12AT7 Tubes

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avahifi

12AT7 Tubes
« on: 13 May 2003, 02:48 pm »
Hi:

We have noticed some discussion on using various tubes in AVA equipment, particularly Mullards.  We decided to try some different tubes ourselves to see what we liked best.  What follows is the results we found.  Please note that we tried a couple of the tubes we have been hearing about, but have not tried "every" brand available; rather, we took a sampling of tubes to see what we could hear.  There are other tubes that people are using that will undoubtedly have characteristics different than the ones we tried.

One of the basic things we aim for in designing audio equipment is to accurately reproduce the sound as it was recorded.  We don't want to shape, modify or alter the sound.  We don't design our equipment to work better with brighter speakers, or duller speakers.  We don't design our systems to have a warm sound, or a cool sound, only to be as accurate as possible.

The same rule holds true in our solid state OmegaStar series, our tube/hybrid Transcendence Six, and our FetValve/Transcendence 7 equipment.  The underlying technologies of each, however, dictate how far we can go in reaching total accuracy.  We do not, however, limit our engineering in any one product line in favor of another.  Simply stated we strive to bring you the best product at a very reasonable price.

Please note that we understand that people like different sounds and that a particular brand(s) of tube gives them the sounds they like.  We have NO problem with that!  We also know that people have a variety of equipment and speakers.  Further, we understand that speakers have a character of their own, some may be bright, some lacking lows, etcetera, and that tubes can help in shaping the sound to a person's liking.

With all this in mind, here is what we found in our reference system consisting of a Transcendence DAC, Transcendence 7 preamp, FetValve power amp, and Biro L/1 speakers:

Electro-Harmonix 12AT7EH:
This is the stock tube we have been using since we introduced the Transcendence 7 last year.  The EH is the most transparent and neutral tube of the batch.  The midrange is very clear, dynamic, and transparent, without an overly warm "tube" sound.  The bass is controlled and reaches nicely.  The highs are good and clean with no edge.  The midrange micro dynamics are very good.  The EH has the least amount of coloring.

Amperex 12AT7:
This new old stock (NOS) tube has a warmer "tube" sound.  The midrange sounds were very lush and generally pleasing. There was a loss of bass control, with the lows not extending as far as the Electro Harmonix.  The highs also didn't reach as well as the EH.  The midrange micro dynamics were good.  For those looking for a more romantic or warmer sound sometimes associated with tubes this is appears to be a good choice.

Mullard 12AT7 / CV4024:
The NOS CV4024 Mullard was our least favorite tube.  The overall sound was shallow, with a significant loss of transparency over the Electro-Harmonix.  There was a loss of bass control and reach.  The sound has an overall brightness that bordered on steely and harsh.  Most important was a big loss of micro dynamics in the mids which resulted in the shallow sound.

Mullard 6201 (gold pin):
The Mullard 6201, also a NOS tube, has a bit of the warmer tube sound.  The mids had good micro dynamics, but there was a bit of lifting in the upper mids.  There was also a bit of loss in the bass.  The 6201 was a good tube, but for the "tube" sound we preferred the Amperex.

Philips JAN 12AT7 NOS:
We did not test this tube in comparison with the Mullards or Amperex, but we have compared it in the past with the Electro-Harmonix.  The Philips lacked a lot in detail.  The transparency of the tube was significantly less than the EH. There was a loss of both the lows and the highs.  We found the Philips JAN to lack too much detail.

Note that the use of a particular brand of tube may give you different results depending on other hardware and speakers.  For example, if your speakers are a bit soft sounding in the highs a tube like the Mullard CV4024, which tends (at least the ones we tried) to be bright, may give you good sound.

An interesting note:  Both the Mullard tubes had a strange startup.  When the power was first applied to the tube the filament of the tube glowed very bright for an instant before settling down to the normal luminance.  I have seen this in the past with tubes in other electronics.  I'm not sure what negative things this is doing to the tube, but it might be possible that the service life filament may be shortened.

Based on our testing we liked the Electro-Harmonix tubes the best because they are the most transparent and offer the least amount of coloration.  We felt the EH stayed the closest to the source.

We also know that some people like the soft romantic "tube" sound.  After evaluating the tubes we have decided to offer the NOS Amperex 12AT7 for those that want the tube sound.  We felt the Amperex had the best micro dynamics outside of the Electro-Harmonix.  While there was a loss in transparency, and the lows and highs didn't reach as far, we found the sound properly balanced and very easy to listen to.

If you place an order for one of our tubed products you can select either the Electro-Harmonix 12AT7 or the Amperex 12AT7 tubes.  Please note, however, that the Amperex tubes are new old stock and we will offer them as long as the stock is available.

As stated above this was not a test of all the possible combinations of tubes.  It is not our intention to alienate one brand of tube over another or to discount the experience people are having with a particular tube.  We fully agree that tubes have a different sound and that each person has his or her preferences.  Our goal was to identify a tube that allows our customers a warmer tube sound if they want it.

Thank you for your interest in Audio by Van Alstine products!!

Larry Jenkins

Beezer

12AT7 Tubes
« Reply #1 on: 13 May 2003, 03:41 pm »
Nicely done, Larry.  It's refreshing to see your willingness to experiment and offer alternatives to your customers.  BTW, I had similiar experiences with the Mullard tubes in my old Sonic Frontiers SFL-1 preamp - not the most transparent with limited extension.

Beez

Psychicanimal

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12AT7 Tubes
« Reply #2 on: 14 May 2003, 03:29 am »
Have you guys tried cryogenic treatment of tubes at all?  It would be nice to hear what you guys have to say!

brad b

12AT7 Tubes
« Reply #3 on: 14 May 2003, 11:50 am »
interesting findings, as they are 180 degrees different than what I heard, although I haven't been able to hear as many different tubes as you have.  The difference may be that my REL takes over for the base, where I have heard the Mullard can get a little loose.

Mullard CV 4024 Cryo'd tubes had the smoothest high end, better depth of stage and silky midrange

Siemens tube pulled the soundstage closer, but lost a little of the midrange that the Mullard had.  This tube for me would be considered "neutral"

The stock tubes were very cool in the high end, and were a little tiring to me.

I also found for me that the biggest change ocurred in the preamp.  The amp tube change did not provide as much difference at the time.

Thank you for posting your thoughts.  Hopefully others will share their ideas, as you have a wonderful combo, and we all hear somewhat different, so I applaud you for trying other possibilities.
Brad

avahifi_lj

12AT7 Tubes
« Reply #4 on: 14 May 2003, 01:20 pm »
Hi:

Althought I didn't mention it in the original posting, the CV4024 is a cryo tube.


Larry


P.S.  I have been asked to create a unique login so you will see me under the avahifi_lj and Frank under avahifi....

avahifi_lj

12AT7 Tubes
« Reply #5 on: 14 May 2003, 01:32 pm »
Hi Brad:

Thanks for your input.  It is interesting hearing (pun intended) about the differences.

It's also interesting to hear your comments about the preamp verses the amp.  In our testing we noticed that as we got closer to the source (Transcendence DAC) the tubes had the same characteristics, but had more impact.

Thanks!

Larry Jenkins

Tyson

12AT7 Tubes
« Reply #6 on: 14 May 2003, 03:32 pm »
I pretty much agree with Brad.  I really like the Mullards in the preamp, but not in both the T7 and the 550ex.  With mullard in both, the sound (to me) is overly smooth and lacking in micro (and macro) dynamics, and the midbass is too prominent, with not enough deep bass.

But, with the Mullard in the T7 and the Siemens in the 550ex, it strikes a balance I really like.  And the soundstage is just perfect.  I am giving up a bit of extension and microdynamics compared to using Siemens in both the T7 and 550ex, but that combo sounds too forward to me.

50jess

  • Jr. Member
  • Posts: 99
Re: 12AT7 Tubes
« Reply #7 on: 8 Dec 2011, 01:41 am »
Nice review, Larry.  I found the RCA 12AT7 Black Plates to be the best among the Mullard 4024, Jan Phillips and Tungram that I have.  I give the EH a try.

Lefty052347

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  • Posts: 108
  • AVA Associate
Re: 12AT7 Tubes
« Reply #8 on: 8 Dec 2011, 02:24 am »
Just to let you know we are currently recommend/supply JJ ecc81s for our pre-amps requiring 12AT7s.  We also use JJ's in our FET Valve 400R and 600R amps.

Regards,
Dean

mark funk

Re: 12AT7 Tubes
« Reply #9 on: 9 Dec 2011, 10:56 pm »
I have tryed and own all the tubes in Larry's review. I didn't care for any of then (this is in a T-5 not T-7) and after a few years and a lot of money I think I have found what I like in a pair of tubes in my set. Most of the time I run Telefunken in all my stuff (T-5, T-DAC, Ultra+ 550). A few weeks ago I rolled a pair of NOS 1967 Valvo 6201 in my pre and although not as exstended in the high or low end as the Telefunken they have a real sweet midrange. Better then any Mullard I have or have heard and I have a pair of the real Mullards from 1955 made in the Mitcham works not the Blackburn plant. It seams I like the German tubes best.  :D


                                                                                    :smoke:

murf

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Re: 12AT7 Tubes
« Reply #10 on: 9 Dec 2011, 11:42 pm »
Great stuff Larry (& others),
    Since JJ's are stock in FetValves, how do you feel they compare to the other reviewed tubes?
  Can we look forward to more tube reviews?

Murf
« Last Edit: 26 Jan 2012, 09:58 pm by murf »

tonyptony

Re: 12AT7 Tubes
« Reply #11 on: 10 Dec 2011, 12:00 am »
I have tryed and own all the tubes in Larry's review. I didn't care for any of then (this is in a T-5 not T-7) and after a few years and a lot of money I think I have found what I like in a pair of tubes in my set. Most of the time I run Telefunken in all my stuff (T-5, T-DAC, Ultra+ 550). A few weeks ago I rolled a pair of NOS 1967 Valvo 6201 in my pre and although not as exstended in the high or low end as the Telefunken they have a real sweet midrange. Better then any Mullard I have or have heard and I have a pair of the real Mullards from 1955 made in the Mitcham works not the Blackburn plant. It seams I like the German tubes best.  :D


                                                                                    :smoke:

Mark, you're spot on. I have a pair of NOS Valvo Blue labels (very rare) and they do more magic in the midrange than the TFKs, without sounding toobey. I wish I had another pair. Having said that, the TFK 801S'es are no chopped liver.

Talking about in the FetValve of course.

ricmon

Re: 12AT7 Tubes
« Reply #12 on: 13 Dec 2011, 04:59 am »
Mark, you're spot on. I have a pair of NOS Valvo Blue labels (very rare) and they do more magic in the midrange than the TFKs, without sounding toobey. I wish I had another pair. Having said that, the TFK 801S'es are no chopped liver.

Talking about in the FetValve of course.

I've got to give my vote for the Telefunkin's as well.  Both line and phono section 801/803's.  It just don't get any better.

Ric

aln

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Re: 12AT7 Tubes
« Reply #13 on: 13 Dec 2011, 01:12 pm »
Any concerns about swapping out 12AT7 tubes in the new FET/Valve amplifier? 

tonyptony

Re: 12AT7 Tubes
« Reply #14 on: 13 Dec 2011, 05:09 pm »
I suspect Frank will chime in here, but with the new 400R / 600R Frank cautioned me to be very careful when swapping out tubes. There is a very high voltage present on the left hand side fins which are very near to where your hand would be for swapping out the left tube. I'll let Frank provide the details, but at a minimum one should wait several minutes before lifting the cover off for a swap. I'm making no claim that this is all you'd have to watch out for.

If the concern is about rebiasing, I'll leave that for Frank as well. :)

avahifi

Re: 12AT7 Tubes
« Reply #15 on: 13 Dec 2011, 10:13 pm »
Tony is correct, the heat fins at the top of the regulated power supply board (vertical board, in front of the audio boards that contain the tubes) do hold a high voltage charge for some time (at least an hour or two even with the bleed down resistors installed).  You certainly won't like the feel of having your hand bump into these fins while trying to swap out tubes.  You will probably only do this once.  :o

Regarding bias setting, we have found that all good working customer supplied tubes have biased up well within the normal range for the amplifier, so I am comfortable with you swapping tubes without attempting to reset bias (which is a difficult and hazardous job if you don't know exactly what you are doing).

Regards,

Frank Van Alstine

mark funk

Re: 12AT7 Tubes
« Reply #16 on: 13 Dec 2011, 10:49 pm »
Tony,
      Ya the Valvo has that midrange every one is listening for but the TFK well be back in soon. Valvo just does not have the low end or high end of the TFK in my set and that is a lot too give up, bass! I have three pair of the Valvo. One pair from 1955 and two pair from mid 60s, no blue ones. I though we talked about that before?

                                                                                              :smoke:

tonyptony

Re: 12AT7 Tubes
« Reply #17 on: 14 Dec 2011, 12:12 am »
I though we talked about that before?

Yes, I think we did, but at that time I hadn't really tried the Valvo Blues for any serious length of time. I will agree they are a little softer in the low end, but the more I listened to them the more I felt like I could live with them happily. I did put the TFKs back in, though. :D

mark funk

Re: 12AT7 Tubes
« Reply #18 on: 14 Dec 2011, 01:10 am »
I took some pics of some tubes but the only one you can read is this one, I well try again.





                                                                                      :smoke:

tonyptony

Re: 12AT7 Tubes
« Reply #19 on: 14 Dec 2011, 02:53 am »
Sweet. I have many of the same and a few others (Sylvania GBs, Siemens triple micas, RCA black plates).