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Dear Sirs,I am using a commercial preamp the line stage of which is nothing more than a pot followed by an 12AU7 wired as cathode-follower.
The original tube is unbranded.
The sound is natural but soft and weak on bass.
I tried a Telefunken 12AX7 (ok is not the same tube) and the sound is stronger, clearer but also it seems a little distorted.
So I am here to ask:
1) could some run in improve the sound with the Telefunken tube?
2) should I use a real 12AU7 and which ?
I do not like a too much soft sound.
I like the sound with the Telefunken but as I said I also perceive some distortion.Thank you very much indeed.
Kind regards,beppe
Follow Ups:
Someone previously mentioned the Tung-Sol 12AU7 (the older variety from the 50s) and my experience with them mirrors his. I would describe them as having a very solid bass foundation and a rather big sound. One of very few notable 12AU7s in my experience. The whole 12AU7 family of tubes suffer from mediocrity.To address the lack of resolution and liveliness, I would suggest that you roll the 12AX7 tubes in your pre section, if it indeed does use 12AX7 tubes. I think the potential to change your sound more toward your preferences rests with this tube as opposed to the 12AU7.
Thank you very much Sir for your kind and valuable advice.
My preamp has a phono section (2x12ax7) that I do not use and I took out the tubes.
My concern is with the line section, just one 12au7.
I want in that position a tube with a powerful and fast bass.
If I understand well the Tung-Sol 12AU7 can provide that.
Thanks a lot and kind regards,
beppe61,Although you are not using the phono stage 12AX7s, the power supply of the preamp "expects" the load- you should keep tubes in those spaces. I don't know the implications of leaving the sockets open, but it may throw the power supply out. I hope others will comment
Certainly, no one wants to waste nice NOS tubes that aren't being heard, so I would recommend buying a couple of Sovtek 12AX7LPS to fill the spots. The Sovtek LPS is actually quite good for a current 12AX7 by the way.
Cheers,
Dear Sir,
thank you very much indeed for your extremely kind and helpful advice.
I did not know about this risk.
I will put 2 tubes in the empty sockets.
Is it possible to keep the 12ax7 in the line stage or I will burn it very fast ?
The bass is very solid indeed.Thanks again and kind regards,
beppe
.
Please excuse me again but I have elaborated my impressions.
I am now looking for a 12au7 tube with a good drive, even if this comes at the expense of musicality.
A very robust sound.
Any suggestion ?Kind regards,
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
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
You will probably wreck the 12AX7 in this circuit unless you adjust the cathode resistor or the grid bias resistors. The 12AU7 can take 10mA current where as a 12AX7 will withstand only 1/3 of that current. The 12AX7 sound is most likely full of the even order harmonic distortion that an underbiased tube has, which is why it will sound both pleasing and distorted.
_______________________________
Long Live Dr.Gizmo
Please excuse me Sir, are you saying that I am stressing the ecc83 and eventually I will destroy it ?
I am a little worried because is a quality tube I understand.
A real NOS Telefunken ....
Please could you elaborate ?
In the meanwhile I stop using it.Thank you very much indeed.
Kind regards,
If the circuit (Supply voltage, cathode resistor, etc...) is designed for a 12au7, a 12ax7 will have to much current flowing through it. To use a 12ax7 in that circuit, the circuit needs to be redesigned first.Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Thank you very much indeed Sir.
A very stupid move I did.
Now I understand that the au7 ad ax7 are not equivalent.Kind regards,
Hi ,
If it's just for a buffer a higher transconductance , higher mu valve such as 12AT7 , 5965 or E80CC should be a much better option to a 12AU7cheers
Thanks a lot Sir.
Are they perfectly equivalent to a 12au7 ?
I am not able to mod the circuit I am afraid.
Kind regards,
Hi ,
Not a perfect equivalent but the same pinout and worth a try . 5965 is probably a good start as these are very cheap . Good luck :)ps 6211 is another
cheers
Thank you very much Sir.
Please excuse me again but, from a safety point of view, I should not have any problem I hope.
I mean, no flames no tube burn-out etc.
I am very ignorant in the field.
Do you think that the sound out of a 5965 or a ps6211 tube could be characterized as energetic, aggressive ?
My present tube is too soft and flat.
I like a more aggressive sound even if this could imply some loss in musicality.Thank you very much indeed.
Kind regards,beppe
Hi ,
I very much doubt there will be any flames . Have you consulted the manufacturer of this unit regarding the use of alternate valves ? I am not too familiar with the sonics of 5965 or 6211 unfortunatelycheers
Thank you very much Sir.
I will look for those tubes then.Kindest regards,
I agree but don't you think the circuit will need some re-working assuming it was designed for a 12au7?Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Hi ,
It worked with a 12AX7 so should be ok with the suggested valves which are a lot closer in specs .cheers
Both of the first two are available in the EU. They are pretty nice-sounding tubes. See: http://www.artsandmedia.com/5965.html for more info on these tubes.
Please excuse me Sir.
Are the mentioned tubes perfectly equivalent to a 12au7 ?
I understand that I was stressing the 12ax7 tube, that is not equivalent.
By the way, what a bass !Kind regards,
But as fatbottle pointed out that might not matter if it is just a buffer. I just gave you a wider range of tubes to try than he did - all of which are higher mu.
... an RCA 5963 black plate or a Tung-Sol 12au7a. There are many to choose from and try that are not expensive.
Thank you very much Sir for your very kind and helpfuld advice.
Actually I felt that an 12ax7 in 12au7 was not a smart move.
Nevertheless I have been impressed by the result.
Maybe the original 12au7 is quite bad.
As I said the duty for the selected 12au7 is that of a buffer.
Actually I am putting down a list of very good 12au7 tubes.
Is there the problem of "fake" pieces with them as with Telefunken NOS tubes ?Thank you so much sincerely.
Kind regards,beppe
... pick up 4 or 5 common 12au7 variants (5963, 5814a, 12au7a, ecc82, ...) on ebay for a few dollars apiece and see what caught my attention. The different influences of the particular tube on your music will be noticed.I'd look for a seller that had several of these tubes and do a 'combined shipping' deal to save money on postage. For $25, you can get a nice assortment of good used tubes to try. If you find one you particularly like, you can then buy a true NOS of that variety.
Thank you Sir but I have already settled for a more energetic sound.
So I am looking for a very "aggressive" 12au7 tube.
If this kind of tube does exist.Thank you very much indeed.
Kind regards,
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