Installed 12" Speaker in Pro Jr---Now What??
A friend has asked me to make his '94 Pro Jr (Tweed version) gig worthy. I checked the tubes, replacing a microphonic 12ax7. I installed a Vox Neo-Dog (same as Celestion Century Vintage), and a larger OT to match this 16 ohm speaker. This is the only speaker which had a small enough magnet to fit, and I still had to trim the heatsink to manage it.
When I play it, it doesn't seem to have much headroom or snap. I don't have another EL84-based amp to compare it to, but compared to a Deluxe Reverb or my Rivera 30-112 (running on 6V6's as well) there is nowhere near the clean output.
The tubes are running stock fixed bias, which I think is about 14 watts per EL84----should this be adjusted?
The circuit looks like it has quite a bit of its gain dumped between stages, presumably to increase distortion (ala Soldano). Should this be revised?
The power tranny is also quite puny--is it just too much to ask of a Pro Jr?
A friend has asked me to make his '94 Pro Jr (Tweed version) gig worthy. I checked the tubes, replacing a microphonic 12ax7. I installed a Vox Neo-Dog (same as Celestion Century Vintage), and a larger OT to match this 16 ohm speaker. This is the only speaker which had a small enough magnet to fit, and I still had to trim the heatsink to manage it.
When I play it, it doesn't seem to have much headroom or snap. I don't have another EL84-based amp to compare it to, but compared to a Deluxe Reverb or my Rivera 30-112 (running on 6V6's as well) there is nowhere near the clean output.
The tubes are running stock fixed bias, which I think is about 14 watts per EL84----should this be adjusted?
The circuit looks like it has quite a bit of its gain dumped between stages, presumably to increase distortion (ala Soldano). Should this be revised?
The power tranny is also quite puny--is it just too much to ask of a Pro Jr?
Pro Jr Upgrades
I already installed the OT from a Mesa 50W amp, so it should be adequate iron. I think a DR power trans could be prohibitive unless you have a used one fairly cheap---I see you are in Geneva/Elburn, and I'm in Geneva! Email me if you have something lying around (I 'm too new to this forum to have outgoing emails).
Matthew
I already installed the OT from a Mesa 50W amp, so it should be adequate iron. I think a DR power trans could be prohibitive unless you have a used one fairly cheap---I see you are in Geneva/Elburn, and I'm in Geneva! Email me if you have something lying around (I 'm too new to this forum to have outgoing emails).
Matthew
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