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EQUIPMENT FORUMS >> TORII MK IV >> Rectifier tubes
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Message started by jmac7 on 03/03/14 at 16:12:05

Title: Rectifier tubes
Post by jmac7 on 03/03/14 at 16:12:05

Hi, all. I am new here so please bear with me if this question has been answered before. Can I use 274B rectifiers in my MKIV. I am using Sylvania 5931's , 1956 vintage at the moment. I don't have any complaints with these but you know how it is, always looking for something better.

Title: Re: Rectifier tubes
Post by Lon on 03/03/14 at 16:20:56

Hi jmac,

We'll not jump on you as you're a newbie. :)

I think the answer is "Yes, you can use 274B rectifiers in the Mk IV." Though the tubes may be a bit stressed and as a result not last as long as normally they would in a circuit more designed for them.

There is a 274B made by Valve Audio (and I believe Shuguang) which is electrically more like a 5U4G rectifier and works quite well in the Mk III and most likey the Mk IV. They don't seem to be stressed by the circuit; at one time Steve was sending these with CSP2+ preamps.

Title: Re: Rectifier tubes
Post by jmac7 on 03/04/14 at 13:52:33

Thanks for the info!!

Title: Re: Rectifier tubes
Post by will on 03/05/14 at 20:24:47

I recall it similarly as Lon. If you search Steve Deckert's posts for 274B, you will hopefully find more details, but the traditional 274Bs, being expensive and vulnerable to the circuit electronics, they seem a little sketchy to me. Some folks have had problems with the Valve Art 274B flashing in the MKIII. I have had Valve Arts in the MKIV, but with EL34 or Psvane 5881s. I think the fit is too tight with the Tungsol KT66s. They have an interesting "big" open feeling. Also, as with the MKIII the 40s and 50s RCA 5U4G-STs tend to work very well and fit with the bigger power tubes.

I have not tried the Sylvania 5931s in the MKIV yet, but in the MKIII they sound very accurate, open, and refined, but almost to the point of "too good" for me. Alternately, I find most RCA-STs (and the Valvo 274) less rigid with more textures, harmonic and ambient info.

Rectifiers are great to play with though! I have a ridiculous number of them!

Title: Re: Rectifier tubes
Post by Rivieraranch on 03/06/14 at 03:01:43

I am running 1950's RCA 5Z3's through adapters and they sound rich and fine.