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Old 1st January 2011, 02:26 AM   #1
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Default fee-nix, the desktop amp

do you like the play on words?

Got an old console today. Now my normal approach has been to gut the things completely, pull the usable tubes, remove tx's and throw away the rest.

But this week at work I've felt the need for a little desktop amp that glows. So this ECL82 SE item looks like an ideal candidate for rebirth.

Currently it has MW and SW in the tuner section. That will all go - I have a good Technics tuner that will plug in to provide that side.

Inputs will be needed for the computer and maybe (later on) an i-pod dock.

The chassis will stay as it is (although I may clean it!!). Obviously it needs a full re-capping, and I'll probably LED bias the triode sections and LM3x7 bias the pentodes. The cute-sy opt's are 4ohm output, so lots of speaker options to consider too...

I'm thinking a nice oiled timber box with a mesh grill front and rear - a cross between a Tivoli radio and a Marshall amp.

Anything I've missed considering?
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Old 1st January 2011, 03:09 AM   #2
taj is offline taj
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Looks like a fun project.

Those heavy tuner flywheels (sans the big pulley) add a really classy 'feel' to a stepped attenuator. I used one as front panel bearing/shaft, so I could mount the attenuator at the inside/back near the input circuit, with an extension shaft rigged between the 2. Worked beautifully with a big volume knob.

..Todd
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Old 1st January 2011, 03:58 AM   #3
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thanks taj - nice hint on the flywheel too - I kept it for later uses...

I'm wondering about trying e-linear here as the little opts have a u/l tap - any thoughts anyone?
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Old 1st January 2011, 11:52 AM   #4
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Nice find! As for the play on words, I finally got it after a minute or so. They say the mind's the first thing to go...

I have a thing for old console amps too. I'm not sure if it's because they appeal to my urge for instant gratification, or because playing with one takes me back to my youth (I "restored" - read butchered - lots of old tube gear as a kid).

Here in the states the old Magnavox stuff in particular is nice, mainly since the amps are usually separate from the tuner/phono sections.

I've recently run across an old Telefunken Delmonico console that's beyond restoration. I was hoping for a pair of EL84's under the hood, but alas - it's a pair o' 6GW8's...
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Old 1st January 2011, 07:22 PM   #5
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Hi Mr Z. You are lucky - over here consoles (in fact everything) was local manufacture and almost invariably low power SE output. Its very rare to find a pp design except for a couple of later stand-alone hifi amps (the Fountain Gem series) that were pp using ecl and el series tubes in the finals.

There are occasional Philips Hi-Z units turning up but almost no north american stuff since our voltages are so different (we are 230VAC)
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Old 1st January 2011, 08:36 PM   #6
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Quote:
Originally Posted by aardvarkash10 View Post
...but almost no north american stuff since our voltages are so different (we are 230VAC)
From the picture, it could be any number of console amps i've pulled. I've pulled all sorts of OPTs that are cosmetically interchangable.

dave
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Old 1st January 2011, 11:04 PM   #7
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Are you sure the OPTs are UL and not hum-bucking?
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Old 2nd January 2011, 04:36 AM   #8
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gotta be a reason they attach to the anode AND g2...
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Old 2nd January 2011, 05:39 PM   #9
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On some consoles the B+ went into a tap partway in from the end. The longer end went to the plate and the shorter to the screen. The idea was for the residual hum in the PS to be cancelled in the OPT. Don't know if you could swap connections for UL or not.

e.g.

Click the image to open in full size.

I suppose you could check by disconnecting and measuring DCR from each tap to the others.
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Old 2nd January 2011, 06:04 PM   #10
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The plate resistance of the ECL82 triode section may be a tad low for e-linear, but what the hell, it's a new year . . .
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