[tanchiro58]

As always, it's horses for courses. I suppose if you have high sensitivity speakers, they'll be more prone to portray any microphonics from the tubes. But, where do the microphonics come from - the tubes do not create them. Have you tried dampers and the like?

MarkC,

I have the same opinion since my speakers are horn-loaded speakers (alnico magnet type). I thought the microphonics caused by the SET amp but after I switched to Altmann BYOB amp (10w output) I can clearly hear more microphonics that are annoying me. However, I also tried 7308 tubes which have less microphonics and more musical than 6922s. Somehow there could be the problems of the design of Promitheus Apollo preamp that I am not be able to solve or modify.

Tan

[Freo-1]

I absolutely agree with Brown & Steve. Different tubes in different circuits will sound..well..different.
I'm just starting on the 6DJ8/6922 journey with a recently acquired DAC. As with all of my previous experiences, N.O.S tubes are the better performers so far. One exception to this is the 6N1P.
I've tried 3 different types  with the DAC so far and they are: Sovtek - stock, Philips JAN 6922 and Philips N.O.S SQ 6922 from the '60's.
My evaluation in my equipment is: Sovtek - O.K bass, subdued mids and restricted highs. Overall a pretty dark sound in my mostly tube kit.
Philips JAN 6922 - Same bass as above, better mids and highs - definitely an improvement for not a lot of $.
N.O.S Philips SQ 6922 - HUGE improvement across the board. Better, more solid bass, more liquid mids ,  extended highs. But - MUCH more $.
I just received a pair of Amperex orange world logo 6DJ8's, and will be giving them a go.
Problem is; when you switch coupling caps or even cables, it's a whole new experiment.

It really is "horses for courses" It's virtually impossible to come up with one "best". Even within a given type, they sound different. for example, the US 6922 has a slightly different sonic signature to the dutch made ones. When they were made also plays into this. I have two sets of 6922 from Phillips Holland, one from 62, and the other from 69. They are slightly different sounding.

In my experience, the Siemans 6922 from the late 60's is the cleanest set I've heard in my system. However, the most seductive sound is actually a set of 6DJ8 from Holland labeled Rogers, with a date of 64. I also have a set of NOS Amperex 6DJ8 from 58 with D getters that sound incredible.

There are some very basic generalities with a given type of 6DJ8 types, but there is just too much variance to declare any one a clear overall winner.

As astutely pointed out, the overall system synergy plays into the sonic signature.

[JoshK]

But, where do the microphonics come from - the tubes do not create them. Have you tried dampers and the like?

I am no expert on the topic, but my understanding is that the tube is picking up external vibrations.  Microphonic tubes are basically resonating from the external vibration and this resonance, a bell like effect, is being amplified.   If the tubes are placed inside a chassis shielded from air vibration then they won't amplify this effect.  If you further take measures to isolate the tube socket from chassis born vibrations you can do further. 

[markC]

I've had the 6DJ8's in the circuit for a while now and damned if I don't prefer them over the Philips SQ's. Bass is ever so slightly less, mid's pretty much identical , but highs are more delicate and seductive.
At about half the price of the Philips 6922, I'll take the Amperex 6DJ8. I'll be ordering a back-up pair as I suspect the more expensive these tubes get, the less they will be obtainable by enthusiasts such as myself.

[dorokusai]

It's a toss up between Mullard and Amperex White for me. There was a time when JAN series were the rage but a bunch of them were microphonic out of the box. I used them in a Dod pre-amp with great success, not so much elsewhere.

Mark

[jules]

. I also have a set of NOS Amperex 6DJ8 from 58 with D getters that sound incredible.

yes Freo, I agree with that one! The Amperex 6DJ8 '58 D getter doesn't get all the attention that other D getters from the same period do but it's one of my favourite tubes. It's fantastic for vocals and manages to be detailed and warm at the same ... pity they're nearly extinct.

I've had the 6DJ8's in the circuit for a while now and damned if I don't prefer them over the Philips SQ's.

yes again ... In the early 70's Amperex/Philips/Mullard and Siemens tried out A frame construction for a few years before descending into some rather nasty single O getter tubes. I have the feeling that it's largely fashion that dictates that the only good tubes are 50's to mid '60s though there could be other good reasons why people became wary. Several previously high quality manufacturers allowed their name to be used on sub-standard tubes that were produced under licence.

The type of tube doesn't seem to have all that much bearing on their being good or bad. Valvo E88CC gold pin valves should be good but sound horrible to me and I felt the same way about Amperex green USA [though for different reasons]. On the other hand a couple of my fav. tubes are 6DJ8s ... Siemens grey plate, double getter, '63 and the Amperex '58 D getter.

Can I add to what Josh has said with the same proviso that "I am no expert on the topic" ... As well as being caused by external influences it seems that a heavy load on a tube can set up vibrations. In  addition, one way of making a tube microphonic is apparently to knock it while it's hot. This suggests to me that what happens is that the heater filament stretches when it's red hot [and soft]. As I said a couple of pages back though, microphonics don't always happen with particular tubes. I've been trying out a heap of 6DJ8/6992s over the last few months and I haven't had any trouble with microphonics in any of them [in an AKSA GK-1 pre-amp with mininal gain and the heater voltage deliberately set lower than the specified value].

jules

[jaywills]

You might want to consider trying a 7DJ8/PCC88 pinched waist d-getter (steel pin) from the mid-to-late '50's.  They're still reasonably priced and compare well to the 6922 pinched waist d-getters (gold pin) in my Melos preamp (just don't mix the 7dj8's with the 6922's).  Of course, YMMV.  Cordially,

[Midnite Mick]

Since I tried the PCC88 tubes in my amps I have been experiencing hissing noise out of my tweeters.  Apparently, they are not always a drop in....I am going to test some of the tubes but I fear I may have to send my amps in now.

[tanchiro58]

I have tried and used Siemens PCC189 in my Promitheus Apollo preamp and got "dead quiet" with no buzz and no microphonics. Siemens PCC189/7ES8 is cheap ($10-15) and sounds excellent too. 

[Midnite Mick]

I had Tungsram and was very impressed with how quiet they were as well.  The noise came after a period of time.  I am assuming that this is the cause but like I said I still have to do some testing on other tubes as well.  It is just that they are monoblocks and it would be odd for both of them to develop the problem on their own without some common cause.

Thanks,
Mike

[markC]

If I were to try a different tube than the orange globe Amperex 6dj8, what would you recommend?  Late '60's white label "A" frame Amperex or late "60's Bugle Boy.

[jules]

Mark,

There's two general directions you can try ...

You can try Siemens/Telefunken tubes for precision and accuracy. My own view is that they need a really good system to shine but that's not a reflection on anything lacking in the tubes.

or

You can try some of the more colored tubes like the above mentioned Amperex '58 D getters. You could also try Mullards which have a reputation for being warm in an english kind of way.

A good way to experiment is to buy good but used tubes of slightly less popular types on ebay. A PCC88 Telefunken, for example, sells for half the price of an E88CC. If you can pick up some early gray plate double getter ECC88 Siemens, they are well worth a listen.

If you want to play round with different sounds, the white label A frames probably aren't going to be all that different to your orange globe labels [I presumed they were A frame but they could have been double getter].

JJ Tesla apparently sound a bit like Telefunkens but can be unreliable.

Philips/Amperex miniwatt PQ are hugely expensive but you might be able to pick up a Dario or other french labelled valve. Dario are french made Philips.

There's been a few suggestions above to try 6ES8s. If you're into vinyl this might be a good move. The bugle boy 6es8 is an interesting tube with a good reputation for valve phono-stages and headphone amps. The Telefunken ECC189 has a similar reputation but is very hard to find these days. I don't like 6ES8s in my system because they can give a sort of fractured edge to sounds, particularly vocals though I've found them to be ok with re-mastered analogue to digital work [a narrow and fairly horrible medium for the most part  ].

jules

[markC]

Thanks for your input Jules.
I do suspect that the tubes I mentioned will sound similar to the orange globes, (they are not "A" frame btw). I wish there was a way to audition N.O.S tubes!
I like the sound the orange's present; just wondering if a little more refined sound could be had by going with a similar, more "factory screened" version.

[jules]

I wish there was a way to audition N.O.S tubes!

Oh yes ... I'd love to hear a set of pinched waist, D getter Amperex tubes from the late 50's without having to pay $700 for them.

I don't know of a way to find more "factory screened" tubes aside from CCa. Even with these, the specs are the same [observation based on Telefunken spec sheets] as the specs for E88CC. The CCa is apparently selected as being in the top 10% on a low noise basis but I'm slightly skeptical of how important this is. The standard was developed for telephone communications not audio. You might find a difference between the Dutch version of a tube, the US version of the tube or maybe the english version of the same tube but it's probably better to try something completely different.

If you're after detail, Siemens or Telefunken are the obvious choice. Don't buy any Tele's later than 1970 and don't buy any Siemens later than 1970 unless they happen to be A frames.

After a whole lot of testing with cheapish tubes I took the plunge and bought some  '68 E88CC telefunkens. They are now my standard for accuracy but there's other tubes out there that are great listening for slightly different reasons. In  way, it's like changing your speakers without having to spend a few thousand dollars 

jules