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I recently bought a Jolida CD100a, which I am not crazy about. Even after rolling the stock Sovtek 12ax7LP tubes with EH, and NOS Sylvanias, I am getting a harsh glaring lower treble sound, with MIA upper treble, compared to my el cheapo NAD 542, which by comparison is smooth, quiet, sparkling and extended. I was reading in Joe's Tube Lore where he loves substiututing the 5751 tube for the 12ax7(which he says all stink sonically). I woulr like to try that, but since the 5751 has 30% lower gain, am I going to get 1.4 volts output instead of 2? Also, will this lower gain change the circuit or cause any problems with the unit? Another option is to upgrade, would better diodes, caps, resistors, jacks help? thanks for any insight.
Follow Ups:
You may find that you like the slightly lower gain of the 5751. You can use any tube in that family but you will get varying results based on the gain of the tubes among other factors.
-Bill
I agree with the other posts here that a better power cord does indeed help the sound of this player. I have tried GE 5751's and while they were not bad I found them to be a bit recessed in my system. I have had great luck with both Tungsram and Sylvania 12ax7's. Good luck and hope you find a match that works for you. I really think this player can be a great choice in the right system.
I just recently switched the factory Jolida tubes with a pair of black plate GE 5751's and then switched agin for a pair of Sylvania 5751's. The GE's seem to take about twenty five hours to open up, where as the Sylvanias seemed to be there in about ten hours. The funny thing about the OEM tubes (marked Jolida)was that in some places they were better than the GE's and almost as good as the Sylvanias. As for the power cord, it does make a difference on this unit.
gary
I'll try it.No expert on Jolida, but I have owned it and rolled 5751s. Yes, definite improvement is what I recall, but pls don't ask specifics as it was a while ago and my audio experience then was less than it is now (not that it's anything to show off about now!)
I also don't recall a significant or even obvious drop in output level, specs nothwithstanding. Rolling tubes is not so expensive and easily reversible. This is perhaps not so true for the other things you mentioned, so it'd be worth your while calling up a reputable tube shop and scoring a pair of 5751s. If you don't like what they do, you can put them on Agon and recover 70% or so. Or go to Agon directly, but verify the source - it seems there are plenty of fakes around.
I have a JD100a and have swapped in EH 12AX7 and GE 5 Star 5751 tubes.
The 5751 tubes are better than the EH but not by an enormous amount. They are smoother, more extended and have a bit more mid range bloom. But, again, I would not say the change will leave your "jaw dropping".As for the shrill, edgy treble, I eliminated most of this with a good set of ICs , a power cord swap and plugging it into a PS Audio UPC200.
I have had the JD100a playing these past few weeks to burn in a new preamp. I had to move it out of it's usual rack spot and this meant leaving the UPC200 and the upgraded PC behind. I also left the good ICs behind and just used a pair of Monster Cable ICs between the CDP and the pre.
Well, the harshness was there in spades. The stock PC directly into the wall with the cheap ICs just ruined the sound. I wasn't surprised but I was impressed by just how bad it was.
So I swapped out the cheap ICs for VH Audio Pulsar AG and there was an immediate improvement. Then I swapped out the stock PC for a Flavor 1 and that brought it back to almost right. I haven't plugged it into the UPC200 again ( it's too far away in the regular rack).
The best IC i've found to use with my Jolida is a ZU Gede. The worst was a Monster.
gary
Actually I use a PS audio power cord. at 10 Guage is it so ridiculously heavy that gravity slowly pulls out the iec connector. I use AQ viper IC's
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