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Did a search here on Plush and didn't come up with much, anyone here know about this head and possible mods for using it for guitar and Fender Rhodes piano in the studio? It has 4 channels, each with a high and low input jack, gain, treble, bass, mid range (is this different than just a mid shelf EQ?) and a switch to engage it's spring reverb for that channel. Was thinking of making each channel a bit different, at least with the EQ choices and setting it up for studio use. Pretty sure it's an exact Fender ripoff as all of their stuff was from what I've read on the net about them but what model I don't know (would help to know so I could grab the right Fender schematic for modding). It has 4 Slyvania STR387 power tubes (4 in a row on the back) and 8 RCA 12AX7/ECC83 tubes (7 in a row on the back and 1 at the front) in it plus 2 big transformers. Any info at all you could give me at this stage would be very helpful. As for speakers for it my thinking was to have different cabs to plug it into, probably a couple 2x12's closed back with different speakers in the same cabinet wired so you could just plug into one or the other or both for the max variation of tone a player might want. Any speaker suggestions? Would probably want one speaker to give me a Fender Twin sound which would be very useful for recording the Fender Rhodes I have.
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PLUSH!!
I've been reverse-engineering my '72 Congress-IV, It seems to be really close to a Twin Reverb (minus) vibrato (plus) three channels. The EQ sections are very close to what would be in the Blackface amps but mine use 100K pots for the mid control. I don't have the tone stack calculator running, but I do know this value is quite a lot higher than a Fender midrange pot or the fixed resister in most blackface amps. The only other major difference I found is the bottom resistor of the 'long-tailed pair' phase inverter. This resistor and the 820-ohm resistor in the negative feedback line make a voltage divider that sets the NFB level. I believe a Twin has a 100-ohm in this spot (820ohm over 100 ohm voltage divider), my Congress has a 1.5k here (820 over 1,500) which would be a major increase in negative feedback. Big difference in clean headroom, compression, and frequency response, great for a vocal PA amplifier (and bass guitar
) possibly not all that desirable for overdriven guitar work. Tell you the truth, when I got mine set up right and ran through a 4x12 marshall cab the damn thing drove us out of the room before the power tubes started to crunch. I'm no stranger to 100-watt tube amps, this thing is LOUD.
Lots of fun to be had modifying the tone stacks and pre-amp sections, there's 4 of 'em so go nuts. Could lead to a relatively compact rig if you're doubling on Rhodes and guitar in the same gig, as long as your pedals can get you the tone you're after.
Have Fun!
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