View Full Version : Question about Pickups.

09-21-2011, 10:45 AM
My hearing is far from perfect. I mean bad. I took a chance and purchased a soundboard transducer for my Ukulele. Mounted it and am running it through a little Honeytone Amp.

But in order to get the volume up to the level that I would like a feedback loop is created. I've tried pointing the amp away from me and extending the distance between myself and the speaker. But get a lot of feedback still. I can plug earbuds in and avoid the problem. But with wearing hearing aids and such it get wearisome with something stuck in my ears all the time. I'd really like to use the speaker.

So I'm giving serious thought to mounting an undersaddle pickup into my Uke. I'm trying to decide if I should go with an 'active' or 'passive' pickup. An additional consideration is when I am traveling I will want to use something like this:


The reason I put this info in is that I don't know if a passive pickup along with the Headphone amp can supply the volume that I need to be able to hear clearly.

I've perused YouTube looking for videos that demonstrate this amp. One I found has samples connected to various guitars. Electric guitars with magnetic based pickups appear to give out sufficient signal to be picked up and amplified. The acoustic guitar in that video the volume seemed significantly lower then the other electric guitars. I don't know what kind of pickup it had though.

Long winded wind up to the question. Do passive pickups like Shadows put out the same power level of signal as a magnetic electric guitar? OR is their output more like what come out of a Mi-Si active pickup?

I'm trying to avoid having to have to use another amp like the boostaroo in line with the Vox type amp. Boostaroo is:


I do have an Eleuke Peanut and it pumps out enough volume. In addition it seems to be bulletproof. But it's not really a Uke that begs to be cuddled with. Wider bouts of conventional Ukes seem to fit me better.

You might be asking yourself why I just don't obviously go with the active Mi-Si pickup. I'm cheap. A passive pickup is $40.00 cheaper or there about and on top of it don't need to worry about running out of power on the pickup.

Did I mention my hearing is less then perfect?

Thank you for reading this.

Have a Great Day,

Rick Turner
09-21-2011, 12:48 PM
Preamps mated with piezo pickups are not necessarily about output level, they start off as being more about impedance matching.

This is an incredibly complicated subject and it's equally incredibly mis-understood, in part because it's...electronics...and in part because piezo pickups do not all share the same output voltage/output impedance issues. Some can be OK passive, all benefit from preamp buffering. Here's about as basic as I can get:

Piezo pickups make bad "line drivers"...they can be susceptible to voltage loss due to capacitive coupling within cable runs, and the high impedance nature of them as "sources" makes noise pickup along the way very much of a problem. Using a preamp to "buffer" the pickup signal as close to the source as possible minimizes line losses and noise.

Piezo ceramic pickups can be used passively under certain circumstances if the cable run to an amp is relatively short. The must, however, be plugged into a "load" impedance of at least 1 meg Ohm to preserve low end response. Piezo polymer pickups, often used for under saddle types, usually require both a higher load impedance...often 10 meg Ohm or more...and they usually need some voltage boost as well to get in the ball park of regular guitar output.

The quality of the first stages of preamplification are critical. The stuff I've helped design ( www.d-tar.com ) uses 18 volt on-board power for high headroom. If a pickup seems to require significant EQ, it's the fault of the pickup design or installation, not the concept of piezo pickups.

I could...and have...written major articles on this whole subject. Can't now... Must build some instruments. But that's as basic and explanation as I can give.

09-22-2011, 12:38 PM
I have a baritone Eleuke and just had a Mi-Si put in my Pono baritone. I really like the Eleuke but the tone out of my Pono is much more acoustic and uke-like. I run it through a Genz-Benz Shenadoah acoustic guitar amp and don't require any additional pre-amp. Plenty of tone and volume with a 16' cord running from uke to amp.

Just my observation of the differences I have noted with two ukes. Rick Turner actually knows WHY they might be different (thanks for the explanation).

Rick Turner
09-22-2011, 01:55 PM
I don't know anything about the pickup in the Eleuke, but the pickup element in the MiSi is (at least last I knew) actually made by Lloyd Baggs, and it's a very good piezo polymer pickup. The MiSi is on-board buffered, so no additional preamp should be needed unless you want some pre-pa or pre-amp EQ and control capability for handling signal processors or whatever.

I can tell you that installation will make or break a pickup installation totally independently of whether it's a good pickup or not.

Also, there are pickups, then there are on-board preamps, and a compromised preamp can totally negate the good aspects of a pickup design. I got to listen to four generations of Takamine preamp and one high headroom custom reference preamp using one guitar with the same pickup in it at Jackson Browne's studio. The pickup into a custom buffer running on 18 volts with NO tone controls was frighteningly good...and it then sounded worse and worse with subsequent generations of Tak electronics where they added features year after year...and lost good basic tone a bit more...year after year. The best Tak preamp was the simplest.