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Old 30th May 2009, 04:56 PM   #1
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Default Newcomb el84 amp

hello people,

with little knowledge i thought i'd throw this link up to a photo i took of the schematic to an old pseudo-pa my father gave me. I removed the turntable portion of the funbox and use the inputs for amplifying my computer music and my JVC QL-F4 turntable. As you can see from the schematic, i have freed up a 115 volt power source by removing the turntable.

Newcomb TR-1640M is the make/model. It came with a matching pair of speakers which i also love, it's a very rugged little unit with a sort of wooden suitcase cabinet design.

I have 2 requests/questions:

1. I realize that this is a mono amp, but does anyone tell what the class and output wattage would be for an amplifier of this design?

2. (this one is more fun) suggestions for use that freed up 115 volt power source?

I really like this thing, I have always wanted some tube gear and it is fortuitous that it came to me; being the only piece of tube equipment that i can afford to own at the moment (free!)

below is a link to some photos of the schematic. I can provide more photos of the unit if needed.

http://www.flickr.com/photos/35114660@N02/

Thanks for any input my DIY audio friends!

Regards,
Brian
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Old 30th May 2009, 05:19 PM   #2
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Yours is push-pull, i've only seen single ended versions (i have a single EL84SE here). Can you post a photo?

It is topologically the same as a Dynaco SCA35. If you just use the Aux input you can pull the 12AX7 (phono preamp) and the 12AV5 (mic pre) and reduce the load on the power transformer a bit,

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Old 30th May 2009, 08:47 PM   #3
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He mentioned using a JVC turntable, but the 12AV5 could still be removed for less transformer load.


I think you could just pull the tube , but IMO you would be better served by removing all the associated wiring , too.



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Old 31st May 2009, 11:05 AM   #4
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Default thanks

i've been using the internal phono input for the turntable, and using "mike 2" for the computer. Is the recommendation that i pull out some of the preamp tubes?
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Old 31st May 2009, 11:05 AM   #5
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Default added some more photos

click the link to flickr in my original post to see the schmatic and some new photos
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Old 31st May 2009, 03:14 PM   #6
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Default Re: thanks

Quote:
Originally posted by Element138
i've been using the internal phono input for the turntable, and using "mike 2" for the computer. Is the recommendation that i pull out some of the preamp tubes?
No, I wouldn't do that as it would change the operating voltages of some of the remaining stages. I'd leave it as is. You're basically using it in a manner close to what was originally intended.

Edit: I'm not at all sure the phono eq is correct, the schematic is pretty hard to make out. I would probably use an external phono pre-amp or modify the existing circuit for proper RIAA. The unused mic stage will contribute no noise as long as its gain control is turned down all the way.
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Old 31st May 2009, 04:25 PM   #7
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Oxford speakers... that kit is in nice condition

dave
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Old 31st May 2009, 06:34 PM   #8
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Sweet ! That gear looks like new !
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Old 31st May 2009, 08:39 PM   #9
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PS to anyone looking at the pictures, click above the photo the icon named "all sizes" this will expand the resolution of the schematics to a more readable level
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Old 31st May 2009, 08:39 PM   #10
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i'd be elated if i could find another kit identical to this, set them as mono blocs in a sense. it'd be nice
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