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.
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?
ReplyDeletehonestly 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.
DeleteI'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?
Deletedamn 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.
DeleteWell 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.
ReplyDeleteso 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.
DeleteGreat post. Thanks for sharing, also check on video bass booster for android.
ReplyDelete