Dr. Boogey finished...but i have some questions about gain and mid pot and...

[gigimarga]

hello,

i just finished dr. boogey from gaussmarkov's site (thx a lot to you and to all that worked on it ) and it sounds fantastic...an old blues/hard rock/early metal sound...no hiss...very good definition on chords...fabulous...for sure this is my favourite distortion box...

but when i had read about it (and heard) i hoped that it will sound very aggressive...something like digitech death metal...i used for all the trannies only new j201...can i modify it to sound more aggressive (without a booster...i can put a mosfet booster in front of it but i don't want to do this)...ideally a switch between these two settings...i have biased all the trannies with the trimpots maximized (or minimized...at the end or the begin...the voltage is something like 7.5-8.5 V on all trannies)?

second question...it is possible to modify the mid pot to act like the rocktron's rampage mid pot...very scooped sound...i played it sometime ago and i was very impressed about it...they claims that it has -30db...

best regards and thx!

[Auke Haarsma]

What is your supply voltage? If it's 9V I'd bias the j201 more around 4.5V.

With how it is currently biased you'll have something like this:

Asymmetrical clipping. Very fast clipping on the upperside, no clipping on the lower side.

If you bias it more towards 4.5V (1/2Vcc) then you get a more evenly clipped image:

both pics are scope readings from my Dr Boogey

Ofcourse, you can bias by ear. But to my ears a bias around 4.5V sounds smoother and deeper than a bias around 8V.

To increase/alter the gain, play around with different values for C1. Putting a big cap in there will get more gain from Q1.

[dschwartz]

auke..thos pics are amazing!!

gigi...as auke said, you have to tweak the trimpots..i like doing that by ear,,start tweaking from the output trimpot to the first one, maximizing the level of hiss & noise (that indicates that you are achieving max gain)..then..tweak some more to adjust it at taste...be careful though, the sweetspots are hardly an 1/8 of turn of the trimpots...

in order to get a more scooped sound.. lower the 6.8nF cap at the tonestack to 3.3nF or even down to 1nF..the lower.. the scooper...
good luck!!!

[Hanglow]

I biased mine at around 5v, sounded a wee bit better I think

those are cool pics

[gigimarga]

thx a lot man...very nice pics!

my supply voltage is 9.22V...i biased it by ear like dschwartz said...i need to maximize (or minimize all the trimpots) to get a hard distorsed sound...i didn't try to see it on oscilloscope until now, but i will do...the only problem is that i don't find a free oscilloscope program

[gigimarga]

thx for your advices...i will try as soon as possible to decrease the cap...i like very much the hard scooped mids

[dschwartz]

if you have to turn the trimpots full (or min) there´s something wrong with your build....ussually the sweetspot is around 12-20k Ohms from the trimpots..have you checked the orientation of the fets? or try tuning the trims with the voltmeter to get near 4.5v..this thing has a lot of gain..and..check your trimpots.. maybe they are 10k and not 100k so they need to be at full to get near 4.5v

[gigimarga]

i couldn't bias the trannies at 4.5-5V...the trimpots can adjust the voltages between 7.5-9V ...and i don't understand why ...

[gigimarga]

if you have to turn the trimpots full (or min) there´s something wrong with your build....ussually the sweetspot is around 12-20k Ohms from the trimpots..have you checked the orientation of the fets? or try tuning the trims with the voltmeter to get near 4.5v..this thing has a lot of gain..and..check your trimpots.. maybe they are 10k and not 100k so they need to be at full to get near 4.5v

man, you're right...a seller will gonna die ...and me too ...all the trimpots are 10K, not 100k...i was very hurried and i didn't verifiy!!!

[Auke Haarsma]

You could hook up a 'normal' potmeter, bias correctly, measure the pot and put in a fixed resistor of the right value. That's what I did after experimenting with the trimpots. Most where around 30k-40k iirc.

@pic lovers: scope is a really nice tool to visualize sound

[dschwartz]

if you have to turn the trimpots full (or min) there´s something wrong with your build....ussually the sweetspot is around 12-20k Ohms from the trimpots..have you checked the orientation of the fets? or try tuning the trims with the voltmeter to get near 4.5v..this thing has a lot of gain..and..check your trimpots.. maybe they are 10k and not 100k so they need to be at full to get near 4.5v

man, you're right...a seller will gonna die ...and me too ...all the trimpots are 10K, not 100k...i was very hurried and i didn't verifiy!!!

haha.. that was a long shot..but BINGO!!

you can try different resistors replacing the trimpots..when you get 4.5v or so..put those resistors replacing all trims...new jfets have not that huge tolerance now...so, you can give that a shot.. it sould work..although the trimimg tuning for me is the "sound tailoring" fun part of the build...try different fets, too..some clip nicer than others...

[gigimarga]

i replace the pots and it sounds much better...for me it's by far the second best distortion i ever heard...first remains in my soul rocktron rampage...if  "dr. boogey" could have the mid scoop of rampage i will be the most happy man on the world...

by the way...i doubled the cap for the "presence" and sounds better for me...i halfed the "mid" cap but it's far away from rampage...i will try using a 1nF cap tonight...

best regards and thx a lot all!

[gigimarga]

i biased all the trannies at 4.5-5V and it sounds much better...but also i discovered his "nice and strong" hiss...i hope when i will put in a box, using shielded wires, to be ok...

[WLTerry]

Just play with the tonestack using the ToneStack Calculator software from here: http://www.duncanamps.com/tsc/

Play with the pots, caps resistor and find your mid scoop you're looking for.

[gigimarga]

thx a lot...i use the "duncan tone stack" from a long time ago...but in this case i think that it's more complicated...i put the mid cap at 1nF and it sounds more like i want...