• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Double Bass How to make a piezo pickup

#62
Cool !
I have looked into the ready made coil idea as a time/money saver , Choke coils and inductors can work too.
Unfortunately the suitable ones I found were only sold 500 at a time! Most had too low dc resistance and the wrong (less desirable magnet) also There was a tonal issue too. the machine wound coils build up an unpleasant capacitance due too the very even winding, I found by scatter winding the coils i get a much more complex and desirable sound ( don't really understand why)
I do as you mention alternate magnetic polarity N S N S
or the opposite for humbucking and phase correlation.
I thought about the preamp Idea but found it cost and labor prohibitive.
I should have photos and finished models by april.
I am hoping to make one for A tour in march with one of my groups www.taarka.com .
The working prototype i have now truly looks like a BORG!
8 wires plus a ground wire mounted on a piece of fiberboard.
That wont' hold up on a tour!
Once i get my drill press I can make the completed fully shielded enclosure which will match the ebony fingerboard.
right now i am planning on using copper foil for shileding which has worked on single coil model but conductive paint would be ideal. Any of you folks have experience with that stuff?
Good luck and thanks for the conversation.
JFLO
 
#63
mje said:
Never thought of doing my banjo!

Aren't you getting a lot of hum on that unsheilded pair coming from the piezo under the banjo bridge? Also, what kind of preamp are you using with the Kynar film element?
Click to expand...

Not much hum from the pickup but I don't have anything more powerful than my 15 watt Peavy practice amp. The guitar amp that I let my son use is only 10W :) This is to keep my wife happy (and not killing anyone). I've even considered putting up the Soundtube speaker in the den so we can watch a movie in peace...

As far as a preamp, no preamp but he is usually using a pedal when playing it. The banjo piezo pickup is really only experimental and if he were to gig with it I would have to rebuild the thing - It is only stable in the seated and unmoving possition, otherwise there is a lot of noise from even patch cable movement. Honestly, a stupid yet fun thing to do...
 
#64
jflojazz said:
...
right now i am planning on using copper foil for shileding which has worked on single coil model but conductive paint would be ideal. Any of you folks have experience with that stuff?
Click to expand...

Krylon makes a spray-on magnetic board paint that's mostly iron particles. Word is that it's very conductive and makes a good spray on shield.

I've found that the 3M copper tape with conductive adhesive is very easy to use. My other choice is .005" brass shim stock of the sort sold in hobby shops- I picked up a bunch cheap on Ebay.
 
#65
thanks MJE
I will try the krylon. I have conductive tape from stewmac but it is not ideal for the twists and curves of my current housing.
Thanks
Wait! I just realized that magnetic paint will interfere with the magnetic field of the pick up . I need a non magnetic shielding like copper or brass. Thanks for the idea though
JFLo
 
#68
Passinwind said:
You can get a graphite based one here: Stew Mac Shielding Paint.
Click to expand...

From the Stewmac website: "Conductive Shielding Paint
The fastest and easiest way to shield pickup cavities, control cavities, cavity covers, and other smaller areas. Water soluble until it dries."

This stuff works well but is only suitable for internal cavities where it won't get rubbed off. It's not durable enough for external shielding.
 
#72
dleblanc said:
I'm just about to get into upright and I wanted to get a pickup in order to plug into a rackmount tuner and make sure when I'm playing, I am in tune. Will this be sufficient?
Click to expand...
Just about any pickup would be fine for that application, including these DIY piezos. You wouldn't need a preamp.
But why not just get one of those nifty little clip-on tuners that would be a lot simpler?
 
#73
ToneRanger said:
Just about any pickup would be fine for that application, including these DIY piezos. You wouldn't need a preamp.
But why not just get one of those nifty little clip-on tuners that would be a lot simpler?
Click to expand...

Because I already have the rack-mount tuner... :D

I was wondering... can you play an upright through a electric bass amp? Well, I'm sure it won't hurt the speaker, but will it sound bad?
 
#74
Check the input impedance on your bass amp. If it is 1 MegOhm or higher, you are good to go. Otherwise, you need a preamp. What kind of amp is it?

You won't damage the amp, but you also won't get the best sound if your amp has a lower input impedance. It alters the frequency response in a way that: a) Makes your bass sound worse; b) increases feedback problems.

The preamp needn't be fancy, and it doesn't even need any knobs -- its main job is to go from the high-Z output of your pickup to the lower-Z input of your bass amp.
 
#75
fdeck said:
Check the input impedance on your bass amp. If it is 1 MegOhm or higher, you are good to go. Otherwise, you need a preamp. What kind of amp is it?

You won't damage the amp, but you also won't get the best sound if your amp has a lower input impedance. It alters the frequency response in a way that: a) Makes your bass sound worse; b) increases feedback problems.

The preamp needn't be fancy, and it doesn't even need any knobs -- its main job is to go from the high-Z output of your pickup to the lower-Z input of your bass amp.
Click to expand...

It's a Hartke Model 7000... I don't have the manual for it. It was my guitarist's basement, but I think he threw it out. I'm not sure what the input impedance is.

It has an input for passive and active pickups. Are these two different impedance levels? I'm not really too great with the technical aspect of amps and such. I'm going to guess it's higher for active pickups... Am I right?
 
#76
Use the passive input - it's probably just a bit more sensitive. It may work fine without a preamp but you'll need to keep the lead fairly short. Like fdeck says, all the preamp has to do is buffer the impedance - maybe you can patch in an fx pedal that will do it for you.
And I can recommend fdeck's little DIY preamp - if you have basic soldering skills they're easy to make.
 
#77
Pretty basic/stupid beginner question: if I'm making piezo pickups according to this design, will the jack end be sufficiently shielded if I attach a 1/4" plug with a metal barrel to the end of the mogami cable? Or would I still need to cover that in copper foil as well?
 
#78
pklima said:
Pretty basic/stupid beginner question: if I'm making piezo pickups according to this design, will the jack end be sufficiently shielded if I attach a 1/4" plug with a metal barrel to the end of the mogami cable? Or would I still need to cover that in copper foil as well?
Click to expand...
Should be OK without, but I've found that the slightest gap in the shielding will generate hum, so I tend to shield everything in sight.
Make sure you keep the lead as short as possible for best performance - building fdeck's buffer/preamp right onto the pickup is the ideal solution, although I've had no problems with standard guitar leads into my Eden amp.
 
#79
ToneRanger said:
Should be OK without, but I've found that the slightest gap in the shielding will generate hum, so I tend to shield everything in sight.
Make sure you keep the lead as short as possible for best performance - building fdeck's buffer/preamp right onto the pickup is the ideal solution, although I've had no problems with standard guitar leads into my Eden amp.
Click to expand...

I've lately been building the phantom-powered version of the Don Tillman preamp right onto the sensor. You only need to put a transistor and two resistors there, which doesn't take up much room, and you can plug stright into a phantom powered front end, or a battery box. The preamp gives you 6dB of gain, too, which these film MSI sensors really need.

The ideal way to do it woiuld be using surface-mount componants. I've been trying to do this with some surface-mount J201 FETs I bought, but even with the 13 watt soldering iron, a 1/16" tip, and my fly tying skills I can't quite do it. We'll see.
 
#80
I've just installed one of these pickups under the bridge E foot, and it sounds great!
The only thing is, output is a little low. Is that typical?
The best sound seems to be with a piece of wine cork (merlot) under the pickup, as suggested. I'm using a wood shim to fill the rest of the gap, and running through Fdeck's great little buffer-preamp.
Anything I can do about the installation to increase output? I tried it in the wing slot, which was strong, but wrong.
 

Latest posts

Top Bottom
Back