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Old 29th Jan 2012, 1:19 pm   #1
Heatercathodeshort
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Default GEC BCS2225 amplifier. Skip find.

I pulled this off a skip this morning. It was on top of a pile of builders rubbish and is incredibly heavy. The case is rusty but the grey painted chassis is in incredibly good condition. It would make a nice restoration project to use with my 78 disco at the steam shows. The gold labels on the chassis show that the original KT66 output valves have been replaced with a pair of 6V6's. I have a few good used KT's so no problem there. The model number is BCS 2225 '20 watt De-Luxe amplifier' and I cannot find any information on it. The valve line up is: D63 [bias rect?] KTZ63 KTZ63 H63 KTZ63 KT66 KT66 U52. Can anyone help with any service data? By the look of the components I would say it dates from around 1938/39. The mains and output transformers are massive. Regards, John.
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Old 29th Jan 2012, 1:39 pm   #2
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Default Re: GEC BCS2225 amplifier. Skip find.

John,

You must tell me which skip you use !

Looks like you could have a bit of fun with that.

TYJ
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Old 29th Jan 2012, 2:00 pm   #3
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Default Re: GEC BCS2225 amplifier. Skip find.

Tremendous find. I would guess it is a factory PA amplifier. You can just imagine a factory full of munitions workers listening to Music While You Work from it.

6L6s should be OK as output valves.
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Old 29th Jan 2012, 2:20 pm   #4
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Default Re: GEC BCS2225 amplifier. Skip find.

I thought just that Paul. Looks like a nice job. Gram, Mic and Radio inputs and full bass and treble controls. I have some good KT66's but a larger number of 6L6's so when I get round to giving it a rebuild I will probably test it with the original 6V6's.They are Mullard 'Amerty' from WW2 era and look exactly the same as the Brimar type. Something else to place in line for workshop attention. Will have to find some data on it, must be available somewhere. It's standard amplifier practise but nice to have the original data. One of the KTZ63's is in fact a KTW63, my mistake. John.
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Old 29th Jan 2012, 4:36 pm   #5
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Default Re: GEC BCS2225 amplifier. Skip find.

If it's ex factory / PA it may have 100V line output rather than 3/7.5/15 ohm.

For a 78s disco, a suitable ratio mains transformer would sort that OK
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Old 29th Jan 2012, 5:06 pm   #6
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Default Re: GEC BCS2225 amplifier. Skip find.

Hello Chris,
Just checked the sockets on the back. We have 500 0hm [line out possibly]
5 ohm 15 ohm 25 ohm 75 ohm so should just about cover anything thrown at me! I have checked the transformer and it reads OK on both primary and secondary so there is a good chance it will be a straightforward repair but not for the immediate future. John.
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Old 29th Jan 2012, 5:48 pm   #7
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Smile Re: GEC BCS2225 amplifier. Skip find.

Hi,
That's a nice amp. Built like the proverbial masonry outhouse by the look of it. The knobs are reminiscent of those 1920s faders they had in Broadcasting House (but smaller).
It makes me cringe when I think of the two amps I sold for peanuts because I didn't realise the value of the KT66s & 88s lurking within. The amps were bought by "audiophools" who simply wanted them for the valves and dumped the rest. I've got sore shins from kicking myself ever since.
One was a Pamphonic that came from our local footy ground and I used it for our church youth club disco. The other was a Tannoy mains & battery job with odd four pin input sockets.
Cheers, Pete
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Old 29th Jan 2012, 6:34 pm   #8
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Default Re: GEC BCS2225 amplifier. Skip find.

An amazing find! I shudder to think how much stuff like this gets dumped nearly every day. Knowing you, you'll replace 'that cap' and hit it with full mains......!


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Old 29th Jan 2012, 7:00 pm   #9
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Default Re: GEC BCS2225 amplifier. Skip find.

Yup.... 500ohm is 100V at 20W. Looks like it's got a full house choice there.

Re Sideband: Better make it those caps
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Old 29th Jan 2012, 7:18 pm   #10
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Default Re: GEC BCS2225 amplifier. Skip find.

...indeed! Push-pull...!



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Old 29th Jan 2012, 7:51 pm   #11
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Default Re: GEC BCS2225 amplifier. Skip find.

Hi All,

Great skip find.

I may be totally wrong, but from memory some GEC amplifiers were made by Leak using the early Leak type 15 circuit, this was prior to the TL12.1.

Terry.
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Old 29th Jan 2012, 8:23 pm   #12
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Default Re: GEC BCS2225 amplifier. Skip find.

What a great find, should be a nice amp when restored, shame the KT66's had been replaced.

Mark
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Old 30th Jan 2012, 2:34 pm   #13
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Default Re: GEC BCS2225 amplifier. Skip find.

It will require some care when first running up. I will replace all waxies and make all the usual checks. If I am right about the D63 providing bias, extra care will be taken to make sure the bias voltage is indeed present. This might have led to the destruction of the original KT66's, maybe during the war and the emergency replacement 6V6's soldiered on at more than sufficient volume. You can only guess but they seem to have sat there for many years.
It is definitely GEC manufacture of the period with the same mains input connector as used on the 1938 television receiver of the same make. A huge block capacitor something like 7+7+7+7+7uf will require re stuffing but after having tackled numerous Visconol caps from tellies I don't think this will present a problem for me. [Where have I heard that one before..]
Will have a go at it when time permits. Regards, John.
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