DIY Class A/B Amp The "Wolverine" build thread

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#2,022
I chose solid state for a reason. My lowliest ss amp outperforms my best tube amp on Magnepans except but for a few areas. I consider a tube, or vacuum-state device to be a homogenator. It gives a junction for the music to come together, to congeal, and is most noticeable in the most intricate and intimate passages in recorded music. Call me crazy but there are a few on this forum that will agree with me. In terms of performance though slogging through silicon wins hands down. I have neither the time nor the patience to deal with multiple systems-hell, I can only listen to one at a time. I just thought the added flexibility might come in handy.
 
#2,028
Toolermike said:
selectable input impedance.
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If you look at the bom and the schematic and observe the changes that would need to happen I'm sure that you'll see that its not practical to attempt this. Some of those nodes are highly sensitive.
If you'd like to do this I suggest that you build a separate IPS board. I have some spare 1st GB ips boards that I could send you at no charge. Just pay the shipping and their yours.
 
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#2,030
Toolermike, I had the same dilemma and finally choose the 22k option. I wanted to leave the possibility open to play around with different preamps, tube amps included, and I figured that for speakers with 86dB sensitivity the extra noise will not be an issue. I can give a feedback on the noise later when I finish the amplifier. Also, if noise becomes an issue I can always change it to 10k by replacing a few components on the input board.
 
#2,031
LKA said:
Did you measure a completed amp in the enclosure or just the module on the bench ?
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The EF3-4 that I measured was on the bench, but being a DIY project measuring in Chassis would not be valid to the performance of the Wolverine itself as everyone's builds, wiring and layout will all be different. I have measured an EF3-3 both in Chassis and on the bench and there was no difference in the results, but as I said everyone's build will differ.
 
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#2,034
To be honest, I would not suggest you to do such a thing. Some posts ago, Andy fireanimal told me he took his excellent measurements on the Wolverine using a 1st group buy board (but don't spread the word, he said me it was a "little secret"...😉).

Gaetano.
 
#2,037
ghitus said:
To be honest, I would not suggest you to do such a thing. Some posts ago, Andy fireanimal told me he took his excellent measurements on the Wolverine using a 1st group buy board (but don't spread the word, he said me it was a "little secret"...😉).

Gaetano.
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They were 1st group buy boards but they had the changes and 10k input modifications that are applicable to the 2nd group buy boards.
 
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#2,038
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#2,039
One technical question: what are the rules when choosing NFB resistors for a given gain. Here these are 27k and 1k and gain is 28. I have active systems and would like all my amps have the same gain so I could switch them. So what about 13k and 470 ohm or 27k and 820 ohm or 13k and 390 ohm. Apartt from thermal noise what is the difference in running this amp (or any amp) with these different nfb resistor values? What are the rules?
Thanks,
 
#2,040
The calculation is voltage gain or ratio, then you need to convert to dB.

27000/1000 = 27

dB=20*LOG10(V)

27=28.627dB

Now I would not just change feedback resistors, there are more components that form the feedback network then just the resistors.
 
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