BLACK FOREST High Gain Preamp - Based on the Bogner Uberschall

[J0K3RX]

I thought I would give this a try and I am damn glad I did! I used the original Uberschall tube amp schematics that I found by accident while looking for something else... This thing is a beast, butt loads of high gain!! 

I made a few changes here and there but for the most part it's true to the schematic. I removed a resistor (470k) going to the volume pot because the volume was a little too low. I added a gain/saturation boost switch and of course the diodes between source and gate on Q2, Q3 and Q4 and that's about it. You may want to experiment with different value pots in the tone stack.. I went so far as to use the same values used on the Dr. Boogie and I may leave it like that, still trying to get it just right...  When converting these high gain preamps over to JFET it seems like the tone stack does not make the transition as well as it should. Probably because of the lower voltages? Anyway, the Dr. Boogie values or close variants seem to work pretty well.

It should be biased between 4.5V and 5v to your liking...

And no, I did not create a schematic... If you want the actual amp schematic PM me and I will send it to you.



http://dl.dropbox.com/u/11178619/Black%20Forest%20Rev1.png   <--Larger image, easier to read.

Board transfer
http://dl.dropbox.com/u/11178619/Black%20Forest%20Rev1.pdf

[pakrat]

Thanks for posting this, it looks very interesting! How does it sound compared to the Dr boogie?

[J0K3RX]

Thanks for posting this, it looks very interesting! How does it sound compared to the Dr boogie?

Well, this is a component for component scaled down copy of the Uberschall Twin Jet super high gain lead channel where as the Dr. Boogie is a component for component copy of the Mesa dual rectifier lead/Red channel... This seems to have more gain, more mids and a lot of clarity on the bottom end, not muddy at all! Great for 7 and 8 stringers, lots of low end punch and explosive chords! Great for 6 string also, just an amazing amount of usable gain...

It doesn't sound at all like the Dr Boogie.. This is a different beast! Same as both amps are different.

If you like the Seventheaven Bogner Ecstacy copy by GoosoniqueWorx this thing spanks it and sends it to bed without dinner

I will try to post some sound clips and maybe some pics of the guts...

Next on my list is the Soldano Avenger

[John Lyons]

Nice...if you post some clips I'd like to have a listen. Thanks 

[pakrat]

Nice...if you post some clips I'd like to have a listen. Thanks 

+1

[tyzjames]

Very interesting, thanks for posting! Would love to build it and compare it with the Seventheaven!

[J0K3RX]

Sorry, still working on getting some time to myself (without everybody up my ass) to make some sound clips!


If anybody has any ideas for different tone stack feel free to share! I would prefer less knobs also... I added the presence knob, that could easily go away! Less may be more in this case... more control over the tone??

[meffcio]

Sorry, still working on getting some time to myself (without everybody up my ass) to make some sound clips!


If anybody has any ideas for different tone stack feel free to share! I would prefer less knobs also... I added the presence knob, that could easily go away! Less may be more in this case... more control over the tone??

As I said to you in a PM, I'm gonna experiment a bit when I finish my exams. I think of shrinking the eq to like 2 knobs and a switch, or something. The casual bass and treble control + presence boost, or maybe a tone stack similar to the Proco Solo. Need time, breadboard, and we'll see what happens then.

[pakrat]

I'm not qualified to make any changes to your layout, but I am definitely a stickler when it comes to heavy gain. I also have a friend with the "real" Uberschall, so I should be able to get a good side by side comparison. In reference to what you said earlier... it sounds great as is, so I'll build it from your beta layout and give you an honest opinion based on my ears. Thanks again for your work on this, I'm psyched to try it!

[J0K3RX]

I'm not qualified to make any changes to your layout, but I am definitely a stickler when it comes to heavy gain. I also have a friend with the "real" Uberschall, so I should be able to get a good side by side comparison. In reference to what you said earlier... it sounds great as is, so I'll build it from your beta layout and give you an honest opinion based on my ears. Thanks again for your work on this, I'm psyched to try it!

I am gonna work on the tone stack tonight... needs some work! Whatever I come up with I will update here... That would be cool to do a comparison to a real Uber! Maybe your friend would let you plug it into the effects return of his real Uberschall, that would bypass the amps actual preamp and the pedal would become the preamp. That would really be a side by side comparison!

[pakrat]

That's a great idea! And in the process, I can watch him get super pissed at me if it sounds just like it. I'll wait for you to post a layout you're happy with.

[J0K3RX]

Ok, this is what (mensur) another forum member sent me in a PM.

"Change source resistor on the buffer with 33K-47K-56K and see what will happen, the buffer cannot track cut-offed signal well and so tone stack becomes buggy."

So, I tried it and it made a BIG difference! Instead of the values he mentioned I tried 10k (Like the Dr.Boogie) and I am fairly happy with it... I may need to try his suggested values as well just to get it dialed in or maybe I will stick a 100k trim pot on there and adjust until I get just the right value  

In short: What I did was I changed R16 from 100k to 10k... All the pots are stock value from my diagram.

I don't think I will be changing the layout since it's a direct copy of the amp.. however, I believe that I will be changing component values here and there to get it dialed in better. Especially if others start to build it and find improvements etc... I mean, that's what this forum is for right!?  

[pakrat]

Mensur made the Randall RG emu right? I was just reading a few posts regarding that layout because it was next on my build list. I think a trimmer could be a good idea so you can mess with it to find the "perfect" value. Either way, I can build this as is and experiment with different values for R16. Looks like I'm placing another parts order this week........

[J0K3RX]

Ok, here's an idea I use a TS808 in front of everything, preamps, amps etc.. Just gives it that extra "kunk" sound and feel for lack of a better word. It also drives the notes when doing leads etc.. I know many players that use them like this. Even though the preamp has plenty of gain this just seems to add the cherry on top of the sunday! I mainly use it as a clean boost where the level is almost all the way up and the drive is all the way down. So, what I was thinking is maybe add a Mosfet/Jfet boost circuit foot switchable in front of this preamp like on the Wampler Triple Wreck, not many parts involved and I could get rid of the Presence knob and put a switchable low pass or no switch to accommodate the additional boost knob/pot Thoughts?

[pakrat]

Sounds good to me since I use the tubescreamer the same way.

[J0K3RX]

Sounds good to me since I use the tubescreamer the same way.

Ok, next question.. Which boost circuit should I use? I kinda have my ideas but I just want to get some educated opinions first. I want it to be as close to or better than using the tubescreamer with the level cranked and the drive all the way down... Also I don't want to run into any funky squealing noises or pops etc..

[pakrat]

The only one I know of is the AMZ booster:   http://www.muzique.com/schem/mosfet.htm

[meffcio]

You can put any kind of booster there, but the question is will any booster other than the TS maintain the Tubescreamer's abilities in front of the Black Forest. To be honest, I never played any TS, so I don't know the nature of that certain stompbox. I'm not sure if there are sound reasons for many people using it as a booster. Maybe a simplest unclean booster will do the task, or maybe the TS is really the only way to go.
Any experience with that subject, forum people?

Maybe we'll have to analyse what TS actually does in that certain booster setting. How much db of gain, how does it alter the tone, etc. It should be easy to recreate it with a simpler device then, w/o unnecessary controls.

[J0K3RX]

Here's a quick crappy demo, dry as a bone.. too much gain

http://dl.dropbox.com/u/11178619/BlackForest2.mp3

[meffcio]

Here's a quick crappy demo, dry as a bone.. too much gain

http://dl.dropbox.com/u/11178619/BlackForest2.mp3

What was the recording chain? I always make that as simple, as I can - guitar>effect>line input in the PC>some guitar cab impulses on reaper, using LePou LeCab plugin.
When I put your sample through some impulses it sounded better, you know. ;p