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 Return to top of page · Post #: 1 · Written at 1:00:48 PM on 21 February 2019.
Eenymason's Gravatar
 Location: Umina Beach, NSW
 Member since 21 February 2019
 Member #: 2332
 Postcount: 1

Hi forum members.

I'm a guitar player from the Central Coast, NSW, and recently bought a derelict 1940s Classic radiogram, mainly for the knobs for a guitar project I'm working on. The cabinet is unfortunately pretty dishevelled, though reasonably solid structurally. This is the model with the glass sliding doors down below, and mirrored cocktail compartment, and a single speaker in the right hand side, under the volume/tone/radio controls. I'm going to part it out, and list usable components in the for sale/wanted forum.

So, my bonus it would appear, is the amp itself, which appears to be a great basis for a Fender Tweed 5E3 type guitar amp. It has 6V6 power tubes, and a 5Y3 rectifier tube, which is the exact format as used in Fender amps of the 50s. This is understandable, as Leo Fender was a radio/TV technician before he started making guitars/amps.

Is anyone here experienced with this type of conversion, or know of anybody (particularly in the NSW Central Coast region), that would be familiar with the process? I'm happy to pay appropriately for a sweet little guitar amp around 15 watts, using components from this Classic radiogram amplifier. I realise it'd realistically mean a complete rebuild, utilising usable parts from here, and replacing old clapped out parts, but figure the output and power transformers should be worth re-using at least...

I realise the aim of this kind of site, and it's contributors is to renew/restore old radios, but it seems to me this one is pretty much for parts only.

Regards, Ian


 
 Return to top of page · Post #: 2 · Written at 1:10:10 PM on 21 February 2019.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5262

Are you referring to destroying original radios to make them into practice amps? If so, then you won't find many fellow travellers on here. Most members here are about restoring and preserving original radios.


 
 Return to top of page · Post #: 3 · Written at 1:24:46 PM on 21 February 2019.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 1043

From what you have described it appears you have a Classic No. 24, of which I believe has a CA chassis.


 
 Return to top of page · Post #: 4 · Written at 4:27:08 AM on 23 February 2019.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 570

Hi Ian!!

Welcome to vintage radio!
Those banging noises you can hear are the mines blowing up as you stroll through vintage radio land!
Touchy subject there...………………….

Having made a few guitar amps and still trying to play bass after 50 years of trying i'm probably just about fit to comment:

No the radio wont be much chop as a guitar amp, the output tranny wont be up to it and neither will the power supply.

It may have a couple of 6V6 in it but they are just radio output valves.

You would be better off doing two things.
1/ restore the radio as a radio, great project.

2/ make a valve amp for the hell of it and yes , use 6V6 if you want to, although I preferred to use 6CA7's.

Nowadays I would make a hybrid with 12au7's in the preamp and any old car amplifier type transistors in the output.
That way you don't have to wind a pesky output tranny but do need a high voltage tranny for the valves and a low voltage tranny for the trannys!
See the amp I made in "Special projects" for my Bass guitar.

If you really want to use output valves you can buy a fender look alike tranny from ebay, use a husky power transformer intended for valves from ebay put in a big rectifier like a 5AS4, drive a couple of 6V6 so you get a wopping 10 watts.

The big problem is you need an efficient bunch of 105db speakers in an open back cabinet to get much noise with 10 watts...………...That would be a good project to make a Fender look alike amp in a Fender look alike cabinet...……………..


Don't look at me though i'm done with making guitar amps!
Watch out for those mines!
Fred.


 
 Return to top of page · Post #: 5 · Written at 12:44:08 PM on 23 February 2019.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1074

The trouble with valves is their inefficiency. Your 10 watts (wow) will waste about 50 watts in heat. Transistors will be much kinder on your electricity bill, and 100 watts of audio is not a problem.

Valves though make for a much more fun project, no need for printed circuit boards and so on.

If you use a 5AS4, there's 10 watts gone right there, just to heat the filament. The 5Y3 uses 5 watts for heating, but of course it only delivers half the output power. Fortunately they are plug-compatible, assuming the transformer can take it.

You'd probably need a preamplifier valve, such as a 12AX7, to drive the 6V6's properly.

Good luck with your project !


 
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