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Bogen MO100a mods

M

mojoworkin3

New Member
I recently bought two Bogen MO100a amps and I am interested in updating them. Anyone have any experience with them to really improve them? They have only a 16 ohm tap, any problems converting to 6550 or EL34 tubes driving 4 or 8 ohm hi fi speakers? I understand the primary of the OPT is 1600 ohms. Looking for to ideas to update the power supply, input stage and change the 8417 tubes since they are expensive and hard to find. Any ideas for any other output tubes? I know the 8417 has high transconductance, which is why Quicksilver used this tube. Any thoughts? thanks.

Mojoworkin
 
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Do a search of Mo200a and MO100a on this site. I think it was a 200 that was beautifully refurbished and converted last year or the year before. Since the 200 is basically parallel 100's most of the work should be usable by you.
 
Bogen MO100a

Hammr7,

Thanks for the heads up. I have done some browsing and found the posts from Tinkerbell and Bricktop which is really helpful. I have two Baldwin mono blocks as well and there are some helpful mods here.

Mojoworkin3


___________________

Gear:

Amplifiers: Preamps:
Moscode 300 (2) Audio Research SP16
Moscode 600 Dyna PAS3 modded
Dyna St-70 VTA 12BH7a triode input DBX CX1 Fet preamp
Bogen MO100a mono blocks
Baldwin PPP 6L6GC mono blocks Linn Sondek LP12/rega/benz micro
DBX BX1 1 ohm stable monster
Muscial Concepts Hafler DH200 CD player
Hafler DH200 Doge 6 tube
Scott 222D Shanling CDT100 tube
Fisher 500c Speakers

Magnepan MG111 biamp elec/xover
Celestion SL6S monitors
JBL C40 Harness
JBL Dorian
 
I'm humbled fellas, thanks for the kind words.

I have a few pics of the MO100As, nothing complete yet. Circuit will be different than the MO200 cause of parts differences and balanced inputs.
 
I like the idea of balanced inputs, just for the XLR connectors sake. I hate RCAs and have considered using something else on my stuff. I sort of like the connectors that you see on scope leads (that twist and lock). I just need to make the commitment to something and go with it.
 
Ha! Great minds think alike. That would be my choice for single-ended signals over RCA any day. I bought some of these BCJ-RU panel-mount connectors a while back but haven't used them yet. Planning to put them on the preamp one day or maybe the phono stage inputs :scratch2:
 
mo100a power transformer

what do you think of the capabilities of the MO100A power transformer. i have one but have no idea what the B+ amperage rating might be. i want to use it to build myself a nice stereo tube amp
 
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