I think it is supposed to align with the front baffle of the speaker to help with time alignment and phase. If you place it off to the side, it won't function as intended.
But the infrared signal between the "PhotoLink" device and the microphone is traveling at the speed of light. So my thinking is that you should be able to place it anywhere in the room and get the same "time of flight" computation. Unless I am missing something here. Infrared signals are "line of sight" only, so the "PhotoLink" device would only need to be placed so that it could "see" the microphone receptor.
I think PhotoLink works in a similar fashion to the laser measuring devices. So you would need to place it on the baffle front. In REW I manually measure and enter the mic to baffle distance - Photolink just automates that step AFAIK. I personally think Photolink is superfluous, but PE says "The innovative PhotoLink device sets the OmniMic 40K apart from competing measurement systems."
I'd be more interested to see how that mic compares in actual tests to the expensive mics mentioned.
OK, now I think I am beginning to understand how this thing works. The PhotoLink device has two banana jacks on the back which connect to the amplifier that drives the speaker. So the only thing that the PhotoLink box is doing is sending precise information to the microphone as to when the impulse signal began. Once the microphone knows this, the software can caculate TOF. So you should be able to place the PhotoLink box anywhere in the room and it should give you the same TOF calculation.
@4thtry said:
OK, now I think I am beginning to understand how this thing works. The PhotoLink device has two banana jacks on the back which connect to the amplifier that drives the speaker. So the only thing that the PhotoLink box is doing is sending precise information to the microphone as to when the impulse signal began. Once the microphone knows this, the software can caculate TOF. So you should be able to place the PhotoLink box anywhere in the room and it should give you the same TOF calculation.
OK, so the mic is the RECIEVER of the AUDIO signal emanated from the driver(s) and also the START (IR) Signal for the IMPuLSE timing.
@Ed_Perkins said:
I'd be more interested to see how that mic compares in actual tests to the expensive mics mentioned.
Brian Myers said they compare it to the Earthworks stuff, and explained the manufacturers stated the mic only is able to capture to 20k, but they were not thinking about EQing the upper top octave to make it respond to 40k. Once it is known what each mic does individually, they make it fit the curve.
What's the benefit of 40k vs 20k? any practical advantage other than designig a bat cave?
would have preferred a built in laser distance measure in the mic cannon rather than the optical link. Some baffle shapes may not lend very well to it.
@ani_101 said:
What's the benefit of 40k vs 20k? any practical advantage other than designig a bat cave?
would have preferred a built in laser distance measure in the mic cannon rather than the optical link. Some baffle shapes may not lend very well to it.
So you can look at the 28kHz peaking on expensive tweeters.
@ani_101 said:
What's the benefit of 40k vs 20k? any practical advantage ...
If my understanding is correct, measuring HD2 is limited to 10kHz and HD3 to 6.7kHz if you are only measuring the fundamental to 20kHz. Measuring to 40kHz extends those distortion measurements to 20kHz and 13.3kHz.
I think these things are great improvements in the tools available for those who can actually benefit from them but waay overkill for my meager needs.
Very interesting though . . .
@Steve_Lee said:
. . . and how that mic system stacks-up to a two channel/non-USB mic- system from a timing standpoint . . .
Is it dcibel approved?
It should be just as good if not better than my current two channel setup in terms of timing. And more accurate too, because the new mic will be individually calibrated out to 40k. However, my two channel loopback arrangement also calibrates the frequency response of my amplifier. OmniMic 40k does not include the amplifier in the timing loopback. This is why you need to use the new mic with an amplifier that is perfectly flat to 40k.
@Steve_Lee said:
. . . and how that mic system stacks-up to a two channel/non-USB mic- system from a timing standpoint . . .
Is it dcibel approved?
It should be just as good if not better than my current two channel setup in terms of timing. And more accurate too, because the new mic will be individually calibrated out to 40k. However, my two channel loopback arrangement also calibrates the frequency response of my amplifier. OmniMic 40k does not include the amplifier in the timing loopback. This is why you need to use the new mic with an amplifier that is perfectly flat to 40k.
I suppose Dayton has just such an amp for this purpose at another $500+, yes?
This makes sense - the distortion is key for tweeters - would like to see the 2nd and 3rd till 20 Khz. Can this microphone be used with other systems? Any other 40khz calibrated microphones that are system agnostive, XLR or usb? Omni mic is a nice system though i suspect 50% is for the software.
The 500$ DATS has an amp, but i guess it is a single purpose amp - Can it be used for sriving speakers or anything else?
@ani_101 said:
This makes sense - the distortion is key for tweeters - would like to see the 2nd and 3rd till 20 Khz. Can this microphone be used with other systems? Any other 40khz calibrated microphones that are system agnostive, XLR or usb? Omni mic is a nice system though i suspect 50% is for the software.
The 500$ DATS has an amp, but i guess it is a single purpose amp - Can it be used for sriving speakers or anything else?
Will probably be a mono amp, I imagine.
Omnimic will probably work in ARTA if your soundcard supports 96k output.
Just my personal 2 cent opinion, take it or leave it...
I've heard so many fantastic sounding DIY speakers that were designed using only a one channel mic and a WT3 or a few dollar limp jig, then voiced to perfection by a designer with really good ears and intuition. I have zero intentions of taking spinorama measurements and having a program tell we what should sound best. What's next? Just build a measurement jig and import spinorama mesurements and let AI design your speaker for you? Nope! I still trust my ears.
Quoting tktran....
Some oldies but goodies, including the OT19NC, DA25TX and DA32TX, SLS 5” and 6” 830945 and 830946, 830845 12” XXLS 8 ohm fibre cone for sealed boxes, and 12” alu cone XXLS 4 ohm 835017,
I wish the SDF subs were among them. I’d love a second SDF 10 for a DO sub. The 15 was never sold OEM but I’ve been playing with one (OEM version for Genelec) and it plays on the same field as JBL W1500H. IMO a cut above PE’s current 15” woofer lineup.
@charlielaub said:
Still cheaper than Earthworks M30, way cheaper than the M50.
OTOH a lot more expensive than iSEMcon 7150. I also don’t get why they have the complicated box instead of a dual channel sound card.
including Earthworks M23, Line Audio Omni1, Sonarworks Xref20 (now SoundID), miniDSP umik-1 as well as an odd duck- a hand-held dynamic microphone by Sennheiser, and compared them to a 3-piece Brüel & Kjær 4191/2669/2690 setup.
Now if you don't want to read that long thread, who could blame you? The short and dirty summary is-
You can take frequency responses with many mics, and the calibrated ones have the potential to be more accurate at the top and low end. If you want to take accurate distortion measurements, you need a mic with a low noise floor AND a high SPL handling capability, otherwise your driver’s harmonic/IMD is contaminated by the mic. And, of course, one needs to take meticulous care with a having a low noise environment.
There’s lot of may s here. Are these weasel words? No- if your driver/speaker has plenty of distortion, then of course you don’t need a low distortion measurement system.
The price of the Brüel & Kjær is professional instrumentation clas$, $old via bu$iness to bu$iness. There are very good and lower price alternatives from G.R.A.S., Microtech Gefell and ACO that are cheaper (~ half). But they are still 4 figures. And if you want to buy American Made, put your hands deep into your pockets for the model 376A33 from PCB Piezotronics, and you rest easy because it has a Lifetime Warranty.
But the Omnimic40K is a microphone that
offers a calibrated response to 40KHz, AND has lower self noise and higher SPL handling (>145dB for 1% distortion). It’s nearest priced competitor is the Earthworks QTC40 ($999), at twice the cost.
It a MUCH better mic than the one that came with Omnimic 1/2. So I think for people who use, and like Omnimic's workflow, as an upgrade this simply a “no brainer”.
It’s specifications are an order of magnitude better than the mics that come with Audiomatica’s Clio (Mic-02) or are recommended for use with Listen’s Soundcheck (SCM 3/4).
Now people are going to say- well, I don't care about calibrated measurements past 20 KHz. Or I’m fine with my insert favourite/current mic here. Now, some people don't take even measurements, or use any mics when designing speakers. So there's that too, I get it.
But if you want to compare your own measurements to what published by Erinsaudicorner.com, or Hificompass.com, you’ll certainly get a lot closer with the Omnimic40K.
It all depends on the level of accuracy and precision that you want.
@tktran said:
Is it @dcibel approved? I'll leave that to him...
I won't be wasting my time with it. Perhaps like the original Omnimic, it's gear more towards newbies as a plug and play solution. Less versatile than a USB audio Interface and a simple voltage divider dual channel loopback. It uses a weird photo sensor for timing, overly complicating what can be done with a simple wire, and requires proprietary software. I'll be pleasantly surprised if anyone can get that photo sensor to do anything useful in ARTA or REW.
Comments
I think it is supposed to align with the front baffle of the speaker to help with time alignment and phase. If you place it off to the side, it won't function as intended.
But the infrared signal between the "PhotoLink" device and the microphone is traveling at the speed of light. So my thinking is that you should be able to place it anywhere in the room and get the same "time of flight" computation. Unless I am missing something here. Infrared signals are "line of sight" only, so the "PhotoLink" device would only need to be placed so that it could "see" the microphone receptor.
The thing has to measure the TOF between two points in space - one contains the transmitter (mic?) and one is the receiver (PhotoLinkBox?).
I think PhotoLink works in a similar fashion to the laser measuring devices. So you would need to place it on the baffle front. In REW I manually measure and enter the mic to baffle distance - Photolink just automates that step AFAIK. I personally think Photolink is superfluous, but PE says "The innovative PhotoLink device sets the OmniMic 40K apart from competing measurement systems."
I'd be more interested to see how that mic compares in actual tests to the expensive mics mentioned.
No, I think that was "For F Sakes!"
InDIYana Event Website
. . . and how that mic system stacks-up to a two channel/non-USB mic- system from a timing standpoint . . .
Is it dcibel approved?
OK, now I think I am beginning to understand how this thing works. The PhotoLink device has two banana jacks on the back which connect to the amplifier that drives the speaker. So the only thing that the PhotoLink box is doing is sending precise information to the microphone as to when the impulse signal began. Once the microphone knows this, the software can caculate TOF. So you should be able to place the PhotoLink box anywhere in the room and it should give you the same TOF calculation.
OK, so the mic is the RECIEVER of the AUDIO signal emanated from the driver(s) and also the START (IR) Signal for the IMPuLSE timing.
Brian Myers said they compare it to the Earthworks stuff, and explained the manufacturers stated the mic only is able to capture to 20k, but they were not thinking about EQing the upper top octave to make it respond to 40k. Once it is known what each mic does individually, they make it fit the curve.
InDIYana Event Website
What's the benefit of 40k vs 20k? any practical advantage other than designig a bat cave?
would have preferred a built in laser distance measure in the mic cannon rather than the optical link. Some baffle shapes may not lend very well to it.
. . . where is the acoustic center? . . .
Noone really knows. All you need to know the relative phase difference between your drivers.
So you can look at the 28kHz peaking on expensive tweeters.
. . . Still need a face/palm smiley here . . .
If my understanding is correct, measuring HD2 is limited to 10kHz and HD3 to 6.7kHz if you are only measuring the fundamental to 20kHz. Measuring to 40kHz extends those distortion measurements to 20kHz and 13.3kHz.
And distortion to 20k.
InDIYana Event Website
I think these things are great improvements in the tools available for those who can actually benefit from them but waay overkill for my meager needs.
Very interesting though . . .
It should be just as good if not better than my current two channel setup in terms of timing. And more accurate too, because the new mic will be individually calibrated out to 40k. However, my two channel loopback arrangement also calibrates the frequency response of my amplifier. OmniMic 40k does not include the amplifier in the timing loopback. This is why you need to use the new mic with an amplifier that is perfectly flat to 40k.
I suppose Dayton has just such an amp for this purpose at another $500+, yes?
Most amy decent amp will be linear out to 40k. Class D might not be, however.
This makes sense - the distortion is key for tweeters - would like to see the 2nd and 3rd till 20 Khz. Can this microphone be used with other systems? Any other 40khz calibrated microphones that are system agnostive, XLR or usb? Omni mic is a nice system though i suspect 50% is for the software.
The 500$ DATS has an amp, but i guess it is a single purpose amp - Can it be used for sriving speakers or anything else?
Will probably be a mono amp, I imagine.
Omnimic will probably work in ARTA if your soundcard supports 96k output.
The DATS-LA amp is integrated into the chassis for that purpose, and is not separate nor does it have discrete inputs last I knew.
InDIYana Event Website
Earthworks M50...$1,300
Just my personal 2 cent opinion, take it or leave it...
I've heard so many fantastic sounding DIY speakers that were designed using only a one channel mic and a WT3 or a few dollar limp jig, then voiced to perfection by a designer with really good ears and intuition. I have zero intentions of taking spinorama measurements and having a program tell we what should sound best. What's next? Just build a measurement jig and import spinorama mesurements and let AI design your speaker for you? Nope! I still trust my ears.
I wish the SDF subs were among them. I’d love a second SDF 10 for a DO sub. The 15 was never sold OEM but I’ve been playing with one (OEM version for Genelec) and it plays on the same field as JBL W1500H. IMO a cut above PE’s current 15” woofer lineup.
OTOH a lot more expensive than iSEMcon 7150. I also don’t get why they have the complicated box instead of a dual channel sound card.
Good on Bill Waslo and Parts Express for finally getting the Omnimic 40K released.
I have surveyed multiple microphones that may be suitable for frequency response and distortion measurements here:
https://diyaudio.com/community/threads/in-search-of-low-distortion-omnidirectional-microphones-for-diyers.412011/
including Earthworks M23, Line Audio Omni1, Sonarworks Xref20 (now SoundID), miniDSP umik-1 as well as an odd duck- a hand-held dynamic microphone by Sennheiser, and compared them to a 3-piece Brüel & Kjær 4191/2669/2690 setup.
Now if you don't want to read that long thread, who could blame you? The short and dirty summary is-
You can take frequency responses with many mics, and the calibrated ones have the potential to be more accurate at the top and low end. If you want to take accurate distortion measurements, you need a mic with a low noise floor AND a high SPL handling capability, otherwise your driver’s harmonic/IMD is contaminated by the mic. And, of course, one needs to take meticulous care with a having a low noise environment.
There’s lot of may s here. Are these weasel words? No- if your driver/speaker has plenty of distortion, then of course you don’t need a low distortion measurement system.
The price of the Brüel & Kjær is professional instrumentation clas$, $old via bu$iness to bu$iness. There are very good and lower price alternatives from G.R.A.S., Microtech Gefell and ACO that are cheaper (~ half). But they are still 4 figures. And if you want to buy American Made, put your hands deep into your pockets for the model 376A33 from PCB Piezotronics, and you rest easy because it has a Lifetime Warranty.
But the Omnimic40K is a microphone that
offers a calibrated response to 40KHz, AND has lower self noise and higher SPL handling (>145dB for 1% distortion). It’s nearest priced competitor is the Earthworks QTC40 ($999), at twice the cost.
It a MUCH better mic than the one that came with Omnimic 1/2. So I think for people who use, and like Omnimic's workflow, as an upgrade this simply a “no brainer”.
It’s specifications are an order of magnitude better than the mics that come with Audiomatica’s Clio (Mic-02) or are recommended for use with Listen’s Soundcheck (SCM 3/4).
Now people are going to say- well, I don't care about calibrated measurements past 20 KHz. Or I’m fine with my insert favourite/current mic here. Now, some people don't take even measurements, or use any mics when designing speakers. So there's that too, I get it.
But if you want to compare your own measurements to what published by Erinsaudicorner.com, or Hificompass.com, you’ll certainly get a lot closer with the Omnimic40K.
It all depends on the level of accuracy and precision that you want.
Is it @dcibel approved? I'll leave that to him...
Thanks again @tktran . You always have great posts!
I won't be wasting my time with it. Perhaps like the original Omnimic, it's gear more towards newbies as a plug and play solution. Less versatile than a USB audio Interface and a simple voltage divider dual channel loopback. It uses a weird photo sensor for timing, overly complicating what can be done with a simple wire, and requires proprietary software. I'll be pleasantly surprised if anyone can get that photo sensor to do anything useful in ARTA or REW.
Is this really too complicated for people?
It isn't as sexy as an optical device without all that spaghetti . . .