The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Acoustic Amplification

Reply
 
Thread Tools
  #1  
Old 11-20-2020, 03:51 PM
schinckley schinckley is offline
Registered User
 
Join Date: Oct 2019
Posts: 28
Default Baggs Voiceprint & using the iPhone Mic for IR creation

There have been some comments in other threads about using the iPhone's mic for IR creation, but since the microphone is such a big part of the equation in IR, I thought it deserved its own thread.

I am a previous Tonedexter owner and future Voiceprint DI owner (should arrive next week). I have also messed around with Cuki's IR software. I'm no expert, but I had some thoughts about the differences between how most previous IR's use microphones and how Baggs may be using the iPhone mic and wanted to get a discussion going about it. I may be totally wrong in my understanding and conjectures, but humor me and correct my mistakes so we can all learn.

While most IR's accept (in fact, welcome) the coloration of the microphone as part of the IR, Baggs may be trying to remove coloration by using the iPhone mic as a measurement tool rather than a "sound capture device." An analogy may be the difference between using a KM184 and an RTA mic. Each are used for different purposes, and processed differently. For example, when you want to "capture" the sound of a room in a recording, you may choose specific mics with specific polar patterns placed in specific locations (think of capturing the "room sound" when recording drums). If you want to "measure" the response of the room, you would use an RTA measurement mic, a frequency sweep, and some software.

Some people have questioned the ability of the iPhone mic to adequately "capture" the sound of the guitar. If the goal was to capture the sound of the guitar, then there are much better mics out there. But if Baggs was looking to "measure" the sound of the guitar, using the iPhone mic makes a lot of sense because its characteristics can be measured and accounted for when creating a Voiceprint.

Previous IR creators, like Tonedexter, "capture" the response of the guitar as colored by the microphone used. In fact, being able to use different mics (to say nothing of mic placement) is a feature of previous IR’s. The resulting IR reflected the characteristics of the microphone's response.

In contrast, in one of the YouTube videos from NAMM, Lloyd Baggs says they are using the iPhone mic more as a “quantitative” device rather than a “qualitative” device. I gather this to mean they are using it more like a measurement mic one would use for RTA to measure the response of a room. RTA mics are typically designed with a flat frequency response. They want to avoid coloring the sound. Some RTA mic manufacturers include the specific frequency response of the mic that comes in the box. I've seen that some Sonarwerks software includes a place to enter the serial number of your specific mic, which has it's own sonic signature (within manufacturing specs), and can "delete" that signature from measurements.

I’m sure that Baggs did audio testing of the iPhone mic of various models to determine its characteristics. The AcousticLive app knows which device it is installed on and hence which mic hardware is present and can use that data in the creation of the Voiceprint. It can "delete" the sonic signature of the mic from the completed IR.

Therefore, using a different mic, like some that plug into the iPhone, may not actually create a “better” Voiceprint because it is not what the software is expecting (indeed, not even how the software was intended to work). In fact, it might be “worse.” How this works in practice, of course, remains to be seen, and maybe we’ll get some experimenter’s who upload samples.

As a side note, if this is, in fact, how Baggs is using the iPhone mic, it might be one reason that there is not an Android version of the app (yet). iPhone, as a product line, has a relatively small number of microphones that the Voiceprint software would need to “know” about. The Android hardware marketplace is much more diverse and would just require more time to test the hardware and include the results in the AcousticLive app for Voiceprint creation. (This is assuming they are using the mic as a measurement device rather than a "sound capture" device.)

I would love to hear thoughts from others on this, especially our resident IR experts, Cuki and Jon. What would be the advantages/disadvantages of taking a “measurement microphone” approach to creating IR’s? Or, put differently, if you are given the the data of the particular mic, can you use that information to your advantage in creating an IR?
Reply With Quote
  #2  
Old 11-20-2020, 04:50 PM
sdelsolray sdelsolray is offline
Charter Member
 
Join Date: May 2004
Location: Portland, OR
Posts: 6,951
Default

The iPhone internal mic is not a measurement microphone in the first place. In addition, the microphone signal is tweaked by Apple to serve its primary purpose - to capture the human voice at close range.

I suspect adding a flat response mic to the iPhone will get closer to a measurement microphone and likely improve the subsequently generated IRs.
Reply With Quote
  #3  
Old 11-20-2020, 05:40 PM
loco gringo loco gringo is offline
Registered User
 
Join Date: Dec 2008
Posts: 930
Default

I think James May has mentioned that good results have been had on the ToneDexter using actual measurement mics, like the ones you can get for $60.00 on Amazon, Dayton or Behringer brand, maybe. I actually thought about ordering one to play with, but I haven't done it, mainly because the mic I have works good.

I have wondered if Baggs has eq'd the i phone mic to be flat or if they are using it as is.

Last edited by loco gringo; 11-20-2020 at 05:47 PM.
Reply With Quote
  #4  
Old 11-20-2020, 05:41 PM
Doug Young's Avatar
Doug Young Doug Young is offline
Charter Member
 
Join Date: Apr 2005
Location: Mountain View, CA
Posts: 9,879
Default

I think people worry too much about the mic, whether it's the Baggs pedal or ToneDexter. The cheapest mic you can find sounds better than the best pickup you can buy, and should be adequate for training. Although different mics may give different results, mic placement plays a far bigger role, just as in recording. Baggs may be calibrating for the phone mic, or may not, hard to know. If I was developing this device/app, I'd certainly give that a try, especially if I was going to roll it out on multiple devices. But it might or might not really matter.

Nothing wrong with experimenting, tho. Once you get one, try it with various mics and see what you like. My guess is there will be some differences, but which is "better" will be a matter of personal taste. You could even pull sound out of your iphone and use the phone mic to train tonedexter and see how that works, if you're into experimenting.
Reply With Quote
  #5  
Old 11-20-2020, 06:19 PM
schinckley schinckley is offline
Registered User
 
Join Date: Oct 2019
Posts: 28
Default

Quote:
Originally Posted by Doug Young View Post
You could even pull sound out of your iphone and use the phone mic to train tonedexter and see how that works, if you're into experimenting.
That would be a really interesting A/B, if I still had the Tonedexter.
Reply With Quote
  #6  
Old 11-20-2020, 06:31 PM
lkingston lkingston is offline
Registered User
 
Join Date: Dec 2009
Location: Asheville North Carolina
Posts: 3,231
Default

One thing about phone mics is that many sound people now use RTA (Real Time Analysis) apps instead of hardware RTA devices when setting EQs for PA systems. What most of us find is that the apps actually work well from the low mids on up. For the low frequencies, hardware RTA devices work better.

This is interesting because the frequencies that acoustic guitars produce are well within the range where phone mics work well for RTA of a room.

Keep in mind that phone mics are omnidirectional, and omni mics typically have pretty flat frequency responses, even in the budget range.

My guess is that LR Baggs studied this in depth and did a lot of experimentation before deciding on this as a solution.

The other thing that I’d like to add here is that the LR Baggs could likely be used with USB audio interfaces or mics if someone really wanted to experiment with different external mics instead of the built in phone mic.
Reply With Quote
  #7  
Old 11-20-2020, 06:36 PM
schinckley schinckley is offline
Registered User
 
Join Date: Oct 2019
Posts: 28
Default

Quote:
Originally Posted by sdelsolray View Post
The iPhone internal mic is not a measurement microphone in the first place. In addition, the microphone signal is tweaked by Apple to serve its primary purpose - to capture the human voice at close range.

I suspect adding a flat response mic to the iPhone will get closer to a measurement microphone and likely improve the subsequently generated IRs.
Whatever type of mic it is, and however Apple has tweaked it, it is at least a known quantity and can be accounted for in the software generation of the IR. It seems to me to be theoretically possible to use (almost) any microphone as a measurement microphone if one knows that mic's characteristics and could account for it in evaluating the mic's output signal. I would be shocked if Baggs did not take measurements of the iPhone mic's response as part of their R&D and only slightly less shocked if they don't use that data in some way in the software. If that's the case, then using a different mic would at a minimum give you a different sound from the IR. Whether it's an improvement would be in the ear of the beholder.
Reply With Quote
  #8  
Old 11-20-2020, 07:00 PM
James May's Avatar
James May James May is offline
AGF Sponsor
 
Join Date: Dec 2015
Location: Nevada City, CA
Posts: 711
Default

Quote:
Originally Posted by loco gringo View Post
I think James May has mentioned that good results have been had on the ToneDexter using actual measurement mics, like the ones you can get for $60.00 on Amazon, Dayton or Behringer brand, maybe. I actually thought about ordering one to play with, but I haven't done it, mainly because the mic I have works good....
Yes indeed they do. They main difference is that they are omni and people generally use cardioids for micing a guitar. If both mic types are flat, you'll get about the same result, save for a bit of extra ambience in the WaveMap created with the omni. And BTW, a mic's self noise is totally irrelevant for WaveMap creation. As an example, we have trained WaveMaps on the show floor at NAMM and gotten stellar results.

Quote:
Originally Posted by Doug Young View Post
I think people worry too much about the mic, whether it's the Baggs pedal or ToneDexter. The cheapest mic you can find sounds better than the best pickup you can buy, and should be adequate for training. Although different mics may give different results, mic placement plays a far bigger role, just as in recording. ...
Well said, and for the most part spot on. I would qualify this a little by adding that once you get a "better than the best" pickup sound with any old mic, you'll probably be inclined to find a mic that has a flattish response to refine your WaveMap for better suitability for live gigging. I don't know why exactly, but mics with colored responses tend to work against translation into live sound reinforcement. Not all, but many, and let's not forget how instrument depended this is.

Quote:
Originally Posted by schinckley View Post
That would be a really interesting A/B, if I still had the Tonedexter.
We'd be happy to sell you another . And yes, I suspect in iPhone mic would probably work pretty well feeding ToneDexter, subject to my comments above. The mic is not really the weak link in the IR creation process. We're not going to tell anyone what the weak link really is, however .
__________________
James May
Audio Sprockets
maker of ToneDexter
James May Engineering
maker of the Ultra Tonic Pickup
Reply With Quote
  #9  
Old 11-20-2020, 07:07 PM
schinckley schinckley is offline
Registered User
 
Join Date: Oct 2019
Posts: 28
Default

Quote:
Originally Posted by Doug Young View Post
try it with various mics and see what you like.
This is indicative of how we are used to talking about IR, and something I've found frustrating about it in use. And I think Baggs is trying to remove this variable from the equation. If I'm right about this, then it's really different than how other IR's are produced and is worth examining. It makes the capture so much simpler and removes a lot of variables from the equation.

One of the things that's attractive to me about the Voiceprint is that it removes any decisions about mic and mic placement. It was one of the difficulties for me with the Tonedexter - I made many Wavemaps which all sounded different and none of which I liked. While I can see that some may like this ability, and may know more about mics and placement, and have better acoustically treated rooms than I, and own more mics, and know people that own more/better mics, but as a lay person and noob at acoustic amplification, I just couldn't get it to work for me. Or I just didn't like the sound. Or perhaps I didn't know how good I had it. At any rate, I sold the pedal.

My hope with the Baggs Voiceprint is that it will give me a sound I like with (relative) ease. At the very least, it will eliminate the "If I only had X mic, I wonder would that would sound like....." I either like the IR, or I don't.

In the end, I don't think one way is "better" than the other. I definitely think there is room in the market for a "Tonedexter + mic of your choice" option and a "use the app" option for IR products.
Reply With Quote
  #10  
Old 11-20-2020, 08:17 PM
martingitdave martingitdave is offline
Registered User
 
Join Date: Feb 2014
Location: Chicago
Posts: 11,287
Default

Quote:
Originally Posted by James May View Post
We're not going to tell anyone what the weak link really is, however .
Our playing?
__________________
"Lift your head and smile at trouble. You'll find happiness someday."
Reply With Quote
  #11  
Old 11-20-2020, 11:16 PM
James May's Avatar
James May James May is offline
AGF Sponsor
 
Join Date: Dec 2015
Location: Nevada City, CA
Posts: 711
Default

Quote:
Originally Posted by martingitdave View Post
Our playing?
Nah! For training, playing ability doesn't matter. My comment was aimed at the ever increasing cadre of acoustic IR algorithm developers.
__________________
James May
Audio Sprockets
maker of ToneDexter
James May Engineering
maker of the Ultra Tonic Pickup
Reply With Quote
  #12  
Old 11-21-2020, 05:47 AM
jonfields45 jonfields45 is offline
Registered User
 
Join Date: Jun 2011
Location: Allentown, PA
Posts: 4,598
Default

Quote:
Originally Posted by James May View Post
Nah! For training, playing ability doesn't matter. My comment was aimed at the ever increasing cadre of acoustic IR algorithm developers.
If you are curious, my algorithm does a competitive job and the heavily commented code and a detailed code description are there for your reading pleasure.

The primary algotithmic limitations are the usual problems of digital audio...various quantization noises (time, amplitude, frequency) exasperated by low SNR at some frequencies that are then magnified by taking a ratio of two different processed samples (mic & pup).

The primary assumption problem is a single IR is adequate for every possible note played every possible way on your guitar. This is certainly not true for a magnetic pickup but seems quite reasonable for most other pickups as evidenced by the excellent results of ToneDexter (and presumably the Baggs and Nux products).

A Line6 Variax with an IR per string would be the next step up but likely only justified trying to make their solid body electric with steel strings and a plain G sound like a decent acoustic.

In my experience, experimenting with mic placement is more rewarding than mic selection. I'm not sure that extends to the inexpensive MEMS mic in a cell phone, but it might.

Regrettably, the most impressive IR results (staggering improvement) are with relatively inexpensive pickups, which are factory stock on even high end Gibsons for example, but not the stock and trade of the typical AGF reader.
__________________
jf45ir Free DIY Acoustic Guitar IR Generator
.wav file, 30 seconds, pickup left, mic right, open position strumming best...send to direct email below
I'll send you 100/0, 75/25, 50/50 & 0/100 IR/Bypass IRs
IR Demo, read the description too: https://youtu.be/SELEE4yugjE
My duo's website and my email... [email protected]

Jon Fields

Last edited by jonfields45; 11-21-2020 at 09:06 AM.
Reply With Quote
  #13  
Old 11-21-2020, 07:36 AM
schinckley schinckley is offline
Registered User
 
Join Date: Oct 2019
Posts: 28
Default

Quote:
Originally Posted by jonfields45 View Post
the most impressive IR results are with relatively inexpensive pickups,
I'm curious, Jon, do you mean the most impressive improvements come from inexpensive pickups, or the absolute best results come from inexpensive pickups?

Interesting to hear from IR creators that the mic is not the most important part when programming an algorithm. From a user's perspective, "the mic", meaning mic choice and placement, is absolutely the most influential factor when "training" the IR, at least from my experience playing with Tonedexter and Cuki's generator.

Jon, do you have a link to your code and commentary? I don't know anything about software coding (perhaps the reason I may sound like an idiot when I talk about IR), but I'd be interested to read the commentary. Do you describe what the code is doing?
Reply With Quote
  #14  
Old 11-21-2020, 08:29 AM
jonfields45 jonfields45 is offline
Registered User
 
Join Date: Jun 2011
Location: Allentown, PA
Posts: 4,598
Default

Quote:
Originally Posted by schinckley View Post
I'm curious, Jon, do you mean the most impressive improvements come from inexpensive pickups, or the absolute best results come from inexpensive pickups?
--- Improvement: ToneDexter and an inexpensive Element UST to my ear is truly excellent.
Quote:
Originally Posted by schinckley View Post

Interesting to hear from IR creators that the mic is not the most important part when programming an algorithm. From a user's perspective, "the mic", meaning mic choice and placement, is absolutely the most influential factor when "training" the IR, at least from my experience playing with Tonedexter and Cuki's generator.
--- I imagine a more detailed listener than me might find mic selection a worthy but expensive path of experimentation.
Quote:
Originally Posted by schinckley View Post

Jon, do you have a link to your code and commentary? I don't know anything about software coding (perhaps the reason I may sound like an idiot when I talk about IR), but I'd be interested to read the commentary. Do you describe what the code is doing?
--- Just click the link in my signature. After the usage instructions is an explanation of how it works followed by the commented Matlab/Octave source code.
__________________
jf45ir Free DIY Acoustic Guitar IR Generator
.wav file, 30 seconds, pickup left, mic right, open position strumming best...send to direct email below
I'll send you 100/0, 75/25, 50/50 & 0/100 IR/Bypass IRs
IR Demo, read the description too: https://youtu.be/SELEE4yugjE
My duo's website and my email... [email protected]

Jon Fields

Last edited by jonfields45; 11-21-2020 at 06:13 PM.
Reply With Quote
  #15  
Old 11-21-2020, 03:33 PM
89bruin 89bruin is offline
Registered User
 
Join Date: Apr 2018
Location: Tidewater, VA
Posts: 380
Default

Disclaimers first: 1) I’m a fan of Baggs products 2) I’m not in the market for either a Voiceprint or a Tonedexter since the pickups in my primary instruments are Lyrics and I’m satisfied with them for my purposes. That said, I would be wary of shelling out that amount of cash for any device that’s tied so intricately to a phone or OS. What happens when Apple decides to go a different route. Consider how may devices are now obsolete or will require an adapter or other work-around now that Apple is abandoning the lightning connector for iOS devices, for example. That seems to be a liability without the ability to use a standard mic.
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Acoustic Amplification

Thread Tools





All times are GMT -6. The time now is 02:08 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ©2000 - 2022, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=