Monday, 10 April 2017

Schaller Treble-Bass Boost

Not much info on this but, it's a rare West German Schaller vintage “Treble-Bass Boost” from 1968. It typically goes for over $400usd, so fairly desirable. It's a 2 transistor based booster, with a five position switch that controls the the frequencies being boosted. There's 2 treble settings, 2 bass settings, and 1 mids setting. Seems like it also gives a little bit of drive too, which is a nice addition.




6 comments:

  1. Built this but I do have a slight issue in that its way below unity. When switching on my clean signal drops to almost nothing. It is working as a dirt pedal after confirms but i reduces the signal of that also. I'm using BC550c as they seemed a reasonable replacement for the BC239c. Any ideas?

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    1. honestly i don't. i think a BC549c it a drop in replacement for the BC239c. if you've got some of those try them. i'll look over the layout when i take my next study break. not counting the volume drop, does it sound and behave like it does in the clip? cause if it doesn't i could have an error in the layout, and would give me some more direction.

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    2. I'm on a phone and no schematic to compare it to but that last transistor isn't doing much as drawn. Shouldn't the out cap connect to the collector and not the base?

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    3. damn you're good. took a look at the schematic and damn if i didn't put the output cap at the base instead of the collector.

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  2. Well spotted Ciaran. Changed that and bingo! Works like a charm now. Call it verified! Everything working as it should. Very nice indeed. Thanks again Zach for the layout.

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    1. so i moved a few things around so i didn't have to add another row or do anything major, plus gives the electrolytics plenty of breathing room.

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