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Commercial Gainclone kit- building instructions

Hi Peter,

yes, of course, it would be no problem to test this myself. But you see, this is the story:

A couple of weeks ago I finished my recent project, bulding a Monica USB from DIYparadise. I installed a Nelson Pass B1 Pre-Buffer at the output stage. After many weeks of testing different power supplies (smps, linear with regulation, linear without regulation, different caps of different values, rc-stages with different values for R, etc.) I build a very nice linear power supply without any regulation at all, which was clearly the best sounding solution. Then I tried some different output coupling caps. Originally, Monica comes with 4 BG N 4,7/50 in super-e configuration. But I tried other caps like russian military pio's, Teapo industrial MKP's, Mundorf MKP's and some others. Sometimes with silver mica or small mkp bypass caps, sometimes without. After about 8 weeks (!!) of testing output caps only, I decided to stay with a very special combination of a russian MBGO paper-in-oil, paralleled with Intertechnik MKP Q4's, both caps of same value.

I was convinced by the sonic result, but I also learned that testing caps easily can become a neverending story! Further more, some other caps I tested were really good, too! This time I don't want to do much testing, I just want to go for something which already had been tested and evaluated by someone who really cares about such things, and who has made the right things because of great experience and knowledge. And I thought that YOU must be this guy ;-)

Regards - martin
 
Well, I see that you are very particular about those things, in that case I can only provide some guidance as the final results will greatly depend on your taste and the rest of the system.

Generally, I don't like put caps in parallel, while certain aspects of sonic presentation seem to improve, other will suffer. I always found that naturality and intensity of the event is somehow compromised when caps are in parallel.

Still my preferred combination inGC is BG N 100/50 at the chip and BG STD in PS: N caps provide warmth, texture, image density and add a bit of emotional content (that only BG N can really do so well). BG STD are responsible for main filtration and bass extention, preferrably, I wouldn't be using them at all, but for full range response they are neccessary.

Panasonics are much more affordable solution and they actually sound very good, but they missing a bit of an intensity of N caps. Adding small bypasses on rectifier board will "inject" the N factor, but in some ways may also compromise other things, so while you be getting more warmth, texture and density, you might be loosing bass definiton, immediacy, resolution or air.

I sometimes place BG N bypas on negative rail only, which seem like a less compromised approach.
 
Peter, thanks a lot! This is exactly the guidance I need to make things much easier.
And who knows, perhaps I would have found exactly the same results as you, but not without a few weeks of struggling and testing and finally breaking up my head...

Now I can just fit in the large Panasonics and I'm done, without thinking too much about all this, just taking it "as it is"!

Thanks!

martin
 
Peter,

I have just completed construction and testing for an 8 channel set up (to power 2 Linkwitz Orion speakers which are not yet constructed).

The circuit board soldering took about 5% of the total project time. The rest has been chassis and power supply "engineering" and construction.

I am using a single 25V/25v 625VA toroid transformer to supply all 8 channels. This may or may not turn out to be a smart choice. I will know more after I have played some music. I left all 8 audio boards connected to their rectifier boards and supplied AC to all 8 rectifier boards, connecting AC1 and AC2 to each board.

I had to connect AC1 and AC2 to one set of 4 channels and then "reverse" the hookup to the other set of 4 channels. This meant connecting AC1 supply source to AC2 and supply source AC2 to AC1 on the other set of 4 channels. I don't know why this was needed to keep from blowing fuses; but once I did it all was well.

If I were not a total computer klutz I would send pictures. Maybe I can figure it out sometime in the future.

Many, many thanks to you and all the others who posted helpful text and pictures.


Joe Ewing
Las Cruces, NM
 
Gainclone construction - 8 Channel

Andrew T and Peter

I want to send pictures but at my level of computer competency there might be a little frost around hades before I am able to do it.

As far as the ground situation: I have one star ground with three connections: one from each "bank" of 4 amplifier boards and one from the power supply. ( There is no connection of the two secondary windings to anything except the circuit boards - AC1 and AC2). A total of 3 wires are running to the star ground.

I isolated each amplifier input and output from the chassis and ran ground wires from the connectors to each circuit board where Peter provided a connection point. Each amp board in a bank - left and right - is connected to the others, again as peter has shown for two boards - only I made it a total of 4 on each side. It is from those 4 connected grounds to the circuit boards that a wire was run to the star ground. See paragraph 2 above.

Thus the input and output grounds all occur at the level of the circuit boards, and from there go to the star ground.

HTH. Please ask more questions.

Thank you for your interest in my project.


Joe Ewing
 
Hello Peter, Andrew and others - i'd be very grateful for some help with an Audiosector LM4780 amp (bridged setup)...

Both channels worked fine initially on the bench - credit to the extraordinary depth of info on this forum

but, having mounted them in an aluminium roasting pan, one channel is causing the bulb tester to light up brightly.

with the amp separated from the power board, the latter is correctly giving about 32v. With the boards connected, the voltages at the outputs of the power board fall to about 8v (V+ to PG+ and V- to PG-). With the power board disconnected, the resistance between V+ and V- on the amp board is 50 Ohms.

this is without the chip being mounted on anything. The resistance between the chip's metal back and V- is 60 Ohms (it should be none?) and between the back and V+ is 45 Ohms

I can't see a short anywhere - could it be that? or have i fried the chip or another component? the other channel is set up just the same and seems fine. i haven't got any source or speakers connected. what else can i test?

any tips much appreciated!

thanks
ben
 
Hello

While i was finishing my audiosector GC i left the Rfnb for the end to solder. (as soon as i finish it i will post some pics)

I was quite busy with the cases and in the mess i lost my caddocks 22k. Trying to find in Greece caddocks or dales or something of that range i came up with nothing. Anyone know of a source online or other?

Peter any ideas?

Thanx
Nick