fixed!
Hi!
the amp is repaired, and then modified.
the cost are burned:
After regulation the bias I started to listen to the music and it was very disappointing, the sound was rough and boomy with killer load Magnepans MG1.5/QR (3.5 Ohm).
I thought that if the amp fails, I will never repair it, but rebuild to VSSA, or something.
I switched on Marcus Miller The Sun Don't Lie, pumped up to 32W on the power indicator and went out the house. It was not so loud regarding that Maggies were only 86dB/1W.
After 2 hours the sound lost roughness and boom.
After a few days the sound is soft, clear and detailed, no way of "listening fatigue".
I can recommend the changes I made to every A-Xx amp user.
Later I will try to send important pics from the surgery.
Hi!
the amp is repaired, and then modified.
the cost are burned:
- 1pc 2SD845/2SB755
- 2 pcs 2SC2235/2SA960
- 2pcs VC5022
- 2pcs 2SA1943/SA5200
- 2pcs BD139-16/140-16
- 2pcs 270 Ohm 0.125W
- 4 pcs 10 Ohm 0.125W
- bias pots to new 500 Ohm multiturn
- main electrolytics for 10mF/63V Nichicon KG Gold Tune
- second electrolytics for 100uF/100V Nichicon KZ
- input and feedback electrolytics for bipolar Muse 47uF/50V and 100uF/50V
- std ceramic caps for polystyrenes and NP0/C0G 1812 ceramics
After regulation the bias I started to listen to the music and it was very disappointing, the sound was rough and boomy with killer load Magnepans MG1.5/QR (3.5 Ohm).
I thought that if the amp fails, I will never repair it, but rebuild to VSSA, or something.
I switched on Marcus Miller The Sun Don't Lie, pumped up to 32W on the power indicator and went out the house. It was not so loud regarding that Maggies were only 86dB/1W.
After 2 hours the sound lost roughness and boom.
After a few days the sound is soft, clear and detailed, no way of "listening fatigue".
I can recommend the changes I made to every A-Xx amp user.
Later I will try to send important pics from the surgery.
Nonswitching circuit
Hi!
For last few days the amp was working with higher than recommended in SM bias current (90vs45mA) but I am thinking to lower it according to SM.
Not because of the heat but designer's intention.
In meantime I checked the way of working of Super-A circuit in simulation and it looked like it worked a bit from hard clipping, not soft big radius rounds, only sharp corners were rounded up.
What do you think, is such behaving acceptable for nonswitching circuit?
Hi!
For last few days the amp was working with higher than recommended in SM bias current (90vs45mA) but I am thinking to lower it according to SM.
Not because of the heat but designer's intention.
In meantime I checked the way of working of Super-A circuit in simulation and it looked like it worked a bit from hard clipping, not soft big radius rounds, only sharp corners were rounded up.
What do you think, is such behaving acceptable for nonswitching circuit?
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