Hi everyone,

I would be interested for your thoughts on this issue, as I've noticed that the quoted bass extension of some Beovox and Beolab speakers appears to be debatable and others seem to change depending on which year's brochure you read.  I know that the measurement criteria have changed over the years, but I thought it might be interesting to do a little survey of "real world" bass extension using various active and passive B&O speakers.  I have uploaded an MP3 file to the web page below (see "How can I test the bass response of my loudspeakers?") which gives a descending bass note from 350Hz to 20Hz, with an announcement before each tone so that you know what note you are listening to.  Here is the link to the page:-

http://soundsheavenly.co.uk/faq.htm

Please feel free to download the file (it is not subject to a licence or copyright) and test it on your B&O system, then post your findings.  There is also a 20Hz test tone on the same page, specially for Beolab 5 owners!

Best regards,

Steve.

The file doesn't download properly! Or at least it doesn't on my Mac!

Should we be wary of power levels? - you ear is less sensitive to lower frequencies and so to hear a constant volume from a low frequency signal the amp will likely have to turned up (assuming the input signal is constant amplitude and your speakers are actually capable of reproducing it).

I can't download the file ....

Steve can you attach file here somehow ?

Well using a different test cycle, Beolab 3s do 40Hz no problem but cannot do 30Hz. Interestingly, CX100s via a BM5500 do 30Hz rather better!!

peter can you send me this file via email ?

nmartin@sbb.rs

I manage to play it somehow...

And my BL8000 goes to 30 I think ... which I think is ok!

Hey Steve,

I've been wondering the same thing regarding my MS150 speakers. The only problem I can see with with playing a sine wave through your speakers and subjectively reporting the outcome is in the case of distortion. With little tiny 4" bass drivers, when you send 30 cycles into them, they probably aren't reproducing too much of the fundamental, but instead, are generating harmonic distortion, so you hear lots of 60, 90, etc. Hz overtones instead. It's the same principle as say, your car stereo, which probably has a bass control which alters the frequency at 100Hz. You aren't really getting deeper bass, and aren't getting louder deep bass, but the greater quantity of 100Hz makes it seem as if you are. Until you actually measure the output of the deeper bass, that is.

Jon

toyteg08:

Hey Steve,

I've been wondering the same thing regarding my MS150 speakers. The only problem I can see with with playing a sine wave through your speakers and subjectively reporting the outcome is in the case of distortion. With little tiny 4" bass drivers, when you send 30 cycles into them, they probably aren't reproducing too much of the fundamental, but instead, are generating harmonic distortion, so you hear lots of 60, 90, etc. Hz overtones instead. It's the same principle as say, your car stereo, which probably has a bass control which alters the frequency at 100Hz. You aren't really getting deeper bass, and aren't getting louder deep bass, but the greater quantity of 100Hz makes it seem as if you are. Until you actually measure the output of the deeper bass, that is.

Jon

Interesting point

Be wary all of ye who attempt to draw conclusions from what you hear (or worse still think you hear)

http://en.wikipedia.org/wiki/Equal-loudness_contour

What's crucial isn't whether you are able to detect a pulse at the various frequencies, but whether that pulse generates enough sound pressure for the bass reproduction to be precise.

I've run my BL5s from 10Hz all the way up to 1000Hz, and while I can actually hear a pulse beginning at around 13Hz, the Sound Pressure Level (SPL) isn't at the appropriate plateau before 20Hz.

Hi Guys,

Thanks for all your comments - I knew this would spark some debate!

I agree that any listening tests of this nature need to be taken with a BIG pinch of salt, due to many factors, including the psophometric contour (the inability of the human ear to hear bass at low levels), room acoustics, active bass equalisation (on some Beolab speakers) and more.....  However, I think that some interesting points can be deduced from this test track:-

1) If you play the track at a slightly louder than normal listening volume, you will reduce the "bass deafness" of your ears without risking damage to your speakers.

2) At each frequency, listen for the second long tone and note the last frequency at which this is similar in volume to the tones before.  Whilst the volume drops gently for successive tones, you are mainly hearing the difference that your own ears perceive in the bass levels at different frequencies.  This will normally drop away suddenly at one pitch; this is the point at which your speakers have failed to reproduce the note efficiently (ie. the lower limit of their effective frequency response).

3) Some indication of "room modes" (ie. frequencies where your room acoustics interferre with the music) by raising the volume between the 350Hz and 150Hz sections and listening for "boomy" notes which seem to echo or reverberate.  Any particular problems here are worthy of further investigation, as they may be affecting all the music that you listen to......

4) Remember that these tests are not scientific, however I think that they still have value and help to improve awareness of music and acoustics

For information, I tried these tests with CX50's and found that 80Hz was the last point at which the test tone was clear and of similar volume to those preceding it.  With RedLine 60's, this point was reached at 40Hz.  In both these cases, these figures do closely match the quoted bass extension frequencies, so with careful use I think these tests can still be quite accurate.

Please let me know what you think!  By the way, I'm not sure how to attach the MP3 file on the forum, but I'm happy to email it to anyone who asks (file size is 462Kb)  The link to the file again is (look for the question about bass response):-

http://soundsheavenly.co.uk/faq.htm

Best regards,

Steve.

Steve.
I have tried your MP3 with various speakers and amps, but only briefly.
The 'speakers' which I could hear the lowest is....

A8s!
Being able to hear low, doesn't count the same as being able to move lots of air then, does it?

My Beovox 5000s (60s version)  make the glasses rattle in the cupboards, to sounds I cannot even hear on your MP3.
Will make some detailed observations over the weekend. Cheers!

Andy T.

Jandyt:

Steve.
I have tried your MP3 with various speakers and amps, but only briefly.
The 'speakers' which I could hear the lowest is....

 

 

 

A8s!
Being able to hear low, doesn't count the same as being able to move lots of air then, does it?

My Beovox 5000s (60s version)  make the glasses rattle in the cupboards, to sounds I cannot even hear on your MP3.
Will make some detailed observations over the weekend. Cheers!

Andy T.

 

 

 

 

 

 

Sealed Headphones can be very good at bass as it it "pressure" that counts, speakers, unless in a controlled enviroment, are less "certain". Conversley speakers are better at high frequencies because of the front on planar wave effect (and how your ear flaps interact). Headphones give a false impression of stereo higher frequenicies.

As an interesting experiment, if you have an audio editor, or something such as Winamp, download an HRTF (head-related Transfer Function) plugin. This modifies a conventional stereo audio file to model your head density, time delays between your ears etc. (please read up for more info). The net effect is to make a stereo audio file sound like listening to speakers while actually listening through headphones (when listening to speakers you never get that "middle of your head" sensation you get with centre mixes if you listen with headphones).

On the other hand you could just listen to the music

Puncher:

As an interesting experiment, if you have an audio editor, or something such as Winamp, download an HRTF (head-related Transfer Function) plugin. This modifies a conventional stereo audio file to model your head density, time delays between your ears etc

punch, that is really interesting! i think i might have a play with this. however, how might i use "Is Null" in the head density calculation?

burantek:

Puncher:

As an interesting experiment, if you have an audio editor, or something such as Winamp, download an HRTF (head-related Transfer Function) plugin. This modifies a conventional stereo audio file to model your head density, time delays between your ears etc

punch, that is really interesting! i think i might have a play with this. however, how might i use "Is Null" in the head density calculation?

Ask Andy I believe he's already sussed that out!

as well as the file that Steve has kindly supplied, there are 3 very useful WAV files to get hold of and burn to a test CD for this sort of thing....

1) the Matrix Reloaded soundtrack #3 - Reload by Rob Zombie  -  there is a bass run down of about 40 seconds that goes clear down to 20hz

2)  the Telarcs 1812 Overture, the one with the big cannons going off, impressive on the right amp/speaker setup

3) if B&O are claiming that they have a system that goes down to 12.5kz, then the ideal sound track to test that theory is on the Ani Difranco CD called "To The Teeth"  track 13 titled  "I know this bar" 

I know that REL ( a big sub woofer manufacturer ) have this track in their workshops, and I quote

"a customer complained about his REL Strata 5 sub when listening to an Ani Difranco CD, it started popping on every 3rd (slightly louder) beat of the 13th track titled "I know this Bar". The SPL meter registered 70db C weighted in his listening room, this is a moderate volume, so we feel the complaint justified.  The volume of the pops was about the same volume as the music being played. The Ani Difranco track we had problems with was reading almost flat from 63hz down to 12.5hz measured at the seating position. It turns out that this is one of those rare legendary "system killer" recordings. If you have a system that genuinely goes down to 13 hz then this recording will be a major headache unless you have huge headroom in the amplifier. The REL tech guys played the track and straight away the pops started, the amp was clipping, they then fed it test tones at 13hz and the amp ran flat out of steam and control, we know the REL sub has enough in the driver to deliver 13kz test toneswith correctly specified amps,  but the demands were simply too high for the customers xxxxxxx 150w amp"

NB  xxxxxxx being the manufacturer of the amp, which REL do not want to disclose.

Steve at Sounds Heavenly:

If you play the track at a slightly louder than normal listening volume, you will reduce the "bass deafness" of your ears without risking damage to your speakers.

Please let me know what you think!  By the way, I'm not sure how to attach the MP3 file on the forum, but I'm happy to email it to anyone who asks (file size is 462Kb) 

Hi Steve,  do you have a WAV file for this experiment -  rather than an MP3 file, if you do can I then d/load it from your website, then I can put it on one of my test CD's and take it to the local B&O shop in St Albans

You could always try HERE

nice site, duly d/loaded all the Wavpack tracks 43mb

many thanks

Nice one Puncher!

The baby's in bed at the moment, but I will download these ready to try out in the morning once she's woken up.

Best regards,

Steve.

Running a full sweep on the monitors on my desk at the moment shows they peter out at a measly 45 Hz, wheras the Genelecs I was using the other day responded down to 25 Hz (which is exceptional for a compact speaker).

BeoLab 9s, the BeoLab 2 and obviously the BeoLab 5s will reproduce 20 Hz without any difficulties. I know BeoLab 5s go considerably deeper too.