'EXPERT' Amplifier. Info needed.

[Paul Mathew]

I'm no expert, but does anyone have more info on this amp extracted from a gram? Thanks.

[Edward Huggins]

What's the valve line up - 4 x ECL86s?

[GrimJosef]

If those are ECL82s with an ECC83 under the screening can then it's got the correct audio valve line-up for a Mullard Seven Watt Stereophonic Amplifier. The rectifier looks like a GZ32 though.

Cheers,

GJ

[ms660]

I wonder if it's this outfit:

https://worldradiohistory.com/hd2/ID...t%20pickups%22

Lawrence.

[Herald1360]

In my "expert" opinion, it looks much nicer than the similar spec and role amp from the Pye G63


Though the one pictured is particularly grungy

[Paul_RK]

I've never met one, but I think it's bound to be one of the later products of E.M.Ginn, known for their remarkable acoustic gramophones and later for the "Monthly Letter" reviewing classical recordings.

https://en.wikipedia.org/wiki/E.M.G....de_Gramophones
http://www.gramophonemuseum.com/expe...producers.html

From the second link there, in its latter days 'EXPERT offered its clients a unique custom built music system to suit each customer. Components were sold separately, or combined in a unique EXPERT machine, "tuned" by David Phillips. No two machines were ever exactly the same' - so perhaps not much chance of finding any detailed information on this unit.

EDIT: Ah, now that I've taken the time to read the second article, it looks as though "Expert", driven by a Michael Ginn, was a breakaway operation locked in competition with E.M.Ginn, though "Expert" had been used by E.M.Ginn for years as a trade name for their gramophones, soundboxes etc.. Quite a thick plot, then, which might be open to a clearer explanation by someone already familiar with it!

Paul

[qualityten]

Could you post a couple more pics, on with the top covering of the transformers removed and another from below? Also, as already requested, let us know what the valve lineup is. It looks a quality item!

[Edward Huggins]

Originally Posted by Herald1360

In my "expert" opinion, it looks much nicer than the similar spec and role amp from the Pye G63


Though the one pictured is particularly grungy

This was never designed to look particularly pretty. We needed a slim chassis arrangement with under-vented cooling for the very shallow desogn of the G63 "Slimline" chest cabinet.

[Paul Mathew]

Thanks for the reply's. Pics as requested.

[Paul Mathew]

A bit confused about this fuse. The yellow wire comes from the mains tx and via the fuse to chassis. I can't remove the fuse from the bulgin sleeve. It is spring loaded with glass visible through a small hole along the length of the sleeve. Any ideas?

[Paul Mathew]

Ok, jumped the gun on that one. It's on the centre-tap of the secondary HT. Now to work out the rating .............

[qualityten]

As GJ suggests above, it's a good quality implementation of the Mullard 7W stereo circuit.

Members of this forum patiently helped me sort out the hum on my build in two threads. The more recent one may be useful to you, especially for the link to the Mullard book and circuit at the start: http://www.vintage-radio.net/forum/s...d.php?t=178047 E.g. the circuit diagram there shows the fuse rating to be 250mA.

[Paul Mathew]

Great. Thanks for that info. I see most specs are 300mA MAX for the GZ32. Looking forward to getting this up and running.

[Herald1360]

Originally Posted by Edward Huggins

This was never designed to look particularly pretty. We needed a slim chassis arrangement with under-vented cooling for the very shallow desogn of the G63 "Slimline" chest cabinet.

I'm sure the Pye G63 amp was a sensible design for its job. The Expert one was clearly aimed for different and more varied applications and would have been overkill for a dedicated stereogram application. It comes look good, though.

The G63 cabinet wasn't that shallow, about 10" ISTR. Plenty of room for an 8" speaker in each end!