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In Reply to: 12AU7 as a buffer - suggestion of brand/model. posted by beppe61 on February 13, 2007 at 23:42:41:
beppe61,I don't know the particulars of the circuit and which tubes are suitable, but it is probably best to use a 12AU7 or plug in variant. the 12AU7 can have a number of designations according to certain parameters of noise and ruggedness:
12AU7= ECC82, E82CC, 5814A, 6189, 7316
- there is also the 5963 which may or not be suitable as it's electrically a bit different. Personally, I would wait for some experience before going off to the marginal types.
In your preamp, I don't know what qualities the tube should have sonically, but my thought is to try perhaps three good, tested NOS examples. I tend to like the tougher models like these 12AU7s:
> Siemens and Halske triple mica 5814A > a very lively, detailed, punchy one, solid bass. This is my favourite 12AU7
> CBS black plate, stirrup getter 5814A > extremely refined, smooth, and a nice clear bass
> Amperex/Philips/Valvo E82CC > very nicely balanced
> RCA "Command" 5814A > good all round sound
> Philips/Amperex/Valvo 7316 > quite amazingly good- and even more amazingly expensive if the early long plate version!
> Philips/Amperex/Valvo ECC82 > really the standard Philips made ECC82 from the early to late 60's is just fine all round. I'm not sure the extra cost when it's labeleled Amperex "Bugle Boy" is necessary.You may see recommendation for the RCA "cleartop" 12AU7. This is a lively one that's very good in sleepy vintage gear, but may be a bit bright in a modern preamp.
The "Philips/Amperex/Valvo" is because the Philips company produced the same tube- same design and tooling in various factories and labelled them several ways- confusing. Fortunately, thePhilps tubes have little codes etched in the glass that tell where and when the tube was made. If you shop for anything Amperex/Philips you might get used to these codes and varify them. I recently bought a Valvo 6189 that was said to be from the Philips, Hamburg factory which turned out to have a code from LaRadiotechnique in France. The relabelling of tubes is very complex and it's important to know what you're listening to!
This is a little confusing as the various models have subtle differences in construction and the tubes of the same maker and model can sound different when made at a different time.
The 12AU7 for some reason has become expensive lately, but as you are using only one, you might try three or four and resell the ones that didn't please you. If you are not experienced with buying NOS, you may want to contact a dealer that likes to chat and buy tubes that are really well tested. The price may seem substantially more, but in reality, you will spend less by having tubes that are know to be good. It's possible on Ebay to spend a lot of time and money on tubes that are noisy or defective, though there are a couple of reliable sellers on German Ebay. I'm not sure, but there may be dealers that would allow you to try and return the unwanted ones- perhaps with a restocking fee. You may want to contact our friends Jim McShane and Kevin Deal for recommendations and ask about a return policy of some kind.
Scriva prego ancora e dicaci che cosa.
Cheers,Bambi B
Follow Ups:
Thanks a lot for the very helpful advice.
I have checked and the present 12au7 is a National.
Are the tubes you mention a remarkable step-up in comparison to National ?Thank you very much indeed.
Kind regards,
beppe61,You're very welcome. I should like others to benefit from my painfully expensive tube experiences (someday I'll write a tragic poem about the 6DJ8) and avoid my mistakes!
With regard to your National 12AU7, that is a rebranded tube that could be from any maker old or new. I have a pair of National 5814WAs (the "W" means tougher). I bought these about four months ago for $3 each and wasn't sure at all who made these as they are black plate, halo getter with extra mica support rods, a small tringle in between the pins. But, the mystery was solved as these tubes are identical to a pair of 1961 RCA "Command" 5814As. National had apparently sandblasted the RCA etched type code off- and poosibly when this tube was already 30-40 years old!
It's possible that if the National 12AU7s arrived in your preamp new, it is a modern production tube. Makers have to have access to enough tubes to be able to supply a consistent sound, but it could like my National 12AU7, be a selected older NOS with a new label.
Agian, I don't know the kind of sound to expect from your preamp and no tube can be an absolute recommendation as the same tube sounds differently in each use. I can't say for certain if my 12AU7 suggestions will be better than the current one, but if you try a range, you would know!
I use 6- 12AU7s amd all in vintage gear: McIntosh MX110, MC240, Scott 330D tuner, and McIntosh MR67 tuner and I probably gravitate towards "faster" punchier 12AU7s as I want to "wake up" the vintage sound which -after awhile- can be too thick and warm for me. You may find you it interesting to try both the "fast" and as well as something less agressively energetic.
I keep a detailed list of tubes so I know what I've purchased:
12AU7 [6] 1, 2, 2, 1 TOTAL: 674- Philips SQ/ by Siemens 5814A -3 mica- NOS
5- Brimar ECC82 "cleartop"- GB- NOS
2- Sylvania JHS 12AU7WA- 6189- NOS 66
1- HP/ Amperex- Holland- NOS
1- HP/ RCA- cleartop-US- 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- US- NOS
4- CBS 5814A- blk pl- sq gtr- NOS/Used?
8- Sylvania 5814A- USA- c.1970
2- National 5814WA by RCA- black plate, halo- US- NOS
3- Siemens- E82CC/6189- 2 mica, halo- Germany- NOS
4- Siemens 5814A -3 mica- USED
1- Valvo 6189- RTC- France- double getter sup- NOS
8- Valvo ECC186/7316- Holland- 1965- NOSAnd really, this shows the silliness of NOS collecting as it took 10years and many Dollars- notice I have nearly 70- 12AU7s for 6 positions, to learn I could probably be happy the rest of my life with only the Valvo 7316s- which I purchased only a few weeks ago! This is where this site and a communicative dealer though can help narrow choices from the many, many options.
But, tubes can be seen as an "artist's pallette" to shape the sound- it's remarkable how much some equipment change with tube changes- towards a certin direction and I expect I'll fuss and try these for a long time!
Cheers,
Dear Sir,
thank you very much again.
Let me please quote the following words of yours that sum up perfectly my intention:
" I probably gravitate towards "faster" punchier 12AU7s as I want to "wake up" the vintage sound which -after awhile- can be too thick and warm for me "
this is exactly my situation ! I am looking for a punchier and faster 12au7 tube indeed, even if it will be a little "solid state" sounding !
" You may find you it interesting to try both the "fast" and as well as something less agressively energetic "
No. I am already determined to get a more "energetic" sound.
I am using my stereo also for ....ehm, home theater purposes (please excuse me).
In the end, among the 12au7 that you have tested which would you characterize as the most energetic ?
One last thing.
I have found a Sylvania and a Philips Miniwatt in a closet.
Are these energetic ?
A friend of mine has a also a Mullard that I could try.Thank you very much indeed !
Kind regards,beppe
Beppe61,It's difficult to make an exact prediction of the qualities a particular tube will exhibit in various places.
It seems to me the 5814A is consistently the more energetic 12AU7 variant. And the most energetic I've tried is the Siemens triple mica 5814A. While very "fast" and almost percussive it maintains wonderful detail and openness. I like a particular kind of bass that is strong, but very transparent and has a natural timbre- a double bass sounds very distinct from say an organ, and the Siemens is very refined in this respect.
The other choice might be the RCA "cleartop" or sidegetter 12AU7. I've never tried this one in a modern preamplifier, but it is certainly a tube with a strong character. Some have commented the RCA cleartop as being a bit bright on the top end, but it may suit you as it's fast and the top end is strong but not harsh. This is why I like it so much for sleepy old McIntosh. The cleartop is fortunately quite common and NOS are not terribly expensive, so you could try it for comparison.
Finally, if you can find a good one at a reasonable price, the Amperex 7316 (or ECC186) is probably really the best balance between very fast and dynamic and still very natural and open. There are two or three slightly different ones with the early D-getter, long plate considered the best sounding. The 7316 is expensive now, but again a you are using only one, the $40-100 might be well worth the price.
I would say that a typical Sylvania 12AU7 will be going somewhat opposite to your intention- it will be a bit softer and more forgiving. The Sylvania JAN 5814A- late 60's grey plate though is probably under-rated, not bad at all- quite good for someone after a bargain. The Mullard ECC82 is, to me, a tube with great mid range but not particulary energetic. This is true of a typical Philips ECC82 like your Miniwatt- these are very well balanced and seem to work well everywhere, and are nicely neutral.
Certainly, I would try every 12AU7 that is at hand- the Sylvania Miniwatt, and Mullard, and this will gain some experience in the various sounds these tubes make. I think of tubes a bit like vintage wine- to narrow the desirable ones from so many choices, a person has to try a lot of kinds with various music and develop a memory for the small differences in sound.
Cheers,
Thank you very much again Sir.
I sincerely think your kind advice is very helpful to me.
Moreover I feel we have same taste on music.
I would like that mantains the "percussive" nature of bass, as you very well say. And of course with transparency.
On the basis of your words I will be looking for a "Siemens triple mica 5814A" in the next days.
I really trust in your very wide experience.
For now I have put the Miniwatt in.
Not bad but I just want that Siemens !My kindest regards,
beppe
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