for your amusement.
http://www.ebay.com/itm/180853193398
"Massive Bogen MO-200 tube amp 100W/channel stereo bandwidth 7Hz - 50K Hz nice!"I have one and converted to 6550's (coke bottle ones touch) and 12AX7's with a bias change. It can also use EL34's. Mine makes 90W into 8 Ohms on the 25V taps. So I can offer this info.
The ultimate low voltage tube modulator.. Note it will not ever, ever do 200W at 7Hz. But it will at 20Hz.
The price is laughable as evidenced by the furious bidding war. Maybe worth 1/2 that, but a phool and his money. Maybe I should polish mine up a bit and ask even more.
Model MO-200 / MO-200A
Tubes, Output Eight 8417 beam power tubes
Tubes, Driver Two 7247 dissimilar dual triodes
Frequency Response +/- 1 db, 8-50,000 Hz @ 1 watt
Power Output 200 watts, +/- 1 db, 21-50,000 Hz @5% or less THD
Input Terminations RCA style input connection; Approx. 1 volt RMS input for full output.
Output Terminations Screw Terminal Strip, Phenolic.
8 ohms
25VCT (3.125 ohms CT/0.78 ohm) use 4 ohm load
70VCT (24.5 ohms CT/6.125 ohms)
Comments:
The amplifier consists of two almost separate amplifiers sharing one power supply, each with its own output transformer and push-pull-parallel set of 8417 tubes, and a 7247 driver. The inputs to the 7247 grids and the secondaries of the output transformers are connected in parallel.
If the input sections and output wiring are separated, the impedance conversions are shown below:
Original Operation (as a single channel amplifier)
8 ohms
25VCT (3.125 ohms CT) use 4 ohm load
70VCT (24.5 ohms CT/6.125 ohms @35V)
Split Operation (as a two channel amplifier)
16 ohms
25VCT (6.25 ohms CT) use 8 ohm load - -I got 90W/channel this way.
70VCT (49 ohms CT/12.25 ohms @35V)
