Is there a clean guitar test signal standard sample .wav file?

[MR COFFEE]

Hi all,

Has anyone heard of, know of, or made a set of really clean sound samples of a guitar signal that doesn't have hum, buzz, hiss, reverb overdrive, and various other extraneous adulterations all over it, to use for testing electronic projects and input into simulations?

I know RG made a decaying sine wave generator some time back, but I was looking for pristine recordings a real guitar signal. Maybe a couple recordings with single note scales (or a melody of some sort), a few recordings of a single guitar strum of a chord or two with a few different intensities on a couple different guitars, and maybe a few more consisting of repeated chord riffs of various types.

Something to allow the ear to analyze the sound characteristics of a circuit in a more objective way - and even be able to electronically subtract the input signal from the output signal and be able to visualize distortions, phase funnies, distortion harmonic structures, non-linearities, etc. on the oscilliscope. I've sat with a guitar on my lap for years tweaking circuits, but I can see advantages to a more standardized set of fixed input .wav files that we can all use in comparing circuits.

Seems everything I come across is really low quality or has reverb and other FX already all over it.

Anybody already invented this wheel, or is this something nobody does or sees value in besides me?

Or maybe I'm SOL and I'll have to try to make my own with my cheesy soundcard recording setup. It may be a challenge from all the sound samples I've listened to that sound like they were recorded by setting a cellphone in front of a guitar amp...

mr coffee

[R.G.]

At one time a close friend ran a used-guitar shop with all manner of highly regarded vintage guitars. He was going to collaborate with me on making a CD of raw recordings of old Les Pauls, Strats, Jaguars, Ricks, etc. - then he lost his lease and had to liquidate.

It's a good idea. I've mentioned a few times over the years, but never had the cache of guitars to work with. I think that someone could do well with it.

I thought of doing recordings of riffs, single notes, and chords at various settings and making the loudest chords be full range on the CD. This gets you best signal to noise. Then add a divide-down section to set the final peak after the CD line output to the actual voltage.

If you want real verissimilitude, you'd need to put an inductor after the divided-down signal; about 4H for humbuckers and 2H for single coils to simulate the source impedance of the pickups, plus about 30-100K resistance to simulate the resistance through controls. That could be done to any level, including full actual controls in the guitar's values if you wanted real accuracy.

It's a good idea. The wheel has been invented, but no one has publicly offered any for download - or sale, for that matter. A cheesy soundcard setup is way better than exists now, and could be messed with to be really good with some soundcards. Much better than the nothing that's there now.

[Digital Larry]

I've downloaded and used the pickup demo wavs from the Seymour Duncan website for this purpose.  May not be exactly what you're after, but...

[MR COFFEE]

RG -
Thanks for the reply. Your friend with the musical instrument collection sounds like he was planning to do just what I was hoping to find.

I don't know if hooking up a rig with my soundcard would be worth the effort. I have some nice guitars, but nothing like the contents of the Guitar Center vintage vault or whatever they call it. That would be the ideal.

I think your point about including the inductor and resistor network after the DAC low impedance output (and signal attenuator) is a good point. The attenuator and resistive aspect of the guitar input simulator could be partially integrated with single coil level and inductance from one tap and humbucker and inductance from another. If that could be standardized to particular inductors and resistive impedance it would be even more useful as a standard we could all reference to. 

Digital Larry,
I hadn't thought of checking out what pickup manufacturers might have available. Might do until we have a real standard to work with.
Thanks for the idea. Have you used them with your SpinCAD as an input file to the emulator?

mr coffee

[jtn191]

It isn't too hard to record a DI track and run it through SPICE. But processing the .wav does take a while

[ashcat_lt]

So the filter action of the pickups, controls, and cable into whatever input Z your using to record your samples will already be imprinted on the signal by the time you're playing it back into your circuit.  You can go ahead and run it through another filter on the way if you want, but it's just not going to be the same as plugging that guitar into that pedal.  It'll be like plugging the guitar into a buffer, then a pickup simulator, and then your pedal.  It is very likely that you will lose treble that you wouldn't otherwise lose.

All that said, if you've got the guitar then you don't really need to build a simulator.  Just lift the "ground end" of the pickup and run the signal through there!  This would probably be better if you used a piezo pickup to generate the sample, but then we might be getting even further away.

My assertion is that for most of the things we build, the components up to the first active stage are actually part of the guitar circuit.  The only way to know for sure how it will affect one given guitar is to connect it directly.  If, like many of the pedals we build, these components are chosen to have minimal impact on the guitar signal, then you don't really need a pickup sim for your tests.  Just make sure that the input the samples are recorded into looks enough like your input stage.

[scuzzphut]

I've downloaded and used the pickup demo wavs from the Seymour Duncan website for this purpose.  May not be exactly what you're after, but...

That is an awesome idea 

[GibsonGM]

I recorded my actual guitar into Cakewalk (way back when....) and burned a CD of me playing some chords, single notes, solos.....I play it back via a stereo and can adjust the volume to approximate a real level.

I also got some software that does functions, and recorded sine waves at 200Hz, 440Hz, and 1kHz, about 4 minutes each.  I use this to test filters and for audio signal tracing.  Very helpful!

[MR COFFEE]

Hi Mike,
Were  your recordings pretty clean (just guitar pickup, no preamp, etc.) without any background hiss, hum, etc?

44.1 khz sample rate or better?

Would you be willing to post some of your clips so I and others could try them as a source?

Thanks for all the great replies.

[GibsonGM]

I'll see if I can find 1) the clips and 2) a place to host them, I'd be glad to put them out.  Yes, they were pretty clean (direct into the computer!), but as such they're probably not very representative of a REAL axe.   BTW, all of this is VERY forgiving, man...sample rate, etc etc.  In the real world, you have MASSIVE variation with each part of your rig...even temperature plays a part!  Very "Monte Carlo", if you get the drift.

The little files I did were nothing fancy - I find the sine waves to be most useful!  To hear an effect, I will usually just play into it with a guitar (NO recording in my knowledge will be the same, dynamically and all that).   

Using a sine wave is cool, tho, because it doesn't have all its harmonics present....you can REALLY find out how a filter is working that way, and so on!  And also super useful for signal tracing.  These days I use an old PC with "Visual Analyser" (free program) that will let me output a sine, square, sawtooth, noise, etc.....I run that to a simple opamp variable "booster" (if you will) so I can crank it from .5VAC at the output to 2.5VAC.   I use that in conjunction with the OScope to 'see' what's going on with parts of circuits.  I consider the guitar to be somewhere between .7VAC and 1.2VAC, or so. Roughly.   That does it ALL for me, really.

I'll see if I can find, or make, something for you guys...

[Tony Forestiere]

My "Search- Fu" is very weak tonight BUT, I seem to recall a recent blind test done by a forum member on either wah pots or TS op-amps (or something of that ilk) where the tester eliminated variables in the signal chain and "fingers" by recording a nice set of tracks (single notes, light strumming, palm muting, power chords, riffage, etc.) to an audio file. He then re-amped the same signal to all of the "variables" of each test, providing (what I thought was) a true blind representation of each change. If someone can find or remember the thread, it might be close to what you are after and you might be able to get the file from them. 
Sorry. My mind is old and feeble. 

[kingswayguitar]

My "Search- Fu" is very weak tonight BUT, I seem to recall a recent blind test done by a forum member on either wah pots or TS op-amps (or something of that ilk) where the tester eliminated variables in the signal chain and "fingers" by recording a nice set of tracks (single notes, light strumming, palm muting, power chords, riffage, etc.) to an audio file. He then re-amped the same signal to all of the "variables" of each test, providing (what I thought was) a true blind representation of each change. If someone can find or remember the thread, it might be close to what you are after and you might be able to get the file from them. 
Sorry. My mind is old and feeble. 

don't mean to interrupt too badly but...
Search- Fu
That's awesome!!  Never heard that one before.
Carry on.

[GibsonGM]

...Still thinking about this topic.

Something strikes me as kind of 'off'.  It came to me.....when I play thru a small amp at low volume, sometimes I really thrash my strings (you could call that peak humbucker voltage 1.5 or something).

BUT - on stage, with my amp absolutely cranked, drive only up on 3 but master on like 7 to 10.....I play VERY gently for much of the time.  I use dynamics for every single thing.   Sometimes my output could be .5V, sometimes 1.5v.      Does that make sense?

So the question is begged....how can we accurately determine what's REALLY going on with an effect if we use recordings, in which the relationships of the dynamics are probably compressed before we input them?   Is there a lot of value in this?    How would making some really clean, well-engineered recordings do much more for us than just recording into the computer thru a buffer, into cheap software, and burning a CD like I did?

When I was a little less experienced than today, I used to sweat over a measurement difference of .02 volts, for example.  Or a current difference of 2 mA from calculated.  I didn't appreciate the variance in parts (Tolerances), nor did I realize that 8.8v is very much the same as 9.1V!   I think maybe we're at that place with the desire to REALLY nail down a super-engineered input signal...nothing in the real world will be of that tight tolerance, especially the parts we're using.     What I mean is, our "least significant digit" in 99.9% of DIY is far less precise than we often think about, and working hard to get a nicely high-tolerance signal into an effect may be wasted just because it will get swamped by the factual variances at work INSIDE the circuit.   

IOW, if you can't strum the axe on your own, any reasonable recording, level adjusted to approximate that of the guitar, should do fine, until you can get a victim to play for you while you tweak!

[PRR]

> How would making some really clean, well-engineered recordings do much more for us than just recording into the computer

I don't think the "quality of clean" is the issue.

But MOST handy guitar WAVs have been "sweetened" with compression and reverb and EQ.

It's the Result. We want the "Cause".

For pedal-tinkering we want the RAW sound right off the axe. No sugar-coating. We aren't trying to impress buyers. We know what the raw sound is like. But we do need a mechanical axe-player so we can put hands on the pedal being tinkered. And it is nice to be a *repeatable* sound, so we can A/B our changes. Does it really blip the iniital transient? Does it blip more/less with this bias change?

The level and impedance is of course an issue. Sometimes it matters, sometimes not; and a mechanical axe is one way to find out. As a simple-hack, 50K in series with a lo-Z source lets some suckages happen. And you get the level with a quick A/B against your real guitar, also by running the amp at nominal settings and getting nominal loudness.

[ashcat_lt]

And you get the level with a quick A/B against your real guitar, also by running the amp at nominal settings and getting nominal loudness.

...or by calibrating your system for unity throughput.  With decent 24 bit converters there's no good reason we have to boost or attenuate the guitar signal at any point in this process.  It's important to keep in mind that the HiZ Instrument DI (whatever your device calls it) input on most interfaces add gain with respect to its line level outputs.  That is, 1V into that hole equals more than 1V out the other end and that's really regardless of any +4/-10 settings.  The line level input will be unity through assuming that both input and output are set to the same line level standard.

[Digital Larry]

Digital Larry,
I hadn't thought of checking out what pickup manufacturers might have available. Might do until we have a real standard to work with.
Thanks for the idea. Have you used them with your SpinCAD as an input file to the emulator?

mr coffee

Hi Mr. C,

Yes I sure have used these with SpinCAD.  All the time.  What's nice is that whoever did the samples played more or less the same thing on a variety of samples.  You may have to convert them to stereo 16-bit wav as it won't eat mono files and (a bug) it won't tell you what the problem is.  But that is FAQ #1 about my program!

I'm mostly interested in what the effect sounds like on single notes in different registers and then also some barre or open chords as hard as I can hit them.   I could record my own licks and probably should.  Up until a week ago my main DAW system had been dormant for over a year.  So many things to do!

What's missing is the correlation between the peak level of the WAV file and whatever gain you might have on a real board going in.  Well, you can't solve everything with these simple approaches.  Ultimately once you got a board in hand (which I still haven't done, other than the Spin Dev board) you'd need to spend some time adjusting analog gains and then testing a variety of guitars to tweak the patches themselves.  I hate nothing more than distortion where I don't want to hear it.

Thanks,

DL

[Edit: when testing a reverb algorithm a lot of times I just want a stacatto sort of thing which may not be what is going on with these pickup sample audio clips.  In that case I open it up in my audio editor and simply mute a section to allow me to hear the echo/reverb without any signal behind it.]

[ElectricDruid]

Seems silly to post a new thread on the same topic, so I'm resurrecting this one (My apologies if you're frightened of undead Frankenthreads).

The best suggestion here as a source of clean guitar samples was Seymour Duncan's website, where there are pickup samples. Unfortunately, they don't exactly make it easy to download these samples. They're played via a AJAX player and not available anywhere else I can find.

Has anyone got any other good ideas for where one can find good, clean guitar samples for testing pedals? Or suggestions as to how I can get hold of the Seymour Duncan ones in a form I can use?

Thanks,
Tom

[blackieNYC]

I've not heard of this idea but I'm sure it's out there-I often wonder why pedal demos aren't recorded direct into a recorder, no reverb, no amp sim. Then, we could have an iPhone-to-pickup simulator, and play all these demos back as an accurate representation of one pedal going thru our very own amp. What a great way to pick your next project. Maybe?
Such a converter (a pickup sim)would allow you to play back your own clean guitar sounds (and playing style). A simple audio to usb interface would be required for recording. Dry, no fx.

[Mark Hammer]

The Dave Hunter Guitar Pickup Handbook has an accompanying soundfile CD with clean uncompressed samples of a wide array of pickups.  Decent book, IMHO (certainly MUCH better than his effect pedal book).  Get yourself a copy and you have a two-fer: useful samples for testing things, and a book chock full of useful info.

[davent]

I see people using the Ditto loop pedal to demo/tweak another pedal.