BLACK FOREST High Gain Preamp - Based on the Bogner Uberschall

[J0K3RX]

hi jim:

funny i have that schemo on my desktop...

i'll try that then before anything else creeps onto my breadboard ...cheers man.

so j201/2n7000x3/ 2n5458x2



oh bollox, i haven't any 2n5458's....guess i'll have to sub em..

KP303A - 2SK30A-R, J201, 2N5457, 2SK30A-Y
KP303E - 2N5457, 2N5458, 2N5459, 2SK30A-Y

J201's work for both but not sure if they are the best choice?  I tried J201's, 2N5457's,2N5458's and 2SK30A-Y's in the end stages with very little difference... BIG differences in the first stage!

J201's, 2N5457's and 2SK30A-Y are my choice for the first stage and 2N5457's, 2N5458's and 2SK30A-Y for the last 2 amplifier/buffer stages.

People are using 2SK117's and reporting that they work well... I don't have any so I have no comment on them.

2N7000's and BS170's work about the same but the BS170's sound a little darker and have a little warmer sound...  same amount of gain.

I know there are a few other subs for J201 and 2N545X but I have not tried them / MPF102, NTE458 etc..

[deadastronaut]

cheers for that jim,  i have it breadboard up to the 5th fet so far( no stack) ...and gain isn't that high really...

i'll check it over again...

[J0K3RX]

cheers for that jim,  i have it breadboard up to the 5th fet so far( no stack) ...and gain isn't that high really...

i'll check it over again...

Are you using trimmers on the 2N7000's by any chance? The source and drain are pretty well dialed in on the schematic @ 43k source and 56k drain... Also R6, R13, R18 and gain pot critical to be attached to +4.5v comming from C18, R23 and R24 junction... without that no gain

[Cap]

@Cap Is your layout verified Riccardo?

+1

Looks like he built it but never heard anything after that??

Maybe I will etch it and try it... Somebody has to, might as well be me, right?

yes It works; I had some issues biasing, but than i realized that I have toasted a couple of fets when desoldering the first layout attempt
The last time I played it, strange things happened: the first 5 minutes pure evil , then volume losses and eq problems..maybe other components are damaged..my bad

However the layout is correct, I'm pretty sure

[miftah]

thanks JOK3RX, i have j201 7pcs and i'll try it

[J0K3RX]

thanks JOK3RX, i have j201 7pcs and i'll try it

I looked at your web page and went to your youtube link... nice stuff! How do you like the Infinity universal guitar preamp by chaosStrings?? I have the schematic and layout for that and I was going to build it. Your youtube vid sounds pretty good!!! Now I am really wanting to build... Do you like it?

[miftah]

I looked at your web page and went to your youtube link... nice stuff! How do you like the Infinity universal guitar preamp by chaosStrings?? I have the schematic and layout for that and I was going to build it. Your youtube vid sounds pretty good!!! Now I am really wanting to build... Do you like it?
[/quote]

I like the infinity guitar preamp, but I do not like
because it uses duble voltage, and I had to buy
another transformer for it.

[J0K3RX]

I looked at your web page and went to your youtube link... nice stuff! How do you like the Infinity universal guitar preamp by chaosStrings?? I have the schematic and layout for that and I was going to build it. Your youtube vid sounds pretty good!!! Now I am really wanting to build... Do you like it?

I like the infinity guitar preamp, but I do not like
because it uses duble voltage, and I had to buy
another transformer for it.

[/quote]

I see the +/-9V bipolar power supply in the schematic..could probably be redesigned to run on 9v or 18v? Haven't ever really looked at the schematic until now. Kinda surprised to see that it's just a BSIAB II with a lot of pre/post eq and filters... I wouldn't have guessed it was a BSIAB, doesn't really sound like one at all..?

[beedoola]

J0K3RK - thanks for doing all the work with this!!

Is the parts list the same for the most recent version as for the first version on page 1 of this thread? I ask because the image/parts list on the 1st pages is easy to read for me than reading the component values on the layout picture.

[hangingmonkey]

Ive got myself a pcb for the blacker forest, will that be ok with the updated no return layout?  Looks similar to me but with the 2 parallel 22k resistors changed to 11k and extra pads for d4.
Which layout should i use?
Any further amendments since?
Thanks

[Bliss]

Well I'm planning to build this effect, great job!
But 43 pages of comments.. Could someone summarize what the changes to the original layout are? Or is there a final layout/scheme?

Thanks!

[pakrat]

I put together a BOM for the Black Forest No Return. I have checked it but another set of eyes would be nice...

Resistors 1/4W 1% Metal Film:

(1) 1M
(3) 68k
(3) 10K
(1) 5K
(1) 1.8K
(1) 100K
(1) 2.4K
(3) 470K
(2) 330K
(2) 1.5K
(1) 1K
(1) 820R
(1) 11K
(1) 220K
(1) 470R
(1) 100R
(1) 100K

Film Caps 35V-50V

(2) 1NF
(1) 100PF
(4) 2.2NF
(1) 470PF
(1) 22PF
(6) 22NF
(2) 470NF
(1) 270PF
(1) 220PF
(1) 1UF
(1) 100NF

Electrolytic caps 35V-50V

(3) 100UF
(1) 4.7UF
(1) 2.2UF

Trimmers:

(4) 50K Linear

Transistors:

(6) J201

Diodes:

(4) BAT85

Potentiometers PCB Mount:

(1) A100K
(1) B500K
(1) A20K
(1) B100K
(1) B50k-B100K
(1) A1M
(1) B1M (Optional Presence pot)

Switches:

(1) DPDT Toggle (Optional Wide Switch)
(1) DPDT Latching Footswitch (Optional Boost Switch)

Variac Board (Still under development and may have changed)

Resistors 1/4W 1% Metal Film

(1) 1M
(2) 10K
(1) 470R
(1) 33R
(1) 100K

Film Caps 35V-50V:

(1) 16NF
(2) 470NF

Electrolytic Caps 35V-50V:

(2) 100UF

Transistors:

(3) J201

Potentiometers:

(1) B250K

[pakrat]

@Bliss I think the layout on page 41 is the most current version, and there are a few builds reported working off of that. Cap's version is smaller but I'm not sure it's 100% verified.

[Bliss]

@Bliss I think the layout on page 41 is the most current version, and there are a few builds reported working off of that. Cap's version is smaller but I'm not sure it's 100% verified.

Thank you pakrat!

[pakrat]

 

[Bliss]

How close does the sound of this project get to the original Uberschall?
Is it a big difference?
Maybe someone who has a video or soundclip ?

[pakrat]

There are a few soundclips littered through the thread. I have built this preamp twice.... the first one was the noisy 5 gain stage version and aside from the noise, it sounded great. It definitely has the flavor of the Uberschall, but was too noisy. Then I built the 4 stage version and have not gotten it to work properly yet, but there are successful builds of that version so I'm still debugging 

[J0K3RX]

I just moved... still unpacking so, should be back in business soon, sorry... 

[hari]

still waiting for another build report . . . 

i have my Blacker Forest PCB waiting for J201s, still confuse with the wiring, can I use only 1 3pdt switch, and ignore another swithces?


also waiting Jok3rx back to business 

[Bliss]

Is it possible to exchange the BAT85 diode for something else?
Since I'm ordering at one shop, does any of these compare?
    1N5817    
      1N5822    
      BAT41     
      BAT42     
      BAT46     
      SB360     
      SB560

Thanks,!