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Subwoofer comments please

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peterorg

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Subwoofer comments please

PostMon Jan 03, 2022 4:18 pm

I have a basic 2-speaker stereo Hauptwerk audio setup which I have used for some 10 years and have been very happy with, though I do envy all the multi-channel-speaker setups of some Hauptwerk users! I have been considering purchasing a subwoofer to supplement my basic setup and one which I like the look of is the Wharfdale Diamond SW150:

https://www.amazon.co.uk/Wharfedale-Dia ... C82&sr=8-3

I have read various opinions on the best way to implement one of these in a basic stereo setup, not just on the Hauptwerk forum but on many audio / HiFi websites.

Some advocate simply using it “In-line” and setting the crossover frequency to a suitable value so that the subwoofer reproduces the low bass sounds rather than the stereo speakers, but this allows the stereo speakers to reproduce the harmonics of the bass sounds the subwoofer is unable to.

Others advocate routing the 16’ and below ranks via a separate audio channel to the subwoofer.

I wonder if anyone who actually uses a subwoofer in, perhaps, a similar situation to mine has any views on the best way to go, please.

Many thanks, Peter
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mnailor

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Re: Subwoofer comments please

PostMon Jan 03, 2022 6:35 pm

I'm a little concerned about the SW150's listed frequency response of 35 - 110 Hz, without the usual +/- 3 dB or other attenuation bound stated on the manufacturer's site. Maybe that info is somewhere -- I didn't find it.

That only goes down to between 16' D and Db. A good organ sub should at least go into the 32' octave, even if it doesn't make it all the way down to 16 Hz (32' C). If 32 Hz is well within the sub's range, then your ear can be fooled that 32' stops have some fundamental because their octave harmonic is strong. My sub goes to 16 Hz at -3 dB, but even the 16' C's sound pressure can be felt.

As far as routing, with 2 main speakers you do have the option to pass the stereo signal through the sub, assuming it has a high pass filter and stereo outputs, but the more expandable approach is to route ranks to main speakers and send a mixdown of all your mains to the sub, setting the sub's low pass filter and slope to not overlap too much of the main speaker's bottom range or leave a frequency gap uncovered.

There is no sound improvement to be had by passing the signals through a sub on the way to the mains, and maybe a loss since sub inputs and/or outputs may be unbalanced. Hauptwerk can do the mixdown unless you're on Lite or HW 4.

NOTE: I found a picture of the back. It has unbalanced line outputs and inputs, so inline would work as long as you only have 2 main speakers, but balanced would be better.
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IainStinson

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Re: Subwoofer comments please

PostMon Jan 03, 2022 6:57 pm

I also send a mix of all my outputs to a separate audio channel and send this to my sub. I adjust the sub’s crossover to work appropriately with my other full range speakers.
Iain
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mdyde

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Re: Subwoofer comments please

PostTue Jan 04, 2022 4:21 am

[Topic moved here.]
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.
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Romanos

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Re: Subwoofer comments please

PostTue Jan 04, 2022 8:16 am

Some advocate simply using it “In-line” and setting the crossover frequency to a suitable value so that the subwoofer reproduces the low bass sounds rather than the stereo speakers, but this allows the stereo speakers to reproduce the harmonics of the bass sounds the subwoofer is unable to.

What happens when you have an "in-line" sub is that everything above the crossover still goes to the speakers, and everything below goes to the SW. This is a GOOD thing, because the smaller speakers are ill-equipped to deal with those uber low frequencies. If you do not attenuate the signal in that uber low range, then they will still try to make the sounds, even if they cannot or only do so poorly. By having a crossover point, they don't even try, so the drivers are left with an easier load and typically do better with it. All that to say, by using this method, you will NOT be loosing any harmonics, as they occur much higher in the frequency spectrum, and therefore those harmonics will still come out of the regular monitors. The subwoofer will simply take the bottom octaves (fundamental, essentially).

I also echo that you'd want to shoot for a sub rated to at least 32hz (even at -3db) as that is low C of a 16' rank. The 32' octave is nice (fun) but not necessary, strictly speaking.
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mnailor

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Re: Subwoofer comments please

PostTue Jan 04, 2022 8:26 am

All of my 4 speaker models (active monitors) have a low cutoff to ignore frequencies below their safe range. I didn't know you could buy speakers with no rumble suppression!

Still, with 20 mains, in-line subs aren't an option.
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Romanos

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Re: Subwoofer comments please

PostTue Jan 04, 2022 8:28 am

True. That's where the built in roll off controls that you have come in handy.

I sold my sub last year after our daughter was born (I couldn't ever use it with an infant sleeping in the house and I needed the funds for another project) but I used to run a mix-down of the whole organ and feed the sub that. It worked a charm.
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matbruce

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Re: Subwoofer comments please

PostTue Jan 04, 2022 12:00 pm

Surely when buying a subwoofer the lowest frequency should be no less than 20Hz.

Looking at the microphones used by sampleset producers, which at the high end is generally a mix of Neumann large and small diaphragm condensor microphones. The frequency response on these microphones is 20-20,000Hz.

There is definitely something to be said of subwoofers which can produce the cleanest signal at around 20Hz and that seems like something to strive for when buying.

However...
I'm not entirely convinced that a sub with a frequency response <20Hz is actually worth buying, given that the sample is not going to have any recorded samples <20Hz.

Would welcome other thoughts....
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Romanos

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Re: Subwoofer comments please

PostTue Jan 04, 2022 12:04 pm

There is definitely something to be said of subwoofers which can produce the cleanest signal at around 20Hz and that seems like something to strive for when buying.

However...
I'm not entirely convinced that a sub with a frequency response <20Hz is actually worth buying, given that the sample is not going to have any recorded samples <20Hz.

Well of course it's lovely to get a sub that can handle these lowest frequencies. The problem is that bottom octave is really where the price begins to ratchet up. You are right that most recording is the 20-20k range (and many interfaces have this limitation as well).

No doubt, having a sub that can reach all the way down is the best bet; having headroom is never a bad thing; it means that the sub can do the rest very competently, and isn't struggling at the very edge of its range to do the more basic stuff like 16' stops. I'm sure, too, that there is something to be said for having a sub that can produce more of the lowest fundamental tones (or even imply them) than those that cannot. But again, you have to do a cost-benefit analysis here.

Lots of subs got to 25ish hz. There aren't nearly as many that reach those extra few down to 16hz.
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TubaFan

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Re: Subwoofer comments please

PostTue Jan 04, 2022 10:03 pm

You will most likely have to spend a bit more money to get a sub that is worth using with Hauptwerk in your home. Performance down to 16 Hz certainly is much more important in a space where the sound wave can fully form, but I'd try to find one a bit lower, at least into the 32' octave.
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matbruce

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Re: Subwoofer comments please

PostWed Jan 05, 2022 10:10 am

Again my point stands.
Why would you spend a lot more money for "headroom" when your sub will never play a frequency below 20Hz given that the rate-limiting factor is microphone frequency response rather than the subs frequency response.

Seems like people will spend an awful lot of money on subs going down to 16Hz unnecessarily without considering these fundamentals first?
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TubaFan

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Re: Subwoofer comments please

PostWed Jan 05, 2022 10:28 am

matbruce wrote:Again my point stands.
Why would you spend a lot more money for "headroom" when your sub will never play a frequency below 20Hz given that the rate-limiting factor is microphone frequency response rather than the subs frequency response.

Seems like people will spend an awful lot of money on subs going down to 16Hz unnecessarily without considering these fundamentals first?


I just checked the microphones used to sample Peterborough Cathedral, the main sample set I am using, and one of them goes down to 3Hz. I haven't bothered to see if any of the others they used go that low, but was curious after your comments to see if they had anything in that range.

Microphone used: https://earthworksaudio.com/omni-microphones/qtc40/

I haven't been able to find much information from other sample set producers, but I'm sure many of them also use microphones that go below 20Hz.

I assure you that the subwoofers in my church definitely are producing plenty of 16Hz fundamental when I hit low C on the 32' stops with Peterborough. :D
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IainStinson

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Re: Subwoofer comments please

PostWed Jan 05, 2022 12:23 pm

A 16hz sound wave is about 70ft long. Do you need to relate the size of the space in which you are listening and the wavelength of the lowest fundamental you can hear in the space? Can the wave fit into the space? (Sorry about using imperial units).

Perhaps it is sensible to consider the listening space dimensions when looking for an appropriate sub.

Iain
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josq

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Re: Subwoofer comments please

PostWed Jan 05, 2022 2:13 pm

IainStinson wrote:A 16hz sound wave is about 70ft long. Do you need to relate the size of the space in which you are listening and the wavelength of the lowest fundamental you can hear in the space? Can the wave fit into the space? (Sorry about using imperial units).

Perhaps it is sensible to consider the listening space dimensions when looking for an appropriate sub.

Iain


I guess there is a little misunderstanding here.

Because if you wear headphones, there is only a few cm of room between the earcup and the ear. Only frequencies above 10000 Hz or so fit in such a small room.

Yet headphones are clearly capable to reproduce even very low bass. So it seems that room size has little impact on what frequencies can be reproduced.
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TubaFan

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Re: Subwoofer comments please

PostWed Jan 05, 2022 3:23 pm

Headphones aren't producing sound in the open air though. In a small space, having a subwoofer that goes down to 16Hz isn't that important, but the product mentioned above doesn't seem like a good choice to use for low organ bass. There are plenty of subs that get much lower that aren't too expensive. It just gets much more expensive when you chase the 16Hz mark.
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