Tube orientation in Premier 17

[Puma Cat]

Hey C-J gang,

My local dealer lent me four NOS 6922 type tubes to try out in my Premier 17. Only catch is that two of them are Amperex and two are RCA, so I don't have four of the same type. The Premier is somewhat unusual in that it is a composite triode, but I dont know the order of the tubes with respect to channel. The four tube sockets are all in a line, from front to back. What I don't know is whether the first two tubes are one channel, the other two are the other channel, or, if the first and second sockets are the first tube for the L/R channels, respectivley, and then the third and fourth sockets are the second tube for the L/R channel, rspesctively.

Anyone know which tubes are for which channel? I don't believe I have a schematic in my owners manual.

[Joe Appierto]

I may be reading this quote from Lew Johnson in a Sam Tellig review of the Premier 17 LS2 incorrectly, but it sounds to me like each 6922 is used for both channels. Here is the quote:

"We created a super triode—or a composite triode—by paralleling multiple triodes from the four Sovtek 6922 tubes. Each of the tubes is a twin triode. Four triodes are paralleled for the left channel and four triodes are paralleled for the right. They are put together in parallel to make one big triode. In effect, you have a single triode per channel."

If I understand what he's saying correctly, the (let's say) left triode of each tube is paralleled and comprises the left channel and similarly the right triode of each 6922 is paralleled for the right channel. So, it shouldn't make a difference in what order you insert the tubes.

When I had a Premier 17 LS and played mix and match, I'd alternate the tubes and each channel sounded the same to me. It would appear from the article that wasn't necessary but maybe it wouldn't hurt anyway.

Here's the original review:

Conrad-Johnson Premier 17LS line-stage preamplifier | Stereophile.com (http://www.stereophile.com/tubepreamps/370/index.html)

Hope this helps.

[Rafale]

Joe is right, each 6922 for each channel
from the HI-FI news review by M Colloms September 2000 :
The active part consists of four paralleled triodes per channel, run at zero feedback with fixed bias, anode-coupled at the outpout and relay-muted

[Puma Cat]

Okay, guys, thanks, I thought that might be the case as these were twin triodes...they are stacking 4 x 1 triode section for each channel in parallel to acheive a lower output impedance. This is what the ART did, and it and the Pr16 acheieved even lower output impedances because they used more tubes in the composite triode design, 10 and 6, respectively.

So, it doesn't matter what what I do in the long run then, so I think I will alternate Amperex with RCA per Joe's comments. My dealer that lent me the tubes likes mixing and matching different tubes in a given circuit to get just the right mix, so we'll see how it turns out.

Talk about your mixing and matching! :D

[Rayooo]

so if you mix mullard and telefunken per channel is it then a mullafunken? ok, sorry.

[Puma Cat]

Yes, it's a Mullafunken! I like, I like!

I'm going to have an RCAmperex here in a few minutes!

Or, is that AmpeRCA?

All depends which tube goes in socket 1 first.

Fun with tubes!

LOL!

:D

[Puma Cat]

Well, I just put 'em in....turns out the other set were a set of cryo'd NOS GE, not RCA, so I've got Gemperex tubes....

As these are NOS, these will need some burn in, but first impressions are....

:drool:
:music:

Will post pix of the way cool GE boxes shortly...

The Amperexes are from 1969, BTW. The GEs look older than that...50's, probably.

[Joe Appierto]

Just one comment, if you don't mind. The tubes you're using are all 6922s. I've heard of some more adventurous souls who mix types (e.g., a couple of 6922s and a couple of 7308s) and do not report any problems doing so. However, once you mix types then you're mixing different electrical characteristics and I might just be overly cautious, but that may not be the best route to take.

Not implying that you'd do that but I did want to put that out there.

[Puma Cat]

Just one comment, if you don't mind. The tubes you're using are all 6922s. I've heard of some more adventurous souls who mix types (e.g., a couple of 6922s and a couple of 7308s) and do not report any problems doing so. However, once you mix types then you're mixing different electrical characteristics and I might just be overly cautious, but that may not be the best route to take.

Not implying that you'd do that but I did want to put that out there.

Thanks, Joe, appreciate the caveat.

The tubes I'm using are all 6922s...they should have identical electrical, but different sonic characateristics.

So far, so good...

[ronenash]

Joe is right, each 6922 for each channel
from the HI-FI news review by M Colloms September 2000 :
The active part consists of four paralleled triodes per channel, run at zero feedback with fixed bias, anode-coupled at the outpout and relay-muted

I am almost sure this is not the case. Four parallel triods can be achieved by paralleling the 4 sections of two tubes. If I remember correctly this is how CJ does it to avoid crosstalk between the channels. Channel seperation will be much better when using seperate tubes for each channel. Also noise does not pass from one channel to the other when each channel uses its own tubes.

PC, I would not mix and match different tube types in you Pr17. Call CJ. I am sure this is what they will tell you as well.

[Puma Cat]

PC, I would not mix and match different tube types in you Pr17.

I don't see why, Ron. From an electrical/physics perspective, the tubes are identical if they are both 6922s.

[ronenash]

Because you will end up with one channel playing through one set of tubes and the other playing through the other set.
Remember, tube tubes serve the left channel and two tubes serve the right channel. Its not the case that each tube serves both channel as some have mentioned.
In any case you end up paralleling sections of different tubes with slightly different electrical characteristics and the result will be drain current flowing between the tubes. For the same reason its not recomended to use different battery types in electrical equipment.

Hope this clarifies my point without getting too technical.

[turntable]

I am almost sure this is not the case. Four parallel triods can be achieved by paralleling the 4 sections of two tubes. If I remember correctly this is how CJ does it to avoid crosstalk between the channels. Channel seperation will be much better when using seperate tubes for each channel. Also noise does not pass from one channel to the other when each channel uses its own tubes.

PC, I would not mix and match different tube types in you Pr17. Call CJ. I am sure this is what they will tell you as well.


Correct, I believe this is how cj designed the pre amp. That is why in the ART each chassis had 5 paralled 6922's for each channel.

Stephen.

To find out which tubes are left and which are right, you can always do the cheating, way and tap the tubes and see if it comes through the right of left channel.:thumbsup:

There is no issue having different brand 6922's, as long as there is one of each in each chanel. The worst that can happen is you don't like the combo. I am sure this is clear wirhout getting too technical :D

Go for it and have some fun:-)

[Joe Appierto]

[QUOTE=turntable;257334]Correct, I believe this is how cj designed the pre amp. That is why in the ART each chassis had 5 paralled 6922's for each channel.

I'm sorry to have passed on incorrect information :o

[turntable]

[QUOTE=turntable;257334]Correct, I believe this is how cj designed the pre amp. That is why in the ART each chassis had 5 paralled 6922's for each channel.

I'm sorry to have passed on incorrect information :o

Joe, I am sure nobody will hold it against you :D

Especially with all your real life experience on lots of tube rolling.

[Rafale]

Thanks for the correction gents :yes:
so for the best channel balance you need tight tube matching

[Rafale]

how do you like your retubed Prem 17 Stephen ?

[Puma Cat]

Hi Philippe,
So good so far...stiil listening for the differences, but there's quite a bit more presence, fullness, and detail, as well as inner detail. The bass is notably more forceful and tighter, which is surprising just from swapping out preamp tubes. The tubes are cryo'd, still sussing out the qualities the cryo treatment bring to the table...