A HOLM starter guide

[mhtplsh]

i wish to use Holm for testing passive crossover.
I am planning to use the setup as per the file attached.
Guide me to calibrate & setup the so to get flat response

[JoshK]

Re: A HOLM starter guide

I'm doing the loopback calibration. Does this look right?

[JoshK]

Re: A HOLM starter guide

Zvuchniak, did you ever figure yours out? My IR doesn't look right either. I am using a Focusrite Scarlett 6i6.

[JoshK]

Re: A HOLM starter guide

Hey, I'm tuxedocivic from AVSforum. I think I might be who sent you over here.

I've had this exact problem before with a laptop. I've never really put my finger on it, but I believe it's the mic in the computer just won't go away and takes the measurement. These mics often have a 5khz low pass, and that looks to be the case here also. They also have a messy impulse response and give that exact output. Same with my webcam on my desktop. Try finding that thing and turn it off. I've become very frustrated with them at times. They just won't go away, even when I disable them it seems.
.

Voila...I think I found my problem! I spent 4 hours yesterday trying to figure out what the hell was going on with my calibration and why the measurements look so bad. Also why I kept getting feedback when I would turn the mic up (only mic to soundcard and soundcard to amp to speaker). Maybe, just maybe that is it?!

[Zvuchniak]

Re: A HOLM starter guide

Thanks. I'm gonna need it :D

DE250 was similar to measurements that others made. I'm not saying that i didn't get good measurement. My whole problem with this is ugly impulse response. I want to make it right because i know it can be made that way. I don't think that because of that FR is not as it should be.

Zilchs measurements was 1/6 smoothed. When it is smoothed that way it looks similar. Measurement signal settings has field that you put frquency from where you want to start measuring. Mine is set 60Hz. I did it with no perticular reason.

[ryanbouma]

Re: A HOLM starter guide

With help of NEO Dan and Pano i fixed it. It looks like this now:

[ATTACH=CONFIG]27192[/ATTACH]

But impulse is still screwed up.

Ah, those guys know what they're doing

Still looks wrong though. Shouldn't fall that rapidly below 80hz. Those sound cards are better than that. Unless you had a 80hz high pass filter turned on.

Hmm, still a bad IR huh... Not sure what to say at this point then. How did you get good results measuring the DE250 but not this Deltalite? If you is good and everything stays the same, then the other should be good also. I doubt that woofer has that much ringing though. Not sure...

Good luck :(

[Zvuchniak]

Re: A HOLM starter guide

EDIT - can you show a smoothed (no gating) response? And what driver is this? Is the FR known? I still feel this isn't a measurement from you mic.

Sorry now. I didn't see when you edited your post.

Midbas is Eminence Deltalite II 2512 and ungated smoothed response 1/12 looks like this:



Bare in mind that screenshots from above are in 2dB increments. Mic is Ok because i measured B&C DE250 and it was similar to factory, Zilch and BWaslo measurements.

[Zvuchniak]

Re: A HOLM starter guide

With help of NEO Dan and Pano i fixed it. It looks like this now:



But impulse is still screwed up.

[ryanbouma]

Re: A HOLM starter guide

Big question is can i find it and fix it :(

Yeesshh! Ya, it should be a flat line along the 0db axis iirc. Something is screwed up with the settings of the sound card.

Do you have any other sound cards that could power that mic? How about another mini jack mic that you could try using the onboard soundcard.

[Zvuchniak]

Re: A HOLM starter guide

Since i disabled sound card and uninstaled drivers my mixer looks like this:

[rpb]

Re: A HOLM starter guide

I'd suggest looking closely at the settings in the Windows mixer. Mute everything except (I think), the wave files.
Look at input and output level adjustments too. There might be a mic boost as well. Sometimes it's hard to find. I think
I mentioned this in the guide. It looks like maybe you are getting a loop of some kind. Like if the HOLM signal output that goes
to the speaker amp is being fed back into the input, and then being sent back out again to the speaker amp again, and then into
the input again. Each time with a very slight delay. Or it could possibly be a sound card reverb effect of some kind. I
had a soundblaster card that I could not turn the effect off. I currently use the soundcards that came with my very basic
Compac, and Asus computers. One of my computers internal soundcard looked like a brick wall filter at about 7k.

[Zvuchniak]

Re: A HOLM starter guide

It is on the stand. Guys from DIY suggested me to do the loop measurement. To connect the output of the sound card to the input and measure it. It should be flat line but it looks like this:



There is some problem. Big question is can i find it and fix it :(

[ryanbouma]

Re: A HOLM starter guide

so that only thing that i can do settings for is M-audio.

Well in that case, I don't understand why your IR looks so bad. What I see in your IR resembles a poor microphone and soundcard with processing, ime. You're equipment is good.

Is your microphone on a stand? I've seen it before when a microphone has a very nearby reflection. Example. The mic is placed ground plane but isn't directely on the ground. That's about the only other time I've seen an IR look that way.

Sorry

EDIT - can you show a smoothed (no gating) response? And what driver is this? Is the FR known? I still feel this isn't a measurement from you mic.

[Zvuchniak]

Re: A HOLM starter guide

Hey, I'm tuxedocivic from AVSforum. I think I might be who sent you over here.

I've had this exact problem before with a laptop. I've never really put my finger on it, but I believe it's the mic in the computer just won't go away and takes the measurement. These mics often have a 5khz low pass, and that looks to be the case here also. They also have a messy impulse response and give that exact output. Same with my webcam on my desktop. Try finding that thing and turn it off. I've become very frustrated with them at times. They just won't go away, even when I disable them it seems.

By the way, you don't select your gate time based on the distance from the mic to the speaker but the delta of distance from first reflection vs direct sound. This should be visible on the IR and there's no need to do the math. The math can be a nice sanity check, but that IR is not right.

Good luck.

Hi Ryan (Tuxedocivic ) Yes, you sent me here

I am measuring with desktop computer. It doesn't have built in mic. The only thing i thought that has to do with this is onboard sound card that i disabled in BIOS and uninstaled drivers so that only thing that i can do settings for is M-audio.

You are right about selecting time gate based on delta of distance from first reflection but only if you can see the reflection. I did it this way because i can't see the first reflection. By setting the time gate at exactly the distance from mic and if i remove reflecting surfaces at at least that same distance i eliminate every posible reflection even if i don't see it.

You were talking about this

[pnoneal...]

Re: A HOLM starter guide

I turned it up and reached -20dB without clipping from mic. Here it is:

[ATTACH=CONFIG]27184[/ATTACH]

Frequency looks better but impulse is still bad. I bought connectors and making cable now. I will report later

It's a tricky process setting up the sound card inputs to proper levels. I use RMAA53 and QuickMixIn to help in this process. Here is a page where you can DL those programs to help set things up properly.

http://www.claudionegro.com/

just go to the downloads page