[Quiet Earth]

Here you go : http://www.audionote.co.uk/products/digital/dac_3.1x_bal_01.shtml

But we are getting a little off topic now...... Have fun!

[JoshK]

Here you go : http://www.audionote.co.uk/products/digital/dac_3.1x_bal_01.shtml

But we are getting a little off topic now...... Have fun!

Ah...I thought you might be an AN fanboy....I have no love nor hate for them.  Just think they are overpriced is all.

They are using 12AU7s in CF which is a world of difference than using them for gain.   They are using the 6DJ8 for gain (which is linear).  Apples vs Oranges in this case.

[Quiet Earth]

There is no 6dj8 in my dac.

The 12au7 in my dac is used for gain, how else would I hear what's coming off the dac chip and step up transformer?.. How/ why would I step down if I did not develop so much gain? Why did you call me a fanboy?

It's a moot point and going way OT. I don't think this is going to go anywhere constructive.

[JoshK]

what you linked was the DAC 3.1 which is said to use the 6DJ8 in gain to a 12au7 in CF unless I misunderstood something...   yeah off topic, but sometimes off topics are fruitful as long as they are civil.   Cheers!

[JoshK]

Ahh I was wrong...to quick to read...

") Improved line amplifier circuit, we have moved from the use of 2 x 6DJ8/ECC88 run in parallel to a series stage consisting of two ECC82s, this allowed the use of a better output transformer"

I read that with the glasses of prior knowledge of their design.    I take the series stage to mean gain into CF though.   In which case, they might very well be doing something like Broskie does in the Aikido to get very good performance out of the 12AU7, but using the non-linearity of the 12au7 to cancel the non-linearity of the 12aut7, hence the aikido affect. 

[Quiet Earth]

As long as you're happy.

[JoshK]

I am still not convinced they are...but I will plead ignorance.    I still stand by the fact that 12AU7 is very non-linear.   I would choose just about any triode over it.   I can't think of a single circuit that would benefit from its inclusion.

[Quiet Earth]

You sound like you know what you are talking about. You have certainly heard more 12au7s than me, and you know more of the circuits by name. However,,,,

I don't think I am imagining things when I say that my DAC sounds really good. I think this is a good example of not being able to judge what a tube sounds like based on the number on it. It's what you do with it that counts.

Cheers! 

[medium jim]

Well I have heard many 12AU7 circuits and have yet to like a single one.   I know there are super clever designers like Morgan Jones, John Broskie and Anatoliy who could design something brilliant with them but typically choose not to for reasons I stated above.  If you list your particular piece of gear we can see if we can find the particular implementation so we are not talking in generalities.

I guess you haven't heard the Bottlehead Foreplay III Preamp that utilizes 12AU7's....

Jim

[JoshK]

No, I haven't heard that one....I respect their design skills....  I know they use a  CCS to linearize the tube's effect.   Which work good with just about any tube.   I have since grown to like prefer a gyrator over a CCS at least philosophically, based on what it does with HD.   I haven't built a comparison to test with my own ears, so I won't make big statements here.   Bottlehead does good stuff, even if they chooose the lowly 12au7. 

[medium jim]

No, I haven't heard that one....I respect their design skills....  I know they use a  CCS to linearize the tube's effect.   Which work good with just about any tube.   I have since grown to like prefer a gyrator over a CCS at least philosophically, based on what it does with HD.   I haven't built a comparison to test with my own ears, so I won't make big statements here.   Bottlehead does good stuff, even if they chooose the lowly 12au7. 

Mine has been modded for a 6FQ7 which is about the same gain factor, but much more detailed and spacious.   I asked Doc why he doesn't use the same and he went off a little bit, but did say he tried it and it was very similar to the presentation the 12AU7 gives...I think it was because the 6FQ7 while readily available is more expensive than the 12AU7...there mantra is beer budget audiophile....

However, I must agree with Doc, his design likes the 12AU7...very linear and musical. 

Jim

[cheap-Jack]

HI.

...not being able to judge what a tube sounds like based on the number on it. It's what you do with it that counts.Cheers! 

Yes, you've said it.

Many DIYers hate 12AX7 sound & refer using 6DJ8, etc etc of the same family instead.
But given proper design-built, my phonostages, all using 50-year-young vintage Telefunken ECC83s, sound superb - fast, transparent,
punchy, yet musical. No vintage sounding at all.

Design-build it right, it will sound good.

c-J

[JakeJ]

I'm with Quiet Earth & c-J on this.  I would pay good money, maybe even as much as...oh...$20 if JoshK could hear my VAC CPA-1, that utilizes 12AU7's in the linestage and the phono section uses four 12AX7's with a pair of 6DJ8's switched in for MC duty.  I've had more than one audio buddy (including pro reviewers) tell me I'd have to spend considerable bucks to exceed the performance of the VAC.

I am very happy with my main rig at this time.

We now continue with your regularly scheduled program.  ( OT)

[SET Man]

Hey!

    Geeez.... how sad is this? This thread started out very nicely by the original poster SteveFord. My pre use four 12AX7s in the phono stage and my second amp use four also. So, with that I was very interested but than this thread turn in to a technical pissing contest between 12AX7 vs 12AU7 and other types of tube. 

    Well, the thread say 12AX7... so let's keep the discussion on the "sound" of this type (and it's equivalent) would ya? Or just start a new thread 12AX7 vs 12AU7 vs whatever. Thanks.

Take care,
Buddy

[Ericus Rex]

Well said, Buddy!   

[SET Man]

Well said, Buddy!   

Hey!

   No, problem. Since 12AX7 tube is a very popular tube this thread can be very useful to many people here.

   So, how about getting back to the sound of the varieties of 12AX7 tubes out there?

Take care,
Buddy

[SET Man]

Hey!

   OK, let's see.

    Currently I have Ei Gold Elite 12AX7s in my Audio Note M1's phono stage section. They are nearly 10 years old now and they still test well and sound good. Unfortunately they are no longer made so. It won't be long 'til I have to replace them so it will be nice to know how other 12AX7 tubes out there are like.

    Other 12AX7 I have right now are Ei 12AX7 the "Silver Bullet" one late production. I haven't try them yet but they don't measure that well on my Hickok 6000 tube tester. I also have 4 Mullard CV4004 in my second amp that I recently picked up. They sound wonderful in that amp but I haven't compare them to the Ei tubes I have.

     Anyway, I have to say that I'm more interested in new production 12AX7 tubes than NOS because good NOS are getting pricey these days. Feedback from new production tubes will be very useful.  Unless you know some NOS 12AX7 type that still reasonable priced.

    I see that the original poster SteveFord mentioned that he like the JJ ECC803S. I've been eying this for a while now since the price is very good. I might check them out. BTW... had anyone here tried the new Genalex Gold Lion 12AX7 yet?

Take care,
Buddy

[mjosef]

Buddy, I tried the new GL 12AX7 vs. the new TungSol vs. the new Mullard vs the Sovtek LPS...of the bunch I liked the TS the best. The Mullard sounded 'fuzzy' compared to the TS, the GL sounded 'heavy' in the lower freq. which resulted in a 'thumpy' sound. The LPS is on the lean side.
The TS had the best balance across the freqs. with a great 3D soundstage. All the tubes were cryoed except the Mullard. Results obtained in my CAT pre line stage.
I found the results matched those in the pre line stage when tried in my Jolida amp.

In the phono stage I use the LPS, but since I rarely play vinyl, did not experiment with all the tubes in that position. I can always bring them over for you to try in your AN.

[Ericus Rex]

Here's some interesting info.  Just keep in mind this is a guitar amp site.


http://www.tubesandmore.com/tech_corner/12ax7_comparison_of_current_made_tubes

[avahifi]

Keep in mind that the gain of a given tube will have a significant musical effect in a typical audio circuit with gain and having overall loop feedback.

In such a circuit the overall closed loop gain of the circuit is set by the feedback loop. To simplify, the amount of feedback will be the difference between the open loop gain of the tube used and the closed loop gain of the circuit.

Thus, in this typical circuit, the amount of feedback will be essentially set by the open loop gain of the tube selected.  A high gain tube will provide higher feedback, a low gain tube less feedback.

In general, low feedback tends to produce a more mellow, less aggressive sound, if done well, a very pleasant overall presentation.  However lower feedback means higher harmonic distortion, and poorer control of the wanted audio signal.  Not enough feedback results in mud, boomy bass, and poor transparency.

At the other extreme, a very high gain tube used in a typical line circuit will provide higher feedback.  This results in more clarity and transparency, but too much feedback can produce a very grainy, hot, bright, and fatiguing musical presentation, likely from transient intermodulation distortion as the excess feedback overloads the loop.

In general, you need to know a bit about the circuit design in trying to select appropriate tube for it.  What is a great high gain tube in one circuit may overload a different one.  A nice musical low gain tube in one circuit, may sound like mud in a different application.

There is more than magic involved with tube selection (although some of it still seems to have some magic aspects).

To sum up, the great sounding tube in one circuit can easily be a terrible sounding one in a different one and some of these issues can be reduced if you know what tube gain your circuit would actually like to see.

Regards,

Frank Van Alstine