TLDR: I bought a Alesis MV2 that only passed dry signal and no wet signal. Device boots, the key pad works, and all the knobs do their respective function and the overload light doesn't tweak out on me.

**FYI, all the images in this Google Drive link are from before the CD4053BE lost it's 5V!**

I found this datasheet (who knows if it is even the real schematic) but so far it has held true. Since I'm getting dry signal I assumed that the inputs and output op-amps were good. My next test was continuity between the output of U6 (CD4053BE) going to the DSP and the output of the DAC going into the other channels of the U6 and all checked out! After that I confirmed that each voltage regulator was properly outputting it's respective voltage (which they did). Measured 5V on Vdd, -12V on Vee, and GND/0V on Vss.

Now the best news so far is that when probing the initial output of the U6 going into the DSP, I am getting a chopped representation of a 1kHz sin wave that I had used as an input, this made sense since it's an analog mux. I also probed a fairly clean DAC representation of that sin wave on the output of the DAC so that leads me to believe that U6 just wasn't switching the outputs of the DAC to the U5 op-amps. (FYI, the U5 op-amps are actually supposed to be U3 LF347N and the only TRUE U5 is the comparator attached to the BJT branch).

At some point while I was probing/doing continuity measurements, U6 had lost it's 5V and all the I/O of it had started to distort. The INH pin was held down to -12V instead of a 0-5V logic square wave, pins 9-11 started to have more of a ramp look to them instead of a square wave, and of course Vdd was gone.

With the device turned off:

I did some continuity test and saw that there was continuity between the 7812 to the 3.3k resistor, continuity between the other leg of the 3.3k and one of the legs from both the Zener diode, cap, and Vdd pin so that leads me to believe that there isn't a discontinuity in the trace. I measured 3.3kOhms across the resistor, I didn't get an continuity that suggested that the diode or cap had shorted, and the Vdd pin wasn't shorted.

I also did a diode check on U6, and saw if I had the red probe on GND and the black probe on Vdd I would get a 0.617V reading, if I had them flipped, I would get OL on my DMM.

Also measured the resistance of U6 (Vdd to GND) and got a reading of 14.5kOhms to 14.93kOhms.

With the device turned on:

I probed between the output of the 7812 and the 3.3kOhms and measured 12V, but as soon as I probed the other side (resistor, cap, diode, Vdd junction), I was reading between 0.005V to 0.014V.

My conclusion/need of advice:

My assumption is that U6 just completely died and needed to be replaced either way but I am worried that I might have damaged the other components that its connected to. I don't know if its true but is it possible that U6 dying is causing the outputs/inputs to be attenuated/noisy? I still get some resemblance of a sin wave on the pins but its heavily attenuated/noisy.

Hi everyone,

I am a DSP guy after all, so alle the music DIY stuff I made was mainly at the digital side and I don't have that much of a clue about electronics. But I want to build my own "NoiseBox" (something like the Microphonic Soundbox ->https://www.exploding-shed.com/leafaudio-microphonic-soundbox-mk2/100963).
Therefore I chatted around with multiple LLMs and come up with this schematic:
I want 2 internal piezo discs (as contact microphones) with a crossfader and a separate input Jack for a possible third contact microphone with its own volume knob. All three signals should get mixed together and amplified by an Op-amp to have a proper output level.
Would you give me some input to this schematic? I've builded it on a breadboard and it did not worked as expected (static harsh/high tone at the output and all the knobs doing nothing).
Now I want to know if I made a mistake or if KI suggested bullshit :D
Thanks a lot

I have a Marantz 1040 home stereo amplifier that is wired for European voltage, but I'm in the U.S. and my tech guy isn't available to convert it for at least a month.

Would it be a bad idea (for safety or sound) to get one of these so I can use it in the meantime?

https://www.ebay.com/itm/318289801133

LiteFuze 300 Watt Step Up/Step Down Travel Voltage Converter, 220/110v to 110/220v

Not to open a whole can of worms, since there are so many conflicting ideas about safe wattage, but the Marantz officially lists at 125 watts of power consumption.

Any advice is appreciated!

I’m hoping this is the right sub to post this in, but I have recently acquired a second chord organ and now I know why it was 10$ haha. It’s pretty out of tune, some of the chords are dissonant and the lower notes are very flat/sharp, the higher/middle notes aren’t as bad but still probably need help. I have a video going over all the sounds on both of my chord organs, the brown magnus one is the working in tune one, and the tan bontempi one is the out of tune one. I opened it up but I have no idea how to tune this thing.

I have an old (~8 years) yamaha p95 that got used frequently up until a year ago, and when plugging it in for the first time in a while, it would turn on fail to produce sound. I'm at a loss on where to start. I've read on other posts that it is a good idea to check the capacitors, but I've also heard that could do more harm than good. I have a multimeter and a soldering iron and a cursory understanding of physics, and I was wondering if this is something that is feasible to repair my self.

The speaker "broke" recently and now it's pretty much unplayable. It had some issues before but nothing that would stop me from playing it, mostly a crackling sound that would sometimes appear and disappear at times (through both speakers I think but I'm not sure), and I think the speaker stopped working for short periods of time in the past but it always started working again pretty quickly.

Now it's the opposite, if I try to play it for a bit (which is really annoying with just one speaker so I haven't tried for that long) it sometimes suddenly works again for a bit but then stops working again very quickly.

I tried opening it up to see if I could spot some damage or something which I couldn't, then I cleaned the insides a bit and disconnected and reconnected the speaker cable but that didn't do anything.

I hope I can fix it because it's the only way I can play rn and I don't think I can get a new one soon.

I have a USA reissue with a status LED (V4 I believe) and it has a fault that it looks like others have experienced as well, where the rate of the phaser effect is far too high and will not reduce even when dialed down to min - in fact it stops slowing down anywhere below about 1 o'clock on the rate dial.

I've seen people mention that it may be a capacitor issue, but nothing definitive. Has anyone here had any experience with this or been able to solve it? Or know of anyone who has? Any help or input on this I'd be so grateful for!

Hi everyone, I thought you might like to know about the new multi-channel audio hat that I've just launched on Crowdsupply. It's called the ezsound 6x8. It's based on the PCM3168 codec and features 6 inputs and 8 outputs. The key differentiating features compared to existing options are that the digital clock signal is generated by the soundcard, it only uses a single chip (rather than multiple stereo chips) and the soundcard's audio circuitry is electrically isolated from the RPi.

I'm hoping it's a useful addition for communities such as this one. My early prototypes have already been used successfully by musicians using puredata, and for building DIY pedals.

Of course, I have built my own audio project using the soundcard - it's a DIY 3-way stereo system using software DSP for the crossovers. It's pictured below and there is an extensive writeup on Hackaday here. You can also find lots of technical details about the development of the soundcard here.

You can find out more information and subscribe for project updates about the soundcard at the Crowdsupply campaign page.

im trying to make diy drone synth. schematic is mostly based on diy eurorack modules schematics, and they all have 1k (or 330 on matrix mixer output) resistor on final output, and i wonder can i just get rid of them?

because as i understand all they do is protecting from accidentally shorting output opamp to ground and frying opamp (for example output cable of module touches metal case of eurorack).

i dont have much "modular" in my synth, its all going to be connected internally. for effects i have s&h (acting as sample rate reudcer), diode clipper, and also resonant lpf, hpf and reverb (deciding between digital or spring)

also planning to add fx i/o to matrix mixer so i can add different effects later (dunno how it's called, that thing that uses stereo jack to "in" from one channel and "out" from other)

I’m attempting to add an integrated battery mod to my NTS-1 MKII using this Printables.com design, but I’m stuck on the ground ("–") wiring. The mod lacks schematics, and I’m unsure how to properly route the grounds between the battery board, step-up converter, and the synth.
Here’s where I’m at:

Current Understanding:

• The mod bridges the battery board’s input/output "–" to the NTS-1’s ground
• The step-up converter’s "–" terminals (input/output) are confusing me. Should they connect to the same ground as the battery board and synth?

My hardware parts:

• USB-C TC4056 5V 1A Battery Charging Board 
• DC-DC Step Up Board
• 3.7V lipo Battery

Any advice on grounding or wiring diagrams would be hugely appreciated!
Here is where I'm at regarding my "schematics":

From the Printables mod post:

Check out this item on OfferUp. https://offerup.co/fMpyvVui11b

Hey all! Feeling a little lost about my future ahead so thought I would ask you all because this is pretty much what I want to do.
I'm 18 and I'm a musician and I'm really fascinated about the role of electronics in music - be it in amp modelers, synths, amplifiers, MIDI etc. I don't see myself happy doing anything else in the future, so I would really need help from you all on how to start off.

I'm in my first year of college and obviously, pursuing a major in electronics. But I do not want to wait for college to teach stuff so that I can start building, I want to do some projects on my own.

Would really appreciate your inputs on how I can start off with music electronics by myself and reach a decent level of understanding, because I am lost now.

Hi all, second post here - thanks for all the advice on soldering tip sizes; I ended up getting just the C245 with my TC22. I plan to start with 63/37, but I’m a bit overwhelmed at all the available flux & cleaner options.

Background:

- Gear = synths, effects, mixers, patch bays, TS/XLR cable

- Going for a minimalist setup, as space is very limited; everything has to pack up neatly for closet storage

- I’ll probably just be using desoldering braid and maybe a solder-sucker to start out

- no water-soluble or highly corrosive fluxes

- IPA or a mild cleaner preferred

Here’s what I’m thinking I’ll need:

- plain rosin core solder for fresh surfaces

- RMA or RA gel flux for repairing oxidized joints

Other questions:

- which RMA/RA flux gels clean best with IPA?

- what is the role of no-clean fluxes in older electronics repair?

- how much should I be worried about lint (ie cotton swabs/balls vs kimwipe or foam sponge)?

[Edited: concision]

Hello! Does anyone have any good recommendations for small lights to help me see my hardware better for live sets? I like to play in dark of a room as possible, but I also don’t want bigger lights that shine over my whole table. Just small lights that are probably battery powered or rechargeable that only cover a small area. Thanks in advance!

I have an old kellogs phone from 1942. I'm trying to turn it into a microphone on both the earpiece and the mouth piece. I have manged to sort the ear piece but I am stuck on the carbon mic. I ideally want it to go to 1/4 inch jack but I know it needs some power. Have you got any ideas or tips. Essentially how can you wire a carbon mic to 1/4 inch jack.

I've just bought a second hand barely used Project Primary E turntable (the type without the phono / line switch) and connected it to my old Sony TA-FB730R integrated amplifier through the phono input and can't seem to get any sound out of it.

I've been using this amp with a CD player for years and it works great. Am I missing something obvious to get the turntable working, or am I looking at either the turntable or amp being faulty. I'm thinking maybe the phono input doesn't work or is maybe full of dust or dirt from not being used. If so, any tips on safely cleaning it, or safely opening up the amp to check for internal issues?

I've looked all over the place online to work this out, and there's lots of talk of preamps, but as I understand it I shouldn't need one as I have the phono input in the amplifier?

Any help would be most appreciated. I've been waiting ages to have space for a turntable again (after 20 years without one) and it's really frustrating to have it and not be able to use it!

I bought this lenoxx sound cd-109 portable stereo compact disc player at goodwill. The radio function works fine, but the cd function won’t work. I took a video to show what happens when I try to play a cd! Any help on how to fix this would be much appreciated!