Recommend me a warm, smooth sounding 6922, 6DJ8, ECC88 or equivalent

[gaplessophile]

I've just built a tube-buffered chip amp, and need to buy a new 6922 or equivalent to use in it. The design I followed is here http://www.customanalogue.com/diytub...lone/index.htm .

I'll be buying off eBay - I live in New Zealand, and this seems to be the best way to get a wide range of tubes.

I'd like to get one that sounds nice and warm and smooth, if possible.

Are there any particular brands or types that would suit me best?

If anyone has any opinions on whether the design I chose was a good choice when my goal is warm, smooth sound, I'd be interested to know this too.

Thanks heaps

[Gordy]

Originally posted by gaplessophile
I've just built a tube-buffered chip amp, and need to buy a new 6922 or equivalent to use in it.
...
I'd like to get one that sounds nice and warm and smooth... .

At the risk of offending you (and any other sentiment-driven lurkers) I will tell you the truth: a vacuum tube does not have a sound quality, and hence you can not seek one that has a "nice and warm and smooth" sound.

Instead they have electrical characteristics that the designer selects and must manipulate by way of the surrounding circuitry in order to influence the overall sound quality of the system.

The notion that there are tubes which sound warm, or harsh, or accurate, or smooth, etc., is just nonsense spoken by people who want to sound as if they understand the subject, or who want to be seen as experts to boost their own ego, or they want to sell you something.

The tube in the linked schematic is an impedance converter - it presents a high impedance at the input so as to not load down the source, and creates a low(-ish) impedance at its output to drive the chipamp. I am surprised that the chipamp needs this impedance converter ( / buffer). The tube in this configuration will reduce the size of the input signal a little (which is a fact, but it may not be important), and it will introduce a little distortion. You may in fact like that type of distortion or you may not even notice it.

If you are very lucky the tube specification and the opperating point set by the designer (via the surrounding components) may contribute towards a sound that you interpret as 'warm and smooth'. Let's hope so.

[HollowState]

What Grody said! And I could not have said it better myself. I have always believed that a tube has no characteristic sound of it's own, so long as it was "good" and not too microphonic or noisy. Why would a stream of electrons in one tube sound different from another? Seems logical, yes? But there's one small problem.

I'm not a hyper-sensitive listener (thank God) like some people I know from the NJ Audio Society I belong to. But even in my mid 60's I can detect subtle differences between certain like number tubes. Almost always small signal and preamp stages. I don't know exactly why this is, but I can hear it. Maybe it's psycho-acoustical or metaphysical to some extent. But it's there. I think this is what gaplessophile is refering to. The fact that in a given fixed circuit different tubes, of the same type, may sound slightly different.

There is no definitive way to predict what tubes will sound good to your personal ear/brain system. I would suggest to gaplessophile that he obtain an assortment to experiment with. I know this is not what he wanted, but there is no correct answer. Only rough guide lines based on one's personal taste. So I'll give you mine.

I prefer European NOS like Amperex, Mullard, Siemens and Telefunken to name a few. The Amperex "Premium Quality" 7308 w/gold pins is one of my favorites. Also, American Sylvania "gold brand" and GE "five star" are premium grades built for low noise. I have no experience with Chinese or Russian tubes. Don't need them, don't want them and don't like them for various reasons. But they are cheap and plentiful so you might want to try some if you can live with their faults. (miss-matched sections & OOT specs.)

[rknize]

While I agree with the core of what Gordy and HS are saying, I think that is a great oversimplification and maybe not too clear to the original poster? How the characteristics of a brand and type of tube sound is, as you stated, completely dependent on the circuit in question.

As Gordy stated, in that circuit the tube has no gain and so will introduce little if any of the even-order distortion you might be after. I also don't see the point of using a tube there other than for the sake of having a tube somewhere.

[Wavebourn]

Load it on SVCS if you want to find the best sweet spot for any tube; then vary plate voltage and cathode resistance in order to find it. It is usually wide enough allowing a huge swing of an output signal.

Any tube has it, but some on very low currents, some on very high currents, but some don't have it because it would be needed to bias it's grid positively, also some need too high voltage for their sweet spot so it is not practical.

All 6922, 6DJ8, ECC88, 6N23P and others has sweet spots on approximately the same voltages and currents.

However, if you want to swap the tube in some particular design you have to guess what tubes better fit in conditions predefined by the developer that most usually used databooks and datasheets for particular tubes. No one can help you there.

For the design on the link also nobody can help you because 100% feedback in cathode follower eliminates all differences. Probably, the right answer is, "Buy a healthy one"

[panos29]

You only need to try one tube !

6N23P-EV

Just my 2 cents...

[gaplessophile]

Many thanks for all your responses!

Please forgive my lack of knowledge about tubes - your advice has hopefully set me on track

That's interesting that the tube needs to be providing some sort of voltage gain in order to "colour" the sound much - maybe I didn't pick the most appropriate design after all.

I guess I'll just get a tube and find out

[Majestic]

Hi gaplessophile,

In terms of modern production (ie easiest for you to obtain) it's not looking too bad. The current JJ brand was surprisingly pleasant to my ears. Even the Sovtek 6922 isn't too harsh (although it's rather mind-numbingly boring and 'oppressive' sounding for music playback). There are new entrants all the time and there may now be something out now that's better than the JJ, but I can't say since havn't had any cause to seek out a replacement set yet

As for the makes of yore: Mullard, Amperex, and Philips 'SQ' have tended to be my own preferences matching the kind of sonics you seek. Siemens (also rebranded by RCA) tend to be a little more extended in the highs, but still manage a pretty liquid & grain-free presentation.
Any of the aforementioned would tend to cost 3 to 4 times more $'s than a JJ, however.

[Shoog]

Something to be aware of, the 6922 family is quite prone to instability - which will manifest as harsh brittle sound. So very careful attention to layout with grid stoppers and the anode load right on the pin, will eliminate this as an issue.

I built that circuit a long time ago- watch for large amounts of DC on the output at power up (I fried some vintage speakers with this buffer). Also be aware that this is a very much simplified version of the commercial version offered elsewhere on the sight, and the sound quality to be expected is not what is possible.

Shoog

[Gordy]

Originally posted by Gordy


At the risk of offending you (and any other sentiment-driven lurkers) I will tell you the truth: a vacuum tube does not have a sound quality, and hence you can not seek one that has a "nice and warm and smooth" sound.

Instead they have electrical characteristics that the designer selects and must manipulate by way of the surrounding circuitry in order to influence the overall sound quality of the system.

The notion that there are tubes which sound warm, or harsh, or accurate, or smooth, etc., is just nonsense spoken by people who want to sound as if they understand the subject, or who want to be seen as experts to boost their own ego, or they want to sell you something.

Originally posted by Majestic

...
In terms of modern production (ie easiest for you to obtain) it's not looking too bad. The current JJ brand was surprisingly pleasant to my ears. Even the Sovtek 6922 isn't too harsh (although it's rather mind-numbingly boring and 'oppressive' sounding for music playback).
...
As for the makes of yore: Mullard, Amperex, and Philips 'SQ' have tended to be my own preferences matching the kind of sonics you seek. Siemens (also rebranded by RCA) tend to be a little more extended in the highs, but still manage a pretty liquid & grain-free presentation.
...

EXCUSE ME. WHICH PART OF... "a vacuum tube does not have a sound quality... Instead they have electrical characteristics that the designer selects and must manipulate by way of the surrounding circuitry in order to influence the overall sound quality of the system." ...DID YOU NOT UNDERSTAND?

I offer you a FACT, yet you still insist on some namby-pamby, sentiment-driven, emotional drama-queen audiophile nonsense?

May I suggest AudioAsylum.com for your emotional needs.

And while I have your attention let me give you a couple of hints:

1.
JJ, Mullard, Philips, etc., produced hundreds of thousands of each type of tube. For you, or any 'audiophile', to draw a conclusion from sampling only a few (or maybe just a pair) from such a vast number is complete nonsense.

2.
There is one main specification for each tube, and everything else you hear (...in an otherwise equivalent circuit ...) is down to TOLERANCES. Some were pretty decent at 10%, while others exceeded 20% or more. That is the difference you are hearing... the tolerances between each individual tube interacting with the circuit... not the difference between manufacturers.


So why the pseudo-rant? Because you have taken a sample of so few from a sea of so many and drawn a sentiment-based conclusion and then offer it as if it is a fact. This is the sort of nonsense that BLIGHTS audio design and promotes further misinformation as non-technical drivel is spread from person to person.

OK, rant done.
Said Gordy, shaking his head, as he wandered off to the pub...