10Mohm vs 20Mohm for Dazzo pickups?

se7ent7 · #1 07-18-2016, 02:31 AM

Hi guys I emailed Teddy and he said the Dazzo's work with 1MOhm and 10MOhm, but he's not sure if they will work with 20Mohm...

(I want to replace the fishman matrix piezo in my Fishman Prefix Plus T pickup system of my Gibson Songwriter with the Dazzos, and continue to use the Prefix's barn-door pre-amp)

Isn't a very high resistance like 20MOhm basically the same from a pickup's perspective as 10MOhm ?

Are there any electrical engineers here who could help?

Is the "input impedance" specified in the user guide even the right value to look at - is that actually the input impedance into the pre-amp that the pickup sees?

Here are the specs for the Fishman Prefix Plus T:
http://www.fishman.com/files/prefix_...user_guide.PDF

jonfields45 · #2 07-18-2016, 07:07 AM

Quote:

Originally Posted by se7ent7

Isn't a very high resistance like 20MOhm basically the same from a pickup's perspective as 10MOhm ?

Are there any electrical engineers here who could help?

High is relative to the source (the pickup itself) impedance. There are plenty of reasons this might not work besides the load impedance; too little or too much gain, an equalization curve built into the preamp designed for the Matrix or UST's in general...

It is a worthy experiment and might be an excellent option for the many Fishman barndoors out there.

For a piezo pickup, if the the load impedance is too high, you will lose some of the high frequency response as the pickup itself, which you can think of as a small capacitor, straps the connection between the pickup and the preamp with a capacitor of smaller impedance than the input to the preamp. This strapping capacitance is somewhat similar to the tone control in an electric guitar and bleeds off highs. It seems unlikely to me that this will happen as I agree if 10M is not too much, 20M at 2x higher does not seem that much different in the logarithmic world of human hearing.

Doug Young · #3 07-18-2016, 10:15 PM

I posted a demo a while back of changing impedances thru the Grace Felix. The impedances were 1M, 10M, 10K, 1M, 20M, 330K. I didn't try a Dazzo, unfortunately, but I tried 2 other passive piezo's, the K&K and the Barbera. I wouldn't expect the Dazzo's to be significantly different in the degree to which impedance affects them. The thread is here:

http://www.acousticguitarforum.com/f...d.php?t=389063

se7ent7 · #4 07-20-2016, 03:05 AM

Thank you guys! Thanks Doug for that excellent thread! It seems the risk is small. I'm going to try it and report back.

Any Dazzo pickup size recommendations for a Gibson Songwriter Studio Deluxe EC (long scale rosewood *slightly smaller* dread) ?

I'm looking at the 70s currently....

varmonter · #5 07-20-2016, 06:35 AM

I can only interject that I have tried diff setups over the
Years.only when I bought a k and k equipped guitar did I notice
A diff.plugged into my sps 1 pendulum I never
Could warm up to the sound.....plugged into
A k and k pure xlr was a world of difference.
I know the pendulum is supposed to be the
Grail but I can only attribute this to impedance.
I have since bought a Felix.and switching the
Impedance switch to my ears makes an audible
Difference.

Doug Young · #6 07-20-2016, 09:03 AM

Quote:

Originally Posted by varmonter

I can only interject that I have tried diff setups over the
Years.only when I bought a k and k equipped guitar did I notice
A diff.plugged into my sps 1 pendulum I never
Could warm up to the sound.....plugged into
A k and k pure xlr was a world of difference.
I know the pendulum is supposed to be the
Grail but I can only attribute this to impedance.
I have since bought a Felix.and switching the
Impedance switch to my ears makes an audible
Difference.

Do you hear a difference between the "high" impedances Felix offers? 10m, 20m, 1m? Felix also offers some rather low impedances, down to 10k. That certainly causes a big change in tone. But no reasonable acoustic amp offers 10k impedance. (Id be interested in what you hear in the recorded Felix samples I posted above). Its surprising that you could not get a good sound out of an SPS1, but when it comes to sound, everyone has different experiences, and you're not alone in liking the k&k preamp. If it sounds good to you, thats all that counts.