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FDP Forum / Fender Amps: Vintage (before 1985) / Rectifier tubes



Feb 25th, 2017 10:29 AM   Edit   Profile  

What will be the benefit/downside of replacing the rectifier tube in my '66 Super Reverb with a solid state rectifier?



(This message was last edited by macguy at 12:39 PM, Feb 25th, 2017)



Feb 26th, 2017 09:28 AM   Edit   Profile  

I'm not sure there would be a benefit, as the amp was designed when 117v was the norm. That said, the amp is now running higher voltages than it was designed for. Most people find their ac voltages to be in the 121v-123v range. Have you measured the plate voltage on your power tubes? A solid state rectifier will only increase said voltages.

(This message was last edited by slider313 at 11:28 AM, Feb 26th, 2017)

Doc Sarvis
Contributing Member

USA/Salt Lake City

Tuned Strings and Tight Lines
Feb 26th, 2017 11:41 AM   Edit   Profile  

As I understand it, SS rectifiers have minimal internal resistance which leads to consistent voltage within the operating current range. This provides tighter, less spongy, bottom end. They are also comparatively trouble free. Of the fifteen mostly vintage amps in my collection thirteen of them are tube/valve rectified with only a 1970 Marshall JMP small box and early '80s Mesa Boogie Mark IIC+ having SS rectifiers. If an amp comes equipped with a tube rectifier, I leave it be, but if you believe the bottom end needs firming, give one a try. The correct SS replacement won't hurt a thing.

(This message was last edited by Doc Sarvis at 01:41 PM, Feb 26th, 2017)

Contributing Member

I tried to think

but nothing happened!
Feb 26th, 2017 03:57 PM   Edit   Profile  

SS rectifiers may be more reliable. Your power transformer will run a little cooler. If you get one by Weber, you can select how much sag you want (or no sag). I'm running them in my PR and DRRI.




Feb 27th, 2017 12:29 PM   Edit   Profile  

...so, this one perhaps....?

SS Rectifier for my 1966 Super Reverb?

Contributing Member

So. Cal. USA

Feb 27th, 2017 11:17 PM   Edit   Profile  

The WZ34 will work just fine in your SR. Adjust bias after installation.

This will relieve the power transformer a bit as the 5V heater taps for the rectifier tube will be unused.


It's not just good..

...it's good enough.
Feb 28th, 2017 07:03 AM   Edit   Profile  

I've had a WZ34 in the '68 Deluxe Reverb for several years, now. Works as advertised and the amp sounds amazing.

It should probably be noted that the Weber "Copper Caps" are SS implementations of the old tube rectifiers. Essentially, they model what tubes do with SS components.
They are NOT the same as the old plug-in SS rectifiers - which behave differently than a tube rectifier (including running at higher voltage).



Feb 28th, 2017 09:30 AM   Edit   Profile  


Are the differences in the Weber Copper Caps vs the "old plug in" ss rectifiers a plus or a minus, in your opinion?

(This message was last edited by macguy at 01:46 PM, Feb 28th, 2017)


It's not just good..

...it's good enough.
Mar 1st, 2017 06:23 AM   Edit   Profile  

Huge plus in my mind, macguy.

But it really does depend on what you're going for with the replacement.
With the Copper Caps, you're mimicking the behavior of the tube rectifier that you're replacing. Basically, you get a very reliable version of a rectifier tube that puts less strain on the power transformer.
So, you maintain the characteristics of the stock amp. And that's what I wanted.

If, on the other hand, you want to tighten up the response of the amp and eliminate the "sag" of a tube rectifier, the old SS rectifier is probably what you want.
Just popping in a SS rectifier will raise the voltage levels to the power tubes, but rebiasing will fix that.

And you should rebias (or at least check the bias) whenever you replace the rectifier - whichever replacement you put in there.

FDP Forum / Fender Amps: Vintage (before 1985) / Rectifier tubes

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