BLACK FOREST High Gain Preamp - Based on the Bogner Uberschall

[deadastronaut]

@stormbringer:   \m/     \m/  ....sounds great man. excellent.

[J0K3RX]

@stormbringer:   \m/    \m/  ....sounds great man. excellent.

c'mon Rob, you know you wanna make one of these and join the "NO HUM CLUB" formerly the "MO HUM CLUB"

Also would be nice to have somebody with your knowledge messing with it first hand!!

[J0K3RX]

after the SMD thread, I'm thinking I may have to get brave (and a new Rx for glasses) and try it super-tiny.

Do it... I ain't afraid of no SMD! Actually I prefer surface mount over through hole, just been lazy and already have a crap ton of through hole parts... I am quite comfortable with SMT since I did work as a SMT rework tech for years and probably have done well over tens of thousands of boards in production... Really small fine pitch stuff too and BGA's etc... The fear factor of soldering SMD has no hold on me what so ever!

[stormbringer79]

Alright. Built the ENGL, Can't bias properly at the moment though, due to a faulty trim pot.
Need to order a couple of new ones. Will check back in a couple of days when i get them delivered and get it all working.

[J0K3RX]

Alright. Built the ENGL, Can't bias properly at the moment though, due to a faulty trim pot.
Need to order a couple of new ones. Will check back in a couple of days when i get them delivered and get it all working.

Damn! So close, yet so far away...

[stormbringer79]

Alright, managed to find a 100k Trimpot, so got it up and running with that. Just gonna fine tune it now and replace with a resistor, and also see how it sounds with a 808 in front. i like it so far. Good work! Although i prefer the sound i get from black forest for chugging parts, the lead sound with this is superior. Gonna have some fun with this after dinner.

[stormbringer79]

Quick and dirty recording with the ENGL, as usual i improvised and didnt learn the stuff i recorded properly before playing ^^ sloppy again. Not really the punch my last recording had due to no bass or drums. but anyway. here's a short audio clip.

https://soundcloud.com/stormbringer79/engltest

[J0K3RX]

Alright, managed to find a 100k Trimpot, so got it up and running with that. Just gonna fine tune it now and replace with a resistor, and also see how it sounds with a 808 in front. i like it so far. Good work! Although i prefer the sound i get from black forest for chugging parts, the lead sound with this is superior. Gonna have some fun with this after dinner.

Ok, your clip sounds great, again!! I agree about the fat low end of the Black Forest as compared to the Engl. I thought the same thing also the BF has a very wide low end and you can get some real good harmonics, squeal notes etc... The Engl has a great lead tone and is really easy to do fast smooth runs with, maybe not as stiff feeling as the BF and a lot of mid range, does really well with the neck pickup as well! I think some tweaking with the tone stack would give a broader wider sound like the BF... Both have a very tight low end attack but I think the Engl is a little tighter, if that's even possible! Great for 7 and 8 string!!

So I gotta ask, how is the noise/hum factor??? The noise/hum is the only thing holding me back on both the BF and the Engl... Do you get a surge of noise when you roll the vol pot back on your guitar etc.. What did you do, not do etc...

Edit: I thought I was fast at throwin things together but I think you got me beat!

~ Jim

[stormbringer79]

Yeah, i agree. I could probably get a little heavier tone from it aswell when i get to experiment more and get more familiar with the tonestack.

I actually decided to build it Stock first to help finding where the hum comes from (although gain pot wires, input and output are shielded), i do get some hum, lower after i replaced the trim pot with a resistor though. but it's still present with my homebuilt OD808. I will check your solutions out one at a time and see where it stops.

I do build quite fast when theres a pcb layout to work with (although i use the perfboard and bending legs from components to match pcb pattern approach), but i've had this project in mind for a while, so i had already bought the parts needed.

edit: oh, right. i forgot. Rollback volume works well, although. at lowest gain pot-setting i get oscillation. only at the lowest 1-2 % though. High pitch sqeal, but might be my home-made traces being to wide and close to eachother somewhere.

edit 2: (getting late, sorry). The black forest i built was with the noise gate addon. it's absolutely silent using my 7-string with volume down, had a small amount of hum with my passive mic 6-string. but i can barely hear a difference when i switch the pedal on with strings muted while running it quite loud through my randall RH100 when rehearsing with my band.

[fretzburner]

What you guys mean with volume down? Not same as volume off?

[J0K3RX]

What you guys mean with volume down? Not same as volume off?

Volume on the guitar... When I turn my volume down on my guitar the noise increases until all the way down and you can still hear the hum... Slowly getting rid of the hum. I thought I had gotten rid of it yesterday with the simple things I explained some posts back but, then I plugged in today and I hear the F@$#king hum again.. not too bad at all but WTF!!! I want it GONE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  

I am getting tired of this sh!t, been chasing this humming ghost for months now!!!! First the Black F&*King Forest and now the ENGL!!! WTFF? Can you tell I AM PISSED OFF?  

And I am not gonna settle for this is "TOO MUCH GAIN" cause that's Bull ShiZZy!!! This has a lot of gain but c'mon, really? It doesn't have too much gain cause when I hook up my TS pedal it has even more gain and the noise goes away? It's the front end of this thing... It's hummin like a F$&kin geiger counter sittin on top of a box of spent reactor rods!!! Bull Sh!t!!!!

[J0K3RX]

Bout ready to issue a ***REWARD*** to anybody who can get me out of this HUMMMMMMMING HELL that I am living in!!!! Find a "LEGIT FIX" for this problem and I will send you a damn near brand new AMT P1 pedal in the box, no scratches and never had a foot touch it, and it DOESN'T HUM...! Who's up for it? The fix has to be a legit fix! Can't effect the tone or the gain and has to retain the "bad@assness" of the pedal minus the HUM! This is not a contest, it's a gift!

If you live in some far off land like Zimbabwe, outer Mongolia or Timbuktu then forget it!

[stormbringer79]

I'm far off (sweden), but i wanna change the reward to atleast 30 more pages of this thread if i find the problem.

Going away for a couple of days right now though, but will start experimenting when i get home again.

[deadastronaut]

CALM DOWN JIM!!!!!!!!...... deep breaths, ..........deep..................deep.................................breathe slowly......in................................out............................in.........................in.................in..................in.................BANG!!!!!...

I understand the frustration of  getting 'nearly there' with home grown stuff!...been there, and will be again no doubt.

I'm pretty sure if you started a thread with that  offer ( with full schemo  and ask that answers be directed/ linked to this thread of course (put a link to here ).

that some of the more knowledgable EE guys would jump on it ....everyone loves a freebie right!......plus everyone gets a fully working schemo....WIN WIN...

btw i live in the congo 

[jymaze]

Probably a good answer would be to use double side PCB with a ground plane, neat ribbon connectors that prevent random cross-talk, and perfect grounding of the enclosure. I am pretty sure it is one of the factors explaining why the AMT pedals do not hum...

It is just harder for a DIYer to get to that level of engineering.

Maybe I am just asking again and again, but how would you describe your hum? Is it like 60-120Hz hum? Is it more like white noise? Is it high pitched? I think I remember you also saying it hums with no input chord plugged in, but I am not sure. We just have to knock down every possible source of noise one by one. Do you still have your 18k grounding resistor at the input?

[defaced]

Bout ready to issue a ***REWARD*** to anybody who can get me out of this HUMMMMMMMING HELL that I am living in!!!! Find a "LEGIT FIX" for this problem and I will send you a damn near brand new AMT P1 pedal in the box, no scratches and never had a foot touch it, and it DOESN'T HUM...! Who's up for it? The fix has to be a legit fix! Can't effect the tone or the gain and has to retain the "bad@assness" of the pedal minus the HUM! This is not a contest, it's a gift!

If you live in some far off land like Zimbabwe, outer Mongolia or Timbuktu then forget it!

If you etch a board, I'll buy it from you and build it.  High gain tube amps are my thing.

[caspercody]

I am not sure what you are using for a power supply, but if you are using a wall wart power supply do you have any filters? I think it was on the "Tube boost + overdrive running off a 9 volt battery" that they were talking about adding some caps, and a voltage regulator to a wall wart to get rid of noise. Scroll down to page 8 on this:

http://www.aronnelson.com/DIYFiles/up/12AU7-6111_Valve_Caster_Summary_Rev002.pdf

Hope some of this helps.

Rob

[caspercody]

Forgot one more thing,,, I read somewhere to put a 100 ohm resistor in after the + voltage connection and before the circuit. Also to put a large cap (470uf) from + to ground, and also a 100nf cap. I think you might have tried this already...

[jymaze]

I think Jok3rx reported noise under 9v battery operation, must not be a dirty power supply then...

[J0K3RX]

Tried it with a new 9v battery and still get the noise... I have a 1Spot power adapter and it must be regulated because it reads a solid steady 9.5v all the time load or no load. I power my other pedals with it (Dr.Boogie, AMT, AMT clones etc) and have no problems, at all. And no, I do not run them all daisy chained... just maybe a TS808 into the preamp pedal straight into whatever, amp, recording interface etc.. I do not run any other pedals nor do I like any other pedals before my preamp, no delays, no chorus, reverb etc... I prefer to add these either after the preamp or not at all and just add them to the recording using VST pluggins... But for the most part I do not like any pedals before or after the preamp with the exception of a tube screamer before the preamp and sometimes I don't even use that depending on what volume I am running at or whether or not the preamp needs a little kick in the ass...

The hum or buzz is a low level, low pitch noise, not high pitched and not what I would call white noise or hiss. You can get an idea of what it sounds like simply by taking your guitar cord coming from your amp out of the jack on the guitar and just put your thumb on the tip of the cord and leave it there. This noise is always present in the background and doesn't seem to be effected by the actual guitar signal nor does it really interfere with the actual guitar signal, just kind of rides along side it or behind it. It seems to almost disappear with the volume all the way up on the guitar but if you turn the volume knob on the guitar back to say around 75% it intensifies and continues to intensify the lower you turn the volume knob to the point where the noise becomes just as loud as the guitar signal and this happens at around 50% volume. If you mute the strings with the guitar on full volume you can hear it but it's not nearly as bad and almost doesn't even exist at that point, but I can hear it, still! Just mainly when you turn the vol pot on the guitar back it surges or builds to a very loud level to where it finally overtakes the guitar signal and from there the lower you go the louder it gets until you have the volume all the way off and then there is no sound except you can still kinda hear the faint hum in your speakers.  

The other day it appeared that I had fixed it and it seemed to be working perfectly!! Then, I unplugged it and put it in the cabinet, came back the next day, plugged it all back in and...... HUMMMMMMMMM  

I removed the 18k resistor from input to ground. It cures the hum 100% but it also cuts/dampens the signal to a certain degree and there is some gain loss. The noise gate gets rid of 85% of the hum but still some bleeds through, I like it better since you can adjust it with a 1k pot and it is actually I nice feature hum or no hum.. If you are running at very high volumes you are gonna get all kinds of rogue noise and feedback so the gate is a cool feature in my opinion.