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Using 7189's in place of 6BQ5's

Tubes live longer when running in class A at design specifications than when running one moment very cold and the next moment on their toes. Steady does it, somewhere I seem to remember in class AB push-pull maximum dissipation is at approx 70% output. But I could remember wrong.
 
I just checked the progress of the tubes being shipped. It's a bit different from before. Ukraine to Jamaica to NYC. I thought that routing a bit odd. They took a side trip for some ganja I guess. :smoke::biggrin:
 
AmadeusMozart said:
I seem to remember in class AB push-pull maximum dissipation is at approx 70% output. But I could remember wrong.
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No, that is correct, although some like to bias AB amps as low as 60-65%, though that low level won't sound great in many circuits. Class A can be biased up to 90%, though I've seen some say 100% is OK. I stay at 90% for my Class A amps, in part because they have big PTs and OTs.
 
The Rausian made guitar amp I restored was biased to about 65%. It could have been biased hotter, but it sounded best to my son set to 65%. It was hard to find much info on it, but I did find a tube guitar repair shop that worked on them. I was told 65% to 70% was a good place to bias them.
 
Lavane said:
I just checked the progress of the tubes being shipped. It's a bit different from before. Ukraine to Jamaica to NYC. I thought that routing a bit odd. They took a side trip for some ganja I guess. :smoke::biggrin:
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Maybe it meant Jamaica, NYC? There is one in Queens borough...
 
70% is a common setting but it doesn't have to be there. I've got something that performs best audibly and on the distortion meter in the 35% range. I expect those tubes will last an extremely long time. Its also using EFB to control the bias, which is something that didn't exist in the tube heyday.
 
Lavane said:
I just checked the progress of the tubes being shipped. It's a bit different from before. Ukraine to Jamaica to NYC. I thought that routing a bit odd. They took a side trip for some ganja I guess. :smoke::biggrin:
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I have a quad of 6P3S-E coming from Ukraine which have gone to Jamaica too. Sounds like fun.
 
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Blackdog61 said:
I have a quad of 6P3S-E coming from Ukraine which have gone to Jamaica too. Sounds like fun.
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The four 6P3S-E's I bought came well matched. What are you putting them in?
The ones I ordered went into a Russian made guitar amp my son has and really likes.
 
Lavane said:
The four 6P3S-E's I bought came well matched. What are you putting them in?
The ones I ordered went into a Russian made guitar amp my son has and really likes.
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I’m going to try them in my ST-70, biased at 40ma. Expectations are fairly low that they will beat out the RFTs but I’m curious.
 
Blackdog61 said:
I’m going to try them in my ST-70, biased at 40ma. Expectations are fairly low that they will beat out the RFTs but I’m curious.
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I knew someone that used them in a ST-70 years ago. I remember the amplifier sounding really good.
 
I tried them in my Pilot sa260 and did not care for it, but that's just my opinion and you know what those are worth
 
I have had certain tubes sound bad in one amp, and sound fine in another. Using the same KT-88's in my ST-70 vs my M-125 mono blocks is an example.
But everyone has different opinions on sound. If it sounds good to you that's all that matters. I guess I'll find out in a few days whether I like the 6P14P-K's or not.
If not, they were cheap and I'm sure there are a few guitar players that would want them.
 
Lavane said:
I have had certain tubes sound bad in one amp, and sound fine in another. Using the same KT-88's in my ST-70 vs my M-125 mono blocks is an example.
But everyone has different opinions on sound. If it sounds good to you that's all that matters. I guess I'll find out in a few days whether I like the 6P14P-K's or not.
If not, they were cheap and I'm sure there are a few guitar players that would want them.
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I liked them in my 9304 and have Mullards, Telefunken and Raytheon labeled Japanese tubes. They went with that amp when I sold it.
Regarding the 6l6 type, I don’t know how they will fare. They were cheap enough to try and some people seem to like them in the ST-70.
 
Blackdog61 said:
I liked them in my 9304 and have Mullards, Telefunken and Raytheon labeled Japanese tubes. They went with that amp when I sold it.
Regarding the 6l6 type, I don’t know how they will fare. They were cheap enough to try and some people seem to like them in the ST-70.
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My 9304 came with all mallard tubes, but both the 6EU7's and the quad of 6BQ5's are really weak. I have a pair of NOS GE 6EU7's in it now. The 6P14P-E's that were originally in that guitar amp got pushed pretty hard over the years and they held up pretty well. The original quad is still usable, but they are getting weak. I tested them as a 6L6 and comparing the old ones with the new ones the old ones test about half, or a little less compared to new.
 
I am pretty sure the 6P14P-K are just a vibration resistant version of 6P14P and both are rated for 3k hours, not to be confused with the 6p14P-EV variant which is equal to 7189 and rated for 5000 hours. The EV versions have double mica spacers and getter has double post supports and are not the flying saucer type on the 6p14p-k versions. That said they are still nice tubes and are excellent subs for 6bq5.
 
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I do run different el34 class tubes in my two el34 amps for a reason. I just didn't happen to like the 6p3se in either. Never tried in an st70 though
 
petes'picks said:
I am pretty sure the 6P14P-K are just a vibration resistant version of 6P14P and both are rated for 3k hours, not to be confused with the 6p14P-EV variant which is equal to 7189 and rated for 5000k hours. The EV versions have double mica spacers and getter has double post supports and are not the flying saucer type on the 6p14p-k versions. That said they are still nice tubes and are excellent subs for 6bq5.
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Ya, I've seen several lists that were posted showing the life expectancy of the various 6p14p's. A couple listed the K's at 5K hours, some at 3K. Some of these K's being sold are supposed to have been used in Ukrainian subs. Most likely old Soviet subs? Who knows. 3K or 5K hours is fine with me. I did see a date code on a picture of the ones I bought. It looked like 11/71? They're Reflector's with the CCP logo on them.
 
I actually have the K datasheet somewhere but havent seen it in awhile, I will check my other computer and box of documentation for you.
 
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