Search found 1355 matches

by Don T
Wed Apr 28, 2021 5:11 pm
Forum: Music Tech DIY
Topic: SSI2131 Thread :)
Replies: 13
Views: 303

Re: SSI2131 Thread :)

I think an LFO should have an ignition key and large START button. "Oh... you want me to start now, eh?...." Neil :hihi: Indeed! Maybe I should get key switches, and some of those flip-cover aircraft switches. AND them together, so it requires both to start. :mrgreen: I vote for a large, Dr. Franke...
by Don T
Wed Apr 28, 2021 1:01 pm
Forum: Music Tech DIY
Topic: Why no one made a VCA module with 6AS6/5963 tubes
Replies: 13
Views: 395

Re: Why no one made a VCA module with 6AS6/5963 tubes

Perhaps an analogy which paints this is two flashlights that have bulbs which illuminate a room to the same degree, except that the bulbs are of different designs, one uses a AA battery which is 1.5v and the other uses a square 9v battery which is 9v. One might be smaller than the other, there may ...
by Don T
Tue Apr 27, 2021 7:37 pm
Forum: Music Tech DIY
Topic: Why no one made a VCA module with 6AS6/5963 tubes
Replies: 13
Views: 395

Re: Why no one made a VCA module with 6AS6/5963 tubes

Look into these: 12AC6 12AF6 12BL6 12CN5 12CX6 12CY6 All remote-cutoff pentodes, all work with 12V on the plate, but most can accept up to 24V on the plate. I have a stash of 12U7 and 6GM8 that I am planning on experimenting with in some synth circuits. The 12U7 is a 12AU7 designed for 12V plates, a...
by Don T
Tue Apr 27, 2021 7:29 pm
Forum: Music Tech DIY
Topic: Transistor Based Low Pass Gate schematic?
Replies: 55
Views: 2307

Re: Transistor Based Low Pass Gate schematic?

I was working on the problem, and I came up with what could be a simple and elegant solution. Then Xvive started making vactrols again. I put the project aside. Perhaps I should take it up again, but I need to buy a few parts that I don't have. Is there still a delivery delay from Mouser?
by Don T
Tue Apr 13, 2021 7:37 pm
Forum: Buchla, EMS & Serge
Topic: OG Buchla Easel vs Command: Extra banana patch points
Replies: 8
Views: 472

Re: OG Buchla Easel vs Command: Extra banana patch points

B2080-01A.jpg It looks to me if you want to randomize or otherwise change the step order on the BEMI, BUSA, and clone 208s, you'd have to come up with a completely digital solution for Card 1. Card 1 is an analog sequencer built using CMOS chips, it's not exactly digital in function. Perhaps a card...
by Don T
Tue Apr 13, 2021 3:30 pm
Forum: Music Tech DIY
Topic: Recommend a method to measure Va (early voltage) of PNPs?
Replies: 60
Views: 758

Re: Recommend a method to measure Va (early voltage) of PNPs?

I know a curve tracer is expensive, but would that be the more reliable way to do this?

[EDIT]: Just trying to wrap my head around the problem/point of interest
by Don T
Sat Apr 10, 2021 5:14 pm
Forum: Music Tech DIY
Topic: Build a buchla 208 rev2
Replies: 1073
Views: 92030

Re: Build a buchla 208 rev2

I have a question about my Buchla 208r rev2 that I'm hoping someone can help me out with. I have my tracking set to 1.2v and tracking is good, but when I go up in octaves to around C6, sometimes C5, CO sounds like it is breaking up or modulated by something. This doesn't happen every time which is ...
by Don T
Fri Apr 09, 2021 8:29 pm
Forum: Buchla, EMS & Serge
Topic: Noisebug press release / Buchla future
Replies: 392
Views: 17559

Re: Noisebug "just say no" press release

I would like to point out one thing - Inside almost every student-to-midlevel violin is a label that resembles the below: https://www.the-romantic-school-of-music.com/How_To_Choose_A_Violin/Stradivarius_NOT_.jpg The words "copy of" usually appear in very small type at the top of the label, with a fa...
by Don T
Wed Apr 07, 2021 8:41 pm
Forum: Buchla, EMS & Serge
Topic: The M.E.M.S Project module photos and info
Replies: 33
Views: 1698

Re: The M.E.M.S Project module photos and info

davebr, there have been many times that I have been jealous of your skill, and the things that you have worked on, but this takes it to newer and much higher levels! Congrats!
by Don T
Sun Apr 04, 2021 1:50 pm
Forum: Music Tech DIY
Topic: suggested circuits/pcbs to sum positive CV
Replies: 6
Views: 170

Re: suggested circuits/pcbs to sum positive CV

Almost any basic DC-coupled mixer circuit would work
by Don T
Sat Mar 27, 2021 9:10 pm
Forum: Music Tech DIY
Topic: Korg Poly 61 Problem (Popping/Crackling sounds)
Replies: 3
Views: 121

Re: Korg Poly 61 Problem (Popping/Crackling sounds)

Oh ok didn't thought they can take a damage.. I have clearly corrosion on some leads, I will replace the parts and hopefully it works again then:) Yes, it's pretty insidious. The corrosion can actually creep inside the shell of a chip and damage internal connections. Resistors and caps are especial...
by Don T
Fri Mar 26, 2021 7:11 pm
Forum: Music Tech DIY
Topic: Korg Poly 61 Problem (Popping/Crackling sounds)
Replies: 3
Views: 121

Re: Korg Poly 61 Problem (Popping/Crackling sounds)

If any traces near the battery look discolored, you may need to install jumpers for that trace/connection. If any of the corrosion shows on the lead of a component, replace that component, even if it's a chip.
by Don T
Thu Mar 11, 2021 8:05 pm
Forum: Music Tech DIY
Topic: Buchla 259 Vintage PCB2 grid map
Replies: 6
Views: 197

Re: Buchla 259 Vintage PCB2 grid map

Building a 259 vintage PCB2 is so tedious as you spend all your time searching for the part locations. I finally decided to grid the PCB and make a listing of all the parts. I should have done this years ago as it makes the build go so much faster. I didn't verify it on the entire build so there ma...
by Don T
Fri Mar 05, 2021 3:42 pm
Forum: Music Tech DIY
Topic: Extra eyes on a simple noise/filter circuit?
Replies: 1
Views: 114

Re: Extra eyes on a simple noise/filter circuit?

I look at it this way, the buffering couldn't hurt, may actually help, and if you're going to use a TL084 you have two spare opamps anyway... Seriously, it would depend upon the output impedance of the noise/filter circuit compared to the input impedance of the next stage. That said, a buffer makes ...
by Don T
Wed Mar 03, 2021 7:36 pm
Forum: Music Tech DIY
Topic: Replacing analog pots with digital pots
Replies: 15
Views: 544

Re: Replacing analog pots with digital pots

Why not this: Set up a midi/CV converter for each parameter you want to control, then inside the synth, lift the wiper terminal from the board (or just disconnect the wire if hardwired), then use a passive mixer to combine the two signals, then connect that mixed signal to where the pot's wiper was ...
by Don T
Tue Feb 23, 2021 11:08 pm
Forum: Music Tech DIY
Topic: A quadrature triangle VCO
Replies: 228
Views: 4181

Re: A quadrature triangle VCO

The real Cadillac solution, which is obviously not probably realistic or pratical, would be to have the effective integrating cap size decrease as the FM index knob is decreased. This would keep the frequency selected by the tuning knobs constant while changing the depth of the FM modulation, and k...
by Don T
Tue Feb 23, 2021 11:00 pm
Forum: Music Tech DIY
Topic: What's the best way to learn how to troubleshoot circuits?
Replies: 25
Views: 804

Re: What's the best way to learn how to troubleshoot circuits?

A book that has been infinitely helpful to me: https://www.amazon.com/Linear-Electronics-John-Linsley-Hood/dp/1882580494/ It explains pretty much how everything works, in a much detail as you want. Another thing that really helps me is building the circuit in this simulator: https://www.falstad.com/...
by Don T
Mon Feb 22, 2021 10:25 pm
Forum: Music Tech DIY
Topic: Buchalish 111 Ring Mod PCBs
Replies: 192
Views: 21294

Re: Re:

and I'm always expanding the documentation section of the historic buchla (100/200 series) pages , with more schematics and notes. Please let me know if you have other information to share! happy wiggling! Grant Richter has uploaded loads of schematics in the Buchla FB group With Grant's permission...
by Don T
Thu Feb 18, 2021 5:18 pm
Forum: Music Tech DIY
Topic: Recapping Korg Mono/Poly question
Replies: 8
Views: 263

Re: Recapping Korg Mono/Poly question

Thanks for the input! My reasoning is that the synth has not been played for the last ~35 years. I assume that some of the capacitors are dried-out. I keep reading about the tantalum caps and I see four of them on the m/p. Can I just replace for regular electrolytic caps? 1. If you know someone wit...
by Don T
Tue Feb 09, 2021 12:12 am
Forum: Music Tech DIY
Topic: [IC] vintage 6-voice polysynth kit project?
Replies: 90
Views: 4483

Re: [IC] vintage 6-voice polysynth kit project?

Cablebasher wrote:
Mon Feb 08, 2021 3:53 pm
We’re going to need a bigger roll of solder.
Get two...
Trust me
by Don T
Tue Feb 09, 2021 12:09 am
Forum: Music Tech DIY
Topic: Minimoog Model D replica build thread
Replies: 34
Views: 1383

Re: Minimoog Model D replica build thread

The quality of an AB pot (carbon part ,sealed against dust,mechanical shaft )compare to an alpha pot is night and day . After 50 years, most of them work like new . Except for the ones in your photos which have already been replaced with CTS pots. <--Those CTS are not original. Don't get me wrong, ...
by Don T
Thu Feb 04, 2021 8:36 pm
Forum: Music Tech DIY
Topic: Roland j3xp Voice issue
Replies: 18
Views: 171

Re: Roland j3xp Voice issue

Glad it worked out!
by Don T
Thu Feb 04, 2021 8:35 pm
Forum: Music Tech DIY
Topic: juno 6 problem, juno 6 doing weird things
Replies: 38
Views: 766

Re: juno 6 problem, juno 6 doing weird things

thanks for all the replies! i saw that the 3 big black capacitors loosing some of their liquid, if im not misunderstanding. i attached a picture, could that be the problem? i will check the pcb tomorrow in detail for bad solder joints. What you are seeing there is the glue used to hold the cap in p...
by Don T
Thu Feb 04, 2021 4:42 pm
Forum: Music Tech DIY
Topic: Combined Through-Hole / SMT footprint (vertical TH and 0603 SMT)
Replies: 26
Views: 550

Re: Combined Through-Hole / SMT footprint (vertical TH and 0603 SMT)

Use 1206 footprints and add holes in the middle of the pad (Kicad doesn't like that, it will give you "courtyards overlap" errors), or create vertical THT resistor footprint that the holes are centered where 1206 pads would be, then make the pads square (Kicad likes this better) Don't ask me how I k...

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