No. To accurately test the response of your system, you need either RTA software and a calibrated micrphone, or a test CD or DVD with warble tones or 1/3rd octave band limited pink noise in conjunction with your SPL meter. I know of no such CDs or DVDs, but somebody else might on the forum.

Test CDs or DVDs with steady state fixed frequencies are absolutely useless in determining the frequency response of speakers since the room's acoustics will swamp any valid reading of the actual speaker.

There are moments, that happen with pleasant regularity in this Saloon, where many of the seasoned Gunslingers just hit it out of the park.

This discussion sheds light on a often oversimplified subject, and provides all the readers here a way to look at their own systems, and understand why some of the Gunslingers choose other means to the end.

The use of stereo subwoofers, and the benefits of a separate LFE channel have been suggested as significant system enhancements many times. This discussion seems to support those arguments. In response to this bass management problem, Soundhound's stereo subwoofer solution could be employed in many of our systems, even if we have passive crossovers. My own system is similar to his in this respect.

The use of a separate sub for the LFE channel seems to make a lot of sense to me also. According to some Gunslingers, the majority of multi-channel audio recordings use the LFE channel as a bass booster, which creates double bass issues that might even be made worse yet with the bass management limitations discussed in this tread.

Thank you all for your contributions...

Allan

P.S.: The Stereophile Test Disk No. 3 has warble tones at 1/3 octave centers that I have used with some success, but a RTA is the best way to go. If you have a friend with the equipment and software, it can be done pretty easily. The next question is what do you do with the information...

Scott

All you need to do is listen by ear; tune everything to the way you want hear. If your current system sounds good to you, then it is the best and leaves it that way.

Friendly reminder: while the behavior of the acoustic combination of signals is somewhat different than the combining of electrical signals, mostly due to the effect of an acoustic environment and speaker placement, even if one manages to keep all bass individually isolated in several channels and reproduce them independently, loss and/or boost, similar to electrical combination of signals, will occur in the listening environment as the sound waves interact.

Some would say that environmental acoustic interaction is better than electrical, somehow more as ‘intended.’ I suppose that would depend on how the method of recording and/or mixing were done as a means of producing something ‘intended.’ Unless it were for a specific purpose, engineers generally seek to keep signals in phase on various tracks. If there is some small drift in phase, the lower the frequency, the less impact a slight phase shift has. The electrical combination of bass signals is not automatically a bad thing, especially if it allows access to the reproduction of low frequencies in a room via one or more subwoofers that would have otherwise been left unheard.

If one were listening via headphones, there would be minimal combination of signals prior to interaction/interpretation in the brain, and for a ‘live’ stereo/binaural recording, this might be close to ‘intended’ in the ears, even if it leaves out the feeling of tactile bass.

Personally, I like aural and tactile bass together.

Three speakers utilizing three 15” inch woofers with 97 DB output is lethal enough, man..... Surround and LFE won’t be needed. (for real.....)

I knew somebody would bring up this point, and in fact I was going to cover it in my original post on the subject, but here goes.......

Yes, there is in-room acoustic cancellation to some degree with stereo subwoofers, but if you read the lengthy post I wrote on the subject of stereo subwoofers, I mentioned that this acoustic mixing in the bass is exactly what happens in real life acousitic events. That's the whole point!

Bass is not mixed to mono and squirted through a single source in real life music heard in real acoustic spaces, but is all around you in random phase. Multiple subwoofers preserve this random phase relationship in the listening room, as picked up by the recording microphones.

When this acoustic mixing of multi-channel (or stereo) bass takes place in the listening room, it is sensed as enhanced performance space ambience due to the natural acoustic mixing of low frequencies, just as in the original performance space - this does not take place with mono summed bass which only contains peaks and dips with no directional ambience information being conveyed to the listener.

Bass phase interaction in the listening room matters, just like it matters with higher frequencies. Natural acousitic mixing of low frequencies makes recordings sound more live rather than "canned".

As far as recording engineers keeping bass mostly mono, well, this was a huge issue in the days of LP records which could not tolerate out-of-polarity bass signals in the grooves. This condition would result in vertical modulation of the groove which could cause the stylus to leave the groove and skip to ajacent ones. Great pains were thus taken to record with bass as mono as possible. As a further precaution, all LPs were cut with the bass frequencies below around 300Hz blended to mono before being cut into the master laquer record.

This is not an issue with digital delivery media and bass can be as random phase as any other signal.

In my work on scoring stages where music is recorded (and in studios before that), I know personally that engineers now days give little thought to keeping bass mono. It is just not a concern anymore. In the recording of popular music, bass will tend to be more mono simply because most insturments (including the sole electric bass) are almost always recorded with single microphones, onto single tracks on (increasingly) digital audio workstations.

Recordings (like the organ demo CD I recently circulated) that were recorded with spaced omni-directional microphones contain large amounts of random phase bass information, which contains the low frequency ambience that all real world rooms posess, in addition to the bass directionality from low frequency instruments distributed in different parts of the recording stage (bass drum, contra-bass, timpani, organ pipes etc).

Preserving these low frequency cues in playback in the listening room adds to the sense of hearing a "live" acoustic event.

This dimention is totally lost when bass is summed in purely electronic form and sent to a mono speaker as it is with bass management.

I guess I didn’t have the time to express all my thoughts either, but I think within the wording I used in my last posting I did leave room for everything SH just said to be absolutely true. Specifically:

I run stereo subwoofers, using an ICBM between pre/pro and amp, with reasons as SH states. But I do not have eight subwoofers for absolute segregation of bass to seven respective full-range channels plus an LFE sub. So, in my setup, I experience some signal summing of bass before the bass is acoustically reproduced. I combine some of the signals electrically in order to not miss out on the bass in the channels for which I do not have an independent subwoofer while preserving a measure of bass differential that may exist between right and left in channels in a recording.

In stating that recording engineers generally wish to keep things in phase on each playback track, I did not mean to imply a continued practice of purposeful manipulation of the bass as was done for LP’s. I meant that, unless there is a reason to do otherwise, the original phase relationship of the original recording is maintained. In those recordings where a mono bass signal is distributed during mixing to two or more channels, a stereo sub setup becomes ‘dual mono’ playback. During playback where the original bass differential has been preserved or an induced bass differential exists, I’m glad I’m running stereo subs. Even if a stereo subwoofer setup does not exactly reproduce the original propagation of sound waves, in my perception a ‘live’ feeling is revealed. I have spoken in favor of stereo subs in the Saloon before. My enjoyment of SH’s organ recordings is enhanced by stereo subwoofers.