Who's done a switchable rectifier?

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leadfootdriver
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Who's done a switchable rectifier?

Post by leadfootdriver »

Some of these power transformers come with the tube rec taps. It seem like it would be easy to add a DPDT toggle so you could select tube or silicon rectification.
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Luthierwnc
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Re: Who's done a switchable rectifier?

Post by Luthierwnc »

you might try this:

sh
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Colossal
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Re: Who's done a switchable rectifier?

Post by Colossal »

I implemented such a switch on a 6V6 Plexi build. Academically, it was interesting to be able to hear the difference between tube and solid state but ultimately did not find the mod very useful as I preferred the solid state dynamic (higher voltages) over the tube rectifier and just left it. I love a good tube rectifier though so I think it depends on the amp.
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Kagliostro
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Re: Who's done a switchable rectifier?

Post by Kagliostro »

Right schematic

see page 6 of this file for a "near the same" but a bit different approach
(different switch)

http://home.comcast.net/~seluckey/amps/ ... apbook.pdf

Never put the switch between transformer and [tubes / SS rectifier]

this will burn the tube

Kagliostro
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

Kagliostro wrote:Right schematic

see page 6 of this file for a "near the same" but a bit different approach
(different switch)

http://home.comcast.net/~seluckey/amps/ ... apbook.pdf

Never put the switch between transformer and [tubes / SS rectifier]

this will burn the tube

Kagliostro
Ah, so you parallel the AC taps, and switch the DC out. Thanks brother!
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

Luthierwnc wrote:you might try this:

sh
Not sure I want both at the same time. I might not even like the tube rec.
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

Colossal wrote:I implemented such a switch on a 6V6 Plexi build. Academically, it was interesting to be able to hear the difference between tube and solid state but ultimately did not find the mod very useful as I preferred the solid state dynamic (higher voltages) over the tube rectifier and just left it. I love a good tube rectifier though so I think it depends on the amp.
THat's pretty much how I feel about it. The taps are there, so might as well hook them up, even if I might not like it.
sixstringer
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Re: Who's done a switchable rectifier?

Post by sixstringer »

Here' how I've done it, using 4 1N4007 diodes. Because the rectifier tube only uses 4 lugs of the 8 available on a octal socket, you can use the other four lugs as terminal lugs for the diodes and build the SS circuit right on the back of the socket. I've found that using a NOS tube is the key to having best selection of usable tones. The NOS 5Y3 tubes I've used (Sylvania & RCA) have produced 35-40 volts less than a new Sovtek, making for a "browner" tone. Using the new manufacture tube produced voltage similar to the SS circuit and the tonal difference between the tube and SS rectifier is MUCH less discernible. The SS circuit produces a little more volume, slightly more punch in the mids and tighter bass. Both the tube and the solid state circuits sound good, just different. Recently NOS 5Y3s have be hard to find.
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

sixstringer wrote:Here' how I've done it, using 4 1N4007 diodes. Because the rectifier tube only uses 4 lugs of the 8 available on a octal socket, you can use the other four lugs as terminal lugs for the diodes and build the SS circuit right on the back of the socket. I've found that using a NOS tube is the key to having best selection of usable tones. The NOS 5Y3 tubes I've used (Sylvania & RCA) have produced 35-40 volts less than a new Sovtek, making for a "browner" tone. Using the new manufacture tube produced voltage similar to the SS circuit and the tonal difference between the tube and SS rectifier is MUCH less discernible. The SS circuit produces a little more volume, slightly more punch in the mids and tighter bass. Both the tube and the solid state circuits sound good, just different. Recently NOS 5Y3s have be hard to find.
That looks cool. What about the GZ34, and the 5U4G? Could I just plug and play any of these along with the 5Y3?
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Colossal
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Re: Who's done a switchable rectifier?

Post by Colossal »

leadfootdriver wrote:That looks cool. What about the GZ34, and the 5U4G? Could I just plug and play any of these along with the 5Y3?
You can swap rectifiers so long as a) you do not exceed the tube's voltage and current maximum and b) your tube rectifier winding can deliver the necessary current. A GZ34 has the least voltage drop, followed by the 5U4, then the 5Y3 which drops quite a bit. However, the 5Y3 can't deliver as much current as the other two.

Here's a chart Mark Fowler provided:
http://ampgarage.com/forum/files/rectif ... le_656.pdf
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

Colossal wrote:
leadfootdriver wrote:That looks cool. What about the GZ34, and the 5U4G? Could I just plug and play any of these along with the 5Y3?
You can swap rectifiers so long as a) you do not exceed the tube's voltage and current maximum and b) your tube rectifier winding can deliver the necessary current. A GZ34 has the least voltage drop, followed by the 5U4, then the 5Y3 which drops quite a bit. However, the 5Y3 can't deliver as much current as the other two.

Here's a chart Mark Fowler provided:
http://ampgarage.com/forum/files/rectif ... le_656.pdf
NICE! 'Looks like I'm in spec for an Express build. I was looking at some tube date sheets, but was having a little trouble decrypting them. :( 8)

Franks tube pages is a great resource.

http://scottbecker.net/tube/sheets/093/5/5Y3GT.pdf

http://scottbecker.net/tube/sheets/137/5/5U4G.pdf

http://scottbecker.net/tube/sheets/163/g/GZ34S.pdf
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Colossal
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Re: Who's done a switchable rectifier?

Post by Colossal »

leadfootdriver wrote:NICE! 'Looks like I'm in spec for an express build. I was looking at some tube date sheets, but was having a little trouble decrypting them. :( 8)
If you are thinking of putting a tube rectifier in an Express build, it's an interesting experiment, although it will change the response of the amp. The Trainwreck power supply relies on the compression generated by sagging the voltage across the 1k/25W power resistor between the plate and screen power capacitors. The plate voltages are kept relatively constant due to the fast transient response of the solid state rectifier (and 80uF reservoir capacitance). Putting a tube rectifier into the equation will cause sag across the whole amp, and then further sag across the screens and preamp when the amp is under load. This would change the base operating voltages if you are using the usual 300-0-300 secondary winding.

My Liverpool test amp has a GZ34 rectifier and while it does sound sublime, I used higher secondary voltage to compensate for the voltage drop caused by the GZ34. That said, my 'permanent' Express and Liverpool amps will be built stock with a solid state rectifier as I believe it is a necessary and important part of the Trainwreck equation.

I'm not trying to talk you out of it Leadfoot, just passing along my (limited) experience with using a tube rectifier in a TW build. As many have pointed out, variants are cool and part of making something original, but any deviation from the model circuit does seem to alter something fundamental and intrinsic to the TW sound/feel/magic.

KF built a single-ended amp he called the Dirty Little Monster. I believe Joe Walsh and Dr. Z have one. It used a Mullard GZ34 rectifier. I'm saving some in the event that more information comes to light on that circuit!
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leadfootdriver
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Re: Who's done a switchable rectifier?

Post by leadfootdriver »

Colossal wrote:
leadfootdriver wrote:NICE! 'Looks like I'm in spec for an express build. I was looking at some tube date sheets, but was having a little trouble decrypting them. :( 8)
If you are thinking of putting a tube rectifier in an Express build, it's an interesting experiment, although it will change the response of the amp. The Trainwreck power supply relies on the compression generated by sagging the voltage across the 1k/25W power resistor between the plate and screen power capacitors. The plate voltages are kept relatively constant due to the fast transient response of the solid state rectifier (and 80uF reservoir capacitance). Putting a tube rectifier into the equation will cause sag across the whole amp, and then further sag across the screens and preamp when the amp is under load. This would change the base operating voltages if you are using the usual 300-0-300 secondary winding.

My Liverpool test amp has a GZ34 rectifier and while it does sound sublime, I used higher secondary voltage to compensate for the voltage drop caused by the GZ34. That said, my 'permanent' Express and Liverpool amps will be built stock with a solid state rectifier as I believe it is a necessary and important part of the Trainwreck equation.

I'm not trying to talk you out of it Leadfoot, just passing along my (limited) experience with using a tube rectifier in a TW build. As many have pointed out, variants are cool and part of making something original, but any deviation from the model circuit does seem to alter something fundamental and intrinsic to the TW sound/feel/magic.

KF built a single-ended amp he called the Dirty Little Monster. I believe Joe Walsh and Dr. Z have one. It used a Mullard GZ34 rectifier. I'm saving some in the event that more information comes to light on that circuit!
Thanks for the heads up! Maybe I could use a DPDT to switch in a choke with the tube rec??? :lol:

This stuff can get crazy with the constant mods...
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selloutrr
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Re: Who's done a switchable rectifier?

Post by selloutrr »

Shouldn't you disconnect the voltage to the rec tube when not in use to prevent wear?
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Colossal
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Re: Who's done a switchable rectifier?

Post by Colossal »

leadfootdriver wrote:Thanks for the heads up! Maybe I could use a DPDT to switch in a choke with the tube rec??? :lol:

This stuff can get crazy with the constant mods...
Yes, modding can get crazy indeed. I went through a phase where I had a lot of mod switches on my amps. I think this helped me to answer the questions of what something sounded like over another and while it was very useful for where I was in ampbuilding, ultimately, I have adopted a more simplistic approach. I was told early on by Mark Huss (something of an 'involuntary' mentor to me -- thanks Mark :wink:) to voice the amp once and voice it right the first time. This is sage advice. In other words, mods are nice but invariably, there are very few that are worth doing and as players we most often find one setting and leave it there. I have also found that more switching in the signal path sometimes can degrade the overall tone or lead to instability. I had to find this out firsthand even though I was told up front that this would be the outcome.

With the Trainwreck design, its virtue and purity in tone is due to that simplicity. I get that now having built and heard a Liverpool first hand. I can't believe the clarity and lament what I've been missing all this time! But I can't help but feel that I had to go through all that I did with other builds and experimentation to arrive precisely where I am right now. I'm looking forward to building my Express and Liverpool!

Sorry for the philosophical digression!
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