BLACK FOREST High Gain Preamp - Based on the Bogner Uberschall

[pakrat]

The squeal goes away when I back off the tone on my guitars.  It may be fixed by reducing the boost resistor? I'll check that and report back, might need an active and passive switch setup here.

[J0K3RX]

New BF.... Layout not verified, yet. This is the normal 4 gain stage version and buffer after tone stack. This should not have a noise problem and still have a very good amount of gain.



Larger Image
http://dl.dropbox.com/u/11178619/New%20Preamps/Blacker%20Forest%20-%20On-board%20Pots%20Large.png

Board Transfer
http://dl.dropbox.com/u/11178619/New%20Preamps/Blacker%20Forest%20-%20On-board%20Pots.pdf

[jymaze]

Thanks Jok3rx. I remember you said it lacked balls without the 5th gain stage, but I am sure it is still very much kicking anyway.

[J0K3RX]

Thanks Jok3rx. I remember you said it lacked balls without the 5th gain stage, but I am sure it is still very much kicking anyway.

It still has balls and I believe I said that before I found the boost resistor...? And, it can be driven with a tube screamer to achieve the same or better... Main thing is no hum! I will make one with the 5th stage also. I was thinking of making one with a couple mosfet stages too (jfet/mosfet/jfet/mosfet/jfet/TS/jfet)

[stormbringer79]

I'll be happy to build and confirm your new stuff mate. Although i got a couple of projects i need to get done first. (Designing a programmable pedalboard 4 momentary buttons, 6 send/returns and controlled by a pic and lcd, in order to make it programmable).

[J0K3RX]

I'll be happy to build and confirm your new stuff mate. Although i got a couple of projects i need to get done first. (Designing a programmable pedalboard 4 momentary buttons, 6 send/returns and controlled by a pic and lcd, in order to make it programmable).

Ah... I still have my PIC programmer from making rapid fire xbox controllers. I used WinPic and 12F683's, I could get them to do quite a few things. I wish I would have kept going with it...

[stormbringer79]

I work as a programmer, so it comes quite natural to work with pics, but if you want an easy way of coding for pics, check out flowcode, does it for you with block diagrams. Its not perfect, but can help you alot.

[J0K3RX]

I work as a programmer, so it comes quite natural to work with pics, but if you want an easy way of coding for pics, check out flowcode, does it for you with block diagrams. Its not perfect, but can help you alot.

I might get back into it if I ever come up with a nice preamp that I am satisfied with... 

I decided to start another thread for the AMT E1 clone but I posted it in "The Lounge" instead of Members Only... Dumb I am!
http://www.diystompboxes.com/smfforum/index.php?topic=102143.0

[pakrat]

Parts ordered, Thanks JOK3RX!

[J0K3RX]

Ok, very good news!!! I am going to bed a happy man! I built this thing with 4 gain stages and it is THE BEST!!! No noise, no hum, no buzz!!! Tons of gain... Tone stack works very well, tone to the bone! Boost switch works very well! Wide switch works very well! Everything kills!!! I am DONE with this and this one is going into a box!! Love it!!! This is better than the ENGL, better than all of my stuff period!!! Details tomorrow, I gotta get some sleep Stay tuned!

[jymaze]

Glad you could get that to work! I am working on one of these right now and it was the same: Too much gain makes it noisy and squealy. It still has 5 stages, I think I'll either dump one or scale down the gain at least on 2 stages. I hate desoldering so it will be scaling down the gain. It is very specialized and its goal is to give you one specific sound: Codename is "Petruccifier"... I hope it will be postable soon, I am sure some people will be interested. Basically it is an attempt at a Mk IIc emulator, with less knobs. I can tell you it is scoopy!

[pakrat]

Ok, very good news!!! I am going to bed a happy man! I built this thing with 4 gain stages and it is THE BEST!!! No noise, no hum, no buzz!!! Tons of gain... Tone stack works very well, tone to the bone! Boost switch works very well! Wide switch works very well! Everything kills!!! I am DONE with this and this one is going into a box!! Love it!!! This is better than the ENGL, better than all of my stuff period!!! Details tomorrow, I gotta get some sleep Stay tuned!

Well it's about friggin' time!! 

[J0K3RX]

This is really puzzling me I can't figure out why this one has so much gain with 4 gain stages? I'm not complaining at all but this just isn't making any sense... It has as much if not more gain than I was getting with 5 gain stages! I don't remember it having anywhere near this much gain when I built the first one with 4 stages!? Weird!? WTF?? Wondering if I got a resistor wrong somewhere but I can't find anything, yet. When I get time I am gonna have to go over this thing thoroughly!

jymaze - Petruccifier? I want one!  

[jymaze]

Maybe you used a combination of fets that yield higher gain just by chance... I did a run of jfet testing last week on 2N5457 and J201. Quite a bit of variation, sometimes wild. I will just use the ones with the lowest Vgs off since they yield higher gain. It is especially crucial for the first stage because more gain equals less noise generated there. I would select low Vgf off for better results (at least I think it would be better).

I am glad all this got finally fixed. I was right somehow... drop a stage. You can keep your AMT pedal though...

[J0K3RX]

Maybe you used a combination of fets that yield higher gain just by chance... I did a run of jfet testing last week on 2N5457 and J201. Quite a bit of variation, sometimes wild. I will just use the ones with the lowest Vgs off since they yield higher gain. It is especially crucial for the first stage because more gain equals less noise generated there. I would select low Vgf off for better results (at least I think it would be better).

I am glad all this got finally fixed. I was right somehow... drop a stage. You can keep your AMT pedal though...

I thought about the jfets but then I remembered they are the same jfets that I had in the first BF which I thought didn't have enough gain using only 4 gain stages, remember? That was the only reason I added the extra stage... So, the jfets I am using now are the same ones that I used before minus one of course. In any case, I even tried others and it still has a ton of gain.. weird? I haven't really had time to go over it again since I built it but I might have a look at it tonight.

Waiting for the Petruccifier!!! 

[J0K3RX]

Ok, totally off topic...   Anybody ever try the EMG active circuit?? Like either of the two on this link?
http://revolutiondeux.blogspot.com/2012/06/active-pickups-how-do-emg-do-it.html

I want to mod my el cheapo' 7 string stock pickups but wondering if it's a waste of time?

[pakrat]

Wow, that's very interesting, I have a bunch of el crapo pickups to try this on.

[J0K3RX]

Ok, back to the BF... I don't even have shielded wires on this one and it has very little noise (but I HIGHLY RECOMMEND using shielded wires!)

I think I know where all the gain is coming from! The boost resistor! Instead of trying a bunch of resistors I just stuck a 100k trim pot on there and dialed in what I thought was the right amount of high gain vs. noise ratio and that is plenty!! Not sure of the value as I have not measured it yet since I have been playing non stop since I built it!   Which is nice for a change!!! I think this thing sounds better than ever!! I am also using the Hotline cab simulator and I am loving it!!! Very Happy I am!!

Edit: Oh and by the way, if you put the 4.7uF electrolytic on the first stage on a switch between 1uF and 4.7uF it's like a "tight" switch! Tightens up the bottom end! Or you can put them both on a pot and have a fake variable cap and dial in the tightness!

jymaze - Still waiting for the Petruccifier!!! See, you shouldn't have said anything...

[pakrat]

A "tightness" pot sounds great, and no gate on this one?

[J0K3RX]

A "tightness" pot sounds great, and no gate on this one?

No gate, but you can add it in if you want...I would be inclined to put it in if it were foot switchable but I really don't want another footswitch... Unless I build it into a 1590DD? But, I really want to add a clean channel! That's one thing a lot of these preamps lack is a clean channel and they just have true bypass. I don't really like that... It's good for home/studio/recording applications but not so good for live..