Hertz Meter Reading Device

In the famous lyics of F. Sinatra, "you can't have one without the other".....

Bob

These are called SPL meters where you can set up the frequency you want to measure the SPL in dB.
If you STILL want to only measure in Hertz than refer to the first post.

It is meaningless to ask "how low it can go" without specifying some number of db that the spl has declined by, relative to the response at some reference frequency (say 1kHz).

A common way of specifying bass rolloff might be something like it is down 3db at 30Hz, relative to 1kHz, and rolls off at 12db/octave below 30Hz.

If you are asking if there is a meter that will tell you at what frequency the response is down by some number of db, the answer is undoubtedly no.

Regards,
-- Al

As the frequency gets lower, you'll notice the volume decreasing as well. There will be a point where the tone is no longer audible. You have just experienced the bass roll off of your system.

As well as the roll-off of your ears, of course, Bob, which may very well be more significant than the system roll-off which you are trying to determine, unless the tones are played at extremely loud volumes. Remember the Fletcher-Munson effect.

Regards,
-- Al

My gripe about frequency response specs is that they ought to be measured not only relative to the SPL level at 1000 Hz, but also AT some particular SPL level at 1000 Hz. If the SPL is very low the woofer will not run out of excursion and the LF performance will be better, but unfortunately you won't be able to hear it :-(

Response to 11 hz does NOT mean you have useful bass (not base) to 11 Hz. That number is probably down by 20 dB, practically inaudible relative to higher frequencies. Are there recordings that go below 20 Hz?

Most subwoofers start rolling off at 30 Hz or higher with a 24 dB per octave slope. By the time they get to 25 they could be down by 6 dB or more. They may also produce gross amounts of 2nd harmonic distortion. Taking the Fletcher-Munson hearing curve into account, we'll hear the harmonic more than the fundamental.

There may exist frequency meters, but as stated above, all you need is a test CD, an SPL meter, AND the response curve of the meter to correct your readings.

You'll have to place the mic or meter right up to the sub's cone(sealed) or port. Otherwise you'll only be measuring how the sub interacts with your room.

What you're looking for is called a 'Real Time' or 'Audio Spectrum' Analyzer(http://en.wikipedia.org/wiki/Real_Time_Analyzer) You can get software for a computer now that will enable you to analyze the SPL output of your speakers, in your room, at all(what are considered) audible frequencies:(http://www.trueaudio.com/rta_faq1.htm) Another very affordable method is the 1/6th octave RTA that the Behringer DEQ2496 provides(http://pro-audio.musiciansfriend.com/product/Behringer-DEQ2496-http://cgi.ebay.com/B-K-SINE-SQUARE-WAVE-GENERATOR-MODEL-E-310B_W0QQitemZ130323305278QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1e57dfd33e&_trksid=p3286.m20.l1116UltraCurve-Pro-Mastering-Processor?sku=182484) The low freq cutoff for most RTAs is 20hz though. A greater problem of getting accurate measurements at the lower freq is the response(below 100hz) of most "calibrated" microphones. Mics that are actually accurate at the freqs you are interested in are expensive, and the testing device you are using has to accept the correction curve data of the mic. ie:(http://www.earthworksaudio.com/27.html) (http://www.linearx.com/files/pdf/M51_Mic_Brochure.pdf) To test for output at 11hz; you'd probably need a signal(sinewave) generator like this(http://cgi.ebay.com/HEATHKIT-AUDIO-GENERATOR-MODEL-G-2-SINE-AND-SQUARE-WAVE_W0QQitemZ160355544791QQcmdZViewItemQQptZBI_Signal_Sources?hash=item2555ef6ed7&_trksid=p3286.c0.m14) or this (http://cgi.ebay.com/B-K-SINE-SQUARE-WAVE-GENERATOR-MODEL-E-310B_W0QQitemZ130323305278QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item1e57dfd33e&_trksid=p3286.m20.l1116), an SPL meter(which again will have a mic that's inaccurate at low freqs) and a volt meter so you can be certain you are remaining consistant in your signal between your reference freq and the freqs for which you are testing. Hook the generator up to one of your preamp's inputs(with the voltmeter across the +/- outputs for calibration) and test away. There are many signal generators(more expensive) that have built in voltmeters BTW. The low freq cut off for Redbook CDs is 20hz, and there's VERY little on vinyl, outside of some direct-to-disc pipe organ music that even goes down to 16hz. You won't hear anything at those sub-bass freqs, but the visceral effects are fun.

It is not how high/low the speakers can go, it is how high low the 'room' can go. When you do measurements it is the combination of the two that is being done.

Ojgalli,
Saint Sans organ piece goes to 16hz. A recording of it comes as part of the 'demo' disk with my sub.
I played it 1x and it is scary. Whole house rumbled, plates rattled and you could see the window reflections vibrate.
So yes, there IS music that goes that low, but so low that unless you just gotta have it, there is almost not point.
And I played it 'safe' not turning it up near to 'normal' listening levels.

I have a test CD (CO-75046 put out by Denon) which has tracks at 4, 8, 17, 31, Hz, and up. I think that the lowest tracks are for use with electronic test equipment.

My subwoofer cones do respond at 8 Hz, but I hear nothing, which is not surprising. At 17 Hz I feel something, but I wouldn't call it hearing. It is this felt sensation that gives realism to some pipe organ music, and I have some music recordings that you definitely feel in your stomach.

Hi Bob,

Those are logical questions, and the answer to the first one is that if the system reproduces the music in a neutral manner, with flat frequency response, then the ear will hear it similarly to how it would have heard the original live performance. If the system were set up to compensate for the Fletcher-Munson or other "equal loudness curves," the perceived sound would be very imbalanced because the hearing process in real life has no such compensation.

That assumes, of course, that you are listening at realistic volume levels. Some compensation may be in order if the listening volume is unrealistically low, which is why low-fi and mid-fi receivers sometimes include a "loudness control," which does just that. Of course, with that type of equipment one will often tend to want to listen at less than realistic volumes, because their distortion will be both greater and more objectionable at higher volumes.

Rodman has provided some good information about how to do it right, and about the complexities that are involved, and ElDartford and Buconero have made excellent points about sensitivity to level and to room effects.

Re level matching by ear, I have no experience trying to match satellites and subs, because my speakers are pretty much full range, but I would think that using test tones would at best provide a rough starting point, with the final adjustments having to be made using well-recorded music that contains significant deep bass content.

Regards,
-- Al

If I set a sat's level to be 85dB, by SPL meter, at 1K Hz and then set the sub's level to be 85dB at 40 Hz, why don't we attempt to compensate for the loudness curve and set the level higher than 85dB so the perceived level matches not the measured level?

Ideally you want your system to respond close to flat and then tilted slightly towards your room and personal tastes but still primarily so as to reproduce what is on the recording.

It is usually the job of the Mastering Engineer to decide how to balance the sound. Soft pieces tend to be mastered bass heavy to compensate for the usual fact that they are played back at modest volumes whilst heavy rock may be mixed bass light so that it can be cranked.

Examples:
Owner of a Lonely Heart - Yes - is designed to be cranked
On Broadway - Weekend in LA Live George Benson - is designed to be cranked
Killing Me Softly - The Fugees - is designed to be played more softly and has heavy bass.
Happy Coat - Osabe Trio with Ray Brown on bass - is designed to be played softly as it has heavy bass

FWIW: 100 db is about optimum flat as far as our hearing sensitivity goes and the biggest change is in the bass where extreme LF goes from being barely audible at 70 db SPL to loud at 110 db SPL.

This whole issue is clouded by the fact that most speakers compress badly when you exceed 95 db SPL at 2 meters (typical istening spot). This can ruin many otherwise excellent recordings that were meant to be cranked - as the dynamics is all lost in the BBQ temperatures inside the woofer/midrange voice coils.

>Rodman99999 said:
>The low freq cut off for Redbook CDs is 20hz

This would seem to be a misunderstanding.
As other have posted, there are test CDs that provide signals under 10 Hz.

Maybe you were thinking of the upper limit of 44/16 being around 20 KHz?

Fab4- The IEC standards on Redbook CDs included the frequency response of 20-20kHz. Read under, 'Technical Details' on this site(click on 'Red Book Audio CD Standard', bottom of page): (http://tripatlas.com/Red_Book) Like most other things in this hobby; nothing is set in stone, and while most Redbook music CDs are recorded with the freq below 20Hz filtered out, there are some out there engineered with info below that(mostly test/tech CDs). Note what are cited here as the lower freq response limits of CD and SACD: (http://www.answers.com/topic/super-audio-compact-disc), under 'Overview'.

Rodman99999,

Apparently I misunderstood what you were saying about "cut off". So sorry!

With a constant 20 Hz test tone, directly off a computer, and a truly capable subwoofer, you won't hear anything but rattling and it makes you nauseous within a minute. How's that for a meter? Good chance you'll be crying about the blown drivers before you toss your cookies.

I REALLY should have chosen my words more carefully there. Happy listening!!

Thanks Al & Shadorne. The point I was sort of alluding to is that it seems to me that attempting to do level matching by ear, we would end up with the sub's level set too high. Thus, the sub would call attention to itself and/or sound boomy.

Yes, now I see what you were saying in your second question, Bob. But I think that my previous answer still stands. Test tones would give that result, to the extent that perceived equal loudness can be judged accurately between a 1kHz tone and a 20 or 30Hz tone. Unless, that is, the tones are played so loud that the "perceived equal loudness curves" become flat, within the bandwidth of the sub, but I doubt that anyone would want to listen to a pure 1kHz sine wave played that loud.

But music would not give that result, because what would be judged would be the timbral accuracy of the instruments, and the settings that result in best timbral accuracy, definition, etc., presumably are those that place fundamentals and harmonics in proper balance, which presumably is what would correspond to measured flat frequency response.

Regards,
-- Al

11 Hz ? lol At that point you need more like a siesmagraph.
(don't put cracks in your foundation when trying this).
(what source material do you have that has 11 Hz signal?)

You might try to rent or buy a spectrum analyzer, but I don't know how low they go.