| MTO audio |
NEED HELP for Pioneer A400x mods
Hi every one, I am new to this forum, I am working on a A400x at the moment.
For the dc coupling I used WAMA 3.3uF MKS4 non-polar. On power supply, i used a high speed rectifier bridge and 0.1uF WAMA bypass on every filter caps. I also added few 100uF/50V Panasonic FC and WAMA MKF on V+/V- of each transistor.
After the mods, rectifier replacement improved the quality of the bass a bit, WAMA give very nice high end, however the whole image became too bright.
Is there anyone have experienced on mods A 400 or A 400x?
Q1: how can I avoid the sound become too bright?
Q2: how can I get better bass control?
Q3: if I increase the bias current, does the 2SA/2SK driving pair needs a heat sink?
Q5: A400 originally 20mA on each power transistors, I am going to boost up to 100mA. Would that give me a warmer sound and better bass control?
Thanks very much!!!!!!!!!!!!!!!!!! |
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| rabbitz |
Did a few small mods on my A400X.
Input caps changed to 4.7uF Nichicon ES and maybe Black Gate N or NX would work well here.
The main power supply caps were changed to 10000uF Nichicon Gold Tune.
Caps for op amp were changed to 100uF Nichicon Fine Gold. Tried a few different op amps such as OPA2134, 5532, AD826 but the original M5220 sounded the best. The other op amps may have needed some different power and by-pass caps but wasn't worth playing with.
The mods have seemed to give a bit more drive all round and more control in the bottom.... deeper may be?? ... a tad more clarity but no other noticeable changes. For the few dollars, was worth it. |
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| zanash |
I suspect your dc decoupling caps are the issue ....try doubling them up to get 6-10uf ...or try a different cap..
I don't have the schems so can't offer any more advice. |
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