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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 22nd Feb 2021, 8:10 pm   #1
RojDW48
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Default Chapman 305

Does anyone have any info, history on this EL84, P/P stereo amp? A friend has one with no info - looks nice.
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Old 22nd Feb 2021, 10:55 pm   #2
barretter
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Default Re: Chapman 305

If you go to
www.argaudio.it
and scroll down a bit you will find an article about the repair and restoration of a Chapman 305-ma amplifier.
I may have a circuit diagram somwhere but don't hold your breath.
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Old 22nd Feb 2021, 10:57 pm   #3
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Default Re: Chapman 305

Google translate will turn the article into English for you.
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Old 23rd Feb 2021, 12:31 am   #4
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Default Re: Chapman 305

Many thanks - it does seem to be well found. Surprising there is so little to find about it.
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Old 23rd Feb 2021, 1:35 am   #5
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Default Re: Chapman 305

Some information here:

http://ukhhsoc.torrens.org/makers/Ch...Amplifier.jpeg

http://ukhhsoc.torrens.org/makers/Chapman/index.html

As best I can determine, the Chapman amplifiers were "ordinary", using standard circuits. I suppose it was the case of a tuner specialist expanding its product line. (Jason did something similar at about the same time.)

I haven't seen schematics for any of the Chapman amplifiers.


Cheers,
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Old 23rd Feb 2021, 8:15 am   #6
snowman_al
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Default Re: Chapman 305

I had one and restored it 20 odd years ago. Finally sold it in 2011. I've seen it on eBay twice since then at considerably more than I got!

Only pictures I have are the completed state. (Digital cameras were not common when I first did it up, so no before pictures.)

I will look through my notes and see what I have. I remember it is not the Mullard 5-10 design. It had Partridge transformers and was sweet sounding.

I had the matching control unit too, but sadly 'modified it' beyond saving...

Alan
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Old 23rd Feb 2021, 9:26 am   #7
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Default Re: Chapman 305

Hello,

I've one of these amplifiers, which I restored quite some time ago. Can't find the circuit, although off the top of my head its UL and the driver isn't that dissimilar to the Rogers Cadet (by chance in the background of one of the photos) and Junior, although please don't quote me on it! One thing I do remember the EL84's were slightly under run.

I can get it on the bench and take some better pictures to ascertain the exact circuit - before this I need to get the 'odd-ball' Armstrong (which has similar driver) put to bed and off the bench.

I didn't bother with the control unit as I used it with a 'pot in a box' volume control as I remember it having just enough sensitivity to use it with a CD, DAC or a phono amp with decent output.

Regards
Terry
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Old 23rd Feb 2021, 9:53 am   #8
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Default Re: Chapman 305

No notes from my rebuild.
But yes EL84 in Ultra Linear push pull and under run so only 8 watts.

From page 24 of Audio Audio, ''Chapman 305, 1959/64 ... EL84 UL PP ... output impedance 3 or 15Ω ... price 21.'' And, ''CT Chapman (Reproducers) Ltd. Chapel Lane, High Wycombe, Bucks. Then Derritron Ultrasonics from 1962.''
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Old 23rd Feb 2021, 9:54 am   #9
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Default Re: Chapman 305

I had one of these amps from 1962 - 1966. I used it with an EMI EPU100 integrated arm and cartridge ( mm ) A rare pickup. Goodmans AXIOM 400 type speakers. The whole system sounded pretty good back in the day. I recall the 305 preamp had poxy individual gain setting pots in the low level signal path and could be very noisy. Otherwise no problems.
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Old 23rd Feb 2021, 5:10 pm   #10
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Default Re: Chapman 305

I used it with an EMI EPU100 integrated arm and cartridge ( mm ) A rare pickup.

I had one of those many years back - lovely thing, but the cartridge died and I couldn't find anyone to repair it.
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