pioneer a 88x can it be tweeked ??

paul.42 · 22nd November 2011, 08:47 PM

Pioneer A88X Schematic.zip
hi all iwas woundering if anything can be done to this amp,op amps caps etc..

paul.42 · 23rd November 2011, 10:17 AM

going to try the opamps first,will try opamp2604.

homemodder · 23rd November 2011, 11:12 AM

These are pretty nice amps, nonswitching outputs high current output capable and sound pretty good. Considering the age of the amp I would recommend you rather start with replacing the caps especially the ones in the power supply circuitry and the main rectifying caps. After that you could also have a look at the caps in filtering and coupling circuitry depending on what was originally used and if you have access to a scope the compensation ones too. A bit of a warning, be very becareful as to not damage the nonswitching IC, will be very hard to replace.

paul.42 · 24th November 2011, 08:15 AM

Quote:

Originally Posted by homemodder

These are pretty nice amps, nonswitching outputs high current output capable and sound pretty good. Considering the age of the amp I would recommend you rather start with replacing the caps especially the ones in the power supply circuitry and the main rectifying caps. After that you could also have a look at the caps in filtering and coupling circuitry depending on what was originally used and if you have access to a scope the compensation ones too. A bit of a warning, be very becareful as to not damage the nonswitching IC, will be very hard to replace.

could be a plan,would you change like for like or change any of the values of the caps.and would you change caps in the signal path to wimas,ive heard of some people doing this before.

homemodder · 24th November 2011, 10:44 AM

Like for like is a good idea but in the case of the rectifying caps Id probably go a size or two up, that is space permitting on pcb. Pioneer usually used better than standard caps so Id get some good ones for replacement. Since youre in the UK and can easier purchase, have a look at BNC slitfoils, excellent power supply caps.

Wima polyprops are very good yes, but this again is size permitting, these caps are much larger, otherwise go with high quality electros. It also depends on what you want to spend to restore the amp.

paul.42 · 29th November 2011, 06:55 PM

op amps fitted,big difference in sound.

Mooly · 29th November 2011, 07:05 PM

That's good to hear.

Did you go for the OPA2604 ?

paul.42 · 29th November 2011, 09:26 PM

Quote:

Originally Posted by Mooly

That's good to hear.

Did you go for the OPA2604 ?

yes i did,i cant believe how much the sound has changed,its more detailed for sure.very pleased..

23rd November 2011, 10:17 AM	#2
paul.42 diyAudio Member Join Date: Jul 2007	opamps going to try the opamps first,will try opamp2604.

29th November 2011, 07:05 PM	#7
Mooly diyAudio Member Join Date: Sep 2007	That's good to hear. Did you go for the OPA2604 ? __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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23rd November 2011, 11:12 AM	#3
homemodder diyAudio Member Join Date: May 2006	These are pretty nice amps, nonswitching outputs high current output capable and sound pretty good. Considering the age of the amp I would recommend you rather start with replacing the caps especially the ones in the power supply circuitry and the main rectifying caps. After that you could also have a look at the caps in filtering and coupling circuitry depending on what was originally used and if you have access to a scope the compensation ones too. A bit of a warning, be very becareful as to not damage the nonswitching IC, will be very hard to replace.

24th November 2011, 10:44 AM	#5
homemodder diyAudio Member Join Date: May 2006	Like for like is a good idea but in the case of the rectifying caps Id probably go a size or two up, that is space permitting on pcb. Pioneer usually used better than standard caps so Id get some good ones for replacement. Since youre in the UK and can easier purchase, have a look at BNC slitfoils, excellent power supply caps. Wima polyprops are very good yes, but this again is size permitting, these caps are much larger, otherwise go with high quality electros. It also depends on what you want to spend to restore the amp.

29th November 2011, 06:55 PM	#6
paul.42 diyAudio Member Join Date: Jul 2007	op amps fitted,big difference in sound.

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