Pass EL PIPE-O with BD15? (Drive Units)

by Giovanni, Ravenna, Tuesday, March 13, 2007, 18:42 (3962 days ago)

Another bad thought today.

[image]

Very easy to build with PVC or sonotubes, with one or two drives each. Just cut the tube half the desired wavelenght. Here the article:

http://www.passdiy.com/projects/el-pipe-o-1.htm

nnelson Pass coupled these with his "Klein horns"

[image]

Would the BD15-El Pipe match the Oris?

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Pass EL PIPE-O with BD15?

by Bert @, Tuesday, March 13, 2007, 19:30 (3962 days ago) @ Giovanni

Hi Giovanni,

Would the BD15-El Pipe match the Oris?

It would need more EQ I think and the sensitivity will never match the Oris. In both situation you have to go active or reduce the sensitivity of the Oris horn. You can use them in such a configuration without a problem though.

One note, just taking the quarter wave to go as low as desired is one but even better would be to calculate the length for a frequency in between room modes (also standing waves as generated by the pipes) trying to balance the room response...

Ciao,

Bert

--
BD-Design - Only the Best!

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Pass EL PIPE-O with BD15?

by GC, Tuesday, March 13, 2007, 19:40 (3962 days ago) @ Giovanni
edited by GC, Tuesday, March 13, 2007, 20:36

Another bad thought today.

Hi Giovanni

If you ask me, and I don't know if you do?, then a TL is not the very best choise of principle for neither the BD15s or if speed should be a feature.

A TL is an opposite of horns (and should optimally show a curved narrowing (flare-rate) similar to horns) ending with a final port of "tuning". It means the TL show a higher and higher acoustical impedance towards the lows leading to in-efficiency, need of amp power and finally long P-P travel lentghs for the drivers diaphragme and special designed VC over hanged mag. systems and installed weak magnetic force. (You can popularely say the "damping factor" is a result of the TL and not the driver it self (Big mag. force))

True is that some TL's shows some rather fine apperiodical qualities and can sound pretty dry. But they all lack "freedom", speed and articulation.

If the TL should show a wide band-pass it would not be efficient at all. If it should show efficiency it should be tuned to a very narrow bandpass and will then just show a steep peak at the tuning freq.

I think it is a general mistake to try to introduce very low frequencies into normal sized listening rooms. Don't forget how long a full wave of a 20Hz tone is. 16.5 meters. So...as we know it's best that a full wave can be enclosed in the room/box, if chaos should not be the result, then we better forget it.
What happens if we try to linearlise our speakers flat to 20 Hz the room amplification in this region may leave us with peaks and dips of 10-20 db's!!!
Only thing to do here then, is to open doors and windows the let the energy out. :shame:

CaNot be that interesting to aim at. :no:

IMO if you go ORIS, stay with the BD15's as per lay-out of DB-designs. Much research and know-how are reflected in those options.
Any of BD bass system will be superior to a TL, :wink: and may be tweaked to reach pretty low given the attention to the max P-P displacement and acceptable distortion.

:rolleyes: GC

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Pass EL PIPE-O with BD15?

by Giovanni, Ravenna, Wednesday, March 14, 2007, 01:02 (3962 days ago) @ GC

Hi GC,

congratulations for your Swings and listening room :cool:

For the time being I like to experiment and enjoy the art of compromise. In my small listening room there is not enough space for Oris reference bass enclosure, and even the Compact model wouldn't be angled correctly.

TL pipe idea is good because it goes to a corner close to the wall in 40x40 cm space. I don't need it to go so low, 40 hz are enough for classic music, the important is that a doublebass must sound louder than a cello playing the same note.

I agree that horns are better than TL, but if you have no room for a mouth large 1/4 wavelenght Fc and a horn 1/2 wavelenght long, that is a compromised horn. Maybe a less compromised TL sounds better.

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Pass EL PIPE-O with BD15?

by GC, Wednesday, March 14, 2007, 06:10 (3962 days ago) @ Giovanni
edited by GC, Wednesday, March 14, 2007, 06:17

Hi GC,

congratulations for your Swings and listening room :cool:

Thank you very much Giovanni :cool:

For the time being I like to experiment and enjoy the art of compromise.

It is an art indeed to hit the best compromise.

In my small listening room there is not enough space for Oris reference
bass enclosure, and even the Compact model wouldn't be angled correctly.

Yaeh...that set's at least some trade-off. Were thinking of your room could be small then? Then I would be reluctant to go lower than you aim at 40 Hz...and further limit eventual insane listening levels.

TL pipe idea is good because it goes to a corner close to the wall in
40x40 cm space. I don't need it to go so low, 40 hz are enough for classic
music, the important is that a doublebass must sound louder than a cello
playing the same note.

Yes Giovanni. It is not easy either in this case than to compromise.

I agree that horns are better than TL, but if you have no room for a mouth
large 1/4 wavelenght Fc and a horn 1/2 wavelenght long, that is a
compromised horn. Maybe a less compromised TL sounds better.

It is certainly not nessecerely so that horns are better than TL's and BR better than closed boxes etc. All principles may be tuned to their best...but they sound very different.
There are so many parameters to taken into account when all things are put together.

GC :yes:

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Some second thoughts...

by Bert @, Tuesday, March 13, 2007, 19:52 (3962 days ago) @ Giovanni

Thinking about it a bit further, in the past I did build something similar (much smaller though) but then with the pipe length tuned to the resonance frequency of the enclosed volume wherein the bass driver is mounted. A factor 0.7 lower.

This works like a sort of reflex enclosure but then going deeper more effectively and more even in frequency. Nice principle for 6 or even 8" woofers to keep the size a bit down. More effective (after damping it for flat response) as the tube as shown in the article.

The tuned pipe didn't need much damping material...

I would go for your Singular idea though.

Ciao,

Bert

--
BD-Design - Only the Best!

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Some second thoughts...

by GC, Tuesday, March 13, 2007, 20:26 (3962 days ago) @ Bert
edited by GC, Tuesday, March 13, 2007, 20:53

Bert

Suddently I also started to reflect over my very past designs and ways to overcome most common problems with sound control.

In my beleives that it is wrong to try to prisson or capture sound in a boxed design...be it a cabinet or the listening room... I once made a 3 way speaker where i took a flex-pipe and ventilated captured preassure of each chamber in the cabinet out of the listening room and into the free open air.

I did it for all 3 involved drivers (treble drivers too..yes)

Hello! :idea: I dialed a good number with this experiment.

But the trade off were of course the redicilous lookings of such a monster.

Hmmmmm :confused:

I remember the summers I took my speakers into the open garden, placed them on a podium 1 meter high, drew a 50 meters long speaker cable and got them going.

Wow, then I knew what a listening room is doing to the sound.....:scared: Kept this in mind with my future philosophies about cabinets.

The SWING's internal construction and it's vent technology is inspired by those learnings. (As you know).


GC

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Some second thoughts...

by Giovanni, Ravenna, Wednesday, March 14, 2007, 00:21 (3962 days ago) @ Bert

Yes, the pipe must be tuned to half resonant freq of the driver: the other half is done by the free space in the ceiling where waves reinforces without obstacles.

In my small dedicated listening room I've space for 35-40hz half waves, so I thought to a driver with Fs in that range with a pipe 240cm long.

Maybe BD15 is overrated, as it needs a 40cm width pipe minimum, and goes lower than I need, but it has the best spec.

The Pipe would have its own powerful amp and its own DAC. I have two DACs sourced by PC with common master clock, so all EQ would be done (live) in the digital domain.

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Some second thoughts...

by GC, Wednesday, March 14, 2007, 05:57 (3962 days ago) @ Giovanni
edited by GC, Wednesday, March 14, 2007, 06:16

Yes, the pipe must be tuned to half resonant freq of the driver: the other
half is done by the free space in the ceiling where waves reinforces
without obstacles.

In my small dedicated listening room I've space for 35-40hz half waves, so
I thought to a driver with Fs in that range with a pipe 240cm long.

Maybe BD15 is overrated, as it needs a 40cm width pipe minimum, and goes
lower than I need, but it has the best spec.

The Pipe would have its own powerful amp and its own DAC. I have two DACs
sourced by PC with common master clock, so all EQ would be done (live) in
the digital domain.

Hi Giovanni

I'm not sure we were talking about the same thing here?

I were pointing at the "de-preassure" blessings, not the TL as such. :wink:

Maybe BD15 is overrated, as it needs a 40cm width pipe minimum, and goes
lower than I need, but it has the best spec.

But I don't think at all the BD15's is designed to meet TL criterias. It will play of course, but you will likely need some EQ regardsless the TL. The BD15 has a big magnet-to-moving mass ratio and does not look excactly as a TL dream driver to me.

But who said the bumble-bee couldn't fly? :pardon:


GC

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Some second thoughts...

by Giovanni, Ravenna, Wednesday, March 14, 2007, 12:35 (3962 days ago) @ GC

I'm still learning about drivers coupling in bass speakers with TL, vented or sealed enclosures.

I only need "natural" thick sound in the range of 40hz-200hz. I know how ridicolous is a cello note at 30hz in exaggerated bum bum systems (it doesn't exist, as a live cello can't go lower than 50-60hz).

Still learning best Thiele Small parameters for TL bass enclosures. It is funny, looking at drivers spec, these are different, in different suppliers web sites, for the same model! :shame:

Have you any experience for a 10" or 12" driver suitable for a TL?

I can tell you what is the absolutely best commercial Tripath based amplifier :wink:

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Some second thoughts...

by GC, Wednesday, March 14, 2007, 13:30 (3962 days ago) @ Giovanni
edited by GC, Wednesday, March 14, 2007, 13:36

Giovanni

Have you any experience for a 10" or 12" driver suitable for a TL?

This guy will help you out. He can do any customized design you may want (almost):

http://www.audiotechnology.dk/iz.asp?id=4|a|132|||

The TS parameters for TL is normally a low Fr -> high Mms, relatively high Qts -> 0,5, and relatively small magnet force -> 1T or so.

GC

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Some second thoughts...

by Giovanni, Ravenna, Wednesday, March 14, 2007, 14:01 (3962 days ago) @ GC

Thanks for link and specs. I started studying.

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Please stay on topic...

by Bert @, Wednesday, March 14, 2007, 14:15 (3962 days ago) @ Giovanni

Giovanni,
:attention:
Please stay on topic!

If you want to talk about another issue then do start a new topic. I have deleted the parts which were not on topic... :rules:

Moderating rules... :cool:

Bert

--
BD-Design - Only the Best!

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just do it

by fu_man @, Wednesday, March 14, 2007, 14:01 (3962 days ago) @ GC

Giovanni...

build them - you know you want to! I've seen these before on the NP website and thought they look like a lot of fun to build. Part of their attraction is their extreme nature. If you built them you would not regret it, even if they don't sound as you hope for you will learn a lot, have a lot of fun, have fond memories of that crazy thing you did once (like GC and his flexi-pipe vents!) - and so long as you don't do what Nelson did and blow up the drivers, you can always reuse the drivers - especially if you do use BD15's because you know that there is a design for these that will work well.
If you don't build them, you will always wonder... and you will waste time trying to convince other people on web forums to just do it.:wink:

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An even better idea..

by Bert @, Thursday, March 15, 2007, 15:18 (3961 days ago) @ Giovanni

Thanks to Leif...

[image]

Only for sub below 40Hz though...

--
BD-Design - Only the Best!

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An even better idea..

by Giovanni, Ravenna, Thursday, March 15, 2007, 16:03 (3960 days ago) @ Bert

Hi Bert

Thanks. Take a look at BIB concept

http://www.zillaspeak.com/bib-howtobuild.asp

The concept is to get half lowest wavelenght desired (usual driver Fs). Maybe it applies too to the design you posted (building it 2,4m tall for half 40hz wavelenght). It can be a choice if I don't like the FW208 in the singulars :grin:

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An even better idea..

by Bert @, Thursday, March 15, 2007, 16:20 (3960 days ago) @ Giovanni

Hi Giovanni,

The concept is to get half lowest wavelenght desired (usual driver
Fs). Maybe it applies too to the design you posted (building it 2,4m tall
for half 40hz wavelenght). It can be a choice if I don't like the FW208 in
the singulars :grin:

You will like the Singulars with the 208's, much more wide band and more even in response than the TQWT you show through the link.

Ciao,

Bert

--
BD-Design - Only the Best!

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