Audio Discussion > DIY

Jolida JD9 op amps and gain experiments

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Jim Pittsburgh:
Just thought I'd share:  ordered four OPA 627s and two OPA637s thru eBay / China supplier, after reading such rave reviews about this "upgrade" to the JD9 phono pre-amp on more than one of the boards..... Don't get me wrong,  I'm basically very happy with the sound of the Jolida with the current tubes I'm using, but figured "what the heck" after having had such good results with the op amp replacements in the dbx cd player.....  Needless to say, this time things didn't go nearly as well lol 

Although they were clearly marked as 627s and 637s I'm not at all sure what I actually received. But the resulting change in sound was just terrible.... I tried every possible combination of the existing six matching op amps and the three pair of new ones... with not the slightest improvement in sound.....actually all I got for the effort was varying degrees of muddiness, over emphasis of portions of the audio spectrum and even a bit of distortion.... back to the originals.

Also, a big thing on a number of the boards was to use the high outputs without any gain switch turned on for MM cartridges, and some saying it's the best settings for everything (bypasses a circuit) ... with my ClearAudio MM cartridge the result was that it sounded like the phono pre amp was over driving the inputs at anything beyond background levels....  I even played with a number of other settings on the Jolida and within the receiver to try and make the most of the change...... but again ended up right back where I began....

I know it's a function of different ears, different equipment and maybe for part of these experiments, bogus op amps, but the internet / boards and the sheer number of insistent "best thing since sliced bread" posts,  never ceases to amaze me... lol   

Anders:
I wouldn't trust parts from China.

AdamG:
I guess that's part of the thrill of the chase! At least you were able to tell a difference, for better or in this case for worse. Now you know 1 more thing not to try!

Sir Thrift-a-Lot:
I'm not sold on op amp rolling anyway.   Some of the specs specific to one amp can be very different on another.   I don't know about just throwing anything in.

Jim Pittsburgh:
Adam and STAL.... agreed/ understood.... but I found it funny, and frustrating, particularly after all the reading I did.... Most likely it's bogus op amps.... or all those posters on Audiogon, Audiokarma, DIYaudio etc etc have seriously bad hearing .... lol

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