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Author Topic: LR Baggs Piezo-Pickup preamp  (Read 23962 times)

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #30 on: October 24, 2016, 07:16:28 AM »
Hi zedonetx,

*Bridge* refers to the Piezo element usually located in the bridge of the guitar.
*Ring and Tip* is the term used to describe the 6.5mm plug/socket of the common guitar cord.
A Mono plug is called a TS (Tip Sleeve) and a Stereo plug has the extra contact ring, TRS (Tip Ring Sleeve)
It is common practice in guitar preamps to use a TRS Socket in combination with a Mono 6.5 Plug to switch on the preamp.
The Ring contact in the socket is bridged by the mono plug and connects the negative of the internal battery to the ground/common of the preamp turning on the power.

The same idea is also used in most battery powered pedals,, inserting your guitar cord completes the circuit and power stays on until you remove the plug.

As you have an *Nylon* string guitar you can't make use of the Magnetic section as they only work on steel string guitars.
That means you only need the top part of that circuit so you can delete everything after C4 (the cap after the Volume pot).
hope that helps.
Phil.

zedonetx

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Re: LR Baggs Piezo-Pickup preamp
« Reply #31 on: October 24, 2016, 08:41:41 AM »
Thank you very much for your answer. it really helped me. one more question: Ok, i will take the upper part of the circuit for my classical guitar. but can i also add a microphone to this circuit? microphone gives more natural sound. i mean the circuit can be with Mic and Piezo at the same time? i want to used both. :)

thanks in advance,

Hi zedonetx,

*Bridge* refers to the Piezo element usually located in the bridge of the guitar.
*Ring and Tip* is the term used to describe the 6.5mm plug/socket of the common guitar cord.
A Mono plug is called a TS (Tip Sleeve) and a Stereo plug has the extra contact ring, TRS (Tip Ring Sleeve)
It is common practice in guitar preamps to use a TRS Socket in combination with a Mono 6.5 Plug to switch on the preamp.
The Ring contact in the socket is bridged by the mono plug and connects the negative of the internal battery to the ground/common of the preamp turning on the power.

The same idea is also used in most battery powered pedals,, inserting your guitar cord completes the circuit and power stays on until you remove the plug.

As you have an *Nylon* string guitar you can't make use of the Magnetic section as they only work on steel string guitars.
That means you only need the top part of that circuit so you can delete everything after C4 (the cap after the Volume pot).
hope that helps.
Phil.

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #32 on: October 24, 2016, 09:05:02 AM »
As you are likely not yet fully conversant with this type of setup I don't recommend a microphone addon.
Yes it has been done but requires a special mic and some specialized knowledge.
Even the best on board mic setups can have feedback issues and still will not sound as good as a normal outboard mic.

A piezo PU is ideally suited to Nylon guitar and in my experience actually often better sound reproduction than most microphones. (outside of a pro studio setup) 8|
Phil.

zedonetx

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Re: LR Baggs Piezo-Pickup preamp
« Reply #33 on: October 25, 2016, 04:03:11 AM »
As I am very interested in that topic, I decided to make a PCB schematic with PCBwizard v3.5. I added *.pcb file now to let you see the diagram. After making sure of the drawing, i will make auto-routing and it will be ready for PCB print-out. :) As you see, i only did the piezo part of the circuit, as @Phatt said, i didnt take the magnetic part of the circuit as long as it is for my nylon string guitar :) thanks to @Phatt

Battery should be supplied with 9V, right?

Any suggestions for the schematic that I have drawn is appreciated!

As you are likely not yet fully conversant with this type of setup I don't recommend a microphone addon.
Yes it has been done but requires a special mic and some specialized knowledge.
Even the best on board mic setups can have feedback issues and still will not sound as good as a normal outboard mic.

A piezo PU is ideally suited to Nylon guitar and in my experience actually often better sound reproduction than most microphones. (outside of a pro studio setup) 8|
Phil.
« Last Edit: October 25, 2016, 07:56:59 AM by zedonetx »

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #34 on: October 25, 2016, 07:54:29 AM »
OK you score 10 for your enthusiasm :dbtu: but don't get ahead of yourself this is not as simple as it looks. :-X
Auto route is fine if you are making mother boards but this is not the same on several levels. 8|
For audio circuits like this auto route is the fastest way to make more land fill. :'( :'(

This is a very high impedance input and highly prone to picking crud noise.
Keep the input away from output.
Don't make very fine tracks and pads (I'm assuming you are going to hand etch & drill this PCB)
You are bound to end up needing to change a component and tiny tracks & pads are only good for one or two shots. There should be a global menu to set pad and track dimensions,, so use it. :tu:

I've edited your schematic to give you some idea of how to wire it up.

Hand route the PCB and try to keep the layout much like the schematic i.e. power on one side and ground plane on the other and that should work ok for a small board like this.

Note:  I changed D1 to be in series with the battery,, works either way,,, fors and against both ways.
If IRC, Diode in series puts less stress on the diode if battery is inserted wrong.
Oh the extra cap is just extra filtering and I have read it may even help the battery.

Now;
I forgot to mention,, you might want to consider an output buffer (to drive long cables better)
just a simple BJT is all that is needed. See my PhAbb Fet Boost output on previous page for how to insert that. The circuit will work without it but a buffer covers any situation.
If there is anything I've missed I'm sure others here will see any mistakes I've missed and chime in to help.
Cheers, Phil.
« Last Edit: October 27, 2016, 01:38:12 AM by phatt »

J M Fahey

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Re: LR Baggs Piezo-Pickup preamp
« Reply #35 on: October 26, 2016, 08:17:24 PM »
I´m a little worried about D1 and C9  ???

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #36 on: October 27, 2016, 01:44:04 AM »
I´m a little worried about D1 and C9  ???
That is perfectly understandable as it was a complete balls up by me :-[ :-[
Thanks for keeping an eye on me :tu:

I've now edited that schematic and corrected that mistake.
Now excuse me,,, I have to go bang my head against a wall.
and no Anzac biscuits for me today. ;)
Phil.

J M Fahey

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Re: LR Baggs Piezo-Pickup preamp
« Reply #37 on: October 27, 2016, 08:58:51 AM »
    Hey !!!!!!  Those look GOOD!!!!  :tu:
Missing them must certainly be unbearable punishment  :'(


Quote
Ingredients

    1 1/4 cups plain flour, sifted
    1 cup rolled oats
    1/2 cup caster sugar
    3/4 cup desiccated coconut
    2 tablespoons golden syrup or treacle
    150g unsalted butter, chopped
    1/2 teaspoon bicarb soda


zedonetx

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Re: LR Baggs Piezo-Pickup preamp
« Reply #38 on: October 28, 2016, 05:12:17 AM »
Thanks to j.m.fahey and phatt.

-Arrangements were made according to the warnings.
-Piezo and battery is far from each others :)
-pcb layouts were designed by me after auto routing (it must be double-checked).
-I tried to make the minimum space for the board.
-A board with 50mmx65mm sizes would fit. The rest is your ability :)

Of course, first i would like to test the circuit on a breadboard. It is important. Firstly test it :)



OK you score 10 for your enthusiasm :dbtu: but don't get ahead of yourself this is not as simple as it looks. :-X
Auto route is fine if you are making mother boards but this is not the same on several levels. 8|
For audio circuits like this auto route is the fastest way to make more land fill. :'( :'(

This is a very high impedance input and highly prone to picking crud noise.
Keep the input away from output.
Don't make very fine tracks and pads (I'm assuming you are going to hand etch & drill this PCB)
You are bound to end up needing to change a component and tiny tracks & pads are only good for one or two shots. There should be a global menu to set pad and track dimensions,, so use it. :tu:

I've edited your schematic to give you some idea of how to wire it up.

Hand route the PCB and try to keep the layout much like the schematic i.e. power on one side and ground plane on the other and that should work ok for a small board like this.

Note:  I changed D1 to be in series with the battery,, works either way,,, fors and against both ways.
If IRC, Diode in series puts less stress on the diode if battery is inserted wrong.
Oh the extra cap is just extra filtering and I have read it may even help the battery.

Now;
I forgot to mention,, you might want to consider an output buffer (to drive long cables better)
just a simple BJT is all that is needed. See my PhAbb Fet Boost output on previous page for how to insert that. The circuit will work without it but a buffer covers any situation.
If there is anything I've missed I'm sure others here will see any mistakes I've missed and chime in to help.
Cheers, Phil.

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #39 on: October 28, 2016, 08:19:46 AM »
Thanks to j.m.fahey and phatt.

Of course, first i would like to test the circuit on a breadboard. It is important. Firstly test it :)

Wise move :dbtu:
Yes I can can see a few things on the layout that don't look right but hard to tell as part numbers are hidden.

By using a breadboard you will become more familiar with what goes where and find which nodes are sensitive to noise and it will also help you fix any PCB mistakes.

The hard part is being patient and working methodically through the whole project ironing out any potential problems *Before* you commit to a PCB.
Anytime i find a circuit that looks like a good idea I go build it on the breadboard,,I've worn out 3 breadboards over a ~20 year period.

The breadboard is your saviour,, the difference between a success or more land fill.
No need to ask how I know this to be the fastest way to make a good circuit. :lmao:
Phil.

phatt

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Re: LR Baggs Piezo-Pickup preamp
« Reply #40 on: October 28, 2016, 08:25:18 AM »
    Hey !!!!!!  Those look GOOD!!!!  :tu:
Missing them must certainly be unbearable punishment  :'(


Quote
Ingredients

    1 1/4 cups plain flour, sifted
    1 cup rolled oats
    1/2 cup caster sugar
    3/4 cup desiccated coconut
    2 tablespoons golden syrup or treacle
    150g unsalted butter, chopped
    1/2 teaspoon bicarb soda


I thought you might pickup on that one ;)
I was buying the store biscuits but they have changed the recipe and now they are rock hard and lack the flavour of the real thing,, probably no treacle. :'( :'(
Phil.

 

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