Subwoofers in the midrange...

Original in Audio Asylum

 

Too many generalisations and inaccuracies there Antonio to go into whilst I am at work, but I would agree about firing the cone into the floor being a disadvantage.

But you might want to go and look at the JBL pro audio site and check out the frequency responses of units like the 2235 and others before posting someone's erroneous theories

 

I'll save Antonio the trouble of looking it up:-

http://www.jblpro.com/pages/components/2235h.htm

P.S. I'd like to add that a certain Tannoy DC driver also does very well in this dept (18Hz-22KHz)

 

I agree with Merlin that there are too many generalisations here.

For example, the frequency at which the bass becomes directional varies with the size of room. A frequency at which bass is directional in a large room may not be directional in a smaller room.

As regards position, again there are no definites here. In some rooms I have achieved the best results with one or two subs located in a single corner of the room, where all room modes were more fully engaged. My subs cross over at 125Hz but I haven't generally had problems with sound location (perhaps because the subs fire into the floor) or integration.

Talking of which, I cannot agree that floor-firing subs are, in themselves, inferior. It depends on the frequencies involved and also, believe it or not, the height of the room (owing to floor-ceiling resonances). Floor firing will also act as a useful (and adjustable) additional low-pass filter, and can have other advantages as well. Changing the height of the spikes (or superballs ) can control the integration with the main speakers.

I'm glad that the post said that you'd need about three 8" or two 10" drivers to achieve good bass response. Other than the fact that placement of the sub will have an enormous effect on the SPL (output in the corner is several times output in a room anti-node), much will depend on the particular driver. For example, an 8" driver with a maximum cone excursion of 1" is a very different animal to one with a maximum excursion of 1/2". Much also depends on the design of the enclosure. For example, a well designed transmission line enclosure can achieve greater deep bass response from a single driver.

Of course, there's also a massive difference in treble response between drivers with light or heavier cones but I won't go into that right now.

Suffice it to say it's very difficult to generalise in this area (unless your name is Richard Bassnut Greene - a gentleman who's very knowledgeable but not always right).

 

Too many generalizations, what does that mean...

Every rule is a generalization, with all the exceptions to confirm it, without generalizations you get nowhere, IMHO, you dont want everyone in every situation to try and test everything, one has to start with general rules, except for audiophiles, who are different from everybody else, so general rules dont apply...

If you remove your wisard hat for a second, you will agree that his rules are common sense, unlike your "personal" lack of rules... :MILD:

 

OK Antonio,

firstly, just about everything he says is in reference to the use of one single subwoofer, and I would tend to agree but argue that a mono bass source is an unacceptable compromise.

Secondly, saying that no speaker needs crossing over above 100hz, does not mean to say that they cannot benefit from it. Take a look at the Nesterovic's used by Titian, also look at most two and a half way designs sold by household names such as B&W.

Adding weight to the midbass and lower midrange allows a sense of grandeur to appear that creates an effortless and large scale presentation. It is not all about extension, indeed designs such as the subs created by Living Voice offered very little gain in extension compared with the standalone Airscout. What they offered was that sense of scale and effortlessness.

As for his comments regarding large drive units, this may hold water when discussing drivers designed to reproduce sub 20hz signals at high levels, due to the weight and stiffness required to avoid excessive distortion. Many 15" drivers are however designed to be flat to 30hz or so, ad these will happily cover 5 octaves in a domestic or professional setting, offering at the same time extraordinary dynamics and power. Again, look to JBL, ATC, TAD, and many other manufacturers for confirmation.

Now in adopting the high crossover approach there are pitfalls, and I certainly would not advise doing it without some knowledge. But it is not breaking any rules - merely enhancing the performance of a system through careful selection of components and creative setup.

Obvious potential hazards are off axis lobing, phase irregularities, and time domain issues. Once you understand this, it is reasonably easy to work your way around these pitfalls.

 

To xover higher than 80hz, or 60hz wich I prefer, you need a xover designed for that combination speaker/subwoofer, because of the problems you mention, "off axis lobing, phase irregularities, and time domain issues", with of the shelf xover or bass management it just doesnt work properly...

 

Whatever you say Antonio

I guess Bryston and others should stop making those active crossovers then, seeing as they are non driver specific. Downright scandalous

As I tried to point out, the issues you refer to are relatively easy to overcome with a little common sense, but the theorists will tell you that these detrimental effects will screw the imaging etc.

Not my experience, and of course, that is something I have which sadly it appears you do not as yet

 

Haing recently heard merlins system I can confirm that having the subs crossed over at 200 hz really doesnt affect the sound negatively in any way. In fact it is wholly positive. The system has an utterly effortless sound quality with stunning bass and some of the best imaging I have ever heard.

 

I can't think of any reason on Earth why it should, as two subs are used.

If the subs were positioned below the main speakers, they would be called 'big speakers'. They'd have a bass crossover at 200Hz and no one would even discuss the issue. The wavelength of the sound waves at 200Hz is about 5 feet 5 inches (or 1 metre 65cm). That means that removing the subs from the 'big speakers' and placing them nearby won't make any difference.

I designed my speakers on precisely this principle and, whereas I don't like to constantly harp on about them, there's such a load of rubbish put about and discussed about bass and subs, it drives me crazy. :crazy: :crazy: :cry: :banghead:

 

Sure, keep blabbing, thats why speaker xovers are just a CAP and a coil, the ones with extra components to compensate for ressonance peaks, etc, are downright scandalous...

As usual you know all and have the only perfect system in the world, if only for a month...

 

Describe imaging...

 

You are right...

 

Antonio,

anyone would think you had rediscovered vinyl given that your posts are starting to sound like a stuck record

If you don't have a coherent arguement, and in the light of other people's posts, why don't you just accept that those of us with some experience in this matter just might be right?

FWIW I wouldn't recommend higher crossover points for many domestic subwoofers from the likes of Rel and others - the drive units are simply not of a high enough quality and the amps are not really good enough for PA work

 

I learned to repeat myself with you great wisard...

I am the most experient, I am the most experient, I am the most experient...

My arguements are coherent, they dont change with the flavour of the month, like yours...

 

Antonio, err soudstage, and ability to locate instruments within the soundstage

One thing is for sure, the subs sound way better than any poxy REL subs I have heard.

 

Does anyone have a large cellar under their listening room?

Does anyone have a large cellar under their listening room? I've got a design project that I need some help with.

I'd like to build a pair of large subwoofers to cover the 15Hz to 30 Hz octave only. I figure to move some serious air and plan on cones with diameters of about 10 feet, driven by massive electromagnets. I don't think the mass is too critical at these frequencies and plan on using human ballast.

I propose to attach merlin to one sub and lowrider to the other. The only other thing I'd need is some absorption material to eliminate the medium frequency thud that we'd get whenever their heads banged together.

Can anyone help?

 

Ga Ga Ga There you go - is it feeding time yet

 

Nice constructive posts as usual, what is next after calling me an animal and the racist comments...

 

Antonio,

you will find the attempts at constructive posts at the beginning of this thread.

As you have chosen to ignore them, and act like a child, you must expect to be treated like one

If you would prefer to have an intelligent debate, then please do present a cohesive argument.