's layout with the relay handles this quite nicely. I will add the same circuit to my layout as well, only for a single channel. I was really planning to all along. I was just not sure if I would do it on the same board or as a seperate board (maybe on the PS). I think now what I will do is a single channel complete with PS on a single board. I will try to emulate Mauro's star ground on the board, I see how he brings seperate ground traces together right between the large caps on his PCB design. I will do the same.

Hopefully I will have something to look at soon.

Really I am just doing this for my own pleasure, so if it is not useful to anyone no harm done.

Cheers!
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Old 20th July 2005, 12:40 AM   #116
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Default Lots of help

Russ,
I for one look forwrd to building an amp with these boards. I have not looked closely at what is on the boards. Guess the relays will either be off board or it will be a mechanical switch to do this.

George
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Old 20th July 2005, 01:17 AM   #117
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Hi George,

I still have a lot of work to do on the layout. My intention is to use all of the same techniques Mauro did to the best of my limited ability.

The only major defference will be that my board will be for a single channel monobloc. The reason is because I want to facilitate multi channel amps (such as 5.1).

Cheers!
Russ
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Old 20th July 2005, 01:36 AM   #118
Mark Kravchenko --- www.kravchenko-audio.com
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Default Buzz a buzz buzzz

Tis a fly looking on. Keep it up!

Mark
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Old 20th July 2005, 04:11 AM   #119
troystg is offline troystg  United States
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Quote:
Originally posted by Russ White
...Really I am just doing this for my own pleasure, so if it is not useful to anyone no harm done.
Cheers!

Russ, your doing a great job, and attraching flies, myself included.

I will make suggestions so you, and Mauro, please feel free to continue slapping my hand as needed.

Mauro- Beautiful concept. I can't wait to hear it.
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Old 20th July 2005, 05:28 PM   #120
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What do you think about using CarlosFM's Snubber 1.1 power supply in place of mauro's power supply? I am sold on the advantages of regulated over unregulated, but not sure if it will change the dynamics.

Click the image to open in full size.
taken from LM338 regulated snubberized PSU for audio amplifiers
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