>Decided to power the emitter of the first transistor from an unstable power source? You won't get dirt out of the power bus ?
I thought about it -
It can be powered from +15V, I tried it, but sim results are slightly better if it's powered from the rail.. I think sim can be perfected even if it's powered from +15V, but I had no patience...
Even in your version it was powered the same way...
What do you think about R5/R14 and change in R1?
I thought about it -
It can be powered from +15V, I tried it, but sim results are slightly better if it's powered from the rail.. I think sim can be perfected even if it's powered from +15V, but I had no patience...
Even in your version it was powered the same way...
What do you think about R5/R14 and change in R1?
Posts of mine about the Hartsuiker's circuit :
https://www.diyaudio.com/forums/sol...lls-power-amplifier-book-201.html#post6061860
https://www.diyaudio.com/forums/pass-labs/262821-class-ap-amplification.html#post4080735
75/150 Ohm resistors don't need to be bigger than 250mW.
On the other hand - Zener resistors need to be preferably 1W. They run hot.
Zobel resistor need to be 1W.
Basically all the resistors but Zobel and Zener, and 20k resistor - can be 250mW.
I see you are planning to only run one pair of output devices - in this case
I'm not sure you need source resistors for the fets.
See this thread: Emitter resistor in HexFet OPS
especially Ian Hegglun's opinions. These resistors are increasing Thd.
1. https://www.diyaudio.com/forums/solid-state/349593-emitter-resistor-hexfet-ops-2.html#post6083300
2. Emitter resistor in HexFet OPS
3. Emitter resistor in HexFet OPS
Also - for the op-amp - in the sim LT1056 is used, because TL071 is not in standard spice lib.
LT1056 is much faster, and might be causing oscillations - just a warning. TL071 is very stable and works just fine.
No difference in the measurements/listening. And it's cheaper too.
In this amp (actual build), I did try LT1056, and it was working fine, but in several other amps
with op-amps (actual builds), it did oscillate, even though it shouldn't
Electrolytic capacitors from Zeners, should go to dirty ground. And Zeners of course too.
Only input network, and feeback cap (220uF) should go to signal gnd.
Sorry for chaotic remarks, but I'm just looking at the pcb, and updating this post
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Thank you. Yes, I know, but I have tons of 1W Dale resistor (from previous projects). For Zobel I have Panasonic 2W's, rechecking its size is needed.
@minek You wrote this earlier:
"Q2/Q3 (VAS transistors) initially were 2SA1381/2SC3503. That didn't work out in real build. Voltages at bases of drivers were all shifted couple of volts down.
Tried to replace them with MJE340/MJE350, and everything worked as in the sim.
My MJEs have similar (or perhaps slightly lower betas than 2SA/SC transistors).
So overall, I don't really know why MJEs work fine, and 2SA/SC don't.
In the sim they all worked fine.."
So you still recommend MJEs in VAS?
"Q2/Q3 (VAS transistors) initially were 2SA1381/2SC3503. That didn't work out in real build. Voltages at bases of drivers were all shifted couple of volts down.
Tried to replace them with MJE340/MJE350, and everything worked as in the sim.
My MJEs have similar (or perhaps slightly lower betas than 2SA/SC transistors).
So overall, I don't really know why MJEs work fine, and 2SA/SC don't.
In the sim they all worked fine.."
So you still recommend MJEs in VAS?
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>So you still recommend MJEs is VAS?
Tricky question
Generally NO,
BUT
In LMK amp I tried 2SA/2SC devices and I couldn't make it work.
At the same time, I was fiddling with Vbe spreader transistor, so I'm not sure who's fault was it - VAS devices or Vbe multiplier device...
The fact is that amp finally worked fine with MJEs.
I didn't retry other devices again; and also I have too many MJEs left, and I have to use them up, so I left them in place.
Similar (Russian) amps were built with 2SA/2SC devices, so I'm sure they are workable, and they definitely should be better than MJEs.
We can see it in the sim.
It's your call. Both of my builds were with MJEs, and I'm happy with them.
Tricky question
Generally NO,
BUT
In LMK amp I tried 2SA/2SC devices and I couldn't make it work.
At the same time, I was fiddling with Vbe spreader transistor, so I'm not sure who's fault was it - VAS devices or Vbe multiplier device...
The fact is that amp finally worked fine with MJEs.
I didn't retry other devices again; and also I have too many MJEs left, and I have to use them up, so I left them in place.
Similar (Russian) amps were built with 2SA/2SC devices, so I'm sure they are workable, and they definitely should be better than MJEs.
We can see it in the sim.
It's your call. Both of my builds were with MJEs, and I'm happy with them.
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With LTP input slew rate is 50V/us. УНЧ-ВВС-2011 has 100V/us.
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