As I have a Jolida 302b (driving Meadowlark Kestral 2s), I can't comment on 6550 power tubes. However, I think you can get an equally big, if not bigger, bang for your buck by upgrading the small tubes. I've tried Sylvania, GE and Raytheon triple mica blackplate 5751s in place of the stock 12ax7s and have been extremely happy with the results -- essentially, much more bloom. I also replaced the 12at7s, first with Mullard 6201s and later with Telefunken ECC801Ss, and am really happy with how the bass tightened up over the stock tubes. Jolida and Meadowlark: a great combination.
That's interesting, I hadn't yet considered that. I was driving Kestrel 2's myself(for sale on 'Gon) but was offered a good buy on a great pair of Osprey's.
Well, I have the older 502A. It's heavily modified (see my bedroom system thru the "System" link).
I still use the stock "winged-C" 6550 tubes & like the overall sound.
The 12AX7 is a Mullard NOS & the 12AT7 is a RCA NOS.
I'm very happy w/ the sound. I like a neutral sound & I think that I'm closer to that type of sound vs. the un-modified unit.
I should mention current tubes are: Electro Harmonix 6550 EH, Electro Harmonix 12AT7EH and Jolida 12AX7A.
well, I do own the wrong Jolida amp as well to give you recommendations for powertubes, but here is a selection of tubes I run in my JD302b:
Jolida (Chinese) 12AX7
EH 12AX7 gold pin
EI Elite 12AX7 gold pin
1970s Tesla E83CC Frame Grid gold pin
1980s Jan GE 5751
EI Elite 12AT7 gold pin
1980s Mullard CV4024
19??s BRIMAR 6060 T-Series Black Plates
I have not had a chance to listen to all of them very seriously, but so far my favorite is the SED, Tesla, Brimar combination for a little more forward, very lively engaging sound. SED, Tesla, Mullard is slightly more polite and laid back but preferrable if you like a smoother sound.
Probably more important is the question: What sound are you looking for?
Thanks, lively and engaging is my preference. I listen to a lot of blues and like the vocals right in front of me.
Have you tried talking to Brendan Biever at Tube World? He has Jolida amps and is pretty knowledgable about NOS tubes for them. I don't own a Jolida, but when I dealt with him he helped me out with my Cary and in the course of normal conversation we got to talking about his gear and the tubes he uses. FWIW.
Thanks, I'll try that.
I was using a 502A until recently. For power tubes, I had great luck with the JJ Tesla KT-88s. Nice fat, warm sound. For the 12AX7s, the NOS Telefunken smooth plates are awesome - but expensive. For my 12AT7s, I used NOS Sylvania with gold feet - not that pricey, but great. Personally, I would go with new tubes for the power tubes and NOS for the preamp tubes - best of both worlds - great sonics and reliability.
Are KT 88's and 6550 interchangeable? I'm new to the tube scene. I ordered Electro Harmonix tubes to replace the Jolida labeled tubes in the pre amp which I'm sure are chinese in origin. That would give me all Electro Harmonix tubes at this point. Any suggestions?
" Are KT 88's and 6550 interchangeable? I'm new to the tube scene."
Yes. There are some nos 6550's such as GE and Philips 6550's that are reasonalby priced and are wroth a try,
Thanks Larry. I saw at the tube store where the current electro harmonix power tubes are highly recommended. Maybe they aren't so bad after all.
Beernut I thought you had a 302B. Perhaps I am mistaken.
I have the 502B.