Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dujuarez on September 14, 2015, 04:15:47 pm

Title: Using a solid state rectifier instead of tube rectifier
Post by: dujuarez on September 14, 2015, 04:15:47 pm: I have some transformers that aren't tapped for 5V tube rectifier. Is it possible to use a solid state rectifier instead?
I'm interested in using a solid state rectifier with Hoffman 5F6A Tweed Bassman. In addition, how would I go about doing this?
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: tubenit on September 14, 2015, 06:26:12 pm: Depends on the PT and the center tap. Note that Hoffman sells a plug in solid state rectifier for an 8 pin socket.

Also note you can simply add a 5v transformer which Doug also sells and have a GZ34.

with respect, Tubenit
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: PRR on September 15, 2015, 12:24:09 am: There are rectifier tubes with insulated heaters which can take the 6.3V that the rest of the amp eats and deliver DC at 350V-400V.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: dujuarez on September 15, 2015, 11:28:29 am: I was thinking about using something like what Fender does with diodes and eliminate the tube altogether.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: dujuarez on September 15, 2015, 11:39:44 am: Tubenit, that schematic is exactly what I was thinking about using. What wattage would the 1N4007's need to be?
Also, what determines how many diodes to use? For example the schematic you posted has 4 diodes but the Fender Twin Reverb
has 6. Is it due to the PT being larger?
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: shooter on September 15, 2015, 11:51:34 am: Quote
What wattage would the 1N4007's
In tube amps you're more concerned with the PIV rating, you want a diode that can handle probably twice the B+ rating. the 1N4007 is good for 1000v. Diodes can be arranged as 1/2 wave, full wave, or bridge, pick the one that matches your needs
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: dujuarez on September 15, 2015, 11:57:57 am: Shooter, send me a link explaining the difference between half-wave, full-wave and bridge.

Thanks.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: Commodore 64 on September 15, 2015, 12:17:22 pm: http://www.hammondmfg.com/pdf/5c007.pdf (http://www.hammondmfg.com/pdf/5c007.pdf)

That's a good reference...
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: tubenit on September 15, 2015, 12:36:09 pm: Quote
send me a link explaining the difference between half-wave, full-wave and bridge

Did you know Doug Hoffman has a Library of Information that answers most of the questions you are asking? I would strongly encourage you to look at it and see what is in the Table of Contents with it.

Scroll to the bottom of this page and you will see the link straight to it! Tons and tons of fabulous information there.

I printed the entire thing off years ago and read and reread it and still go back and refer to it.

This is straight out of that Library of Info.

With respect, Tubenit
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: Commodore 64 on September 15, 2015, 02:02:47 pm: Can you explain to a noob why the Hoffman rectifiers appear to have 3 diodes in series where the Hammonds have 1 in the Half wave and full wave diagrams?

Diodes are cheap, I'm more than willing to stack mine that way too, just wondering about the theory/reason why.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: PRR on September 15, 2015, 03:21:55 pm: > the Hoffman rectifiers appear to have 3 diodes in series

That's copied from a 1961 design (likely the standalone reverb), from days when 200V diodes were about the best we could get. The 3-stack gives nearly 600V rating.

Since today a 1,000V diode is as cheap as a 50V diode, we would just use one diode.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: labb on September 15, 2015, 03:27:18 pm: Someone should explain to him the difference in the rectified voltage to expect from a diode rectifier vrs. a tube rectifier.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: shooter on September 15, 2015, 06:14:16 pm: Quote
Someone should explain to him the difference
OR, like most of us have found here, you read, re-read, google, read, come back and ask ?'s, then read :icon_biggrin:
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: PRR on September 15, 2015, 11:08:09 pm: > the difference in the rectified voltage to expect from a diode rectifier vrs. a tube rectifier.

True. A "Tweed 5F6a" with a solid-state rectifier is a very different thing, a 1970s beast (I forget what name Fender put on a 5F6a-like circuit with silicon rects).

Like (sorry) a 1957 Plymouth Fury had a pretty strong engine, but a 1962-1968 Fury had a smaller body and could be had with a MUCH stronger engine (426 Hemi and 440 wedge). One is a hot old car, the other is a monster.
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: tubenit on September 16, 2015, 05:14:40 am: OK, with a PT of 300-0-300 ...................

Using a 5Y3GT, 1.1 x 300 = 330v
Using a 5V4GT, 1.2 x 300 = 360v
Using a GZ34, 1.3 x 300 = 390v
Using a SS rectifier, 1.4 x 300 = 420v

This isn't totally accurate, but a reasonable starting place to think about a few common rectifiers.

I've attached a Tube Data Cheat sheet that LooseChange & I worked on many yrs ago that I still refer to.

With respect, Tubenit
Title: Re: Using a solid state rectifier instead of tube rectifier
Post by: labb on September 16, 2015, 10:20:03 am: I believe that the AA165 Bassman was when Fender went to the diode rectifier. Just a note: re PT selection, don't short yourself on current capacity. And tubenit, I wish I was half as organized with info as you are. Good job.