Jolida jd-502p

Anyone using 5751 tube to replace 12ax7's in a Jolida. I have read that it may not work well with some circuit designs. Also curious about what other Jolida users are using?
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They work fine. Will you like them better? Give them a try.
I would simply try them out. In virtually every instance that I rolled a 5751 in for a 12AX7 it worked. The different sonics may or may not appeal to you but I really like them. You may want to start with recent production NOS JAN 5751s from the 80s they shouldn't cost very much. It will give you an idea of what the better ones sound like. Have fun trying them out.
The 5751 is simply a lower gain version of the 12AX7. It will not do any harm in the circuit and is a direct replacement.

Like it better? Only you will be able to make that decission.
Thanks everyone for your responses. I did get a chance to
hear a pair of RCA JRC- 5751WA the sound was was nice and open with a good sound stage and nice separation but very little bass.In other peoples experience do the 5751's typically lack bass. Is there another tube that I might try to get a little more bass?
Try the GE TM gray plate 5751 from the 50s. The bass is prodigious in my experience and several friends as well. The Sylvania 2 mica Gray Plate 60s tube also has more bass than the RCA BP. As far as 12AX7s go you will prolly have to go with true Mullard Blackburn long plates "IF" you can get decent ones. They seem to emphasize bass. Failing that specific tube try any other older Mullard production.
Hi Wilson667

What 12AX7 or 5751 tubes did you get to replace the existing 12AX7 tubes in your JD-502p? Also is your JD-502P the stock or upgraded one from Jolida?

I am still not settled on what 12ax7 to use. Shortly after this thread my phono pre had to go to the shop. It was and still is my only source and does double duty as my preamp . I did not get to listen to any music other than through my tv.Now that it is back I hope to get this sorted.So for now I am using some sovteck 12ax7 the tung-sol that came with it and a rca jrc 5751wa of those I think I like the sovteck best.

I bought my 502 used here and the person I bought it from did not say if it was upgraded and I did not ask.So shrot of opening it up I have now idea how to tell.Sorry I could not be more helpful.
Is the Sovtek the LPS variant. Those have a good reputation for being clean and quiet with high gain. They are not known for their Bass however which is kind of interesting. Since it is a phono pre I think you may just be better off with carefully selected current production tubes. NOS tubes are just not plentiful enough to find really quiet ones, with a couple of exceptions like Upscale, new production tubes can be screened in large batches and thus as a rule can be super quiet. If you can afford them the GL reissues are getting some good reviews for their tone. They should still be less than really good NOS. Jim McShane over on Audio Asylum can set you up with good ones.
Thanks for you response. The Jolida jd502p is a tube power amp, my phono pre is a PS Audio GCPH and is solid state.The sovtech I am using is an LPS and it came from the previous owner so I don't know if it is an early or a recent production tube.I believe I read somewhere that the ones from the eighties were the more desirable ones.
I think Sovtek 12AX7 LPS tubes are "curent" production. In any event I consider them as current products. I know some are now speaking the virtues of Russian Old stock.
Hi Wilson667

I can't find that other thread where you were mentioning getting a quad of KT-120 tubes custom matched by TC Tubes. I'm thinking about this as well but then I found for the same money one could get a cryoed quad of KT-120s. I then also found factory matched tubes for about $25 less. Ugh. The decisions. I'm wondering which would be better.

Also if you try to get in touch with Jolida to find the plate voltage info etc for the TC tubes matching it is better to call them. I e-mailed them some questions and it took a couple of days for them to get back to me. They must be really be busy.
Just an FYI

I contacted some tube sellers regarding 12AX7 alternatives for the Jolida JD-502P. Here is what they told me. I'm just sharing info.

suggestions from Brent Jesee:

12AX7 Mullard UK made OEM labels, 1960s

12DF7 industrial low noise 12AX7, Westinghouse 1960s

12AX7 RCA made for Tung Sol long greyplate, 1950s

"Again, these 12AX7 tubes will deliver the sound you want. The 12DF7 is probably the best bargain here."

Suggestions from Jon @ thetubestore.

Preferred Series 7025

Northern Electric 12AX7

These tubes are out of my price range right now. For my 502P I'm trying matched and balanced Tung Sol re-issues now. Later I'm going to try JJ preamp tubes and then Penta low-gain 12Ax7 tubes from Doug's tubes. If I can get quality NOS tubes that are a bit easier on the wallet then I may give those a try.
I'm poking around for Jolida input/driver tube options also...Just to throw some other opinions in there, Michael Allen at Jolida likes the (expensive-ish) Phillips Mini Watts, and Jolida Jerred likes GEs. I have reservations about buying older NOS or "used but tested" tubes only because of inconsistency issues (although likely not an issue) and the fact that those little socket wires often look shopworn and corroded. Maybe an easy fix but bugs me. I'm looking at new versions of various things that are both high gain and quiet but maybe sound different than the stock Tung Sol/EH that came with the 502P. Gold Lions maybe...or those Psvane versions. Again, so many opinions that I get dizzy, but I'll try something eventually.
I strongly urge you to do some reading on 12AX7 tube spec regarding Max heater to Cathode Voltage.
The spec says 100V.
SRPP based configuration calls for a raised filment to avoid this stress.
Jolida does not have raised filament, just an AC supply with a grounded (vs raised) center tap.
Your prized vintage tubes will have one triode in each tube aging real rapidly.
The $$$ wasted on premium vintage tubes can buy you properly designed amps.
First, I'm no gentleman. Second, instead of wasting my $$$ on vintage tubes I'm merely enjoying my inexpensive, although perhaps not properly designed, Jolida. Apparently the rapidly aging triodes sound great. Who knew? WU KNEW!
Hi Johnsonwu

Again my posts are never as funny as Wolf's but here goes. Thanks for posting the information you did. You saved me at least $100 on vintage 12AX7 and 12AT7 tubes. (More money for records now!) Even if I read the 12AX7 specs I never would fully understand it and I definitely would not have known about what you said about the Jolida. I had to google what SRPP meant. I'm sticking with the 502P as a CJ Classic Sixty SE is still way out of reach for me.
I can tell you from personal experience how much better a Jolida piece I once owned sounded after I rolled the tubes. At that time it was expensive but clearly not as bad as it is now for the better truly strong old stuff. I used Upscale Mil Spec Mullard CV 4004s. The impact on the sound was so great that I found it unlistenable without those tubes in place. That was before the advent of all of the reissue 12AX7s. I like them as well but still imagine that the improvement made by true Mullards is worth the investment. If you can somehow borrow a friends NOS tubes I think you will understand what I am saying. Ordinarily I would tell you to use 5751s but unfortunately the one and only circuit where they simply did not function was the Jolida.
I used 5751s in my system to great satisfaction when I was using monitor speakers. I later moved to full size speakers and the system sounded flat. For the larger speakers I went back to the 12AX7 tube and it provided significantly more dynamic performance.
Jedinite24 makes a good point about Jolida in general...other amps I've looked at (and some I've actually listened to) are from VTL (85), Conrad Johnson, Cary, Rogue, and even a Tim de Paravicini EAR thing...all sell for multiples of the Jolida cost, and are they better? I'm not so sure...heresy yes, but really...the 502P sounds amazing.
Everyone likes what they like and if the Jolida makes you really happy why fight it. I say this because I imagine you have heard other makes of audio gear and are not naive. My own thoughts are that there are many better sounding pieces around including the EAR.
I use Chinese amps that are truly giant Killers. I honestly think their sound is about as good as it gets (in my system). They will never garner the respect of the mainstream audiophile community but I don't care and for the price paid they are simply ridiculously great.
I hardly "fight it" (the low cost excellence of the 502P)...I think I celebrate it! (ad nauseum maybe, but I prefer enthusiasm to cool). I use a Chinese Kavent S-33 (before going out of production it was built alongside Vincent stuff) that is a Giant Killer so I'm hip to great things from our Chinese brothers, without whom I'd have paid several times over what my rig cost.
Wilson - I'm a JoLida fan. I used Ei Elite 12AX7s and NOS Mullard 12AT7s with Winged C KT88s in mine. Never tried 5751s. You might want to check out Tube Monger if you haven't already. They have interesting stock and possibly some suggestions for you.
Thanks for the tip Ghosthouse. I hadn't heard of tubemonger. I checked out the site and they have quite a bit of NOS tubes that are a bit different than what I saw on other sites. I shot them an e-mail about my JoLida 502P and the power tubes I'm going to use with it and to my surprise I got an e-mail reply back with suggestions a couple of hours later. Here is the suggestions I received:

12AT7 tube suggestions:

Siemens & Halske E81CC - 1966 MINT NOS 3-MICA 6201 Munich W. German Prem. ECC81 12AT7 (neutral and very musical)

BRIMAR CV4033 - MINT NOS 1960-62 Military Black Plate Prem. Grade Long Life ECC81/CV4024/12AT7 Halo Getter STC Prod ENGLAND Factory Tested (more British sound with emphasis on midrange)

12AX7 tube suggestions:

MULLARD CV4035 M8214 - MINT NOS NIB 1961 Military Box Plate Prem Grade Long Life M8137 ECC83 CV4004 12AX7 Wrinkle Glass Halo Getter Whyteleafe Prod. Dual Logo Old Shield and CV - Gt. Britain (rich midrange)

BRIMAR CV4035 - MINT NOS NIB 1961 Military Box Plate Prem. Grade Long Life ECC83/CV492/CV4004/6057/12AX7 Halo Getter STC Prod. ENGLAND (neutral and very musical)

Tungsram ECC83 12AX7 - MINT NOS NIB OCTOBER-NOVEMBER 1970 - Hungary (great tube at midprice)

Between Brent Jessee's recommendations and tubemonger's recommendations NOS tubes for my JoLida are going to run me over $250 easily for pairs of 12AX7s and 12AT7s.
Hey Jedi - glad the site was helpful. I think you will also be pleasantly surprised how fast they deliver if you do order from them.
I also have a Jolida 502 (but the CRC integrated version). I have bass heavy speakers, so I'm set up to (I think) do the opposite of what you are trying to do, but for the record: Soviet tubes from Jim McShane for power amp [I highly recommend these economical tubes -- even though I can never remember their actual name], either JAN Sylvania 12AT7WB to tighten up the base or Ei Elite Gold 12AT7 if I want more top end sparkle, & I switch between RCA long black plates and Amperex Bugle Boy 12AX7 for the rich midrange. Good luck.

Please don't lure me into the lurid world of Old Tubes. It just seems like an network of crazed and sweaty audio geeks yanking dusty old tubes from abandoned 1950s radios to put on questionable testers while trying not to knock the painted logos off. Give me a New Sensor shiny glass product instead!
Although Philips "Mini Watts" are on my short list of things to try that so wrong?
Wolf, I agree on trying small signal 8-pin and rectifier tubes of a vintage era. As far as power tubes there are top quality examples being manufactured and they are NEW with guarantees. Now tube rolling in instrument amplifiers...
I've had insane luck with guitar amp tubes...the last time one failed on me was in my Magnatone combo in 1968. This includes constant gigging for YEARS using an old Boogie, a HiWatt, a 1960 blonde Bandmaster, various Twins, Marshalls, etc., etc... I had a 1960 all original brown tolex Deluxe that I used as a studio amp seemingly forever and finally changed some leaky caps and it sounded exactly the same. I mean really...all the effort used by me and everybody else to isolate and pamper our hifi stuff, and I watch an airport lunatic drop a Twin Reverb in an Anvil case 10 feet out of an airplane...that amp worked perfectly for about 6 more years until I sold it.
Very enjoyable read of your equipment experiences. I was always amazed at the rough service and neglect guitar amps would accept. Mine have been in storage for a few years except for my Tweed Champ, so some may just die of a broken heart by being ignored. Of course my trusty vintage Variac is ready for their release. They are finally up for parole soon.
I should add the amplifier that I had (still own) owned the longest and played the way most as a "pseudo" pro, but also with much jam time, is a 65' Super Reverb. For a long time I owned one amp and one guitar, 59' LP Custom (still have). Upon purchase amp went to my technician, made "healthy" then a slight mod. Guitar would plug into the non-reverb channel, tho the reverb would work. A toggle switch in the back (no one knew about, HA) and both channels would link together. EVERY knob in effect!! It could scream, a Marshall killer! The other guitarists who want to dominate the volume, you know the types, would just scratch and shake their heads!! My point.. is that it could be extra rough on tubes. Still never a problem. Replaced power tubes once after years, tho the old ones never failed. Original speakers also never a problem, either. Amazing!!
Wolf don't you think "lurid" is a bit over the top. I like tube rolling mostly with old stock which has had it share of dissapointments. I do agree that the may be "pulls" and there is a flow of trading some which are indeed bad tubes until someone puts and end to it. If you can tolerate the chance issues, the rewards using old stock tubes can be enormous. I have a lot of fun listening for the differences the various tubes contribute. Some tubes are more reliable as old stock than others such as 6SN7s which are prone to microphonics but are usually good. The economics of rolling NOS/OS tubes are difficult to defend, but if you can afford it....
As far as power tubes go there is no sense in trying to find old stock that is still good, it is really almost a pure collectors market at this point.
Mechans...yeah...lurid is extreme as sometimes is my humor (only in the context of an often tedious forum) ...I'll change it to "tawdry." And besides, I'm into it anyway and I can afford it, but I tend to prefer "newer things I can break in myself." I admit that like other tube heads I sit there and think, "hmm...what would a dusty Bugle Boy sound like in there?" And who doesn't want to announce at a party that they scored a pair of Bugle Boys? Like when I "pounded 6 Circus Boys" with my girlfriend (Circus Boy wheat beer from Magic Hat). I've already got 3 sets of output tubes for my Jolida, and you can bet the small tubes will be piling up too.
To any Jolida amp owners out there.

What power conditioner do you plug your Jolida 502 amp into? I was thinking about just plugging into a 1.8 kVa isolation transformer.

Thanks in advance
I use a PS Audio Humbuster III plugged into my trusty Adcom ACE 515. Seems to work splendidly. By the way...I noticed a very small mechanical (not in the speakers at all) buzz from the 502 when using the KT120s...not a big deal...but I put the Sovtek KT88s back in (after trying the stock Tung Sol 6550s for a few days) and the buzz got smaller, and they seem work really well with the Tubestore "preferred 7025s." I keep swapping between these 3 sets of power tubes...I can't help it...I'm becoming really good with my bias meter. Considering some Gold Lion KT88s now and that will give me enough power tubes to last until 2047.
Update: I switched the speaker outs on my 502p to the 4 ohm option, put the KT120s back in (I switch the power tubes around so often that I might wear out the sockets), and the slight mechanical hum went down to nearly inaudible. The combination of the new 7025 input tubes with the KT120s is sort of, like, awesome. I'm tellin' ya...this amp is astonishing.
I love NOS tubes but I have to agree with some that they are often not worth the price. I recently bought a Jolida 502amp and I love it. Here is what I am using for tubes:
KT88 Gold Lion reissues
Mullard 12AT7 (CV 4004) I believe - I got them from the Tube Depot
JJ Electronics 12AX7 (ECC 803)

I love the sound! Great detail, tight bass yet delicate highs. I am buying another 502 and I am going to run the pair as monos.
My mistake; the 12AT7 Mullard is a CV 4024, not a CV 4004. The 4004 is a 12AX7..
Yeah man. I've thought about the mono 502p path but my speakers seem to be efficient enough to make me not want to bother...and I don't really have the room with my current rack space...HOWEVER...let me know how that works out as I've never heard anybody's thoughts on 502p monos. And I could get a different rack...hmmm...
Hi Zkidd

Definitely keep us in the look how it goes with the 502P monoblocks. What speakers do you have that warrant the power of 2 JD-502Ps? I own the Jolida JD-502P as well and am really happy with it. I couldn't resist trying NOS tubes and ended up with a whole GE Joint Army Navy tube complement in it now. In my system the differences are subtle between them when I had the Tung Sol KT-120s in the Jolida. There was a more pronounced difference bass wise and imaging wise between the GE 6550s vs the Penta Labs KT88s.

With your Jolida also check out the Tungsram 12AX7s with either gold or platinum level matching. Another Jolida 502P owner here has the Mullard CV4024 and the Genelex Gold Lion KT88s too and he was really liking the Tungsram 12AX7 match-up with all.