Thrift finds including a Bogen MO-100A

[cuban8]

Just wanted to share my latest finds:

The Bogen MO-100A looks really interesting...love to find another one.

The little 6BQ5 push-pull sounds amazing!

Not sure what to do with the Bogen tube PA amp and the Bogen SS Equalizer, other than part them.

 

[mashaffer]

Interesting retainers on the stereo unit. The EQ would make a nice case for a tube preamp or spectrum analyzer using indicator tubes behind the slots. PA amp could be the start of a tube mic mixer/preamp.

 

[unknown]

Cool find!
I've two of those in desperate need of refurb. They were in service at a local skating rink and not well taken care of.
Are you using 8417's as outputs?
Mike

 

[cuban8]

Interesting retainers on the stereo unit.

Those retainers are quite clever. This thing came out of a small, portable console from the 60's, and those 6bq5's are pretty tall...guess they were worried about them becoming dislodged.

 

[cuban8]

Are you using 8417's as outputs?
Mike

Yes, they have four RCA 8417's. I'm just starting to research, apparently these tubes are not cheap. I'll have to do a lot more studying before figuring out what to do with this amp.

 

[unknown]

I've found a great thread here on modding a Bogen MO200a, which appears to be a stereo version in one chassis of the 100a.
If you are interested look up 'My winter project" by Bricktop.
He modded it to use EL34's or other variants. He did a truly fantastic job with his rebuild. When I start on these (in the winter:scratch2, I hope to follow his example. I too have seen the prices on the 8417's :tears:!
Mike

 

[Tinkerbelle]

The MO-100A has good transformers across a wide frequency range. IMHO, it is well worth restoring for use with the 8417s or modifying to use EL34, 6550, KT88 etc. tubes. These come up every once in a while on the 'bay if you wanted to make up a pair for stereo. The 8417 tubes can be a little pricey but you can sometimes get them for a decent price; plus good old stock EL34s or KT88s aren't exactly inexpensive either. The manual with schematic for the MO-100A is available on line from the Bogen website: http://www.bogen.com/support/discontinued/pdfs/MO100Am.pdf

The MO-200A Bricktop thread referred to by Unknown is this one: http://www.audiokarma.org/forums/showthread.php?t=140121.

 

[cademan]

I've found a great thread here on modding a Bogen MO200a, which appears to be a stereo version in one chassis of the 100a.

The Bogen MO-200A is actually a 200 watt mono amplifier which uses two output transformers wired in parallel and eight 8417 output tubes. It can be wired for stereo if you know what to do. When wired in stereo, the MO-200A becomes two MO-100A's on one chassis.