Dayton OmniMic Precision Measurement System - Page 13

Originally Posted by noah katz

Are you measuring in the same location(s) you had the Audyssey mike?

Because it would never give you a nice downsloping response like that (-10 dB from low freq to high).

And which version of Audyssey? It doesn't seem to be doing so great at smoothing the response except in the bass.

Do you have Audyssey Pro?

It'd be interesting to see how its graphs compare to OmniMic's.

Originally Posted by soho54

In the dual graph which color is Audyssey, blue? Not much amplitude correction there.

Originally Posted by Gooddoc

What are your thoughts on the manual calibration graph?

Originally Posted by ltd02

5 seconds of 50hz.

Not sure if they are distortions or not, but the wideband effects at the start and stop are clear.

Originally Posted by Gooddoc

Close to the same position. It's Audyssey XT32 in a Denon 4311. I did the quick manual calibration so I had an idea of how things would look like without EQ and to compare. I have an Audyssey Pro kit coming, but it's been on order for weeks...
What are your thoughts on the manual calibration graph?





Yes, Audyssey is blue. Not so great, right?

Originally Posted by t6902wf

How much was the Audyssey Pro kit? Did you buy it directly from Audyssey?

Originally Posted by noah katz


I said to myself "That might sound pretty darn good". Not sure whether the rise in upper mids would be strident; could be fine with the rising bass though.

How does that response sound to you?

How do you manually calibrate?

Originally Posted by noah katz

Re the SPL, I was reading through the manual and it said not to use the RTA and/or spectrum analyzer for SPL; I didn't really understand the explanation.

Originally Posted by soho54

In the dual graph which color is Audyssey, blue? Not much amplitude correction there.

Originally Posted by bossobass


I have to disagree. After stretching the traces to a graph I'm more used to seeing, he goes from +/-8.5dB to +/-3dB from 30-100 Hz. But, look at the boost Audessey applies; +8dB from 25-30 Hz!

Doc,

If you get a chance, what room size, how far is the mic from the sub and what sub? Can you do a close mic of the sub to see the room influences?

Bosso

Originally Posted by bossobass

I have to disagree. After stretching the traces to a graph I'm more used to seeing, he goes from +/-8.5dB to +/-3dB from 30-100 Hz. But, look at the boost Audessey applies; +8dB from 25-30 Hz!

Originally Posted by soho54

Disagree? You need to stretch that graph on out. It wasn't an LFE measurement. Noah caught it.

His low end is ~13dB higher than his treble. What is really scary, is that exojam's looks the same.

Never been a big Audyssey fan myself.

Originally Posted by soho54

His low end is ~13dB higher than his treble

Originally Posted by noah katz

I wish Audyssey would do that to my bass; I have to boost it 10 dB.

Originally Posted by bosso

BTW, it doesn't take the kind of overkill many here engage in to get full BW replay at normal (-10dBRL with the sub running a bit hot) levels and the subsonic reproduction is simply a consequence of using the 2nd order roll off sealed alignment

Just build a sealed L/T'd system and stick the box in a corner and there you go. If you prefer higher SPL, add more. Pretty simple if you ask me. Never saw what the fuss was about.

4-18" IB drivers and a budget amp will cover reference level LFE for any room I've been in for $1500.

Originally Posted by SteveCallas

Aside from the fact that this all doesn't really work, it's a great story

Ilkka's measurements (which are still posted on the internet at a different forum) of a sealed Adire Tumult 15" show 100% or greater THD at 10hz at 2m GP at 90db. Corner load the sub to gain more output sensitivity, but the distortion comes with it. You're looking at about 60db 2m GP before the distortion becomes reasonable at 10hz. How little amplitude before it becomes reasonable at 5hz, 20db? Sure, don't forget your room gain of about 6-8db per octave starting around 25hz, but the distortion comes with it. You're going to need a ton of drivers to accomplish what you speak of without >100% THD my friend, a ton.

He then went on to measure the LMS-5400 18", what many would consider the most capable low distortion subwoofer driver available. 93db at 2m GP at 10hz with about 25% THD. 83-84db to get to a level where the THD is reasonable. How much amplitude to make that reasonable at 5hz, maybe 30db? Thats a lot of drivers to get to 118db, as spl grows by 6db when you double displacement, so driver count gets out of hand really quick. Don't forget the amps!

Now don't get me wrong, going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD. If we get this rotary subwoofer going as a diy project, then 0.1-120hz capability at reference with far less than 100% THD may be available for the masses.....or at least the <1% of the masses who are interested.

Didn't mean to interrupt discussion about the new Dayton mic, but I couldn't let that go unchallenged.

This post is at the top of the list of reasons why I'll be moving on.

Originally Posted by penngray

But, but.....we have missed the Callas vs Bosso debates

going for full subwoofer bandwidth is something I am in favor of. Using drivers - especially sealed - is just too inefficient though, especially if you want less than 100% THD

Originally Posted by FOH

Steve, I've read quite a lot of your posts, however this statement here;



really needs some added context, or outright explanation in more terms other than citing one isolated example. This painting with such a broad brush seems as gross oversimplification at best. Obviously, I'm missing something.

For my DIY attempt at addressing the LF in my room, I looked at all the alignments and went sealed (IB) due to many factors, however higher THD wasn't one of them.

Thank you

Originally Posted by bossobass

Sorry, I never look at the top side. IMO, treatments and placement are everything. I don't believe auto EQ can do much up there (or anywhere for that matter)

It did the same to mine. It boosted the sub to stupid. It seems that Audessey leaves the peaks and boosts everything around them to flatten. The opposite of what most have said is preferred.

Bosso

Originally Posted by maxmercy


Close.....Audyssey provides an inadvertent boost to material below 20Hz, it is a known fault.

These are line outputs from the subwoofer out of a Denon Receiver with MultEQ XT.....

First up, Audyssey off:

Next, Audyssey on:

Note that Audyssey has raised the entire level of the signal and applied cuts.

Now, both traces together:

To see that Audyssey just applies cuts then raises the entire signal level, move the Audyssey 'on' trace down:

This is the inadvertent 'boost' Audyssey provides. I had a message dialogue with Chris Kyriakis about it, and my solution was to implement a high-pass filter. Not many sub systems can take an 8-10dB boost below 20Hz....

The other reason Audyssey can make the low end too robust is if Dynamic EQ is engaged, as it boosts both low and high end to account for ELC as you turn MVL down from reference.

Another factor is the target curve used. Audyssey has several target curves, flat and the 'audyssey curve', which rolls off the highs somewhat, just like they are in a theatre due to the screen losses and distance propagated, as the air preferentially attenuates high freqs....to better simulate the 'theater experience', and just in case you are getting the master on the disc from the mixing stage, and not a near-field mix that would compensate for the in-theatre hi freq losses.....

JSS