Posted by Phil Thomas on January 8, 2014 at 11:14am
Hi Guys
Well, thanks to advice from Eric Gittins and some help from Ray at the Radio Workshop here in UK I now have my EKCO U319A up and running. Guitar plugged in and singin' like a bird. 3W of lovely blues crunch...I played my 1957 Hofner President through it and it sounds beautiful. Starting on my next CBG now...can't wait.
One thing though...there are two pin positions on the back (looks like single sockets for wander plugs) which are marked 'externals' with a diagram showing what looks like two leads going to one speaker...does this mean one live and one earth? Could I build an external cab with a small speaker mounted in a cigar box? What size? Would it improve the sound or increase volume? I am not trying to fill the Albert Hall, just a bit of home recording...any suggestions?
i'm glad the radio is working out as is - it's a real shame when these old valve amps get gutted just because someone can't spend the time to work it out.
your "EX.L.S", or external loud speaker, is just what you thought. but with that schematic there's a switch to turn off the inbuilt speaker too. yes, you can rig up another speaker, but remember that speaker load is reflected through the output transformer to the output valve, it it likes to have a load it was designed for. that means if you connect an external speaker, make it a similar impedance speaker to the one in the radio, and use that switch (sw3) to turn off the inbuilt speaker when you use the other. the switch may even be in the external jack?
the end of the world won't come about if you muck around with this, but best results will be had by sticking to what the output tube likes best.
cheers
e
Phil Thomas > eric gittinsJanuary 13, 2014 at 6:53am
Replies
hey phil, thanks for the thanks!
i'm glad the radio is working out as is - it's a real shame when these old valve amps get gutted just because someone can't spend the time to work it out.
your "EX.L.S", or external loud speaker, is just what you thought. but with that schematic there's a switch to turn off the inbuilt speaker too. yes, you can rig up another speaker, but remember that speaker load is reflected through the output transformer to the output valve, it it likes to have a load it was designed for. that means if you connect an external speaker, make it a similar impedance speaker to the one in the radio, and use that switch (sw3) to turn off the inbuilt speaker when you use the other. the switch may even be in the external jack?
the end of the world won't come about if you muck around with this, but best results will be had by sticking to what the output tube likes best.
cheers
e
I'll give it a go.
Phil
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