TUBE RADIO TO TUBE AMPLIFIERS

Luxman 507z Integrated Amplifier
ashar

ashar

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In this post i ll share my works with tube radios and their coversion to mono or stereo amps as we dont have any sw mw bands existing and the radios are useless and just showpieces so why not good tube amps from them

Local flea market score

IMG-20180905-WA0043.jpg

curious me..
chasis is out for inspection.

It contains BEL tubes all working fineIMG-20180905-WA0044.jpg

Radio removed,
Chasis modified to allow the tubesIMG-20180905-WA0045.jpg put to view from front panel.

Mono amp also added a inside lampIMG-20180905-WA0049.jpg

 
Hi Ashar ,

Great Job ! I have been thinking on same lines for a very long time .
Got a tube radio but could not gather support for conversion .
Also thought of making a new box after modification .
My question can we make .
1. Make it more compact and
2. Output on 8 ohms speaker thru transformer .
Ur comments pls.

Rgrds ketan
 
Thankyou for all your interest in the amp.

Its a mono amp thats how all radios are.
The plan is to have two mono amps and have the stereo effect. Like u can two monoblocks.

Yes it can be made compact like the mcintosh or even stingray just need to throw the old radio cabinet and make a good looking chasis.

Most tube radios do have a output transformer and dont need an extra to be added what looks like a big capacitor in my tube radio is a output transformer.
 
It might be a stupid question but what cleaning agent did you use. It will be mighty kind of you if you could mention the cleaning process along with some pointers (in brief or detail), as per your convenience.
 
@kbhuvi I m a biker. And petrol works everywhere for me. A good soft brush, then petrol in a squirt bottle and cotton rags.
You can also use thinner (paint reducer) , medical spirits (not recreational) .

@yogibear you are right thats the way to go. and the only hurdle is finding two identical. once u get that its just a good build away
 
Alternately, you can replicate the existing mono channel leveraging common resources within, and covert the rig into a 2-channel piece. You'd already have the chassis and valve sockets (spare ones after removing the RF valves), you can leverage the same power supply (rectifier, usually EZ80, filter capacitors, choke and power (auto) transformer. You'd need an additional set of valves (possibly EL84 and EF86), some components and an output transformer which you can salvage from any other valve radio in this range (model does not matter), hence you technically don't need to find 2 absolutely identical models after all :)
 
reubensm said:
Alternately, you can replicate the existing mono channel leveraging common resources within, and covert the rig into a 2-channel piece. You'd already have the chassis and valve sockets (spare ones after removing the RF valves), you can leverage the same power supply (rectifier, usually EZ80, filter capacitors, choke and power (auto) transformer. You'd need an additional set of valves (possibly EL84 and EF86), some components and an output transformer which you can salvage from any other valve radio in this range (model does not matter), hence you technically don't need to find 2 absolutely identical models after all :)
Click to expand...
very well thought.
I ll try to do the same
 
if one is game, there are loads of lovely output tranny pairs, from the likes of telefunken and others, that come up quite often on ebay.de

These are usually of the 3-10 watt types.

Also from experiences shared by my father during long electronics discussions, the output transformers and power transformers used in most Indian brand valve radios of those days were usually made in Delhi or Punjab and were of very basic quality, to keep costs to a minimum. These were kind of similar and interchangeable.

Personally i have found the output trannies in old guitar amps to be very good, but they are impossible to get.
Edit:
Also wanted to add, at times I have found the output transformers on Indian Philips tube radios to be slightly different from those in Murphy, Nelco, Bush, etc. The very designs of Indian Philips tube radios used to be slightly different.
 
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No need to pull out the oscillator and tuning circuit section. All these radios have PU input that takes a line level signal directly to the amp section when selected. What is necessary and critical is to renew all power supply caps, modify the rectifier section if it uses selenium rectifier and clean the volume/tone control pots with a good contact cleaner.

And for stereo, an easier option is to look for old R2Rs in the bazzar. Akai 1710 and Grundig TK46 come up quite regularly.


Regards
 
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