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Old 22nd August 2012, 06:10 PM   #1
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Default What to do with this old amp? suggestions please.

Hi everyone, i' ve bought this amp just because it was so dirt cheap.

i received it today through the mail and as quick as i could opened up the package.

i felt like an 8 year old unpacking his long awaited birthday gift. :-)

well as you can see in the photo's it's a bit dirty, some spiders lived in it and the dust is about 5millimeters thick.

the tubes are:

2x 6bq5 / el84
1x 12ax7 / ecc83
1x ecf80

now my first idea (when i bought this amp online) was to restore it, but in this shape maybe it would be better to just use harvest it for parts and build something new.

all suggestions are welcome.
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Old 22nd August 2012, 06:51 PM   #2
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The amp is mono push-pull?

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Old 22nd August 2012, 07:23 PM   #3
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yes, it is mono, 2x el84 looks like push pull to me....
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Old 22nd August 2012, 08:02 PM   #4
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It's a hazard for sure. send it to me post-paid and I wiil dispose if it properly.
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Old 22nd August 2012, 08:14 PM   #5
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Quote:
Originally Posted by brucetassin View Post
It's a hazard for sure. send it to me post-paid and I wiil dispose if it properly.
sure, if you send back a quad II or equivalent

but what would you do with the useful parts?
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Old 22nd August 2012, 08:32 PM   #6
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Quote:
Originally Posted by mrneedle View Post
but what would you do with the useful parts?
Get it working obviously? Then get another one for a stereo pair.

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Old 22nd August 2012, 08:34 PM   #7
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I'd make it into a really nice stereo preamp
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Old 23rd August 2012, 12:29 AM   #8
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Andy's point about a preamp has (IMO) a lot going for it. Notice that the filter choke is rated at 60 mA. That's not quite enough to support conversion into a stereo SE amp, but it's plenty for a preamp.

There are enough Noval sockets to support 12AX7s or 6922s in a phono section and either 12B4s or 6FQ7s in a line stage. Add a small toroidal power trafo to energize a DC heater supply for the phono section. Replace the OEM SS B+ rectifier with "noiseless" high PIV Schottky diodes. Save the O/P trafo for a guitar amp.
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Old 23rd August 2012, 05:03 AM   #9
ChrisA is offline ChrisA  United States
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Quote:
Originally Posted by mrneedle View Post
...
the tubes are:

2x 6bq5 / el84
1x 12ax7 / ecc83
1x ecf80


all suggestions are welcome.
You have everything you need there to rebuild it as a Marshall 18W amp.

Take a look at the schematic below. It is a good match it what you have
http://mhuss.com/18watt/schematics/18wattLite.gif
Seriously, if you are into vacuum tubes you should learn to play guitar.

OK if you must build a stereo amp you will need more parts starting with a pait of output transformers. With the tubes you have you could build a single ended power amp. The EL84 is not bad as a singled ended power tube if you get a good output transformer. It can produce a solid 5W of power per channel.

OK you need more than 5WPC and you don't want to learn how to play a guitar then build the 18W marshal and sell it for 20X over what you paid for this.
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Old 23rd August 2012, 07:37 PM   #10
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The iron seems to be amroh tell us the mains transformer part number.

An option would be to search another 6006 Choke use the mains transformer and get some EL84SE transformers wound by AE i heard a pair was about €80

split the supply up. from the rectifiers onwards use some 1n4007 in a half wave configuration or a EZ80

Classical ecc83 gain stage whit a self bias EL84 in class A


v4lve

Edit strip that chassis and roughen it up whit a steel brush and degrease it coat it in a layer of primer and you have yourself a nice chassis
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