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Author Topic: Simple Sub Question  (Read 3446 times)

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Simple Sub Question
« on: March 22, 2005, 01:56:10 pm »

Would people be at all opposed to using a triple-15" sub cabinet instead of a dual-18" sub cabinet if the triple-15" cabinet could get down to 20  Hz? Also, the 3x15" cabinet would have an impedance of 3.2 ohms.
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Geri O'Neil

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Re: Simple Sub Question
« Reply #1 on: March 22, 2005, 02:43:50 pm »

Simple answer. No.

Okay, a variant. They shouldn't.

ASSuming things are as you claim.

Geri O
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Rob Burgess

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Re: Simple Sub Question
« Reply #2 on: March 22, 2005, 03:14:26 pm »

In theory: No.  

In practice?  Well, how big are the triple 15's going to be?  How well do they truck pack?  What's the weight?  What's the sensitivity and power handling? (ie: how big an amp do I need?)

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Rob
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LesterSoundWorks

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Re: Simple Sub Question
« Reply #3 on: March 22, 2005, 08:46:25 pm »

Merlyn Speakers had a series called T-3  with 3- 18" speakers in each cabinet.  They went below 20hz easy. Very nice with bass.  
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Geri O'Neil

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Re: Simple Sub Question
« Reply #4 on: March 22, 2005, 09:25:22 pm »

Dwarf wrote on Tue, 22 March 2005 14:14

In theory: No.  




Why not (sincerely)?

How big of an amp one needs depends on the final power handling of the cabinet (not necessarily the summed power handling ability of the 3 drivers).

Honestly, there's lots more questions that need to be answered to fully consider the design. I mean, there's single-driver and double-driver cabinets that I wouldn't want for various reasons. The number of drivers in the box is but one part of the design. Isn't there an EV MT cabinet with 4 15s?

Geri O
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Baron Gray

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Re: Simple Sub Question
« Reply #5 on: March 22, 2005, 09:48:41 pm »

Geri O wrote on Wed, 23 March 2005 13:25

 Isn't there an EV MT cabinet with 4 15s?

Geri O


Hi Geri
I am not familiar with a 4X15 MT cabinet but I have some of the MT4L cabs that are 4X18".
Not a very easy cab to move around and with the new OH&S legislation there are not enough handles on the cab to allow it to be lifted without breaching the maximum weight per person limit!
These cabs are wired as two pairs of drivers per box.

Regards

Baron
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Chris Cowley

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Re: Simple Sub Question
« Reply #6 on: March 23, 2005, 01:07:51 am »

L'Acoustics Dvsub is a 3x15 design. Sound pretty good to me everytime I have heard/used them.

Likle any speaker cab - put the right drivers in, design the box right, put the correct amplifier on it an (last but not least) put the right signal in to it, then it will work well.
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Rob Burgess

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Re: Simple Sub Question
« Reply #7 on: March 23, 2005, 01:06:23 pm »

Geri O wrote on Tue, 22 March 2005 21:25

Dwarf wrote on Tue, 22 March 2005 14:14

In theory: No.  




Why not (sincerely)?



    Geri, you've lost me.  We both said that people shouldn't be opposed to using a 3x15 so your question has me confused.  

Geri O wrote on Tue, 22 March 2005 21:25

How big of an amp one needs depends on the final power handling of the cabinet (not necessarily the summed power handling ability of the 3 drivers).


    True.  Maybe I was getting ahead of things, it sounded like Rory was asking with a specific thing in mind.  And since he asked in the Lounge, where amp size is more a consideration than in the LAB, I thought to throw that into the pot.  If I'm (theoretically) being asked to give up my 2x18 cabs I need to be sure that they'll fit into my truck/van/basket on my bicycle and that I can power them at the local bar without needing to bring in a generator.  Yes I want to know how they sound and how reliable the components are and ... and ... and ..., but I was trying to keep my answer short Smile


Geri O wrote on Tue, 22 March 2005 21:25

Honestly, there's lots more questions that need to be answered to fully consider the design.


    I agree, but we haven't been given a design to ponder, just a vague 3x15 capable of 20Hz.  Realistically, any questions we ask are premature until we know what the design will be.

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Rob
 



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Tom Reid

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Re: Simple Sub Question
« Reply #8 on: March 23, 2005, 04:21:12 pm »

Baron wrote on Tue, 22 March 2005 20:48

Geri O wrote on Wed, 23 March 2005 13:25

 Isn't there an EV MT cabinet with 4 15s?

Geri O


Hi Geri
I am not familiar with a 4X15 MT cabinet but I have some of the MT4L cabs that are 4X18".
Not a very easy cab to move around and with the new OH&S legislation there are not enough handles on the cab to allow it to be lifted without breaching the maximum weight per person limit!
These cabs are wired as two pairs of drivers per box.

Regards

Baron

I always thought one of those MT cabs with 4 12" might be pretty cool if you could get it tuned low enough.
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Geri O'Neil

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Re: Simple Sub Question
« Reply #9 on: March 23, 2005, 04:37:42 pm »

Oops, my mistake. You are indeed correct, I mistook your answer as a negative response. Gotta luv them pre-daylight posts... Embarassed  Laughing

My apologies,
Geri O
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Ivan Beaver

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Re: Simple Sub Question
« Reply #10 on: March 23, 2005, 07:01:54 pm »

Nowadays many people are not so much concerned with what is in a cabinet as opposed to how well it performs.  Look at all the concert boxes that use 1" horns and small mids as opposed to the old days when 2" and 10/12" mids were the rule and nobody would consider a sub without 18" speakers.  So the size is not that big a deal (except in the car audio world)anymore.

My question would be (when you say it goes to 20hz) is how far down in level is 20hz and what type of sensitivity does the cabinet have.  Tom Danley's new company (Danley sound labs) is working on a new sub in which the -3dB point is around 17 Hz or so.  The overall sensitivity is going to be a little low for PA work (around 95dB 1 watt @ 20 Hz), but it would still have many uses.

What type cabinet were you going to use?

Ivan Beaver
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Re: Simple Sub Question
« Reply #11 on: March 23, 2005, 07:51:00 pm »

Geri O wrote on Wed, 23 March 2005 16:37

Oops, my mistake. You are indeed correct, I mistook your answer as a negative response.


    Yeah, "no" is usually a negative answer.  Except sometimes  Laughing

Geri O wrote on Wed, 23 March 2005 16:37


My apologies,
Geri O


    No apologies necessary, go have a Barqs and put it on my tab  Cool

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Rob
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Re: Simple Sub Question
« Reply #12 on: March 23, 2005, 08:09:42 pm »

My thought was for the future when (only in my dreams, probably)  I have my own speaker company, BHFSpeakers, and the professional division BHFProfessional would make a 3x15" vented cabinet loaded with 3x Ciare 15.00SW. With recent changes, the SW range can now handle 1250 watts AES, up from 1000 watts AES so you could definitely pump in the power (3,750w into 3.2 ohms). The tuning point would be kind of low and the major caveat that comes to mind is that you wouldn't want to try and use them outdoors. I wanted to test the waters and see whether or not people would trust a cabinet that employed three 15" woofers instead of two 18" woofers. I was inspired by a triple-15" cabinet made by Stage Accompany.
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Geri O'Neil

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Re: Simple Sub Question
« Reply #13 on: March 23, 2005, 08:31:40 pm »

Dwarf wrote on Wed, 23 March 2005 18:51

 No apologies necessary, go have a Barqs and put it on my tab  Cool

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Rob



NOW yer talkin!
Thanx!
Geri O
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Mark Seaton

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Re: Simple Sub Question
« Reply #14 on: March 30, 2005, 02:21:49 pm »

BHFProfessional wrote on Wed, 23 March 2005 19:09

My thought was for the future when (only in my dreams, probably)  I have my own speaker company, BHFSpeakers, and the professional division BHFProfessional would make a 3x15" vented cabinet loaded with 3x Ciare 15.00SW. With recent changes, the SW range can now handle 1250 watts AES, up from 1000 watts AES so you could definitely pump in the power (3,750w into 3.2 ohms). The tuning point would be kind of low and the major caveat that comes to mind is that you wouldn't want to try and use them outdoors. I wanted to test the waters and see whether or not people would trust a cabinet that employed three 15" woofers instead of two 18" woofers. I was inspired by a triple-15" cabinet made by Stage Accompany.


Hi Rory,

Unfortunately we have to work within the limits imposed by physics.  Hoffman's iron law is always at work.  Even when we can get ahead of it's predictions with highly optomized bandpass designs, we are still subject to the same trade offs in box volume and sensitivity as related to low frequency extension.  A rule of thumb Tom Danley loves to remind me of is that for a given box volume with an optimized design, you take a hit of 9dB! for every octave you want to push the cut-off lower.

Regards,
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Mike {AB} Butler

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Re: Simple Sub Question
« Reply #15 on: March 31, 2005, 09:32:26 am »

Mark Seaton wrote on Wed, 30 March 2005 11:21


Hi Rory,

Unfortunately we have to work within the limits imposed by physics.  Hoffman's iron law is always at work.  Even when we can get ahead of it's predictions with highly optomized bandpass designs, we are still subject to the same trade offs in box volume and sensitivity as related to low frequency extension.  A rule of thumb Tom Danley loves to remind me of is that for a given box volume with an optimized design, you take a hit of 9dB! for every octave you want to push the cut-off lower.

Regards,


Mark,
Spot on. My personal experience in this was some years back I took a bandpass design I had done, and tried redesigning the box to get another 1/2 an octave bottom out of it. I increased the volume and retuned both ports (6th order bandpass). Result? Much smoother, better low frequency cutoff (using the same woof), BUT a huge -10 dB hit!
Your advice to Rory is correct.. Simulations won't always show the final actual efficiency of the box.
Thanks and Regards,
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