What 12ax7 and 12at7s are you presently using and which ones have you already tried? Also have you tried any KT88s in place of the 6550s?
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Not sure about the power supply but the caps were Maryland Jolida upgraded (along with other items in the "upgrade" mod version). The 12AT7s currently are EH Russians (the only non-Tung Sols).
The amp is new-ish (newest version actually, and supposedly improved over older versions), I haven't tried any other tubes in it yet, but so far it sounds great (quiet, looks cool, very well built, sweet tone). I'm not complaining, just fishing for info among my fellow tubists. Tubers? Tuboids? Bottle Heads? Valvers? At the current price for these new, I'm surprised everybody doesn't own one just to play with the damn thing. It's fun. I appreciate the suggestions...keep 'em coming.
I went as far as completely rebuilding one.
Only the trannies are left original.
Not sure if Jolida Maryland simply changed Kung Pao caps to Mushu caps.
But mine went as far as V-caps and Mundorf SGO.
Hexfred Diodes, Low ESR Panasonic or Nichicon Filter caps,
replacing gain and driver stage filter caps to Solen or VALAB, triode mode, and reconfiguring gain stage all contribute to a much more musical and open sound.
Much more effective then burning money on tubes (MANY so called Telefunken and Siemens tubes out there are fake)
Tung Sols... this brand is long gone. All you are getting is New Sensor Reflecktor Sovteks.
I have the Black Sable EL 34 and the Shuguang Treasure Series 6CA7, which I am currently using. The Black Sables brighten; the Shuggies dampen slightly. For punk, industrial etc. the Black Sables have more headroom. For Blues, Classical, everything else, the Shuggies are Fab.
Used with ASL AQ 1003DT & de Capo's.
I just bought a Jolida jd-502p My self about two months ago and hell yes tube rolling is fun.the first tubes I changed were the tong sol 6550's to the new production gold lion kt88's. They are not only brighter but have a better extension top to bottom and every thing is more separated with a more defined sound stage. then I moved on to the 12ax7 slot I tried some RCA JRC- 5751WA good top end but no bass at all ended up with some JJ ECC83S gold pins good overall top to bottom but lack a little sparkle in the top end so still looking I have some EI elite gold pins on order. as for the the 12at7's I ended up with some nos mullards cv4024 they are good and quite nice top to bottom and maintain nice sound stage and separation
Hi Wolf I don't have a Jolida but I do have an Octave V70Se which uses a single 12ax7 for an input and a pair of 12at7's for drivers. It came stock with a Sovtek 12ax7 and Rca 12at7wa's. For my taste the Sovtek was too bright. I also have the Russian TS 12ax7 re-issue which also is a tad bright. I needed to calm that down a bit and I like the Rca 5751's. I just received some Brimar Cv4024's and haven't tried them yet.
As far as sizzle my favorite combo so far is very expensive but unreal. Eat KT88 diamonds Gec A2900/CV6091's with the Rca 5751. With that combo the highs just sparkle. That being said I have had just horrible luck with the Eat's. Out of a quad and pair I only have 3 that are stable. I did buy them used so and they are the early versions with just the top getter and read that they were pretty unreliable. I just had to hear them and they are that good (when they work). But I did get 250 hrs of pure enjoyment. I have some vintage Gec KT88's and vintage KR Audio branded Tesla's ordered because they are supposed to be very Eat like sounding. Also as far as the Gec a2900/Cv6091 they are a high gain driver that really mates well with high transconductace tubes like Eat - vintage Gec KT88's - Ei Kt90's type 2 - Shuguang Treasure Z's and possibly the new Shuguang Psvane and TS KT120's.
Caution Tube rolling can be addictive and expensive. Yes Im a tubeaholic hehe. Tu Be or not Tu Be
Agree re the Telefunkens; my favorite tubes of the 12at7 and 12ax7 variety. I would like to add a comment about the perception of spectral balance that you might find useful. Notice also the comment about the great midrange of the Tele's. I completely agree. To me the Tele's are the most refined (real like live) sounding tubes by far. But their full sounding midrange and bass in my system can sometimes create a perceived net effect of less brightness. Just food for thought. When I think "more zizzle" (but still pretty good overall) from MY stable of tubes IN MY GEAR, I think Phillips Miniwatt SQ 12at7, and Sylvania '60s vintage green label JAN 12at7, and Raytheon 12ax7 black plate.
I'm still only a third or so of the way through the "break in" period of my amp (300 hours...gives me a reason to live!), after which I'll be more able to decide what, if anything, needs sonic tweaking. The dude who designed the amp is a fan of old tubes like the Phillips Miniwatt, etc., so it will be interesting to see what this stuff sounds like.
Man...the 502p sounds damn good as new (getting better every day) even without the use of this collective wisdom, so once I digest all this and cram some new glass into the thing it just might sound TOO good, thus giving me nothing else to do. Except maybe asking "Johnsonwu" to completely rebuild it. I've been using tube guitar amps since the 60's and like most professional musicians life seemed too short to worry about tubes...you just want the things to keep functioning (for interested guitar players: my current fave amp is a really sweet Reverend Goblin 5/15 with a Jensen Neo 10).
I am wondering if the Jolida transformers can handle KT120s...anybody have a clue? Well "Wilson667?" Come on man...do it! I do plan to talk to the Jolida dudes more about that.
Wilson667...good question...if yours is a couple of months old it's likely a current version, although of course I have no idea. On mine the labeling on the front has the silk screened Jolida name and a small gold logo badge, unlike any pics of them I've seen. The bias screws are even with the bias leds...I was told they sound a little more dynamic now, but I have no clue what makes them different other than what little specific info I've gleaned from talking to people at Jolida...I suggest you call 'em.
Also, reading that somebody has had bad luck with EAT tubes strikes me as amazing...at nearly $1400 for a "quartet" of 'em...man...
though. I have read that the KT90's tend to have a more solid state sound and less of that tube warmth. I am sure someone will let me know if I am wrong.It could depend on the KT90. I have the Ei KT90 type 2 and with the stock input tube they sound 'steely' in the highs. With the 5751 input the Ei's are amazing. And the power WOW. So I will say with the right compliment of tubes they sound very powerful and tubey. I haven't tried the EH KT90's.
As far as the Eat's the tubes that have a serial # that starts with 'D' had the most trouble. The pair I have that start with 'E' and they are rock solid. Just received some Gec KT88's and they sound very close to the EAT's.
Another great tube but very different (IMO the most 'tubey' sound) is the original Tung Sol 6550 solid black or grey plates.
found some info on KT120's at the TC tubes website
"KT120 substitution notes
The KT120 tube is one of the more exciting developments in new production vacuum tubes. Generally speaking it is a drop in replacement for 6550, KT88 and KT90 tubes, as long as the larger bottle fits in your chassis. This tube also draws more filament current (100-300 mA more per tube) than 6550/KT88/KT90 tubes do, so you need to be sure your power supply can handle the increased demand.
Many people report improved bass response and increased output with KT120 tubes. The reason for this stronger response is obvious when you look at its test results. New production 6550 and KT88 tubes we test range from 90-140% of the expected value for mA and Gm. Under the exact same operating conditions (500v plate, 300v screen, -30.5v bias) the KT120 rarely tests lower than 125% and can test as high as 185%. (We reject KT120 tubes that test higher than 165%--at some point you have to say enough is enough!)
Most fixed bias amps have enough range to dial KT120 tubes in to the recommended current draw for that amplifier, though some do not. Even if you are unable to bias the tube all the way down to the recommended current draw you can probably still use KT120 tubes. You'll just have to do a little math to be sure the tubes are running safely. Simply take the plate voltage and multiply it by the current measured in mA. For example, if your plate voltage is 500v and you are measuring 70 mA across a single tube then the math goes like this 500 x 0.070 = 35 Watts. Since this is a 60 watt dissipation tube and the rule of thumb is to run tubes at 65% of their maximum dissipation (60 x .65 = 39 Watts), 70 mA across a single tube in this case would be just fine even though the manual is likely to recommend 50 mA for a 6550 tube.
If you have an autobias amplifier you will want tubes at the lower end of the spectrum of KT120 tubes."
Wolf. You may still need that vacuum cleaner. If you put your glass bulb and wire near a Lana Del Ray song the air will be bored to death or lulled to sleep. At least that is what happens to me when I hear or see that Video games song performance. The air may not entirely sucked out of your custom tubes. ;)