bwps
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Post by bwps on Jul 13, 2017 18:41:36 GMT -5
High JohnH!
I'm impressed with your job. I and a friend of mine are trying to create a piezo preamp based pretty much on yours.
On the other hand, even though the sound is great, as a matter of fact, I still miss those air resonance frequencies, just as is the case of Graphtech. I think that is the only thing that is missing as compared to the trademark model.
How can I find these?
Will you help me out.
All the best.
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Post by JohnH on Jul 13, 2017 23:03:20 GMT -5
Hj bwps - welcome to GN2. I also found that I couldnt get quite as much 'air' and 'space' with my solid-body guitar and crude piezo than I wanted. What type of guitar and piezo are you using?
Some ideas
The three tone presets allow highs to be boosted.
Playing through a full range PA sounds better than a guitar amp for this.
Also after the guitar, it sounds good with a little chorus or even an acoustic sim setting on a processor (ie much better than a normal electric through a sim).
Plus, the acoustic tone is particularly sensitive to fresh strings.
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bwps
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Post by bwps on Jul 14, 2017 12:01:53 GMT -5
Hj bwps - welcome to GN2. I also found that I couldnt get quite as much 'air' and 'space' with my solid-body guitar and crude piezo than I wanted. What type of guitar and piezo are you using? Some ideas The three tone presets allow highs to be boosted. Playing through a full range PA sounds better than a guitar amp for this. Also after the guitar, it sounds good with a little chorus or even an acoustic sim setting on a processor (ie much better than a normal electric through a sim). Plus, the acoustic tone is particularly sensitive to fresh strings. Your fast. Thanks for the prompt reply by the way. I'm afraid to tell you but I have a question here. Do you mind answering it? 1 - which amp has been used in "piezoblues" and "dear prudence" tracks? Were the strings fresh? I noticed more "air" in the first 3 strings more than the rest. If Graphtech has done a good job here, you will also do, since both are piezo loaded devices. If you have a clue on how to spot these resonance sounds, fire away. I have not tested yet, i checked your files only. A friend of mine, more acquainted with electronics, is doing the hard work. As soon as he finishes the preamp, I can tell you the outcomes. My guitar is an Ibanez Rg520qs, and I'll plug it into my amp's clean channel, hooked up to two V30 speakers.
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Post by JohnH on Jul 14, 2017 15:12:42 GMT -5
Thanks for listening to those. There were recorded directly into a mixer set neutrally, then to the pc. So they are as near as possible to what comes out of the guitar and what you would hear if you played into a full range amp or PA system. I think that will be key to getting nearest to a full acoustic sound.
A guitar amp will still sound good but the speakers don't respond to high frequencies over about 5khz. I also like V30's in my amp and cab. When I use that set up with either this piezo hybrid or with my real acoustic, I switch on a couple of piezo tweeters that I built into the cab, but that is another project. PA is better though.
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bwps
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Post by bwps on Jul 15, 2017 7:40:51 GMT -5
Thanks for listening to those. There were recorded directly into a mixer set neutrally, then to the pc. So they are as near as possible to what comes out of the guitar and what you would hear if you played into a full range amp or PA system. I think that will be key to getting nearest to a full acoustic sound. A guitar amp will still sound good but the speakers don't respond to high frequencies over about 5khz. I also like V30's in my amp and cab. When I use that set up with either this piezo hybrid or with my real acoustic, I switch on a couple of piezo tweeters that I built into the cab, but that is another project. PA is better though. In a fact I've listened extensively to all your archives. Paid very much attention to each tiny detail. The sounds are really amazing and are not an "acoustic guitar on an electric one" kinda thing: it really have an authentic acousti-tonal sound. Really! However, speaking my mind, sometimes it sounds like a budget acoustic sounding guitar. For the time being, especially because of the low number of samples here, that's all I can say. Maybe more fluid and dynamic ones would fit in the missing data as to a more complete observation. I'm here to make this project stand out a little more. It is almost perfect, but adding some frequencies here and there will make it as perfect as the mainstream versions. I have a reasonably good interface and will not plug it into my amp's cabinet next time. Other than the software you used, could you point out any other programs?
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Post by JohnH on Jul 15, 2017 8:05:05 GMT -5
i think I took mh project as far as I could with the parts I had and so I havent really got any more suggestions. id suggest you get yours running and then think abouf how tk tweak it then.
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bwps
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Post by bwps on Jul 15, 2017 9:07:40 GMT -5
i think I took mh project as far as I could with the parts I had and so I havent really got any more suggestions. id suggest you get yours running and then think abouf how tk tweak it then. Ok, then. Sorry to bother!
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bwps
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Post by bwps on Jul 18, 2017 10:44:23 GMT -5
Thanks for listening to those. There were recorded directly into a mixer set neutrally, then to the pc. So they are as near as possible to what comes out of the guitar and what you would hear if you played into a full range amp or PA system. I think that will be key to getting nearest to a full acoustic sound. A guitar amp will still sound good but the speakers don't respond to high frequencies over about 5khz. I also like V30's in my amp and cab. When I use that set up with either this piezo hybrid or with my real acoustic, I switch on a couple of piezo tweeters that I built into the cab, but that is another project. PA is better though. John I've noticed that the piezo's capacitance value is 10nf. I am thinking about making it as a combo, preamp/mixer plus piezo loaded saddles, very similar to these, as follows: www.jonbondy.com/Piezo.htmYour project is based on one piezo only. If ever I introduce six more piezos into the board, what about the rest of the circuit? Which things should I change?
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Post by JohnH on Jul 18, 2017 15:28:07 GMT -5
The capacitance of my piezo was 20nF, it is quite a large element. Next to it is R2 which I used as 150k, which drains away unwanted sub-bass signals. If your piezo is smaller, then R2 might be better larger.
The biasing resistors at each jfet may be best at one value different depending on your jfets, which are often inconsistent. THe idea is to get about 5V at the drain, though the values shown should work OK.
The whole circuit was developed to suit the tones I was getting. It has some adjustment built in, but it would be best to try to mock it up and test it and adjust values before building it into the guitar.
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bwps
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Post by bwps on Jul 20, 2017 15:38:58 GMT -5
The capacitance of my piezo was 20nF, it is quite a large element. Next to it is R2 which I used as 150k, which drains away unwanted sub-bass signals. If your piezo is smaller, then R2 might be better larger. The biasing resistors at each jfet may be best at one value different depending on your jfets, which are often inconsistent. THe idea is to get about 5V at the drain, though the values shown should work OK. The whole circuit was developed to suit the tones I was getting. It has some adjustment built in, but it would be best to try to mock it up and test it and adjust values before building it into the guitar. Thanks again man, that was quite helpful. In a fact the piezo sounds pretty much like a mic'd guitar. Simply awesome! You put your piezo disc in the backbox. Would it sound different if we put it unde saddles or not?
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bwps
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Post by bwps on Jul 20, 2017 15:47:31 GMT -5
I'm still tweaking the bridge height, looking for the best possible action. I have the nut set and the frets are all level. The piezo is an under saddle. It resembles an acoustic bridge, but the bridge piece is brass. I'm going slow with it, just taking off a little at a time. I don't want string buzz. I'll try to get some pictures posted and as soon as I get everything set, I'll post a sound clip. I also made a small 5 watt cigar box amp to go with it. I'll post those pictures too. I saw a review recently by Rob Chapman on a guitar with a "Fishman Powerbridge", which sounds much like these. Basically an under saddle transducer with a preamp. Hi boctok. I'm aware it's been a while when you last wrote here. I'm sorry for that I have come across this piezo system and liked a lot. In Addition, I have noticed you have also installed it. Which are your overall impressions as to dynamics and post eqs - mixer, eq pedals, Daws? Is there any difference of sound according to the place where the piezo is fixed to?
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Post by JohnH on Jul 20, 2017 16:16:11 GMT -5
i placed my piezo behind the trem block, and let the string pressure squeeze it to get good coupling. It was an easy work-around, since it allowed the sound of all strings to get combined at a single point. But of course tbe trem was then blocked. My system depends on contact from block to body via the piezo.
Putting piezos under tbe saddles is tbe usual way and should be better. It needs 6 seperate elements (or in theory, one long element) to capture each string. So it might sound different.
In any case, yours will sound different to mine and that's why I suggest to be ready yo experiment with the circuit rather than just build it as I drew it.
A good way to start would be to build the piezos in and test their sound as-is, maybe via a simple buffer (eg just the first circuit stage, or tbrough any non-true bypass pedal switched off). See what tbe basic tone is like and also how the loudness compares to the mag pickups. That approach will also get you a result you can test quickly.
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bwps
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Post by bwps on Jul 20, 2017 16:29:24 GMT -5
i placed my piezo behind the trem block, and let the string pressure squeeze it to get good coupling. It was an easy work-around, since it allowed the sound of all strings to get combined at a single point. But of course tbe trem was then blocked. My system depends on contact from block to body via the piezo. Putting piezos under tbe saddles is tbe usual way and should be better. It needs 6 seperate elements (or in theory, one long element) to capture each string. So it might sound different. In any case, yours will sound different to mine and that's why I suggest to be ready yo experiment with the circuit rather than just build it as I drew it. A good way to start would be to build the piezos in and test their sound as-is, maybe via a simple buffer (eg just the first circuit stage, or tbrough any non-true bypass pedal switched off). See what tbe basic tone is like and also how the loudness compares to the mag pickups. That approach will also get you a result you can test quickly. Im almost finishing the board. You fixed your piezo to the trem block with pressure. I thought of three distinct ways: gluing it to the trem block, placing it between the block and the under side of the bridge, or just fixing it under the saddles. I'm not sure the best place to put it in. Could you tell me more? That string buzz, typical acousti-electrical guitars, is achievable by means of dynamics?
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Post by JohnH on Jul 20, 2017 17:31:15 GMT -5
my belief is that to get a full tone, the piezo should be placed between something that is vibrating and something that is fixed, so it feels changes of pressure through it. So between saddle and bridge is good and between trem block and body worked too. But id expect tbat just glued to the block etc, youd get less signal.
Need to experiment.
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bwps
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Post by bwps on Jul 21, 2017 8:59:46 GMT -5
my belief is that to get a full tone, the piezo should be placed between something that is vibrating and something that is fixed, so it feels changes of pressure through it. So between saddle and bridge is good and between trem block and body worked too. But id expect tbat just glued to the block etc, youd get less signal. Need to experiment. Man Youve been of great help and real nice getting back to me on various issues. Thanks a lot. As to experimenting, your damn right. I have thought of installing two or 3 piezo discs into my guitar. Will your preamp support it?
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Post by JohnH on Jul 21, 2017 14:58:52 GMT -5
The preamp should work with multiple piezos. Loudness will be different if they are in series or parallel. You could place them and test one at a time, then combine those that get a good signal.
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bwps
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Post by bwps on Jul 27, 2017 13:46:21 GMT -5
The preamp should work with multiple piezos. Loudness will be different if they are in series or parallel. You could place them and test one at a time, then combine those that get a good signal. Thanks again. I got a situation here. My friend has just built the board. However, he can't get the volume working properly with the piezo disc located as it is in the original schematics. The volume is too low, he said. Also in his words: at the last stage, right at the transistor' s input for the piezo's output, the gain is too low. The first photo illustrates the problematic gain stage. The second and third are the in process board. He's made a question: 1 - how to solve this and which component (s) should I tweak? Attachments:
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Post by JohnH on Jul 27, 2017 15:27:06 GMT -5
I think he should prove that the board is working properly, the jfet's are biased properly (about 5V at the drain for the gain stages or 5V at the source for the buffer stages) - or else adjust the biasing resistors. You can feed a normal pickup through the piezo input and it should make a strong sound.
Also, try plugging your piezos direct to your amp. You should get something. Then connect to the preamp board and listen to the signal after the first jfet. It should be considerably louder.
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bwps
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Post by bwps on Jul 27, 2017 18:08:41 GMT -5
I think he should prove that the board is working properly, the jfet's are biased properly (about 5V at the drain for the gain stages or 5V at the source for the buffer stages) - or else adjust the biasing resistors. You can feed a normal pickup through the piezo input and it should make a strong sound. Also, try plugging your piezos direct to your amp. You should get something. Then connect to the preamp board and listen to the signal after the first jfet. It should be considerably louder. Thanks once again!! Just one more thing: he mentioned that whenever he took the 150k resistor out and put it back on the board, he would notice a sudden,fast and high increase in volume. He's there trying to find the tough guy. I'll keep you posted.
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Post by JohnH on Jul 27, 2017 18:28:03 GMT -5
Thats a good clue. That 150k went in just to suit my big round piezo. It needs to be there but it can be much higher. Could be anything up to say 3.3M. Then reduce if you get too much sub-bass thumps.
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Post by Charlie Honkmeister on Jul 27, 2017 20:46:02 GMT -5
Just as some new information, not necessarily a plug, I have found this piezo bridge to work well: brennerusa.com/product-category/piezo-one/This uses a single acoustic guitar saddle pickup (Artec) with 6 crystals in a common assembly with a single cable. Models are for Strats and Teles with modern string spacing, but they have been working on replacements for a wraparound Gibson type bridge. Besides putting one on a Strat, I have put one on a PRS SE trem and it works well there after milling a slot on the side for the cable routing. The bridge is designed so that each string saddle "finger" extension only contacts the piezo directly on its own element. Intonation and fingerboard radius compensation are machined in and can achieve good intonation and will work fine for Fender scale length (or PRS) and a normal range of string gauges. The entire bridge can adjust fore and aft, and up and down, in a similar way to a Gibson wraparound tailpiece. Pricing is extremely good on this unit ($65.00 US) compared to L.R. Baggs, Graphtech, and Fishman piezo bridges with individual piezo saddles (>$200.00). I have bought two of these and have a third going on my next Tele build. JohnH's preamp as well as other piezo buffers/preamps will work fine with this piezo. Fair disclosure: I found this bridge on Ebay, was intrigued by the design and pricing, bought one, called Mark Brenner to talk about it, and we ended up friends. But the innovative product came first. -Charlie
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bwps
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Post by bwps on Aug 4, 2017 12:23:33 GMT -5
Thats a good clue. That 150k went in just to suit my big round piezo. It needs to be there but it can be much higher. Could be anything up to say 3.3M. Then reduce if you get too much sub-bass thumps. Hi John. My friend has just solved the issues. He inverted some resistor values, and that is why he was getting no sound lol Thanks for your valued time once again. By the way we are now working on it to add our frequency tastes to the device. We would like to get rid of that 'banjo' sound. Which frenquencies should we tweak?
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Post by JohnH on Aug 4, 2017 15:08:30 GMT -5
Thats a good clue. That 150k went in just to suit my big round piezo. It needs to be there but it can be much higher. Could be anything up to say 3.3M. Then reduce if you get too much sub-bass thumps. Hi John. My friend has just solved the issues. He inverted some resistor values, and that is why he was getting no sound lol Thanks for your valued time once again. By the way we are now working on it to add our frequency tastes to the device. We would like to get rid of that 'banjo' sound. Which frenquencies should we tweak? Well that's good progress. So are you now testing it in the guitar and hearing how it sounds? Before fine tuning, it would be good to know that your basic levels from the piezo and magnetic systems are close enough in volume to be useable. Then, its all down to adjusting tone and I expect it will be different in your case. If you have the full circuit built, then there are 3 EQ presets. R30 is a high-pass filter to control treble, it only lets signals through that are above a frequency determined by R30 and C6. Reduce R30 and this frequency rises. Similarly, bass is controlled by a low pass filter R29 and C7, increase R29 to lower the frequency below which it passes the bass sound. R13 pans between the treble and the bass. If you read through the first post, you'll see how in my case the main tonal fix that was needed was to knock down a hump at around 700hz. This was done by moving these two filters apart so there is a gap in the middle. Id recommend trying to test it the same way I did. Run the signal into the line-in on a pc and record it in an audio program such as Audacity (its free). Then you can see where your peaks are and decide how to set up the filter. Duncan's Tone Stack Calculator (also free)can be set up to match the tone stack in this circuit. There's a couple of other tweaks that you can try if you need them: If you are generally short of piezo volume compared to magnetic, reduce R23 at the first transistor Q1. If the piezo is lacking bass, increase the value of R2 (the 150k, as discussed before) If you need a little more very high frequencies add a small cap across R25 at Transistor Q4, maybe about 3.3nF.
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bwps
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Post by bwps on Aug 4, 2017 16:17:11 GMT -5
Hi John. My friend has just solved the issues. He inverted some resistor values, and that is why he was getting no sound lol Thanks for your valued time once again. By the way we are now working on it to add our frequency tastes to the device. We would like to get rid of that 'banjo' sound. Which frenquencies should we tweak? Well that's good progress. So are you now testing it in the guitar and hearing how it sounds? Before fine tuning, it would be good to know that your basic levels from the piezo and magnetic systems are close enough in volume to be useable. Then, its all down to adjusting tone and I expect it will be different in your case. If you have the full circuit built, then there are 3 EQ presets. R30 is a high-pass filter to control treble, it only lets signals through that are above a frequency determined by R30 and C6. Reduce R30 and this frequency rises. Similarly, bass is controlled by a low pass filter R29 and C7, increase R29 to lower the frequency below which it passes the bass sound. R13 pans between the treble and the bass. If you read through the first post, you'll see how in my case the main tonal fix that was needed was to knock down a hump at around 700hz. This was done by moving these two filters apart so there is a gap in the middle. Id recommend trying to test it the same way I did. Run the signal into the line-in on a pc and record it in an audio program such as Audacity (its free). Then you can see where your peaks are and decide how to set up the filter. Duncan's Tone Stack Calculator (also free)can be set up to match the tone stack in this circuit. There's a couple of other tweaks that you can try if you need them: If you are generally short of piezo volume compared to magnetic, reduce R23 at the first transistor Q1. If the piezo is lacking bass, increase the value of R2 (the 150k, as discussed before) If you need a little more very high frequencies add a small cap across R25 at Transistor Q4, maybe about 3.3nF. John, all I can say is that you rule man!!!! Your information always come in handy! Yes, we tested it in the guitar. It sounds good, but lacks some tweaking in the treble and middle frequencies areas in order to sound more electric-like. we are also trying to build piezo loaded saddles to get better and definitive results. I truly believe that we're gonna make it. we're not trying to exactly match GraphTech's results, but make a stand in the middle of acoustic and electric sounds. As soon as the sound files are decent, I'll let you know.
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Post by Charlie Honkmeister on Aug 4, 2017 17:59:00 GMT -5
Well that's good progress. So are you now testing it in the guitar and hearing how it sounds? Before fine tuning, it would be good to know that your basic levels from the piezo and magnetic systems are close enough in volume to be useable. Then, its all down to adjusting tone and I expect it will be different in your case. If you have the full circuit built, then there are 3 EQ presets. R30 is a high-pass filter to control treble, it only lets signals through that are above a frequency determined by R30 and C6. Reduce R30 and this frequency rises. Similarly, bass is controlled by a low pass filter R29 and C7, increase R29 to lower the frequency below which it passes the bass sound. R13 pans between the treble and the bass. If you read through the first post, you'll see how in my case the main tonal fix that was needed was to knock down a hump at around 700hz. This was done by moving these two filters apart so there is a gap in the middle. Id recommend trying to test it the same way I did. Run the signal into the line-in on a pc and record it in an audio program such as Audacity (its free). Then you can see where your peaks are and decide how to set up the filter. Duncan's Tone Stack Calculator (also free)can be set up to match the tone stack in this circuit. There's a couple of other tweaks that you can try if you need them: If you are generally short of piezo volume compared to magnetic, reduce R23 at the first transistor Q1. If the piezo is lacking bass, increase the value of R2 (the 150k, as discussed before) If you need a little more very high frequencies add a small cap across R25 at Transistor Q4, maybe about 3.3nF. John, all I can say is that you rule man!!!! Your information always come in handy! Yes, we tested it on the guitar. It sounds good, but lacks some tweaking in the treble and middle frequencies areas in order to sound more electric-like. we are also trying to build piezo loaded saddles to get better and definitive results. I truly believe that we're gonna make it. we're not trying to exactly match GraphTech's results, but make a stand in the middle of acoustic and electric sounds. As soon as the sound files are decent, I'll let you know. There's one more tweak to keep in mind on a piezo should you ever need it. If you put a small value capacitor (in the 1000 pF-.01 uF range for most piezo pickups) directly across (shunting) the piezo element, this pads down the output (reduces output level to better match the mag output or not overload the preamp,) can "tame" too-shrill highs, and also make the piezo less sensitive to resistive loading (giving more bass response for a given load resistance.) I'm glad as well you are making good progress on your piezo work.
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bwps
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Post by bwps on Aug 6, 2017 7:05:30 GMT -5
John, all I can say is that you rule man!!!! Your information always come in handy! Yes, we tested it on the guitar. It sounds good, but lacks some tweaking in the treble and middle frequencies areas in order to sound more electric-like. we are also trying to build piezo loaded saddles to get better and definitive results. I truly believe that we're gonna make it. we're not trying to exactly match GraphTech's results, but make a stand in the middle of acoustic and electric sounds. As soon as the sound files are decent, I'll let you know. There's one more tweak to keep in mind on a piezo should you ever need it. If you put a small value capacitor (in the 1000 pF-.01 uF range for most piezo pickups) directly across (shunting) the piezo element, this pads down the output (reduces output level to better match the mag output or not overload the preamp,) can "tame" too-shrill highs, and also make the piezo less sensitive to resistive loading (giving more bass response for a given load resistance.) I'm glad as well you are making good progress on your piezo work. Thanks Charlie, and sorry I took so long to get back to you. First, your recommendations will be taken into consideration when the time comes. I and my friend are now trying to soothe some frequencies and boost others. John's preamp stands out, but to our ears, it lacks some tiny features, devil is in the details. We are mounting the piezo loaded saddles in order to find out whether those metallic, string-hitting frequencies are in fact due to the strings themselves or it's just a frequency-modeling feature a preamp must have. In order to achieve this, the piezo saddles will definitely guide us through. The preamp misses some bass thing and compression, needs some cutoff in the middle areas and also a boost in high frequencies. We don't want to bother you guys, but think it's necessary to keep you posted, since the project turned out to be available in this forum.
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Post by Charlie Honkmeister on Aug 17, 2017 21:28:55 GMT -5
There's one more tweak to keep in mind on a piezo should you ever need it. If you put a small value capacitor (in the 1000 pF-.01 uF range for most piezo pickups) directly across (shunting) the piezo element, this pads down the output (reduces output level to better match the mag output or not overload the preamp,) can "tame" too-shrill highs, and also make the piezo less sensitive to resistive loading (giving more bass response for a given load resistance.) I'm glad as well you are making good progress on your piezo work. Thanks Charlie, and sorry I took so long to get back to you. First, your recommendations will be taken into consideration when the time comes. I and my friend are now trying to soothe some frequencies and boost others. John's preamp stands out, but to our ears, it lacks some tiny features, devil is in the details. We are mounting the piezo loaded saddles in order to find out whether those metallic, string-hitting frequencies are in fact due to the strings themselves or it's just a frequency-modeling feature a preamp must have. In order to achieve this, the piezo saddles will definitely guide us through. The preamp misses some bass thing and compression, needs some cutoff in the middle areas and also a boost in high frequencies. We don't want to bother you guys, but think it's necessary to keep you posted, since the project turned out to be available in this forum. If you're rolling your own piezo saddles and have some metallic, tinny, sounds coming out of the piezos, I've found that piezo saddle to metal contact (bridge plate, not strings) can cause this. I don't know how you're rolling these saddles so can't be more specific unfortunately. While you are experimenting, you might want to put some teflon pipe tape, either the standard thin kind or the 3 mil thick kind, anywhere that there's a significant area of metal to metal contact. The tape fills in the microscopic surface irregularities in the metal contact surfaces, provides a little bit of high frequency damping, and may help with zinginess or metallic high frequency harshness without impacting basic tone or output for the worse. Plus it's cheap and reversible. On some of the commercial stick-on piezo discs, the glue or adhesive probably provides this function and, as an anecdotal confirmation, at least one guy who makes high-end contact piezo discs, told me at NAMM that the actual adhesive he used was part of the reason his piezo sounded good. When you're doing piezos you need to look at the mechanical interface and attachment of the piezo first IMHO, then go for EQ when you know you have a good basically full range signal.
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bwps
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Post by bwps on Feb 8, 2018 9:30:52 GMT -5
Hi John. My friend has just solved the issues. He inverted some resistor values, and that is why he was getting no sound lol Thanks for your valued time once again. By the way we are now working on it to add our frequency tastes to the device. We would like to get rid of that 'banjo' sound. Which frenquencies should we tweak? Well that's good progress. So are you now testing it in the guitar and hearing how it sounds? Before fine tuning, it would be good to know that your basic levels from the piezo and magnetic systems are close enough in volume to be useable. Then, its all down to adjusting tone and I expect it will be different in your case. If you have the full circuit built, then there are 3 EQ presets. R30 is a high-pass filter to control treble, it only lets signals through that are above a frequency determined by R30 and C6. Reduce R30 and this frequency rises. Similarly, bass is controlled by a low pass filter R29 and C7, increase R29 to lower the frequency below which it passes the bass sound. R13 pans between the treble and the bass. If you read through the first post, you'll see how in my case the main tonal fix that was needed was to knock down a hump at around 700hz. This was done by moving these two filters apart so there is a gap in the middle. Id recommend trying to test it the same way I did. Run the signal into the line-in on a pc and record it in an audio program such as Audacity (its free). Then you can see where your peaks are and decide how to set up the filter. Duncan's Tone Stack Calculator (also free)can be set up to match the tone stack in this circuit. There's a couple of other tweaks that you can try if you need them: If you are generally short of piezo volume compared to magnetic, reduce R23 at the first transistor Q1. If the piezo is lacking bass, increase the value of R2 (the 150k, as discussed before) If you need a little more very high frequencies add a small cap across R25 at Transistor Q4, maybe about 3.3nF. Hi John. Its been a while since we last talked buT im back on track. We have decided to create a decent piezo transducer, soh were going To produce, in a handmade fashion, our own saddles. In order to do so, we have got in contact with a friend who makes little metal pieces, we asked him to do so and he agreed. On top of that, we have also bought the graphtech preamp to analyze the preamp's frequency spectrum and make the alterations on yours. If you dont mind, we'd like to proceed with the experiment. I have known many companies build both preamp and piezo loaded saddles, such as Schaller, Fishman and also Graphtech. Is there any problem if we are here on this thread planning to do a piezo stuff if others hold the official, patented permission to build and sell the piezo system?
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Post by JohnH on Feb 8, 2018 14:09:08 GMT -5
Good luck with your project. I don't know about legal issues, but id expect there is no problem building anything for private use, and also Id expect that the idea of a piezo pickup is generic enough that no-one could complain if you sold them unless you steal someones commercial design. You are welcome to adapt and use my design in any way you like, but note that it was just hacked together out of parts that I had and could understand. I'm sure there are better ways.
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Post by sumgai on Feb 8, 2018 17:06:07 GMT -5
bwps,
I think you're OK to build your own piezo-saddle designs for retail sale, that is as generic as winding a coil of wire around one or more magnets. However, specific methodolgies and/or work processes might have been patented. Best to do a patent search first, just to make sure that you aren't taking a long walk off of a short pier.
But when you say, in public print, that you are going to analyze the Graphtech Acousti-Phonic module, you might be setting yourselves up for some tears, the legal kind. To avoid that potential, I'd suggest that you do two things:
a) Buy, at retail, a similar module from each of the other companies that make these things, as many companies as you can find. I know of L.R. Baggs, Fishman, Graphtech, RMC, Fender/Roland, etc. but there are plenty of others to scope out. The reason for this is two-fold, which brings us to:
b) Analyze every one of them, not just one or two, for frequency characteristics. One, you'll not be stuck with the results of just one particular device, and two, you head off any accusations of directly copying a specific unit. A copy does not need to be built exactly like the original (same p.c. board, same components, etc. which is a clone), it need only produce the same results from a similar input - that's what gets many small-time builders* into trouble with the big boys. Moreover, by having a compendium of results to draw from, you can devise your own set of "best sounds", and market them without fear that one of the aforementioned big boys will come after you - you've taken steps to avoid producing the exact same results as their stuff, for just that reason.
And just to make it three things:
c) Take notes. Take copious notes. Take 'em and make copious copies of those notes, and store them in different locations. Many a battle plan has been sunk before even launching, due to someone forgetting to document his/their history as it happens, only to have an accuser later say that you're simply making up excuses as you attempt to defend yourself. IOW, make almighty sure you have a squeaky-clean paddle when your accuser places you in a particularly odious creek.
Bottom line: IANAL**, so seek legal advice on your own before you even think of sitting down to write a business plan to take to the bank for a loan. Failure to do so is on you, no one else. 'Nuff said.
sumgai
* As noted, by small-time I don't mean guys who are hacking together a system for their private use, I mean those who are doing it for monetary gain of any dollar amount.
** But I play one TV.
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