Dayton OmniMic Precision Measurement System - Page 8

The 1980 Siegfried Linkwitz paper "Shaped Tone-Burst Testing". He just added this paper today.

http://www.linkwitzlab.com/JAES/jaes_papers80.htm

Warpdrv I will use SL to analyze the a sine signal coming out of a piece of gear and you can see when the signal starts to have a big jump in distortion. You can run a few different frequencies through just to make sure the performance isn't drastically different. Go through each piece of gear one at a time and you can ensure that you aren't going to be overdriving anything but still getting a clean strong signal.

J I'm not using too fast of a scroll speed I just meant that I adjust it depending on what I am looking at. I don't usually try to analyze 3 min of signal at once like some people do when looking at movie soundtracks.

Seems like there are about 4 conversations here that have been had before.

I agree, but, IMO, these are conversations that haven't been had anywhere else on Earth before, so they bear repeating a few times.

I don't think I'm alone in sensing that there is a next step evolution about to occur (or, at the very least due to occur) regarding how low frequency recorded program source and the subwoofers used to reproduce it in a home environment are evaluated.

We've been through the phases of alignment worship and driver motor technology as well as the requirement and usefulness of various outboard hardware and amplifiers.

There are goods and bads in all of them. It's time there was a routine way to examine those goods and bads in-room to truly benefit the average enthusiast.

IOW, when you refer to subwoofer testing and test results, there is only a tiny minority whose eyes don't immediately glass over and half of them are misinterpreting those results.

People get a sub (or build a sub) and post their experience like this: "I threw in WOTW at reference level and this bad boy handled it without breaking a sweat!" They usually don't say: "I threw in Siegfried's shaped tone burst CD and..."

Instead of DIY vs commercial, ported vs sealed, TH vs FLH vs TL vs BP, etc., etc., it should be the room vs various alignments with various program source with a simple guide to the strengths and compromises of each approach so that the interested parties can decide where they want to start and where they want to aspire to be.

FWIW, that's what I've been getting out of this sort of thread, many times without realizing it, so, please... repeat away.

Bosso

Oh I agree that the conversations are interesting but they pop up out of the blue sometimes. I totally agree it is time for something better than a fr taken with an rs meter and a generic cal file. I hope this product is a step in that direction. I also agree that the types of comparisons you've been doing in SL are a much better judge of playback accuracy than a 80 db fr sweep. I've still got changes going on to my main system but I plan to try a few myself at some point. Super busy lately. Call me old fashioned but I am still very interested in performance of the drivers and enclosures themselves in a vacuum just for ease of comparisons sake you know? The ability to discern the properties of your application and environment that you intend to implement a system into, whether a ht room, outdoors, in vehicle, commercial theater, or large venue is also a very powerful tool. I look at it like a two part equation. Big strides seem to be being made in easily and affordably investigating both areas. Especially the environment.

Btw the amp you are using now...is it universal voltage? Either 120 or 240 v? I'm looking for something like that soon.

bosso, that is one of the most well reasoned posts that i have seen, as it recognizes that different folks may prefer different subs. some folks prefer greater spl up high, while others may prefer greater extension. of course, having it all is best, but that has its own tradeoff...lots of money. +1.

Most if given the real choice will want the most accurate response. All other choices are simply from a lack of education and more importantly an experienced reference point.

LTD02 no matter how many posts you make trying to support a specific sub, no one really wants peaky SPL performance

There are better solutions but if people refuse to accept science and refuse to understand that their point of reference is generally lacking they will never obtain the best solution.

Starting to sound a little elitist there.

The fact is, most people dislike an "accurate" sound. That doesn't make them wrong, uneducated, or ignorant.

What is "accurate" from overly processed/synthetic music anyway? I have never seen a professional studio with anything like something I would consider an "accurate" playback setup. In fact most of the people I know in the "biz" use ghettoblasters and car systems as the finale quality check in the mastering process to make sure their products sounds right on the types of systems the music will be played on. This is also why a lot of popular music sounds "light" on an "accurate" system.

Edit: It's probably best to ignore me today as the in-laws were here all day.

"LTD02 no matter how many posts you make trying to support a specific sub, no one really wants peaky SPL performance"

where is this comment coming from penn?

i've suggested countless different subs in countless different designs for countless different applications over time and you know that.

Yeah but not all of us listen to such music.

You really want to have fun ask him about wave guides. Use the word speaker kin a post and he will push it BUT he will tell you his ribbon speakers sound better then the wave guide speakers (must be more accurate) and then tell you the waveguide is better.

i get the sense that penn is honest with respect his comparisons and i am familiar with what you are saying. penn and i have pretty much common thoughts on waveguides. i'm not going to make a single post a big deal. we all get a little carried away sometimes, for one reason or another. i just don't like being called a "fanboy" of any particular design when i have a long history of supporting all kinds of different designs for all kinds of different applications.

That is fine too, but it is not a reason to talk down to those that do, and he did say "most," and "no one really wants peaky SPL performance." If you replace either with "I" then it's all good, but as it stands it is not true at all for the majority.

What do you consider "such music?" Unless it is a live recording from one of the specialty labels it has been processed and EQed to "sound" "correct" on whatever the house was monitoring with.


It's probably best to ignore me today as the in-laws were here all day.

"It's probably best to ignore me today as the in-laws were here all day."

:-) sometimes that can make one want to blow a gasket. i definitely know where you are coming from. it's been this way for hundreds of years though. take a breather, have a cocktail or two, exhale...., all is good. :-)

Anything other than well-recorded acoustical classical music.

The type of music involved changes nothing in the debate. Regardless of how processed or unprocessed, the presentation is always best with a calibration that most accurately renders the ones and zeroes as a baseline.

Personal preferences that deviate from that baseline are irrelevant if the system has the flexibility to offer an accurate rendering as well as tweaks to suit those preferences.

If the system is, as Penn mentions, "peaky" or "tilted" or bandwidth-limited to conform to a limited budget or distorted personal preference, then there is little hope of calibrating to an accurate baseline, which is not a good thing, ideally and renders any discussion of accurate measurements useless.

Going back to my earlier post, I don't know how many times I've read a post that says "My sub handled the WOTW lightning strikes with no problem", from a guy who has a 20 Hz tuned ported sub.

Huh? You could just shut the sub off altogether and make the same statement.

I never have understood how anyone could argue otherwise.

Bosso

bosso, i'm 95% with you.

let's explore the 5% though.

take a commercial theater. would not 8 or so pro audio subs tuned to around 25 hz not 'please the masses' more than an equal number of sealed subs?

into a *very* big home theater...4 or so pro audio subs tuned to around 25hz will be a winner.

as you get down to medium or small sized room, i agree, multiple sealed win as they allow for subharmonics down below 10hz.

for some fun bass that does not conform to the bossobass strategy:

http://www.basspig.com/

lots of options = win.

I just found the point very interesting considering the current discussion on CHT subs.

Anyways, this discussion is 100% of topic.

Is the Dayton Measurement kit in stock and/or anyone have one yet?

You are posting some inaccurate summaries with very bad generalizations.

I would post that for dynamics in movies, waveuide/pro audio designs are better (Yes better then statements or Clearwave speakers). Put 10 people in a room and do a properly controlled tests and 9 out of 10 will come out of that test listing clean dynamics, controlled directivity as top priority. Until you do it, you can enjoy drivers that can not do clean dynamics and designs that dont have control directivity YOu want a high end HT room??? You need to have clean dynamics and controlled directivity. Those are top priorities for the best HT experience.

I choose ribbon designs for 5 foot listening distance and I choose waveguide/pro drivers for high end HT.


Again, another off topic. I doubt LTD02 will have any issue here, he has agreed many times on that topic. My post was just an inside joke to him and nothing more.

Commercial theaters easily have the means to present the complete soundtrack. After all, it is the 21st century and the Dolby spec is 20 years old. They don't because modern cinema is a multiplex venue located in a mall or strip mall where the <25 Hz content bleeds into other locations and theaters, causing complaints.

Bass Pig is the perfect example. I visited his site a long while back. I would have thought we'd come a long way since then.

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.

I never had to employ any technical wizardry to get flat to 4Hz other than have a signal chain that doesn't roll off before then.

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.

Brian Ding (a real engineer, and one who has taught me volumes about low frequency audio) has offered a 1x12" sealed system with selectable 14 Hz F3 for many years.

Bosso

Bosso I agree with you on most things but the steadfast implication that sealed or IB is always the correct answer for every application I disagree with. I mean I'm with you most of the way as I would always use sealed or IB in a car audio install or with enough cash to do it right in home audio or HT. I don't plan to use any other alignment for my personal systems in the future but there are situations when a different approach can be a better fit. Every system has a compromise to it. Sealed being cost, weight and power requirements especially to fill a large space for someone with limited budget, who likes things loud and with headroom. Worrying about the bass below about the mid teens in that scenario is just not worth it.

Hey did you see my amp question?

If you have to a fill a large space with a budget, sealed is not even an option which is why you really don't see that design used in pro audio expect maybe in recording studios where the budget is relatively high for the volume of space they need to fill.

and even in the recording studio it seems rare.

5 seconds of 50hz.

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

Kyle i would like to hear your opinion about Passive Radiators in terms of their price performance.

If you could design a system from scratch and it had to be a complete system ( box, amp, driver, PR everything ) with the objective being cost effectiveness and ported alignment being off the table ( not an option ) would you go with sealed or PR ?

it is obvious that given a driver that can handle a PR and having the space - it is more cost effective to use it than use two drivers. but what if you're designing the driver and by going sealed you can design a cheaper driver ?

did you try to model the cost considerations here ? i find it hard to figure out this question without the kind of modeling that only somebody like you could be reasonably expected to have performed

design and tooling costs would probably be on the side of the sealed. but what about materials and manufacturing costs ? total cost ?

"Commercial theaters easily have the means to present the complete soundtrack. After all, it is the 21st century and the Dolby spec is 20 years old. They don't because modern cinema is a multiplex venue located in a mall or strip mall where the <25 Hz content bleeds into other locations and theaters, causing complaints."

you've said this before and i have disagreed. what data backs your claim bosso?

Still on the boat, eh? Hmm... I give it 2-3 weeks minimum but I'm not in any hurry.

Hard to believe this high cost rumor persists. Sealed covers a lot of ground, up to and including IB, which is the most bang-for-buck and simplest to design and build HT sub there is, both from a $ standpoint and real estate requirement.

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

My preference is for multiple small subs with flexibility in signal shaping and plenty of amp, so double the budget and add labor.

Headroom has been redefined over time to the point where it means something altogether unrelated. I've covered that road. With a current 12x15", 16kw system I can tell you that the only use for that much capability is bumping the levels to 10 times above reference, not headroom.

When properly calibrated and at reference playback level there is zero difference in performance between that system and 1/2 that system. So, with the larger system, it's more accurate to say higher dBSPL instead of more headroom.

No, sorry I missed the amp question. The amps need to be specified at the git. They have a wide tolerance parameter (100-120V, 50-60Hz), but not so wide that they'll do both 120V and 220V. I'm sure that I could get that feature added at some point, but I currently have no such plans.

They have 3 high quality 60cfm Sunon Maglev fans and run cool as ice, but that sort of air movement capability is loud. I'm looking into less air and quieter fans, but to this point I'm extremely happy with performance and I keep all of my amps in closed cabinets.

PM me if you're interested in further info.

Bosso

Bosso,

I'm looking into getting an amp that will operate off of 110-250v and generate 6kw or preferably more all while not having a low end robbing HPF in it at least till 5hz or so anyway. I know of a few but I'm trying to stay out of the $4-5K range. Around $2k or less would be much better.

I wouldn't call the high cost a rumor. Knock out IB from the equation as the majority of people don't want to or can't go with that option and it is going to be hard to pull off with a reasonable budget in a large room especially if very high output levels are needed.

Classic Fourier decomposition. The faster/steeper the transition of a waveform, the more broad band the signal, and particularly the more high frequency content there will be. An 80Hz low pass will modify the waveform and the spectral plot very visibly. Many mis-interpret this difference as a subwoofer being slow to respond, but the reality is that the contribution of the "fast" acoustic events are handled by the main speakers, as they don't exist below 100Hz. You might do a favor in understanding if you do a with/without plot of both the waveform and the spectrogram with a 4th order L-R low pass at 80Hz in the chain. We have some time before the OminMic starts shipping.


Having poked around at the potential of big VLF subs in the cinema market, the concern of controlling the spill/pollution of VLF energy is a real concern in all but the most luxurious cinemas.