Pot value for buffered piezo and 2 magnetic pickups.

[Matteo Marziali]

Hello there!
I have to install a piezo bridge pickup (with his buffer) in a bass with 2 magnetic pickups (with Volume and Blend) and an Aguilar OBP-1 preamp.
My idea is to wire the PUs in the Blend pot, then the Mag-Piezo_Blend pot, then the Volume and at the end the preamp.
The question is about pots values: can I use 250k pots for the blend and the volume pots? Or should I use some 25k pots?
Thanks

 

[ctmullins]

Before the preamp use 250kOhm or 500kOhm, as for a passive circuit.

After the preamp use 25kOhm.

 

[Wdrdb]

Before the preamp use 250kOhm or 500kOhm, as for a passive circuit.

After the preamp use 25kOhm.

Do you know how to make a piezo buffer from scratch? I ordered a couple of Bartolini buffers for mag and piezo but I would like to make them from scratch and I only know how to solder, plus I also weld, but transistors, resistors, and pot designing is above my head, though I can follow a plan

 

[ctmullins]

Do you know how to make a piezo buffer from scratch? I ordered a couple of Bartolini buffers for mag and piezo but I would like to make them from scratch and I only know how to solder, plus I also weld, but transistors, resistors, and pot designing is above my head, though I can follow a plan

Hi - no, I don't, although there are schematics online. I usually buy the Cafe Walter PZP-1.

 

[dwizum]

I've built a small mountain of DIY piezo preamps over the last few months and tried them in basses, guitars, and ukes. Piezo buffers are usually very simple circuits, there are lots of proven designs out there, and it's easy to get a good result - so it's a good "gateway drug" to analog electronics DIY for instruments. I've tried the Cafe Walter design, and Scott Helmke's mint box piezo. They both sound great. My favorite so far is the Tillman J201 buffer - it has a small parts count and sounds good in everything. I've decided to use it going forwards since it's so small and simple. I have a mostly SMT PCB layout on OSHpark that I could share if you want to go that route, or you could easily put it (or any of the others) on a perfboard. For volume pots after the buffer (but before a preamp), I've used 250k and 100k. I like the 100k a little more on the tillman design.

I've found that much of the sound quality for a piezo pickup comes from the buffer. You can use the ultra-cheap generic piezo elements sold on ebay or elsewhere and get great sound as long as you have a good buffer. Paying fifty cents for a piezo element and maybe $5 in electronics parts to build a buffer sure beats shelling out $100+ for a brand name setup.

 

[Wdrdb]

I've built a small mountain of DIY piezo preamps over the last few months and tried them in basses, guitars, and ukes. Piezo buffers are usually very simple circuits, there are lots of proven designs out there, and it's easy to get a good result - so it's a good "gateway drug" to analog electronics DIY for instruments. I've tried the Cafe Walter design, and Scott Helmke's mint box piezo. They both sound great. My favorite so far is the Tillman J201 buffer - it has a small parts count and sounds good in everything. I've decided to use it going forwards since it's so small and simple. I have a mostly SMT PCB layout on OSHpark that I could share if you want to go that route, or you could easily put it (or any of the others) on a perfboard. For volume pots after the buffer (but before a preamp), I've used 250k and 100k. I like the 100k a little more on the tillman design.

I've found that much of the sound quality for a piezo pickup comes from the buffer. You can use the ultra-cheap generic piezo elements sold on ebay or elsewhere and get great sound as long as you have a good buffer. Paying fifty cents for a piezo element and maybe $5 in electronics parts to build a buffer sure beats shelling out $100+ for a brand name
Please, would you share that design of a buffer? I really want to make them myself. You'd be completely making my day/week as I've been searching endlessly for a design.

 

[byacey]

You might want to have a look at this:
DIY Factory - country hick

 

[dwizum]

Please, would you share that design of a buffer? I really want to make them myself. You'd be completely making my day/week as I've been searching endlessly for a design.

The original design and everything you need to know to build it is at the link I posted:

Discrete FET Guitar Preamp

You could use the information there to build it yourself on perfboard or to make your own pcb.

What I did was make a PCB layout for it at OSHpark, which is a fab house that allows sharing. Here's a link to the shared pcb on OSHPark:
OSH Park ~

You can use the first link to Tillman's site to make up your bill of materials for the components if you want to build on the pcb I designed. I used the same part numbers and values so everything should line up. I used the SOT23 package for the J201 since that seems to be the only package that's reliably available any more. The resistors are all 0805 size, and the two caps are 5mm diameter with 2mm lead spacing. If you solder the caps on the bottom of the board, you can bend the leads at 90 degrees and lay them down "flat" against the board to make it more compact. Built like that it's easy to slip the whole thing in a bit of shrink tube once it's done. Then you can just velcro or double stick tape it to the inside of the instrument. Although the pcb is so small it can be held in place just fine without being stuck down if you're careful with wiring (use stiff wires without any excess length).

 

[BQFS]

The original design and everything you need to know to build it is at the link I posted:

Discrete FET Guitar Preamp

You could use the information there to build it yourself on perfboard or to make your own pcb.

What I did was make a PCB layout for it at OSHpark, which is a fab house that allows sharing. Here's a link to the shared pcb on OSHPark:
OSH Park ~

You can use the first link to Tillman's site to make up your bill of materials for the components if you want to build on the pcb I designed. I used the same part numbers and values so everything should line up. I used the SOT23 package for the J201 since that seems to be the only package that's reliably available any more. The resistors are all 0805 size, and the two caps are 5mm diameter with 2mm lead spacing. If you solder the caps on the bottom of the board, you can bend the leads at 90 degrees and lay them down "flat" against the board to make it more compact. Built like that it's easy to slip the whole thing in a bit of shrink tube once it's done. Then you can just velcro or double stick tape it to the inside of the instrument. Although the pcb is so small it can be held in place just fine without being stuck down if you're careful with wiring (use stiff wires without any excess length).

Thank you very much. This is GREAT information. I have already gone and ordered a half-dozen boards from OSH, whom I regularly use to produce my other boards, and ordered the rest of the parts from Mouser. I figure I will use one or two myself, and put the others up for sale as there will probably be others interested. It's sure not expensive compared to the commercial board, that's for sure.