DR. L3CT3R - Based on Laboga Mr.Hector High Gain Preamp

[J0K3RX]

Ok, I love how these amps sound so I made this jfet/mosfet preamp from the good old Russian schematic... I have not tested it, yet. Pretty sure it will work! Look it over and see if you can find any mistakes?

Here is the real amp demo from Ola
https://www.youtube.com/watch?v=8LH4a6BLrx4

Here is a demo I found of this pedal built from the Russian schematic... Sounds pretty damn good!
https://www.youtube.com/watch?v=__7R3oZPjnM

Say hello to DR. L3CT3R - Named after one of my favorite characters, Dr. Hannibal (The Cannibal) Lecter  



Transfer... if you dare!  
https://dl.dropboxusercontent.com/u/11178619/DR.%20L3CT0R/DL-1.pdf





Large layout image
https://dl.dropboxusercontent.com/u/11178619/DR.%20L3CT0R/DL-1.PNG

A pedal maker once tried to test me. I ate his liver with some fava beans and a nice chianti.  

[J0K3RX]

Ok, as I suspected there were a few minor mistakes on my first layout... I have corrected them and this layout is 100% verified!!! Sound is amazing and no unwanted noise just brutal tone and high gain! The sweep pot lets you dial in a huge variety of tones from heavy scooped mids to tons of mids and everything in between! Love it!! Sound demo soon...

Transfer:
https://dl.dropboxusercontent.com/u/11178619/DR.%20L3CT0R/DR.L3CT3R%20VERIFIED.pdf

[deadastronaut]

cool jim,

look forward to the face eating demo 

[Quackzed]

On the schemo, it looks like a sweep switch and not a pot, i'm guessing youve replaced the 22k/68k and spdt with a 100k pot? you may want to revise the schem to reflect the change to avoid confusion down the road. amp clip sounds brutal! i like your layouts as well, easy to read and nice and neat with the board mounted pots. good stuff!

[J0K3RX]

This pedal is one of the best jfet/mosfet type preamps I have built, ever... and I have built a couple It works perfectly, no hum or noise and the tone stack has a wide range of tones when used with the "sweep" pot! I seem to be able to dial up a Marshall to a ENGL to a Bogner to a??? I sweeps through them all I love it!! I will post some sound clips, soon..

Meanwhile, check this out..
http://www.diystompboxes.com/smfforum/index.php?topic=104608.0

[J0K3RX]

Ok, here is a quick chunk demo just to show the function of the "sweep" pot.. I am playing and turning the sweep pot a little bit as I go. This obviously has no musical value what so ever, just to show what effect the sweep pot has... I am using guitar > pedal > Lart - simple cab sim > into the computer with a tone port GX > into Reaper with a small bit of 275ms delay. No other processing other than the delay

https://dl.dropboxusercontent.com/u/11178619/DR.%20L3CT0R/DRL3CT3R.mp3

I almost forgot to mention... I changed the gain pot to A250K

[JebemMajke]

For a while now I'm considering making an amp with "Krankenstein", "E3", and perhaps this thing as "dirty" preamps and two clean preamps with a rotary switch to choose between them. My question is would it cause a lot of hum because of all high-gain circuits inside?

[fretzburner]

JOK3RX  you made me build again with this demo.I think this one is better than our Engl.

[J0K3RX]

For a while now I'm considering making an amp with "Krankenstein", "E3", and perhaps this thing as "dirty" preamps and two clean preamps with a rotary switch to choose between them. My question is would it cause a lot of hum because of all high-gain circuits inside?

Not sure...? I would think that you could do it, try and see. Maybe when you switch from one preamp to another have it cut the power to all but the one you have selected..

These preamps with mosfets only on stages 2 and 4 sound better and are more stable! There is almost no noise and there is no hum at all... Clean up very good with the volume knob on the guitar etc... Very tube like! I have the VHT done now... will post that later

[JebemMajke]

Well I haven't tried any of these "only 2 mosfets" Russian preamps, but I like both your demo and that youtube link. And I do believe you when you say that these things have less noise than Krankenstein, E3 and others, but i really like Krankenstein .

[J0K3RX]

I just noticed that I have two 470pF caps coming off the gate to ground on the 4th stage... I removed it but didn't really make any noticable difference.

By the way, BS170's can be subbed for the 2N7000's... I have tried them both but I think the 2N7000's have a little bit more edge.. The BS170's sound a little warmer. Both produce about the same amount of gain.

[temol]

necrobump again...

My take on Hector. Sounds ok, but it's missing something.. not sure what.. punch, tightness. I liked it better when it was on a breadboard.




T.

[rankot]

Anyone care to share schematic?

[temol]

Here's the schematic. Replace KP transistors with J201's.

T.

[rankot]

Thanks!

[J0K3RX]

necrobump again...

My take on Hector. Sounds ok, but it's missing something.. not sure what.. punch, tightness. I liked it better when it was on a breadboard.


T.

Looks good man! I dunno, my Hector sounded "pretty good" but, didn't exactly sound like the Laboga amp.. 

You can try this..
https://www.dropbox.com/s/4glrizblqvfg569/Buzzefallx2.jpg?dl=0

[temol]

J0K3RX - thx for the schematic. I'll try it out soon.

T.

[J0K3RX]

J0K3RX - thx for the schematic. I'll try it out soon.

T.

Damn T!!! You came to kick @ss and chew bubble gum.. and you're all out of bubble gum!! I'm gonna call on you when I have a question or need help... You have built just about every damn preamp and you're debugging TrueVal's designs as fast as he comes up with them!  Great work man!! Respect!

~Jim

[rankot]

How to implement Sweep pot (saw it mentioned somewhere)? 

[temol]

Replace tone stack slope resistor with a potentiometer. Here's the example

T.