Author Topic: Magnum Opus - 3 channel Boneyard Ultra Mega Plus  (Read 628 times)

Willybomb

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Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« on: October 30, 2019, 07:13:25 AM »
Gudday all.  Here's Magnum Opus.  As Jörg Sprave would say, "Let me show you it's features, ha ha ha".

It's a Boneyard on the vero layout from Tagboard, and as can be hit and miss with this thing (even on vero), I was lucky enough not to have any squeal so it became a base for this build.  It was originally inspired by a video of the Keeley El Ray Dorado that has Bat46 (41?) as a second clipping option - but when you switch there's a volume drop so it's not something you set up on the fly.  That bugs me, so the original intention was just to do a gain/volume/diodes on a footswitch.  And then I got silly.

While I like the Boneyard/plexitone, I've always wanted more gain/saturation from it so I started looking at a lot of my fav drives.  The Crunchbox has hard clippers to ground, the Zendrive has a pretty elaborate set of clippers, the Valvestates have green/red leds in a back to back pair going to ground.  While I hate the OCD, I decided to use its' 2n7000s, and drives like the @T have multiple clippers to ground.

I removed the 68n tone cap/tone pot and replaced it with a bandaxall eq from Parasit.

So, it has:
OD1 - Symmetrical green LEDs (sounds great), no diodes, Zendrive clipping.  For some reason I couldn't get the Bats to sound good)
OD2 Low - Symmetrical red LEDs, no diodes, Zendrive clipping
OD2 High - Back to back red LEDs, no diodes, asymmetrical 1n4148s
Hard clipping - back to back 2n7000, red LEDs, Bat 46(41?)
Hard Trim - just a pot to control the amount of hard clipping.  Needs replacing as it's all bunched.  Maybe a different taper or size - edit, the 100kB has been replaced with a 10kA.  It's better, but it still seems to be either "flat out" or "not at all" with a pretty small area for adjustment.  Maybe something like the Turnabout's 10kC would be better.
Body - selects between 1uf, 1.4uf, 2uf as I felt 1u (the newer plexitone value was a bit low but 2.2 could be a bit high)
A bandaxall eq using Parasit's layout.

And... a master volume to finish it all off...

EDIT:  I wasn't getting unity when some of the hard clipping options was engaged with the other clipping in some cases.  LEDs were generally fine, but the other diodes took too much out of it.  I was going to add an external boost but then I had a lightbulb moment, remembering that the Boneyard/Plexitone had a switchable boost, so I removed a jumper and soldered a 330k across instead, leaving the boost engaged.  This gives me enough level for unity+ in all the options, meaning that the soft clippers only channels needed to have their volumes brought down, which is easy enough.  Problem solved.

« Last Edit: October 31, 2019, 04:33:50 AM by Willybomb »

Marshall Arts

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Re: Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« Reply #1 on: October 30, 2019, 08:02:47 AM »
Wow... that's a lot of... wires, LEDs, switches, diodes, pots, footswitches, vero boards. I cannot imagine operating this monster live, but I guess you will settle for a specific setting sooner or later ;-). Impressive work, I admire your patience.

mjg

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Re: Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« Reply #2 on: October 30, 2019, 03:02:58 PM »
I can always rely on you to go above and beyond with the knobs and switches. You haven't disappointed.  ;D

Nice work!

Willybomb

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Re: Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« Reply #3 on: October 30, 2019, 05:08:40 PM »
Quote
Wow... that's a lot of... wires, LEDs, switches, diodes, pots, footswitches, vero boards. I cannot imagine operating this monster live, but I guess you will settle for a specific setting sooner or later ;-). Impressive work, I admire your patience.

Thanks.  In all honesty, this circuit really seems to like high FV diodes in the feedback loop, and the LEDs are probably my favorites.  The zendrive clipping is nice too.  I can't believe that people don't use green LEDs more often as they sound so good.  There's a lot of volume drop between these and the other options, so somewhat ironically I've ended up with the same situation I was looking to avoid.  On the upside each channel has its' own volume so it's possible to mix and match clipping and levels between channels.

It was a good 3 or 4 nights of wiring, and I have no idea how much time I spent trying out different clippers in the feedback loop.  For some reason the timmy style 1n4148 arrangement sounded like arse, as did the Bats in any configuration.  Back to back was farty, a/symmetrical wasn't bad, but there always seemed to be some weird stuff going on with some clean signal blooming up underneath the dirt.

Quote
I can always rely on you to go above and beyond with the knobs and switches. You haven't disappointed

That's good to hear.  I usually get my wackiest ideas and solutions to what and how I'm going to implement things in the shower or while lying in bed.

gordo

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Re: Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« Reply #4 on: October 30, 2019, 05:38:45 PM »
Holy mudder a' gad that's cool.  I suffer from option anxiety but that's a nice contender for the mother of all drives.  You've reminded me that I need to spend more time at the breadboard...

Willybomb

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Re: Magnum Opus - 3 channel Boneyard Ultra Mega Plus
« Reply #5 on: December 26, 2019, 02:29:31 AM »
Ok, so I modified it a bit, and probably will continue to do so BUT:

I changed the Hard Trim to a 10kC.  Yeah, it works, but it's not that exciting.  Adding hard clipping sounds best when there's no clippers selected in the soft clipping.  I think a panner like the Drive3 would be a cool addition next time....

However, when I fixed the popping caused by switching the EQ trimpot I decided to tidy the wiring, and afterwards I had the dreaded Boneyard whine.  Clearly, something does not like being next to something else in this build as I did not have it in testing, nor when it was originally boxed up.  I stuck a buffer I had lying around in front, and that killed the squeal.  It's just a simple jfet buffer - you can see it taped to the side.

Anyway, might swap out the 1n4148 asymmetrical TS clipping for red LEDs, not sure about a/symmetrical yet, to switch between that, no clipping, and the back to back pair.