Pro Audio Design Forum

Thanks John! Was that a Popular Electronics or TAA schematic?

I could scratch something up this weekend if there is interest, but probably not worth it for a one off.

Particularly since we all have extra power amps laying around. I think the ratio of amp channels to speakers here is at least 5 to 1.

Just had an idea. Take this current booster circuit with a 1646 (shown below) and make it a swinging op amp by voltage bootstrapping the rails as in the MCI drawing: https://www.ka-electronics.com/images/jpg/THAT1646_Current_Boost.JPG This gives you lots of output current, the bootstrap transistors ...

I used to write a column in RE/P so have some old issues laying around. John - Thanks for posting here in this neck of the woods. I think that ad ran in '77 or '78. MCI treated it like a major breakthrough. I think it was a cartoon but everytime I saw it I thought of Little Feat's "Dancing Sho...

Note: the "swinging opamp" if it's what I think it is (common emitter transistors driven by opamp power leads) is a relatively simple way to get there. Yep - that's what it is. Pretty simple circuit with widely available parts. Wished I had an old RE/P or dB magazine with the original MCI...

I'd go with the "MCI Swinging Op Amp" using a solo 5534. You might also try an NJM2114 there. They've got almost twice the output current of a 5532. Parallel the inputs of both sections and ballast the outputs through maybe 10-47R and you should be able to get 100-120 mA. Have the summed o...

Oh, so you want 100V? I did that when I was 17:

https://www.ka-electronics.com/DC_Pream ... 261974.jpg

This one is 70 V p-p. I made it ~100 Vp-p but it was a follower since more than about 70V exceeds the range of the op amp.

Do this with a pair of 5534s for balanced output. Note that Q1 is drawn with incorrect polarity. It should be an NPN. The base-collector capacitors, C114 and C115, are also incorrect and are 680 pF in the MCI. https://www.ka-electronics.com/images/jpg/MCI_Swinging_Op_Amp.jpg Image courtesy of MCI an...

I would go the power amplifier route. I think I have an HP200 with a high level option that might do it. Do you need +30 dBu or +30 dBm? You can get +27 dBu with a 1646. You might be able to squeeze +30 out of a good one using supply voltages above the absolute max and a heatsink. :geek: I actually ...

typed /K instead /L /K for kill? That's brutal. Roger - Does your keyboard have a Windows function key? That may be it to since IIRC it's by the spacebar. I use old geniune IBM keyboards that have the "Selectric" style tactile sensation. They don't have Windows Keys so I don't know what t...