demeter fat control pcb?

[B_of_H]

Man, I've been loving this circuit!

it really makes the ego driver rawk!  (best placed after the ego circuit)

There are so many applications for this thing IMO and perfboarding it isn't something I want to do again. 

http://freestompboxes.org/viewtopic.php?f=7&t=10435

[maysink]

+1

Looks interesting...

[B_of_H]

+1

Looks interesting...

the idea of being able to put a boost later in the chain really adds a lot of options.  For instance you can put a strat through a wah then add mid's like a humbucker after the wah which is a cleaner, less honkey sound but with the girth of a humbucker etc...  If you put the hotter signal into the wah it really changes the sound of the wah. 

[Myramyd]

I am surprised there aren't more projects like this one.

Mids can be tricky, for so many reasons. This would be a useful board for quite a few applications. Also great just for utility--sticking it in different spots in the pedal chain to see where it makes a difference and how it reacts both pre- and post- certain pedals.

J

[gtg975n]

+1.  Would love to try adding this to a transparent overdrive for an added "presence" control.

[madbean]

I'll make this one happen. It does look promising.

[maysink]

Good news, everyone!

[B_of_H]

i'm playing around with this circuit a little and i'll post something with my thoughts kinda summed up eventually.  So far:

- There is a slight boost when engaged no matter where the fat/flat knob is set, perhaps this could be changed to a trim OR even a knob on the outside (boost + mids) OR it could also be a 'mid-boost and buffer' unit with only a few small mods.  I was thinking about a simple output volume pot (prior to the 220k to GND?) with the signal coming in lug 3 and out lug 2 with lug 1 to GND but I'm guessing that might be overkill as it doesn't have all that much boost to begin with.  perhaps a 5k pot or 2k?

- per FSB: it boosts 200hz to 1khz (up to 14db), I think this is about perfect although some may want to know how to adjust this slightly although I feel like it's pretty much perfect where it is.  (i'm loving on this circuit right now, subject to change )

- I've tried about 10 opamps so far.  I don't have the 442CN but i've tried the following: LM1458, tlo82, opa2134, tl072, 4558, lf353n, jrc4580d and a few others.  So far i've liked the opa2134 in there the best as it is a little more articulate and open sounding with slightly less output than most of the others.  I just found a few others and IIRC the opa2604 has a little less output than the opa

- I built this exactly to spec I believe including 22p silver mica caps

[madbean]

The best way to control the gain would probably at the first stage. A variable resistor could replace the 100k resistor in the feedback loop of the first amp. I'll see about incorporating this into the layout. Actually, I already finished the layout!

Although the frequency response could be altered I don't know the use of that yet. 200 - 1kHz is pretty broad. You could push it up into the 2-3k range to be more of a presence control rather than mid-range.

Another alternative to the LF442 is the TL062, which also has low power consumption. That's probably what I will try first, since I don't have the 442 either.

[B_of_H]

The best way to control the gain would probably at the first stage. A variable resistor could replace the 100k resistor in the feedback loop of the first amp. I'll see about incorporating this into the layout. Actually, I already finished the layout!

Although the frequency response could be altered I don't know the use of that yet. 200 - 1kHz is pretty broad. You could push it up into the 2-3k range to be more of a presence control rather than mid-range.

Another alternative to the LF442 is the TL062, which also has low power consumption. That's probably what I will try first, since I don't have the 442 either.

sweet. 

[madbean]

Currently, the layout is very similar to the Thunderpuss: narrow, with angled ends and space for a PCB mounted pot. How does everyone feel about this? My thoughts were to try to get it in a 1590A, but I don't know how easy this would be to do. Should I make it larger and just assume everyone is okay with it going in a 1590B?

There is another size that the current layout could go in. It's the 1550Q / 1550P
http://www.mouser.com/Search/Refine.aspx?Keyword=546-1550Q
http://www.mouser.com/Search/Refine.aspx?Keyword=546-1550P

The Q is 2.36 x 2.17 x 1.06 and the P is 3.15 x2.17 x 0.83. The P might not be tall enough...I'll have to measure a 3PDT!

[B_of_H]

the smaller the better IMO. 

[madbean]

This one is in the bag. Sounds good! The gain control worked out well....it adds enough versatility between unity and boost to warrant its inclusion.

The current board is a little too big for a 1590A, though. Since I only plan to offer one version, what's good for everyone? One knob or two?

Also, I think this one is probably best as true bypass. Does anyone care about being able to use it as buffered bypass?

[B_of_H]

The gain control is an awesome idea! 

Tb for me as well.

[Myramyd]

I like the idea of the second knob there so you can change it on the fly for different amp setups.

J