DIY Project Recommendations

I often find it difficult to solder to contacts with shiny chrome plating, but it’s much easier when it’s abraded or removed. Try a little sandpaper or a abrasive tool with a Dremel type rotary tool and the solder might take.

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That’s a good shout!

I still worry about demagnetizing the poles though.

The screws themselves should not be magnetic, there should be two bar magnets in the pickup that provide the magnetic field.
Buy longer screws?

If the screws are the only source of magnetism then you could easily clip a bar magnet or neodymium to the back depending of the desired tone.

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That’s true actually. There’s two bar magnets running along side them, so I guess the poles are “just screws”.

Longer screws are a great idea! I’ll test some tomorrow (hopefully they are metric and not some odd/imperial things)

The magnet option is kind of interesting too. I guess it’s a matter of testing, but I could conceivably just use some ferrous bits of metal (nuts or something) to magnetically hold onto the poles. Not super sturdy, but it may be an option too.

Rereading your intentions, it occurs to me that it might be better to separate the switching matrix from the pickup entirely. Most of the time, if the pole pieces are high enough to be able to be hit by the strings they are too high anyway. Using the same principle, you could mount an insulated block just before or after the pickup with adjustable contacts (machine screws) and have them threaded into nuts set into the insulated base, solder your contacts to the nut instead of the screws?

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I could have been clearer, but I think part of what I’m after is that “floppy string clunking against a pickup pole” sound. That kind of thunk/thud you get when the strings are really loose.

My intention is having something no more than 8-10" or so with regular(ish) gauge strings so they are super droopy.

I don’t know if it will work exactly like I’m thinking, but what I’m imagining is using those thunk sounds in conjunction with the switching that is tightly synced (heading to a modular) to create a (hopefully) interesting percussion-ish instrument.

On a super positive note, the screws/threads appear to be M3 and I have some decently-lengthed bolts on hand. I’m sure that will change the tone in some way, but given my idea, I don’t think it will matter too much.

Knowing I have the bolts for this, I can hopefully whip up an initial test/prototype and see if it all works how I think.

edit:
Can’t do consecutive replies now?

The good news is the bolts slide in nicely, and are plenty long so I can wrap the cables around the screws and lock the in place with two thin bolts.

BUT

My bolts are non-ferrous (stainless steel perhaps?) meaning they would be useless as pickup poles…

I guess I want carbon steel for this to work right?

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I am guessing you are in a test it see situation here. You could try taking a small magnet to the hardware shop and seeing if any of their m3 machine screws offer any pull through the packaging. Some good news is that cheap hardware advertised as stainless has so little chromium in it -or just a thin coating -that they will still behave magnetically.

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Yeah that’s a good shout. I ended up ordering some stuff online since the local hardware places don’t have an amazing selection of hardware, but if that fails, I’ll take a trip with a magnet and see what I get.

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On an unrelated note.

Does anyone know much about getting audio from the mics on those shitty Apple EarPods?

Inspired by this:

…I ordered a couple knockoff earpods (I’ve long since rid myself or lost all of mine) with the intention of making cymbal sizzle things, that also double as microphones.

I found this page which explains how the TRRS is wired up:
https://www.circuitbasics.com/how-to-hack-a-headphone-jack/

Specifically this diagram:
TRRS-Wiring-Diagram

But in connecting those pins directly to the input of an amp (via alligator clips) I don’t seem to get any audio at all.

I always presumed that these mics were “powered”, but in looking at the wiring I’m not sure how that could be happening with only 4 pins.

It’s also possible that the signal is incredibly quiet and I need to crank the input a ton to even hear it.

Has anyone used earpod-style headphones as “regular” mics before?

i’ve done field recording using standard earbuds (without mic) plugged straight into the mic input of a MiniDisc™ walkman®. It worked, with the expected “quality” and weak sensitivity of such repurposed diaphragms.

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That’s a good point.

I’ve used headphones in a similar way before, though it’s a definitely a specific kind of sound. I’m hoping for that overblown/distorted input (ala that vid above) so would be good to figure out how to tap into the mic audio.

Yes, they are powered by the unit they are plugged into, I think that most apple stuff supplies around 2-3v via the mic pin. There’s usually a DC blocking cap as part of the power circuitry and the audio is taken off of that. If you do a search on electret mic power you’ll see what I mean.

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Gotcha, that makes sense.

Yeah, loads of shit comes up for searching that. I was searching for “headphone mic wiring”-type stuff and that led nowhere.

Will also order a bunch of tiny elecrets to do some testing with too.

I could use some help DIYing a passive modular-to-line level box. Basically, this: Ladik P-520 4ch(out) line - Eurorack Module on ModularGrid

Despite building stuff for many years now, my theory knowledge is garbage. Playing around with a t-pad calculator (recommended by someone on the MW forum), I’m inputing an input impedance target of 1k (from modular) and an output impedance target of 10K (line level on my Soundcraft mixer).

Does that sound right? For a -20db pad, I’m getting roughly 400R for my input resistor, 1k for my output resistor and 700R for the bridge.

EDIT: Or can I make this simpler with just an L-pad and something like 10k on input and 1k on output? That doesn’t get me impedance matching though, right?

Impedance matching is pretty much a thing of the past unless you want to connect vintage tubes and transformers type gear. To simplify (a lot), modern gear transfers voltage, which you’ll just want to attenuate, not power in which case impedance matching would be important.

So for attenuating modular signal levels when going in to a line level input, use a simple resistive divider, eg. Voltage divider - Wikipedia

Alternatively, a lot of prosumer and professional gear can take modular levels directly on line inputs without attenuation. I think my previous Soundcraft mixer did, so I could just keep the channel level down. So if you haven’t already, it’s worth checking whether the modular outputs actually do overdrive the mixer inputs at minimum input gain, if you haven’t already. (Of course if you prefer attenuating before mixer for some practical reason in any case, then that’s another matter, just a thought that might save some work.)

(To clarify: not saying impedances wouldn’t still matter - just that in practise with standard line / modular devices you have low enough output impedance and high enough input impedance that you don’t really have to worry about it in the first place…)

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Following up on @kbra 's excellent answer, here’s that idea in action

In a simple way (also the post above this):
Norns - Audio In/Out Specs? - #39 by bmoren

and in a more complex way:

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Thanks for the helpful info. I did try into my mixer and unfortunately got distortion even with the channel gain all the way down.

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In that case, attenuator it shall be :slight_smile:

(And do remember, you can always use a normal potentiometer as a voltage divider as well, if you want a controllable one or aren’t sure yet what the best level of fixed attenuation is and want to try it out quickly…)

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Thanks! Isn’t the voltage divider you have there still a bit hot? Assuming 10v p-p on the modular side, that’s still 3v at Norns.

ETA: Duh. 10v p-p is 5v. So, that’s 1.5v at Norns. :upside_down_face:

3v p-p is still very hot for a line system powered at 3.3v, in my relatively inexpert opinion. When attenuating for, say, a guitar pedal, around 1v p-p reflects a guitar, for instance.

In general, might be worth making it easy to adjust any attenuation whilst you are fettling the levels.

Fair point about adjustability. I was planning to just make some really simple modular to line level cables with fixed resistors (and thus avoid having another box on my desk) but maybe the box is the right move.