Black Arts Toneworks - Boneshaker [traced]

[modman]

I'd like to see the DOD Boneshaker and Horizon Devices Precision Drive. The noise gate in the Precision Drive makes it particularly interesting to me
https://www.youtube.com/watch?v=WXUrSuTHbko
https://www.youtube.com/watch?v=ucI7e0j_Mfg

Here are some guts of the DOD Boneshaker...
TL074 and a TL072 is used.

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[modman]

Here are some guts of the DOD Boneshaker...

Awesome! could you get some detailed pics of the standoff boards as well?

Sure, no problem

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[jrfox92]

After having a look through this thread I drew up a schem for the Boneshaker (sans resistor/capacitor values).
(see below)
I'm 95% sure this is correct.

[EmmG]

Great start, thank you. From the descriptions, it seemed like a dod250 with a parametric 3 band eq before the gain stage and nothing more, but you say the highs come later.

[jrfox92]

Looks like I got the Freq and Level controls labeled backwards.
Here's the updated schem:

[jrfox92]

Really can't stand the inability to edit posts.

After another look through (and some peer review), I realized I didn't have the LED oriented properly and didn't connect pin 3 on the Mid Volume due to the trace being obscured by the pot's shadow in the gut shot image I worked from. Also, mid freq pin 3 was obscured, I just cracked it open and checked it with a meter, so that's fixed, too.

DOD Boneshaker Schem.png

[digitalzombie]

Out of curiosity why did you label your IC's w/ the suffix 'P'. In the photos they're quite clearly marked 'C'.

[marshmellow]

That is just Eagle's way of differentiating between packages (DIP, QFN, QFP, TSSOP, ...), nothing to do with the actual part. The suffix from the manufacturer is usually some kind of grading: temperature ranges, accuracy, etc.

[Bassburger]

Hi, are there values for the gyratorEQ? Just curious about, what freqanhebung and Qs they used.

[sonicboom1974]

Thanks for the ckt trace.

There have been several comments in the forums that say the EQ is pre dist. Cause if you crank the EQ it gets dirty. Your trace shows that the EQ is not pre dist.

[fuzzfiend]

I verified the circuit trace. Nice job jrfox92! Just to nit pick, the FREQ pots are 500K log and I think all the pots may have pins 1 & 3 reversed.

I've also read that the EQ is pre distortion, but the trace clearly shows that isn't the case. I think the distortion control adds diode clipping distortion. I suspect boosting the EQ levels overdrives that last TL074 op amp. Pretty nifty to have 2 different flavors of distortion!

I don't hear any difference in sound for the first half of travel for the Distortion and all the EQ Level pots- only after 12 o'clock do they seem to effect the tone. In addition, I don't hear any differences no matter what position for the Depth knob. Maybe it only effects frequencies below the bass E string?

[jrfox92]

I verified the circuit trace. Nice job jrfox92! Just to nit pick, the FREQ pots are 500K log and I think all the pots may have pins 1 & 3 reversed.

Did you test it with a meter?
It kinda makes sense since the codes are B103 56L2 and A504 56A1, so that's a good point.

I don't hear any difference in sound for the first half of travel for the Distortion and all the EQ Level pots- only after 12 o'clock do they seem to effect the tone. In addition, I don't hear any differences no matter what position for the Depth knob. Maybe it only effects frequencies below the bass E string?

That's why I did the cap mod on mine (though, I'd prefer balancing [where each cap is ~500nF rather than one is 1uF and one is 33nF] it as opposed to just switching out the caps).

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Here's the updated schem, also.

DOD Boneshaker Schem.png

[fuzzfiend]

Did you test it with a meter?
It kinda makes sense since the codes are B103 56L2 and A504 56A1, so that's a good point.

I didn't test with a meter. I just read the values from the side of the pots. Using other parametric EQ schematics for guidance (sabrotone, geofex, BYOC, etc), 10K just seemed too low.

That's why I did the cap mod on mine (though, I'd prefer balancing [where each cap is ~500nF rather than one is 1uF and one is 33nF] it as opposed to just switching out the caps).

Nice! I had no idea this was a known issue. Here's the link I found... https://www.talkbass.com/threads/npd-do ... 375/page-3
My guess is that the caps and DEPTH pot set the range, with C5 defining the high frequency and C5 in parallel with C6 defining the low frequency.

Now I wonder if there is another soldering mistake robbing the FREQ pots of half their adjustments.

[EddieTavares]

It looks like a modified infamous boss hm-2:

[rocket8810]

any word on when the values will be plugged into the schematic? i've been dying to draw up a layout for this monster.

[jrfox92]

any word on when the values will be plugged into the schematic? i've been dying to draw up a layout for this monster.

I'd say it's unlikely to happen since that would require individual removal of the capacitors (the resistors could probably be figured out with the codes, but I'd bet they're about the same as any other normal drive and paraeq circuit).
I'll get around to updating the resistor values someday, but for the time being I'd take note of online parametric eq schematics and something like a Voodoo Lab OD/Fulltone OCD for both resistor and capacitor values.

[audiohub]

Thanks for posting the schematics for this!
I just got one a few days ago...they were having a "special promotion" and selling these for $40 shipped, so I took a chance and ordered one to see if it would be useful.

I've also noticed that the frequency controls have almost no noticeable effect until they're turned past the 12:00-1:00 position, and was wondering why.
My best guess is that the pot taper might have something to do with it...the frequency pot is an audio taper (the level is a linear taper) and this may have been more effective as a linear or maybe a reverse taper audio pot.
The sweep ranges for each band are somewhat narrow, and none of the bands overlap in frequency which would have been nice for a more intense boost or closely spaced notches or peaks.
As it is, it seems like the effect is wasted until you get past this point on the rotation. It might have been an inventory mistake on behalf of DOD, as pots like these are almost always a custom order with a
large minimum purchase.

The distortion control also has a similar slow onset in it's taper, although I'm not exactly sure why. The Depth control cuts the lowest frequencies pre-distortion, and its operation is pretty much invisible for standard guitar, but is supposedly nice for down-tuned instruments and bass.

The distortion effect is pretty *meh*, and maybe substituting some different "magic" diodes or LEDs in this position might spice it up a bit.

For $40 it's a nicely made pedal that can probably be finnessed to suit my needs, thanks to your work in publishing this schematic, which cleared up a lot of questions for me!

[audiohub]

Here's the values for the three gyrator circuits.
I removed each of the caps and measured them out of circuit.
Actual measured values are shown.

Here's a link to a gyrator frequency calculator:
http://www.muzique.com/lab/gyrator.htm

I used the cap and resistor designators from this for the chart below, which shows min and max frequency and Q for each band.
You can use the calculator to redesign the bands if you want.
Also shown are the resistance values of the pot at different rotation points.
If you plug in the values, you can see that not much happens until after the 12:00 pot position, as noticed.
No overlap between bands, and the Q decreases as the frequency of each band increases.
Reducing the size of R1 will increase the overall frequency sweep.

BONESHAKER DATA

LOW".............................. MID.............................HI
C1. 770NF.........................150NF.......................37.2NF
C2. 37.5NF........................7.41NF.......................2.38NF
58hz/7.73Q.................. 298hz/7.58Q.............. 1055hz/8.63Q
200hz/2.21Q................ 1016hz/2.22Q............. 3600hz/2.53Q

R2. 470 ohm

R1. 47K - 547K ohm. (Freq Adj)

Pot Resistance at various "clock dial" points

7....... 419K
9........403K
11.......387K
12.......368K
1.........224K
3.........86K
5..........0

[Khas Evets]

In the HI eq, 37.2NF seems too high. Could it be 37.2PF (0.037NF) instead? That would maintain the ratio of around 50x between the two caps.

[audiohub]

Hi Khas:
Those are the measured values for my unit.

Check out the link to the gyrator calculator I included in my last post...it will let you play around with different values and see the results. You can even redesign each band to your specifications, which is what I did, widening the sweeps so that they overlapped more.

R1 adjusts from 47k (the fixed resistor) to 547k (that resistor in series with the frequency pot).