Hertz Meter Reading Device

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

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

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