Hello everyone, I need some help.

I have the oppurtunity to buy either a Pioneer C-90 preamp or a Pioneer C-90a preamp. Since I haven't seen (or heard) a C-90a I would like to know in what aspects it differs from the C-90.

I recall hearing that the C-90a is pure audio without the video-switching, is this true?

I sold the C-90 when new and have owned various C-90 and C-91s. I, also, have never heard of a C-90a. My best guess would be the C-90a (if it exists) would be a multi-voltage model where the C-90 was not. IMHO there was too much in the way of video switching on the C-90 to just eliminate it. They almost certainly would have changed the chassis/case (too many now useless buttons, etc.) and given it a different model number. Again, just a guess...

The C-90a an improved c-90... the video inputs was removed to make space for internal DAC with 3 digital inputs, this DAC is proberly the same technology like the one used for the A-90D...a few mods was made in the analog circuits ...better caps, resistor values adjust :scratch2:
Now when we at it ...The M-90a was an enhanced model of the M-90 to gain better sonic quality....afir. it was done by use of better caps, a few resistor values adjusted. :naughty:

The C-90a an improved c-90... the video inputs was removed to make space for internal DAC with 3 digital inputs, this DAC is proberly the same technology like the one used for the A-90D...a few mods was made in the analog circuits ...better caps, resistor values adjust :scratch2:
Now when we at it ...The M-90a was an enhanced model of the M-90 to gain better sonic quality....afir. it was done by use of better caps, a few resistor values adjusted. :naughty:

PMik, thanks for sharing the info with us. First time I've heard of a C-90a. How does it compare to the C-91/M-91 combo?

thanks :)

bsam8

Both of them is very nice products.
C-91 delievers better performance in technical and sonic quality compared to the c-90, but we are dealing with small differences :thmbsp:
"Dark horse" is the C-90a and is the one i personal want of these pre-amp ...its more simple and straight forward in the layout and the DAC makes it a perfect match for my PC :naughty:

The bad part (worst case) of these pre-amps. :thumbsdn:
Use of what i reconize as problematic relays ...ten pieces for C-90 which should be changed img. to new ones ....by age the contacts can easy generate/add 0.1-2% THD on the output.
depended on the source and functions activated....the problem can be more or less audible ;)

Im not quite sure about the power-amps... but :scratch2:
i have seen some clear problems with M-90 :worried:
bad soldering, thin boards which twist and turn over time, hot! local PSU's and other relaiblity related issues ...i will still get these amps if the price is in my favor ;)
I believe there is minor differences betwin the M-90(a) and the M-91.
and the later is just the flawless finalized product in the series. :yes:

bsam8

Both of them is very nice products.
C-91 delievers better performance in technical and sonic quality compared to the c-90, but we are dealing with small differences :thmbsp:
"Dark horse" is the C-90a and is the one i personal want of these pre-amp ...its more simple and straight forward in the layout and the DAC makes it a perfect match for my PC :naughty:

The bad part (worst case) of these pre-amps. :thumbsdn:
Use of what i reconize as problematic relays ...ten pieces for M-90 which should be changed img. to new ones ....by age the contacts can easy generate/add 0.1-2% THD on the output.
depended on the source and functions activated....the problem can be more or less audible ;)

Im not quite sure about the power-amps... but :scratch2:
i have seen some clear problems with M-90 :worried:
bad soldering, thin boards which twist and turn over time, hot! local PSU's and other relaiblity related issues ...i will still get these amps if the price is in my favor ;)
I believe there is minor differences betwin the M-90(a) and the M-91.
and the later is just the flawless finalized product in the series. :yes:

PMik, again thanks for the info, nice to know and it's been a pleasure owning these babies (C-91/M-91) :thmbsp:

regards,
Ben

Today I bought a C-90 on Ebay:

http://i20.ebayimg.com/03/i/03/ff/7c/2f_1_b.JPG

When it arrives I can tell you more. I have one Sales brochure from 1993/1994 , including C90a C73 ....

Congrats! :)

Siamac ....Are you able to scan or make detailed pictures of these brochures, would love to see them :yes:

Ps. got the schematics for the C-90 ...we could make a sort of trade :naughty:

http://www.siamac.de/backup/C90a.jpg

http://www.siamac.de/backup/C-9090.JPG

Now, I have got a Pioneer C-90 in my home. Mine is, as the one in the pictures above, without the video switching.

I have had some problems with the two relays on the output stage but otherwise it wors just fine. Does anyone know of an equivalent relay to the ones that were in the C-90. I haven't been able to find any and since the original ones will start to act up eventually it would be nice to find some replacements.

Could someone share schematics of C-90? I've just bought it and seems it needs some fresh parts and tweaks.

Thanks in advance.

wirbud () go2 pl