Piezo pickup buffer

[sonic66]

Hi, i had a go at building this buffer box for a piezo pickup.
http://www.scotthelmke.com/Mint-box-buffer.html

Firstly i had the source on the fet going to the 9v not the out put but corrected that. I'm building it for a friend who is using a piezo for a double bass on his acoustic

I just want to know how to tell if its working properly?  ther does seem a small difference o9n the guitars i have . may be less thin mabe overall less bright - not worse.

I've heard my frienfd using his acoustic  with the piezo through a P.A before, with out a di and it did sound very scratchy.

Should this buffer if working properly make a big difference to his sound?


Anyway it seems to be a usefull resource and here is another usefull link(s)

http://www.cafewalter.com/

http://www.cafewalter.com/cafewalter/projects.htm

[sean k]

Hey Bro,why not increase the output cap to about .47 and see what happens?
 This what I've always used for piezo's


I'd say the thing is that because its a double bass you gotta have high passes way down to a few Hertz and maybe even some low pass at a few hundred Hertz plus that really high input impedance which I suppose needs to be higher the lower you go.

[Paul Perry (Frostwave)]

I wouldn't expect a great difference, unless you are driving an effect that 'expects' to be driven by a certain imprdance.
Where it would make a huge difference, is if you were driving  long cable, if a piezo goes straight to a long cable then the capacitance fo the cable sucks out all the highs. I have had to make buffers for people putting piezo contacts on percussion stuff.

[sonic66]

Thanks Sean,

He played using the buffer box last night straight

Was hard to tell if it help the sound as i didnt get a chance to hear him play for more than briefly without it.
The sound was pleasing, though  he'd spent some of the afternoon tweaking his sound with the amp alone.

I may get a better chance to see it in full flight with a  double bass. I could add a switch to select between .1 and .47 to see what works the best. This player has played through a ROG Fetzer that i'd built and wanted me to build one for him.

Thanks for your post . I could have a go at it too.

Paul, I read some other posts about di's and buffers and   in this instance it sounds like a a buffer is acting the way a di would ( though not bal/ unbal stuff).  

If using a di before a stage box-multicoil-mixer setup would there be any need for a buffer OR if a using a buffer like this one is there any need for  a di befor the stage box? How long is long? 10ft + ? When / where do most common impedance problems occur in guitar and amp setups ?

Thanks  Paul

[octafish]

I use this buffer with piezos quite a bit, either to replace highs, when I percieve a loss, or to drive a pedal that is being uppity. It won't make a difference to the quality of the sound, piezos never sound as good as a properly miked instrument, and the sctatchyness usually comes from handling noise. A case in point:
A friend was impressed with my electric ukelele and asked me to install a piezo in his old classical guitar. The guitar in question being a cheapie I agreed. So I did it, built him a buffer, and told him to give me a call if anything went wrong. A week later he called me and said his guitar was clicking intermitently, but only when playing chords. I went and visited with my hot glue gun and soldering iron because I thought the shielded cable must have come loose or he had a bad solder. I got there and tried playing his guitar, and I just couldn't replicate the noise. Eventually I handed it back to him and said "You make it make the noise.". He started playing, and there it was, a click just as he played the chord. He had metal buttons on his shirt sleeves slightly pushed up and they were hitting the saddle as he strummed. The piezo was directly under the saddle and was picking up the impact and registering it as a harsh click. Neither of us could hear the buttons hitting but the piezo sure could.