CJ premier 11A tubes

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Neilert
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CJ premier 11A tubes

Post by Neilert » Mon Jan 11, 2016 8:32 pm

Hello All-
I recently set up a Premier 11A as my first tube amplifier and have a few questions.

The filaments do not glow at all on the two sovtek 5751 tubes, but they are hot.
3 out of 4 of the 6560 tubes have a blue fluorescence.
The right speaker channel is louder than the left by quite a bit.

I ordered new 5751's to see if the the filaments will glow.

Would the 5751's not working cause my balance problem?
Should I check something else before I insert new 5751's?
Any concern about 3 tubes blue glow, and one without?

Thank you!
Neil

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Re: CJ premier 11A tubes

Post by admin » Mon Jan 11, 2016 8:36 pm

Not very familiar with the Premier 11A. I can say that not all tubes glow uniformly. Have you tried to swap the current tubes around to see if the channel volume changes?
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Neilert
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Re: CJ premier 11A tubes

Post by Neilert » Mon Jan 11, 2016 9:52 pm

Not yet-
I will try switching them around when they cool off. Thank you for the suggestion.

Neil

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Re: CJ premier 11A tubes

Post by Big Dog RJ » Tue Jan 12, 2016 9:15 am

Hey Neil,

No real drama's here mate. Plenty of experience with these tubes. It is regardless of the amp.

1. Output tubes glow in various colors- blue, purple, orange tips, greenish tints etc., the main thing to look for is that the entire grid is not "red hot" like an iron or piece of hot amber. If the whole grid is glowing red from top to bottom, then the bias needs adjusting (turn the bias down) or that tube needs replacing asap! Switch the amp off immediately and replace that tube straight away. What it means is that the bias current is not able to hold any longer and the tube is weak or dying, this can even happen to brand new tubes that have had a long air travel or unpleasant flight.

2. If the tubes are glowing blue or purple, that's actually a good thing, means they are running fairly cool, and not red hot. Also means, your bias is set correctly. BTW, have you checked the bias recently?

3. The smaller tubes, such as input and driver tubes, hardly glow. If they glow bright or dull it doesn't mean a thing. It is due to the "getter" silver lining on the top of the tubes that sometimes covers up the glow. If you're concerned just replace the smaller tubes (don't cost much) and they're good to go for at least 4-5 years. It is the larger output tubes that only have around 2000 to 3000 hours of life (typically 3 years of useful life).

4. I've had smaller tubes (input tubes) on my Prem11A, Prem 12's and MV60SE that hardly glow. Only if I was to get up close and cover my hand over them would I be able to notice a very dim glow at the top filaments- this is normal.

Don't stress- tubes are the safest output devices you could have in a system. if one fails, only that tube needs replacing. Very rarely would it take out a board or some nearby circuitry, unless it was a more serious problem, which I have had the pleasure/pain of experiencing during my silly curious days of audio obsession. A very costly ride, at one point I even blew up the large output transformers on my Manley's thanks to my ignorance of biasing with multi-meters. Thankfully, cj doesn't require multi-meters, only a slight adjustment with the special "wand" and magic!
You can also use a flat head screwdriver, just make sure you are touching the bias adjustment pot and not the periphery, or else another wonderful new years light show will take place- been there as well!

Let us know how it goes?
Cheers, RJ

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Re: CJ premier 11A tubes

Post by Neilert » Tue Jan 12, 2016 2:12 pm

Thanks RJ- sounds like these units don't self destruct easily.
I'll put in the new small tubes and see if it solves the balance problem.
I have the plastic bias screwdriver and set bias when the tubes were installed.

take care,
Neil

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Re: CJ premier 11A tubes

Post by Neilert » Fri Jan 15, 2016 8:37 pm

Update: I replaced the two Sovtek 5751 tubes. Neither heating filament glows orange in the new 5751's, but the balance volume between the left and right channels is even now. Whatever the problem was seems to be fixed.

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Re: CJ premier 11A tubes

Post by Big Dog RJ » Sat Jan 16, 2016 12:12 am

Ah ha! there you go. I had a feeling it would have been the smaller tubes, although several areas could have accounted for this imbalance.
Judging from the pics of your prem 11A, I think the output tubes are fine. I can see that out of the 4, only 3 do have that slight blue tint and the other pretty much nothing. Having said that, all the tubes are fine from top to bottom i.e. none of them are glowing "red hot" in the middle grid-section, just an orange glow at the top filament and bottom plate, which is normal.

Just a suggestion if possible: apart from the 5751's (input tubes) that you've changed, I would also replace the driver tubes as well (6FQ7/6CG7)- just to ensure that there is an overall balance in the front end of the amp. Also, changing both input & driver tubes brand new, would be good to go for at least 4-5 years or longer.

During this period, as and when you check the bias on the output tubes, you will notice gradual degradation. Replacing them in matched pairs would be better. cj offers a set of quad matched tubes, which is an ideal replacement set for prem11's and others with similar topology. You could also buy elsewhere for less. 6550C's are not hard to find but you don't need to change these just yet. Keep an eye on that bias and the tubes itself.

Ideally keep your older driver tubes 6FQ7's as spares and chuck out the 5751's, they're no good. If you do happen to replace any of the 6550C's, you could keep them as spares as well since they still would have some life left in them.

Having that balance thing sorted out now would really make a difference, enjoy! Must be sounding pretty dam fine with that Turntable.
Cheers, RJ

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Re: CJ premier 11A tubes

Post by Wildcat » Mon Apr 03, 2017 5:06 pm

Do the 12AX7 have too much gain to use in the 11A? Only because I can find a lot more replacement options for those, vs. the 5751.
C-J PV-14L/C-J Premier 11/Vandersteen 2Ce

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Re: CJ premier 11A tubes

Post by Big Dog RJ » Wed Apr 05, 2017 3:01 am

Hey mate,

Cannot remember ever substituting any tubes when I had the prem 11A, too far back mate, memory is fading like those electrolytic caps, ha!
Too much gain shouldn't be a major issue, unless you were using a horn / horn loaded transducer, where the sensitivity rating is greater than 98dB into the 3 digits figure, that would cause a lot of hissing from the tubes, plus unnecessary noise. At least the ones I have listened to such as Avant Garde, Tannoy and Acapela's, would hiss like crazy, unless proper gain matching was achieved. Once that is done, the sound can have that sublime balance.

Also depends heavily on the preamp (dedicated linestage); if the pre's gain is low, then perhaps this could be compensated with higher gain input/driver tubes on the power amp. Hence, if the pre's gain is fairly high then no worries at all, the standard tubes should work just fine.

I would further investigate into the exact tube requirement you're after that is to your liking. Also, maybe a particular store who specialises in all electron tubes, could lend a few just for you to try out. That way you'd know for sure of which ones work really well and deliver that total synergy.

Trust you find something great, cheers
RJ

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