Tube ? from a tube dumbass

dragon1952

Yes, I am a tube dumbass

I've done a little browsing around though so let me see if I've got this straight. When you say the Dodd ELP uses 6DJ8/6922 tubes, the 6DJ8 and 6922's are two separate but compatible tubes and you can use either a pair of the 6DJ8's or a pair of the 6922's? I'm assuming they have the same electrical properties but is there any difference between the two sonically? And how big of a difference does it really make if you get matched and balanced triodes? Is it just a feel good tweakie kind of thing or what?
Thanks and if I've got it all f#&ked up please don't ridicule me too much....I happen to be very sensitive :rolleyes:

BlueMDPicker

Actually, you could use one of each without issue.

Matching tubes is somewhat critical if two, or more, tubes are used in the gain or output stage.

In twin triodes, balancing is desirable between the tube sections.

In a 2-tube pre where one of the tubes is a phase splitter, the other gain, matching is not critical. In fact, you can tailor the sound to quite a degree by using non-matched pairs.

Hope that helps.

Mike

dragon1952

Yes it does....thank you very much!

I've also seen some references to 7308/E188CC's. Are these a suitable replacement for the 6DJ8/6922's?

BlueMDPicker

Here's a link that will give you some background. Don't pay too much attention to Joe's opinions. Tube rolling is a very subjective "science" that is dependent on the actual gear the tube operates in:
Joe's Tube Lore 6DJ8/6922/7308

dragon1952

LOL! Thanks! I like what he has to say about the Sovteks that are coming with the ELP Actually though, I've run across a couple of opinions so far that they're really not too shabby.

RuSsMaN

All a 6922 is, is a mil-spec (met high specifications for military use) 6DJ8. It is the same exact tube.

All you need to do, is start rolling. If you need something, let me know.

Cheers,
Russ

dragon1952

Cool....thanks man. I appreciate it.
BTW, what is your opinion of the Amperex 6DJ8 orange globe logo I think it's called.
If they test over 100 are they a good value at around $60 a pair?
And/or.....do you have anything that would be a decent upgrade to the Sovteks that I might be interested in? Not that I feel I'll be unhappy with them but it would be cool to see the differences rolling can make right off the bat.
From what I've read I guess the choice of tubes can be system dependant also. I'll be using the Conrad Johnson Sonographe SA-250 with the ELP and a NAD C541i CDP and the Studio 40's. BTW the Sonographe is working nicely in my system so far. It's tamed some of the brightness of the NAD and Paradigms.
Thanks again

BlueMDPicker

Just a suggestion but, if you're new to tube rolling, grab some cheaper tubes to play with. The EH gold pin 6922 sound pretty darn good in about everything I've had them in - under $15 each. The JAN Phillips 6922 is excellent, usually in the same price range. And, I like the sound of Ei Elite 6922s - although some can be microphonic - they can be had often for <$10. Used, '50 and '60s RCA black plates can be found sometimes for <$10 and are excellent (you may have to go through a few used ones to weed out noisey ones.)

"Tested" tubes are usually just an indication of their expected life. Most tube sellers will not vouch for how noisey or microphonic the tube is, just that it "tests good/new." Look at the internal build of the tube you're interested in. Well built tubes usually sound the best (hence the popularity of the JAN tubes.) I personally like the sound of 6922/6DJ8s with halo or square D getters. You'll develop your own preferences with experience. Have fun!

dragon1952

Thanks....I was going to pick up the JAN Phillips. I've seen them several places. I'm going to splurge a little too though and spend about $60 for a pair of bugle boys or the orange globe logos. There's a guy on Audiogon with great feedback (no pun intended) who not only tests them with a tester, but he puts them in his own system and tests for microphonics.
Appreciate the advice

faster100

Dragon, Ive bought a pair of jan phillips 6922's and they were terribly microphonic, However i just got a set of jan sylvania 6dj8's and they were used and sound great and totally quiet.. I also picked up a pair of bugle boy amperex 6dj8's and got them for under 30 bucks tested out like new.. seems maybe this tube model numbers show more noise or something, because i never had a noisey tube with my other pre with the 12ax7's

organ

One thing to keep in mind. A circuit designed ONLY for 6922 will eat 6DJ8's for breakfast. 6922 have a slightly higher heater voltage. To my ears, 6DJ8's are more 'colored' and warmer sounding.

Maurice

BlueMDPicker

Hi Maurice,

Not to put too fine a point on this, but both tubes have 6.3V heaters. The 6922 has a much higher (nearly double) maximum plate voltage, undoubtedly to meet mil spec. However, in Class A application, both tubes operate within 10% of each other with respect to operational plate voltage. This is not to say that there isn't some audio gear out there that was "designed for" 6922s -- but IMO nothing measurable in the way of transconductance between the triode sections, amplification factor, and plate dissipation would be achieved by operating the tube at plate voltages higher than the 6DJ8s max.

Mike

organ

Thanks for the correction, Mike. For some reason I thought it was the heater voltage. I read about this issue on audioasylum. Some people that didn't know about it lost their 6DJ8's really fast.

Maurice