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Jolida sj502a tube advice

Hello
I just bought a Jolida sj502a tube amp and was wondering what tubes would you recommend and what will they do to the sound of the amp.

Currently has Sovtek 6550we x 4, Jolida 12ax7a x 2 and some 12at7 tube with no writing except the model numbe on the side of the tube.

I like a liquid, warmer laid back sound with really good detail and a solid bottom end. I find some of the tubes are to "detailed" and the mids/upper end is right in my face and that doesn't work for me.

Any suggestions would be helpful. This is my 2nd all tube amp but I am still a newb at the tubes. I will tube roll at some point to try it and see the difference. The one thing I love about this amp is it is very quite and really does sound awsome. I'm just looking to warm her up a bit more.
This is how I'm running it
Jolida JD50a control center into the 502 into Energy Veritas 2.3's through Harmonic Tech Pro-9 speaker cables.
I have an Oppo BD-83SE with the upgraded analog section and Sabre DAC's. I am currently trying different IC's as I have a few different ones and I build custom IC's so I am trying those as well. You definateley get instant feedback when I cahenge my IC's which is what I want anyways.

Thanks again but no $400 tubes except maybe to replace the 4 6550s.

Mark
128x128eagleputt
newbee
4,767 posts
 
I used the Sovtek's in several different amps. Nice mid-range and highs. Not at all bright BUT the bass is really lacking I think. I have not used a Jolida so this is just a generic reference.

I used SED 6550's which were much better in the bass but they very linear and only in the very top end were they rolled a tad. In the wrong amp or with the wrong ancillary tubes they could sound cold/bright.

I'm now using Tung Sol reissues. Full bass, clear 'tuneful' mid range, and softly rolled highs. A nice tube if that is the sound you are looking for. Obviously, as mentioned (sort of) the sound is going to be contingent to some extent on the small tubes.
johnsonwu
469 posts
 
Tube rolling on this unit is a waste of money until you have addressed the obvious flaws:

1. Ultralinear (unless you really need the power run it in triode mode)
2. Coupling caps (get PIOs or Teflons for the 4 coupling caps)
3. high voltage bypass @ the input and driver stage
(use film caps instead of the stock eletrolytics)
4. main filter caps (change to 560uF 400V)

This will be a much better $400 spent than on any NOS or reissue tubes.
mechans
3,048 posts
 
Johnsonwu,
I respect your opinion without knowing how the 502 sounds with these mods. I expect they really will make an important difference.
However most of us are not equipped to do the mods ourselves or have access to electronic technicians who we know who will perform mods they don't use themselves or don't suggest recommend themselves. Controlling costs and assured quality by after market modification represents a challenge to the non DIYer.
Rolling tubes however is accessible and does have a meaningful impact on ultralinear amps, I am sure of this. The input tubes which are not in PP and almost allways have a meaningful impact on the sound. Indeed among many many rolling experiences, In every instance I was able to taylor the sound, except once. (An ARC preamp, which warned that tubes in certain positions, did not impact the sound. They were correct.) Again It is the only instance I have ever encountered in my years of tube rolling.
johnsonwu
469 posts
 
The layout of the Jolida 502 is, unlike Audio Research amps,
so simple that an old-school TV repairman can easily mod with one sheet of instructions.
No need for mega expensive mod shops, just a shopping list of components from ebay and mouser.com and 2-3 hours of the solder tech's time.
I have tried tube rolling an SJ302 without mods,
the results were minimal.
Email me if you have a 302 or 502 and want the list of mods and where to place them.
eagleputt's avatar
eagleputt OP
2 posts
 
Thanks guys for all the suggestions. I Plan on having the caps etc... Changed out. I know that will help and is probably a good place to start because I don't want to buy tubes and then need other tubes after the innards are changed. It already has som work done to it as I have to hook/run all the other cOmponents through the JD50a control unit.
I'll contact the seller and see exactly what has been done.
Thanks again for all the input.
Mark
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