Search found 218 matches

by 555x555
Thu Jan 09, 2020 12:33 am
Forum: Music Tech DIY
Topic: Are there any analog phase modulation VCOs?
Replies: 141
Views: 9664

Re: Are there any analog phase modulation VCOs?

Seems to me like the problem implementing this in analog is less getting it to work at all than getting the extreme modulation indices that are easily achievable in digital. IIRC, at full blast the DX7 shifts the phase something like 23 cycles... that's a lot of wavefolding. One of the great thing a...
by 555x555
Fri Dec 13, 2019 11:43 pm
Forum: Music Tech DIY
Topic: More channels in an adc/dac
Replies: 7
Views: 621

Thanks all! Graham - yes, digital audio. For CVs I know you can just use a mux or i2c or something like that. emmaker - my understanding was that TDM is still something that is single chip to single chip. Is this not so? Maybe I should read up a little more... guest - hmmm, so basically some version...
by 555x555
Fri Dec 13, 2019 1:27 pm
Forum: Music Tech DIY
Topic: More channels in an adc/dac
Replies: 7
Views: 621

More channels in an adc/dac

My understanding of all this digital brouhaha is a work in progress so please bear with me. I'm wondering how the interface with multichannel DACs is done. My understanding is that generally you have an I2S connection that has basically clock + samples from the processor to the DAC/ADC. I think I kn...
by 555x555
Fri Nov 29, 2019 12:38 am
Forum: Music Tech DIY
Topic: 3Peak Opamps
Replies: 25
Views: 863

Yeah, the new design is part of what’s interesting about them. CMOS, 36V, low distortion, decent precision. Idk much about semi fabs, but offhand this seems like a pretty innovative chip.
by 555x555
Wed Nov 27, 2019 10:30 pm
Forum: Music Tech DIY
Topic: 3Peak Opamps
Replies: 25
Views: 863

Thanks for all the opinions. And yeah, TL0s are great and cheap for the JLC PCBA service, so I’m still mostly using them. But sometimes a design can benefit from better specs. Re: China, I think it’s maybe time to stop treating it as a monolith. lcsc has a good reputation, and seems to me they’re an...
by 555x555
Mon Nov 25, 2019 2:19 pm
Forum: Music Tech DIY
Topic: 3Peak Opamps
Replies: 25
Views: 863

3Peak Opamps

Scrolling through lcsc.com, stumbled on to these opamps which seem to have pretty excellent specs, especially for the money: https://datasheet.lcsc.com/szlcsc/3PEAK-TP2604-SR_C126446.pdf Noise isn't great, but not much worse than the TL0s. Everything else seems to be much better for most application...
by 555x555
Wed Nov 13, 2019 11:33 am
Forum: Music Tech DIY
Topic: Does it exist: M7 x 0.75 round nuts in 10mm od?
Replies: 5
Views: 364

IIRC, ettinger has a 200€ minimum order. Maybe a group buy could be a thing? Or better, maybe we could convince synthcube/thonk/etc to stock them?
by 555x555
Sat Oct 26, 2019 10:09 am
Forum: Music Tech DIY
Topic: Desoldering braid that doesn’t suck
Replies: 24
Views: 737

Thanks for all the replies! I went with MG Chem bc of all the enthusiasm. But I’m sure others finding this thread would appreciate additional replies if you want.

Re: solder pump: easier for desoldering simple things. But for headers or jacks I’ve found you just need braid.
by 555x555
Thu Oct 24, 2019 12:49 pm
Forum: Music Tech DIY
Topic: Desoldering braid that doesn’t suck
Replies: 24
Views: 737

Yeah, added flux is the only way I can get it to work at all. My flux pen also sucks, though, and tends to either deliver none or all of the flux. Problems...
by 555x555
Thu Oct 24, 2019 11:17 am
Forum: Music Tech DIY
Topic: Desoldering braid that doesn’t suck
Replies: 24
Views: 737

(Or rather, that *does* successfully suck solder).
by 555x555
Thu Oct 24, 2019 11:16 am
Forum: Music Tech DIY
Topic: Desoldering braid that doesn’t suck
Replies: 24
Views: 737

Desoldering braid that doesn’t suck

Recommendations?
by 555x555
Sun Sep 29, 2019 11:04 pm
Forum: Music Tech DIY
Topic: Better amplitude limiting in state variable oscillators
Replies: 3
Views: 262

Yep. That's pretty much the circuit. (Fig 5.1.2 here: https://sound-au.com/articles/sinewave.htm). The only difference is mine has a resistor to ground along with the diodes to control the distortion and feedback level a bit more independently. Although I guess that since the other resistor goes to ...
by 555x555
Sun Sep 29, 2019 8:56 pm
Forum: Music Tech DIY
Topic: Better amplitude limiting in state variable oscillators
Replies: 3
Views: 262

Better amplitude limiting in state variable oscillators

I'm not sure if someone else has come up with this before, but here's an alternative to using Zeners for limiting the amplitude of oscillation that's slightly cheaper and IMO better. I haven't analyzed this in the case of this topology being used to filter, so that would be interesting if someone wa...
by 555x555
Fri Sep 27, 2019 11:58 am
Forum: Music Tech DIY
Topic: 808 hihat clone PCB set
Replies: 64
Views: 7498

So you're generating sound. Try running an LFO to trigger and probing that way. My guess is one of those transistors is the culprit - either because it got fried when some leads got bridged or because it's in there backwards.
by 555x555
Sun Sep 22, 2019 11:37 pm
Forum: Music Tech DIY
Topic: 808 hihat clone PCB set
Replies: 64
Views: 7498

Also, I just remembered: my post at the end of this thread associates the components with the original 808 schematic. It might help you troubleshoot/trace.

viewtopic.php?t=123835&start=75
by 555x555
Fri Sep 20, 2019 10:10 am
Forum: Music Tech DIY
Topic: 808 hihat clone PCB set
Replies: 64
Views: 7498

Almost definitely unrelated, but it looks like you need to wash the flux off those boards :hihi: “No sound” could mean just about anything. The main board has 99% the original 808 circuit. If you look up the schematic for the Eric archer remake of the 808 (above), you should be able to follow the tr...
by 555x555
Tue Sep 17, 2019 6:46 pm
Forum: Music Tech DIY
Topic: Quantum Rainbow II Help!
Replies: 2
Views: 328

Well I'm not sure what it is, but the markings are M4-59-t and the text is oriented such that it goes from top to bottom. Same chip as the one above the header. Given that, I'd guess something to do with reverse polarity protection.
by 555x555
Sat Sep 14, 2019 9:20 pm
Forum: Music Tech DIY
Topic: Best practice regarding buffering & impedance, ground?
Replies: 22
Views: 991

Thanks for the detailed responses! Noise from where exactly? Sorry if that feels pedantic. Not at all :-). The noise comes from the resistance itself. It's known as "Johnson Noise." I'm not sure I understand it 100% myself, but I know it's there, and if compounded with many connections, or with an ...
by 555x555
Fri Sep 13, 2019 11:52 pm
Forum: Music Tech DIY
Topic: Best practice regarding buffering & impedance, ground?
Replies: 22
Views: 991

100k (input)/1k (output) is the "standard" for Eurorack, but it is better to understand the tradeoffs and make intelligent decisions than to use that. That being said, if you don't understand the tradeoffs, putting 100k/1k everywhere will almost definitely work and not cause any major problems. With...
by 555x555
Thu Sep 12, 2019 12:15 pm
Forum: Music Tech DIY
Topic: Godda@mn spring reverb tanks
Replies: 34
Views: 1806

Like someone already said, driving from a v-to-current is said to be the best. But why not recover with a current-to-voltage converter/amp? Aren’t there the same impedance-frequency relationships on the recovery side? I have the same questions about guitar amps...everyone seems on an endless quest f...
by 555x555
Sat Aug 24, 2019 12:29 pm
Forum: Music Tech DIY
Topic: How should I label quadrature outputs?
Replies: 17
Views: 575

I think I'm gonna go with Out ℜ/Out ℑ. There are some very strong arguments of canonicity for Out/Out+90, but I thought of another problem with it. My outputs are in a true 90 degree phase relationship, and I think Out+90, for a complex wave, to most people actually conveys a 90 degree delay rather ...
by 555x555
Wed Aug 21, 2019 12:12 pm
Forum: Music Tech DIY
Topic: How should I label quadrature outputs?
Replies: 17
Views: 575

How should I label quadrature outputs?

I'm designing an oscillator which will have two outputs in quadrature with each other, but not a sine / cosine. How should I label that? Seems like no option is perfect. Options: Out/Out+90° - Clear. But asymmetrical. Out is not more canonical than Out + 90°. Sin/Cos - Clear. Symmetrical. But it see...
by 555x555
Wed Aug 14, 2019 9:11 pm
Forum: Music Tech DIY
Topic: Panel and PCB Manufactures
Replies: 24
Views: 1676

The PCB front panels are made pretty much exactly like a PCB. I’ve used Kicad to design a few; I’m sure Eagle would work fine, too. What I want to know, though, is where people are ordering them for good resolution and consistent registration. Or maybe people are just limiting the design to things t...
by 555x555
Mon Aug 12, 2019 9:33 am
Forum: Music Tech DIY
Topic: external power supply case connectors?
Replies: 13
Views: 635

I’ve used these: https://www.mouser.com/ProductDetail/523-T3302550 https://www.mouser.com/ProductDetail/523-T3301551 Note you have to buy the pins separately. They have a relatively low contact resistance and good crimp connectors. They say 18awg, but I’ve crimped 14. Four pins, two for ground. You...
by 555x555
Mon Aug 12, 2019 9:18 am
Forum: Music Tech DIY
Topic: external power supply case connectors?
Replies: 13
Views: 635

I’ve used these: https://www.mouser.com/ProductDetail/523-T3302550 https://www.mouser.com/ProductDetail/523-T3301551 Note you have to buy the pins separately. They have a relatively low contact resistance and good crimp connectors. They say 18awg, but I’ve crimped 14. Four pins, two for ground. You ...

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