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Author Topic: Gona try this another way  (Read 2258 times)

Luke Geis

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Re: Gona try this another way
« Reply #30 on: May 15, 2018, 11:22:17 pm »

Typically you need to delay the mains to the subs regardless of being horn loaded or direct radiating. The crossover type usually has a phase shift of between 90* to as great as 720* depending on filter type used. 360* phase shift isn't as bad, since it puts the subs one full cycle behind the mains. With a 12db per octave filter and the subsequent 180* phase shift, most will just run the subs in reverse polarity. This can often address that issue and in both cases, you are in phase, but 1/2 or 1 whole cycle behind in time. Not ideal.

Now that phase shift assumes that the mains and subs are in essentially the same space and plane. Most people ground stack PA systems, so this phase shift will be more evident. When the Main Pa is " in the sky " and the subs on the ground, the distance between them can often change that relation even more. Sometimes for the better, and sometimes nowhere even close. Now I won't argue whether it is correct to align the mains to the subs or not, because that pretty much answers itself......

Our predominate job is to do no harm. In essence we should strive as much as possible to reproduce sound that is as accurate and true as it can be. This means not short cutting certain aspects of what we do. Budget is usually our largest enemy, followed by client / event coordinators and venue logistics keeping us from setting up as we would wish to. The physics can't be changed or argued, so anything that goes against the physics is working against us. Ideally we want to design a system that allows the physics to work in our favor, greatly improving system performance. Cheap speakers don't help.

Horn loaded subs are great at certain things that direct radiating subs can't even compete with. However there are certain things that direct radiating subs excel at as well. Which type to use is part of the system design process. Neither is a perfect tool. In your case you want to build an inexpensive sub, with an inexpensive speaker.  More power to you, but don't tell us that you intend to make an inferior product, that you also intend to neglect even the most basic system setup procedures as well.

The most popular EDM, dub and rave systems typically utilize Function 1 and the like, which are predominately horn loaded systems. As to how good a PA sounds vs how loud it gets is a subjective debate. Lets just say that a million dollar PA can play just as quiet as a $1,000 system. Low headroom systems ( inexpensive ) often don't sound good and even more often don't sound good when loud. You can EQ to your hearts content, but that is only masking the underlying issue. Furthermore, heavy use of EQ reduces peak SPL potential while also causing other phase related issues. A system is only as good as its weakest part.
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Matthias McCready

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Re: Gona try this another way
« Reply #31 on: May 16, 2018, 09:08:38 am »

Not sure if I agree, the VBSS is a $90 dayton PA driver, its not a home audio driver. Sure home audio people may be using it, but the driver itself is designed for PA use, so is the inuke 3000 and the dsp in it.

So what part makes it a home audio sub then? I mean I've seen tons of vented front loaded subs with two circle ports before, hell I owned come create ones years ago that had 4 circle ports, one in each corner, I don't think its the circle port that makes it home audio cuz its commonly used in PA.

Yes, it is using a "PA Driver" however the type of driver does not itself define the function of the speaker, the design of the box does as well in addition to other factors. This is more than looks (ports, basic layout etc). You could try using one of these if you wish, but I do not believe it (or a wall of them) would be loud enough for your intended usage. In a living room, I am sure that is a great sub, but its intended purpose is different than your needs. If you are on a budget this would not be a good approach.


So if its not the driver, its not the port and its not the shape... This is a home audio sub cuz people are using it for home audio?

So if I buy a pair of JBL PA dual 18s and use them for home audio, they are home audio subs now?


No and no, using something at home does not make it consumer audio, just as using something in a larger capacity does not make it pro audio.

Yes, they can look similar, and there is even some driver crossover between the markets. However, it is the intended usage that defines the type of speaker, again not the driver itself. If you want to try using home audio products for this, by all means, try, in the end, you would find you would have low output and a plethora of blown drivers.

For example, it is fairly inexpensive to get a home listening system that is reasonably flat and accurate, however, PA is designed with one primary purpose, to be loud and to do what your home speaker cannot. It takes a lot of money to get the power of PA rig and to get close to how good a home system can sound.

You can, of course, put PA speakers in a home, it does not magically change their function. They still usually have a hiss from the amplification (very noticeable in a small space) and will be intended for volume and not fidelity or clarity.

...none of this is the reality, so I'm working within my limitations of price, genny power limits and current amps I already own.

If resources are limited, this is all the more reason the process of designing and building subs should be done intentionally, based solely on what your needs are, coverage and SPL. If establish your goals and you use designs which are intended to meet them, you will get good results and should be able to keep using your amps and generators.

It certainly sounds like you can build this stuff. In the end building speakers can be very enjoyable and rewarding experience, however, some homework on the front will save a lot of headache and extraneous cost. I am not advocating that you do not build by any means, only that you consider your intended goals and that you have a healthy respect for the art and science of cab construction.

Also, a well-designed sub, properly processed and deployed will play notes accurately, if this is not occurring look back at the previous steps.

Art Welter, a skilled speaker designer and builder, and Luke Geis are giving you some solid advice.
« Last Edit: May 16, 2018, 01:20:37 pm by Matthias McCready »
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David Winners

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Re: Gona try this another way
« Reply #32 on: May 16, 2018, 12:21:53 pm »

Mr. Welter,

How would that little driver fair in a Keystone?

I'm currently having 4 Keystone cabinets built for me by a cabinet shop. Can't wait to get them loaded up and rocking.
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Art Welter

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Re: Gona try this another way
« Reply #33 on: May 16, 2018, 02:53:14 pm »

Mr. Welter,

How would that little driver fair in a Keystone?

I'm currently having 4 Keystone cabinets built for me by a cabinet shop. Can't wait to get them loaded up and rocking.
David,

The Rockville RVP18W8 has a fairly weak motor (18.7 Bl) for horn use, and the 5mm Xmax is anemic. Its output potential would be at least 10dB less in the low end than a B&C18SW115-4 in the Keystone.
At 35 Hz, it might take all four RVP18W8 loaded cabinets to equal one
loaded with a B&C18SW115-4.

That said, it would fill the empty holes, and be around 6 dB louder than it would be in a bass reflex, and have about an octave more bandwidth than the band-pass design the OP is "playing" with.

Cheers,
Art

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David Winners

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Re: Gona try this another way
« Reply #34 on: May 16, 2018, 07:18:45 pm »

David,

The Rockville RVP18W8 has a fairly weak motor (18.7 Bl) for horn use, and the 5mm Xmax is anemic. Its output potential would be at least 10dB less in the low end than a B&C18SW115-4 in the Keystone.
At 35 Hz, it might take all four RVP18W8 loaded cabinets to equal one
loaded with a B&C18SW115-4.

That said, it would fill the empty holes, and be around 6 dB louder than it would be in a bass reflex, and have about an octave more bandwidth than the band-pass design the OP is "playing" with.

Cheers,
Art

That's about what I was thinking.

I'd rather spend money on drivers than plywood, haul and store fewer subs, and have my subs loafing along instead of running on the ragged edge.

The BC18TBW100-4 is $343 from Parts Express. Unless birch plywood is free, it would be cheaper to build 4 Keystones and buy 2 NU6000dsp than to build a pile (16) of cabinets with $60 drivers.

Add a couple barn doors and you would be all set for EDM at 40'.
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Geert Friedhof

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Re: Gona try this another way
« Reply #35 on: May 16, 2018, 07:32:29 pm »

How much is a sheet of 3/4" birch B/BB plywood? And PU paint? And mesh metal? And handles? Etc etc.

Been there, done it. Never again.
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Mark Wilkinson

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Re: Gona try this another way
« Reply #36 on: May 16, 2018, 08:14:29 pm »

How much is a sheet of 3/4" birch B/BB plywood? And PU paint? And mesh metal? And handles? Etc etc.

Been there, done it. Never again.

3/4" 5x5 BB, $37 per sheet.  Duratex 1 gallon shipped $75. Handles, hardware, etc $50. 
Mesh for grills?  I agree, bane of building subs  ;)

I get where you're coming from...

And I've come to the conclusion that unless I'm trying to build a killer sub with great drivers... there's nothing to be saved..... & never again.

That said, if I want a killer sub and save alot of money, .....  I still think DIY rules.
And I guess maybe even more relevant, I enjoy the challenge of designing and building something that has the hope of more....
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David Winners

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Re: Gona try this another way
« Reply #37 on: May 16, 2018, 09:25:10 pm »


That said, if I want a killer sub and save alot of money, .....  I still think DIY rules.
And I guess maybe even more relevant, I enjoy the challenge of designing and building something that has the hope of more....

I decided to give 4 Keystones a shot for this reason. I'm not satisfying any riders. I want more sub for outdoor shows, but I can't justify a JTR or Danley rig quite yet.
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drew gandy

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Re: Gona try this another way
« Reply #38 on: July 25, 2018, 12:08:46 pm »

3/4" 5x5 BB, $37 per sheet. 

Where might I find this deal? 

Another thought for this unfortunate thread: Would it take more than one sheet to complete one subwoofer?  5x5 is 25 sq ft.  4x8 is 32 sq ft.  I'm expecting at least 40 sq ft for an "18" sub".

Lastly, although a manufacturer of quality transducers, I wouldn't necessarily set 18 Sound as the unique gold standard for bass drivers.  But if you do buy their products, you might get to deal with the best Sales and Operations Manager in the business, since 18 Sound was acquired by B&C earlier this year...   ;)
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Tim McCulloch

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Re: Gona try this another way
« Reply #39 on: July 25, 2018, 04:09:40 pm »

Where might I find this deal? 

Another thought for this unfortunate thread: Would it take more than one sheet to complete one subwoofer?  5x5 is 25 sq ft.  4x8 is 32 sq ft.  I'm expecting at least 40 sq ft for an "18" sub".

Lastly, although a manufacturer of quality transducers, I wouldn't necessarily set 18 Sound as the unique gold standard for bass drivers.  But if you do buy their products, you might get to deal with the best Sales and Operations Manager in the business, since 18 Sound was acquired by B&C earlier this year...   ;)

That clever Prescott fellow?
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