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I just retubed my VAC PA80/80 with the same tubes I've been using for the past five years... Shuguang KT88-98 output tubes with JJ-Tesla 12au7 short plates. JJ has a 12au7 long plate version but I can't find any information about them. Anyone recommend them?
Also, I'd appreciate suggestions for other (cheap) 12au7s to try in my VAC amp. I rolled some Jan-Philips 12au7's but didn't like them (flat, two-dimensional sound)and the original Golden Dragon 12au7's (clear sound but thin and pinched). I'm look for a clear, full sound that is round and musical. Any suggestions are appreciated.
Follow Ups:
Affordable NOS in many types has become quite problematic. AA sponsor Jim McShane shows some RCA 5963s for $16.50 each. RCA made GOOD tubes.
Eli D.
I don't know if this experience is shared by others, but it's my perception that old-stock 12AU7s, whatever shortcomings they may have, tend to last a LONG time. 12AX7s, again, based only on what I've seen, tend to wear out faster, though I can't claim to understand why.
David
Hi,
I have both versions of the JJ 12AU7. The short plates sound OK and reasonably balanced but on close listening they are a little woolly, and lacking air. The long plates are cleaner - or leaner if you like. If I had to make a pick I'd pick the long plates BUT my pair after a couple of weeks of uses started to make pop noises......So potentially OK tubes but I wouldn't buy another pair - go NOS.
Cheers,
Anthony
jtube,
I think there are many choices for 12AU7's that can better the JAN-Philips- which are probably mid- 80's, and without hearing them, I'm quite certain the JJ's and Shuguang's could be equaled or bettered as well by NOS and possibly at a similar cost or even less with patience.
My favourite ("ultimate") 12AU7s:
Z.> Philips / Amperex / Valvo 7316 / ECC186 which is refined, transparent, naturally timbred, spatial, and detailed,
X.> the Siemens triple mica 5814A/ E82CC that is punchy and energetic, detailed, smooth, and very quiet,
Y.> the CBS 5814A, which is much like the 7316, but a bit more liquid. Of these, the CBS is reasonably priced while the Siemens and the 7316 generally have gotten somewhat expensive.
If you're on a budget: I would suggest you try a pair of about 1970 Sylvania grey plate 5814A's. I bought 8 of these at $1.50 each NOS about three-four years ago- actually in order to get 4- CBS 5814As in the same lot (at about $8 each) and the RCA's are surprisingly good- quite deep and full sounding. I should think the RCA black plate "Command" 5814A, a well-made tube that I bought a couple of years ago for $4 each in the boxes would improve on any of the tubes you've used so far in your VAC. Actually, the ordinary early to late 60's Philips-made ECC82 is just fine- and there are millions around.
By the way, in my view the RCA "cleartop" -of which I have some very good Tektronix ones- is a very good tube for waking up sleepy vintage, but may be bright in modern gear. - That is speculation as all my use of 12AU7s is in vintage- McIntosh, Fisher, and Scott.
Keep in mind these tubes may last more than 10 years in your VAC- the drivers in my Audio Research D115 are the original 1985 ones- so spending $25 instead of $10 on each of 2 tubes means about $1.50 per year extra over their lifetime,..
The NOS 12AU7 seemed to have a rapid price rise a few years ago- 4?- and perhaps the guitar amp crowd discovered them, but there are still good values. Watch German Ebay for the Siemens and 7316 for example.
Happy hunting and let us know what you try.
Cheers,
Bambi B
PS: 12AU7's at Home:
12AU7 [6] 1, 2, 2, 1 TOTAL: 67 > [Notice that I use 6 but have 67,..]
4- Philips SQ/ by Siemens 5814A -3 mica- DE- NOS
5- Brimar ECC82 "cleartop"- GB- NOS
2- Sylvania JHS 12AU7WA- 6189- NOS 66
1- HP/ Amperex-- NOS
1- HP/ RCA- "cleartop"- NOS
4- RCA- 5814A- black plate 2 mica- NOS
4- RCA/ Textronix 2-matched prs "cleartop" NOS
3- Valvo/ Philips ECC82- dimp disc-Holland -NOS
1- Valvo/ Siemens E82CC- NOS
2- CBS 5814A- JHS blk plate- stirrup gtr- NOS 57
7- RCA cleartop- USED
1- Amperex Bugle Boy 7316- Holland- NOS 64
4- RCA “Command” 5814A- NOS
4- CBS 5814A- blk pl- square gtr- NOS
8- Sylvania 5814A- USA- c.1970
2- National by RCA- 5814WA- black pl- US- NOS
3- Siemens- E82CC/6189- 2mica, halo- DE- NOS
4- Siemens 5814A -3 mica- USED/TNOS
1- Valvo 6189- RTC- France- dbl gtr sup- NOS
8- Valvo ECC186/7316- Holland- 1965- NOS
-1- Siemens/H E82CC/6189- 3 mica- DE-NOS
Bambi,
Great info. I was wondering if your Sylvania 5814's are Gold Brand's or not. Sylvania tubes have always struck a chord with me. Can you give me your impressions of this tube?
Johnny
.
I would try the RCA cleartops or Tung Sol 12AX7
YMMV,
Johnny
For NOS, Grey plate and clear top RCA's are relatively cheap and abundant. In general, the long grey plate variety will sound warm with decent detail while the CT's are more on the neutral (some say bright and/or sterile) side with more high end energy. Both sound kind of crude and muddy to me, though. I'd forget 12AU7's entirely and would track down some used but good testing CBS-Hytron 5814's or Brimar 13D5's (both are drop-in 12au7 variants) from a reputable dealer. IME, they are better all around performers.
CBS Hytron 5814 or somewhat superior performer Brimar 13D5, but more subject to microphonics per others. I had no issues with the Brimars per my somewhat limited experience. I moved on to Tungsram E80CC that draw twice the filament current of the 12AU7s and simular replacements.
Absolutely agree with Pat & includes those nasty RCA clear tops in music playback amplifiers. Ok, I understand two types of clear tops exist. Crescent shape vs straight cuts in the top mica. I believe 1956 thru some 1958 RCA clear tops with 'straight cut' micas were the best. If the early clear top outperforms Tungsram E80cc or Brimar 13D5 in my amps, I will pay $100 as an 'information' fee for the upgrade. Also, in a rare case a tube can compliment the next tube downstream cancelling harmonic distortion in a positive fashion for a seriously good result. In that case, I am full of it.
Eli Duttman may be able to advise you of some late '40s or early '50s hot 12AU7 performers.
Are these also labeled JAN-Philips 5814A? I've tried them in phase inverter position on guitar amps and found them downright constipated sounding, at FIRST. They require a lot of break-in time to achieve a final "ok" tone.
My favorite 12AU7 types are: BP RCA 12AU7, BP CBS 5814A, TFK ECC82, Philips/Miniwatt SQ 7316, Mullard/Amperex ECC82, BP CBS 7318, Raytheon 12AU7A.
Really haven't found a recent made 12AU7 to match the tone (esp sweet, clear midrange) fo the older NOS types listed.
FL,
Did you use a 5814A in a PI that normaly calls for a 12AT7 or 12AX7?
If so, with that gain reduction, it will sound constipated.
?????
jstrm
J, tubes went into an Ampeg VT-22 combo. The amp came OEM with Sylvania 12AU7 in PI slot. Though I've used CBS 5418A or 7316 in some Fender amps (eg: tweed Bassman) with pretty good results. Tad more Bluesy tone than stock 12AX7 or 12AT7's. Not really constipated, more slow onset of overdrive and distortion than 12AX7 or 12AT7.
I find amps with 12AU7 PI are a bit easier to adjust the range of tones. 12AX7 PI give faster, crunchier overdrive. Constipated tone generated by the gain stages can often be traced to amps that have the gain stage tubes not optimized (improper plate voltage or cathode current draw). I must admit 12AT7 PI amps are the least amenable to tonal changes through the volume range, in my experience.
FL,
AhHa! That makes perfect sense. I read an interesting paper about the 12A_7 family and the relationship between gain and freq response. The 12AU7 showed a much wider range than the others, IIRC. I wonder if FEIC ever experimented with them?
Thanks for your good response.
jstrm
You know, I don't think I've ever seen a stock OEM Fender amp with a 12AU7 ANYWHERE in the circuit. It could simply be that Leo had a bunch of 12AX7, 12AT7, and 12AY7 to play with or he couldn't get a good deal on gross amounts of 12AU7. That's how it seemed he made his amps. Around parts he had aplenty or ones which were easily & cheaply available, at the time.
Yes, they're the JAN-Philips 5814A variety. I put about 30 hours on them but just couldn't warm to them.
Jeff, shoulda mentioned that the last time I tried the JAN-Philips 5814A was on an Ampeg VT-22 amp that puts +250VDC onto the plates of that 12AU7. It didn't sound good, at first. Ok midrange to highs after 2 weeks. Never good bass.
I replaced it with a CBS 5814A. Much better bass and bass to midrange. Clean highs.
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