List of Reference Level, High Sensitivity & SPL Speakers - Page 7

CV will have to work long and hard to erase the memories of the last 20 years of poor quality.

As promised, I updated the explanation at the beginning with more info about the columns. I have not gotten to the scoring or other columns to the right yet.

I still didn't know how compression affects peaks, because most of the stuff I've read about compression was with regard to continuous or program signals.
I started a thread about this topic here.

Essentially, what I've learned so far is that thermal compression doesn't occur when you stay within the speaker's peak power handling. There may be other forms of compression such as magnetic and physical at play, and I'm still trying to find this out.

Measuring Peak Output and Distortion
This is more difficult to measure. I read that special sound meters are required to read these very fast peaks. I don't know if a typical < $200 meter or a measurement mic, hooked up to Real EQ Wizard, counts as being able to measure those transient peaks? What tone should we use? I couldn't get REW to put out a 500ms or 1 second burst tone. Linkwitz sells a CD of shaped burst tones. THX uses burst tones in its tests. CEA 2010 subwoofer tests uses such, I think?

It's hard to find info on this, either because it's hard to measure, it's not important (if you stay under max peak watts you're okay?), or a combination of both.

Thermal Compression
With enough continual (or frequent peak) high power signal being fed to the speaker, the voice coil heats up (speakers take electricity and convert a small fraction to acoustic energy; the rest is dissipated as heat).

As the VC heats up, its resistance changes. The frequency response of the speaker is now out of balance, because eg. the woofer will be producing less sound with the same watts but more resistance. You won't be getting the same bass peak level dynamics, and the speaker will sound more "bright." This is distortion, because what comes out is not what went in.

In that first post I linked to a Google spreadsheet showing four speakers and their manufacturer-stated compression specs. With bass pink noise, after only 5 minutes, the speakers compress a fraction of a dB at only 1/10 continuous power rating. At half that rating, they compress 1-2dB. At full power rating, they compresses 3-4dB.

Peaks, though, are by definition not continual. The VC has a chance to cool down.

Magnetic Compression
More typically in bass drivers, at high levels, stuff happens to the magnetic flux fields that make the power response nonlinear.

Also, the woofer can be driven so hard that it's out of the linear portion of the magnetic gap, and the field weakens.

I still don't know if that typically happens if you stay within the speaker's max peak power rating.

Physical Causes of Compression
With enough power, the driver can bottom out.

Also, with enough excursion, the spider itself is exerting a resistant force that's no longer linear, so the output from an increase in power is not what's expected: distortion.

How can you tell?
Again, there's distortion that sounds horrible and harsh, that we can easily discern, and we turn it down. This is more on continuous bass/drum sounds, and not necessarily the more infrequent peaks.

But if the peaks are just not hitting quite as loud...it's difficult to tell, except if one is cringing and wincing, it may be due to distortion on those peaks. If it's just softer, we may be missing that last icing of realism, and we would have to A/B test two speakers rapidly and tell the difference, but in judging our own speakers we may not realize it.

Also, just turning it down isn't always an option, because if the softest sounds are now beneath the noise floor of the room, then you've still lost dynamic range. Instead of losing it at the top, now you've lost it at the bottom.

MKTheater suggested the technique of playing passages of a soundtrack and using REW to measure the peaks, and I tried this yesterday with some good effect. I was testing the subwoofers, but one could do the same on main speakers, using A-weighting. It might help to know what the recorded level of a certain passage is, at what frequency, and in what channel, so that you could narrow it down better. But I don't know for sure at what point REW can pick up what short peaks at what frequency. It might be time/frequency/sample-rate dependent?

Changes to List
For now, I've removed the columns in the spreadsheet that showed what dB output you'd get on peaks, but using only 1/8th the stated power (I had thought that the rule-of-thumb of where compression starts affected peaks as well as continuous signals).

As long as typically one can avoid magnetic and physical compression by staying within the stated peak power handling, that's good news, as one can just use the simple calculator to roughly judge what output one will get.

This does deserve more investigation, however.

Done. Signature S8 at the bottom of the list, producing 105dB 12 feet away using its max peak power handling using 500w peak output amplifier.

The Seaton Catalyst will give you 115dB peaks, and includes the amps to do so.

Note: I had a Catalyst in there previously, but I've replaced it. I was thinking the 1000 watts for the LF driver was program watts. But after reading Mark Seaton's post elsewhere about reaching 126dB with one speaker a meter away, I'm thinking the 1000 refers to peak watt ouput for the LF amp. Someone correct me if I'm wrong. But if the peak is 2000w, that'd suggest that the speaker was 93dB sensitive, which seems off. Then again, active speakers give you ~3dB more sensitivity due to lack of passive crossover, so I dunno).

Removed < 105dB
With a heavy heart, I've hidden those speakers that cannot produce 105dB with their peak watt rating. It gets to be too confusing, I suspect, to have a list with a stated purpose, and then also see a smattering of other speakers that either almost made it, or are there to illustrate how much they don't make the grade.

I've put the bottom-feeders on another "naughty" list.

Seriously, many of those speakers are fantastic, for their own reasons. Beautiful cabinetry. Incredibly detailed. Great on and off-axis response. Smooth, buttery, etc. But I gotta draw the line some where.

Note that other speakers like the KRK Expose, and Procella P6 also fell off. As I learn more about how to interpret their active amps this might change, as they're only 1.4dB short!

I'm open to suggestions about this.

Corrected and Added Axioms
I read about the Axiom VP-160 today, and I was gratified to see, instead of three horizontal woofers, or two tweeters, instead I saw a design with two woofers, and a mid below the tweeter, which I understand mitigates lobing problems in the critical midrange. I thought, "I'd better add this, and other Axiom speakers to the List!"

I was aghast to find that the one Axiom speaker I'd added a while back had the sensitivity too low. Axiom is great in that they specify sensitivity as full space (anechoic). Their in-room sensitivity is always 4dB above anechoic, instead of the 3dB that others report. I'm curious as to the difference in calculations or measurements.

Anyway, to help atone for my mistake, I endeavored to add all the Axioms I could find that would be worthy of the List.

You'll find the M22 (corrected to 93dB), the M3, which is a larger bookshelf (92dB), the M50 floorstander (94dB and only $828 a pair), and the VP160 (93dB $570).

I do wish their frequency response was given with -3dB points, though.
And I don't know whether their "max amp power" means program power, and thus a recommended amp spec, or peak power? I assumed the former, but someone correct me if I'm wrong!

Added SVS
I had not paid much attention to SVS previously. I like the company, I own one of their subs. But I was disappointed to find that a company known for class-leading subs that are high-output, decided to make the majority of their speakers more intended for critical listening at closer distances, at lower volumes.

I know they, and fans, would vehemently disagree, but that doesn't change the fact that their sensitivities often range from 82 to 85dB. I'm sure that the design yields incredible detail and imaging, but I'm still really surprised. Reference level would require 1,500 to 2,670 watts, 500% to 1,100% over what they're rated to handle (and that's my giving their max power rating the benefit of the doubt that it was Program and not Peak!).

After adding the speakers, I later decided to hide those that can't do 105dB, so all but on SVSound speaker disappeared: MBS-02 (82.5dB), SBS-02 (82dB), and the SCS-02 (84.5dB). These speakers will do -10dB on a calibrated volume, if you feed them 300-400 peak watts. I don't know if an XPA-3 is a design with 3dB headroom as some are, but if so, then that amp would fine.

Their high-end tower, the MTS-02 ($1,399) makes the grade, even with only 88.5dB sensitivity, by virtue of the 600w power handling. If I'm wrong about their power numbers, then it'll fall off the list.

 

Reference-Capable-Speakers.pdf 442.220703125k . file

Several of the speakers are no longer made.

And several are cheaper stage speakers, and I don't know how they sound. So those Athena are perfectly appropriate.

Good finds, I will add them! Can you find out if their sensitivity is anechoic ?

Good stuff. Strange that the S3 is so far off!

They have good extension, at the sacrifice of sensitivity.
The power handling suggests it would reach reference level if you throw the 300 to 600 watts at it. 100 watts will get you reference level minus 5dB.

This one was already on the list (barely, at 104.8dB!).

Opposite of Axiom, they're saying the anechoic (90dB) is 2dB below the in-room (92dB).

I added the Aperion 6T, although it looks like it's discontinued. What's the used price go for now?

I also added its replacement, the Versus Grand. Looks like the Grand traded a little extension for another 1 dB of sensitivity, which for this list, is a good thing.

Until I hear otherwise, I'll assume the anechoic sensitivity is 3dB below what they post, since they didnt' qualify it.

Ha, I was actually on the verge of seeking you or one of the other active speaker afficiandos for help! If you read through the thread, or more easily the initial explanation I give at the top, I am practically begging for help on this topic.

I did come across the "no analog crossover = 3dB more output" issue you reference, and I've wondered about that. However, I then have to consider that if I use the manufacturers' own peak SPL numbers, combined with their peak amp output, as the basis for coming up with an extrapolated sensitivity, have I not then accounted for their efficiencies in active amplification with no passive crossover?

For instance, the Genelec 1038CF is given as 118dB SPL for a "Maximum short time sine wave acoustic output at 1 m on axis in half space, averaged from 100 Hz to 3 kHz." Their bass amp is also 180W (short term output power). They give some excuse about power protection when they don't give a continuous rating.

If I plug 180w @ 3.3 ft, near a wall, I need 93dB to reach 118dB.

If this speaker will do 118dB at 3.3 feet, do you think it will produce 107.3dB at 12 feet?

Two questions remain for me, though:

• was that 180w the peak that the amp can provide? If it is, then I should use 180w as the peak watts, instead of 360w, and its max output will be lower than what's stated for 12 feet anechoic.
• Should the 180w be spread over the two bass woofers of the 1038CF? And with less available power for each woofer, then my pseudo-sensitivity should be higher. EDIT: No, I don't think so, because we're measuring an entire speaker at that frequency, not one driver.

Another active speaker is the QSC K8.
It's rated as 500w continuous / 1000w peak to the bass driver, and 127 dB peak SPL. They note that their max SPL is calculated from the driver sensitivity and peak available amp power.

Using 1000w, 3.3 feet, and 94dB sensitivity, in-room, I get 127dB SPL. At 12 feet, anechoic, the spreadsheet shows 112.7dB.

Although it's possible QSC calculated for anechoic, but I doubt it, because if they did they probably would've stated such.

Separate Chart?
You're right, a separate chart might make it more clear. I can see how people would look more closely at the sensitivity, which matters less if the on-board amps are capable enough.

However the SPL output numbers seem in line with what the manufacturers are touting.

Maybe the biggest need for a separate chart is to make it clear to people that the active speakers include amplification already, so if someone hasn't bought their amps yet, this is a cost savings and adds to the apples-to-apples comparison.

Note to compare the active speakers on equal ground, one still has to play with their SPL numbers to put them all on anechoic, 1m. I saw some companies quoting 2m distance, or with multiple speakers in play.

I appreciate your help in making these numbers more representative of what the speakers can do!

I'd love to include them! What is their sensitivities and power-handling? I don't see these on their respective websites.

I'd also love to include some Econowaves, but I haven't seen their numbers either.

I added this Cerwin Vega INT-252 speaker.