Awesome concise video. I'm making electric guitars with a piezo disc in neck pocket with normal bridge pickup. This was exactly what I was looking for, will be using with 9 volt battery and making it internal. Thanks man!
wow... Good eyes! I literally do not know lol. Any guesses? I do remember that I actually built this twice and edited the footage into one video because I had short circuit issues on the first 'prototype'.
I'm new to electronics and have no clue where to buy these parts. I'm having trouble finding the audio jack like yours! I'm trying to build one of these preamps for a contact microphone for my field recorder.
They were a lucky find for me! The challenge is finding them for sale in small quantities with reasonable shipping. You can try searching for DPDT Audio Jack, because this is an Audio Jack with a DPDT switch built in. The 1/4" jack itself also goes by many other names such as Phone Jack, 6.35mm jack, P38 connector and so on.
Thank you very much for your video. It was a very easy circuit, but had a problem with the volume. I am using a DIY cigar box amp (LM386). I started to add a trim pod on the output but instead made a voltage divider from two 2K Ohm resistors. It is much better.
Hi, I built this recently, and it’s awesome! Quick issue though, it’s waaay too loud. How would I go about reducing the output/lower gain? I’m using a Tune-o-matic style piezo bridge, and a 9v battery, and running the output of the preamp into a passive 25 k ohm volume potentiometer (my guitar already had that installed). That is of course why it’s loud. It sounded great, so I know it works well with the current bridge, battery and volume control setup, but I need to have the (logarithmic) potentiometer at around 3/10 to match the loudness of the magnetic pickups in the guitar (which I know work fine by comparing to other guitars). Any recommendations? I tried soldering a 500k pot as the “gain resistor”, but still too loud, and would that mess with the bias resistor as they become closer in value? (I’m new to this stuff😅) I’ve also checked that all my components can handle the 9v battery To be perfectly clear, this is a great design and works just as intended, I’m just using it for something else😂 It would work great for a disc piezo with a 3.3v battery I think
Hey, thanks for watching and commenting! I think your intuition about the bias being affected if the resistors values change is essentially accurate. To reduce gain, you can put a resistor between the FET source terminal and ground. Try 1k?
@@Psychotenuse Thanks for responding! I thought about that, as that is would effectively halv the voltage (or at least power output), but do you know if that would significantly reduce the battery life? I would assume it would be halved. As long as it doesn’t reduce it by more than half it would be fine, as it’s only a secondary function in my guitar, and the switch to engage the piezo system is directly turning the preamp on or off
@@Psychotenuse Sorry, thought you meant adding a resistor to ground where the battery first connected to the circuit to divide the input voltage (again, I’m new to this stuff, and misheard which side of the transistor you were referring to). I tried what you suggested, and it worked! I think 1k was too much, but I think around 500ohm is perfect. Again, thank you so much for both the help and the video, this is the best video explaining this I have been able to find on the internet!
Hello; Thanks for the video. I want to ask you some questions so that I can be clear and carry out the project. 1. By placing a 10Mega ohm resistor, convert the input of the Preamp, in a Preamp that accepts up to a Piezo with a very high impedance of 10Mega ohms? , 2- Why use a 3.3v Bat, if you could modify the circuit to be able to use an AC Power Supply of about 5V? , 3- Can I use a 9V AC Pw Sup. guitar pedal? 4- Instead of using the cable with the 1/4 male connector, can I use a 1/4 female input connector? I am looking to buy a Preamp with inputs capable of accepting Piezos up to 10Meg ohms, but they are very expensive. I wait for your answers. (Greetings from Puerto Rico Caribbean Sea).
Hi. Thanks for watching :) 1. Perhaps something is being lost in translation. I don't understand the question. 2. and 3. Using batteries is better for noise etc. 4. Yes, of course.
@@Psychotenuse Thanks for the answers. I will ask you question #1 in another way: What is the maximum impedance or resistance of the input of the Preamp?
So the input capacitance of the 2n7000 MOSFET is listed as 60pF in it's datasheet. This means (unless I messed up :P ) that the input impedance of the FET itself varies between 132k at 20kHz to 132M at 20Hz. Luckily, piezo transducers are capacitive sources, so if your piezo capacitance is on the same order of magnitude as your FET input capacitance (which it would be if the 10M figure were calculated at ~1kHz), then you'll get some attenuation but won't get terrible filtering. Ideally, your biasing resistor would be in the giga ohm range, but the problem with such large resistors is that they can be noisy. You would need a special expensive resistor that is not noisy. (Expensive as in a couple of dollars maybe).
2 things: 1. Thank you for this excellent video, listening with headphones there was a stark contrast between no preamp and preamp. So much less noise and much improved low end. 2. I have studied your video and schematic many times as a way to learn audio electronics (I am slow to learn this stuff) and I think I understand but I am unsure why there is a capacitor between the input signal and the MOSFET. Capacitors smooth out the supply of current, isn't that the opposite of what you want with the audio signal? Am I misunderstanding the signal flow?
It is what is called 'capacitive coupling', which does what is often described as blocking DC. It is not strictly necessary here since the FET and the piezo are both capacitive anyway, but it allows for more consistent performance.
@@Psychotenuse I guess my question is actually this: how does having a cap between the signal and the gate terminal not ruin the signal by smoothing it out?
@@Psychotenuse I'm thinking in terms of fluid dynamics, as in the piezo would be an unsteady stream flowing into a bucket (the cap) which in turn releases a steady stream. This seems like it would cause the fluctuations of current to "smooth out" and thus no longer accurately represent the sound waves applied to the piezo. I suppose that's not an apt comparison?
Your project makes me wonder.. Where should I add a pot for a tone dial. I have transducers under my saddle (without preamp) and they work fine but I could benefit from a stronger signal and maibe a tone pot.. Thanks!
Congratulations, I like the way it sounds. Would you please make a list of elements used and a drawing of circuit, I cannot see it clear, and find your preamp fantastic, thank you
Thank you for the video. If I would replace the 10M resistor with a pot (to make input impedance sweepable from 5 to 15 M), I would mess with the Mosfet's biasing, right? Is there an easy way to convert tge circuit to source follower to keep the output impedance low?
You wouldn't mess with the biasing too much, but the pot might be noisier than a fixed resistor. You don't get any voltage gain with a follower circuit, so I'm not sure if that's what you want. The output impedance of this circuit should be low enough for most purposes other than actually driving speakers or headphones. And you wouldn't normally use a follower to drive headphones either.
I made this but i have a problem. It worked fine untill a moment. Now there is a constant loud BUZZ. I don't have it connected to mains voltage in any way. I changed the transistor with no succes. Do you know what i did wrong? I just can't find the problem that suddenly came. I had got a message on my laptop that the USB port was pulling more current than the power supply could handle. But it was just for once after the problem came.
Why your laptop? Why the USB port? I don't understand how you have things hooked up. Anyway, If it was working fine and then stopped, that can only mean that something went wrong with the circuit. My guess is either a short circuit (something is touching that shouldn't be) or a loose connection (something isn't touching that should be). Maybe the wire connecting your circuit to the metal case has come undone.
Another possibility is that there is a noise source that suddenly activated somewhere nearby, that could be any electrical device in the vicinity including your laptop. This is less likely, though. First, check your connections and make sure ground is connected to the case.
@@Psychotenuse i use the USB port of my laptop as the powersupply. All grounds are connected to eachother. I have tested it with a multimeter. The last thing i could think of is that something is wrong with the 10M ohm resistor. I only had 1M so i solderd 10 in series. But i cant test the full resistance since the meter only goes upto 2M. I Will remove the resistor and check if all the resistors still are 1m.
Thank you so much for your tutorial. You mentioned the 1k resistance sets the output impedance. What would the approx. impedance of this preamp with that 1k resistance? and if I want to reduce the impedance should I use a lower resistance value? Thank you!!!
1k is the output resistance with a 1k resistor; the drain of the mosfet is essentially a current source here. Technically the 1M appears in parallel but you can obviously ignore that. I wouldn't recommend going much lower than 1k because you'll start loading the battery too much. If you double the drain resistor you get double the output impedance and double (+6db) the gain.
@@Psychotenuse oh I see now! Thank you so much!! You do the 10M resistor at the input because the impedance of the piezo is around 1 to 8M right?? Is just that I want to match the piezo with a magnetic pickup which is 7.5k. I'm guessing now 1k will be good but can I experiment with a 5k and 7k just to see what sound? better?
@@oscarfernandoofpublicnature 7.5k is probably the DC resistance of your pickup. For a passive pickup the overall impedance is usually mostly inductive. 50k maybe. 10k might be typical for active pickups. 7k drain resistor in the circuit from this video means a lot of gain; maybe you can put 10k and add a 1k source resistor to bring the gain back down.
@@Psychotenuse thank you again. My problem is I forgot all my electricity lessons from college haha. Ill study but definetly follow you guidance here so I don't have to bother you anymore!! Thanks for the help!! Cheers
I made this preamp.l tried this preamp with my givson venus rosewood guitar and 2030ic amplifier. But it did not work!😢😢😡😡😡😡😡😡😡😡 I have a pickup in my guitar
I did everything like your job I just used 10nf instead 104nf capacitor at the input and 100uf instead 10v 470uf capacitor to the output. I would especially benifit if you would do this.😢😢😢😢😢😢😢
Hi, i just done the circuit but i have a ground problem, i revised every thing but i can't find the problem, i'm using a nylon guitar that i put a piezo under bridge. The problem solves when i touch the cable with My hand, thank For the circuit!!!!
if i would like to add a potentiometer to control the volume, which of the resistors you would replace? or add in a different place? thnks for the great video!
You could just add a potentiometer on the output, i.e. between the drain of the FET and ground, with the output capacitor connected to the middle of the potentiometer instead of directly to the drain of the FET. You could also add a variable resistor between the source of the FET and ground, to reduce the gain, or in series with the drain resistor, to increase the gain.
@@Psychotenuse Hey! Nice project, thank you! What pot would you suggest? I intend to use 2x3V batteries. Also, as I understand it, I should connect the one end of the pot to the drain of the FET, the middle to the capacitor and the other to the ground. Is this right?
Hello, I am looking for help!! I want to combine a piezo with a humbucker pickup. Should I just sum the output of your circuit with the output of the humbucker at the jack? And should I modify something on your circuit to do so? ...or should I sum the humbucker and piezo together before the input of your circuit?? Thank you for any guidance and please keep making your vids!
@@Psychotenuse thank you for replying!! I've been looking and I've seen people put resistors in each hot wires of the pickups and then those go togueter to the input of a circuit or tip of the jack, like a "Y". Is that good?
@@kathemera You would have to match the signal levels and impedances to get a decent mix. You can add an output level control to the preamp circuit by replacing R1 with a trim pot and connecting the positive end of the output capacitor to the middle leg of the pot instead of the drain of the mosfet. You could then adjust the pot to have more or less piezo in your sound. Since the output impedance of your humbucker is probably 50k-ish, you can use a 50k resistor on the piezo-preamp branch of your "Y" and omit the resistor (i.e. zero ohms) on the humbucker branch.
Does this result in a DC offset - or how are negative frequencies handled in this circuit ? I always thought audio is an AC signal. I built it - sounds awesome - it even is too loud for my line input. Can one of the components be modified in order to get less output - Eg replacing R1 - the 1K Resistor with 1200 Ohm? Thanks for this great lesson in circuit design.
The input and output capacitors are there to block DC; that's the way engineers think about it. You can reduce the gain by making R1 smaller, but that will also reduce battery life. A more standard way to do it would be to add a resistor (100 ohms or less maybe) between the source of the mosfet and ground.
Do you have some guidance on reducing noise ? - Using a battery - Use short cables - Ground everything - Twist input cable (add some kind of shielding?) - Put components from input source until signal amplification into metal encasing (do you know how thick it should be? or what kind of metal is working best?) Are there more or less noisy piezos? I`m not able to get a really clean signal as you achieved here yet. Anything important I forgot ?
@@xpeace77 Make sure your metal casing is grounded. If you're having problems with noise, your first step should be to try and figure out where the noise is coming from and what is causing it. First, check whether the noise is coming from the guitar itself or from the preamp. If the noise stops when you unplug the preamp from the guitar, then you know the noise is coming from the guitar. Next, what kind of noise do you have? Humming is due to magnetic fields and can be addressed by using twisted pair cables. Static or hissing is usually due to electric fields and can be addressed by shielding the circuit. Crackling or popping sounds are typically due to loose connections. Components also have intrinsic thermal noise, but that shouldn't be a problem for moderate-gain circuits like this one.
Cool circuit :) I've seen the input impedance set with a 2m resistor in other piezo disc pre-amps,(LR Baggs HiFi), they say it makes it a bit brighter. Would altering your circuit with a 2m input impedance resistor work OK or would other components need to be changed?
2M should be fine. It would be a little brighter in theory, but it also might be slightly noisier. On the whole though I doubt it would make an audible difference.
@@Psychotenuse Thank-you for the reply and the video. One more question, could a volume/tone be added to the piezo element before the pre-amp(on-board the guitar) and if so what value pots would you suggest?
So I want to use this as a stage before an active preamp, will the 9V(from the true preamp) power this as well? Or do I need to battery in this circuit as well? How would you address that?
Um... no. This circuit has a capacitor in line with the output, so it can't be powered by the signal sink. Even if you removed that capacitor it would depend entirely on the nature of your "true preamp" and I doubt any guitar preamps are designed to send power down the input line; that tends to be something you only do if you're expecting someone to plug in an electret mic.
@@Psychotenuse so I’m not sure I understand. All this electrical and signal stuff if relatively new to me, so thanks for your time and please bear with me…I building an semi hollow guitar. Like a telecaster the I already own, I want it to have a piezo bridge. The telecaster has a fishman piezo bridge, with a 9V powered preamp. Not understanding the issues with piezos, magnetic pickups, and differing impedance, I bought a neovin pre-1 guitar preamp. I was thinking I could use this to improve the piezo signal quality in much the same way that the fishman does on my telecaster. It wasn’t until I really started reading about piezo pickups/bridges did I begin to understand the difference with piezo impedance and magnetic pickup impedance. So, now being unsure if the preamp I bought is suitable to condition the signal from this piezo bridge, I found your channel and actually made your circuit(haven’t tested it yet but it should work fine). I intend to run my signal from the bridge into it, then send that signal to my “true”(or previously purchased) preamp, which is powered by a 9V battery. You are saying that this circuit won’t function if I make it the first stage in the preamp powered by 9V?
@@Psychotenuse the objective is to condition the piezo bridge’s signal. Maybe the 9V preamp will do that. I just don’t know very much about impedance, especially when the other pickups are magnetic
@@darrellgreen3592 My point was simply that you will need a battery for the circuit. Given what you're tring to do I would recommend trying out the piezo wired directly to the preamp you puchased. Worst case, it will sound a bit tinny; you're not going to damage anything. The main concern with using both circuits together is that you might get unwanted saturation.
@@darrellgreen3592 There's three types of impedance: Inductive, capacitive and resistive. Inductive and capacitive are like opposites of each other, resistive is neutral. Magnetic pickups have mostly inductive impedance and a bit of resistive, meaning that they naturally lose high frequencies and using a buffer (conditioning the signal as you say) helps preserve the high frequencies. Piezos have mostly capacitive impedance, meaning that they naturally lose low frequencies and buffering helps preserve the low end.
Yes, probably, particularly if I built the circuit into the mic with short wires on the low level side. Unfortunately that mic only existed for a short period of time after the video was made :P
@@Psychotenuse awh, I guess I'll just have to replicate it to truly find out :D Just to clarify, what do you mean by the "low level side"? Is that the short end of the tube?
This straightforward design is exactly what I am looking for for my project, which is a bass uke with rubber/latex strings and a piezo disc transducer. How do you think it will sound on the lower 400-4k frequencies? should I change any of the parts values? I plan to use a rechargeable CR123a in place of the coin cell, any issues you can see with that? Thanks for the great content!
The RC rolloffs on this are well below 20Hz, so there should not be a problem at low frequencies specifically. I see no reason that the rechargeable battery would be problem either, as long as the charging is done by removing the battery from the device and putting it into an off-the-shelf li-ion battery charger. If you want to make the device plug-in rechargeable you would have to include li-on charging circuitry.
@@Psychotenuse Thanks! Other comments have asked about adding a pot to provide gain control but I really appreciate the simple fixed-gain setup in my application since I am installing it inside the instrument and don't want to make holes for knobs. As you suggest I will use a battery holder for the CR123 and remove the battery to charge it. Have been watching some of your other videos and there are some very cool projects. Love the channel!
@@Psychotenuse use a 100kΩ or a 1MΩ resistor in parallel in input capacitor like a CR filter and in output use a 100 nF and one 10μF capacitor up to 50μF
Hey nice video... I have a dought though... I made a magnetic pickup my own and using it as the pickup for my guitar... It works fine but has less gain.. So if i make this circuit will it be ok with the magnetic pickup? Like will there be any noise or over gain?... Also how long will i get the battery life of 3.3v.. Just to make sure will i be needing a power..switch Thank You
does it have to be electrolitic caps? Wouldn't it be easier to use non polarised film or box caps? Also in the voice over you say a 10nf cap and a 100uf cap. However the schematic says 100nf and 100uf? Nice preamp, surprisingly clear and decent quality considering cost of parts. thanks for the vid.
I did actually use a 10nF capacitor on the input, thanks for pointing that out! I will fix the number in the schematic. The output capacitor is electrolytic simply because unpolarized capacitors with such high capacitance values are generally too big and expensive.
Hm. I don't know, but many hours, probably. Let's see. So the battery is discharging through an effective load of about of 1k ohm (order of magnitude). The voltage is 3V so the current is about 3mA. Divide the (according to google) 200mAh capacity of one of these cells by this current value, and we get 66 hours. Not sure how accurate that is, but it's a first approximation, I guess.
@@Psychotenuse cool thank you ever so much. Last device I built was tube and on a mains powered power supply so I didn’t have to worry about battery power. If you can find time. Build yourself a valvecaster. I built one as a valve preamp paired with a solid state poweramp similar to the valvestate amps of the 90s. Sounds half decent. Easy enough and I’m sure you could do one very well! Try it
Hey mate, this is exactly what i need. Just one question: Can this circuit run fine on 5v, or do you need different components or capacitors for that? I want to power this using a 5v power bank of phone. Will it work? Thank you for all the amazing projects you have done.
@@Psychotenuse ok I found it. For some reason on the mobile application it is not listed and there is no option for it. I'll reach out to you shortly. Thanks
Well done video and great sound demo! And I love "I'll connect a black wire here to remind me that it goes to ground." Nice trick.
Glad you liked it! Thanks for watching :)
Awesome concise video. I'm making electric guitars with a piezo disc in neck pocket with normal bridge pickup. This was exactly what I was looking for, will be using with 9 volt battery and making it internal. Thanks man!
Glad to be of help! Thanks for watching :)
good day, I'm curious how that piezo pickup is sounding on the guitars, do you have some videos on it?
nice typical circuit design but pay attention to the soldering as you have some cold soldering and may cause some humming issues
2:25 you can see a cap on the signal wire... why no mention of it?
wow... Good eyes! I literally do not know lol. Any guesses?
I do remember that I actually built this twice and edited the footage into one video because I had short circuit issues on the first 'prototype'.
I'm new to electronics and have no clue where to buy these parts. I'm having trouble finding the audio jack like yours! I'm trying to build one of these preamps for a contact microphone for my field recorder.
They were a lucky find for me! The challenge is finding them for sale in small quantities with reasonable shipping.
You can try searching for DPDT Audio Jack, because this is an Audio Jack with a DPDT switch built in. The 1/4" jack itself also goes by many other names such as Phone Jack, 6.35mm jack, P38 connector and so on.
Thank you very much for your video. It was a very easy circuit, but had a problem with the volume. I am using a DIY cigar box amp (LM386). I started to add a trim pod on the output but instead made a voltage divider from two 2K Ohm resistors. It is much better.
Glad to hear it worked out for you :)
Why are you painting the solder joints with lead instead of soldering? Regards..
I like to use the tin and reflow method when possible. Strong solder joints and minimal mess.
This is exactly what I was thinking about yesterday! I need one!!
Nice! Hope you build it :)
Hi, I built this recently, and it’s awesome! Quick issue though, it’s waaay too loud. How would I go about reducing the output/lower gain? I’m using a Tune-o-matic style piezo bridge, and a 9v battery, and running the output of the preamp into a passive 25 k ohm volume potentiometer (my guitar already had that installed). That is of course why it’s loud. It sounded great, so I know it works well with the current bridge, battery and volume control setup, but I need to have the (logarithmic) potentiometer at around 3/10 to match the loudness of the magnetic pickups in the guitar (which I know work fine by comparing to other guitars). Any recommendations? I tried soldering a 500k pot as the “gain resistor”, but still too loud, and would that mess with the bias resistor as they become closer in value? (I’m new to this stuff😅) I’ve also checked that all my components can handle the 9v battery
To be perfectly clear, this is a great design and works just as intended, I’m just using it for something else😂 It would work great for a disc piezo with a 3.3v battery I think
Hey, thanks for watching and commenting! I think your intuition about the bias being affected if the resistors values change is essentially accurate.
To reduce gain, you can put a resistor between the FET source terminal and ground. Try 1k?
@@Psychotenuse Thanks for responding! I thought about that, as that is would effectively halv the voltage (or at least power output), but do you know if that would significantly reduce the battery life? I would assume it would be halved. As long as it doesn’t reduce it by more than half it would be fine, as it’s only a secondary function in my guitar, and the switch to engage the piezo system is directly turning the preamp on or off
@Thecoolman1 the battery life should go up with the addition of the source resistor
@@Psychotenuse Sorry, thought you meant adding a resistor to ground where the battery first connected to the circuit to divide the input voltage (again, I’m new to this stuff, and misheard which side of the transistor you were referring to). I tried what you suggested, and it worked! I think 1k was too much, but I think around 500ohm is perfect. Again, thank you so much for both the help and the video, this is the best video explaining this I have been able to find on the internet!
That would work too, actually.
Hello;
Thanks for the video. I want to ask you some questions so that I can be clear and carry out the project.
1. By placing a 10Mega ohm resistor, convert the input of the Preamp, in a Preamp that accepts up to a Piezo with a very high impedance of 10Mega ohms? ,
2- Why use a 3.3v Bat, if you could modify the circuit to be able to use an AC Power Supply of about 5V? ,
3- Can I use a 9V AC Pw Sup. guitar pedal?
4- Instead of using the cable with the 1/4 male connector, can I use a 1/4 female input connector?
I am looking to buy a Preamp with inputs capable of accepting Piezos up to 10Meg ohms, but they are very expensive.
I wait for your answers. (Greetings from Puerto Rico Caribbean Sea).
Hi. Thanks for watching :)
1. Perhaps something is being lost in translation. I don't understand the question.
2. and 3. Using batteries is better for noise etc.
4. Yes, of course.
@@Psychotenuse
Thanks for the answers. I will ask you question #1 in another way: What is the maximum impedance or resistance of the input of the Preamp?
So the input capacitance of the 2n7000 MOSFET is listed as 60pF in it's datasheet. This means (unless I messed up :P ) that the input impedance of the FET itself varies between 132k at 20kHz to 132M at 20Hz.
Luckily, piezo transducers are capacitive sources, so if your piezo capacitance is on the same order of magnitude as your FET input capacitance (which it would be if the 10M figure were calculated at ~1kHz), then you'll get some attenuation but won't get terrible filtering. Ideally, your biasing resistor would be in the giga ohm range, but the problem with such large resistors is that they can be noisy. You would need a special expensive resistor that is not noisy. (Expensive as in a couple of dollars maybe).
2 things: 1. Thank you for this excellent video, listening with headphones there was a stark contrast between no preamp and preamp. So much less noise and much improved low end. 2. I have studied your video and schematic many times as a way to learn audio electronics (I am slow to learn this stuff) and I think I understand but I am unsure why there is a capacitor between the input signal and the MOSFET. Capacitors smooth out the supply of current, isn't that the opposite of what you want with the audio signal? Am I misunderstanding the signal flow?
It is what is called 'capacitive coupling', which does what is often described as blocking DC. It is not strictly necessary here since the FET and the piezo are both capacitive anyway, but it allows for more consistent performance.
@@Psychotenuse I guess my question is actually this: how does having a cap between the signal and the gate terminal not ruin the signal by smoothing it out?
It wouldn't 'smooth it out', the opposite really as high pass
@@Psychotenuse I'm thinking in terms of fluid dynamics, as in the piezo would be an unsteady stream flowing into a bucket (the cap) which in turn releases a steady stream.
This seems like it would cause the fluctuations of current to "smooth out" and thus no longer accurately represent the sound waves applied to the piezo. I suppose that's not an apt comparison?
@@Psychotenuse my apologies for taking your time, I have certainly subbed and liked
Cool !!! Need to try this on my guitar
Nice :)
Keep in mind this will only be useful if your guitar doesn't already have a built-in preamp.
What would I have to change if I want to use a 9V battery instead of the battery you used here ?
Nothing, really.
maybe capacitors
Your project makes me wonder.. Where should I add a pot for a tone dial. I have transducers under my saddle (without preamp) and they work fine but I could benefit from a stronger signal and maibe a tone pot.. Thanks!
Tone knob... you could put a 100pF capacitor and a 10k resistor in series, across the output maybe.
@@Psychotenuse like a treble bleed circuit.. thanks!
How many dB are obtained with this scheme ? I am interested in over 58 dB ! What do you recommend ? Thank you very much .
I was looking for a gain of about 10 with high input impedance. For high gain, it is easiest to use an op amp.
Congratulations, I like the way it sounds. Would you please make a list of elements used and a drawing of circuit, I cannot see it clear, and find your preamp fantastic, thank you
Thanks :)
There's a schematic linked in the description.
Thank you...I am trying to get through the link..
Thank you for the video. If I would replace the 10M resistor with a pot (to make input impedance sweepable from 5 to 15 M), I would mess with the Mosfet's biasing, right?
Is there an easy way to convert tge circuit to source follower to keep the output impedance low?
You wouldn't mess with the biasing too much, but the pot might be noisier than a fixed resistor.
You don't get any voltage gain with a follower circuit, so I'm not sure if that's what you want. The output impedance of this circuit should be low enough for most purposes other than actually driving speakers or headphones. And you wouldn't normally use a follower to drive headphones either.
dont see why you would do either of those
Hello... Is it possible to use a 9v battery? Connecting a resistor in series?
You wouldn't need to, you can use it as is. You'd just get a lot of gain.
@@Psychotenuse oh.. Okay thanks
I made this but i have a problem.
It worked fine untill a moment. Now there is a constant loud BUZZ. I don't have it connected to mains voltage in any way. I changed the transistor with no succes.
Do you know what i did wrong? I just can't find the problem that suddenly came. I had got a message on my laptop that the USB port was pulling more current than the power supply could handle. But it was just for once after the problem came.
Why your laptop? Why the USB port? I don't understand how you have things hooked up.
Anyway, If it was working fine and then stopped, that can only mean that something went wrong with the circuit. My guess is either a short circuit (something is touching that shouldn't be) or a loose connection (something isn't touching that should be).
Maybe the wire connecting your circuit to the metal case has come undone.
Another possibility is that there is a noise source that suddenly activated somewhere nearby, that could be any electrical device in the vicinity including your laptop.
This is less likely, though. First, check your connections and make sure ground is connected to the case.
@@Psychotenuse i use the USB port of my laptop as the powersupply.
All grounds are connected to eachother. I have tested it with a multimeter. The last thing i could think of is that something is wrong with the 10M ohm resistor. I only had 1M so i solderd 10 in series. But i cant test the full resistance since the meter only goes upto 2M. I Will remove the resistor and check if all the resistors still are 1m.
@@TheDutchFighters I would advise that you use a battery. Fewer unknowns.
Hi, is there a way you could power this circuit with the 48v Phantom power of a mixer?
It could definitely be done.
@@Psychotenuse you think it would be necessary to reduce the voltage with a zener or do you think it should work without adding any component
@@pauencinaslaffitte5256 It's a self-biasing circuit, so I think it should be fine as is. The output signal will be very strong though!
Hey man, I am absolutely noob to these things. Can you please suggest any alternatives for the MOSFET?
The bs170 if I'm not mistaken and the 2n7000 are the only two popular n-channel signal fets for hobby electronics. Either should work here, I think.
Thank you so much for your tutorial. You mentioned the 1k resistance sets the output impedance. What would the approx. impedance of this preamp with that 1k resistance? and if I want to reduce the impedance should I use a lower resistance value? Thank you!!!
1k is the output resistance with a 1k resistor; the drain of the mosfet is essentially a current source here. Technically the 1M appears in parallel but you can obviously ignore that. I wouldn't recommend going much lower than 1k because you'll start loading the battery too much. If you double the drain resistor you get double the output impedance and double (+6db) the gain.
@@Psychotenuse oh I see now! Thank you so much!! You do the 10M resistor at the input because the impedance of the piezo is around 1 to 8M right?? Is just that I want to match the piezo with a magnetic pickup which is 7.5k. I'm guessing now 1k will be good but can I experiment with a 5k and 7k just to see what sound? better?
@@oscarfernandoofpublicnature 7.5k is probably the DC resistance of your pickup. For a passive pickup the overall impedance is usually mostly inductive. 50k maybe. 10k might be typical for active pickups.
7k drain resistor in the circuit from this video means a lot of gain; maybe you can put 10k and add a 1k source resistor to bring the gain back down.
@@Psychotenuse thank you again. My problem is I forgot all my electricity lessons from college haha. Ill study but definetly follow you guidance here so I don't have to bother you anymore!! Thanks for the help!! Cheers
@@oscarfernandoofpublicnature No worries, glad to help! Pretty normal to forget most things from school lol.
Great clear instructions! Any reason not to make this a pedal instead?
Yeah, cable length and ground isolation
I made this preamp.l tried this preamp with my givson venus rosewood guitar and 2030ic amplifier. But it did not work!😢😢😡😡😡😡😡😡😡😡 I have a pickup in my guitar
That's unfortunate :(
Most often, the issue is some kind of wrong connection
I use 10v 470 uf capacitor to the output and 104j nonpolar capacitor to input but this did not work
Does this circuit works on pickup with acoustic guitar? Please tell me!
Give a solution to it!😢😢😢😢
I'd have to see what you've done and how it's different
I did everything like your job I just used 10nf instead 104nf capacitor at the input and 100uf instead 10v 470uf capacitor to the output. I would especially benifit if you would do this.😢😢😢😢😢😢😢
Hi!
Could you clarify?
Yes!
Can you make a acoustic guitar amplifier with lm386 ic
Hi, i just done the circuit but i have a ground problem, i revised every thing but i can't find the problem, i'm using a nylon guitar that i put a piezo under bridge. The problem solves when i touch the cable with My hand, thank For the circuit!!!!
Where are you touching the cable and what are you plugging it into?
@@Psychotenuse thanks for your answer, the problem was the piezo 😁😁😁😁
Nice job there would this preamp work for an acoustic bass guitar with piezo?
Yeah, it should. The low frequency rolloffs are certainly low enough
if i would like to add a potentiometer to control the volume, which of the resistors you would replace? or add in a different place?
thnks for the great video!
You could just add a potentiometer on the output, i.e. between the drain of the FET and ground, with the output capacitor connected to the middle of the potentiometer instead of directly to the drain of the FET.
You could also add a variable resistor between the source of the FET and ground, to reduce the gain, or in series with the drain resistor, to increase the gain.
@@Psychotenuse Hey! Nice project, thank you! What pot would you suggest? I intend to use 2x3V batteries. Also, as I understand it, I should connect the one end of the pot to the drain of the FET, the middle to the capacitor and the other to the ground. Is this right?
@koritis1 yeah
@@Psychotenuse Thank you for your answer! A 250 pot will do the job or it doesn't matter what kind of pot I'll use?
Hello, I am looking for help!! I want to combine a piezo with a humbucker pickup. Should I just sum the output of your circuit with the output of the humbucker at the jack? And should I modify something on your circuit to do so? ...or should I sum the humbucker and piezo together before the input of your circuit?? Thank you for any guidance and please keep making your vids!
How do you plan to do the summing?
@@Psychotenuse thank you for replying!! I've been looking and I've seen people put resistors in each hot wires of the pickups and then those go togueter to the input of a circuit or tip of the jack, like a "Y". Is that good?
@@kathemera You would have to match the signal levels and impedances to get a decent mix.
You can add an output level control to the preamp circuit by replacing R1 with a trim pot and connecting the positive end of the output capacitor to the middle leg of the pot instead of the drain of the mosfet. You could then adjust the pot to have more or less piezo in your sound.
Since the output impedance of your humbucker is probably 50k-ish, you can use a 50k resistor on the piezo-preamp branch of your "Y" and omit the resistor (i.e. zero ohms) on the humbucker branch.
@@Psychotenuse this is gold!! Will do exactly that!! Thank you so much!!
Does this result in a DC offset - or how are negative frequencies handled in this circuit ? I always thought audio is an AC signal. I built it - sounds awesome - it even is too loud for my line input.
Can one of the components be modified in order to get less output - Eg replacing R1 - the 1K Resistor with 1200 Ohm?
Thanks for this great lesson in circuit design.
The input and output capacitors are there to block DC; that's the way engineers think about it.
You can reduce the gain by making R1 smaller, but that will also reduce battery life. A more standard way to do it would be to add a resistor (100 ohms or less maybe) between the source of the mosfet and ground.
Do you have some guidance on reducing noise ?
- Using a battery
- Use short cables
- Ground everything
- Twist input cable (add some kind of shielding?)
- Put components from input source until signal amplification into metal encasing (do you know how thick it should be? or what kind of metal is working best?)
Are there more or less noisy piezos? I`m not able to get a really clean signal as you achieved here yet. Anything important I forgot ?
@@xpeace77 Make sure your metal casing is grounded.
If you're having problems with noise, your first step should be to try and figure out where the noise is coming from and what is causing it. First, check whether the noise is coming from the guitar itself or from the preamp. If the noise stops when you unplug the preamp from the guitar, then you know the noise is coming from the guitar.
Next, what kind of noise do you have? Humming is due to magnetic fields and can be addressed by using twisted pair cables. Static or hissing is usually due to electric fields and can be addressed by shielding the circuit. Crackling or popping sounds are typically due to loose connections. Components also have intrinsic thermal noise, but that shouldn't be a problem for moderate-gain circuits like this one.
Cool circuit :) I've seen the input impedance set with a 2m resistor in other piezo disc pre-amps,(LR Baggs HiFi), they say it makes it a bit brighter. Would altering your circuit with a 2m input impedance resistor work OK or would other components need to be changed?
2M should be fine. It would be a little brighter in theory, but it also might be slightly noisier. On the whole though I doubt it would make an audible difference.
@@Psychotenuse Thank-you for the reply and the video. One more question, could a volume/tone be added to the piezo element before the pre-amp(on-board the guitar) and if so what value pots would you suggest?
I wouldn't recommend it.
metal film resistors have less noise
So I want to use this as a stage before an active preamp, will the 9V(from the true preamp) power this as well? Or do I need to battery in this circuit as well? How would you address that?
Um... no. This circuit has a capacitor in line with the output, so it can't be powered by the signal sink. Even if you removed that capacitor it would depend entirely on the nature of your "true preamp" and I doubt any guitar preamps are designed to send power down the input line; that tends to be something you only do if you're expecting someone to plug in an electret mic.
@@Psychotenuse so I’m not sure I understand. All this electrical and signal stuff if relatively new to me, so thanks for your time and please bear with me…I building an semi hollow guitar. Like a telecaster the I already own, I want it to have a piezo bridge. The telecaster has a fishman piezo bridge, with a 9V powered preamp. Not understanding the issues with piezos, magnetic pickups, and differing impedance, I bought a neovin pre-1 guitar preamp. I was thinking I could use this to improve the piezo signal quality in much the same way that the fishman does on my telecaster. It wasn’t until I really started reading about piezo pickups/bridges did I begin to understand the difference with piezo impedance and magnetic pickup impedance. So, now being unsure if the preamp I bought is suitable to condition the signal from this piezo bridge, I found your channel and actually made your circuit(haven’t tested it yet but it should work fine). I intend to run my signal from the bridge into it, then send that signal to my “true”(or previously purchased) preamp, which is powered by a 9V battery. You are saying that this circuit won’t function if I make it the first stage in the preamp powered by 9V?
@@Psychotenuse the objective is to condition the piezo bridge’s signal. Maybe the 9V preamp will do that. I just don’t know very much about impedance, especially when the other pickups are magnetic
@@darrellgreen3592 My point was simply that you will need a battery for the circuit.
Given what you're tring to do I would recommend trying out the piezo wired directly to the preamp you puchased. Worst case, it will sound a bit tinny; you're not going to damage anything. The main concern with using both circuits together is that you might get unwanted saturation.
@@darrellgreen3592 There's three types of impedance: Inductive, capacitive and resistive. Inductive and capacitive are like opposites of each other, resistive is neutral.
Magnetic pickups have mostly inductive impedance and a bit of resistive, meaning that they naturally lose high frequencies and using a buffer (conditioning the signal as you say) helps preserve the high frequencies. Piezos have mostly capacitive impedance, meaning that they naturally lose low frequencies and buffering helps preserve the low end.
Excelente muchas gracias
what if you combined this with your aluminum foil condenser microphone? Would it reduce the noise issues there?
Yes, probably, particularly if I built the circuit into the mic with short wires on the low level side. Unfortunately that mic only existed for a short period of time after the video was made :P
@@Psychotenuse awh, I guess I'll just have to replicate it to truly find out :D
Just to clarify, what do you mean by the "low level side"? Is that the short end of the tube?
No, the wires going from the foil to the circuit. Low signal level.
@@Psychotenuse ah. If I'm getting this correctly, are you saying that the longer wires are acting like antennas, which is leading to white noise?
Haha, yes. That's where noise tends to come from in audio.
Is 9-12 volt okay to that corcuit
should work well, but the gain will be rather a lot. For simpler circuits it's generally better to use batteries.
I already build it but there is static noise and hiss can you please tell me why?
This straightforward design is exactly what I am looking for for my project, which is a bass uke with rubber/latex strings and a piezo disc transducer. How do you think it will sound on the lower 400-4k frequencies? should I change any of the parts values? I plan to use a rechargeable CR123a in place of the coin cell, any issues you can see with that? Thanks for the great content!
The RC rolloffs on this are well below 20Hz, so there should not be a problem at low frequencies specifically. I see no reason that the rechargeable battery would be problem either, as long as the charging is done by removing the battery from the device and putting it into an off-the-shelf li-ion battery charger. If you want to make the device plug-in rechargeable you would have to include li-on charging circuitry.
@@Psychotenuse Thanks! Other comments have asked about adding a pot to provide gain control but I really appreciate the simple fixed-gain setup in my application since I am installing it inside the instrument and don't want to make holes for knobs. As you suggest I will use a battery holder for the CR123 and remove the battery to charge it. Have been watching some of your other videos and there are some very cool projects. Love the channel!
Nice presentation style
Keep it up
Thanks!
Great video! What other transistor could we replace the 2n7000? anyone?
Glad you liked it!
Any n-channel enhancement type signal MOSFET should work. The bs170, for example.
@@Psychotenuse thank you so much, you are the best!
@@Psychotenuse subscribed! thanks again
where do i find that mosfet?
You can order it from Digikey etc.
Which transistor can be used
basically any n channel enhancement type signal mosfet.
Thanks a lot
cool project, did you record it directly lineout to the computer or by giving to an amp and record by mic?
This was a DI recording
@@Psychotenuse I don't know what that is could you tell me
@@infinitx1330 Oh, sorry! Yes it is line out as you say. DI stands for direct injection (I mostly just say direct input though lol).
use a filter stade capacitors filters for that noise
What do you have in mind?
@@Psychotenuse use a 100kΩ or a 1MΩ resistor in parallel in input capacitor like a CR filter and in output use a 100 nF and one 10μF capacitor up to 50μF
Wohooo Riju!!
great job😊
Thanks :)
Hey nice video... I have a dought though... I made a magnetic pickup my own and using it as the pickup for my guitar... It works fine but has less gain..
So if i make this circuit will it be ok with the magnetic pickup? Like will there be any noise or over gain?... Also how long will i get the battery life of 3.3v.. Just to make sure will i be needing a power..switch
Thank You
The gain is somewhere in the neighborhood of 10.
does it have to be electrolitic caps? Wouldn't it be easier to use non polarised film or box caps? Also in the voice over you say a 10nf cap and a 100uf cap. However the schematic says 100nf and 100uf?
Nice preamp, surprisingly clear and decent quality considering cost of parts. thanks for the vid.
I did actually use a 10nF capacitor on the input, thanks for pointing that out! I will fix the number in the schematic. The output capacitor is electrolytic simply because unpolarized capacitors with such high capacitance values are generally too big and expensive.
@@Psychotenuse wow, wasn't expecting a response that quickly. Great thank you for the info, i'll have to make a couple!
Cheers!
@@Psychotenuse Also, any idea on battery life with one of these 3v disc batteries?
Hm. I don't know, but many hours, probably. Let's see. So the battery is discharging through an effective load of about of 1k ohm (order of magnitude). The voltage is 3V so the current is about 3mA. Divide the (according to google) 200mAh capacity of one of these cells by this current value, and we get 66 hours. Not sure how accurate that is, but it's a first approximation, I guess.
@@Psychotenuse cool thank you ever so much. Last device I built was tube and on a mains powered power supply so I didn’t have to worry about battery power.
If you can find time. Build yourself a valvecaster. I built one as a valve preamp paired with a solid state poweramp similar to the valvestate amps of the 90s. Sounds half decent. Easy enough and I’m sure you could do one very well! Try it
Diagram pleas
2n7000 transistor equivalent
The bs170 should work
Hey mate, this is exactly what i need. Just one question: Can this circuit run fine on 5v, or do you need different components or capacitors for that?
I want to power this using a 5v power bank of phone. Will it work?
Thank you for all the amazing projects you have done.
It should work fine on 5 volts, if that's what you want to do.
@@Psychotenuse ah great, thank you.
there is a boost converter in those power banks which can be very noisy
Couldn't finish, the solding made be cringe, thans for the video.
please do NOT bend leads by hand - use pliers so it does not stress the lead/internal connection
Thanks for the advice :)
Hey man, I was asking for your help with the headphones amp. You said to email you but I don’t know what your email is. Would you let me know?
Go the about section on my channel page and click on business email
@@Psychotenuse no there isn’t lol
Oh I see, it doesn't show up on mobile. It's psychotenuse at gmail dot com.
@@Psychotenuse ok I found it. For some reason on the mobile application it is not listed and there is no option for it. I'll reach out to you shortly. Thanks