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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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 Posted: Fri Oct 28, 2011 5:24 am Post subject:
Is asking questions about TH's books ok?
Subject description: just thought id ask |
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Hi
I have a couple of queries about the Thomas HEnry books i just bought; Theyre a little over my head TBH, especially An ASforthe21Century.
Since theyre not free/everywhere, is it ok to ask here; got a bit confused in Drum Cookbook.
IVe got
Drum cookbook
3080 OTA
Analgue Synth 2st Century. Theyre great! will get the rest.
Also, what would be a good book between this level of complexity and Nicolas Collins, which is complteley aimed at noobs.
Cheers
Ben |
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jumunius
Joined: Apr 19, 2010
Posts: 330
Location: San Francisco, CA
Audio files: 13
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| Posted: Fri Oct 28, 2011 8:27 pm Post subject:
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Hi Ben,
I don't think there's any reason not to ask. If anything I'd think that discussion about the books would encourage more buyers of the books.
Of course, I presume that posting whole schematics or long sections of text might not be cool. Then again, some pieces of Drum Cookbook, for example, are used directly in TH projects with PCB offerings, with schematics that are widely available. I'm pretty sure Bass ++ and MPS use the same trigger and envelope circuitry as the Drum Cookbook describes.
I'm actually slowly finishing a schematic for a 3x percussion EG + attenuverting digital mixer module that I stripboarded. When done I plan to post it, and I only feel ok doing so because most sections of the schematics are lifted from freely available schematics designed by TH, MFOS, etc.
If anyone thinks this is a bad idea let me know -- I just plan to post a schematic, not sell PCBs to fund a yacht or anything. And of course I will credit the sources.
-Jim |
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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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| Posted: Tue Nov 01, 2011 10:09 am Post subject:
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Sorry Jim, i read this on my phone and thought id replied.
Yeah, thanks, i thought so, didnt want to upset anyone  Obviously wont scan entire things.
Ive got a ton to write so will have to wait, stuck at work now. Some things are making more sense after numerous reads.
Cheers, Ben |
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mark_olson
Joined: Oct 26, 2006
Posts: 177
Location: Lawrence, Kansas
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| Posted: Tue Nov 01, 2011 12:46 pm Post subject:
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I may be speaking out-of-turn here, but I cannot think of a better place to bring up any questions you might have. The author himself might even chime in with a little guidance!
Mark |
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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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| Posted: Sat Nov 05, 2011 1:19 pm Post subject:
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Cool, thanks.
Well I will do; I dont want to either ask something so ridiculously stupid that rereading it a couple of times wont help, or sounds like im trying to be clever...
But one question has really been bugging me;
trigger levels.
Ok, here goes.
First chapter;
Standards (!)
A trigger input is 5v positive, 1ms long. Cool.
Trigger conditioner
Outputs a 12v (...) pulse, 1ms long (erm...)
Guiro thing
Outputs a 15v pulse, 1ms long.
Admittedly he does state maybe a resistor divider may be required on the putput but ??? Why isnt it explicitly designed to acheive the standards he himself set at the outset ?
Whats the right/a good level to aim for? This sort of thing confuses the hell out of me honestly. 
My very limited knowledge which may be completely wrong, doesnt a res. divider just waste energy as heat? Down to ground?
Any clarification on this would be gratefully received.
I appreciate the books arent aimed at complete beginners, so im sorry if this is something i will need to figure out, but hence why i asked about asking in the first place!
Cheers, Ben |
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Mongo1
Joined: Aug 11, 2011
Posts: 392
Location: Raleigh NC
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| Posted: Sun Nov 06, 2011 4:44 pm Post subject:
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| Quote: | A trigger input is 5v positive, 1ms long. Cool.
Trigger conditioner
Outputs a 12v (...) pulse, 1ms long (erm...)
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I'm just guessing here, but when you specify an input level, you typically specify the LOWEST level that will work. If you look at TTL logic chips for example, everybody knows that TTL works at +5 and Gnd, but when you study the datasheets, you find that input levels are something like > 2.4 for a high, and < 1.2 for a low.
So it makes sense to say that a trigger input level is 5V, but then turn around and make something that outputs a trigger pulse use a much higher level.
You do the same thing with the trigger length. The spec says 1 mS, but you'd probably want to output something longer than that to make sure it works properly.
Gary |
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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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| Posted: Mon Nov 14, 2011 10:23 am Post subject:
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Sorry Gary, thought id replied, saw this on my phone a while back, and obviously didnt work.
Thanks !
That kind of makes other things make a bit more sense. Wouldnt a longer trigger mess up envelopes and stuff? I kind of thought it was a trigger on event.
Ill have to go trhu the books and post my other queries, using my phone is painful and internet a long way away from my books/lab/desk (!)
Cheers, Ben |
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Mongo1
Joined: Aug 11, 2011
Posts: 392
Location: Raleigh NC
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| Posted: Mon Nov 14, 2011 11:17 am Post subject:
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| Quote: | | Wouldnt a longer trigger mess up envelopes and stuff? I kind of thought it was a trigger on event. |
That would really depend on what the trigger does in the circuit. If it's feeding edge-triggered devices, it won't make any difference. If it's feeding a level sensitive device, it would definitely be possible to screw things up by extending the trigger too long.
One way people deal with this issue is to run the signal through a little R/C differentiation circuit which converts the incoming trigger into an spike of a known length. That way they can be sure of getting an edge.
Take a look at the MFOS Dual A/R generator for an example of this.
Best Wishes
Gary |
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jumunius
Joined: Apr 19, 2010
Posts: 330
Location: San Francisco, CA
Audio files: 13
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| Posted: Tue Nov 15, 2011 1:06 am Post subject:
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| Mongo1 wrote: | | Quote: | | Wouldnt a longer trigger mess up envelopes and stuff? I kind of thought it was a trigger on event. |
That would really depend on what the trigger does in the circuit. If it's feeding edge-triggered devices, it won't make any difference. If it's feeding a level sensitive device, it would definitely be possible to screw things up by extending the trigger too long.
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In my experience running gate signals through some of TH's various drum circuits (MPS, etc) the gate length delays the decay from happening. So if you run gate cv from a keyboard controller and vary your note length, you get delayed release from your drum circuit to the point that it no longer sounds percussive if you're holding the notes down. So it would follow that a 1ms and 10ms trigger would actually produce very slightly different results, although in this case both would probably sound fairly percussive.
_________________
-Jim |
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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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| Posted: Tue Nov 22, 2011 5:00 am Post subject:
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More as i find them;
One of the circuits (the trigger repeater thing i think; never have internet and book together at the same time!) requires a trigger of 15v. How would i make one of those then, the trigger conditioner puts out 12v.
Cheers |
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Paradigm X
Joined: Feb 15, 2011
Posts: 252
Location: Null and void
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| Posted: Tue Nov 29, 2011 3:56 am Post subject:
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Hmm, ok, maybe an opamp to boost it?
Also, what exactly is VC noise source, what does the cv control, volume? |
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Mongo1
Joined: Aug 11, 2011
Posts: 392
Location: Raleigh NC
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| Posted: Tue Nov 29, 2011 1:49 pm Post subject:
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I don't have the book, so I can't really comment.
Regarding VC Noise, it probably means that you have a digital noise generator ( a shift register with feedback), and you're using the VC to control the frequency of the oscillator driving the shift register.
The only other thing I can think of would be if you had a LP Filter following your noise source, and use the VC to sweep the filter.
In either case you'd be able to control the noise spectrum with a VC, which is pretty useful.
Gary |
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