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slo
Joined: Feb 18, 2007
Posts: 204
Location: Victoria, BC
Audio files: 1
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 Posted: Mon Sep 03, 2007 8:15 am Post subject:
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| Quote: | i like the addition of the ac/dc swithches on the new layouts.
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Ok, so I'm dumb, can you explain the addition of this switch on a filter. I understand it on a mixer (Bypassing a cap to mix DC eg. control voltages) |
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Photon
Joined: Mar 22, 2005
Posts: 363
Location: Boston
Audio files: 1
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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Posted: Mon Sep 03, 2007 11:48 am Post subject:
TH-201 "Mankato" PCBs available
Subject description: Input Coupling Switches |
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| slo wrote: | | Quote: | i like the addition of the ac/dc swithches on the new layouts.
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Ok, so I'm dumb, can you explain the addition of this switch on a filter. I understand it on a mixer (Bypassing a cap to mix DC eg. control voltages) |
Yeah, you've got the reasoning right: AC coupling for processing audio, DC coupling for processing DC or very low frequency control voltages. Audio waveforms will sometimes have a slight DC bias or offset that makes them not perfectly symmetrical around 0V. This DC bias can result in a thump if a fast attack is used (this can happen with a VCF and/or a VCA). A DC bias can also change the results when several waves are mixed together.
The AC coupling cap does have an affect on the frequency response of the input. In most cases though, the cap is designed to cut frequencies below the audio range. In the Mankato however, the filter has a range that extends well into sub-audio territory. This allows processing DC or very low frequency control voltages as long as the coupling cap is taken out of the signal path.
On my prototype Mankie, I've set up the inputs so that there is no cap on the audio inputs and it seems to work just fine in most cases. The AC/DC coupling switches are a nice addition because of the "just in case" versatility they add, but you can leave them off if space is very tight.
Tim (tries to avoid processing DC voltages) Servo |
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SolderSmoke
Joined: May 21, 2007
Posts: 15
Location: Sweden
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| Posted: Mon Sep 10, 2007 4:37 am Post subject:
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| I´ve got my PCB, but I can´t find any schematic anywhere. Am I looking at the wrong place? |
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Coriolis
Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark
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| Posted: Mon Sep 10, 2007 7:50 am Post subject:
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Yeah Tim, you keep saying you'll mail me the docs, but where are they? 
C |
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Coriolis
Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark
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| Posted: Tue Sep 11, 2007 1:08 pm Post subject:
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Never mind - I see there's a BOM up on the Magsmoke site. Assuming there are no other docs to be had?
C |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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Posted: Tue Sep 11, 2007 2:22 pm Post subject:
TH-201 "Mankato" PCBs available
Subject description: Mankato build docs |
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| Coriolis wrote: | Never mind - I see there's a BOM up on the Magsmoke site. Assuming there are no other docs to be had?
C |
There are other docs, but we email those out. They are on their way to you as we speak. I'm still recovering from AH Cali, but hope to catch up on all the Magic Smoke requests / mailings / orders this week. Thanks to everybody for your patience.
You know, I thought I just had a few little things to do for AH Cali, and then Friday went until 3AM and Saturday turned into an all-nighter. Good thing I take my vitamins!
Tim (vitamins, a large Starbucks, and a couple of Pepsis) Servo |
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Coriolis
Joined: Apr 11, 2005
Posts: 616
Location: Stilling, Denmark
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| Posted: Tue Sep 11, 2007 11:32 pm Post subject:
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Just got the docs - thank you!
I only just realized you were attending that event, put two and two together and figured you'd be back soon... 
C |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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Posted: Wed Sep 12, 2007 1:58 am Post subject:
TH-201 "Mankato" PCBs available
Subject description: Mankato Docs |
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| Coriolis wrote: | Just got the docs - thank you!
I only just realized you were attending that event, put two and two together and figured you'd be back soon...
C |
No problem. Now get that soldering iron warmed up! 
BTW, AH Cali was a great little show. Spoke to Gino Robair (editor over at Electronic Musician Magazine), and had a great chat with Paul Schreiber (MOTM) about mechanical packaging and production techniques. Also got a demo of the new MOTM Cloud Generator by none other than Robert Rich. Wanted to talk to Dave Smith, but he had several people around him almost constantly, so I figured I wouldn't add to the crush. Also chatted briefly with Randal, Tom Arnold, Brandon Daniels (whose Minimoog I still have on loan, and to whom I forgot to give his Mankato PCB), and several others (I'm lousy with names, sorry about that). Also had a copy of State Machine's Thomas Henry VCO Chip Cookbook for people to check out, and copies of Thomas' AS21C, Making Music with the 566 and Drum Cookbook to look over. I didn't have my 566 VCOs ready yet (PCBs not back from the board house yet), but I threw together a basic little rack rig to show off a couple of Mankati and a few of Suit & Tie Guy Modules (including a zippy looking Mankato panel). All in all, a very fun event!
Tim (lousy with names, only slightly better with the smart a** comments) Servo |
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Photon
Joined: Mar 22, 2005
Posts: 363
Location: Boston
Audio files: 1
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| Posted: Wed Sep 12, 2007 4:47 am Post subject:
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Whats the optional resistor R2 (7.5K) for?
'Install for class A' doesn't clear anything up for me. 
Thanks! Sorry if this is clearly spelled out somewhere... |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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Posted: Wed Sep 12, 2007 9:30 am Post subject:
TH-201 "Mankato" PCBs available
Subject description: Class A |
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| Photon wrote: | Whats the optional resistor R2 (7.5K) for?
'Install for class A' doesn't clear anything up for me.
Thanks! Sorry if this is clearly spelled out somewhere... |
No problemo. Basically, the 2164 can be operated in either class A or AB mode. In an amplifier, this sets how the circuit is biased to limit the "crossover distortion" that can occur when an input signal goes from negative to positive (or vice-versa). There are many schools of thought on this, but in the Mankato circuit I've really seen (heard) no difference between the two modes. As Dave Brown points out on his most excellent Mankato page, it may be more noticeable when the 2164 is used as a VCA with lower line-level signals. You might want to experiment, but I've ended up leaving R2 off in my Mankati. BTW, here's Dave's page if you want to take a look at a seriously nice Mankato implementation:
http://www.modularsynthesis.com/magicsmoke/mse.htm
Scream out if you have any other questions!
Tim (Class Z operation) Servo |
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tomcat
Joined: Oct 14, 2005
Posts: 141
Location: earth
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| Posted: Wed Sep 12, 2007 4:51 pm Post subject:
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Dear Class Z operator 
Stupid question: The difference between the 4 or 8 pole configuration is just 4 jacks and some panel space more. Or did i overlook something?
Tom |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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Posted: Wed Sep 12, 2007 8:32 pm Post subject:
TH-201 "Mankato" PCBs available
Subject description: 4 pole vs. 8 pole poll |
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| tomcat wrote: | Dear Class Z operator
Stupid question: The difference between the 4 or 8 pole configuration is just 4 jacks and some panel space more. Or did i overlook something?
Tom |
Yup, you got it right. We were originally going to make two different PCBs, but it turned out to be much easier and cheaper to make one and simply use a different set of outputs. There has been some discussion earlier as to which outs to use if you only have space for four, but there are a couple of different ways to do it. The setup would primarily depend on if you wanted the Mankato to spend most of its time as a VCF or a VCLFO.
Tim (pole position) Servo |
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Peake
Joined: Jun 29, 2007
Posts: 1113
Location: Loss Angeles
Audio files: 3
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Posted: Wed Sep 12, 2007 10:13 pm Post subject:
Re: TH-201 "Mankato" PCBs available
Subject description: Class A |
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| Tim Servo wrote: | | Basically, the 2164 can be operated in either class A or AB mode. In an amplifier, this sets how the circuit is biased to limit the "crossover distortion" that can occur when an input signal goes from negative to positive (or vice-versa). There are many schools of thought on this, but in the Mankato circuit I've really seen (heard) no difference between the two modes. As Dave Brown points out on his most excellent Mankato page, it may be more noticeable when the 2164 is used as a VCA with lower line-level signals. |
Sorry for nudging in. The Mankato appears to be a very high quality circuit, so crossover distortion should be avoided if possible. There is likely almost none there, so the issue is likely close to moot, but in testing level-matched audio amplifiers (more critical than VCAs), one with 3% crossover distortion showed up as sounding awful, especially compared with the rest.
If you use the circuit as a VCA, I'd second the suggestion to use Class A mode, if that reduces the CD.
Cheers to everyone involved with this project. |
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endif
Joined: Jul 14, 2006
Posts: 138
Location: Reno, NV
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| Posted: Tue Sep 18, 2007 7:31 pm Post subject:
First final build |
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Okay. The Mankato will be my first final non-kit build.
(previous finishing experience = the Blacet VCO and Mult kits)
I have the PCB built out, and am just waiting on my SSM2164 from DigiKey.
I have a variety of templates to use in creating my panel, thanks to this magnificent forum. =D
I plan to use 1/8 inch clear lexan ($7 for a 24x36 sheet from Menards), which I will cut with a fine-blade jigsaw from a 3 space template I made, then use the template from this forum to drill out the holes.
With the Lexan, cut/drill careful and slow or she cracks. I built a test panel, and it is strong and nice.. once you get past the cutting and drilling. =] Used a file on the rough edges. Very easy to work with aside from the aforementioned brittleness under power tools.
Looking for suggestions opinions on a few things.
- How best to mount the PCB to the faceplate? I saw the awesome MOTM format example earlier in the thread used a 'stooge plate' to mount the PCB perpendicular to the panel. What is this stooge of which you speaks?
I've also seen people use standoffs, such as with the Harvestman Malgorithm, where the PCB is parallel to the panel, and the wires are sandwiched between the two. Just personal preference?
- Finishing.
I'm vascillating between two methods, interested in your thoughts.
One is simply printing out a design and sticking it on the inside of the clear panel, basically a reprint of the template I used to drill with.
The other is either leaving it clear or sanding the inside of the Lexan with ultra fine grit sandpaper to render it cloudy, and then finding some clear decals for labeling (on the outer face if I go for cloudy), then setting up some LED's on the inside of the rack. Bling bling.
I have a LOT of boards nearing completion on my little assembly line, I think around 15 at the moment, so your assistance with these questions will carry over to those projects as well.
Thanks in advance,
_________________
~ !J!
http://www.endif.org
http://www.crunchpod.com
http://www.myspace.com/endif |
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serenechaos
Joined: Aug 04, 2007
Posts: 13
Location: lost alamos
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| Posted: Tue Sep 18, 2007 7:42 pm Post subject:
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Are the 2164 chips still available, or unobtainium?
Thanx |
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davebr
Joined: Jun 09, 2007
Posts: 198
Location: portland, or
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| Posted: Tue Sep 18, 2007 10:18 pm Post subject:
Re: First final build |
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Stooge was the best!
Bracket information is at http://www.wiseguysynth.com/larry/bracket.htm
Larry did a great service by providing these brackets and they are no longer available from this site. I don't know if anyone else is selling them. There is a drawing available. I just make mine out of aluminum. It's soft enough that I can cut, drill, and bend it. I just leave the finish bare.
Bridechamber has a PCB bracket, somewhat similar. Don't know if it will work with the Mankato PCB dimensions.
http://www.bridechamber.com/parts/pcb_bracket.html
| ENDIF wrote: | How best to mount the PCB to the faceplate? I saw the awesome MOTM format example earlier in the thread used a 'stooge plate' to mount the PCB perpendicular to the panel. What is this stooge of which you speaks?
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Randaleem
Joined: May 17, 2007
Posts: 456
Location: Northern CA, USA
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| Posted: Wed Sep 19, 2007 12:02 am Post subject:
Re: First final build |
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| davebr wrote: | Stooge was the best!
Larry did a great service by providing these brackets and they are no longer available from this site. I don't know if anyone else is selling them. |
Hi,
Didn't Doug Wellington take over the making of the Stooge brackets along with the Stooge panels he is still making? (He's a member here, so you could send him a message to find out for sure the extent of what he's making these days.)
Agree, Yes. Larry H did many great things for the synth DIY community and is missed.
Kind Regards,
Randal |
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Randaleem
Joined: May 17, 2007
Posts: 456
Location: Northern CA, USA
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| Posted: Wed Sep 19, 2007 1:15 am Post subject:
Re: First final build |
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| ENDIF wrote: | Looking for suggestions opinions on a few things.
- How best to mount the PCB to the faceplate? ...
I've also seen people use standoffs... where the PCB is parallel to the panel, and the wires are sandwiched between the two. Just personal preference? |
It's all ultimately personal preference!
The simplest way to DIY is with a large PCB to make it easy to fit parts to and to also easy to solder them in place.
The simplest way to mount this PCB is with a couple angle brackets in the corners that affix to the front panel. PAIA modules were made this way for years; maybe they still are?
You can get these angle brackets for pennies from most any electronics supplier. They have one tapped leg and one thru hole leg. 4-40 is the typically used size.
It works well and has been used for many years. For a home-based synth you can't beat the price.
The three downsides of this approach are:
1) The depth of cabinet needed is greater (often MUCH greater!) than for modules designed with economy of space in mind. Look at Blacet modules compared to the Harvestman, Cwejman, Buchla, Serge, and those of most other mfrs.
2) The PCB is not well supported along its entire length and the "lever" that is created between the far end and the front panel can be a problem both before the module is installed; and after if/when the synth cabinet is moved. Even a short drop to a table top can impart many G's to a module unsupported. Now, most of the time for home synth's this isn't really a problem. But it's good to keep in mind if you see yourself doing any kind of performing where the synth you're making will need to be moved frequently.
3) It's harder to wire up the typical "flying wires" than with modern designs where the front panel controls are all (or mostly) fit to multiple PCB's. Have a look at Ken Stones newest designs to see the change in pcb layout technique he is using for the modules he is doing for sale as completed items. (Bananlogue and the Panther series. Also his newest synthacon? filter for DIY is in this format.)
The flat style (even with the flying wires, as in Serge panels) not only saves space; it should also minimise movement of the various parts during travel and therefore be more robust than an "L" mount technique. But with the advent and popularity of stooge style brackets, most of this benefit becomes academic IMO. Both methods will survive road trips if well handled. But the flat style will be smaller, probably lighter, and perhaps more easily accomodated in existing travel cases. So it still has the edge, IMO.
There are down sides to the flat style too.
1) Can be hard to make adjustments compared to the L, where everything is immediately accessible. (Especially when converting a modules designed for L-mounting to flat.)
2) Panel width can be adversely affected by pcb size needs. And an integrated design like the CGS filter mentioned above ties you into a specific panel layout. There are ways around this of course. but they can be a PITB. Not only layout, but part choice is affected similarly.
3) DIY flat panel layouts often have more hardware showing through the front panel. I've never been bothered by this personally; but it's plain to see that many guys disagree. Using the PEM style standoffs which don't show is an option but requires special tools. Others use FH thru screws as standoffs, and fill and paint afterwards to hide the hardware. (Which is a nice DIY method to trade time for money.)
4) the integrated multi-board approach can make it tough to replace a bad pot or switch or jack. Though this may lead one to install better parts at the outset!
Much of the answer is going to be determined by how you do your version of "DIY". If you make everything from scratch, you can do whatever you like. But if you're like the VAST majority; you will be using the output of others as the beginning of YOUR SDIY. So you will be guided by what they might have intended. Or you'll be working around it!
Either way, if you plan to build circuits using PCB's from a variety of suppliers; you'll see all different methods. And you'll either make several cases of differeing sizes; or you will have to fit each PCB "starting point" into your preferred format.
Point here is that it will be easier to accomodate this variety if you initially choose a larger format type like dotcom, MOTM, or even the seemingly growing element of Aries-inspired modules (with large panels and small jacks). Wiard and the Scott Stites KS01 are two examples.
| Quote: |
- Finishing. I'm vascillating between two methods, interested in your thoughts. I have a LOT of boards nearing completion on my little assembly line, I think around 15 at the moment, so your assistance with these questions will carry over to those projects as well.
Thanks in advance, |
My first modular in '77 had two "rows" of black acrylic. The modules were all on one of two panels, Serge like, with vertical white lines separating them. Modded cases with LED's weren't as prevalent then! (But we had christmas tree light color organs!)
I liked the look of that synth very much, and the black plastic panel was a big part of that. I made a "moog35" slant solid walnut case for it in woodshop, and the black panel with the aluminum turned knobs I made in metalshop contrasting the walnut was beautiful. Sadly now, Like so many others I sold it in my mid 20's.
But I have to say I won't ever use a plastic panel again, except as a see-through test of layout. (even that is now easier to do in SolidWorks or even FPE.) Plastic is just too flexible, too static prone, and too easily scratched.
If I were doing one these days, I'd probably try to find a kinko's type shop that did color printing on sign vinyl. The Gerber Edge printer was the leader in this a few years back. Doing it this way you get great graphics, easy adhesion to the panel, and the ability to replace (or update) a worn out graphic in the future. Downside is the softness of vinyl, and the way pot nuts will wrinkle it or paper or most other kinfds of overlays. Unfortunately most paints don't stick well to lexan. But you could engrave it and use a fill stick.
Your idea sounds nice; whichever of the two methods you end up with. I'd suggest trying both, or even a few different techniques.
Just as breadboarding the circuit is important; you'll be breadboarding the cabinet panels. Trying to figure it all out ahead of time can be a sad road to travel... (he says knowingly  )
With 15 modules to start from; you can easily determine what you like without spending too much time going down a wrong road.
Good Luck!
Randal |
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endif
Joined: Jul 14, 2006
Posts: 138
Location: Reno, NV
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| Posted: Wed Sep 19, 2007 11:42 am Post subject:
Dragons teeth.. |
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Always such great replies on this board! =D
I went the Bridechamber route, two CGS and two MFOS, plus some of their 1k tempcos, but will also experiment with off the shelf angle brakets and such.
More questions, of course, have now arisen from the answers, like dragons teeth..
- Plastic has static issues? Dang.
I just finished creating a mankato plate today from the aforementioned Lexan stock, and thought of a way to make it look nice: spraypaint the back of the panel, then carefully scratch in the markings and words, then backlight heavily with LED's....
...but if it's gonna kill my chips I'd rather take my chances working aluminum.
So is the Lexan a bad idea or no? Did your boards ever actually take damage from the static? I
- If I go to aluminum, what should I look out for, and does anyone have suggestions on where to source it from, and what thickness to get?
Thanks again,
_________________
~ !J!
http://www.endif.org
http://www.crunchpod.com
http://www.myspace.com/endif |
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Randaleem
Joined: May 17, 2007
Posts: 456
Location: Northern CA, USA
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| Posted: Wed Sep 19, 2007 9:58 pm Post subject:
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Before I reply more about general panel things in a Mankato PCB thread, a moderator question.
Should/can this OT be moved to a new thread?
Kind regards,
Randal |
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endif
Joined: Jul 14, 2006
Posts: 138
Location: Reno, NV
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nutoniom
Joined: May 24, 2008
Posts: 33
Location: montreal
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| Posted: Thu Jul 24, 2008 11:39 am Post subject:
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I have just received my Magic Smoke Mankato PCB, and all I can say is ...
WOW.
I think I need to order another one as I don't know if I'll be able to bring myself to put a hot iron to it. It's that nice.
Many thanks to Tim (I will go out of my way to please) Servo for the stellar service.
jf
_________________
beyond the atmosphere, there is no space, only time...
http://www.7161.com/css_artist.cfm?user=380 |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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| Posted: Fri Jul 25, 2008 11:25 am Post subject:
TH-201 "Mankato" PCBs available |
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Well Jf,
Of course you can buy another PCB if you want. They are suitable for framing However, I will say that the Mankato PCB looks even better with parts on it. Especially if you use 1% resistors (light blue bodies, a nice contrast with the PCB color), and blue trimmers. It ends up being a very colorful assembly.
Actually, Jf was VERY patient while we got a miscommunication miscue and moving all sorted out. I'm glad the PCB and all the parts got there, and that you're all set to go.
Tim (suitable for hanging) Servo |
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Sound
Joined: Jun 06, 2006
Posts: 842
Audio files: 1
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| Posted: Fri Oct 31, 2008 9:52 am Post subject:
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Hi,
I have noticed in the Mankato PCB there are two outs more, labeled as audio sum output and CV sum output.
Both are after the mixer op amp.
I think that is very useful and I want to to implement it in the front panel.
For example, the audio sum out, if in addition I put one switch before the resistor R4 I will have an independent mixer when I will use the Mankato as oscillator. As a filter I will be able to send the same mix signal to another Mankato ( I'm designing a dual Mankato) and process the same mix in a different way.
And with the CV sum out I will be able to control the two mankato with the same VC sum. Useful as a oscillators as well as a filters as well as osc+filter key track.
But my question is, If I split the VC, maybe I will lose amplitude? so I will lose precision?
Thanks. |
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