Can I create an FRD file using Omnimic by...

[tomzarbo]

just pointing the mic at the center of the (in this case 2" dome midrange) driver as close as possible with the driver laying face up on a table? ...or something similar?

I'm reading here and there for the probably obvious answer and I can't really find it. I know I can't do that with a woofer, but is it okay to do with a midrange driver with a sealed back with no pole venting?

This is to generate a working FRD file to import into WinPCD to model a crossover by the way. Figured out how to generate a zma file using my woofer tester 3 just this morning... so the light bulbs are starting to go off! I'm gonna' figure this stuff out if it kills me dadgummit!

Thanks,
TomZ

[[email protected]]

Re: Can I create an FRD file using Omnimic by...

Tom, In my opinion,
You need to measure the TS with the WT3 to determine the volume for your open back drivers.
Build the Box and mount the drivers.
Measure Inpedence with the wt3 on all the drivers "in box".
Then measure each driver at a couple feet on the tweeter axis. (Read Jeff B's paper on finding acoustic centers)
Export each file as .FRD.
You can run all of them trough Response Modeler, Adjust for BSC and extract Minimum Phase. Rename them as frd-modified and zma-modified.
Import them all into PCD
Set all the offsets that you got during you first measuring session (jeffs paper)
Then you can set targets and go to town.

All six files can be

[tomzarbo]

Re: Can I create an FRD file using Omnimic by...

Arlis,

I asked a similar question a few weeks ago referring to getting FRD and ZMA files, and you said:

"I measure ts to determine the best volume, build the enclosure, then measure in box to get frd and actual zma."

I thank you for being patient with me, I must seem like a little bit of a knucklehead understanding this stuff.

But I guess what I'm getting at is how do you know if your selected drivers will work together well enough to even purchase them and put them in a box? Without modeling things how can you know if your selected drivers have a good chance of working the way you intended them to.... or is this why so many here have so many extra drivers?

I will get a box together asap as soon as the drivers arrive and try to follow your steps.

Thanks again for bearing with me,
TomZ

PS was there anything else you meant to say.... "all six files can be..." ?

[Chris Roemer]

Re: Can I create an FRD file using Omnimic by...

Most guys will scour the net until they find SOME kind of freq. and imp. plots, then trace them with something like "SPLTrace". Worst case for a Z file would be to create one from WinISD data.

[tomzarbo]

Re: Can I create an FRD file using Omnimic by...

Most guys will scour the net until they find SOME kind of freq. and imp. plots, then trace them with something like "SPLTrace". Worst case for a Z file would be to create one from WinISD data.

I have the drivers, or I will have them by tomorrow, I can whip up a volume box to test from, but the actual box will be quite complex and will take me a few months to finish. I guess I should get the volume as close as possible to what the actual woofer box will be with port, and then make a baffle of the same dimension and mount the tweet/mid. The midrange is a sealed back unit, so no enclosure needed there.

Thing is, there's gonna' be curves pretty much everywhere on this cabinet except for the front baffle, and it will take me some time to get this built. There's a few things that I'm not sure how I will even do, but that's the challenge that I love about this process.

This crossover stuff is hard to get, but I really, really respect and admire you guys who have mastered this process and really understand it. Prepare to have an additional member added to your ranks eventually though, I don't give up. ;)

TomZ

[[email protected]]

Re: Can I create an FRD file using Omnimic by...

Yep, that's the way it is Tom. You can do all kinds of things but eventually you must measure the drivers in their home. This should include where they will live.
Concerning mating drivers;
look for drivers that have smooth fr above(in the case of woofer)where you intend to cross it. and a tweeter with smooth fr below where you intend to cross them.
With this build, I would just estimate the acoustic offsets. You can learn Jeffs method later.
Please don't apologize for not knowing this stuff. I suspect you will surpass my knowledge in no time at all.
When you have your cabs built and are ready to measure I'll be more then happy to get on the phone with you, we can do it together if it helps. same, when you are ready to run the files through RM and PCD.
Lots of folks helped me and I'm more then happy to pay it forward.

[tomzarbo]

Re: Can I create an FRD file using Omnimic by...

Yep, that's the way it is Tom. You can do all kinds of things but eventually you must measure the drivers in their home. This should include where they will live.
Concerning mating drivers;
look for drivers that have smooth fr above(in the case of woofer)where you intend to cross it. and a tweeter with smooth fr below where you intend to cross them.
With this build, I would just estimate the acoustic offsets. You can learn Jeffs method later.
Please don't apologize for not knowing this stuff. I suspect you will surpass my knowledge in no time at all.
When you have your cabs built and are ready to measure I'll be more then happy to get on the phone with you, we can do it together if it helps. same, when you are ready to run the files through RM and PCD.
Lots of folks helped me and I'm more then happy to pay it forward.

Arlis,

I can't thank you enough for your offer of help. I will get the cabs built and go from there. I intend to do my due diligence to learn from the material which is already out there, and has been clearly presented -- but I usually get stuck a few times, my brain works kind of funky sometimes...I will likely take you up on your offer at some point.

Seeing the announcement today that registration is open for this year's MAF is getting my blood flowing to get started making some sawdust.

Thanks again for the kind offer.

TomZ

[[email protected]]

Re: Can I create an FRD file using Omnimic by...

Wolf has some stuff in his blog as well.

[howard]

Re: Can I create an FRD file using Omnimic by...

Arlis,
If you measure your drivers in their cabinet do you still need to use the response modeler, adjust for BSC and extract minimum phase?
Howard

[[email protected]]

Re: Can I create an FRD file using Omnimic by...

The BSLoss should be contained in the measurement. That is why you should measure where they will live. I find that the measured phase can often be very messy. When I extract min phase, the area around the cross stays about the same, but is cleaner looking.
When I get around to my next build, I'll use 'fr blender' and extract the phase with it.
JeffB has a nice white paper on its use.
here http://audio.claub.net/software.html

[howard]

Re: Can I create an FRD file using Omnimic by...

Thanks for the reply. I find that if I get too many steps I get lost. I have been trying to get this for about 10 years and I am closer but still not there yet.
Howard

[[email protected]]

Re: Can I create an FRD file using Omnimic by...

Same here Howard. I find it very important to name all files so you know their stage.
Measured frd=RAW. Min Phase = frd-extracted. Ran through the Blender= frd-blended, etc. That way you import the right ones into PCD.

[duanebro]

Re: Can I create an FRD file using Omnimic by...

Same here Howard. I find it very important to name all files so you know their stage.
Measured frd=RAW. Min Phase = frd-extracted. Ran through the Blender= frd-blended, etc. That way you import the right ones into PCD.

Very true, more so when you are coming back to try again after a few months off...

[flisterseven]

FRD" type text files as generated by OmniMic or other programs. These files can also be easily created using any text editor such as Windows' "Notepad", or a spreadsheet program. avast driver jiofi.local.html

[Rao Shaheryar]

I read your question and then I find solution the solution I find which is also describe in this forum I supported this answer
"FRD" type text files as generated by OmniMic or other programs. These files can also be easily created using any text editor such as Windows' "Notepad", or a spreadsheet program." Thank You!!