D*A*M: Grand Magnus Orbiter (incomplete trace), Tag Board Layout

It's a Tone Machine / Arbiter Doubler - let's get that out of the way up front. Here's the thread on the D*A*M forum for the Grand Magnus Orbiter

Rainy day project for me, as I already have a Tone Machine that I'm happy with.  Not sure I'd ever be up for a two-layer tagboard layout… The D*A*M Grand Magnus Orbiter is something special in that regard.

This is also an incomplete trace as the second tag board is not visible - which also happens to include the tone control. I'd be surprised if Dave Main didn't tweak it somehow.  Personally, I think a larger cap in the tone stack to increase mid-range might be a distinct possibility - not unlike tweaks made to his Fuzz Sounds for a beefier sound.

The only significant change I noticed on the top board is the 10u cap on the emitter of Q, so it's a bit hotter at the start.  Silicon diodes are used on the top board in the octave section, which usually provides better (or at least different) results to germanium.

I'm assuming that if anyone builds this, they'll be an experienced builder, so I've left a few things that I might normally include off the layout.

D*A*M GRAND MAGNUS ORBITER - TAG BOARD LAYOUT

Photo care of Reverb.  

Looks like 100k sustain pot

LTSPICE 

This is the difference with the 10uf cap on the emitter of Q1 - basically, things get square right from the start, and there's an increase in level and a slight change in the frequency response.

Now we see the response at the output - assuming stock values were used on the Grand Magnus Orbiter.  As mentioned earlier, I'd be surprised if this was left stock, and like the Big Muff, the Tone Machine tone control is easy to mod and shape to your taste.  A standard mod is to increase the size of the 3n3 capacitor to lift the mid scoop.  Even a small increase to 4n7 makes a difference.   Another mod is adding a 22k resistor after the 3n3 capacitor, which makes it much more like a BMP tone control and dramatically increases the scoop.

This is the bass and treble sides of the tone control.

 

And finally, an output trace.

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D*A*M: Super Bee SB-68, 0.15" Vero (incomplete trace)

The D*A*M Super Bee SB-68 was mentioned as something that had not been traced yet, which made me curious.  I looked at a few photos and found that there are two versions.  One with OC82s and one with OC78s.  Some very slight differences, but otherwise, a MKII Tone Bender cramped onto a smaller board to fit the enclosure.

I still haven't been able to spot the value of the electrolytic capacitors on the input and on the Attack pot. These should not make a significant difference to the sound.  

If you have any more info or disagree with the values shown, please let me know in the comments.  Components with a red outline are assumed based on other TBs.

 

D*A*M SUPER BEE SB-68 - VERO LAYOUTS

OC82 VERSION

• No 10n cap to ground on Q1 base

• 100k bias resistor on Q2 collector

•  8k2 / 560 ohm bias resistor combo on Q3

• The resistor hiding under the electrolytic near the output cap is most likely the same value as an Italian TB

 

OC78 VERSION

• 10n cap to ground on Q1 base

• 47k bias resistor on Q2 collector

• 8k2 / 1k bias resistor combo on Q3 collector

• There doesn't appear to be a resistor involved with the attack pot, like on the Italian TBs (none that can be seen anyway)

 

D*A*M: Fuzz Sound FS-77, Tag Board Layout

I couldn't find a layout for the FS-77 anywhere, but I did find some photos online, so I decided to try and trace it back in November 2020.  I thought I had it, but when I looked at it again recently, I noticed the input didn't look right.  The caps were the wrong way around for an input blend...  hmmm.  If it's not an input blend, what is it?

So I went looking for more information, and recently someone was kind enough to share some photos with me (you're a legend), which completed the picture - I was a bit lost without the additional photos, and had mistaken the blend pot for an input blend, which is not uncommon on D*A*M designs.

THE BONES OF THE FS-77

So what is the FS-77?  Like most Fuzz Sounds, it's a Tone Bender MKIII with tweaks.  

• The collector resistor on Q1 & Q2 is only 4k7, as opposed to 10k

• 4.7uf input cap, with a 10n to ground

• Usual 220pf cap across collector and case of Q1 is 47pf

• Sonically the biggest change is the tone & blend controls, which are based on a Big Muff tone stack.  The blend is a kind of a mid-range control, based on the same idea as the AMZ presence control.  The blend pot changes the high-pass filter cut-off, which forms one half go the BMP tone stack.

D*A*M FS-77 FUZZ SOUND SCHEMATIC

ASSUMPTIONS

There are some component values that I've not seen, all other values have been seen on photos.

• Fuzz, tone and volume have been assumed based on normal tone bender values used by D*A*M

• Initially I had a 25k pot for blend, but after testing it, I've landed on 50k. Try some different values, maybe you prefer a 25k - the 50k just has a slightly wider range.   Being a BMP tone control, it's easy enough to tune to your personal taste, even if the stock FS-77 values are a little unfamiliar.

• The 220n between the tone and volume might be a different value - looks the same as the 220n on the board, and is large enough to not impact the frequency response after the tone control

TONE CONTROL

Despite being a BMP based tone control, they're not even close to typical BMP values 

It does allow a mid hump, as well as a bit of a scoop on some settings.

Bass, low-pass filter

220k & 2.2n = 329hz

Treble, high-pass filter

25k pot:     10n cap & 1.5k - 26.5k = 600hz to 10.6khz sweep

50k pot:     10n cap & 1.5k - 51.5k = 300hz to 10.6khz sweep

LTspice - tone & blend swept in values from 1, 50 & 100% (50K blend pot)

ON THE BENCH 

It works...   it gives you some classics tone bender MKIII tones, and then some more modern sounds as a result of the tone control.  

The blend provides a nice sweep, and works well with the tone control.  There’s a lot of useable tones in there.  I prefer the 50k pot as you get more range.  

I ended up using a wider piece of tag board as I'm going for a landscape layout in the enclosure.

D*A*M FUZZ SOUND FS-77 - TAG BOARD LAYOUT

Note: NKT213 transistors also used

D*A*M FUZZ SOUND FS-77 - VIDEO DEMO

I believe this is the only video demo out there.  You get an idea of the sound, but the pedal stays on one setting throughout, so it doesn't provide any ideas on the range.