240VAC Amp?

[Thatch]

I seem to have stumbled across a very interesting amp that might be wonderful for guitar but am not qite sure what to do about it. It has Bell Labs steel, is a PP 6550 with a 6V6 driving them and has other amplifier input tubes and a pair of 5V4 GT rectifiers.
I managed to get a schematic of it and it is a great design, was built to power the big horns in bell towers and is a Maas Rowe Carrillons from the early 60s. It was made to make the bell sounds for churches etc. It could be used if anybody uses 240 but not modded to run on 120. The first stage is a 240 transformer as is the second, has a big out put, but there just is no way to change this from 240VAC (230 really because of the age) to 120VAC.
Does anybody in the US use 240VAC tube gear?
This is a great amp as one would expect, it cost more than a new car when it was new, is heavy as hell but I don't know what to do with it. Tubes are long gone, except the eye tube in the chassis. It is better made than anything I have ever seen out of a Hammond or Conn, or Lowry Organ, but unless you have a dryer plug where you play????
So does anybody use 240VAC tube gear? Be a shame to toss this, but I am not going to buy a step up transformer of the size it would take to run this and I don't have a 240V Variac to form caps, so rebuilding it would be a waste of time.
A pair of these would have audiophool written all over them, if they go up to 20Khz. My bet it doesn't go to 10 because anything that high isn't going to be heard for a mile in every direction around it and this was made to drive large, low Hz compression drivers with big metal horns to reproduce bell tones like a cathedral would make with real bronze bells, or the tubular bells that guys would wack with cloth covered clubs.
My guess is it would make a wicked bass guitar head, but back to the problem, who uses 240VAC for playing bass? England yes, USA, no way.
Suggestions? Seems to be a shame to tear apart a rare amp for a few usable parts and a chassis. This is all Octals, 10 of them and 5 control knobs, ivory chicken heads, has the name cut out of chrome plated sheet metal over black and an eye tube on the front face. Chassis is a WE gray, and the steel is as good as WE if it came out of Bell Labs, it is all the same stuff.

Thatch

[selloutrr]

Am I missing something? how much amperage is it actually drawing?
Why not run a step up - step down transformer and take it from 120 at the wall to 240 for the amp? They sell them in chassis mount and stand alone models.

Large format audio consoles (studio) SSL, NEVE, API, CALREC, TRIDENT, all sound best when run at europeaon voltages (210-240v)

your house should have a 220-240 volt circuit for the AC or oven. if you wanted to test out the amp.

[Thatch]

You can't just plug in a 50 year old piece of gear without warming it up on a variac. Well you can, but if it isn't ruined before chances are any caps not shot already will be after, and the ones you want the most will be the 1st to go, meaning the power supply filter caps. I am not a musician but nobody likes permanent loud hums in any of the their gear.
You might get away with doing it to a sand amp, but high voltage caps need to be carefully reformed and while you do it with the power tubes pulled you can check the pins that are supposed to be hot and make sure that electricity is getting every where it is supposed to.
I have never warmed up a piece of 230V gear so I guess you start at 40 volts and bump it up 10 volts per hour or more until you reach 200 and leave it there 12 to 24 hours, then you can unplug it, put in the power tubes, connect a speaker and turn it on. The general rules about vintage gear should be the same no matter what voltage they start out at.
Thatch

There are 2 3 amp fuses, so I guess at least 3 amp draw, probably more because there is a fuse on both the power transformers, they will probably really pull the amps if you slap some KT-88s in there and try to blow the roof off with some Altec 421s
Thatch

[Phil_S]

Is something like this not appropriate for step up voltage? It almost seem to be too cheap to be true.

http://www.amazon.com/Seven-Star-Voltag ... B0012YJV3K

OK, then, here's a 300W model:
http://www.amazon.com/Seven-Star-Voltag ... B000AY3HD8

They seem inexpensive enough.

Not clear if you have a variac. You can always use a dim bulb limiter and increase the bulb wattage. Poor man's variac.

[selloutrr]

you can start at zero and bring it up 5-10 volts ever couple minutes to make it easy every 5min. It's really not that important all you are doing is preventing the sudden shock of all the voltage rushing the cap. You can just slowly turn the dial until you get to the proper voltage slowly turning as you count to 20. If you meter the amperage as you bring the voltage up you will be able to see if the amp is stable or has a problem that would cause damage if you continued to power up the circuit.

[T Wilcox]

Correct me if I am wrong but that amp requires 240vac Euro style
1 hot 240vac
1 neutral
1 ground if there is one

The 240 in your home ( Dallas )
2 hots both opposite phase 120vac each
1 neutral
1 ground

Todd

[selloutrr]

If you want to work you will need a step up transformer. I'd take it to a tech or call a local gear rental house and rent one. Or scrap the amp or sell it on eBay to someone in Europe. Your other option would be contacting someone with a large format recording console but you would still want a variac. Call a tech.

[paulster]

Correct me if I am wrong but that amp requires 240vac Euro style
1 hot 240vac
1 neutral
1 ground if there is one

The 240 in your home ( Dallas )
2 hots both opposite phase 120vac each
1 neutral
1 ground

The two 120V hots are equivalent to the live and neutral except that it's balanced symmetrically around ground, rather than always having the neutral side at ground potential. This is fine, provided there aren't any death caps or other dodgy wiring practices used in the amp and is the 240V equivalent of the balanced power that some studios use to get quieter mains.

I use 240V step-up transformers for some of the gear I moved across the pond with me and these actually give balanced power out.

[jestaudio]

Correct me if I am wrong but that amp requires 240vac Euro style
1 hot 240vac
1 neutral
1 ground if there is one

The 240 in your home ( Dallas )
2 hots both opposite phase 120vac each
1 neutral
1 ground

Todd

Use a step up transformer to be on the safe side, uk and harmonized euoropean spec equipement runs at a 230v +/- 6% at 50 hertz, not sure of your specs over the pond but the tolerances could be a fair bit different.

[paulster]

Use a step up transformer to be on the safe side, uk and harmonized euoropean spec equipement runs at a 230v +/- 6% at 50 hertz, not sure of your specs over the pond but the tolerances could be a fair bit different.

The UK still uses 240V despite the 'harmonised' European voltages and certain other European countries still use 220V. Germany is one of the few that actually use 230V seemingly! My place in London regularly approaches 250V when the grid is quiet.

The US 240V circuits will be no different to using a step-up transformer. In the US you have a split-phase 240V circuit to get your two 120V phases and the air-conditioner, range and dryer outlets simply give you access to the full 240V that comes into the house. A step-up transformer is going to be precisely 1:2 turns ratio so if you put 120V in you'll get 240V out. They aren't going to do a funny ratio to go from 120V to 230V. I have first-hand experience of this because I have about a dozen different ones in my possession from different manufacturers so I can run different gear that I've taken from the UK to the US with me.

The only possible advantage of a step-up transformer would be isolation, but most are wired as auto-transformers anyway so you don't even get this.

The US, despite what you'd believe, is set up for both 120V and 240V appliances. Take advantage of what's already provided if it's practical.

[jestaudio]

Use a step up transformer to be on the safe side, uk and harmonized euoropean spec equipement runs at a 230v +/- 6% at 50 hertz, not sure of your specs over the pond but the tolerances could be a fair bit different.

The UK still uses 240V despite the 'harmonised' European voltages and certain other European countries still use 220V. Germany is one of the few that actually use 230V seemingly! My place in London regularly approaches 250V when the grid is quiet.

The US 240V circuits will be no different to using a step-up transformer. In the US you have a split-phase 240V circuit to get your two 120V phases and the air-conditioner, range and dryer outlets simply give you access to the full 240V that comes into the house. A step-up transformer is going to be precisely 1:2 turns ratio so if you put 120V in you'll get 240V out. They aren't going to do a funny ratio to go from 120V to 230V. I have first-hand experience of this because I have about a dozen different ones in my possession from different manufacturers so I can run different gear that I've taken from the UK to the US with me.

The only possible advantage of a step-up transformer would be isolation, but most are wired as auto-transformers anyway so you don't even get this.

The US, despite what you'd believe, is set up for both 120V and 240V appliances. Take advantage of what's already provided if it's practical.

Whats with the attitude mate, you think i dissin the us or something, sorry for trying to help someone one out, time to quit this forum if your attitude is anything to go bye
Laters dude

[paulster]

Whats with the attitude mate, you think i dissin the us or something, sorry for trying to help someone one out, time to quit this forum if your attitude is anything to go bye
Laters dude

Er, there was no attitude there. I was simply pointing out that a lot of people don't realise that US homes actually have 240V readily available, and therefore anything designed for the UK market will work happily on it (provided it doesn't mind 60Hz) since the UK still, contrary to European harmonisation, still uses 240V anyway.

If you think that's attitude then I'm sorry but you maybe need to grow a thicker skin.

[Thatch]

I decided to just leave the thing alone and try to sell it. I pulled the socket top back and sure enough it was wired as described by Paulster even though it still had the 230 plug. Go figure. I was going over the thing pretty close and found those magic words Western Electric almost hidden under the 1st power transformer so this thing will probably end up across the Pacific. I am going to try and find a weak but usable pair of 6550s, tube it up and put it on a friends auction page on that giant garage sale. So no variac, no new caps, the build is exellent and since it has 2 rectifier tubes there is no selenium rectifier, though there is a pair of big old diodes on one of the filament secondaries.
I have never seen this before but it is really smart, the 1st power transformer goes only to the rectifiers and runs the B+ for the 6550s then gets stepped on with big wire wounds for the 6SN7s and 6SJ7,6J7 and a separate double mike input has a 6SC7.
The second power transformer has nothing but filament secondaries and the one with diodes is actually neg 33V for a 6E5 that is part of the neg feedback circuit as far as I can tell.
All the inputs go through a 6V6 before hitting the grids of the 6550s. Nope, wrong there. The mikes also run up to the 6SJ7 go through a 6SN7 and then the grids of the 6550s from the other side as the 6V6. There is something called a booster input that could need a preamp to control the 6V6 and that is the boost. I am getting lost.
If this was going to be used as a head I think a guitar into the booster input, you would still have 2 inputs for microphones but can only control one at a time with the control and I would leave the chime input alone as there is a note about it needing some kind of a special control to function.
The company is still in business and they sell these massive tape players that have recording of guys playing tubular bells, or carillons. Cool amp, but I don't need it and it will take someone who really knows what they are doing to make this thing perform at its best. It is beyond me, but is really cool. I am kind of torn.
Thanks for all the replies. You guys really know your stuff. A word of advise though, always look at the plug! You wouldn't think an amp made in LA would be 230VAC, but there it is.

Thatch

[guitbanger]

It's not a 240 vac amp. It is a 110-117 volt amp. Don't let the 3 prong cord fool ya'! That cord was made to plug into a system not a wall socket. It can easily be rewired to a standard U.S. 3 conductor cord and work just fine. I know as I have about 8 Maas-Rowe carrilon amps of different wattages and purposes. The set-up you're looking at, is a series type power scheme made to connect several pieces together NOT as a stand alone power amp Follow those wires from the cord. I'm at work now so I don't have one in front of me, don't quote me on this, but one wire will go to on/off switch and one will go to the fuse, wire 117 to those and the ground to chassis and voila you should have it. I went through this several years ago when I got mine, a wtf moment for sure lol If there is not a fuse it's because it was in another piece of the system, inline. You will want to add one on the rewire. Hope that helps. The 6V6 is not to drive anything, it is used as a voltage regulator for the 6550's screen voltage (running them much lower than the plates to keep them within their limits, refer to 6550 apps in a tube data page).

[Thatch]

Thanks! The plug is a real puzzler.

How do you like the OPTs on these things? Pretty good sized, are they 20 to 20K?

Thatch