5e3 - Solid State Rectifier

Wally

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Mcentee, the last tweed Pro I owned was a 5B5 that I resurrected. It sounded fantastic.....and was dissipating a bit over 52%. I found that perhaps a bit odd, but there was arguing with the sonics. Perhaps Leo was not looking for all of the heat that could be had????? Anyway, it had great frequency response. Great cleans with articulate lows. When pushed, it had very good breakup. I never gave a thought about lowering that resistance in the bias circuit because I simply could not justify changing the sound.
What would a different set of tubes have done? It would have been interesting to have had some HOT 6L6’s to try in the amp......for curiosity’s sake, I suppose. But again.....I was not driven to change anything about the amp.
The Pro Sonic uses a 220ohm for the cathode biased option, and I have measured 100% plate dissipation in them.
GZ34/5AR4....?????second half of the 1950’s is the first time I have seen them. The first 5F6 Bassman use the 83 rectifier. The second version used the GZ34....1957 or so, iirc. Leo Fender used two 5U4’s in the low power 5E8A Twin to make the amp stouter/tighter. If you pull one of them, that amp becomes something more like the 5E5A Pro/5E7 Bandmaster/5F4 Super Amps.
 

bftfender

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A plug in SS rectifier does not have to be built to emulate a tube. Weber..and others...sell straight up solid state plug ins without the emulation...no resistors.
That said, I like the ability to switch from tube to SS rectification.
yes it is a wonderful thing ! 2 dif amp responses on the flip of a switch.
 

mcentee2

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Mcentee, the last tweed Pro I owned was a 5B5 that I resurrected. It sounded fantastic.....and was dissipating a bit over 52%. I found that perhaps a bit odd, but there was arguing with the sonics. Perhaps Leo was not looking for all of the heat that could be had????? Anyway, it had great frequency response. Great cleans with articulate lows. When pushed, it had very good breakup. I never gave a thought about lowering that resistance in the bias circuit because I simply could not justify changing the sound.
What would a different set of tubes have done? It would have been interesting to have had some HOT 6L6’s to try in the amp......for curiosity’s sake, I suppose. But again.....I was not driven to change anything about the amp.
The Pro Sonic uses a 220ohm for the cathode biased option, and I have measured 100% plate dissipation in them.
GZ34/5AR4....?????second half of the 1950’s is the first time I have seen them. The first 5F6 Bassman use the 83 rectifier. The second version used the GZ34....1957 or so, iirc. Leo Fender used two 5U4’s in the low power 5E8A Twin to make the amp stouter/tighter. If you pull one of them, that amp becomes something more like the 5E5A Pro/5E7 Bandmaster/5F4 Super Amps.


I love the way these threads can get semi-off topic and throw up gems for consideration, this is very interesting , thankyou :)

Firstly, judging by the 5e3, my first real exposure to amp building, I thought the first principle was to beat the living crap out of the output tubes!!!!! Lol

Secondly, the Prosonic does look a weird beast - online schematics I can find show a fixed bias to the grids, or cathode bias (?) along with rectifier options

If this is the one I am thinking of, I am sure I have read it is thought to be a fender oddity amp all round.
 

schmee

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6v6 at the moment is running at 365v plate, 20v cathode through a 257r cathode resistor.

Just about safe 100% ish dissipation.

If I take the 5y3 out and put the gz34 then plate voltage jumps to 420v, cathode 24v, through the same resistor.

Way way over spec.

I would like to see if I can hear the crisper response from the gz34 ( lower internal resistance) vs the 5y3, i.e. Less sag under pressure, but not kill the 6v6 whilst doing it:)

My PT and OT are over spec anyway so they can cope with the extra "pull" and have increased the filter caps anyway. Also using JJ 6v6s for this tweak.
My BF Deluxes all run about 460V .... and sound great there! Not sure if that will be true with the Tweed circuit, but.. with the $10 plug in it's easy to find out fast.
 

mcentee2

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My BF Deluxes all run about 460V .... and sound great there! Not sure if that will be true with the Tweed circuit, but.. with the $10 plug in it's easy to find out fast.

True, but high Plate voltage isn't the whole story :)

I bet yours is fixed bias to still be within dissipation limits.
 

Wally

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I love the way these threads can get semi-off topic and throw up gems for consideration, this is very interesting , thankyou :)

Firstly, judging by the 5e3, my first real exposure to amp building, I thought the first principle was to beat the living crap out of the output tubes!!!!! Lol

Secondly, the Prosonic does look a weird beast - online schematics I can find show a fixed bias to the grids, or cathode bias (?) along with rectifier options

If this is the one I am thinking of, I am sure I have read it is thought to be a fender oddity amp all round.

I broUgh up thenPro Sonic due to its variety in rectification and biasing...which is connected to your thread. The Pro Sonic is an impressive amp. IMHO, it is one of the best Fenders regardless....and I have owned a large number of Tweeds, brown, BF and SF maps.
Cathode bias/tube rectification, fixed bias/tube rectification, and solid state rectified fixed biased options are available on one three way switch.
Off subject...the topography of the circuit is actually the basis for all of the Blues/Hot Rod amps and for the overdrive modes of the SuperSonic amps. It is loosely based on the 5F6A preamp...2 gains prior to the tone stack...with gain stages dropped into the path to yield 4 tube gain stages prior to the one stack. This general approach is how most high gain amps go About high gain.....the Soldano SLO has 5 gain stages prior to the tone stack.
If you are ever around one, check it out carefully. It is a very versatile amp....everything from old school Tweeds to surf to high gain. It can do almost anything one wants to do.
 
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No457 Snowy

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I have a GZ34 Rectifier in my 5E3 build, it also has a Deluxe Reverb Power Transformer. I run JJ6V6 tubes and the Plate voltage is at 360 volts. I have it dialled in there by using a Zener string on the PT Red/Yellow Centre tap to ground. It still uses the stock 250 Ohm cathode resistor. The amp sounds fantastic, clean, snappy, tight, very punchy, dynamic and loud, like a very beefy 5E3 tone without the sag.

IMG_zener%20string.JPG
 
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Bill Moore

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I too used a DR PT, and a GZ34 in my 5E3 build, thinking I wanted a little more headroom. I did have to change the resistor, to get the bias set. Since I also added a switched "fixed" bias circuit, I plan to try a 5Y3 when I get some time, and see what I get then.
(The GZ34 cathode bias still breaks up sooner than the "fixed" bias)!
 

Wally

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I too used a DR PT, and a GZ34 in my 5E3 build, thinking I wanted a little more headroom. I did have to change the resistor, to get the bias set. Since I also added a switched "fixed" bias circuit, I plan to try a 5Y3 when I get some time, and see what I get then.
(The GZ34 cathode bias still breaks up sooner than the "fixed" bias)!

And...IF you went from that GZ34 to solid state rectification, the breakup point and characteristics would change as well.
Pro Sonics are great amps if only for the ability to experience the difference between biasing and rectification, imho.
 




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