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-   -   Is this old valve amp any good ? (https://www.diyaudio.com/forums/tubes-valves/354936-valve-amp.html)

TheFinisher 23rd May 2020 10:08 AM

Is this old valve amp any good ?
 
6 Attachment(s)
Would this be of any use to someone on here ? Maybe the parts ?

Attachment 846596

Attachment 846597
Attachment 846598
Attachment 846599
Attachment 846600
Attachment 1

freddi 23rd May 2020 10:50 AM

other than the outside of its chassis - it looks first class and those blue caps aren't "terribly old". It should be a solid foundation for a nice mono setup.

Dust the transformers off, use a "rust reformer" then paint them.

Galu 23rd May 2020 11:22 AM

Looks like its based on the Mullard 5-20 circuit with an extra pre-amplification stage.

It's in need of knowledgeable renovation, particularly in terms of bringing it up to modern safety standards.

Good for 20 watts and I'm sure there's lots of 'valve heads' who would be eager to get their hands on it! :)

TheFinisher 23rd May 2020 11:31 AM

I think itís a Grampian 562a PA/guitar amp .
20 watts.

Galu 23rd May 2020 11:45 AM

Well spotted!

Definitely a Grampian, but with an extra EF86 to the usual 562a circuit.

The one shown in the link below uses 6L6 output valves.

562A Ampl/Mixer Grampian Reproducers Ltd.; Middlesex, build

Galu 23rd May 2020 11:55 AM

Below is a link which more clearly shows the standard 562A layout and valve complement for comparison.

Seems that you may have a different (and perhaps rarer) model.

Grampian 562A vintage valve PA amplifier. Free data sheet by GB Audio

TheFinisher 23rd May 2020 12:11 PM

Quote:

Originally Posted by Galu (https://www.diyaudio.com/forums/tubes-valves/354936-valve-amp-post6215724.html#post6215724)
Below is a link which more clearly shows the standard 562A layout and valve complement for comparison.

Seems that you may have a different (and perhaps rarer) model.

Grampian 562A vintage valve PA amplifier. Free data sheet by GB Audio


Thanks Galu [emoji1303]

Schmitz77 23rd May 2020 02:11 PM

And it has extra input trannie, which is excellent.
This is a classic EL34 push- pull power amp with excellent parts and crafted with real workmanship. Finished in hammered silver gray colour.

It the trannies are working, the rest could be restored and needs a new paint job. Ready to rumble for the next fifty years.
Someone has already exchanged some caps for new ones. So the pricey part is done. Check the circuit for correct voltages!

Galu 23rd May 2020 02:39 PM

The input transformer would have been included to support the use of a moving coil microphone for public address purposes.

Possibly the early Grampian MCR! MCR Microphone/PU Grampian Reproducers Ltd.; Middlesex, buil

poynton 23rd May 2020 02:48 PM

It's probably worth £200+ as is.


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