Grampian valve PA amplifier valuation

[The Finisher]

Can anyone give me any idea of the potential value of this amplifier.

[Techman]

Just put it on an auction site and let the bidders decide, unless you want it to go to a 'good home', where selling it on here would then probably be the best option as you can 'vet' interested parties, but you'll obviously need some idea of a value for that. Grampian are a bit 'oddball', so not anywhere near as desirable as certain others are.

[The Finisher]

Originally Posted by Techman

Just put it on an auction site and let the bidders decide, unless you want it to go to a 'good home', where selling it on here would then probably be the best option as you can 'vet' interested parties, but you'll obviously need some idea of a value for that. Grampian are a bit 'oddball', so not anywhere near as desirable as certain others are.

Thanks for the reply, what’s the worst that could happen if I get myself the right plug ( belgin ? ) and power it up ?

[Lucien Nunes]

A shorted smoothing cap could damage the rectifier valve and mains transformer, while leaky coupling capacitors could damage the output valves and transformer. In effect, you can write-off the amp in minutes, for the sake of £10 of components or 30 mins reforming the electrolytics, even while it is showing signs of life.

Re. sale value, as Techman notes, you might get the best price on the open market but it may not survive, as equipment like this is often broken for parts by DIYers or hacked into guitar amps etc. It would also depend on whether the output transformer has a full-power low impedance secondary, as some PA amps have only 70V / 100V line outputs and cannot be connected directly to speakers without transformers. I have seen a few of these bounce when a hopeful buyer discovers it can't be adapted into one channel of their next living-room system.

[Simon Gittins]

What’s the worst that could happen - see the bottom of each page in red. More likely is damage to an expensive component because a cheap component isn't replaced. Much better to pass it on untested unless you want to keep it.


The Bulgin plugs aren't cheap and you will need to connect a speaker as valve amplifiers suffer expensive damage if they are run without one.


More advice on powering long-dormant amplifiers here:
http://www.londonsound.org/Vintage%20valve%20hi-fi.htm

[Radio Wrangler]

The worst?

There are one or two small, cheap capacitors in just about every valve amplifier which, if they get damp in them and go leaky, they turn the big output valves full on and take a lot too much current. This doesn't do the valves any good and risks burning out the output transformer and the power transformer.

Now the sting.... this is a very common failure in amps which have been stored. There are other capacitors of the same sort sprinkled around inside the thing, but only the one or two in that specially critical position.

The output valves and those two transformers constitute the vast majority of the financial value of that amplifier.

To someone used to these things. the most reassuring words are "It has never been plugged in since it was put into storage in 19xx"

Fear is engendered by "I plugged it in and all the valves lit up, but I don't know how to test it any further."

Grampian were a very reputable maker of well-engineered and reliable amplifiers. THey seemed to specialise in the public address market. Have a look for markings around the output terminals. If you see anything like 4 Ohms, 8 Ohms or 15 Ohms, then it was made to drive speakers directly. If you see something like '100v line' then it was made to drive a distribution system.

No, I'm afraid those capacitors don't eventually dry out and become safe. I'd just change them for modern parts before trying anything out.

With an auction, it could easily go for a surprising large amount, or for a surprisingly low amount. It all depends on who is watching. If you get two bidders each already with one and looking for a second one to complete a stereo setup, then watch those numbers climb.

David

[Edward Huggins]

Do NOT power this up. I sense you might be thinking this may be quite valuable?
Maybe fully restored it might - but do be aware that this was not really designed for Hi Fi use. Just by looking at it, this will need a lot of work and a full restoration might cost more than it is worth.....Put it up to Auction and see how it goes!

[The Finisher]

Thanks everyone, I appreciate your input, I will NOT be powering it up at all .

[PJL]

This is not in the same league as the Leak you had before. It is intended as a high power PA amp and not for hi-fi see this thread https://www.vintage-radio.net/forum/...ad.php?t=74050.

You are unlikely to get much for it here, under £100, but on an auction site anything can happen.

[The Finisher]

On eBay now