Soundboard Transducer Feedback/Issue

mt8 · #1 10-23-2020, 09:50 AM

Just installed a soundboard transducer on my guitar. My placements for the sensors are as followed:

Between E and A, slightly towards A
Between D and G, slightly towards G
Between B and E, more towards E

The result? It is unusable without any EQ, tone wise it is good but suffers from feedback and boominess. According to the digital mixer I’m using, the problem frequency is between 150-200Hz and quick cut at that frequency fixes all the problems. Full gain cut at 180ish Hz and slight boost in the highs and it sounds alright.

Is it caused by my error if any in installation or is this something to be expected from soundboard transducers? I attached some pics and if someone can look over them for me that would be great as I’m unsure as to what qualifies as a good installation. The side with 2 bridge pins is the high E and 1 bridge pin is low E.

https://ibb.co/Qb10FHB
https://ibb.co/w0zJcb8
https://ibb.co/x79sMG4

And also, google tells me 200Hz is the G string but in actuality, the low E played open is the one causing the issue. Can anyone confirm that?

cmac · #2 10-23-2020, 10:12 AM

Low E is 82Hz, so when you cut 'around 180Hz' then perhaps the problem is with the 2nd harmonic at 164Hz.

Also it's quite possible your guitar has a natural resonance that is causing a peak in the pickup output that you don't necessarily hear acoustically.

My experience of K&K pickups is that I have had to reduce the low-mid range a bit. Some of the is due to the sound profile of the guitar, which is cedar on rosewood, a natural producer of low-end rumble.

So I don't think what you are experiencing is particularly unusual. I think it's rare for a SBT to be perfect with flat EQ.

Mandobart · #3 10-23-2020, 10:44 AM

Any SBT can turn the whole guitar into a mic no matter how and where its installed. Speaker placement is crucial. The only times I've had feedback issues are when I'm standing and playing right in front of a main, or I have a loud monitor pointed right up at me.

I have SBT's installed on 4 fiddles, 7 mandolin family instruments, and 6 guitars. I either play through my Carvin AG300 or a RedEye into the house. I've never had to do any special eq (like notch out a freq band) with any of these.

jonfields45 · #4 10-23-2020, 12:35 PM

All acoustic guitars have a resonant peak between 100 and 200 Hz. Your result is par for the course. That you've found an easy single notch filter fix is why that sort of filter is included in many acoustic guitar EQ pedals.

shufflebeat · #5 10-23-2020, 01:12 PM

Quote:

Originally Posted by jonfields45

All acoustic guitars have a resonant peak between 100 and 200 Hz. Your result is par for the course. That you've found an easy single notch filter fix is why that sort of filter is included in many acoustic guitar EQ pedals.

+1

Random words to fulfil character count.

Vancebo · #6 10-23-2020, 01:57 PM

SBTs are very susceptible to the very thing you describe and are experiencing. Those transducers are a cookie cutter approach and if you super glued them in, I am afraid you cannot remove all three of them safely with damaging at least one unless you get super lucky.

In my experience, a hi pass filter is a great tool to get you to a good starting point. One set at 80hz most likely won't be good enough. An adjustable one that can be set until your ear says "that's it" would be best. I often have set mine up to 120hz to 180hz mostly when I am playing in a band situation. Your pickup type likes an input that has a 1M ohm impedance. If your gear is a 10M ohm input then you may experience a larger bottom end. Some DIs are 500 ohm input and may cause some of that low end to really drop off. The 1M ohm is a happy spot. It's something to investigate.

I have always liked a good floor preamp unit that had all of the tools I need at my disposal. I don't always use all of the tools but it's nice to have. Three band EQ with adjustable mid frequency, Hi pass filter, boost switch, mute, etc.

If you are set with your pickups. Here are three possible solutions:

1) Tonedexter Preamp. This will take care of your problem and get you a good mic'ed sound.

2) Get a floor preamp (described above) that has an adjustable hi pass filter and any other features you find important. I prefer the Sunnaudio MS-2. It's spendy but it's the cleanest and warmest I have tried. There are others too.

3) I wonder if you could visit the James May website and look into the Ultra Tonic Pickup. There may be a way that you could use your pickup and add his electronics to it for it's feedback suppression abilities. I think he has a way to add it to a K&K. I believe it may require a battery in your guitar.