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Hello Kevin,
I am using the K&K upgraded ST-70 and now that it's time to replace the original EL34 tubes I'd like to ask for advice on alternative options. Specifically, the Russian 6p3s or 6L6 output tubes in place of EL34?
6p3c russian datasheet:
http://klausmobile.narod.ru/td/data/_6p3s.GIF
(translation)
VA=250V, VG2=250V, VG1=-14V, IA=72mA, IG2=5V, S=6mA/V, K(µ)=150, Ri=25000Ω, Ra=2500Ω, Po=5.5W, P=20.5W, Capacité entre G/A=1pF
Will one of the above tubes work in place of el34?
thank you,
Herman
Follow Ups:
The 6p3c-e is a great tube in the ST-70. I'm running them on my brother's ST-70 with Kevin's kit, sounds really good. Make sure you get the 6p3c-e version, with the coin base, the regular 6p3c doesn't sound very good in comparison. Don't worry about the voltage rating, the Russian specs are super conservative. I've heard of people running them with almost 600V on the plates. The 6p3c-e tubes in my brothers amps have been working fine for several years with about 440V on the plates. They sound really good when run at 21 watts dissipation. Highly recommended
Thanks for the advice I'll give them a try. Is 6L6 another suitable option?
I suggest the 6L6GC for its higher voltage rating.
Kevin Carter
K&K Audio
www.kandkaudio.com
I have used the 6P3S-E in my upgraded ST-70 with an original pwr transformer at about 50mA of bias current and they sound very nice. I suspect that the 6P3S would not have a long lifetime under the same circumstances due to the voltage limitation mentioned in the previous response.
Kevin Carter
K&K Audio
www.kandkaudio.com
I don't think the normal 6p3s will work due to plate voltage limits, but I've used the 6p3s-e with the coin base and it sound quite nice in an ST-70. I suspect it more like a 6L6 than an EL-34 and would be better with a higher primary impedance on the output transformer.
John
De gustibus non est disputandum
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