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Reproducing 32' bottom C

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Re: Reproducing 32' bottom C

Postby Gedakt » Thu Sep 02, 2010 4:25 pm

Eric - Are you referring to a commercially built active subwoofer or a subwoofer driver? If the former I, of course, agree as I mentioned. If you mean a DIY "driver in a box", which I was what I was referring to, then I cannot agree. My own system uses an 18" JBL driver in a 12cu.ft vented enclosure and performs wonderfully in a lounge room 28' long - but requires 9db lift at 16Hz for that vase-rattling, realistic result.

The use of a corner location will simply add to the problem of uneven response. Some notes will be enhanced, others diminished in volume. Ask any Hi-Fi expert about that one.

I should have mentioned that the voicing equalizer in Hauptwerk can be used to achieve the desired result, provided the speaker driver and amplifier can meet the additional demands. However if other VPO systems are also in use this solution is not practical. It is better to fix the shortcoming where is exists and thereby have a universal sound system which can also be used for CD reproduction, IMHO.

I am afraid my dB values were wrong in my original post. Where I stated "12, 18 or even 24dB/octave" this should have been "6, 9 or even 12dB/octave". And my reference to "tone controls" should have been "3dB/octave" - not 6. Sorry, I confused myself when converting linear ratios to dBs.

Max
Last edited by Gedakt on Thu Sep 02, 2010 6:07 pm, edited 2 times in total.
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Re: Reproducing 32' bottom C

Postby toplayer2 » Thu Sep 02, 2010 8:44 pm

Equilization devices can be effective to tame room modes, although in general they are not really very helpful to extend deep bass of a subwoofer system that doesn't have the ability on its own to cleanly provide powerful LF energy. It is easy, as Eric has asserted, to reach maximum excursion limits for the driver thereby causing severe distortion if one is fortunate or a blown driver if one is not as fortunate.

In my experience, subwoofers that can cleanly deliver 16 Hz at 100+ dB SPLs are few and far between and tend to be rather expensive. Perhaps extravagant for just a few notes, but the effect can be quite thrilling.

If one has a quality subwoofer and wants to neutralize at least some of the nodes/modes/eigentones caused by the listening room, this device was mentioned by Chris (OPUS1883) elsewhere on this forum. It has received some very impressive reviews.

http://www.tweekgeek.com/_e/DSpeaker/product/Anti-Mode-8033/Anti_Mode_8033.htm

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Re: Reproducing 32' bottom C

Postby Eric Sagmuller » Thu Sep 02, 2010 9:01 pm

Gedakt wrote:Eric - Are you referring to a commercially built active subwoofer or a subwoofer driver? If the former I, of course, agree as I mentioned. If you mean a DIY "driver in a box", which I was what I was referring to, then I cannot agree. My own system uses an 18" JBL driver in a 12cu.ft vented enclosure and performs wonderfully in a lounge room 28' long - but requires 9db lift at 16Hz for that vase-rattling, realistic result.

The use of a corner location will simply add to the problem of uneven response. Some notes will be enhanced, others diminished in volume. Ask any Hi-Fi expert about that one.

I should have mentioned that the voicing equalizer in Hauptwerk can be used to achieve the desired result, provided the speaker driver and amplifier can meet the additional demands. However if other VPO systems are also in use this solution is not practical. It is better to fix the shortcoming where is exists and thereby have a universal sound system which can also be used for CD reproduction, IMHO.

I am afraid my dB values were wrong in my original post. Where I stated "12, 18 or even 24dB/octave" this should have been "6, 9 or even 12dB/octave". And my reference to "tone controls" should have been "3dB/octave" - not 6. Sorry, I confused myself when converting linear ratios to dBs.

Max


Hi Max,

I was referring to passive subwoofers either commercial or DIY designs, generally of a fairly large volume. 6-12db is not so unreasonable though as long as the woofer excursion is in check. Your earlier figures I think is what alarmed me.

As far as corner placement, you are probably correct but the shape of the room also affects this considerably. The more common solution these days is to use multiple subs of a smaller size to help minimize room nodes.

The subs I have been considering building are nearly flat down to 20 HZ and then a couple db down at 16 HZ but with very powerful output, at least 110db. But they use very long throw woofers with low free air resonance so can handle the large excursions. Most woofers on the market just don't have the excursion needed and will bottom out with very much EQ added.
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Re: Reproducing 32' bottom C

Postby Gedakt » Fri Sep 03, 2010 2:46 am

Hello again Eric -

I think we are pretty well in agreement.

For those who may be confused, commercially made "active" subwoofers are those with an inbuilt amplifier incorporating the kind of equalization I decribed. I was referring to a home built subwoofer system. When I first tested my own DIY subwoofer (an 18" JBL in a 12cu.ft vented enclosure and associated amplifier) I was most disappointed until I researched the matter more fully and realized that equalization is essential. Without this the output at 16Hz was well down, even with the box correctly tuned. Furthermore, unless the equalizer slope is of a high enough order, the output at (say) 32Hz will be too high when that at 16Hz is adequate.

Regards,

Max.
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Re: Reproducing 32' bottom C

Postby Organorak » Mon Sep 06, 2010 6:36 pm

Does the reproduction of bottom 32 foot C depend too on the soundcard?

The specs for "cheaper" soundcards that are population with Hauptwerk users like the Maudio 1010 specify their frequency range is e.g. 22-20kHz. If the soundcard can't get below 22Hz it doesn't matter how good your sub is. THe only one amongst the recommended ones I could see that went low enough was the ECHO Audiofire 12 but it's a lot more expensive.

Thoughts?
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Re: Reproducing 32' bottom C

Postby oliver_mayes » Mon Sep 06, 2010 7:25 pm

My soundcard (E-MU 1616m PCIe) says 20 to 20 k hz, But has no trouble producing the 16 hz bottom note. I do have to boost the bottom 5 or 6 notes though.
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Re: Reproducing 32' bottom C

Postby wurlitzerwilly » Tue Sep 07, 2010 8:13 am

Organorak wrote:Does the reproduction of bottom 32 foot C depend too on the soundcard?

The specs for "cheaper" soundcards that are population with Hauptwerk users like the Maudio 1010 specify their frequency range is e.g. 22-20kHz. If the soundcard can't get below 22Hz it doesn't matter how good your sub is. THe only one amongst the recommended ones I could see that went low enough was the ECHO Audiofire 12 but it's a lot more expensive.

Thoughts?

Most of the specs err on the conservative side, to cover the manufacturer.
Usually a spec of 22Hz to 20KHz is meant to be flat across the range, but often the card will easily reproduce below 22Hz, although as Ollie has discovered, a boost of a few dB is often necessary to make the output response flat across the entire range.
With most of the popular ASIO cards, the extra EQ at the bottom end doesn't normally give rise to any untoward distortion.
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Re: Reproducing 32' bottom C

Postby organmad » Tue Sep 14, 2010 8:54 am

Just an idea, would Quad valve amplifiers not do the trick?

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Re: Reproducing 32' bottom C

Postby brooke.benfield » Tue Sep 14, 2010 1:54 pm

organmad wrote:Just an idea, would Quad valve amplifiers not do the trick?

Organmad


I'd have to say no. Valves (vacuum tubes, am I correct?) are a high impedance output type device and normally require a transformer to drive a low impedance load such as an audio speaker. By default, they will be less able to deliver high power to a speaker than silicon based amplifiers, which have no such troubles. Low audio frequency generation requires movement of large amounts of air and therefore, lots of power.
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Re: Reproducing 32' bottom C

Postby David Pinnegar » Thu Sep 16, 2010 7:26 pm

brooke.benfield wrote:
organmad wrote:Just an idea, would Quad valve amplifiers not do the trick?


I'd have to say no. Valves (vacuum tubes, am I correct?) are a high impedance output type device and normally require a transformer to drive a low impedance load such as an audio speaker. By default, they will be less able to deliver high power to a speaker than silicon based amplifiers, which have no such troubles. Low audio frequency generation requires movement of large amounts of air and therefore, lots of power.


Hi!

Yes - one needs to look at solid state amps which go down to DC. There was quite a fashion for such amps a few years ago. Transformers are very inefficient at low frequencies, which is why, together with lack of mains hum, solid state amps gained supremacy. In the early days it was pop-groups and guitar freaks who clung onto valves as they liked the "soft" way that they overloaded and the resulting distortion. It wasn't hi-fi.

Intermediate stage coupling capacitors are also a limiting factor, so if you get an amp going down to DC, you'll know that you've got the maximum low end available.

Put sufficient power (even 100 watts goes a long way) through the largest possible units and you'll shift some air.

But one has to be careful in choosing units: look at their efficiency. Car boom-box systems boast abilities to sink kilowatts, trading efficiency for apparent ability to sink power for no other reason apparently than to boast high power handling specs to kids expecting to pass GCSE multiple choice paper physics in a series of grades spelling FUDGE rather than old fashioned C in O Levels. :-) I'm not sure that in these days of units designed to shift air in nightclubs, the 18 inch bass unit market is entirely different.

Old H&H units are worth keeping eyes open for - H&H equipment was designed well and engineered for real use rather than merely to boast specs. I have a couple of Fane Colossus 18 units rated at 400 watts which are significantly less efficient (probably around 6dB) than old Goodmans units which work well on 50 watts. Whether they'd deliver better goods on 400 watts, I haven't tried, but if you've got the amp to try them, you'd be welcome.

In the hi-fi world one sees so many stats and specs that really don't mean a lot in practice, sometimes other than a price tag, I tend to follow a pragmatic approach - try it and if it works, use it! You can often find big units available cheaply on eBay so you don't necessarily need to spend a lot of money.

Best wishes

David P
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Re: Reproducing 32' bottom C

Postby organtechnology » Thu Sep 16, 2010 11:51 pm

Well, I now know what a 16 Hz note sounds/feel like.

While attending a Pipedreams program at the Morton H. Myerson center in Dallas, TX , where the C.M. Fisk Opus 100 organ has not one but three 32 foot pedal ranks, there was a demonstration explaining the organ and the lowest C in the pedal was played with only the 32 foot pipe stops pulled. It was impressive but not very musical. Michael Barone called it the 'helicopter pipe' and indeed it did sound like a helicopter was landing.

I think I can do without that in my house.

Pax,

Thomas
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Re: Reproducing 32' bottom C

Postby David Pinnegar » Sat Sep 18, 2010 1:52 am

organtechnology wrote:Well, I now know what a 16 Hz note sounds/feel like.
. . . Michael Barone called it the 'helicopter pipe' and indeed it did sound like a helicopter was landing. . . . I think I can do without that in my house.


Hi!

Actually it depends on the rank - a reed is like a helicopter but a gentle flue can just give a wonderful aura to the music, supporting the harmonics above. It was for fun and love of experiment that I similated a 64ft and 128ft . . . at 4 Hz and, whilst unmusical in itself, it does support above.

if placed in a corner will generally add gain near the low end. Some designs can tolerate some added gain but it really depends on the design. And if it needs that kind of EQ then it's a poor design for the job at hand and the effect is very limited, as the woofer will easily be pushed beyond its Xmax (excursion limits).


Yes - corner positioning is really helpful and is possibly the secret of using simply any old 18 incher or pair and getting a good result.
http://www.youtube.com/watch?v=U4Ie6BHoCw8 shows what I did and
http://www.youtube.com/watch?v=qEVd2vdWYc0 the window rattling that resulted and on
http://www.youtube.com/watch?v=9usBggyS5Nk I'm pretty sure a couple of bottom notes used it.

Meanwhile the multiple choice GCSE brigade take bass power consumption to a new dimension:
http://www.youtube.com/watch?v=IiF_CCbHl_0
http://www.youtube.com/watch?v=w-h_IojGvi4
http://www.youtube.com/watch?v=-IxTrXjSoOE
It's about time an organ got eye popping attention:
http://www.youtube.com/watch?v=N1B-mQlQGFk
- somewhat of a hair raising activity:
http://www.youtube.com/watch?v=D0-yT8IA3W8

The problem with units smaller than 18 inch is that to shift enough air, significant harmonic distortion will result:
http://www.youtube.com/watch?v=xGDofmxwLPY

In posting these videos I hope that a few more people will start to be noisier about showing the younger generation that there is life beyond the nightclub and that thrills extend beyond mere destruction. The organ is the one instrument which has the power to do it, whether powered by wind, mains or Hauptwerk.

Best wishes

David P
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