Dartzeel amp schematic - build this?

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#2,341
If the bulb lights up supply voltage will go down. If the bulb is still on after a moment it is a hint for
excess current in the secondary circuit. Even with reduced voltage you can measure at certain points.
If the problem is on both channels check and operate them separately (disconnect the other board).
 
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#2,344
Hello. I managed to start the amplifier, the cause was mismatched 15033/32 transistors (that's what I had). I bought a dozen or so more pairs, with the T-7 meter I managed to match them. I'm waiting for the delivery of the DY294 meter. If precise pairing fails, I'll replace it with other transistors. Thanks for the tips and time
 
#2,348
padamiecki said:
It was exactly my point until I built and listened to it
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... and now, after you built it? Have you changed your view?
Let me just remind you that "Stereophile" admitts the original NHB-108 has <1% THD, which is horrendous value, and then boasts with zero "temporal distortion". Please, note that "temporal distortion" isn't defined technical term and it has no meaningful unit. It originates from psychology. How they measure it? Do they use that term just for marketing purposes?
I have also built a NHB-108 and also have my opinion.
 
#2,350
guys,
I can see that you are Dartzeel haters ;-)
I built several classic gnfb amps, even similar to Crown,
after I heard dartzeel they went to the basement,
I can only confirm, Dartzeel measures bad, sounds wonderful to me, no distortion can be heard.
BTW this Studer is gnfb, similar but different beast.
 
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#2,352
There's an interesting review of a clone here:

Judging by the comments, people rather like it!
Judging by the price, it's probably not a bad idea to buy one and fettle it into DIYdom, rather than buying all of the separate bits 🙂

I'm not a big fan of GNFB, and I also know how clean and open something can sound without it - so I'm not surprised that it's controversial 🙂.

It's still got some feedback anyway, the thing is we don't have feedback of the speaker cones or the air, we have feedback from the speaker terminals - so the NHB-108 just pushes that feedback point back behind the followers... 😀
 
#2,354
Globulator said:
There's an interesting review of a clone here:

Judging by the comments, people rather like it!
Judging by the price, it's probably not a bad idea to buy one and fettle it into DIYdom, rather than buying all of the separate bits 🙂

I'm not a big fan of GNFB, and I also know how clean and open something can sound without it - so I'm not surprised that it's controversial 🙂.

It's still got some feedback anyway, the thing is we don't have feedback of the speaker cones or the air, we have feedback from the speaker terminals - so the NHB-108 just pushes that feedback point back behind the followers... 😀
Click to expand...
I got one of these and it’s performing really well. I just think it is a little harsh sounding in the midrange, probably a little scooped around 1Khz. Female vocals and saxophones on some recordings can be fatiguing. Any ideas to remedy this?
I’ve already swapped the caps in the power section with Mundorf MLytic 10.000uF and replaced all connectors with better gold plated copper ones, all with good results.
 
#2,357
I bought the above mentioned amp as well and have listened to it on three different speakers - the result has always been the same: to my ears very pleasing, no harshness at all, open and extended highs, exellent bass (not too "dry"), great holographic sound stage - hence: the best amp I have ever owned (and that includes a variety of highly regarded tube and solid state amps) - but of course YMMV 😉. BTW: build quality is very good.
 
#2,359
I am thinking of replacing output caps with larger value mundorf caps or similar, instead of 12 x 10000uf, aomething like 12 x 15,000uf (or maybe ~12,000)...and add (not replace) silver pure strips to output.speaker terminals, and.same.for connection to rca's and xlr's.
I did the same silver rewiring on my Rotel BX 990 and its a totally different amp...altho it was good before, but not like it is now...so same for the Dartzeel chi-fi clone...

Is higher value output caps a good idea??
 
#2,360
Hi tigerscent

To use bigger caps are principal a good idea but the rectifier could be the weak point. The caps want to load current and they dont care where it come from 😉
The transformers can deliver in this case a lot of current...the rectifier is in between both and that is the weak point.
On the pics i see "normal kpcb xx" rectifier they can handle a lot of current too. You loose about 1.3-1.5 volts on the rails but that is no issue.

Here we have 3 x caps per rail per voltages ( V+....V-) ...so 6 caps per amp channel.

So If 22000 uF or more fit there that should be no problem at all.

Kr Chris
 
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