Guitar pickup tests


#1

Hey,
So I am exploring what kinds of pickups to use. All violin pickups are currently piezo based. As in a crystal that takes vibrations and turns them in to sound (same goes for microphones but using the air as a medium).

I can only see people on the internet using magmatic based pickups in the early 2000’s and then its abandoned, probably because piezo gives a sound similar to acoustic violins.

However a magnetic pickup gives a different sound, a bit like a guitar, so here are a few tests. I took 3 humbucker pickups.
I didn’t electric shield anything like you should so apologies for the buzz. The sound was recorded out of a Behringer V amp, so what you are hearing in the video is the pickup, no microphone.

Strings are Coated steel core, nickel chromium wound, E string is stainless steal core.

Test 1:

Test 2:

Test 3:

Would value feedback and ideas what to do next


Post about why I set up this community
#2

That sounded better than I expected. So, are those guitar strings, or are there violin strings with metal cores? I’m a guitar player, but I recently bought one of those cheap electric violins, and was thinking, I could probably make something like this. I have a CNC router and already built a few guitars.


#3

They are super cheap violin strings, coated steel core, nickel chromium wound. I also got some steel core, nickel silver wound ones. So hope to compare against that later on.

I also have high end D’Addario Helicore which acoustically definitely sound better, but haven’t tried them yet with the pickups. I want to figure out how to ground it all first.


#4

I might have a solution!

I’ve been stacking inductors and small magnets to make individual pickups. I boost the passive output with a phono preamp. A phono preamp is sort of already designed to boost a small signal from an electro mechanical coil system. The pickup is very cheap and can be made multi-channel.

I have a four string guitar that I tune to fifths like a mandolin/violin. I use a stereo phono preamp and separate the first and third strings from the second and fourth. https://www.youtube.com/watch?v=jvMHfpch2dw

I think the sound quality is fairly excellent considering how cheap it is to make. I have some details on the inductors used on my site here http://bingweb.binghamton.edu/~cschreco/devices/devices.html#Duophonic


#5

Interesting, though I am not sure a phono preamp would would have the connect response to a single instrument input. But I might be wrong, I havn’t played with them enough.
I’d love to hear how it sounds with a bow.

I found so far the main issue with pickups in general is that they tend to like resonance. Guitars are usually plucked creating a shock across the string, and it means you are less prune to feedback loops. So it would be interesting to hear how these strings sound when you pull a bow across them. You can hear the difference in my test videos of how the string sounds when its plucked or when it has a bow going across it.

You can see how how a violin sound wave looks like. BTW, you can tell which way the bow goes from it!:


(source)
Its prune to resonance.

A guitar one looks like this:


(source)
Much less chance of resonance.
(Note: there is a time scable difference between the graphs)


#6

I believe in this case the inductor/magnetic + phono preamp will serve you well.

Guitar pickups have that resonant peak. Different pickups put the peak at different frequencies and it contributes to the honk of a pickup.

Whereas the phono preamp is designed to be flat enough besides the RIAA curve? Anyway, a phono system definitely doesn’t include a deliberate resonant peak. I used the phono preamp to treat the output of my toy piano magnetic pickup project and the results were excellent. The system had a clear resonant peak at the high F key before I used the phono preamp. With the preamp, the ringing at F went away totally. https://www.youtube.com/watch?v=8FRj3I-THKQ There are issues with this demo, but the results were striking.

I can appreciate the difference between bowing and a pluck, but I’m also very familiar with how it feels to play through a system with a resonant peak. The way it causes over-articulation of notes that are harmonic multiples of that frequency. In playing with the custom pickups through the phono preamp, I can move chords and voicings around without getting thrown off by a resonant ring.


#7

Is there a way we can test it with what you have?
I sounds promising, but it makes more sense to test it with your equipment that you know, than me trying this, unless you have easy assembly instructions. At least so we get a initial proof its a good direction.


#8

Let me try to borrow a bow from my friend! I will record the result directly. I may ask him to help with the actual bowing. He is an experienced violinist.


#9

Remember to record if you can!


#10

I did this test with an old bow w/o rosin. My technique is of course horrible. The instrument has a scale length of about 572mm. The first two notes are farther up on the neck of the instrument. The rest are closer to the bridge and the pickup. I think there is self-modulation distortion from the pickup being too close to the strings.

On Monday I should have an opportunity to mount one of these pickups on an actual violin and my friend will demo.


#11

Seems like a clean sound, slight clamper in the wave form. lots of overtone. When you pull the bow, it needs more rosin and the right force

Here is a comparison with @Carl_S on top and test 1 at the bottom, both are A down bow


#12

https://youtu.be/gZXOPT8sRRo

Here’s another test on an acoustic violin.
We didn’t mount it very solid, so the pickup is sliding around during the recording
the pickup I used prevented bowing in the normal position so it’s being bowed uncomfortably up the neck. The pickup’s also flat.

finally, we used a very bad mixer to pull the stereo signal down to mono. I believe the noise in the recording is largely from this mixer. The noise is not characteristic of what I get when I run the pickup into amps/recording normally.

My buddy asked me to fabricate a pickup assembly that will arch properly to meet the middle strings. He was really pleased with the sound we were getting even under the bad conditions.


#13

Thanks for sharing all these tests! Carl, I really like that four string guitar you set up. I was wondering recently about guitar pickups, so this is helpful to scroll through. Keep testing!


Jeremy's build - 2018
#14

Thank you! I hope to have an arched version to mount on a violin by the end of the week. And a guide for a guitar version soon after.

I want to mention for a moment- the pickup is very inexpensive. I used a pack of 1/8" circular neo magnets. I believe it was a pack of 50 magnets for under 10 US dollars. The inductors I used were Digikey #495-5616-1-ND. They are available for individual sale and are right now 0.96 US dollars a piece. If you can mount them in scrap and have some glue lying around, you are there.

Phono preamps are so much cheaper than serious instrument preamps. In this application, I believe the RIAA curve is complementary. (The pickup functions passively, w/o phono preamp, but it is shrill and weak, noisy)


#15

BTW, I have been playing with the humbucker during the weekend, and it seems like you can’t tell that well the direction of the bow. That is the phase is really similar to how the microphone graph looks. It seems inductor-magnetic gets a clearer signal. However a humbucker does buck the hum by design, so it might have less noise.


#16

Just some input from me. Since I played around with this quite a bit and decided against this style of pickup.

Guitar pickups have a linear response to an input. To get the loud dynamic, you have to put an exponential amount of force greater into it, because humans perceive sound more or less in a logarithmic decibel fashion. You can use a compressor obviously to get more dynamic, but there are unintended consequences to its use, and may make the sound a little wishy washy.

Also, using a guitar styled EMG pickup suffers from resonance. (three forms of resonance: electrical coil, feedback coupling, and string). The string resonance is formed when the standing wave pattern is created based on the frequency of the played note. This creates harmonic nodes that don’t “move” as much. The electrical coil resonance, isn’t too bad; as long as you have enough capacitance and low current. The feedback coupling is just from ambient electrical signals like the 60hz hum, and from other sources.

Piezo pickups respond more “natural” because of the mode of transmission into the device. The radical acceleration changes are what allows for that logarithmic change in output.

Anyway, long winded, but I hope I highlighted some hurdles you may face in future tests.


#17

That’s an interesting point. I wonder if the loud dynamic can be compensated somehow. For example I had this craving to try and connect a controller to the bow and use its movements to control effects. Perhaps the bows speed could be translated to a volume expression pedal, by responding to it and not directly to the mechanics, and providing the dynamic range.

I am in the process of finishing another violin and attaching a guitar pickup, so I will update if I bump in to this problem.


#18

Looks like Cantini use magnetic pickups:

(Released two months ago, a few days after I started the thread)

They even sell kits:

http://www.cantinielectricviolins.com/2/online_shop_prices_3390630.html

They say its a “Inductor Separate Sensor Pickup ISSP2 Separate magnetic pickup for each string”


#19

Ok,
I’ve been doing some digging. Apparently searching for patents is an excellent way to find magnetic pickups for violins.

Separate post on that