Preamplifier, worth modifying? Pics attached

gil1

Member
2009-01-01 11:52 am
Just got a Pyle PYP-X1 preamp for next to nothing, solid build, looks good but the sound could be a lot better.

Dont really want to spend a lot of cash squeezing juice out of a rock but what do you think guys, is it worth changing a few caps, upping the power supply caps, etc? Im open for suggestions other than using it as a door stop.

Gil
 

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Yes I agree with Tekko. OPA2134's are good and cheap, and are pin compatible with your 4558's. I have done this in many amps and CD-players and the sound improvement is enormous!
It should work fine without extra components, but if you want to be super-safe, you could add a small cap of 100pF between pin 1 and 2, another 100pF between pin 6 and 7, and a film-cap (MKT, MKP or similar) of 10nF between pin 4 and 8 (power supply pins), on each of the OPA2134.

Another modification that improves sound quality quite a bunch is to parallel all those electrolytic capcacitors with film-caps of 10% of the value (100nF - 1uF). This goes for both those that are in the power supply and those that carries the actual audio-signal. The easiest is to solder these caps to the pins of the original caps on the underside of the board.

Have fun, and on't forget to reply with images and your listening impresions :D
 

gil1

Member
2009-01-01 11:52 am
Yes I agree with Tekko. OPA2134's are good and cheap, and are pin compatible with your 4558's. I have done this in many amps and CD-players and the sound improvement is enormous!
It should work fine without extra components, but if you want to be super-safe, you could add a small cap of 100pF between pin 1 and 2, another 100pF between pin 6 and 7, and a film-cap (MKT, MKP or similar) of 10nF between pin 4 and 8 (power supply pins), on each of the OPA2134.

Another modification that improves sound quality quite a bunch is to parallel all those electrolytic capcacitors with film-caps of 10% of the value (100nF - 1uF). This goes for both those that are in the power supply and those that carries the actual audio-signal. The easiest is to solder these caps to the pins of the original caps on the underside of the board.

Have fun, and on't forget to reply with images and your listening impresions :D

So by-pass the electrolytics rather than changing them?

BTW thanks to all for the input
 
OPA2134 wont be worth it as these are much faster opamps - they will probably just oscillate. Unless you're planning to go further eg rebuild the power supply etc, there is no point. Stick to the NE5532. Yeah they are "old" opamps now but they are still very good quality especially for the price.
 

gil1

Member
2009-01-01 11:52 am
Changed the opamps to OPA2134 and right away the sound became "softer" and more detailed, this preamp in its original version had a very hard fatiguing sound, it is still in your face kind of sound but its tolerable now and not fatiguing to listen after a while. Also beefed up the power supply caps, Im wondering if changing diodes with schottky's would help any?
 
..... hm...lets see .... adding supreme op amps in a machine that has no tone control bypass switch doesnt acually make real sense

i presume that the benefit of a good op amp will be consumed by the limitations of the tone control

then again upgrading a machine that has such a terible inputy selection and presumambly terible crosstalk figures either from left to right or if more than one active source is conected to it is absolutelly pointless to my understanding ...

either you simply replace the chips and keep it as absolutelly is and may add a few better caps in the power supply where the diference will be bearly audible

or remove the guts from it since its quiet roomy install inside a decent line stage skip the tone control and use a shunt topology relay stack for input selector...this will end up to good hiend machine ...

edit : forgot also the pot hat needs to be replaced

this is how i see it
Regards sakis