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 Forum index » DIY Hardware and Software » Thomas Henry designs
The Thomas Henry Mega Percussive Synthesizer
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oneoff



Joined: Nov 23, 2008
Posts: 43

PostPosted: Sun Jun 27, 2010 10:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

sure,
more pics from this process in my blog:

http://noisedesign.blogspot.com/2010/06/thomas-henry-mega-percussive-synth-my_01.html
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jumunius



Joined: Apr 19, 2010
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PostPosted: Wed Jul 14, 2010 4:31 pm    Post subject: snappier decay? Reply with quote  Mark this post and the followings unread

Hi,

So I finally have powered up my MPS and it appears to be functioning, albeit with a little troubleshooting left. Two questions for the moment:

1) I notice is that I find the decay a little long for my taste, particularly on the noise and shell. I am using 1Meg Audio Taper per Bugbrand's diagram, which should help, yet I find myself getting the most use out of the first third of the pot, and wishing I had more control in the shortest range. Any suggested mod? Lower value for the respective timing caps perhaps? (And that would be C22 and C28?) A lower value of log taper pot (100k, 500k)?

2) J20 -- what's with the AGnd and DGnd? Is there a difference? I have them both plugged into the power unit's ground at present.

Thanks in advance!

-Jim
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kkissinger



Joined: Mar 28, 2006
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PostPosted: Thu Jul 15, 2010 10:24 am    Post subject: Re: snappier decay? Reply with quote  Mark this post and the followings unread

jumunius wrote:
1) I notice is that I find the decay a little long for my taste, particularly on the noise and shell. I am using 1Meg Audio Taper per Bugbrand's diagram, which should help, yet I find myself getting the most use out of the first third of the pot, and wishing I had more control in the shortest range. Any suggested mod? Lower value for the respective timing caps perhaps? (And that would be C22 and C28?) A lower value of log taper pot (100k, 500k)?


I've just connected fixed resistors across the Delay pots -- I'm still messing with the values to find out what I like the best. Also, I find the decay to be too short when the pots are turned to the far left -- So, I'm messing with this. I think I will leave the capacitor as is and just mess with the resistances.

jumunius wrote:
2) J20 -- what's with the AGnd and DGnd? Is there a difference? I have them both plugged into the power unit's ground at present.


If your synth has separate analog and digital grounds, then you use them as such. If your synth has only one ground (as does mine) then you can just hook both grounds to your ground.

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jumunius



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PostPosted: Sat Jul 17, 2010 7:26 pm    Post subject: Re: snappier decay? Reply with quote  Mark this post and the followings unread

kkissinger wrote:
I've just connected fixed resistors across the Delay pots -- I'm still messing with the values to find out what I like the best. Also, I find the decay to be too short when the pots are turned to the far left -- So, I'm messing with this. I think I will leave the capacitor as is and just mess with the resistances.


Thanks Kevin, that seems to help a bit. I find that 1M resistor (the highest value I have around) used this way is helpful, but maybe shortens the release too much at the far right. I'll try a higher value, or consider adding a switch to turn this resistor on or off.

On a related subject I was wondering if anyone has explored using CV to vary decays. Meaning, you could patch your kybd's CV out to the EG of the Noise, for example, such that the decay changes as you play different notes. This most obvious use would be for hi-hats, but I'm sure tons of sounds could benefit from this kind of control.

But I wonder if it's so easy to implement, since I don't see this feature in any drum module I'm aware of.
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kkissinger



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PostPosted: Sun Jul 18, 2010 12:03 am    Post subject: Re: snappier decay? Reply with quote  Mark this post and the followings unread

jumunius wrote:
kkissinger wrote:
I've just connected fixed resistors across the Delay pots -- I'm still messing with the values to find out what I like the best. Also, I find the decay to be too short when the pots are turned to the far left -- So, I'm messing with this. I think I will leave the capacitor as is and just mess with the resistances.


Thanks Kevin, that seems to help a bit. I find that 1M resistor (the highest value I have around) used this way is helpful, but maybe shortens the release too much at the far right. I'll try a higher value, or consider adding a switch to turn this resistor on or off.

On a related subject I was wondering if anyone has explored using CV to vary decays. Meaning, you could patch your kybd's CV out to the EG of the Noise, for example, such that the decay changes as you play different notes. This most obvious use would be for hi-hats, but I'm sure tons of sounds could benefit from this kind of control.

But I wonder if it's so easy to implement, since I don't see this feature in any drum module I'm aware of.


You could likely implement CV of the decay time with a vactrol.

Resistors R12, R13, and R15 are 1000 ohms and control the minimum decay time. A larger value would lengthen the minimum decay time.

Incidentally, I added pitch CV in two places:

1) A 100K ohm resistor at the junction of R64 and R65 to control Noise Filter cutoff frequency

2) A 100K ohm resistor at the junction of R68 and R69 to control the Impact Frequency. *

* The 100K value does not produce 1v/octave tracking -- a 50K value may get a little closer to 1v/octave tracking -- though I haven't tried this. I'm not really concerned about 1v/8ve tracking on this module. I added two additional jacks for the noise and impact cv's.

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jumunius



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PostPosted: Mon Jul 19, 2010 10:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Vactrols eh? Yeah, I suppose that makes sense, since I would want to be varying resistance. (Sorry, I'm still catching up...) Well, that sounds like something to try with MPS board number 2.

Now that I've troubleshot enough to have a working unit, I might tweak a bit but beyond that I feel like I should thank my lucky stars and move on to the backlog of boards that are awaiting wires.

Anyways, good thought for the future...
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Eraser127



Joined: Apr 20, 2010
Posts: 16
Location: Dordrecht, The Netherlands

PostPosted: Mon Jul 19, 2010 11:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Yay, a engineers@work midi-to-trigger print is on it's way. Intergrating the MPS in my midi setup (don't have other trigger equipment besides a DR-220E) at last
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jumunius



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PostPosted: Mon Jul 19, 2010 1:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

Eraser127 wrote:
Yay, a engineers@work midi-to-trigger print is on it's way. Intergrating the MPS in my midi setup (don't have other trigger equipment besides a DR-220E) at last


Ooh, that's handy! I just got a Papareil Midi2CV board, but for my work-in-progress modular drum machine, this Engineers@Work board seems like an excellent addition (and comes built!?!?!). I really really love the idea of a GM drum layout with 23 CV outs.

Obviously this comes with the downside of not having much in the way of CV for the Shell Pitch etc, but I can use my Papareil when I need that.
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Eraser127



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PostPosted: Tue Jul 20, 2010 8:32 am    Post subject: Reply with quote  Mark this post and the followings unread

It comes completely build indeed. For more CV this may not be the best option but i'll use it just for layering with other bassdrums for now
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Eraser127



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PostPosted: Sat Jul 24, 2010 4:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Whoohoo cheers cheers cheers My trigger interface has come in and works (ordered it from http://www.engineersatwork.nl/catalo...roducts_id/536), made an extra switch behind the MPS input so I can trigger it via midi or trig-out from another device.

on the left of the photo you see the interface triggered by my AN1X thru midi, in the corner of the MPS the switch and on the right the DR-220E that triggers the MPS thru trig-out. Now I can finally search for a suitable case although I like this one as well. Smile

And put the print in the box, don't mind the tilted pots, that's because of the cardboard


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loydb



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PostPosted: Sat Jul 24, 2010 7:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Love the case Smile
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mosc
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PostPosted: Tue Aug 03, 2010 6:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

Congrats, Eraser127!
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defex



Joined: Jun 27, 2008
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Location: Toronto, canada

PostPosted: Fri Aug 06, 2010 6:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

quick question:

in the BOM it says jacks NO and NC does that mean jacks with a built in switch for nomalling other inputs? I am building a modular which this will be part of, (at least one for now, probably 3 or 4) and have plenty of the jacks with built in switch which is broken when the plug is inserted.

Also i can not find a complete schematic anywhere which matches the components in the BOM to the actual values (sure i would just solder them in by the BOM, but i like to be sure).

nice little board by the way is amazing its so packed with options!
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jumunius



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PostPosted: Tue Aug 31, 2010 9:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, I know that mods to the MPS are discouraged, but what about an External Noise Source input. How hard would that be. Anyone tried it and have any success?
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kkissinger



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PostPosted: Wed Sep 01, 2010 5:41 am    Post subject: Re: snappier decay? Reply with quote  Mark this post and the followings unread

kkissinger wrote:
Incidentally, I added pitch CV in two places:

1) A 100K ohm resistor at the junction of R64 and R65 to control Noise Filter cutoff frequency

2) A 100K ohm resistor at the junction of R68 and R69 to control the Impact Frequency. *

* The 100K value does not produce 1v/octave tracking -- a 50K value may get a little closer to 1v/octave tracking -- though I haven't tried this. I'm not really concerned about 1v/8ve tracking on this module. I added two additional jacks for the noise and impact cv's.


You may want to consider these mods -- you could patch noise to them and, depending on the amplitude of the noise, would produce everything from pitched noise to virtually unpitched noise.

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jumunius



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PostPosted: Wed Sep 01, 2010 8:20 am    Post subject: Reply with quote  Mark this post and the followings unread

[quote="kkissinger"]
kkissinger wrote:
Incidentally, I added pitch CV in two places:


Cool, thanks Kevin. I remember reading somewhere that Thomas was concerned about "large or negative" voltages being used for CV and blowing an IC -- is that an issue here? Anything I'd want to avoid patching in?
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kkissinger



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PostPosted: Wed Sep 01, 2010 9:06 am    Post subject: Reply with quote  Mark this post and the followings unread

jumunius wrote:
kkissinger wrote:
Incidentally, I added pitch CV in two places:


Cool, thanks Kevin. I remember reading somewhere that Thomas was concerned about "large or negative" voltages being used for CV and blowing an IC -- is that an issue here? Anything I'd want to avoid patching in?


Those nodes appear to be ok -- note that they are fed from the front panel control that swings to 15v. I haven't blown anything from these mods... but I say this with the disclaimer that your results may vary. Smile

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Eraser127



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PostPosted: Sun Oct 10, 2010 6:13 am    Post subject: Reply with quote  Mark this post and the followings unread

And we've made some progress: the frontpanel is designed

See the attachement below

Right now I'm finding out where to buy the 19"rack but it'll be probably from this site http://www.modushop.biz/ecommerce/index_l2.php

And this set (Silver):

Posted Image, might have been reduced in size. Click Image to view fullscreen.

with this (mounting behind the front plate):

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I'm thinking about doing the decals with waterslide decal, I'll order some today and see how it will look on a test piece (because you need to spray varnish over the decal and I don't know if it's going to be pretty on a rack)


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janvanvolt



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PostPosted: Tue Nov 09, 2010 7:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

Fellow Chef's de le MPS: i need some help finishing up the MPS and i GREATLY appreciate any help.

Questions:
- I have two pots OSC1 LEV and NOISE in the shell section which i have no idea to wire out, same applies to the SEND/RECV and according SPST switch

- I have a wire which i don't know where to connect, in detail it is J17/6

Problems:
- Impact OSC Freq does not work, it's just a high pitch
- Noise RES has no effect.

Facts:
- It is creatorlars' panel version (see here)
- i used the MPS panel wiring from bugbrand mostly, but i have some issues and questions.

Pots wired / assignment
SHELL
OSC1 = RING FREQ
OSC1 LEV = ???
BALANCE = RING BAL
IMPACT= RING DEPTH
NOISE = ???
SWEEP = SWEEP
DECAY = DECAY
VC OSC2 = CV
OSC2 = PITCH
LEVEL = SHELL LEVEL

NOISE
VC CUTOFF=CV
CUTOFF= FILTER
RES = Q
SWEEP = SWEEP
DECAY = DECAY
LEVEL = NOISE LEVEL

IMPACT
SWEEP = SWEEP
DECAY = DECAY
OSC FREQ = PITCH
LEVEL = IMPACT LEVEL
MIX OUT = OUT

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jumunius



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PostPosted: Thu Nov 11, 2010 3:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi, I don't have my notes or build in front of me, but I can offer some clues. One immediate suggestion: go to page 19 of the thread and check out hendrixworkshops' graphic which adds titles all the external connections on the board. This should help clarify from a board perspective what is directed where.

One problem you are going to have is that Bugbrand and Creatorlars both use slightly modified panels, which don't match each other. Bugbrand's wiring diagram is really useful, but can be misleading when you don't catch where he's modded something. (I had some difficulties at first too!)

janvanvolt wrote:
I have a wire which i don't know where to connect, in detail it is J17/6


Per the graphic mentioned above, this is "volume top", presumably the leftmost lug of the Mix Out pot if viewed from the rear. I think Bugbrand's layout only used the synth-level out, where creatorlars' looks like he only used the audio-level out. I think this also causes you some confusion below.

janvanvolt wrote:

IMPACT
MIX OUT = OUT


So just to confirm, MIX OUT <> OUT. Or at least not quite. Be sure to run your Out jack through the pot, unless you WANT synth level. In that case, Mix Out pot becomes redundant, as does 17/6.

janvanvolt wrote:

SHELL
OSC1 = RING FREQ
OSC1 LEV = ???
BALANCE = RING BAL
IMPACT= RING DEPTH
NOISE = ???


Osc1 Lev is probably Ring Depth.

Impact and Noise -- I believe these are pots to control the level of CV to the Shell Osc (Osc2?) from the Impact and Noise sections. In the Thomas Henry design, you select whether to send impact or noise CV to the Shell with a SPDT, and you use the switch on a 1/4" jack to disconnect either when you patch an external CV in. It appears Creatorlars allows for simultaneous impact, noise and external CV, each at their own variable level, since banana jacks don't have switching functionality. (I don't know whether high simultaneous levels from all three CV sources would cause any problems to the circuit.)

Note that Bugbrand instead uses a DPDT configured such that you switch between all three inputs (impact, noise, or ext CV) to a single pot.

So:
OSC1 = RING FREQ
OSC1 LEV = RING DEPTH
BALANCE = RING BAL
IMPACT= (Impact CV portion of Bug's DPDT switch)
NOISE = (Noise CV portion of Bug's DPDT swtich)

Creatorlars Send/Receive jacks appear to send the impact portion of the signal (or maybe the whole signal?) out prior to the Mix pot. (See TH's MPS block diagram Send/Rcv Loops section for details.) The switch above there should interrupt the signal before it hits the MPS mixer. That way you aren't sending both the internal Impact signal AND and externally-processed Impact signal simultaneously.

Finally, take a moment with the graphics from hendrixworkshop, Bugbrand, Creatorlars, and finally of course, the MPS block diagram (and schematics) and when the diagrams disagree, figure out why -- this will lead you to some changes. You should especially rethink your wiring on Bugbrands' switches, because apart from the Noise Filter switch, I think all of Creatorlars' switches (or lack thereof) will be different.

I'm sure that a little rewiring will fix some of your audio issues. Very Happy
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janvanvolt



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PostPosted: Thu Nov 11, 2010 6:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the advice(s).

1) First, i fixed Impact OSC Freq, it was fed by the wrong voltage Smile
2) If i look at the larscreator panel, the IMPACT and NOISE POT in the "Shell" section make absolutely sense as this "replaces" the switch.

What would be helpful to have the original jumper descriptions which correspond to the original MPS PCB and neither the lars or bugbrand version.
Somehow i only got the 4 page pdf stuff.

So.. It's time to fiddle around with the wiring then.

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jumunius



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PostPosted: Thu Nov 11, 2010 8:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

janvanvolt wrote:
What would be helpful to have the original jumper descriptions which correspond to the original MPS PCB and neither the lars or bugbrand version. Somehow i only got the 4 page pdf stuff.


I don't know if you found that hendrixworkshop pdf, but now that I'm on my home computer I can repost for you. It wasn't included in the official docs, it's just something somebody helpful put together!

Glad to hear things are starting to come together for you. I am in the middle of repaneling mine and fixing the last couple inconsistencies between the Bugbrand scheme and my own panel.

-Jim


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janvanvolt



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PostPosted: Fri Nov 12, 2010 6:57 am    Post subject: Reply with quote  Mark this post and the followings unread

It seems i now get the idea behind creatorlars panel.

You are right with regards to the IMPACT pot. I rewired this and i get the whole
idea now:

- You take the outputs from Impact and noise and feed it to the IMPACT/NOISE pot.
- From there you use a 4K7 passive mixer for each of those pot and mix it together to the CV switched lug, from the lug to the CV Control pot.

This is now working as expected.

To answer various J21 Questions:
I have an old PCB silkscreen copy here, so it is _

- J21-1 to 10K resistor then to R65 (left bottom, 4th Resistor from bottom)
- J21-2 to 10K resistor then to R69 ( 3rd part left of IC4)

Working like a charm now Smile Thanks for all the support.

I just tried it with GATE, but the real fun is with trigger, so i am trying it on with the Q960 Smile

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casperelectronics



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PostPosted: Thu Dec 30, 2010 9:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

finally built the MPS I order 2 years ago. cool unit and very easy to tweak (but be careful about burning out those darned LM13700 ICs!). I left a bunch of room on the right of the panel for adding stuff as it comes along.
Added input jack for each sound as well as a bus switch for each voice so that triggers can be shared. I may remove these and add a "trigger all" jack. not sure yet.
I added a second decay circuit in the impact section to control the amplitude decay (labeled ADCY). No need to add a sweep control for this since it will always sweep from max to min volume.

Did a bunch of range tweaking as well.
I saw some discussion of this a few posts back.
-I've decided to buffer the high and low ends of the impulse pitch pot with resistors to limit the range. on the pitch pot I added 10k to negative switched R57 (56k) for a 120k.
-changed some of the cap values. C20 from .1uF to .22uF for the for a longer impulse decay and a C22 from .22uF to 1uF for short noise decay.
-increased filter resonance by switching the 20k range resistor (R46) with a 1k.
- added larger buffer resistors by a few K ohms for the decay length.


Something I really like is that you can send multiple triggers into the same jack. then you can play with the sensitivity knob and get different strengths of triggering depending on when the two sources over lap. It works like the "accent" feature on lots of drum machines. I think I'm going to add a second trigger input, maybe with attenuation, for each voice to exploit this cool feature.


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casperelectronics



Joined: Feb 13, 2008
Posts: 23
Location: Troy Ny usa

PostPosted: Thu Dec 30, 2010 9:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

casperelectronics wrote:
C22 from .22uF to 1uF for short noise decay.


oops. I meant I switched C22 from 2.2uF to 1uF for a shorter noise decay.
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