• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Speaker distortion

Sal1950

Major Contributor
The Chicago Crusher
Forum Donor
Joined
Mar 1, 2016
Messages
8,709
Likes
8,077
Location
Central Fl
#1
Subjectively, this is my experience too. I hate to mention such a subjective belief/theory on ASR, but I am a believer in this.
Not really purely subjective. The improvements gained from large woofers over small are easily measured.
 

JohnBooty

Senior Member
Forum Donor
Joined
Jul 24, 2018
Messages
490
Likes
1,040
Location
Philadelphia area
#2
Not really purely subjective. The improvements gained from large woofers over small are easily measured.
I'd like to know more about this. How are they measured?

I know that cone breakup (a potential downside of larger cones if not crossed over properly, right?) is pretty easily seen in FR graphs.
 

JohnYang1997

Major Contributor
Technical Expert
Manufacturer
Joined
Dec 28, 2018
Messages
5,945
Likes
11,764
Location
China
#3
I'd like to know more about this. How are they measured?

I know that cone breakup (a potential downside of larger cones if not crossed over properly, right?) is pretty easily seen in FR graphs.
Max spl. Flatness of bass. Harmonic distortion of bass.
 

JohnBooty

Senior Member
Forum Donor
Joined
Jul 24, 2018
Messages
490
Likes
1,040
Location
Philadelphia area
#4
Max spl. Flatness of bass. Harmonic distortion of bass.
Hmmm...

Max spl: Yes, for sure. But, the benefits seem apparent even nowhere near high SPLs? I've never done blind speaker comparisons, though. So my impressions are surely biased.

Flatness of bass: This is trivial to achieve via DSP on any speaker, though, right? (And is going to be highly room-dependent anyway, without DSP)

Harmonic distortion of bass: This makes 100% sense to me. Though, you so seldom see measurements for speaker THD. I think amplifier load plays a big issue here. Larger woofers tend to be more efficient, and therefore can present an easier load to the amp?
 

JohnYang1997

Major Contributor
Technical Expert
Manufacturer
Joined
Dec 28, 2018
Messages
5,945
Likes
11,764
Location
China
#5
Hmmm...

Max spl: Yes, for sure. But, the benefits seem apparent even nowhere near high SPLs? I've never done blind speaker comparisons, though. So my impressions are surely biased.

Flatness of bass: This is trivial to achieve via DSP on any speaker, though, right? (And is going to be highly room-dependent anyway, without DSP)

Harmonic distortion of bass: This makes 100% sense to me. Though, you so seldom see measurements for speaker THD. I think amplifier load plays a big issue here. Larger woofers tend to be more efficient, and therefore can present an easier load to the amp?
It's the distortion of the driver itself. The physical ability to extend to lower frequency which is hard to achieve with smaller size.
The frequency response also goes hand in hand with distortion if you consider eq. And if you think of it all three are related. Normally one has to attenuate tweeter and mid range a lot to get flatter frequency response of bass from smaller speakers. And that requires a lot of extra power. And max spl is fixed hence bass is only so much. When driver reaches spl, excursion limitations the distortion goes shit. If you eq your speakers too hard the distortion will go shit and you will lose a lot of digital headroom, 20dB+ we are talking here.
Just read some speaker measurements, it's very straightforward. You can compare a few speakers from, for example, eve like eve sc203 204 205 207 and 30x. There are graphs. https://eve-audio.de/index.php?page=SC204
 

HammerSandwich

Addicted to Fun and Learning
Forum Donor
Joined
Nov 22, 2018
Messages
831
Likes
969
#6
A few additional thoughts about this...

Hofmann understood that attempting to make a small woofer perform like a large one creates feedback effects that work against you. You could use 4x 6" woofers to equal 1x 12", but then you have the same cone area & a similar box volume. Matching performance with a single 6", power & excursion just ain't the same.

Why? It's all about the side effects of inefficiency.

As John pointed out, you can EQ woofers to a given FR, but this requires more power. Compared to a 12" woofer, a less-efficient 6" requires not just 4x greater excursion but also significantly more wattage to produce it. Simultaneously, that power drives a smaller motor, so temperatures grow much higher. As the coil's wire heats up, its resistance changes. Non-linearity!

Thiele-Small parameters come from "small signal" tests, meaning at low excursion. But a driver's characteristics vary with excursion (and not the same in both directions!), meaning those parameters are not static. IOW, a 6" woofer cannot be as consistent as a 12" at a given SPL, but especially as SPL changes. Klippel testing is worth a look here - it shows how non-linear suspensions & magnets are in these dynamic situations. Check out a few driver tests at Audioxpress.

TLDR: inefficiency always has costs, and a woofer's size is related to its efficiency.
 

Mnyb

Addicted to Fun and Learning
Forum Donor
Joined
Aug 14, 2019
Messages
956
Likes
1,204
Location
Sweden, Västerås
#7
Is not woofer distortion so bad that it’s sometimes called doubling . A woofer overextended actually plays much more second harmonic than fundamental tone effectively doubling the frequency of some bass tones,
I think ( unproven ) that this is why some thinks that speaker systems with very clean bass sounds thin , couple that with bad impulse response and you have that fat bass sound ? Add a bit circle of confusion to that , modern music mixed on such speakers ?
 
OP
Sal1950

Sal1950

Major Contributor
The Chicago Crusher
Forum Donor
Joined
Mar 1, 2016
Messages
8,709
Likes
8,077
Location
Central Fl
Thread Starter #8

direstraitsfan98

Addicted to Fun and Learning
Forum Donor
Joined
Oct 1, 2018
Messages
828
Likes
1,149
#9
If I wanted to do distortion measurements for my drivers what equipment would I need and how would I go about doing so? There does seem to be some fairly comprehensive measurements available for my speakers here but I'd like to verify them myself with my own hands. Scroll down to the bottom portion of the review and you can see them.

I wholeheartedly agree with HammerSandwhich above me. What I came to realize having jumped from KEF LS50, to Harbeth 30.2, and Arteluthe Cadenza, was that bigger drivers equates to bigger sound. The swiftness and accuracy of percussion can't be replicated to the extent it can be on a large woofer. I do believe it has something to do with distortion... and I as well cannot explain why.
 

wynpalmer

Active Member
Joined
Dec 14, 2018
Messages
114
Likes
103
#10
If I wanted to do distortion measurements for my drivers what equipment would I need and how would I go about doing so? There does seem to be some fairly comprehensive measurements available for my speakers here but I'd like to verify them myself with my own hands. Scroll down to the bottom portion of the review and you can see them.

I wholeheartedly agree with HammerSandwhich above me. What I came to realize having jumped from KEF LS50, to Harbeth 30.2, and Arteluthe Cadenza, was that bigger drivers equates to bigger sound. The swiftness and accuracy of percussion can't be replicated to the extent it can be on a large woofer. I do believe it has something to do with distortion... and I as well cannot explain why.
I use a calibrated mic and REW for speaker distortion measurements. REW recommends UMIK-1, but I use the XTZ Room Analyzer PRO II mic.
Both mics have supported calibration files. Using the setup I can do a full frequency range sweep of distortion and determine the variation of distortion versus speaker loudness.
I don't have full results at my finger tips, but the bass drivers produce distortion in the -46 to -30dBc (20Hz-c. 300Hz) range depending on amplitude while the electrostatic panels never exceed -50dBc (c. 300Hz- 20kHz) under amplitude conditions that correspond to what would be a very loud listening condition.
The bass units consist of a pair of 10" drivers/channel for c. 40Hz and above, and a 15" sub for 40Hz and below.
 

Juhazi

Major Contributor
Joined
Sep 15, 2018
Messages
1,511
Likes
2,322
Location
Finland
#11
Smaller cone area has lower acoustic efficiency (coupling to air), it's one reason for higher distortion in addition to T/S limits. The small cone sort of slips and slides in the air instead of pumping it effectively. Sound volume/dB means air pressure variation, and a driver's air volume displacement capacity is crucial. Compensating membrane area with high excursion leads to many problems. Horn loading is a smart way to improve efficiency/coupling, but for bass the size of the horn needed is huge.

Loading down to 30Hz
 
Last edited:

Soniclife

Major Contributor
Forum Donor
Joined
Apr 13, 2017
Messages
3,779
Likes
4,211
Location
UK
#12
Smaller cone area has lower acoustic efficiency (coupling to air), it's one reason for higher distortion in addition to T/S limits. The small cone sort of slips and slides in the air instead of pumping it effectively. Sound volume/dB means air pressure variation, and a driver's air volume displacement capacity is crucial. Compensating membrane area with high excursion leads to many problems. Horn loading is a smart way to improve efficiency/coupling, but for bass the size of the horn needed is huge.

Loading down to 30Hz
Is the bench meant to be the listening position? Going to be very little crosstalk between the channels like that.
 
Top Bottom