Build Report: Dr. Boogey

[gaussmarkov]

i updated my layout of dr. boogey to include 220pF caps on Q1, Q2, and Q4 from drain to source.  i think i got it right, but it is late. 

see http://gaussmarkov.net/index.php?page=layouts#drboo

[John Lyons]

The layout looks good. I like when all the off board connections can be brought to the boards edge.
I emailed marty and he liked the Tone stack less version a lot. Although he did use an EQ pedal after it...
Thanks gaussmarkov!

[gaussmarkov]

john,

re the layout:  super.  i just updated the tonestackless version to have the "miller caps" as well: http://gaussmarkov.net/index.php?page=layouts#drboons

re marty:  i saw once that Marty said that he had added a BMP stack to a later dr. boogey build and that he liked that a lot too.

buck,

i hope the studying has gone well! 

all the best, gm

[John Lyons]

Well...since we have hijacked this thread and it seems to by you and me Gaussmarkov...

I was playing around with the DB today after I was tweaking a DOD analog delay I noticed a pretty drastic thing.
When I played straight into the DB the tone was...well.."normal"... Then I plugged in the delay after the DB and the tone got very muted, basically a big loss of high end. Bypassing the Delay made no difference. I though it was just a fault of the delay but I tried it with another distortion and the tone remained the same (sounded the same with or without the delay in line).

The DB has a 1M output volume control. The Alternate distortion I used has a 10K volume pot. Big difference!
The 1M is pretty high impedance and the 10K is much lower.
In the amp version the preamp is fed to the phase inverter and to the power tubes so the high inpedance is needed. In the pedal version a low impedance output is better as pedals coming after want to see a low impedance at the input (and use a high impedance input).
The output is loading down the input of pedals next in line. As far I as know this is the case. The fuzz face is generally a 500K output volume pot and this has a good amount to do with getting the brightness out of one. With a lower value pot they get pretty dark and of muddy.
At one point a while back I had a 250K voume pot installed but I didn't take note of the issue here.
Food for thought and something more to remedy! I just hope that something like 100K will keep the volume level.

Cool that you added the miller caps to the tone stack less version too!


John

[John Lyons]

Master Volume pot test.

10K= to little volume and it made the treble control shift frequencies in an odd way
50K= didn't have a 50Klog  to try...
100k= good amount of volume and treble acts normanl again. Used with said delay after was still a little dulled but better than 1M for sure.
1M= sounds good but way too high of an impedance for an output control. A bit too trebly possibly. Didn't play well with other pedals that came after it.

Seems like the 100K is the way to go. I was always thinking that 1M was far to high for the output impedance.

John

[gaussmarkov]

hijacked?   how can you call this finding about the output pot hijacking?   this is a thread about building the dr. boogey!

john, this is really good for folks to know.  following marty, i just used a 100K in the first place, which was lucky for me.  but hardly useful to other builders.  the 1M was unusual, but i thought it was connected to the tone stack arrangement with the transistor on the front end.  shows what little i know. 

or knew.  now that you say it, the high impedance of the output is obvious and so are it's potential effects.  a quick skim thru the runoffgroove emu circuits reveals a 100K master volume on every one.

nice work and thanks, gm

[Nashtir]

Hi guys, just finished the scaled down tonestack version, and what to say, WOW!
Absolutely no squeals an no hums without shielded cables! great sound as kown i think better than the previous version, more tube-like!thanks to you all guys!

[Destructos]

Has anybody tried bringing the tone stack portion to the front of the circuit for a pre-distortion tone shaping function instead?
And leave post eq to the amp, a la tonestackless style?

BTW, for 9v usage, I can just leave the trim pots at 100k ohms... right?

[John Lyons]

You will need to adjust the 100k trimmers for 4.5v or so at the drains of the fets. You can get by with 50K trimmersif you use them.

The DB has a lot of tone shaping at each stage already. The tone stack will have much more control where it is at the end of the circuit.
Unless you only use the DB as your only pedal you will not be able to use your amp eq to get the same response from the DB circuit.

John