Is15 inch overkill for music?????experts

[ThorstenL]

Konnichiwa,

I keep hearing about wavelaunch. Anyone wish to enlighten me?

Sound propagates as waves. The term "Wavelaunch" comes from the "launch" of the wavefront by the front (baffle) of the cabinet. As long as the baffle is wide enough a whole wavelength wavefront will propagate without disturbance by the dicontinuity of the baffle ending.

The closer to the point of origin (driver) surface discontinuities occur the less ideal is the resulting wavefront being "launched" at the listener. I personally feel that such discontinuities should either occour at frequencies far above or below the formant range of the human voice and of the main instruments (any crossover should also be kept out of the formant range BTW if possible). The formant range is that which determining for percieved tonality (hence formant from forming) and covers more or less accuratley 200Hz -3KHz...

Sayonara

 

[ThorstenL]

Re: dipole subs

Konnichiwa,

So KYW, it seems you are saying that dipoles are a good way to go for subs.

Not SUBS, woofers. True subwoofers tend to cover the lowest octave (16Hz-32Hz), there omni directional systems (and a single one of these too) are fine.

See also this thread.

http://diyaudio.com/forums/showthread.php?s=&postid=342147#post342147

What do you think about the W and H shaped open baffle dipole subs like these?

Due to their nature they introduce severe cavity resonances, which limit their response at fairly low frequencies. As you need comparably a lot of cone surface in a dipole Sub to got reasonably low you need large drivers and thus large cavities with fairly low cavity resonances. All this rather limits their usefullness.

They seem like a good way to make the cabinets smaller (ie, turning the 15-20" drivers sideways).

You will still need a fairly wide anyway, to accomodate the correct wavelaunch in the formant range of the human voice and classical instruments.

It is time for people to understand a fundamental relationshif for speakers. Namely "Good" in an absolute sense (as in High Fidelity) and "Small" just don't mix.

If you require a small speaker, understand how to manage the raft of problems you introduce by making it small and manage them as well as possible (eg floor to ceiling line sources with a very narrow profile ensuring an even wave proagation throughout the formant range, though NOT corrent wavelaunch).

Otherwise build speaker so they work acoustically and worry about the decor later (or build them smartly to be both large and easy on the eye).

Sayonara

 

[5th element]

I cant open that link you posted it seems I need to be a member of yahoo groups to see it. Oh well.

 

[ThorstenL]

Konnichiwa,

Now this is my idea of a good, great 15" driver.

Hmmm. Compared to really high performance Pro Drivers this is rather pedestrian. The magnet system is mostly showy, but lacks essential distortion reducing features. The Cone may be "high tech" materials, but my experience is the fancy cone materials are more in aid of marketing and production consistency, than absolute performance.

Compared to soem of the cheap and nasty PA 15" Drivers this one is not bad, compared to best high performance 15" it is barely middeling.

Sayonara

Look at the better JBL, TAD, Volt, Precision Devices and Lambda drivers for really good examples.....

JBL 2226 Driver

JBL 2242 Driver

For JBL, observe the qualification for Distortion and power compression and compare to the usual lack thereof (for good reasons, the measured results are often appaling) with HiFi Drivers....

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TAD TL-1601c 15" Low Frequency Loudspeaker

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Volt R3853 Radial Chassis Driver

Precision Devices PD915

 

[ThorstenL]

Konnichiwa,

I cant open that link you posted it seems I need to be a member of yahoo groups to see it. Oh well.

This is a new Yahoo policy, nothing I can do about it. At any extent, the relevant text is fully reproduced at:


http://diyaudio.com/forums/showthread.php?postid=342102#post342102

Sayonara

 

[jewilson]

Kuei Yang Wang,

I find that a 10" or 8" woofer worked best for me. Professional JBL's are "great speakers", however not designed for home speakers. Since they have a short cone excursion, they are limited in their low frequency performance.

Kuei Yang Wang,

So what kind of speaker do you use in your home.
🙂

 

[Sheldon]

Actually IMHO all the way into the lower midrange.

At the moment I am using 2 15" woofers per side in open baffles,
from ca 40 to 270Hz , horns cover the rest.

cheers 😉

And how far away from the walls are they located - esp. rear wall? I'm interested because I'm thinking of going a similar route. I'm going to use Unity horns crossed over about 300 hz to the woofers.

Sheldon

 

[slowmotion]

Hi Sheldon, all

The woofers are in 140cm wide and 120cm high flat baffles.
They are 120cm from the back wall and allmost touching the sidewalls.

cheers

 

[Sheldon]

Thanks Jan. Ever tried them closer to the rear?

KWY, I know that you run your wide rangers somewhat closer to the rear than usual. I can understand the issues in the mids, with reflections reaching the listener too soon to sort out from the direct sound. What are the limitations below about 300 hz? Too close to the wall, do you begin to get more box like performance or resonance between speaker and wall?

Sheldon

 

[slowmotion]

Thanks Jan. Ever tried them closer to the rear?

Sheldon

Well, I would actually have liked them further out in the room ,
but unfortunately doors and windows prevents this.

I also have some bookshelves on the back wall behind the
baffles , I don't know if that have any effect at these frequencies.

cheers

 

[454Casull]

454Casull

I have only head a few speakers that had tight bass that used a 15" woofer that was a JM Audio Lab Utopia. Great for sound reniforcement.

No problem with low frequency diffraction but when you build the rest of the cabinet you will end up with a wide cabinet.

You have to have a room that is long enough to reproduce a 20 Hz wave length or it does not happen.

Most 15" drivers don't sound good till they are playing loud.

6) http://www.contrabass.com/pages/frequency.html that interesting but most of us don't listen to a Tuba.

So what 15" drivers do you like......

Stop saying that you need a room of a certain length to reproduce a certain wavelength! How can you hear low frequencies inside a car, then?

And most symphonies have a tuba player (I'm pretty sure some have more than one).

 

[Variac]

Professional JBL's are "great speakers", however not designed for home speakers. Since they have a short cone excursion, they are limited in their low frequency performance

Here's a well known subwoofer made from a well known JBL 15" pro driver, the 2666 These drivers are not designed for sub use, so require electronic bass boost, but they have enough area and excursion to handle very low notes. Modern pro drivers have more excursion than older ones that you may be thinking of. I guess they deal with the potential distortion increase in other ways....

http://member.newsguy.com/~stigerik/almighty/

A 15 inch woofer is not suitable for producing >400Hz. (in fact 250 Hz is a better choice)
Mostly higher x-over freq is choosen because passif components become costly at lower freq, or active x-over thus bi-amping is needed (and of course 3 or 4 speakers instead of 2 or 3).

Stretching the abilities of a speaker in extending frequency-range is proppelled by economic reasons, not because of sound quality.)

Keep in mind that the cone of a 15" driver- or most other woofers generally doesn't act like a piston. Different parts of it (close to the voice coil) decouple and vibrate at higher frequencies. So the decoupled part is a lot smaller and lighter than the entire cone. The old Altec Lansings are reputed to be able to cover over 1000hz due to this very carefully controlled breakup. People who like this sound point out that there is a gain in sound quality due to not requiring a crossover-that the sound is more consistant and cohererent. They are not preferring it for economic reasons.

I have no experience with the Altecs, but I have heard PROPERLY used, wide range drivers like Fostex that sound really good. You have to deal with the response peak though- or they sound like good transistor radios

Kuei:
re wave launch: so the cabinet width needs to be the same as the wavelength that you are trying to launch?

 

[ThorstenL]

Konnichiwa,

I find that a 10" or 8" woofer worked best for me.

Fine, i usally find such systems a little too challenged to not turn to amorphous mush when the orchestra hits FFFF.

Professional JBL's are "great speakers", however not designed for home speakers.

Funny, JBL is using exactly in such application, look at thei K2 Speaker series and more to the point, go and listen to them....

Since they have a short cone excursion, they are limited in their low frequency performance.

The 2226 I mentioned has +/- 7.5mm linear and +/-20mm damage excursion. Compare this to to the top of the range Scan Speak 10" Woofer which has +/- 9mm linear excursion and +/-14mm damage. You find that the numbers are a little better for the "HiFi" woofer, on pure linear excursion, but not by much - and note - we are looking at one of the best available 10" HiFi Drivers.

HOWEVER, the 15" JBL has about three times the cone surface, so if it is asked to reproduce a given note at a given SPL it will be required to move only 1/3rd as far as the Scan Speak 10" Woofer. The result, lower distortion and interestingly, more "speed".

Comparing the "Motor Strength" for both drivers to the moving mass shows actually about level pegging, as the Scan Speak driver has an exceptionally high Force Factor for a HiFi Driver.

More interesting would be the distortion Levels BTW, which for the 2226 are measured and specified, while they are lacking for the Scan Speak, plus also the power compression levels....

So, I may submit that all else not being anm issue (eg size, cost) the 15" JBL will provide not just better absolute fidelity, but from my experience also a subjectively more realistic sound.

Kuei Yang Wang,

So what kind of speaker do you use in your home.
🙂

A pair of 8" Fullrange Drivers on open baffles with a Dual 12" Subwoofer, this strictly in the interest of domestic harmony and bliss, with aknowledged limits in terms of maximum levels without starting to sound congested. See here:

Prior to that anything between 8" Lowther Equipped Horns, 10/12" Fullrangers and 15" Tannoys at home, plus rafters of other stuff heard all over.

Sayonara

 

[jewilson]

Yang Wang

So where are the speakers. all I just saw this babe in your picture.

It funny you say systems with 8 and 10 inch wooffer challenged. I find systems with the 15" drivers bloated, if their not in a large room.

I don't know any one that using JBL in a home system. Back in the 70's I owned several pair of JBL speakers sudio monitors. These had 15" drivers but I can get deeper bass out of a pair of 10" Focal. I am sure they have improved them buy now.Of course they would play dam loud.

You might want to check these JBL out.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3709121307&category=23794

 

[ThorstenL]

Konnichiwa,

So where are the speakers. all I just saw this babe in your picture.

The speakers are the silver box to the right (subwoofer) and the Acryliuc Baffle and driver to the left. The "Babe" is my wife... ;-)

It funny you say systems with 8 and 10 inch wooffer challenged. I find systems with the 15" drivers bloated, if their not in a large room.

Low frequency bloat is a direct result of incvorrect LF tuning. In speaker design you need to account for room gain and room modes (see the new thread I started on this).

I don't know any one that using JBL in a home system.

Pitty. But i noticed that in the US JBL stopped sales of their large format "domestic monitors" ages ago, as did tannoy. In Europe and Japan (where rooms are small) sales are still strong.

You might want to check these JBL out.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3709121307&category=23794

They are okay, but for my tastes in the context of an uncompromised High End speaker System woofer a little on the small side and too large as wideband midrange. Try 21" or 24" Drivers in a dipole woofer and a 12" or 15" Coax as "wideband midrange", covering around 30Hz Upwards with another 21" or bigger in a sealed box for really low sub bass.

Sayonara

 

[RHosch]

The smaller the room, the easier it is to produce low frequencies, as the in-room measured response (of a perfectly sealed and rigid room) increases 12/oct (going down) below the first eigenmode. It's easier to produce 20Hz at 100db in a car than in a small room. It's easier in a small room than in an auditorium. Both of these assume the same driver to microphone distance.

 

[Hybrid fourdoor]

Re: Re: To 15" or not to 15" that is the question

You obviously fail to draw up the whole relationship. A freind of mine once had a full racing trim Camaro, including around 5 Liter Engine and reall good breaks. It also was a fairly heavy car, compared to most compact european cars. So, it was a heavier car, hence by your logic it was a worse car, especially it would seem when it comes to acceleration, breaking and top speed. So clearly a 40 Horsepower Volxwagen Polo is faster and acelerates better, because it is lighter? You may wish to test that theory at any local traffic light....

Unless you relate the mass (Mms) to the ability to accelerate and decelerate this mass (B/L factor) you will draw inaccurate conclusions. The cone mass on it's own is completely irrelevant, just as the mass of a car is completely irrelevant on it's own, as measure to quantify ANY element of performance.

I think the point that is trying to be made is that many larger speakers also have larger motors. So even though the cone is larger, a 15" driver (especially PA drivers) might have a 4" voice coil and and an over sized magnet. So yes the cone is heavier, but it has a much larger magnetic feild and better leverage. It still has a similar ratio.

Also this can easily be compared to engines, just not in the way you like. As said above yes a heavier car with a better weight to horsepower ratio will be faster (in the straights at least, and lets admit it Bass is the audio equivelant of drag racing). However the size is only a part of the equiation. Geometry is much more important. For example the Honda S2000 motor is 2.0L and is capable of 10,000 RPM's as a production motor and the 5.7L Corvette LS1 is more comfortable under 6K, however some motorcycle engines are capable of 15K+ RPM's and CART's 3.?L engines go up to ~13K RPM's (with about 1800 miles life expentency 🙁 ) , and my first car a 1986 F250 with a 460 (7.?L) in it never saw above 3500 RPM. The only thing that makes these engine able to vary so much is geometry. Some have bigger bores than strokes and can go really high for more horsepower at the expense of torque, while others have bigger strokes than bores and have a ton of torque down low (read easily driveable), but lack the mechanical stability to have high RPM's.

So the point is that if a 15" is setup properly, more surface area and less travel, it will (in my opion) perform as good if not more effertlessly than smaller drivers.


Course theres always the Rotary, this is the eletrostatics of engines. 7 moving parts and can easily go to 10K+ RPM's with just some port work. There are 2.0L 3-Rotor cars out there putting out 500HP to the wheels using stock everything and very reliable.

 

[Sheldon]

So the ideal speaker design would be a 4 driver pentroof? Or should we go with 5? 😎

Sheldon

 

[richwalters]

Moderator........perhaps some ought to segregate mail into true Hi Fi, car audio and PA into sep forums.........I don't think we need to blend in < performance car engines> in the 15" forum ? There ain't no match with combustion.

rich

 

[454Casull]

Re: Re: Re: To 15" or not to 15" that is the question

I think the point that is trying to be made is that many larger speakers also have larger motors. So even though the cone is larger, a 15" driver (especially PA drivers) might have a 4" voice coil and and an over sized magnet. So yes the cone is heavier, but it has a much larger magnetic feild and better leverage. It still has a similar ratio.

Also this can easily be compared to engines, just not in the way you like. As said above yes a heavier car with a better weight to horsepower ratio will be faster (in the straights at least, and lets admit it Bass is the audio equivelant of drag racing). However the size is only a part of the equiation. Geometry is much more important. For example the Honda S2000 motor is 2.0L and is capable of 10,000 RPM's as a production motor and the 5.7L Corvette LS1 is more comfortable under 6K, however some motorcycle engines are capable of 15K+ RPM's and CART's 3.?L engines go up to ~13K RPM's (with about 1800 miles life expentency 🙁 ) , and my first car a 1986 F250 with a 460 (7.?L) in it never saw above 3500 RPM. The only thing that makes these engine able to vary so much is geometry. Some have bigger bores than strokes and can go really high for more horsepower at the expense of torque, while others have bigger strokes than bores and have a ton of torque down low (read easily driveable), but lack the mechanical stability to have high RPM's.

So the point is that if a 15" is setup properly, more surface area and less travel, it will (in my opion) perform as good if not more effertlessly than smaller drivers.


Course theres always the Rotary, this is the eletrostatics of engines. 7 moving parts and can easily go to 10K+ RPM's with just some port work. There are 2.0L 3-Rotor cars out there putting out 500HP to the wheels using stock everything and very reliable.

Your analogy between the Wankel and electrostatic speakers is flawed. Rotaries are VERY inefficient due to the long combustion chamber, which means much of the heat is lost to the cooling system.

Besides, high RPM doesn't necessitate low torque. If the intake/exhaust systems are designed well, the torque of a high bore/low stroke cylinder will almost stay the same (assuming the displacement is the same as a cylinder with square ratio or something), because the decrease in crank distance is offset by the higher force on the piston (F = PA) - area increases, while d decreases, but the displacement - and thus, the pressure - stays the same.

Sorry for the blathering, I just woke up. 🙂