DIY Tuner possibility?

[hooperharp]

Hello, Andy Hooper here.
So I found no information on a DIY tuner on the net. Yes, they are the cheapest of the pedals and even cheaper for those you stick on your guitar's headstock, yet I guess it would be pleasing to make one. I bought an orange micro crush and it has a built in tuner. I opened it a while ago and couldn't find any information on the net on the chip which i guess is used for the tuner part. Anybody has any idea on this? tried it? I'll open it again tomorrow and give you the information on what I find inside. 

[bcalla]

I've looked but there is nothing that looks very useful.  Google these:
Jesper's Digital Guitar Tuner
The Gimmick Guitar Tuner

[Leevibe]

If you give up on building one, get yourself a sonic research turbo tuner. It is THE BEST! Easy to use, true bypass, laser quick and hyper accurate.

[kothoma]

You could build one using an Arduino. Here a few links I collected over time:

Two projects based on auto-correlation (probably the best way to do it):
- http://www.instructables.com/id/Reliable-Frequency-Detection-Using-DSP-Techniques/?ALLSTEPS (http://forum.arduino.cc/index.php?topic=195085.0)
- http://pastebin.com/2rPJFu4B

And here one way to get audio into the Arduino:
http://www.instructables.com/id/Arduino-Audio-Input/?ALLSTEPS

And a simpler (but less accurate) way for frequency detection:
http://www.instructables.com/id/Arduino-Frequency-Detection/?ALLSTEPS


See also this Arduino project (improved autocorrelation):
http://deambulatorymatrix.blogspot.ca/2010/11/digital-chromatic-guitar-tuner-2008.html
http://recherche.ircam.fr/equipes/pcm/cheveign/pss/2002_JASA_YIN.pdf

[m-Kresol]

I like the polytune systems. They do a fourrier transformation of your signal to analyze all the strings at once! Just a short explanation on fourrier analysis (I like it so much, I just need to share it. From one of my university profs): "imagine you have a christmas tree with a lots of little bells on it. to find out the sound of it you could ring each bell alone. Or you hit the whole thing with a baseball bat and do fourrier of the messy output that all bells make together. Fourrier will give you frequencies of every single bell."

I thought about taking my korg tuner apart and make it true bypass. Shouldn't be too hard...

[kothoma]

Well, I found the TC Electronic Polytune very inaccurate. It is better in single mode which regularly gives different results from poly mode.

[marmaliser]

Well, I found the TC Electronic Polytune very inaccurate. It is better in single mode which regularly gives different results from poly mode.

Totally agree, its only useful in poly mode when you are putting new strings on a floyd rose

[RobA]

Hello, Andy Hooper here.
So I found no information on a DIY tuner on the net. Yes, they are the cheapest of the pedals and even cheaper for those you stick on your guitar's headstock, yet I guess it would be pleasing to make one. I bought an orange micro crush and it has a built in tuner. I opened it a while ago and couldn't find any information on the net on the chip which i guess is used for the tuner part. Anybody has any idea on this? tried it? I'll open it again tomorrow and give you the information on what I find inside. 

I'd be really interested to know what chip they are using.

As far as doing the DIY tuner goes, it just seems that there isn't a whole lot of payoff for what would be quite a bit of work to develop. That and the fact that we are still only at the early stages of using digital for DIY probably contribute to there not being a whole lot of stuff out there already done. There's also the point the the economies of scale still hit the digital side of things pretty hard -- a moderately powerful DSP chipset will cost about the same as a complete headstock tuner.

Still, I agree with you that it would be a fun project. The point that it is a good starting point to launch a pitch-to-MIDI converter is also a benefit  .

I like the polytune systems. They do a fourrier transformation of your signal to analyze all the strings at once! Just a short explanation on fourrier analysis (I like it so much, I just need to share it. From one of my university profs): "imagine you have a christmas tree with a lots of little bells on it. to find out the sound of it you could ring each bell alone. Or you hit the whole thing with a baseball bat and do fourrier of the messy output that all bells make together. Fourrier will give you frequencies of every single bell."

If you go the route of using an FFT to do a polyphonic tuner, the FFT is going to be the trivial part. All the fun's going to happen before and after the FFT. Just think of the code to try and sort all the spectral peaks and assign them to the right pitch -- while they are moving. Before you get to the FFT, you have to figure out which parts of the signal are transients -- the attack phase for multiple string hits. And all of that while the harmonics of the notes overlap! And that's before you throw in trying to do it for open tunings. Polyphonic pitch detection in near real time is a hard problem. If you go from near real time, like a tuner, to real time, like a polyphonic pitch-to-MIDI converter, it gets really tough.

[jimijam]

the korg pitchblack poly is crazy accurate and has the greatest display i've seen on a pedal tuner

[jkokura]

My Polytunes (plural) do great for me. I use the poly element to see what strings seem to be the worst culprits (hard to hear in a band environment) then do a spot check on each individual string needing help.

DIY tuners sounds fun though, but if you can get headstock tuners for under $20...

Jacob

[Clayford]

the korg pitchblack poly is crazy accurate and has the greatest display i've seen on a pedal tuner

While I loved my pitchblack it became a tone generator (and even told me it was a D!)- They claimed it was interference and normal operation, until I sent a video to them showing the operation. They even claimed my 1spot caused the "damage", that a 1700mah device powering a device that only needed 100ma ...    I tried several avenues, all to no avail. I now refuse to give them my custom.

My Polytune 2 does a fantastic job. No nonsense about not using a TC Electronics power supply will void the warranty.  Yes Poly mode isn't as accurate as single note mode, (would you really expect poly vs single strobe style to be?) but it will get you in tune enough on stage without fail in a pinch.

[hooperharp]

Hey guys, thanks ffor replying. So, the chip I thought to be part of the tuner is actually part of the amp, a TDA7267. There is a second board I hadn't noticed the first time I opened it that is connected to the LEDs and has a black blob on it, so I guess the micro controller (is it one?) is in there. And yes, I will buy a tuner pedal at some point, they're not expensive. I just thought it'd be cool to make one and I thought after looking around on the net that the only thing keeping people away from a project like this was the price point of tuners. Ok, soy from what you guys say Arduino would be a good place to start? I know nothing about programming yet I'm willing to learn and this could be a good place to start (a tuner).
Also...I will buy a tuner...but this is an interesting project I guess.
Thanks for all the useful links and info again!!