Installing a Disc-type Passive Piezo Pickup

Wiggy

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Kamemeha SP-10 Ukuele

2 Mar, 2023

- Received (eBay) a 3-pickup (dot) Passive system with a combination endpin/strap-button jack.
Universal Pickup Piezo 3 Transducer 6.35mm For Acoustic Guitar Ukulele Mandolin
$7.47 shipped

I intentionally bought the "guitar" version as the wiring is longer.
The 3 pickup dots are wire-or'd (in parallel) to a long lead going to the jack.

- Also purchased a Behringer ADI21 (looks unused in open box.). $34.64 shipped

Will need to use only 2 of the dots as on this uke there is a vertical brace that is perpendicular from the bridge to the horizontal brace before the soundhole. Will cut the wires to exact length and will likely solder the 2 dots directly to the jack as it looks like their wires are long enough.

(I probably would have gone with a single pickup if there wasn't a verticle center brace.)

- - -

Cut off one of the pickups, and used a magnifying glass to make certain the cut was clean and didn't result in a short.

Used sticky clay to "EKG" test dot positioning.

Will install pickups 1/2 way between the bridge and the horizontal brace with the outside edge of pickups aligned with the bridge width.
It will be an easy reach to place both of the stick-on dots.

- - -

Amplfifed test

Plugged it straight into an old-school Peavey Pacer (with a modern Blue Marvel driver) and it did not need a preamp for gain. However, like all piezo's the tone is squawky and way out of control.

Tried a TC Electronics Mini Spark and that nicely tamed (buffered) the piezo. The amp's EQs were then easy easier to dial in for good acceptable tone. One has to be careful to not add any gain with the M-S as the peizos already are plenty loud. Use it just as a buffer.

I then tried a Donner Guitar EQ (6-band with volume balance) and that really helped!

Gain midpoint
100hz boost 1
250hz 0
630hz cut 1-1/2
1.6khz cut 2-1/2 (all the way down)
4khz boost 1

- - -

Mute switch?
Now that I have an ADI21 I no longer need a mute switch. End of topic.
 

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... Oh my. I just tried sticking this in the same position on a concert and on a tenor. It really sounds good on all of them. Even on a Flight TUC-55. It will likely be the next "convert."

I may order several (3) more after I finish working out a mute button and complete this installation.

<edit> OK. Shorting the piezo output mutes the sound and does not create a "pop." More like a tiny click...
Good so far, but will shorting it hurt the Piezo pickups?

<edit-2> I have since read that piezos are electrically bidirectional so I don't think they can be damaged by a short across their 2 terminals.
I'm going for a simple shunt switch. TBC,...

<edit-3> Now that I have an AI21 I no longer need a mute switch. End of topic.
 
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Received the "open box" ADI21.

This is what I needed. It does everything (Buffer/EQ/Gain Control) Bill Sheehan says it does, and it is affordable.
(The Donner G-EQ also did well, but the ADI does it with a lot more finesse.

Ding! Ding! Chicken Dinner.
Ordered 3 more piezo kits.
 
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+1 for those. I've always had pretty good luck with those cheap eBay piezo soundboard pickups. I've installed a JJB, but could not tell the difference in sound between them. I suspect you get more defective ones for $1-$2 eBay ones, but I always test them first. I have always needed a preamp with EQ to tame the quack. Fortunately, my acoustic guitar amp has built in pre-amps but I too have used to ADI20 successfully on those that don't.
 
Received the "open box" ADI21.

This is what I needed. It does everything (Buffer/EQ/Gain Control) Bill Sheehan says it does, and it is affordable.
(The Donner G-EQ also did well, but the ADI does it with a lot more finesse.

Ding! Ding! Chicken Dinner.
Ordered 3 more piezo kits.
Glad you're having good results with your Behringer preamp/DI, Wiggy! I really like mine. I've been using it for ukulele and also six-string acoustic guitar on occasion. So far I've gone strictly with a 9V battery, and the battery life has been decent. I always have to remind myself, however, that plugging an instrument cable into the preamp's "IN" jack activates the battery and will drain it quickly if not unplugged in between uses!
 
I'm glad I found this thread just now, because I am considering buying a uke bass and would also buy a preamp/DI box too. @Wiggy, you said in your post that you no longer need a mute switch because you use the Behringer ADI21. Why is that? Does the Behringer have an on/off button?
 
I'm glad I found this thread just now, because I am considering buying a uke bass and would also buy a preamp/DI box too. @Wiggy, you said in your post that you no longer need a mute switch because you use the Behringer ADI21. Why is that? Does the Behringer have an on/off button?
No. The ADI21 has a "bypass" mode switch that alternates between:
  • an active DI buffer (taming the piezo harshness and correcting impedance match)
  • all that, and the added EQ/Modeling enhancement.

A passive piezo pickup in its simplest form does not even have a volume control. So having a mute button would have been for my own convenience. The U-Bass (if it requires a battery to work) will have its own volume, tone controls, and buffering so it can be plugged into any mixer or amp.

What will you be plugging the U-Bass into? Before purchasing the ADI21, you might wait to determine if it's really needed.

If you have a need to use a balanced XLR to connect to a PA mixer the DI part of the Behringer will also do that.
 
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Thanks for the quick reply, Wiggy. If I buy one, I am going to outfit it with a passive pickup. I would be using it mainly for musical theater gigs. I can't rely on the built-in active pickup in the bass ukes because they use those little button batteries, which wouldn't even last two nights (I have to leave my bass plugged in for up to four hours each evening, for several evenings in a row). With a passive pickup, going into the house sound system, I will definitely need a preamp/DI.
 
...I can't rely on the built-in active pickup in the bass ukes because they use those little button batteries, which wouldn't even last two nights (I have to leave my bass plugged in for up to four hours each evening, for several evenings in a row). With a passive pickup, going into the house sound system, I will definitely need a preamp/DI.
The active DI's XLR output will drive at least a 100 ft. balanced cable. Keep your 1/4" TS (normal guitar) cable to the DI as short as possible.

You should search other forums for players (performing arts theaters?) who have this same requirement.

Try posting on the TalkBass forum.
 
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The DI will be on the floor, right next to me, so my cable will only be a few feet. The house sound guys have very long XLRs to go from the box to their sound panel. Thanks again, Wiggy. Appreciate the info about the Behringer etc. Still not sure if I'll get one of those bass ukes, but will decide soon.
 
After realising it is pointless selling a perfectly good, untrendy solid mahogany concert to find an instrument with a pickup, I've invested £4.22 in a double piezo pad to come from China - to try. I was going to try a Double C1U (£30 but perhaps thats a ringer version) or a C2 (£39, ditto), but I've got enough batteries to replace in the house already... and someone made a good point about keeping as much hardware out of an acoustic void as possible. If they don't work after a week, I'll buy a decent well reckoned version.
 
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After discovering the pickup in my Aquila bass was just one of those brassy-edged discs going straight to a standard 1/4" jack I bought several different sizes of the same piezo elements to install in various instruments and made several paired double piezo pads to install on the underside of the soundboard with double-sided tape; they do work, although you will need an external pre-amp it has to be better than cutting a hole for an onboard preamp in a beloved uke and then finding it hard to source a replacement several years down the road!
 
I'm kinda presuming they will work with a coolmusic 10W box, which has bass, mid and high adjustment and a few other jazzy bits on the instrument feed. The Risa system is ok and that's no batteries. But I'd like to get to a position where I can play normally/simply things with a group and just amplify where a song lead is needed - rather than un-asked for! I hadn't realised that you can't really ascertain the right volume for your own amped RISA until people say 'very nice, but perhaps turn it down a bit?' Oops.
 
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