HOLMImpulse: Measurements in practice

[speakerdoctor]

Here's my first two measurements worth uploading

Blue is a 3 way AS classic speaker.

Red is a 2 way AS classic speaker - different brand. Red one'w woofer runs full range w/no series coil. Wonder why all the phase inversions.

Blue one was measured on the floor. Red on was measured a couple of feet off the floor.

[Key]

Never seen a measurement of that card but even if I did there are other mitigating factors - power supply, EMI, Bios settings for PCI etc....

In HOLM under Device & Signal to the right under calibration is where you would calibrate your ADC/DAC loopback.

[speakerdoctor]

Originally Posted by Key

Never seen a measurement of that card but even if I did there are other mitigating factors - power supply, EMI, Bios settings for PCI etc....

In HOLM under Device & Signal to the right under calibration is where you would calibrate your ADC/DAC loopback.

Thans Key. Soundcard calibration routine reported it's accurate within +- 3 dB from 8 to 21 kHz. I'd say not bad.
Although keep getting msg. saying there's clipping. Don't know how to 'turn it down'?

[Key]

Originally Posted by speakerdoctor

Thans Key. Soundcard calibration routine reported it's accurate within +- 3 dB from 8 to 21 kHz. I'd say not bad.
Although keep getting msg. saying there's clipping. Don't know how to 'turn it down'?

Same tab Device and Signal under output device is PCM amplitude. Might want to lower it. If that doesn't work lower the Art MP. Basically if you are clipping the inputs you have to turn down whats feeding it or else all you are doing is turning down a clipped signal.

Sorry if you already understand this but I just see this question pop up frequently with people recording from vinyl expecting to be able to turn it down within the computer not realizing they are clipping the analog stage of the soundcards inputs.

[Pano]

Gain structure is very important, yes.

[Key]

Some (including me) might argue it is the most important thing. Outside of having gear that actually works/interfaces properly.

[speakerdoctor]

Originally Posted by speakerdoctor

Here's my first two measurements worth uploading

Blue is a 3 way AS classic speaker.

Red is a 2 way AS classic speaker - different brand. Red one'w woofer runs full range w/no series coil. Wonder why all the phase inversions.

Blue one was measured on the floor. Red on was measured a couple of feet off the floor.

Mr. Holm. What does the dash line in the impulse response represent? It curves down from the top of the graph and slopes down to the right.
And, why can I take one dashed line and move it to match the shape of another dashed line if I have taken two measurements?

[Pano]

Do you mean the time window in the impulse measure?

[speakerdoctor]

Originally Posted by panomaniac

Do you mean the time window in the impulse measure?

There's more than one window in the impulse measure?

I was referring to the default impulse measure window.

[domtw]

Originally Posted by Ferrit37

Hey Guys,
The problem with impules response alignment is that the peak of the impulse is where the highest frequencies are, so if you align the peaks, of say the HF and LF, your joining the "wrong ends of the stick" as it were.
Examining the relative slopes of the phase trace through the crossover region and getting them to agree seems to be the best way to get these components into alignment.
By adjusting the arrival time so you get the phase slope to be horizontal for one band you know that you are looking at when that energy is arriving. Without changing the delay time you now can see if the the other band is arriving early or late by looking at the phase slope.
It's this area of interaction between bands that needs attention.
Two signals of equal amplitude will have the most interaction.

I am now back into practice and need a few more details about the above method for time alignment.

If I look at the phase of each driver separately, I can find an area (for the twitter position, relatively to the woofer) where those two phase plot seem to agree.
My problem is that by looking at this agreement, I cannot find a very precise position for the twitter.
I would think that in a range of 1-2 cm, the 2 curves are kind of agreeing.

Originally Posted by Ferrit37

By adjusting the arrival time so you get the phase slope to be horizontal for one band you know that you are looking at when that energy is arriving. Without changing the delay time you now can see if the the other band is arriving early or late by looking at the phase slope.
It's this area of interaction between bands that needs attention.
Two signals of equal amplitude will have the most interaction.

I am not sure how to do this in HOLM Impulse.
Could you, please, develop that part?

Thanks