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Re: Hey Sidegetter, check this out!

Sidegetter, I have had two of thes amps over the years and I use one to drive my 2-12" subwoofer. The 8005 tubes seem to last a long time, like forever in this amp. The 8005 is designed for transmitter use with 1500 volts and key down or full load CCS, continuous comercial service. In the MI200 the tubes are run at 850 volts full power and 900 V. at idle. They are loafing. I have picked up a number of these on ebay as they show up at all different prices. I picked up a pair of NOS for $65.00 last year.
The MI200 has had different versions and I prefer the later 6 rectifier units. The earlier ones are OK though. The output transformer is a 60 lb. monster. It is important to have good caps in the power supply and you can use the 100/100 mfd 500 volt units that are used in the MC275. Just tie the two sides together. I checked with Sydney-C and he said this is OK. The caps are 'stair stepped' in 300 volt steps. I changed all of the single caps to orange drops and they work fine.
Be very careful around the amp as the high voltage and current can be very painfull if not life threatening. The 5931 Jan rectifiers are a good sub for the 5U4s. I have found the amp to be very stable. When the amp is on, the meter reads combined bias, 90 milli ampears and if it is off you simply turn the switch to the right or left and adjust the gain pot for each tube on the front pannel. The meter reads 400 MA. at 200 watts out.
I mounted my 200 in a 19' cabinet with large castors.On the rear I use another 19" panel which holds a whisper fan for the outputs and bannana conections, and a gold RCA jack for the input. If you send me your email I will send some photos.
The sound of this amp is awsome and you will need at least 500 or more solid state watts to duplicate the same percieved SPL. The deep bass control and extension are unrivaled. The major drawbacks are a lot of heat (those six rectifiers) and your AC bill. I run mine all the time, 8 or more hours a day and the electric bill shows it!
Make sure you obtain a proper schematic for the version you have. The voltages on your unit should be very close to the schematic if everything is working properly. If not they will need service. If you are going to run them make sure they are right.
These amps were used by to run the first cutting heads used to make stereo records in the 50s. The sound of the 200s is part of the majic on these early recordings.
It would be great to make a modern version of this amp with a solid state power supply but the lawyers would probably have a fit over the
high voltages!
Ron-C



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