The $400 is well spent on reissue Gold Lion KT-88s. I was really pleased with the impact it had on my sound. I won't say that they have a warmish darker sound. The Chinese 6550s sound SS liketo me I find much more midrange with the GL reissues and none of the Bang and sizzle I hear with current production 6550s. Just MHO, feel free too argue.
If you really want to warm up the sound then rolling the input tubes will likely do the trick. Unfortunately you are going to have to be a good shopper and find some original Mullards preferrably 50-60s Blackburn 12AX7s. You can get them as used for a lower price and most will last a very long time. The same advice for the 12AT7s get real old Mullards.
They won't cost you $400/pair if you shop around if you buy absolutely perfect NOS tubes from certain dealers they will but you don't have to go that route. Check out Brente Jesse at audiotubes.com or Upscale Audio or some of our Audiogon regulars like Jim Sautter and see what they have in your price range. In any case the GL KT-88s are a must. |
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. |
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. |
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. |
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. |
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 |
Mark,
Having a Jolida 502A myself and have replaced caps and resitors, ect which I felt definely improved the sound of the amp. Nevertheless I think replacing the your pre-amp tubes(12AX7s and 12AT7s)will probably net you a better sounding amp (Jolida tubes ARE NOT the best sounding tubes you can have). I myself use NOS RCA in the 12AT7 postions and current issue Tung-sol in the 12AX7 postions. Switching out tubes definely change the sound of this amp, and it's one of the "fun things" about having tube equipment and it really doesn't have to be all that expensive. Truth be told, I have an assortment of current and NOS issue pre-amp tubes and I doubt I have much more than $100 invested in them. |
Mark,
One more thing, I'm in agreement with Newbee conserning the Tung Sol 6550 reissues. You can get a quad of them in the $200 range. |
Thanks for the great info. I'm moving tomorrow so I will have to put this on hold for a couple weeksmuntil settled. Then let the tube fun begin!!!
I really find all the input very helpful but I am like a kid on his best Christmas morning and waiting will be hard. I'm sure over the next week I'll buy many different tubes.
Thanks again and I'll be back
M |
I know this is an old thread. I'll keep my fingers crossed. I'm interested in upgrades to the jolida 502a. Just dug one up at my brother's house and it works.
Johnsonwu i like what you said. Reminds me of k&k audio's dynaco st70 upgrade . I'm definitely interested in any more information that you may have. Would like to run in triode, better caps, resistors, etc. Wouldn't mind bypassing the entire preamp & just convert to dedicated amp, which I read somewhere could be done.
Thank you guys
|
Get in touch with the folks at Jolida in Maryland (phone or email; Michael Allen does reply to email). Years ago I had a 502B that I sent in to them for mods. The cost was very reasonable and the turn around quick. Their work definitely resulted in improved sound. Can't hurt to ask whether they would do the upgrades you want. Good luck. |
+1 Ghosthouse. Contact Jolida, as they will advise on upgrades. |
