Changing an SS Rectifier to a tube circuit. Possible?

[tomteriffic]

I was just idly wondering if it's technically possible to change an amp with a solid state rectifier to a tube circuit? I've got a couple of amps that, if they had just a little rectifier "sag" would just be perfect (for me).

Is this possible, short of replacing the power transformer. Following from that is it practicable? The amps I'm thinking of have room on the chassis to get another hole punched, but might have to have their internal circuitry rearranged to make room. But beyond that....

[crunchee]

I'm no expert on amps, but I've heard of people doing it. What amp are you thinking of converting?

Seems to me that you REALLY have to crank an amp to get noticeable levels of sag. How much wattage are you looking at?

The funny thing I've noticed about tube recifiers, is that most everybody seems to prize English-made GZ34s/5AR4s highly, especially since they've been used in great sounding/famous amps; and they're expensive, especially since the original English ones haven't been made in decades. But guess which rectifier tube is said to have the LEAST amount of sag? From what I've been able to find out, the thing that GZ34s are really useful for, is their slow, controlled power-up, when the amp is switched on, and that would be useful if your amp didn't have a standby switch. I dunno if it makes a difference if the amp DOES have a standby switch, though.

[JGale]

Tom.

London Power may have what you are looking for. You are correct. A tube rectifier would drop the voltage a bit much.

http://www.londonpower.com/catalog/index.php?cPath=22

[Turdus]

How does rectifier sag change the tone of an amp, or does it? I thought I read somewhere, that the rectifier does not effect an amp's tone. I always thought the SS rectifier plug-ins, were sold to add an element of reliabilty.

[JGale]

It depends on the rectifier tube. Some are "faster" than others in passing the voltage peak to the circuit. The slow ones give that booooing compression you hear in the first note of Funk49 say.

[tomteriffic]

It depends on the rectifier tube. Some are "faster" than others in passing the voltage peak to the circuit. The slow ones give that booooing compression you hear in the first note of Funk49 say.

This right here. ^^ That slower response, reminiscent of an old smaller amp that has seen better days, is what I'm after. I expect I may have to go the London Power route, but that kind of transient response in a Pro Junior, Fender Excelsior, that kind of thing is what I'm after.

[Jakeboy]

I would sell the amps I have and buy tube-rectified circuits. All I have are tube rectified tweed clones and Tube rectified Marshall's...plus a vintage Valco.

The GZ34 has sag when cranked but not like the tweed Champ used on Funk49....that is a 5y3 struggling to keep up....5e3 Deluxes have this in spades when cranked.

I have GZ34s in 2 amps and prefer those when playing tighter rock.

[JohnnyB]

I don't know if this is generally true, but IIRC the owner/designer of Top Hat Amps told me (about 15 years ago) that I could swap in a 5Y3 for the stock 5AR4 if I wanted more sag, but you couldn't swap a 5AR4 into a circuit designed for a 5Y3 or other slower rectifier. Does this make sense?

And here's a tip if you want a rugged, reliable NOS rectifier tube that doesn't require a second mortgage. Back when I bought my Top Hat, I wanted to replace the Chinese rectifier tube with NOS, but the US- and European-made NOS rectifiers were generally around $150. But I found a NOS RCA Japan 5AR4 for just $25. Fast forward 15 years and today I'm looking over the same vendor, NOS from Europe range from $90 to $500, but they had a Mullard-Japan, made by Mitsubishi, for $50. Unfortunately they're currently out of stock. But the NOS rectifiers from Japan are a good money-saving alternative. These Mullard/Mitsubishi tubes were made for the later production runs of the legendary Dynaco ST-70 tube power amp.

[FrankieIII]

I think THD used to make something called "Reactive Rectifier" that was solid-state but sounds tube.

[Bloozguy]

I would sell the amps I have and buy tube-rectified circuits.

This is probably the best suggestion. Changing from a solid-state to a tube rectifier will probably require a different power transformer which will be both a hassle and expensive.

[anotherfreak]

Tom, Get a Black Pearl! they can be found CHEAP, and are really the bee'znee'z!

Better yet, find me a head, and maybe I can send my 112 combo for yas to see what all the fuss is about

[Brewmaster]

Take a look for rectifier circuit boards, similar to sister boards for computer cards, that retrofit into the amp. I have seen some online for folks looking to do what you want.

There are folks that will custom make a tube rectifier circuit, ptp, similar to what folks do for guitar wiring kits. You can DYI or have a tech do it.

What they cost, I have no idea.

I had discussed conversion kits in the past with a fellow builder but nothing ever came of it. I think because any tech worth his or her salt should be able to do this.

[MCChris]

And here's a tip if you want a rugged, reliable NOS rectifier tube that doesn't require a second mortgage. Back when I bought my Top Hat, I wanted to replace the Chinese rectifier tube with NOS, but the US- and European-made NOS rectifiers were generally around $150.

I'd gladly take out a $150 mortgage.

[JohnnyB]

And here's a tip if you want a rugged, reliable NOS rectifier tube that doesn't require a second mortgage. Back when I bought my Top Hat, I wanted to replace the Chinese rectifier tube with NOS, but the US- and European-made NOS rectifiers were generally around $150.

I'd gladly take out a $150 mortgage.

What are you, the Figure of Speech Police?