Currrent production octal triodes

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RB
Posts: 126
Joined: Thu Apr 06, 2006 11:36 pm
Location: San Diego CA

Currrent production octal triodes

Post by RB »

I have had an octal based Tweed Bassman/Mashall JTM/JMP style head on my to-do list for a few years and it's time to get it off the list.

One of my goals for any amp I build is to use the best production tubes available for the job. Yeah I know there nothing like NOS but let's face it if your using your amp for living and you fry a tube you don't want spend the time and money finding and qualifying a NOS replacement tube.

Is there anyone out there custom building or doing repair that consistently uses new production octal preamp tubes? I am not not expecting any more than yes, they are close but no cigar. Or maybe the rationale is that your repair client just doesn't have the $$ for NOS and the amp ends up still having octal qualities to some desirable degree using new production tubes.

I have noticed JJ having expanded the their octal offerings. Any info/opinions/experience with those? Any info/opinions/experience with CE Dist. Russian or Chinese offerings?

Do I think I can get custom amp tone quality out of new production tubes?. Yes I do. I have gotten head turning results from new production 12A?7 tubes that many web pundits loath just by altering the plate voltages and bias points and grid leak values.

I made a test bed amp for 9 pin tubes using trimmers and pots so I could change cathode (10k), plate (300k), inter-stage level pots, and various 10watt wire wound in the voltage dropping string to help me dial in tone and break-up. I am interested in doing this with octals as well.

I think for the most part people look at the circuit design as a fixed constant and the tube as a variable (I believe its because we have developed a de-facto attitude of fixing the problem with the NOS tubes. NOS tubes are going away (as far as I am concerned the are gone already).

I want to create the best tone possible with the tubes we can get now. One way I have accomplished this is by altering current designs(making this the variable) to produce similar sonic signatures as the old tube by using new production tubes (now the constant). This will allows me to learn about the operational parameters/curves/characteristics of the new production tubes(the constant). Of course this could lead to different designs for one or two manufacturers that you feel deliver consistent performing tubes but there operating curves are different.

If we can not get stellar results with new tubes then solid state amps will be the TrainWrecks and the Dumble's of tomorrow, Do you really want a future like that?

Well I have done a good job of hi-jacking my own thread and going on a good rant. My apologizes. Maybe a few of you will find it amusing.

Like the Marines I am just looking for a few good new octals.
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M Fowler
Posts: 14017
Joined: Wed Jan 16, 2008 2:19 am
Location: Walcott ND

Re: Currrent production octal triodes

Post by M Fowler »

I use Tung Sol 6SL7 new production preamp tubes in my Fender Bassman 5B6 builds.

Brad Sarno also uses these in his V8 octal preamps as well as many other production amp companies.

There are plenty of NOS on ebay but why risk getting trash labelled as NOS.

Mark
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