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Hi guys,
I'm new to this forum...it looks like a fun place to share stories and info!
I' just picked up a 1962 Ampeg R12R in need for some help! The amp is pretty dirty but in decent shape underneath it all so this should be a fairly easy restoration!
A little info about the amp..... non original speaker, 2x20uf filtercaps have been replaced with 4 100uf caps mounted on a PCB, trem doesn't work, tubes are microphonic, 60's fender handle, missing logo, microphonic octal preamp tubes. Original footswitch is still there, reverb works. 6v6 power tubes and a 5y3 rectifier
So far i've replaced power tubes, removed the death cap and converted to a 3 prong power cord, cleaned the pots, redid solder joints that looked sloppy, changed the small electrolytic caps and i replaced the speaker with a Mesa Boogie/ Celestion MC-90....this was supposed to be temporary until i found a suitable low wattage speaker for it, but it sounds to good and balanced, with great headroom and smooth breakup that i may just leave it!
I have ordered new preamp tubes, capacitor kit, logo and handle from fliptops.
Plate voltage is a healthy 345V. Bias goes from 40mA with the trem on to 55mA with the trem off (measured using a bias probe). The amp is cathode biased. I'm going to dig a bit deeper on this once i undo the filter cap mods and freshen up the amp....what should be the suitable bias range? Does increasing the 250ohm resistor increase the bias current or vice versa?
Thanks, I'm looking forward to you replies!
G
I'm new to this forum...it looks like a fun place to share stories and info!
I' just picked up a 1962 Ampeg R12R in need for some help! The amp is pretty dirty but in decent shape underneath it all so this should be a fairly easy restoration!
A little info about the amp..... non original speaker, 2x20uf filtercaps have been replaced with 4 100uf caps mounted on a PCB, trem doesn't work, tubes are microphonic, 60's fender handle, missing logo, microphonic octal preamp tubes. Original footswitch is still there, reverb works. 6v6 power tubes and a 5y3 rectifier
So far i've replaced power tubes, removed the death cap and converted to a 3 prong power cord, cleaned the pots, redid solder joints that looked sloppy, changed the small electrolytic caps and i replaced the speaker with a Mesa Boogie/ Celestion MC-90....this was supposed to be temporary until i found a suitable low wattage speaker for it, but it sounds to good and balanced, with great headroom and smooth breakup that i may just leave it!
I have ordered new preamp tubes, capacitor kit, logo and handle from fliptops.
Plate voltage is a healthy 345V. Bias goes from 40mA with the trem on to 55mA with the trem off (measured using a bias probe). The amp is cathode biased. I'm going to dig a bit deeper on this once i undo the filter cap mods and freshen up the amp....what should be the suitable bias range? Does increasing the 250ohm resistor increase the bias current or vice versa?
Thanks, I'm looking forward to you replies!
G
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