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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Tue Mar 31, 2009 9:29 am Post subject:
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Hi,
Sorry to answer you wiyh a question, but I 've seen on another thread that you 've built 808 drum modules using http://xlargex.xl.funpic.de/ schematics.
I am preparing to build the bd, sd and clap modules, but I 've noticed that on the 'modifications' page the values for the potentiometers added are different from the same ones indicated on the PCB/Layouts page. For example, on the mod page, for 'Snappy filter' (Snare Drum) I got a 22K Log potentiometer, but on the PCB/Layouts page I got a 4.7KLog one.
The same problem on Tune osc1 where I got 2.2MLog and also 1MLog.
Can you remember wich value have you choosed for this controls?
thanks,
tommi _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Tue Mar 31, 2009 9:45 am Post subject:
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I'm pretty sure I went with the values listed on the "modifications" page. I don't think the original schematics illustrate any of the modifications, so it would be my guess that those part values are from the original circuit, and the ones on the "modifications" page are alternate values. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Tue Mar 31, 2009 12:10 pm Post subject:
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I can double check which pot I used when I get home. I couldn't say positively at this point.
Probably a much more reliable reference is the Midibox 808 bill-of-materials available at http://www.eight-oh-eight.org. It won't have info on the microLARGE mods, but it will have all the correct parts values.
Also, be sure to check the build threads on that site -- There is some essential information on the noise source and clap circuits. I've made the changes suggested in these threads and my clap and noise source sound way better.
Another note: on the 808 SD PCB, a power trace is missing for one of the dual op-amps. Make sure both op-amps are getting +V and -V power to the right pins. There will be problems with output level if you don't do this. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Tue Mar 31, 2009 2:46 pm Post subject:
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Ok, thanks for the precious information about the missing trace. There will be a trouble less at the building time.
I 've seen that link about the 808's construction and now I 'll check it for sure.
thanks,
tommi _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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Sebo
Joined: Apr 27, 2007 Posts: 564 Location: Argentina
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Posted: Tue Mar 31, 2009 7:28 pm Post subject:
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creatorlars wrote: | Also, be sure to check the build threads on that site -- There is some essential information on the noise source and clap circuits. I've made the changes suggested in these threads and my clap and noise source sound way better. |
I can't find any info about improving the clap and noise at the eight-oh-eight
forum, could you post the links to that posts.
Thank you. _________________ Sebo
---------------------------------------
My Music:
https://www.facebook.com/cosaquitos/ |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
Audio files: 4
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Tue Mar 31, 2009 7:36 pm Post subject:
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Quote: | Ok, thanks for the precious information about the missing trace. There will be a trouble less at the building time. |
No problem! Please let me know how things go. I've built BD, SD, CP & CB from the 808 layouts and have the rest etched -- I'll be finishing them all soon since I just finished a new panel for all the 808 stuff. So please let me know if you have any notes... |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Wed Apr 01, 2009 3:51 pm Post subject:
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I am planning to add a noise input jack on SD and Clap panels, so that I con use my noise module (MFOS cornucopia, wich is the module I am building at the moment), or any other source to experiment.
At the present time I 've just ordered the PCBs and I have not yet made the order of components, big order since is for six modules and a new wooden rack. I'll post any news.
cheers,
t _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Wed Apr 01, 2009 4:29 pm Post subject:
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Cool! I did the same thing with the noise input, except at the moment it's just implemented as send/receive jacks for the White Noise and Pink Noise outputs. So I could use alternative noise sources or easily send the noise through a filter or FX chain. I have the Noise Cornucopia and a CGS Digital noise as well. We'll have to compare notes about various experiments. |
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Sebo
Joined: Apr 27, 2007 Posts: 564 Location: Argentina
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Posted: Wed Apr 01, 2009 6:02 pm Post subject:
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Thanks creatorlars!!!
I found the thread!
I have my 808 clone half finished for a while, now I'm finishing the first batch
of modules of my modular, once done I will continue with it.
I etched the 3 big microLARGE PCBs (not the individual ones), and populated
almost all components. I'm missing some capacitors, all pots, the wiring, and the case. _________________ Sebo
---------------------------------------
My Music:
https://www.facebook.com/cosaquitos/ |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Thu Apr 02, 2009 7:58 am Post subject:
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Quote: | I etched the 3 big microLARGE PCBs |
I kind of wish I had done that... was wanting to make them more modular, but then decided to use the accent circuit and put them all on one big panel. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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etaoin
Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL
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Posted: Mon Apr 06, 2009 8:03 am Post subject:
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creatorlars wrote: | but it will have all the correct parts values |
Note though that there isn't such a thing as "correct parts". Roland themselves made several modifications to the 808 during its lifespan, as listed in the service notes in the "design changes and improvements" section.
So parts will only be "correct" referenced to specific serial numbers. _________________ http://www.casia.org/modular/ |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Fri Apr 17, 2009 7:45 am Post subject:
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Quote: | I am thinking to simply bypass the and gate in order to have just one trigger input. What do you think? |
Two ways to do this -- 1) just short the trigger & accent inputs together -- then the "accent" will depend on the level of the trigger. or 2) just connect accent to +15V. Since it's an AND gate, a constant voltage at Accent is fine.
Or for a "quick and dirty" accent control, you could connect a pot between +15V, Accent In, & Ground to get 0-15V at the accent input.
For my purposes with this new panel, all modules are connected to an accent bus that is a clone of the 808 Accent circuitry. I think it sits at 5V and when triggered, rises to whatever you have Accent Level set to (somewhere between 5 and 15.) I wanted a way to voltage control the accent level by basically just summing an external voltage with the 5-15V voltage coming out of the Accent pot. Looks like an op-amp summer is the way I'm going to go. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Fri Apr 17, 2009 8:11 am Post subject:
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Right, thanks. I think I 'll go with the first option because the sequencer I planned to use with the modules have the accent on trigger outs. Also, the trigger level is adjustable from 0..1V to 0..10V. I hope this last trigger voltage is enough for 808 clones. _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Fri Apr 17, 2009 8:48 am Post subject:
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The 808 voices respond to 5-15V. You could add +5V to your 0-10V triggers at the module inputs, somehow maybe?
Or send the trigger to the trigger input, but add it to +5V when it goes into the Accent input...
Out of curiosity, which sequencer are you using? |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Mon Apr 20, 2009 6:44 am Post subject:
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Quote: | I could not figure out how to sum +5V to the max. trigger level of this sequencer (10V - I believe this is when the accent is set to high on the seq01). |
Well I guess you'd send the unconditioned trigger to "Trigger In" and then to an op-amp which adds +5V to the signal. The output of the op-amp would go to "Accent In" providing 5-15V. That should do it, but then you've got the problem that the "Trigger In" pulse may be too weak to actually fire the drum at lower voltage levels (so maybe from 0-4V or something you don't hear the drum) -- then you're back to the beginning, and still losing some accent "resolution". You could maybe tweak resistors at the Trigger Input to make sure even very low-voltage triggers would still fire the drum.
I doubt your 808 circuits will sound the same on +/-12V... it is very specific drum circuitry and I can't imagine that it wouldn't affect the circuit... someone smarter than I may know better, though. In any case, it can't hurt to try... but if you want it to sound like a real clone, I'd go with +/-15V. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Mon Apr 20, 2009 8:03 am Post subject:
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Well, I built the 808BD last saturday and when I first tested it the 'sonic' part of the signal was missing, There was only the 'impact' portion. A sound like 'tick' or 'toc'. And the controls like decay, xtra decay, tune and envelope were ther with no effect on the sound, of course.
But, after some manipulation of the board I realized that one of the bypass caps were faulty... I changed it and... BOOOOM!
I tried feeding this module on both +/-12 and +/-15V and I don't see any difference, so I'll go with +/-12 wich is ok.
Weird things: xtra decay does something like resonating from 3 o' clock.
Is it the same for you?
Next step: 808 SD
Cheers,
tommi
About the trigger/accent: For the moment I tied them toghether and I 'll see what will be the effect with a variable trigger like the one of the seq01... _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Mon Apr 20, 2009 9:05 am Post subject:
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Glad to hear you got it working!!! I'm jealous, I am in the process of repaneling mine, still - and haven't had it in the system for several months. I miss it.
Yes, Xtra decay behaves in a rather bizarre manner. You can get the bass drum to self oscillate indefinitely. I did a drone track with self-resonating 808 BD as the only sound source once. |
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tommi
Joined: Dec 05, 2007 Posts: 247 Location: Italy
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Posted: Mon Apr 20, 2009 9:30 am Post subject:
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Quote: | Yes, Xtra decay behaves in a rather bizarre manner. You can get the bass drum to self oscillate indefinitely. I did a drone track with self-resonating 808 BD as the only sound source once. |
Great! And what about the envelope? It seems to me that on the full clockwise position it behaves in a strange fashion too: like inserting a pause between the impact sound and the boom, and changing the character of the impact sound itself...
Anyway, I like those features that gives more personality to the 808 bd. I just want to be sure that everything it's allright.
Going to the Snare, I tied the positive rail to the +V in of the tl072 - thanks for your advice !
tommi _________________ http://soundcloud.com/mister-vommi
http://tideofsound.net |
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creatorlars
Joined: Nov 26, 2007 Posts: 524 Location: Denton, TX
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Posted: Mon Apr 20, 2009 9:51 am Post subject:
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I can definitely confirm similar behavior with the envelope as well. Wild, huh?! I'm adding some Vactrol-based CV to the tuning on mine -- CV over the XTra Decay would be crazy too, I bet. |
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