Official Luthiers Forum!

Some time back I picked up Gillet Gore. Phew. Super informative. SUPER duper technical in that first book. Is it making me a better builder...? Probably

However a lot of it hinges on being able to measure the resonant frequencies, and I just can not find where any suggestions to applications or programs are made by which to do so. Now.... I should know where it is... yes. But most of that book is written in another language ha... at least for this simpleton.

What hardware do you guys use? Any help is appreciated.


Sent from my iPhone using Tapatalk

Is this helpful?

viewtopic.php?f=10101&t=51389&p=676685&hilit=Gore+software#p676685

I’ll check it out. Thanks:)


Sent from my iPhone using Tapatalk

Check this out from Trevor Gore:

https://goreguitars.com.au/attachments/ ... 018_A4.pdf

On your question about hardware:

I just multipurpose my audio recording hardware, which is overkill for the task, but it keeps me from having to buy anything new.

If you don't own audio recording hardware, you can get by with a USB microphone plugged straight into your computer.

If you do own audio recording hardware (an interface, some mics, etc.), just pick a good, neutral condenser mic, plug it into the interface, and then it's a software setup task.

I found that Audacity is super easy to set up, but it does not measure precisely enough for Trevor Gore's preference. Visual Analyzer (the specific version he prefers) is better, but there is more to setting it up.

These days I don’t do much home recording anymore. I do have access to sound equipment that would fit the bill, I believe. Thanks for the insight


Sent from my iPhone using Tapatalk

With a quality external mic I wonder if this would fit the bill



Sent from my iPhone using Tapatalk

Nope it doesn’t:)


Sent from my iPhone using Tapatalk

I think it is worthwhile to just download the software Trevor Gore recommends in that set of instructions to which I linked earlier, and then follow his detailed guidance (same document) on how to set it up. He has already done all the hard work; might as well take advantage of his graciousness in sharing it.

I’ve been using Trevor’s approach since shortly after the book was first released. I struggled a bit to create a spreadsheet to perform all the calculations in single row in the same sheet as I record the data for each sample, but now I just copy and paste additional rows in my sheet.

For microphone, I use a Snowflake USB mic — not expensive and gets the job done. I use a drafting eraser impaled on an electrician’s screwdriver as a mallet. For software I use Peterson’s Strobosoft PC version. It includes tap analysis to average several taps, tossing out any outliers. Generating the long and twist mode resonances is always easy. The software doesn’t always identify the correct resonance for cross grain automatically with its tap function, but the correct peak is always obvious in the oscilloscope view (similar to Visual Analyser). I like the Peterson products and use them throughout my shop.



Sent from my iPad using Tapatalk

If I remember correctly, it isn’t available on Mac.

As far as mics go, Dayton Audio offers an inexpensive USB mic made specifically for measurement applications. Most mics are slightly weighted, but measurement mics are designed to give a flat response. I use one when measuring EQ response in my car since each speaker/driver is independently EQ’d.

https://www.parts-express.com/dayton-au ... FxEALw_wcB


Sent from my iPhone using Tapatalk

Robbie O'Brien has just released a video class taught by Trevor that details how to set up VA, as well as how to take measurements and do a lot of other stuff from his modal tuning class.

_________________
It will probably be alright.

How flat of a frequency response does this method require from the microphone itself? Is the Snowflake flat enough in the right places? Looks like you wouldn't want to use it in cardioid:

http://recordinghacks.com/microphones/B ... s/Snowball

Flat enough? I should defer to my nephew who is a professional sound engineer / producer, and he sure knows his microphones, but for this application we’re merely trying to identify strong resonant frequencies. I don’t see that flat response is necessarily required.


Sent from my iPad using Tapatalk

I use a drum mike to make seeing the lowest frequencies you're looking for easier.

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I somehow missed James' post up above, but I think he's right in that you should be using a "measurement microphone" with a flat frequency response across the board, unless you knowingly compensate for your microphone's frequency response graph (e.g. the peaks and valleys at certain frequencies). Could someone please correct me if I'm wrong? Maybe this does not apply to this method of capturing frequency responses.

A friend of mine has written an Android app that includes a spectrum analyzer, as well as signal generator, and a bunch of other stuff. It's free, too! It's called 'Luthier Lab'. A search should turn it up.

I'm pretty sure the frequency response is irrelevant. Those graphs measure the amplitude the mics pickup against a know signal output. That's not the same as not being able to accurately identify what that frequency is. Make sense?

Ed, click on that O'Brien link above. Under Chapter 2 it says "Lesson 1: Capturing a frequency response curve". This is what has me confused and leads me to believe one should be using a dead flat mic. Again, I'm probably wrong about this.

All I can see is the words, there's no vid.

But I believe it refers to capturing a response curve of a guitar, not a mic.

As long as the mic captures the right freq, the amplitude doesn't really matter.

Mic response charts show you the inaccuracy of the amplitude recorded by the mic. So it shows you if your mic has a 4K hump, it might make a nice voiceover mic etc...

If i recall from the books, Trevor's just using a voice mic, something along the lines of shure or something. Pretty sure you don't need a flat response as when looking at frequency, not amplitude.

_________________
Jim Watts
http://jameswattsguitars.com

IIRC, it's just an SM57...

That actually makes a lot of sense. Noted. We're looking for what the frequency is, not how loud it is.

That was exactly my point.


Sent from my iPad using Tapatalk