CJ Tube Swapping

[wspohn]

I am a long time solid state type that has recently dipped a toe into tube gear. I first bought a Conrad Johnson Premier 14 preamp which pleased me (it is a line stage, as I use a separate phono stage). I thought that given that it uses tubes that are modestly priced, I would have a shot at some modest tube rolling to see what differences I could hear, if any.

The stock CJ tubes are 6FQ5A / 6GK5 and the factory likes to supply GEs. I obtained NOS and used with good test results to audition, with no expectations at all.

Results:

Hitachis sounded a bit inferior and closed in

Mullards sounded about the same

RCAs sounded significantly better and more open

Interesting! When I bought a CJ Premier 11a power amp (which I decided I liked more than I did the sound of the Rowland 5 in the main system, although the latter had better bass slam), I decided to do a bit of tube swapping on it. The amp uses four 6550 output tubes which were new when I bought the amp and I decided to leave them alone, a pair of 5751s and a pair of 6CG7s.

I swapped out the 5751s for some Raytheon JAN-5751 black plate windmill getter tubes with excellent results (I’d borrowed a pair from a friend to try before buying) and then added a pair of US Sylvania 6CG7s which also made a small but distinct improvement in sound.
Thus endeth my tube swapping for the time being. I am happy with the results and have thought of eventually trying the same thing on the output tubes. I’ve seen good reviews of Tungsols and of some KT-88s that I gather are direct substitutes. But before getting into that, I thought I’d ask if anyone else had any preferences as far as 6550s go?

And to what degree is the experience with one amp likely to be the same with another? Or are tube results dependent on which amp you are using them in (in which case I doubt I'll find many people with identical tubes/amps to offer advice). All advice gratefully received.

[kcin]

I am a long time solid state type that has recently dipped a toe into tube gear. I first bought a Conrad Johnson Premier 14 preamp which pleased me (it is a line stage, as I use a separate phono stage). I thought that given that it uses tubes that are modestly priced, I would have a shot at some modest tube rolling to see what differences I could hear, if any.

The stock CJ tubes are 6FQ5A / 6GK5 and the factory likes to supply GEs. I obtained NOS and used with good test results to audition, with no expectations at all.

Results:

Hitachis sounded a bit inferior and closed in

Mullards sounded about the same

RCAs sounded significantly better and more open

Interesting! When I bought a CJ Premier 11a power amp (which I decided I liked more than I did the sound of the Rowland 5 in the main system, although the latter had better bass slam), I decided to do a bit of tube swapping on it. The amp uses four 6550 output tubes which were new when I bought the amp and I decided to leave them alone, a pair of 5751s and a pair of 6CG7s.

I swapped out the 5751s for some Raytheon JAN-5751 black plate windmill getter tubes with excellent results (I’d borrowed a pair from a friend to try before buying) and then added a pair of US Sylvania 6CG7s which also made a small but distinct improvement in sound.
Thus endeth my tube swapping for the time being. I am happy with the results and have thought of eventually trying the same thing on the output tubes. I’ve seen good reviews of Tungsols and of some KT-88s that I gather are direct substitutes. But before getting into that, I thought I’d ask if anyone else had any preferences as far as 6550s go?

And to what degree is the experience with one amp likely to be the same with another? Or are tube results dependent on which amp you are using them in (in which case I doubt I'll find many people with identical tubes/amps to offer advice). All advice gratefully received.

No experience with your amps. But I do have a Citation II that uses 6550s or KT88s For New not too expensive the Electroharmonix have good overall balance they take about 30-40 hrs to come to life. More expensive but better balanced are the Genelex.

If you are able to find them and have the pocket book I like the Original Tungsol 6550s nice rugged tube. They will be hard to find NOS all at one place but they are around I have a quad stashed.

Love the Classe amps -- really nice machines.

[Dr.Ears]

N/A

[JCOConnell]

FWIW, I've had good results with NOS smooth plate telefunken signal tubes in my CJ PV-10A preamp ( combined linestage/phonostage )

[MylesBAstor]

I am a long time solid state type that has recently dipped a toe into tube gear. I first bought a Conrad Johnson Premier 14 preamp which pleased me (it is a line stage, as I use a separate phono stage). I thought that given that it uses tubes that are modestly priced, I would have a shot at some modest tube rolling to see what differences I could hear, if any.

The stock CJ tubes are 6FQ5A / 6GK5 and the factory likes to supply GEs. I obtained NOS and used with good test results to audition, with no expectations at all.

Results:

Hitachis sounded a bit inferior and closed in

Mullards sounded about the same

RCAs sounded significantly better and more open

Interesting! When I bought a CJ Premier 11a power amp (which I decided I liked more than I did the sound of the Rowland 5 in the main system, although the latter had better bass slam), I decided to do a bit of tube swapping on it. The amp uses four 6550 output tubes which were new when I bought the amp and I decided to leave them alone, a pair of 5751s and a pair of 6CG7s.

I swapped out the 5751s for some Raytheon JAN-5751 black plate windmill getter tubes with excellent results (I’d borrowed a pair from a friend to try before buying) and then added a pair of US Sylvania 6CG7s which also made a small but distinct improvement in sound.
Thus endeth my tube swapping for the time being. I am happy with the results and have thought of eventually trying the same thing on the output tubes. I’ve seen good reviews of Tungsols and of some KT-88s that I gather are direct substitutes. But before getting into that, I thought I’d ask if anyone else had any preferences as far as 6550s go?

And to what degree is the experience with one amp likely to be the same with another? Or are tube results dependent on which amp you are using them in (in which case I doubt I'll find many people with identical tubes/amps to offer advice). All advice gratefully received.

One problem I found with the 6GK5 was that there was an inverse correlation between sound and longetivity. I really hated that tube and didn't find it lasted long before going noisy. Think that's why cj chose the GE.

IIRC, cj originally supplied Sylvania 6FQ7s but over the years the supply of this tube dried up.

I would look at KT120 output tubes.

[wspohn]

One problem I found with the 6GK5 was that there was an inverse correlation between sound and longetivity. I really hated that tube and didn't find it lasted long before going noisy. Think that's why cj chose the GE.

Makes me long for the days when all I had to worry about with a solid state power amp was the caps drying out in a few decades!