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Topic: Tube or Diode Rectifier? |
James Collett
From:
San Dimas, CA
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Posted 18 Sep 2018 11:51 am |
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Hi All,
I'm getting ready to build a Fender-style amp for double-duty on guitar and PSG. I'll be more or less copying a AB763 Fender Pro schematic, except for the tremolo and a few preamp tweaks. My dilemma is this: do I stick with tube rectification or go with solid state? My concerns are, in no particular order (1) short term and long term costs/tinkering time, and (2) keeping a good compromise between a nice tubey response and the required versatility in tone I'll need to accommodate guitar and steel.
Is a tube rectifier really all its cracked up to be?
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James Collett |
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b0b
From:
Cloverdale, CA, USA
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Posted 18 Sep 2018 12:18 pm
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As I understand it, a tube rectifier has a slower response time. The power lag or "bounce" sounds very musical on hard-hitting power chords, which is why rock guitarists prefer it.
On pedal steel, though, it never thrilled me. Mesa/Boogie amps had a switch "Vintage/Modern" that switched from tube rectifier to diodes. The Modern (diode) setting always seemed more responsive to me.
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-𝕓𝕆𝕓- (admin) - Robert P. Lee - Recordings - Breathe - D6th - Video |
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James Collett
From:
San Dimas, CA
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Posted 18 Sep 2018 12:51 pm
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Thanks b0b. That's kind of what I thought. I realized too that my transformer isn't tapped for a rectifier tube per the schematic I'm following, so I think that settles it right there.
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James Collett |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 18 Sep 2018 2:39 pm
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I am not a great guitarist by any means, but the AB763 Twins were SS rectified. I have a Weber "copper cap" rectifier in my DR clone, and cannot tell the difference with a GZ34 rectifier tube. (You do have to reset the bias).
(I will also admit that the VA fitted me with hearing aids this year, so I could be missing something that others might hear!) |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 18 Sep 2018 3:09 pm
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| James Collett wrote: |
| Thanks b0b. That's kind of what I thought. I realized too that my transformer isn't tapped for a rectifier tube per the schematic I'm following, so I think that settles it right there. |
Well, if you wanted a tube rectifier, I think you could use a standard 6-volt tube, like a 6AX5. That would run off the regular 6-volt tap on the transformer, and they're inexpensive and readily available.  |
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James Collett
From:
San Dimas, CA
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Posted 18 Sep 2018 8:21 pm
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Bill, that’s good to hear that you’re happy with a diode rectifier in your build. If I have the smarts to figure out how to make Donny’s suggestion work, I might try a switchable setup with independent bias adjustment—that’ll really be out there! Ha. Time to research rectifying with a 6v tube...
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James Collett |
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Steve Sycamore
From:
Sweden
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Posted 19 Sep 2018 2:12 am
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| Also, different rectifier tubes have different amounts of sag and total voltage drop. I just ordered a GZ34 / 5AR4 to try as an alternative to a 5U4GB. The 5AR4 is much quicker in response and has much less voltage drop. It maybe gives you a really authentic but crisp vintage sound and feel. Even with the 5U4GB, the difference in feel is subtle with my amp and guitars but can feel as if the overall power is less than with a diode rectifier, as it of course is... |
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Peter Harris
From:
South Australia, Australia
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Posted 19 Sep 2018 3:15 am
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My '59 RI Tweed Bassman 4/10 Jensens is 60W with a diode rectifier...45W with a tube...
...prefer the tone of a tube ..
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If my wife is reading this, I don't have much stuff....really! |
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Dale Hampton
From:
Missouri, USA
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Posted 19 Sep 2018 7:03 am
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| Donny's suggestion is a good idea. Good thinking. The only thing is I would check the current rating of the 6v winding of your transformer. Looking at the 6AX5 specs ,it's heater draws 1.2 amps. Hopefully that wouldn't put the total draw on that winding over what it is designed to handle. Just my thoughts. Dale |
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ajm
From:
Los Angeles
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Posted 19 Sep 2018 8:06 am
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No need to thank me for adding even more potential alternatives (or confusion). ;>))
There is a way to add "sag" to a diode rectified amp to "simulate" a tube rectifier by adding a power resistor.
I've seen this several places over the years, but this write up is maybe the best.
In addition this article also delves into other simple mods like altering tone stacks and mid controls, which seem to pop up here every now and then.
And.......this web site has a TON of articles, enough to keep you busy for quite some time.
For the sag resistor discussion, go down about 4/5 of the way through the article.
(In case the link gets messed up the basic path is.....tone-lizard.com, workbench, modifications)
http://tone-lizard.com/modifications/ |
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James Collett
From:
San Dimas, CA
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Posted 20 Sep 2018 6:15 am
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This is all good info--thanks everybody!
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James Collett |
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Steve Pawlak
From:
Arizona, USA
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Posted 20 Sep 2018 7:51 am
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| I built a JTM-45 from TubeDepot that has both, selected by a switch Best of both worlds |
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Jim Sliff
From:
Lawndale California, USA
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Posted 22 Sep 2018 6:18 pm
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I'll chine in - tube rectifiers don't always have noticeable sag - it depends on which rectifier, the output circuit, plate & grid voltages etc.
If you plan the amp well you can use different rectifiers for different situations. The sag changes, but also headroom and overall efficiency. In some cases with some output tubes you may WANT lower plate voltages and a different response.
With a solid state rectifier you have one setting.
Also, if you build it for a tube rectifier in most cases you can use use a plug-in solid state unit as long as the power transformer can handle it and the tubes some additional plate voltages - if the specific unit raises it.
Weber Speakers sells a series of "copper top" soiid-state units with different "tube equivalents".
If you're unsure about which was to go I'd go tube, since you still have the SS option.
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No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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