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Post subject: safe to use ss rectifier drri
Posted: Sun May 25, 2014 7:02 pm
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5yr. Old drri with JJ 6V6's.
Current plate voltage 414 volts with rectifier tube, biased 53% idle.
Will the extra B+ put strain on caps or other components over time? Worried about coming off stanby.


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Post subject: Re: safe to use ss rectifier drri
Posted: Sun May 25, 2014 7:14 pm
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I'd use a tube rectifier. There is this seller on EBay selling Philips/Sylvania mil spec 5AR4 (labeled 5V4GA). These are real NOS 5AR4/GZ34's. And they last forever. So you may only need one for the life of your DRRI.

You will keep the 5AR4/GZ34 slow start-up and the B+ in proper range. With the desired voltage sag in the PSU the amp was designed around.

I've now used about 8 of these tubes in various amps. B+ and all other readings follow Mullard and Sylvania 5AR4/GZ34 specs in the same amps.

Not related to seller. :mrgreen:

http://www.ebay.com/itm/5AR4-Rectifier- ... 1c4034d550


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Post subject: Re: safe to use ss rectifier drri
Posted: Sun May 25, 2014 8:04 pm
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I've now used about 8 of these tubes in various amps. B+ and all other readings follow Mullard and Sylvania 5AR4/GZ34 specs in the same amps.

The stock GT Fender rectifier tube, I believe is Rusian....and the amp sings.
Could you elaborate on the differences between this and the Mullard/Syvania specs?
(btw......I live near enough to the Emporium Sylvania plant, that I've gone there a couple times just to poke around.)


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Post subject: Re: safe to use ss rectifier drri
Posted: Sun May 25, 2014 10:36 pm
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Many ppl & several other boards states that the Chinese made "GZ34" handles current needs well, but not high voltage. The Sovtek the other way around. As least, compared to the Mullard GZ34 or Sylvania/GE 5AR4. The life of the original GZ34/5AR4 was overall better than the usual modern product (made from 1980's to now).


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Post subject: Re: safe to use ss rectifier drri
Posted: Sun May 25, 2014 10:43 pm
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How many, exactly the same threads do you need? :roll:

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Post subject: Re: safe to use ss rectifier drri
Posted: Mon May 26, 2014 7:34 am
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My question was whether "it is safe" to use a solid state rectifier on the drri, not necessarily the merits of different rectifier tubes.....although doesn't hurt to know.
Specifficcly, does the additional b+ exceed cap and other amp components.
An answer seems to indicate "no".


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Post subject: Re: safe to use ss rectifier drri
Posted: Mon May 26, 2014 7:46 am
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It depends on the solid-state sub you are using. Some ppl say that the Weber Copper cap (WZ34) put out less B+ than a healthy GZ34. I've never used a WZ34, in a guitar amp.

http://www.thegearpage.net/board/archiv ... 11663.html

Other substitutes run no dropping resistor (to mimic sag) and run higher B+. Many run rather cheap solid-state diodes. I'd run UF4007 in series with the tube rectifier, if safety from shorts is what you are looking for. The UF series are faster switching and much quieter. They cost pennies more than the stock 1N4007.

I've only seen and heard this ss mod in old Dynaco ST-70 hi-fi amps. The ones that used a tube GZ34 to drive four EL34's. These amps have to have very strong rectification, both B+ and current supplied. And are notorious for arc-over with cheaper tube rectifiers.

Anyhow, the tone does change with solid-state. Stiffer. Some say a bit more "clinical." Which I interpret as sterile. But, tone is such a personal matter, maybe you'd like this tone over tube rectification. You need to find out for yourself in your amp. In any event, the DRRI output stage doesn't require the mA that a Dynaco ST-70 needs. So, arc-over shouldn't be as big a problem. As long as you buy a selected & tested new issue. Or a truly high testing or NOS GZ34/5AR4.


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