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scored some free tubes (Read 436 times)
Damien
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scored some free tubes
02/05/14 at 18:08:37
 
A friend was cleaning out a family members house (a hoarder) and discovered under the piles an old tube radio. The family was going to trash it so friend snagged the tubes for me

I put the Zenith 12AT7 in my Taboo and I am liking it a lot. This tube is just a bit smaller in diameter than the JJ or Mullard (new) 12AX7's I have.

Also got an RCA 5Y3GT rectifier I am using in the CSP2+

Other tubes I got that I can't use

a pair of Sylvania 6V6GT power tubes
2 KenRad  6BA6
1 unnamed 6BA6
1 Zenith 6AU6

All made in USA and if I read the date codes right on the KenRad tubes they're from 1948. The others either don't have a date code I can find or don't have one I have been able to decipher
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D-18
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Re: scored some free tubes
Reply #1 - 02/05/14 at 22:28:33
 
Damien, glad you had a chance to try the 12AT7 option in your amp. I  also like the "AT" series in my 2006 era Taboo, always coming back to it despite slightly lower input sensitivity. A word of caution with respect to using 5Y3 rectifiers in both the CSP and Taboo however. Most 5Y3GT's produced after 1955 were designed to work OK into a 20uf filter input cap; the older CSP and Taboo used 33uf power supply input caps, a design compromise which allows for the use of several different rectifier types, but which puts some strain on the 5Y3's and tends to shorten their life span. (When they give up the ghost the fuse generally blows.) The older pre 1955 5Y3G / GT's, although wonderful sounding, are even more delicate since they were designed to load into 10uf caps and I have found tend to have much shorter life expectancy unless the power supply is modified to  accommodate them. Generally the SOVTEK 5Y3's that Steve supplies are a bit more rugged and last longer than other 5Y3 NOS choices. There is less of a life expectancy problem with the 5U4's and 5AR4's which were designed to load into 40uf to 60uf power supply input capacitors; they will occasionally blow, but this tends to be an individual tube quality issue.  8-)  Walt
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Damien
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Re: scored some free tubes
Reply #2 - 02/05/14 at 23:04:09
 
I have preferred the 5y3 tubes over the stock 5U4's. I don't know what year these were made though since all the other tubes in the donor radio were 1948 (that I could identify) I will assume this RCA 5Y3 is also a 1948. I have 2 other 5Y3's both Silvertone and have loved them but don't know the year on them, suspect WWII era from the radio I pulled one from. If they die early I'll know why. They have not shown any problems yet though. Rectifiers are supposed to last longer than the amp they're in, so what constitutes a 'shortened lifespan' for a rectifier?
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Re: scored some free tubes
Reply #3 - 02/07/14 at 00:04:36
 
It is certainly possible for a rectifier tube to last a very long time, even the lifetime of a given amp or beyond, if it is used according to the tube designer's specifications in the design of the amp. I guess in this context any rectifier failure would be considered a shortened lifespan. Based on the handful of schematics I have seen of Steve's amps, his power supply designs seem to favor the use of 5U4's and 5AR4's. Personally, over a period of over 7 years during which I have rolled many different 5U4's, 5AR4's, and 5Y3's in my three Decware amps, I have experienced five 5Y3 failures (three of which were the older 5Y3G) and one 5U4 failure. I do have high power company AC voltage in my area which likely also contributed to this.
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Lon
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Re: scored some free tubes
Reply #4 - 02/07/14 at 00:36:41
 
Oddly, I've been mainly using 5U4G in my Toriis and 5Y3 tubes in my ZP3 and my CSP2 and CSP2+ (in those machines that's the only tube type that seems accurate to me). I've had a few 5U4G failures, no 5Y3.
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Damien
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Re: scored some free tubes
Reply #5 - 02/07/14 at 02:32:47
 
I have had one rectifier fail and it was a 5U4 but it was bad from the factory so I don't think that should count
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