High-End Regulated Buffered Inverted GC

[Peter Daniel]

Originally posted by t.
No Probs Carlos

I am using Pedja's Buffer with the regulated amp/clone/mini-Krell and it sounds great, if it wasn't for people like you guys I would still have my standard non inverted GC gathering dust in my parts box

Your enthusiasm reminds me of another English guy, who was also very excited about tube buffered GC, in times when JR inroduced his circuit. If it wasn't for that enthusiasm, I would be probably still delaying building the 'Mini Krell'. Well, after hearing that you can virtually sweep the floor with the other amp, I couldn't take it anymore and decided to built one as well.

[carlosfm]

Everybody was having "Non-inverted fun" and i reported this:
http://www.diyaudio.com/forums/showt...ht=#post272320

Unfortunately, (unbuffered) non-inverted was the mood then and it seams it still is now.
At the time nobody cared about a freak still insisting in IGC, and op-amps or whatever as a buffer was a crime for the minimalists.
Much before this I had reported huge improvements with my pre, and insisted that the GC benefits from a good pre.
After that I tested NIGC, BNIGC and it's good, but not like this.
I tested LM3875, LM1875, LM3886, LM4780, OPA548, OPA549.
What I have on my main system is the best combination (of course ), and it's exactly what I reported here: Inverted LM3886 + NI OPA627 buffer + regulated PSU.
The regulated PSU I used first when i made my sub (2//OPA549), and I searched the net for suitable regulators.
I've searched TI, National, LT, On, AD, etc...
I downloaded the datsheets for the LM338 and LT1083 and it seamed fine for the job (I didn't find any good negative reg).
I did the sub, with LM338 (the LT I didn't find here) and the results were very good.
I later found out that Pedja was into this already, and even had a schematic on his site.

Then I regulated my amp, several tests with caps, listening tests, etc. and it was the final touch.

mini-Krell.

[Peter Daniel]

It's exact replica of Carlos circuit, with special attention to using the average quality parts. I hated installing the regulators I removed from ML preamp, but if it works for Carlos, it will surely work for me. I modified Brian's board and mounted regulator's boards in place of the caps. Another board with OPA627 is mounted between the regulators. I took special care not to exceed the minimum recommended distance between 33u bypass caps at LM3875.

Al in all, it took me almost 10 hours to built that amp. It better be as good, as Carlos claims. It's inverting, BTW.

[leadbelly]

Originally posted by Peter Daniel
Al in all, it took me almost 10 hours to built that amp.

Freak.

[Nuuk]

Al in all, it took me almost 10 hours to built that amp.

That's where you are going wrong Peter! You need to let these things mature over a couple of months like I do!

[Peter Daniel]

Originally posted by Nuuk


That's where you are going wrong Peter! You need to let these things mature over a couple of months like I do!

I assume you are still waiting for your regulators

[Peter Daniel]

Originally posted by carlosfm
Everybody was having "Non-inverted fun" and i reported this:
http://www.diyaudio.com/forums/showt...ht=#post272320

Unfortunately, (unbuffered) non-inverted was the mood then and it seams it still is now.
At the time nobody cared about a freak still insisting in IGC, and op-amps or whatever as a buffer was a crime for the minimalists.
Much before this I had reported huge improvements with my pre, and insisted that the GC benefits from a good pre.

To me the eye openening was this thread: Y'all will love this! / All chipamps on one table!

If 47Labs Shigaraki could be better than both JLTi and AMP-1, I was suspecting that inverted topology was not up to the task. After building first NI amp we knew right away that the deficiencies we were experiencing so far, were more or less gone. I also sent a conversion kit to Void, and he reported an improvement as well.

IMO, the NI amp actually benefits more from the preamp than an invering. The preamp doesn't have to be exactly at the amp's input. Using average length cables doesn't do anything to reduce the effect.

I tried quite a few preamps, but most of them were worst than a volume control mounted directly at the inputs. It's only with a really good preamps, that the amp begins to truly sing. And when it does, you know you're on a right path.

Now back to testing mini krell. It's quite an advanced circuit and I hope I have my wiring OK

[t.]

Originally posted by Peter Daniel


Your enthusiasm reminds me of another English guy, who was also very excited about tube buffered GC, in times when JR inroduced his circuit. If it wasn't for that enthusiasm, I would be probably still delaying building the 'Mini Krell'. Well, after hearing that you can virtually sweep the floor with the other amp, I couldn't take it anymore and decided to built one as well.

I have listened to the valve buffer and didn't like it.
My minimal non inverted clone used 1000uf BG caps, caddock resistors in the fb etc, ok it wasn't bad but to my ears the J-fet, regulated version beats the crap out of it, it also cost me less than what I paid for two of the 1000uf BG caps.
If you prefer the non inverted minimal clone then thats fine. you can stick to throwing expensive parts in it, thats up to you.
I know which version I'll be sticking with

[Peter Daniel]

Originally posted by t.

than what I paid for two of the 1000uf BG caps.

But you were using 4 of those caps, right?

And what are the speakers that you use?

[t.]

Originally posted by Peter Daniel


But you were using 4 of those caps, right?

Yes, directly on the pins

And what are the speakers that you use?

IPL S3tlm Ribbons