Build Report: Dr. Boogey

[erick4x4]

Just built a Dr. Boogey, and I am really impressed with it. I knew it would be a great high gain, but it really more versatile than I thought. I can get a mellow distortion or a huge distortion.

Just wanted to say how much I like it.

I changed the gain pot to a 500k to lower gain, and upped the 20pf to 150pf to tame a few highs.

Just wanted to say that I like it a lot.

[Bucksears]

Just out of curiosity:
1) Did you use my layout? I'm wondering if anyone is still using it because I updated it to spread the parts out a little more and include pads for 'Miller caps'.
2) Did you use all J201s?

It's an awesome distortion with a lot of range, if you can tame the noise.

- Buck

[John Lyons]

I had not played through the DB for a while and last night I put one in a box that was sitting out naked for a while.
Man! I really like this circuit. Its so responsive and articulate. I used your layout buck. I have since made a layout of my own that includes the miller caps and more room in between parts. All 201s here...

John

[luap77]

Buck,

Where would I find your updated layout and trace for Dr Boogey?

Thanks.

Paul E

[gaussmarkov]

Just out of curiosity:
1) Did you use my layout? I'm wondering if anyone is still using it because I updated it to spread the parts out a little more and include pads for 'Miller caps'.
2) Did you use all J201s?

It's an awesome distortion with a lot of range, if you can tame the noise.

- Buck

interesting.  i'll have to take a look.    i also recently redid my layout so that i could get the pot connections
all on the one side of the board and in order -- and to make it easy to remove the tone stack if desired.  all of those caps
and resistors are on the same edge of board.  it occurs to me now that i meant to go back and make an alternative pcb
for the tone-stack-less version.

i think your original layout brought a lot of joy to the forum.  i bet the new one will, too.

all the best, gm

[gaussmarkov]

bucksear's layout and pcb are here:  http://www.4thlevelmedia.com/stompboxes.html

nice work! 

[luap77]

Thank you gm.

Could I please confirm a few things:

Is the layout at the link http://www.4thlevelmedia.com/stompboxes.html
actually the new layout with the Miller caps that Buck is referring to?

Is there a schematic available for Dr Boogey with the Miller caps included and labelled? Where might I find this please?

Thanks again.

Paul E

[John Lyons]

The layout above is the same old one.

John

[gaussmarkov]

The layout above is the same old one.

John

sorry.  i assumed that because it was on a page with other layouts, i had found the location of bucksears' treasure chest.

[gaussmarkov]

The layout above is the same old one.

John

sorry.  i assumed that because it was on a page with other layouts, i had found the location of bucksears' treasure chest.

hmm.  i just did another round of searching.  buck said he finished the layout on oct. 23 and all links to his work are the
same as the one that i gave above.  but none to a boogey with miller caps.  at least that i could find. 

buck!  come back! 

[John Lyons]

Gaussmarkov

Although the "tonestackless" version would save a little space and a few dollars I really think it adds a lot of flexibility to the circuit. The bass control seems to live at 80-100% but other than that the mid, treble and presence controls are very interactive and get moved a lot depending on the style/tone your going for. The mid control allows you to get those scooped metal sounds.

I'm not sure Buck has posted his version 2 layout...

John

[gaussmarkov]

Gaussmarkov

Although the "tonestackless" version would save a little space and a few dollars I really think it adds a lot of flexibility to the circuit. The bass control seems to live at 80-100% but other than that the mid, treble and presence controls are very interactive and get moved a lot depending on the style/tone your going for. The mid control allows you to get those scooped metal sounds.

I'm not sure Buck has posted his version 2 layout...

John

hey john,

it's always good to get your input.  i don't want to discourage anyone from building the full monty.    and i already have a complete version.  (well, it doesn't have buck's "miller caps.")

i had two reasons for posting a tonestackless version (which is up now by the way).   first, several folks have asked for a tonestackless version, or something simpler.  not for the sake of cost or space, but because they felt that the 3-knob version really wasn't worth it.  and not necessarily for the dr. boogey specifically, but for such amp emulations generally.  another example is doug's meteor.  my second reason was that leaving off the tonestack shows folks one way to do something else.  some will want to put a single-knob stack in there instead, like the bmp's, and a tonestackless version also shows where to cut and paste. 

so it just seemed helpful to me to offer the second version.  it's also helpful to hear a range of opinions and experiences.  so i'm glad that you chimed in!

from buck's question, i thought it sounded like he had posted it.  but then nobody has shown up with it yet.  so i guess he was saying that if there was interest he would work it up for sharing.

all the best, gm 

[Bucksears]

No, sorry guys, the one that's on my site right now is my old/original DB layout. It's just a matter of exporting as a .bmp or .tif and saving it up there.
I'm working on studying for my MCP exam (MS 70-270) this week, so I've been a little busy. I'll try to post it tonight, if possible.

- Buck

[Victor]

Congrats! It is indeed a nice circuit, I've built mine recently, still working on box and some issues (bad bassy hum through my Laney LC30II, but in my cheapo SS practice amp that does not happen, go figure it out )........ maybe needs a rewiring in pots, it's running on two batteries in series, aprox. 18,5V....... it fits "almost" nicely in a 1590BB.......

[John Lyons]

Gaussmarkov

I agree, it's nice to have options. Making a layout without the tine stack would be a much easier build. Or at least with the BMP tone stack would be interesting, Especially if you use Jack Orman's Body mod in the AMZ Presence control. But then you have tw tone knobs, "fat and skinny" knob and then "Body"

How does your DB sound without the miller caps? All J201s and no squeal?
I must have had a couple screamer FETs in mine because My first build was out of control. But my second build was all 201s with the miller caps and stock on all the other parts and it was well behaved. I use shielded wire from the jacks and switch to the board though...

Thanks for your work on your site. some good stuff there as well as some nice layouts.


John

[gaussmarkov]

hi john,

I agree, it's nice to have options. Making a layout without the tine stack would be a much easier build. Or at least with the BMP tone stack would be interesting, Especially if you use Jack Orman's Body mod in the AMZ Presence control. But then you have tw tone knobs, "fat and skinny" knob and then "Body"

good idea! 

How does your DB sound without the miller caps? All J201s and no squeal?

my build, which was awhile ago (i completely missed the miller cap discussion  ) was all J201s, no tone stack, and shielded leads everywhere.  no squeals.  maybe i was just lucky.    it sounds like the miller cap thing is the way to go though.  if i have it right, they are an easy addition to my existing layouts.  as i understand it, 100-220pF caps gate to source on Q1, Q3, and Q4?  or is it gate to ground?  that would be harder.

Thanks for your work on your site. some good stuff there as well as some nice layouts.

thanks for noticing!  most folks are just interested in layouts. 

i am enjoying myself writing up my understanding of components as my understanding expands.  i am almost finished my capacitor section.  i still have to write up the math and i have been toying with various ways to put that up.  i think i have settled on small pdf files in html frames.  i've been putting fractions into special little html tables, but for integrals and exponentials i think i have to give up on html and mathml is just not universal enough yet.  so it looks like it's going to be pdf.  even fewer will venture into the math sections but i am having fun. 

all the best, gm

[John Lyons]

The DB miller caps that I have used are gate to source. Which is sort of a round about gate to ground, they have to go through the source resistor and caps to get to ground. I think that gate to ground would really knock out a good chunk of high end. I used 220pf caps on Q1, 2 and 4. Since the miller caps tame the very high end it would be interesting to try lower values and see what the difference is. More high end I guess. Seems pretty balanced with 220pf to me though.

Q3 is a cold biased clipper with that 3.9K unbypassed source resistor. In the soldano/dual rectifier/Peavey5150 (all based on the Soldano super lead overdrive) the value is 39K! or there abouts. I have been meaning to try a 25K pot in this position but haven't yet. I'm not sure why 3.9k was chosen as it's no where near the original value, unless it was a typo and no one caught it...I have not heard mention of the reason for the lower value. I'm not sure that adding a miller cap to Q3 would do much. Seems to work well without it there at least.

Did you put in a voltage divider or did you just not put in any tone controls? The Fender/marshall/vox tone stack takes away a good amount of gain. Since it's last in the line your probably has a lot of volume on tap. ?

John

[gaussmarkov]

The DB miller caps that I have used are gate to source. Which is sort of a round about gate to ground, they have to go through the source resistor and caps to get to ground. I think that gate to ground would really knock out a good chunk of high end. I used 220pf caps on Q1, 2 and 4. Since the miller caps tame the very high end it would be interesting to try lower values and see what the difference is. More high end I guess. Seems pretty balanced with 220pf to me though.

Q3 is a cold biased clipper with that 3.9K unbypassed source resistor. In the soldano/dual rectifier/Peavey5150 (all based on the Soldano super lead overdrive) the value is 39K! or there abouts. I have been meaning to try a 25K pot in this position but haven't yet. I'm not sure why 3.9k was chosen as it's no where near the original value, unless it was a typo and no one caught it...I have not heard mention of the reason for the lower value. I'm not sure that adding a miller cap to Q3 would do much. Seems to work well without it there at least.

thanks for these comments.   if you don't mind explaining, what does "cold biased" mean?  or maybe a reference?

Did you put in a voltage divider or did you just not put in any tone controls? The Fender/marshall/vox tone stack takes away a good amount of gain. Since it's last in the line your probably has a lot of volume on tap. ?

i followed martymart's first build as he described it here: Dr Boogey ... debugged and great ! there's a 27nF coupling cap followed by two identical low pass filters (15K/2.2nF) and a 100K volume pot.  Marty described it as runoffgroove sim-style.  although he had an eq section after the input buffer, Doug Hammond also did something similar with his Meteor.

cheers, gm

[John Lyons]

Cold biased is literally biasing a tube triode or FET closer to cut off (or in this case big time cutoff!) The larger the resistance to ground the colder the bias. Kinf of like biasing it to be clean and then way past that up until it serves as a clipping stage. Severve asymetrical clipping to be exact. But since the value is 3.9K instead of the stock 39K It's not taken as far as in the tube cousins....
Biasing warmer (biasing to 1/2 supply voltage) is going to give you more saturation and a warmer rounder tone.
The "biasing" in these FET circuits is a little different though because they are "biased" with series resistance at the drain trimmer unlike tube amps.
I would think that the value of the source resistor would behave the same as in the tube amps though...gotta try that 25K or so pot in place of the 3.9k to see what's going on. It would be great if that value could be scaled down and get even more low gain settings from the DB. The pedal really still has a good amount of crunch even at low gain settings. Q3 is the main reason for this I think. At 1.5k I would think the gain would clear up a good bit. Great low gain and high gain on tap would make this one very versatile. ANother knob though!!!!

The tone stack less version is similar to the BSIAB2 Low Pass Filter.
In that thread marty omitted Q5 which is a "cathode follower" or in this case a source follower which lowers the impedance of the circuit in order to drive the tone stack better. Since the tone stack isn't used you can just take the output from Q4's drain and to the LPF and volume pot. The Volume pot is 100k as well which is fine since the impedance is lower...

John



John

[gaussmarkov]

super info john!  thanks again.

re marty's version, i figured that Q5 was for driving the tone stack.  it caused me to wonder about the choice between such "driving" and "recovering," as in a transistor after the tone section, like in a tubescreamer.

and all of this has also caused me to realize that in my haste, i left a 1M pot on the tonestackless version rather than putting in the 100K.  i'd better go fix that.   

cheers, gm