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26 Jul 2014

Summer games on Onkyo DX-7333 ......op-amp swapping to achieve the best result with an unexpected one!

Oh here we are a Onkyo DX-7333

...since my first listening session I didn't like it so much! 
Anyway I think I developed the capacity to understand if there would be potentialities over a dirty sounding device.....and  I bet over this Onkyo since his first notes!
At the beginning it sounded a kind of compressed and harsh, lacking the bottom bass range at all, but I perceived a particular accurance and 3d sound behind all this crap . you are the first guilty of  this messy sound : the jelly bean JRC4565 ....I think i would prefear his brother 4558....the 4565 sounds some way too harsh!

...some mod around he PCB like a "home made" cooler for the voltage regulator......

....just swapped the original output cap for a pair of panasonic FC.....

.....a couple of National's LME49722 biased in class A .....I added even a 201 feedback polyester cap in the LPF to make mid tone more present......this was one of my best result at all in this device....since I did try will find out very soon!

....oh here you are my bunch of op-amp ready for swapping session.......but I own much more of them to play with!
I tried many of them inside this Onkyo:
AD825, 2 x LT1028 ,LT1057, LME49722/23,LT1649, THS4032,THS4052  at the top and followed by OPA2134,OPA1642,LM6172, CA3260 and TL072/62 were among my favourite......
but after all these highly regarded amplifier I played to try a cheap one like the LF412 Bi-Fet input, first listening it was a little shrill but quite enought detailed.......but what could change the class A bias now??!! Worth to try it!!!
WOOOWWW!!!!! In class A this opamp express all its potentiality! Now it's for sure one of the best of the bunch!.......sparkly, very accurate in details and natural sounding, and in class A it looses his harshness at all! Actually you wouldn't stop to listen it! Great sound!!!!

To be true probably it's not the very best result at all but very close to be the best ........compared to some more refined one it's a tad more dry but best deal for the money!
I found few of the mentioned before to be more refined........among them one of my favourite is the LT1057 that is a tad more beefy compared to LF412 class A, anyway it's quite neutral and natural sounding, very open with an outstanding  midrange. Another competitor is LT1469 very close to 1057 but  tad back in midrange...even AD8065 x2 is the same paste but a tad more laid back. Actually is running a couple of very well performing LT1364 it seems to overcomes the 1057, beeing one of the best of the bunch!
....try also TLC272 , would be a great surprise to your ears!!!!!;)
The moral is that playing is the best way to discovery things!!

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