Do you HAVE to power a piezo pickup?

[fretlessman71]

I'm looking at installing a piezo pickup on my fretless Wishbass, and I had designs of cutting it lengthwise - like a hot dog bun - and placing the pickup there, and letting the pressure of the strings on top create the pressure necessary for the pickup to work.

A few questions:

Am I going to need to get an active preamp for the piezo? Are there certain types of piezo pickups that work well and thrive just as they are?

Is there anything special I'll have to do in order to be able to blend this pickup with my magnetic pickup?

Is there anything you can think of that I'm not considering? (I've already figured out how I want to get the piezo wire to the electronics cavity.)

Thanks in advance, TB - you're the best!

[Mutant Corn]

I'm no specialist, but if I remember correctly they have very low output without a preamp.

[chicago_mike]

you need a buffer stage. Nothing more. you could do it with an external mic pre...most of the time.

Bartolini has a simple piezo buffer. Cheap too. =)

[bongomania]

A piezo can certainly work without an onboard preamp, but it may sound terrible (potentially noisy, low signal level, loss of highs) unless the cable distance is fairly short and/or the input impedance of the amp is very high. A preamp is a buffer, which corrects the impedance problem and typically also provides signal gain.

[fretlessman71]

"Me no speaka-de Ingliss!"

Seriously - I've never heard of such a beast, but it sounds like what I need, AND what I need to know. Please elaborate...?

[chicago_mike]

a buffer or preamp will change the impedance of the piezo crystal. thats about it, kinda sorta. Its so you can get a good signal to the outboard gear. More fancy answers will cost you a klondyke bar.

[fretlessman71]

Originally Posted by chicago_mike

a buffer or preamp will change the impedance of the piezo crystal. thats about it, kinda sorta. Its so you can get a good signal to the outboard gear. More fancy answers will cost you a klondyke bar.

This good enough?

[bongomania]

OK, I'll see if I can clear this up. An audio signal is energy. Energy can be labeled and measured in all kinds of ways like volts, watts, etc.; but if there's a poor connection between where the energy is coming from and where its going, then it doesn't matter how much volts/watts/etc. you have, a lot of that energy is going to waste. Just imagine a broken bicycle chain- you're pedaling and pedaling and not going anywhere. In a less extreme example, you're riding uphill in the wrong gear. You are straining and struggling and putting out a ton of energy, but you're not getting uphill anywhere near as quickly as you would if you were in the right gear. You need a more efficient energy transfer between your legs and the road.

Impedance can be described as the efficiency of the transfer between two devices. Every output has an "output impedance", and every input has an "input impedance". If the relationship between them is not ideal, you lose tone, you lose signal level, you lose highs, and you may get noise after turning up the gain to make up for the lost signal.

The ideal relationship between two devices is typically a very low output impedance and a very high input impedance.

Piezo pickups have a high output impedance (compared to regular pickups), so their signal doesn't usually transfer well to a typical bass amp input. In order to get the most out of them, you either have to get an amp with an unusually high input impedance, or use an onboard preamp to lower the pickup's output impedance. That's one of the main things an onboard preamp (AKA buffer) does, is lower the output impedance of the pickups.

Just like bicycling uphill in the wrong gear, it can be done, you can use a piezo without a preamp into whatever bass amp; but there's a better way.

Just to be clear, making it simple, you do want a preamp in there, or at least a booster pedal of some kind (even a basic EQ pedal) to lower the impedance before it hits your amp.

[fretlessman71]

Dude, you're good. This is making sense now.

Okay, so I need SOMETHING onboard to essentially "power" the signal from a piezo pickup. And I've checked into the Bartolini buffer mentioned earlier in the thread, and it's about $90. I'm good there.

So the next question:

Is it even remotely feasible to find a way to simply power the buffer without having an onboard preamp? I'm really trying to keep this bass sounding as organic as possible, and I already have a tone circuit purchased and waiting to be installed.

[Marcus Willett]

Originally Posted by chicago_mike

you need a buffer stage.

Originally Posted by bongomania

A piezo can certainly work without an onboard preamp, but it may sound terrible

Originally Posted by fretlessman71

so I need SOMETHING onboard to essentially "power" the signal from a piezo pickup.

No, you don't. Dave Wendler makes piezo equipped basses that are completely passive and sound great! I have the first 5 string he ever made and without exception every time I use it I get compliments on the sound. Very organic and woody and just as hot a signal as any passive bass...actually a bit hotter than most. Check him out; you'll be gald you did.

NCI at all, Dave is just a buddy who makes good stuff!

[bongomania]

Here's the thing: a buffer is a preamp and a preamp is a buffer. Really the Bartolini buffer is just like one of their preamps without any EQ controls. It's like buying a preamp and then leaving all the EQ controls set flat.

If the tone circuit is a passive device, then you'll want to consult the maker about the best way to connect it to your pickup(s) and the buffer. If it's an active device (needing power) then it's a buffer already.

[fretlessman71]

Originally Posted by Marcus Willett

No, you don't. Dave Wendler makes piezo equipped basses that are completely passive and sound great! I have the first 5 string he ever made and without exception every time I use it I get compliments on the sound. Very organic and woody and just as hot a signal as any passive bass...actually a bit hotter than most. Check him out; you'll be gald you did.

NCI at all, Dave is just a buddy who makes good stuff!

Okay, so which song on your myspace page features the bass in question?

[bongomania]

Originally Posted by Marcus Willett

Dave Wendler makes piezo equipped basses that are completely passive and sound great!

I believe you, but that necessarily means either he has come up with his own fancy method of passively altering the output impedance, or your amp or DI happens to have a high-enough input impedance to make it sound good.

[chicago_mike]

Could be done with transformers I think, but...I had the bart unit in a conklin I had and like it a lot. ANd all I had after that was a passive tone control.

R-C-I circuits could alter the impedance, but I worry about the passive load. But thats just me.

Ty for the Kooties infested klondyke!

[fretlessman71]

Originally Posted by chicago_mike

Could be done with transformers I think, but...I had the bart unit in a conklin I had and like it a lot. ANd all I had after that was a passive tone control.

R-C-I circuits could alter the impedance, but I worry about the passive load. But thats just me.

Ty for the Kooties infested klondyke!

Hey, only GIRLS have Kooties. I'm a fretlessMAN, don'tcha know.

[IanStephenson]

Originally Posted by bongomania

OK, I'll see if I can clear this up. An audio signal is energy. Energy can be labeled and measured in all kinds of ways like volts, watts, etc.

Not to be pedantic ;-) but enery is ALWAYS measured in Joules (or maybe calories if you're on a diet).

Volts is a unit of "Potential Difference"
Watts is a unit of "Power".

Power (Watts) is the rate at which energy is generated/tranfered 1 Watt=1 Joule per second.

The basic problem with Piezo's you're taking the Energy in the vibrating string, and using it to squeeze a tiny crystal which turns it into elecrtrical energy. It's a tiny crystal, so it doesn't generate a lot of energy in a given time period (ie it produces very little Power). That's hardly surprising - it's a tiny crystal. Because there's not much power in the signal you need an amplifier. Because the signal is so low powered you want the amp close to the pickup, so the signal doesn't get corrupted.

Electrical power needs volts and amps, so that amplifier can increase power by increasing voltage and/or current to a level needed by a regular amp. It could even swap some voltage for current (or visa versa), keeping the power the same to better match the amp.

Ian

[-Sam-]

http://www.windworld.com/products/catalog.htm#hardware
http://fittell.id.au/piezo/

[PilbaraBass]

Originally Posted by IanStephenson

Not to be pedantic ;-) but enery is ALWAYS measured in Joules (or maybe calories if you're on a diet).

Volts is a unit of "Potential Difference"
Watts is a unit of "Power".

Power (Watts) is the rate at which energy is generated/tranfered 1 Watt=1 Joule per second.

The basic problem with Piezo's you're taking the Energy in the vibrating string, and using it to squeeze a tiny crystal which turns it into elecrtrical energy. It's a tiny crystal, so it doesn't generate a lot of energy in a given time period (ie it produces very little Power). That's hardly surprising - it's a tiny crystal. Because there's not much power in the signal you need an amplifier. Because the signal is so low powered you want the amp close to the pickup, so the signal doesn't get corrupted.

Electrical power needs volts and amps, so that amplifier can increase power by increasing voltage and/or current to a level needed by a regular amp. It could even swap some voltage for current (or visa versa), keeping the power the same to better match the amp.

Ian

Joules is not the ONLY measurement of energy...Nor is calories..I measure energy in Kid-seconds...

1 Kid-second = 10,523,421 Calories...

[IanStephenson]

Originally Posted by PilbaraBass

Joules is not the ONLY measurement of energy...Nor is calories..I measure energy in Kid-seconds...

1 Kid-second = 10,523,421 Calories...

But only parents and astro physicists needs to deal with THAT much energy

;-)

[chicago_mike]

I would know, but I cant even spell Klondyke! =)

Klondick...nope

Klondik...close!

Klapdi.....nooo

dangit!