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Peake
Joined: Jun 29, 2007
Posts: 1113
Location: Loss Angeles
Audio files: 3
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 Posted: Thu Aug 14, 2008 11:32 pm Post subject:
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Nice to see mods replacing the LF13331!
(Still working on finishing my 292c) |
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fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
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| Posted: Fri Aug 15, 2008 7:22 am Post subject:
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that's good. and i think i will be going to build another one for myself...
| guitarfool wrote: | | fonik wrote: | | the resonnance option is not tested, yet. i am not sure if someone built it in yet. |
It's tested  I was going to build a classic LPG using an older layout, and yours came out right after I'd finished the panels. So I built my first one without the feedback.
I've since built a second one WITH the feedback option, and it is wonderful. Now I have to do a new panel, so if anyone wants a couple of Moog/Dotcom format panels for a classic LPG... 
Anyway, there is absolutely nothing wrong with the schematic or layout.
If yours works without the option (jumper between "A" amd "B" on JP1), then the switch is probably okay. In this configuration, JP2, R18 and P2 are not needed. For the resonance option, point "A" of JP1 is jumpered to point "A" of JP2, and point "B" of JP1 is jumpered to point "B" of JP2. Maximum resonance occurs when the wiper of P2 is at the R18 end of the pot. At the other end, feedback is unity and the circuit behaves exactly like one without the resonance option. I tried both of mine (the first one without the option) and the second one side by side in the same patch, and with the resonance set to minimum, they sounded identical. I hope to get a sound file up this weekend to demonstrate.
With the resonance control above about two thirds, it will self resonate.
The resonance control only affects the LP mode: it does nothing in Gate or Both modes.
I heartily recomend adding it |
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cheers,
matthias
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Big Boss at fonitronik
Tech Buddy at Random*Source |
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Funky40
Joined: Sep 24, 2005
Posts: 875
Location: Swiss
Audio files: 1
G2 patch files: 5
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| Posted: Fri Aug 15, 2008 2:03 pm Post subject:
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| neandrewthal wrote: | | Every single LPG I've seen has no CV attenuators. Is there just no need for them in the way it is typically used, or is everyone using external attenuators? |
my own drawing has three CV inputs and the Modul i built has 2 attenuators for CV.
But the behave of the pots is not 100% satisfaying ( maybe i took 100K and should be 10K )
there is a BIG ! need for multiple CV inputs AND for attenuators .( at least for me )
This File: http://funky40.podspot.de/post/16-visit-at-the-mars-zoo/
had not been possible without my new LPG.
It was made the first evening after the first tests, so it was somewhat the final testing for my new LPG. |
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Ilanode
Joined: Sep 14, 2007
Posts: 80
Location: Berlin/FRG
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| Posted: Sun Aug 17, 2008 9:41 am Post subject:
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| guitarfool wrote: | | fonik wrote: | | did i misunderstood his suggestions? can't see why. anyone? |
No. You did good |
Yes, you did. My 2nd LPG works just fine and the Res. dials in very nicely different to other LPGs I know. Thanks for the layout! |
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synthmonger
Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3
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synthmonger
Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3
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| Posted: Thu Aug 21, 2008 5:07 pm Post subject:
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| What does C5 and R5 do? |
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Ilanode
Joined: Sep 14, 2007
Posts: 80
Location: Berlin/FRG
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| Posted: Fri Aug 22, 2008 6:43 am Post subject:
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Serenadi posted the following explanation on a German forum: C5 and R5 make the input more sensitive to higher frequencies. AM will be a bit stronger which should solely noticable when connecting a VCO modulated by a slow LFO to the CV In. The sound should become a little brighter.
Hope that helps. |
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fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
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| Posted: Fri Aug 22, 2008 7:49 am Post subject:
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good to know the what. the how is just another quenstion (that i could not answer, though).
_________________
cheers,
matthias
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Big Boss at fonitronik
Tech Buddy at Random*Source |
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Serenadi
Joined: Jul 03, 2007
Posts: 89
Location: Germany
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| Posted: Fri Aug 22, 2008 8:33 am Post subject:
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| fonik wrote: | | ...the how is just another quenstion (that i could not answer, though). |
It's easy but for me it's not as easy to explain in english.
I'll try:
C5 and R5 are just wired parallel to R4, the main input resistor of the CV-input.
C5 functions as a highpass.
The easiest way to think of the function of a cap is to consider it as a frequency-dependant resistor.
The higher the frequency the lower its resistance.
So with higher frequencies of the modulation signal, think of a link instead of C5 (resistance=0).
The input resistor will be R5 parallel to R4, which gives a value of 82k.
At lower frequencies of the modulation signal, think of a break instead of C5 (resistance=infinite) - the input resistor is just R4 - 100k.
A little bit larger than 82k, so the sensitivity of the CV-input will be a bit larger at high frequencies.
Patch a VCO to the CV-Input and wobble its frequency from LFO range to higher audio frequency.
(e.g. with an lfo)
At LFO range, the modulation index is the same - with or without C5/R5.
But in the audio range, the index is a bit larger when C5/R5 are connected.
Hope someone could understand. 
Last edited by Serenadi on Sat Sep 27, 2008 1:31 am; edited 1 time in total |
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fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
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| Posted: Fri Aug 22, 2008 8:36 am Post subject:
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you did quite fine, serenadi. thank you a bunch for this good explanation...
_________________
cheers,
matthias
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Big Boss at fonitronik
Tech Buddy at Random*Source |
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Serenadi
Joined: Jul 03, 2007
Posts: 89
Location: Germany
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| Posted: Fri Aug 22, 2008 8:42 am Post subject:
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| you're welcome. |
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guitarfool
Joined: Feb 26, 2007
Posts: 161
Location: Maryland
Audio files: 8
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Luka
Joined: Jun 29, 2007
Posts: 1003
Location: Melb.
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| Posted: Wed Sep 17, 2008 10:05 pm Post subject:
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i am about to build a quad using this design. i am going to adapt it onto one board, so i have a few questions to everyone who has a set.
is it worth adding a summing amp for the cv in so i can add multiple cv ins per lpg?
is it possible to bump up the summed cv and then drop them down again post LED to enable negative voltages. what kind of setup would let me do this? considering im buildig a quad i was hoping to intergrate a DIP or something to handle them all at once. will this introduce cross talk?
sorry about trying to pry all this out of everyone, obviously im still getting to grips with circuit design so any tips would be most awesome
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problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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Funky40
Joined: Sep 24, 2005
Posts: 875
Location: Swiss
Audio files: 1
G2 patch files: 5
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| Posted: Thu Sep 18, 2008 5:06 am Post subject:
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| Luka wrote: | is it worth adding a summing amp for the cv in so i can add multiple cv ins per lpg?
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Yes !
i just added the input section without summing amp, but the lin/log characteristics of the attenuators seems to be a little to logarythmic to me.
I think i will add an OP amp input stage also for CV. It might give a better control over Gain and lin/log characteristics.
edit:
thanks Guitarfool for the Demo ! |
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Luka
Joined: Jun 29, 2007
Posts: 1003
Location: Melb.
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| Posted: Thu Sep 18, 2008 5:10 am Post subject:
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great thanks for the info funky
ive had this idea that the lpg would love complex cv patterns
having no hands on experience with this unit i was keen to hear someone tell me it was worthwhile
thanx
ok ill do some futher research onto whether it is worthwhile feeding it negative voltages
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problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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vtl5c3
Joined: Sep 08, 2006
Posts: 425
Location: PDX
Audio files: 13
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| Posted: Thu Sep 18, 2008 6:36 am Post subject:
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I built a quad LPG with single CV inputs. I used it for a gig about a month ago and regretted not having multiple control inputs. I ended up dedicating the CV ins for EG control, but I ended up wishing I could play with a quadrature LFO and Joystick without having to switch patchcords.
| Luka wrote: | i am about to build a quad using this design. i am going to adapt it onto one board, so i have a few questions to everyone who has a set.
is it worth adding a summing amp for the cv in so i can add multiple cv ins per lpg?
is it possible to bump up the summed cv and then drop them down again post LED to enable negative voltages. what kind of setup would let me do this? considering im buildig a quad i was hoping to intergrate a DIP or something to handle them all at once. will this introduce cross talk?
sorry about trying to pry all this out of everyone, obviously im still getting to grips with circuit design so any tips would be most awesome |
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djthomaswhite
Joined: Nov 22, 2007
Posts: 140
Location: Orange, CA
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neandrewthal
Joined: May 11, 2007
Posts: 672
Location: Canada
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| Posted: Thu Sep 18, 2008 8:40 pm Post subject:
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I'm down for a quad LPG with resonance
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" I went through quite a few trannies til I found one I liked" - Wild Zebra |
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fluxmonkey
Joined: Jun 24, 2005
Posts: 708
Location: cleve
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| Posted: Fri Sep 19, 2008 6:57 am Post subject:
Re: LPG with Resonance PCB's |
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| djthomaswhite wrote: | | I have PCB Express design for the PCB (attached image). If you would like to get together on a small run of PCB's let me know and maybe we can put together a "shared buy". For example, a run of 50 would result in PCB's that cost about $10 for double sided, solder masked with silk screen. Any interest? It has the Resonance mod built on and is selectable with jumpers. There extra resistor mod also has pads. |
absolutely! put me down for 8!
bbob
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www.fluxmonkey.com |
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vtl5c3
Joined: Sep 08, 2006
Posts: 425
Location: PDX
Audio files: 13
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| Posted: Fri Sep 19, 2008 8:02 am Post subject:
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I'd take a couple! Any chance the layout could be made to work with VTL5C4/2s?
Romeo |
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krisp14u
Joined: Nov 11, 2006
Posts: 206
Location: uk
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| Posted: Fri Sep 19, 2008 8:55 am Post subject:
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i would take 3 if thers a run
cheers
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Cheers
Paul Darlow
www.krisp1.com |
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bugfight
Joined: Aug 02, 2007
Posts: 188
Location: Arlington, TX USA
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| Posted: Fri Sep 19, 2008 9:17 am Post subject:
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akkk more temptation
if this happens, i'll take 4
gotta feed the queue.
ever hungry, all mighty queue... |
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Junk Rhythm
Joined: Jan 07, 2008
Posts: 81
Location: San Francisco, CA
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| Posted: Sat Sep 20, 2008 5:25 pm Post subject:
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| I'm in for at least 2. |
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Photon
Joined: Mar 22, 2005
Posts: 363
Location: Boston
Audio files: 1
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| Posted: Wed Oct 22, 2008 6:47 pm Post subject:
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does anyone have any tips for adjusting the trimmer? What should I be listening for?
Thanks |
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LektroiD
Joined: Aug 23, 2008
Posts: 1019
Location: Scottish Borders
Audio files: 2
G2 patch files: 2
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| Posted: Thu Oct 23, 2008 2:06 pm Post subject:
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If this is the same board as the one I ordered from djthomaswhite, I've made a massive boo boo! I ordered all the components as in the list:
http://electro-music.com/forum/download.php?id=14435
Cost me a fortune too!
Please tell me these are different boards  |
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