Want to build Nuuk's original inverting LM3875 gainclone.

[danielwritesbac]

http://myweb.tiscali.co.uk/nuukspot/...gainclone.html

That amplifier has been in audiophile service since 2003. That makes it a good baseline reference.

From previous experience, I have to regard LM3875 as a hyper revealing component that is intolerant of minor design variations. That's personal opinion, but there are also thousands of documentations on the subject.

Therefore I want to build his amplifier straight on spec.

Most of the specs are listed on this page http://myweb.tiscali.co.uk/nuukspot/...inclonesl.html but I'd like to get really, really picky, because I, personally, believe that I would otherwise not hear exactly the results as reported.

So, I'd like to ask for help.
Right away, I'm in trouble. Even if I could find the discontinued transformer, it will do differently (half the inductance ratio) when the primaries are arranged for my 115v wall outlet. Therefore, I'm in need of a "closest match" substitute. If I read correctly, the transformer from the Arcam A60 was used, and then it was replaced by two 36vct (18,0,18) transformers, details unknown except that they were preferred. Any ideas?

[Nuuk]

Dan, if you haven't twigged yet, factors such as the mains supply, and your listening environment have a much bigger affect on the sound of a chip amp, than the type of cap, resistor, or even power supply.

You must be able to find a 120VA 25v centre-tapped transformer somewhere in the USA. But what have you been using to date? Can't you try something that you already have to get up and running. Then if you are not satisfied, go out and buy another traffo. Life doesn't have to be quite so complex!

[danielwritesbac]

Hi man!! Thank you!!!

I'm so glad you're here because I'd love to hear the very amplifier that you described (hopefully at less cost than the airline ticket).

I do happen to have this transformer: http://www.alliedelec.com/Search/Pro...px?SKU=2272065

And I have a pair of these: http://www.alliedelec.com/Search/Pro...px?SKU=9288566

Or, should a use a toroid (or two?) for "closest match"?
EDIT: I've got to get some from here anyway http://www.antekinc.com/price1.html, so if one (or two?) of these is more suitable, it would save me some cost to ship in the same box.

Thanks again!

[Nuuk]

I apologise if my English isn't that clear! What I am trying to get over to you is that you won't hear the same amp that I built because too many other things affect the sound.

You don't 'hear' an amp. You hear what is coming out of the speakers and how that is affected by the room you are in, and by what is fed into the amp by the previous stage(s).

When you build that basic design, you have a starting point by which to judge other chip amp designs. But it is your starting point, as the one I built was my starting point. There is no universal ideal here!

[pacificblue]

Originally posted by danielwritesbac
Want to build Nuuk's original inverting LM3875 gainclone.

Your first solid-state amplifier, Nuuk's gainclone, the "I got bored" project in between...

Are you trying to beat destroyer X to the Guinness Book of Records for the biggest number of DIY amps?

[danielwritesbac]

Originally posted by Nuuk
I apologise if my English isn't that clear! What I am trying to get over to you is that you won't hear the same amp that I built because too many other things affect the sound.

You don't 'hear' an amp. You hear what is coming out of the speakers and how that is affected by the room you are in, and by what is fed into the amp by the previous stage(s).

When you build that basic design, you have a starting point by which to judge other chip amp designs. But it is your starting point, as the one I built was my starting point. There is no universal ideal here!

Oh, its me that wasn't clear. But, I would like to know if the amp (the one you use) is dual-mono or not.

[danielwritesbac]

Originally posted by pacificblue
Your first solid-state amplifier, Nuuk's gainclone, the "I got bored" project in between...

Are you trying to beat destroyer X to the Guinness Book of Records for the biggest number of DIY amps?

Sorry that I'm so hyper.

The "I got bored." is an older design that's getting finished up. The solid state project is because I was curious about the many available.
Almost, almost, I said "the many flavors available," but then I remembered our ROHS conversation.

Nuuk's gainclone, I want to hear, because I've never won a fight with LM3875 yet. However, the description on that page is exactly what I like it to do.

[Nuuk]

Oh, its me that wasn't clear. But, I would like to know if the amp (the one you use) is dual-mono or not.

The one I use is the one with the Resurrector, and as described in the TNT review. The subject of this thread was dual mono as clearly stated in the article!

[John C]

The subject of this thread was dual mono as clearly stated in the article!

Oooooooooooohhhhhh

Regards

JC

[danielwritesbac]

Originally posted by Nuuk


The one I use is the one with the Resurrector, and as described in the TNT review. The subject of this thread was dual mono as clearly stated in the article!

Sorry man. I was confused by the 1 transformer on the parts list. Now, I remember reading that I was supposed to double-up that list. Oh sorry. I'll go print the article and read several more times (without all that screen scrolling).

P.S. I can't find the transformer VS33L on Maplin. Is that Toriod?