Vox Buckingham V112 rebuild (was Vox Buckingham questions)

[R.G.]

Reverb tank specs are confusing, I agree.
The transformer driven nature of this doesn't help you much. The UK Vox 700 series amps have a transformer drive, but it's for a piezoelectric tank, and the transformer steps UP to a high voltage band low current.
You mention the amp is on its way. When it gets there, you can measure the DC resistance of the input and output coils and pick the available impedance that matches the DC resistance most closely. That will get you the closest rated impedance. The last time I touched Accutronics and Beltone they listed the DC resistances too.
I ran into an issue with Accutronics in about 2005-2006. I was picking a tank for the Workhorse amps, and the natural choice from Accutronics just didn't sound good. I found out that the damping material for the coils/springs in the tank that had been used since antiquity had become simply unavailable. They subbed material, and the sound changed. We used Beltone. It is possible, in fact probable, that they have solved this by now, but it was my deepest dive into reverb tanks.

[seveneves]

You mention the amp is on its way. When it gets there, you can measure the DC resistance of the input and output coils and pick the available impedance that matches the DC resistance most closely. That will get you the closest rated impedance. The last time I touched Accutronics and Beltone they listed the DC resistances too.

Unfortunately, there is no reverb tank included with the amp so I have nothing I can measure.

[R.G.]

I think one of my Viscounts or my Buckingham has the original tank. I'll go out to the garage and measure. These were beaters when I got them, so maybe if they all vote the same way it will tell us.
I started updating the early drafts of the repair supplement.

I >> HATE IT << when old Vox gear is tossed into the dumpster.

[seveneves]

I think one of my Viscounts or my Buckingham has the original tank. I'll go out to the garage and measure. These were beaters when I got them, so maybe if they all vote the same way it will tell us.

Cool. Thank you. It would be good to know if these are the earlier transformer driven reverb amps or not.

I >> HATE IT << when old Vox gear is tossed into the dumpster.

Agree on dumping of old Vox gear. Almost as annoying as people robbing Thomas Organ Voxes of Celestion silver alnico speakers, chrome knobs and reverb tanks...

[R.G.]

Yeah. I paid for a run of machined chromed knobs a couple of years back. They're almost gone, and I'm faced with whether to order more or not. The machining is trivial, but even the most trivial machined part carries a huge setup fee, and USA law makes chroming just about impossible to do. Ebay sellers will sell original knobs in questionable condition for about $50-60. I'm looking for a supplier to make several hundred for a low enough price to sell new shiny repros for under about $40 each. Haven't found one yet. I may have to just give up on this. I don't really have several thousand dollars to fund the effort again.

[seveneves]

Yeah. I paid for a run of machined chromed knobs a couple of years back. They're almost gone, and I'm faced with whether to order more or not. The machining is trivial, but even the most trivial machined part carries a huge setup fee, and USA law makes chroming just about impossible to do. Ebay sellers will sell original knobs in questionable condition for about $50-60. I'm looking for a supplier to make several hundred for a low enough price to sell new shiny repros for under about $40 each. Haven't found one yet. I may have to just give up on this. I don't really have several thousand dollars to fund the effort again.

I see that you have them up on eBay (actually, your associate Jim?).

Sadly, I understand all of what you're saying, from setup fee(s) to chroming costs nowadays (can't be dumping byproducts of the process down the river... ). Unfortunately, it all comes with a cost. BTW, I'm not sure if all those asking $50-60 for a knob actually get what they're asking for, though? Your knobs up on eBay come in at a skosh over $20 (including shipping) which is actually a relative bargain! I just purchased some originals for $20 each to replace those that are missing on my amp.

[R.G.]

Yeah. That started out as me not being able to get decent knobs for my Vox amps, and being amazed at how difficult it was. I actually made that run to get me some new looking knobs, and bought a minimum run. I sold the rest to recoup my up front costs. It's a rough way to get knobs.

[seveneves]

It's a rough way to get knobs.

Indeed, that's love right there: been there, done that!

[R.G.]

Quick question - is this thing supposed to be working when you get it, or is it sold as "honest, it worked the last time I turned it on fifteen years ago"?

I'm pondering some of the additional stuff to go into the new repair supplement, and how I approach it. The first line of attack is different if a working unit has slowly degraded versus a completely unknown unit being turned on after a long time. Turning on an unused one starts with "get the power supply running safely and in good order" versus putting in all new caps and trying it out. I'm also using the original draft of the repair supplement for the V114 Beatle as the basis and removing things the Buckingham doesn't have.

I always figured that a V114 Beatle would come along before a Buckingham.

[seveneves]

Quick question - is this thing supposed to be working when you get it, or is it sold as "honest, it worked the last time I turned it on fifteen years ago"?

My assumption is that it's neither the former or (frankly) the latter. Let me explain.

FWIW, the seller is presumably somewhat well-known in Vox circles, having gone by the unofficial moniker "Dr. Vox"...

This was part of his leftovers and although he didn't say it, I believe he pieced this together. If I understood correctly, the preamp and the cabinet are original, likely "born together", which is what appealed to me (as you know, the early Thomas Organ Voxes have plywood cabinets). I'm not sure if the power amp was "born" with them (i.e., part of the very same preamp and cabinet). There's a good chance that it could have been. But at least it's a Buckingham (I guess it could also be a Viscount?) power amp.

Actually, he offered me the choice of a Buckingham power amp or a Beatle power amp. Thinking about it, I wonder if I should have gone for the latter? I opted to avoid the Beatle power amp as it seems to operate right on the edge of failure historically, more so than the Buck from what I gathered. Although, now that I'm learning about it, I guess if I were to maintain an 8-ohm speaker load with a Beatle power amp, it probably would have been fine: this amp likely will be a studio-queen only, with maybe the very occasional gig. However, if wanted it to get into 60-watt territory (a la Royal Guardsman with a 4-ohm load), I can't do that with the Buck power amp, it'd likely die.

The pics of the power amp, pre amp and cab he sent me (apart from missing knobs and a reverb tank) looked good (i.e., non-futzed with) so I wasn't particularly worried about whether the Buck power section was born with the rest of the amp. Ultimately, I just want a presentable, (eventually) working "big head" Thomas Organ Vox amp. FWIW, I had a high-ticket deal I did with him last year and he gave me a very fair deal on this Buck, which is the only way I could have gotten into one. At the very least, it's got a story/pedigree (i.e., former "Dr. Vox" amp ). And have you seen the prices recently (or at least what people are asking for them) for used "big head" Thomas Organ Voxes? Which is good I guess as it keeps people from tossing them into the dumpster.

I'm pondering some of the additional stuff to go into the new repair supplement, and how I approach it. The first line of attack is different if a working unit has slowly degraded versus a completely unknown unit being turned on after a long time.

Safer to assume the later with this particular amp, IMO.

Turning on an unused one starts with "get the power supply running safely and in good order" versus putting in all new caps and trying it out.

Seems reasonable.

I always figured that a V114 Beatle would come along before a Buckingham.

I'm curious about this statement. Are you saying V112s are rarer than V114s? I kinda thought the opposite, given the high price of the Super/Beatle when new.

[R.G.]

It wasn't a highly reasoned belief. In my youth, there were lots of Beatles and Guardsmans used. I never saw a Buckingham until much later.

My Buckingham has a replacement tank, but both my Viscounts have original tanks. They're Gibbs tanks, and both of them measure about 27 ohms on the "input" coil, 175 ohms on the "output" coil. That would make 150-200 ohms impedance on the input and 1.8K to 2.2K on the output a reasonable guess.

[seveneves]

My Buckingham has a replacement tank, but both my Viscounts have original tanks. They're Gibbs tanks, and both of them measure about 27 ohms on the "input" coil, 175 ohms on the "output" coil. That would make 150-200 ohms impedance on the input and 1.8K to 2.2K on the output a reasonable guess.

Thanks a lot, R.G. Very much appreciated.

Just to confirm, the Viscounts are V15, V115, V1151 or V1152 (i.e., they have a transformer driving the tank)?

[R.G.]

Just to confirm, the Viscounts are V15, V115, V1151 or V1152 (i.e., they have a transformer driving the tank)?

Viscounts are V15, V115, V1151 and V1154. They didn't have a V1152 to the best of my knowledge.

I'll go check my documentation, but I believe all the Thomas Vox big head amps had reverb transformers up to the last generation, the V1143, V1133, V1123 and V1154.

Back in a bit.

[seveneves]

Just to confirm, the Viscounts are V15, V115, V1151 or V1152 (i.e., they have a transformer driving the tank)?

Viscounts are V15, V115, V1151 and V1154. They didn't have a V1152 to the best of my knowledge.

I'll go check my documentation, but I believe all the Thomas Vox big head amps had reverb transformers up to the last generation, the V1143, V1133, V1123 and V1154.

OK. I guess I was asking about your amps you took the readings of the reverb tanks from. I presume your Viscounts had reverb transformers.

[R.G.]

OK. I guess I was asking about your amps you took the readings of the reverb tanks from. I presume your Viscounts had reverb transformers.

I misunderstood your question. Yes, they both did. I believe that they were V1151s.

You're asking questions that make me think you need the following system view tidbits.

Thomas seems to have designed the V1n amps with only tremolo and MRB as effects. I am guessing that they realized that an amp without reverb would be a non-starter in the market and added on reverb. The main PCB for all of the V1n, V11n, V11n1 and V11n2 amps was exactly the same, but with parts left off for amps like the V118 and V1181 Westminister bass amps. Any quirks introduced by leaving sections out was fixed up in the wiring harness. Reverb was added on with a baby PCB beside the main PCB. The later amps with distortion had a distortion baby board added in much the same way that reverb was added. It was only in the V11n3 and V1154 that a whole new main PCB was produced, incorporating all the effects sections. It was on this new main PCB that the reverb was converted to what is, in effect, a solid state amplifier to drive the reverb tanks. All the amps before the last generation had the add-on reverb board and a reverb drive transformer. It's reasonable to assume that all of the reverb transformers were identical, but -

Wait a minute. I can figure this out. Thomas had unique part numbers for all of its parts, even things as pedestrian as, say, a 1k resistor. If the reverb transformers were all the same, it will be a common part number for all the amps. All I need to do is check every amp data sheet to see if they use Thomas part number 80-5056-1, which is what the V12/V112 parts list says.

The search will take a while.