A great sounding and flexible 2-band baxandall eq booster that can get quite gritty depending how you set the internal gain trimpot. The Mid control is not actually an active mid band control, it is a passive variable resistor that changes the overall mid slope.
Note that this seem to be an earlier version, the current version got a small revision with an external gain control and fixed mids. More info on that at Blackhawk Amplifiers.
Works great! nice simple EQ. Made the trim pot external and like the extra control. Mid pot might be wired backwards? Maybe swap Mid 1 for Mid 3 to increase the slope with a clockwise turn if thats your fancy. Thanks Fuzzhead!
ReplyDeleteThats a good idea to have the boost trimpot as a panel mounted pot, I I think I will do that mod.
DeleteAs for the Mid control, yeah it is backwards but the trace is clearly connected between pin 6 and lug 1 of the Mid control so I kept it that way. But it is an easy fix to reverse the sweep....:-)
Great little EQ boost, works very well with Morgul or Valhalla.
ReplyDeleteI just notice than the volume 1 and 3 are inversed for clockwise turning. i have swap Mid 1 for Mid 3 too as Weird(er) say.
I built this and every time I turn it on my guitar sounds better. It's pretty cool. I made the trim pot an external control, but after playing it I can see why it was a trim pot. I also found that volume 1 and 3 were backwards, but I never looked back at the layout to confirm what was going on before swapping them, I just went ahead and did it. So I could have just made a mistake. Mine doesn't have a ton of gain, I'd say about 6-12db of gain depending on where the knobs are set. I'm wondering if could have made a mistake because others said their build was gritty with the gain up and mine is always clean, though I don't have any super high output or active pickups wired up.
ReplyDeleteAfter spending more time with this, I wanted to post my final thoughts. This circuit has some serious potential and sounds really good. Mid 1 for mid 3 is a good move, unless you want the mid knob to work like a "mid cut" which is certainly a viable option. But I prefer the user experience with it swapped by a significant margin. You'll probably have noise if you try to use it with a daisy chain, it needs an isolated power supply. With a good power supply it's decently quiet, but it could still use some power filtering. I use this at the beginning of the chain as an always on "tone sweetener." It sounds really good before distortion, I think it can get ice picky when placed after. It sounds dull when cutting treble but really good when boosting it a bit. The bass band is awesome.
ReplyDeleteThere's no schematic in that link, anymore.
ReplyDeleteDid someone save it?
Anders has never posted any of the Blackhawk schematics he has. I believe out of respect for the designer's wishes. A lot of the tune low/play slow/LOTR crowd don't always seem keen to show their work to the DIY circuit community. Which is totally their right, of course...
DeleteAnyway - I believe that now-dead link originally just went to a listing on Blackhawk's site where they used to be selling the fully built pedal. These days it looks like they have an updated version of the Morgul, a compressor/sustainer, and what I believe is a BMP-style fuzz.
Ok, thanks Chris!
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