Questions on Allen Speakers

[SDS93]

I was just thinking, on...say an Allen HR-100 speaker pair, the sound frequency response is 40 Hz to 20 kHz according to the Allen website. I have learned over the course of several weeks that at least 32 Hz is needed for a low C '16 pipe. I know that on my current home organ (MDS-5), the '16 stops are audible and sound really very good. Even on low C on the pedal. So is 40 Hz good enough for some organ installations? It sure seems to be here, anyway. I know that the room is small. It must be less than 250 sq ft. I'm just curious about this. I know Allen also makes subwoofers and bass cabinets as well, so the HR-100 must be mid-range I'm guessing. And I thought I was told by someone somewhere that the HR-100 pair would handle 32' stops too. I'm seriously beginning to doubt that however, even though they sound just fine handling the 16' stops.

In short, my question is...are these HR-100 speakers an exception to the "rule" that says a 16' stop needs at least 32Hz?
(Sorry if I sound like a bumbling idiot; I barely know what I'm talking about when it comes to sound science. Lol).

--Stephen

[myorgan]

In short, my question is...are these HR-100 speakers an exception to the "rule" that says a 16' stop needs at least 32Hz?

Stephen,

The quick answer is, "No." You're probably hearing the 1^st and 2^nd partials of the overtone series, which will trick your ear into thinking it's actually hearing the fundamental tone.

To discover more about the topic, search the Forum for the following topics: Resultant, or Subwoofer. There is a ton of information here about the topic-in fact, one thread lasted 6 pages before it FINALLY died!

I hope that helps get you started.

Michael

[SDS93]

Thanks for the info!
--Stephen

[toodles]

Speaker frequency response measurements are pretty much useless unless they come with a tolerance in dB; i.e., 40 to 20 kHz +/- 3 dB; any speaker's response rolls off (rather than cuts off) and bass response is very much influenced by room response and placement within the room.

The "virtual bass" that Myorgan mentioned is where the ear hears the frequency relationship between some harmonics, and infers the fundamental. It is just the way the ear works. But, in addition, you are probably hearing some true 32 Hz response though it might be reduced in volume from the pass band.

[jbird604]

While surely no reputable organ dealer or installer would use HR-100s or other smallish organ cabinets (from Allen or anybody) as the only speakers in a normal church-size installation, that doesn't mean they won't work in a HOME setting or even in a very small chapel or studio. In a church setup, HR-100s are only used for manual-only channels, or to supplement the larger HR-200s when more dispersion is needed.

As toodles points out, bass response doesn't just "fall off a cliff" at the advertised cut-off frequency (but I'll mention an exception to that below), but it usually rather smoothly tapers off. Also, the perceived level of bass is greatly influenced by the size and characteristics of the room.

For example, in an automobile there are often speakers no bigger than 6" (or possibly 8" or even 10" in a super deluxe setup), yet we usually perceive bass response to be more than adequate, often overpowering, in a car. (And I'm not even referring to the rolling boom-boxes with massive speakers in the trunk or somewhere that produce seismic bass as they drive around the neighborhood in the wee hours.) But a mere 6" woofer can make big bass inside a car because the volume of air it acts upon is quite small compared to a typical living room or church.

So in a home, the HR-100 (or the HC-13 or some other Allen designs with only a 12" woofer instead of a 15") might be good enough, at least at reasonable listening levels. Placed in a corner or at least next to a wall, a 12" woofer can generate quite a bit of bass, especially if the room is friendly to bass, with some smooth hard surfaces.

As to "falling off a cliff" -- yes, a tuned vented speaker enclosure can have a definite point below which the output really does go to nearly zero. That's due to the behavior of a vented box -- at the tuning frequency of the port/box combination there is an increase in output, but below that frequency the rear wave of the woofer cone is essentially un-baffled and thus cancels the output from the front of the cone. I don't actually know the tuning frequency of the HR-100, but it's probably down below 32 Hz. Otherwise the voicers would have to deal with an audible hump in output when voicing the bottom octave of manual 16' stops.

So I'm thinking you probably DO hear a good deal of real 32 Hz output on the low C of your pedal stops. Your MDS-5 of course has a bass control for each output channel in the cage, so when it was voiced the voicer presumably would've added a little bass boost if necessary to bring out the bottom octave with the HR-100 speakers.

[michaelhoddy]

Having experience with the HR-100 personally on my former organ- they're fine for a 16' manual reed and maybe a manual 16' flue where the bottom octave response is not critical or where the stop has a lot of 2nd and 3rd harmonic development, but there's no way you'd be happy with them as a primary pedal cabinet, even in a small room.

[John Vanderlee]

We have an ADC3160 in our home with four HC 13's on it.(maybe it was HC11, but the woofer is 12” in a ported enclosure) My wife - the musician- complained of the lack of fundamental at 16' low C- 32 Hz. I added a sub bass channel with 15” driver and out board amp. The difference was incredible.

[SDS93]

Interesting information, everyone! Thanks for your time in explaining. I'll admit, a lot of this stuff goes over my head, but I'm happy to know that there is plenty of information on this forum. I will slowly but surely learn about all this!
Another thing that prompted the question was that I am looking at eventually (later than sooner due to funds), improving the separate speaker system I have on the Hauptwerk portion of the organ. I am gathering that the bookshelf Zenith Allegro 1000 speakers (ca. 1973) I am using are not optimal for VPO use. From what I've read so far, bookshelf speakers are inferior to studio monitor speakers which I may save up for later. But that may or may not have anything to do with frequency output; it sounds like it's more of a dispersion issue.
I've always really enjoyed the "presence" of real pipes on the Allen's voices, so I am certainly happy with the HR-100 speaker pair. While the Hauptwerk voices are incredibly realistic, that as well serves as the problem. I feel like I'm playing a CD, or radio, or TV. The sound lacks presence. You can tell it's not in the same room I am in, and that's certainly not Hauptwerk's fault, rather the speaker set up is to blame. I agree with what jbird said on a previous topic that Hauptwerk is usually always great with headphones. I'd try that, but I like to make the floors shake. Haha!
ANYWAY...I know that last bit didn't have much to do with anything. Sorry.
Point is, I appreciate all the knowledge you all have with my questions regarding speaker frequency. Particularly the HR-100s. I'm learning a lot! That being said, I will probably never be able to wrap my mind around some of the really nitty-gritty concepts, but will certainly try! :)

[myorgan]

I'm sure you're thinker than you're smart (spoonerism-in case you didn't already know). You can figure it out-just give it time.

Michael