doubling driver numbers/spl gains?

[SpeakerBob]

Hello all,

I know if you have 1 driver, say 93Db , powered by its own amp (1 watt), and then add a second powered by its own amp you end up with a 6Db gain. What happens if you continue this as in the attatchment below?

Reason I'm asking is that after I finish my current speaker project, I'm looking to do some linkwitz-transform adjusted subs, but don't want to shove loads of power into the drivers. If I can get a highish (112 - 115 spl) at fairly low watts this would be nice

Thanks for any thoughts.

Rob

 

[planet10]

I know if you have 1 driver, say 93Db , powered by its own amp (1 watt), and then add a second powered by its own amp you end up with a 6Db gain. What happens if you continue this as in the attatchment below?

Very well worded Rob. The separate amp gets around that issue.

Every doubling of the number of speaker/amps gives you 6 dB. There is also a small potential gain with mutual coupling (small compared to the rest)

dave

 

[f4ier]

A rough estimate of the gain is 20*log10(number of drivers)

 

[SpeakerBob]

Hi Dave,

Cheers for the response. I've been looking at the peerless xls 830500 as it has a good reputation, but I'd rather use more sensitive speakers, lower power amps.

The peerless will go flat to 20Hz if I boost the bottom end by 15Db (90 Db flat@32watts), and if I pair up and use 6 amps/speakers I'll get a theoretical 108Db @ 32 watts. Thats pretty impressive.

If I go F-3 at 20Hz, I'd get 111Db@ 32 watts.

I reckon these would sound very clean and low distortion at normal listening levels. I've read for home theater you calibrate for a peak of around 112/115Db on the sub.

Maybe I should look for more sensitive subs, or 15" models ?

hehehe cheers

Rob


btw, still glueing layers together at work, but one bass cab is waiting for its veneer now.

 

[SpeakerBob]

""A rough estimate of the gain is 20*log10(number of drivers)""

Cool - I'll dig out my calculator.

Cheers

Rob

 

[roddyama]

Hi Rob,

Since you're talkin' SPL in the bass region, here's a Keltic thread that might help to shead a little more light on the subject.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=5668&highlight=SPL+Volume+Chart

Hope it helps,
Rodd Yamashita

 

[SpeakerBob]

Hi Rodd,

Thanks for the link - I did do a search but this didn't show up

The peerless I'm talking about are used by Linkwitz' Thor subwoofers, and as such theres a lot of info on his site:

http://www.linkwitzlab.com/thor-estim.htm

He seems to think that I should get about 108Db from one driver, in room @ 20Hz( ), so if I go by these stats, then 4 would be overkill, but superb!, and they'd all be underdriven too..(less distortion)

Cheers

Rob

 

[planet10]

I'll get a theoretical 108Db @ 32 watts.

I don't know about theory, but my room loaded Shiva, driven by 2x20 W did plenty well on movies. We'll see how it does when i get it in the new setup (it won't be as heavily room loaded).

That is only tempoary with 2 x Lamba/Strykw SEAE1024 & enclosure bits stitting downstairs. I'll be able to throw another 2 x 20 W at it too.

I've heard good things about the Peerless.

dave

 

[SpeakerBob]

Hi again Dave,

I was interested in the shiva, but I'm "pretty" sure its not availabe in the UK. The peerless definitely is (at a price )

Looking at the room gain charts that kelticwizard posted, I reckon my best bet would be to measure the sub in room, and add enough (if any) equalization to make it flat.

Coccolino (Christoph) suggested that I use the Linkwitz transform circuit on my stereo speakers I'm building, and at 1st I thought no, but now I'm quite taken with the idea (means I won't have to use a sub with music)

The sub(s) would be purely for movies.

I've just put my home up for sale, and will be moving to a house with a dedicated av room, so I can use as many subs as I want, without imposing on the room.(or the neighbours )

Rob

 

[planet10]

I was interested in the shiva, but I'm "pretty" sure its not availabe in the UK. The peerless definitely is (at a price )

Makes sense. Ignoring time to get to & thru the airport, Adire is a 20 min airplane ride away from me, and Peerless can't be much further from you. I actually drove down (when i could still sneak into the US) and picked mine up (and a 16 ft length of 1/2" wall 8" square tube for use in amp chassis).

Lambda thou is in Florida.

dave

 

[daatkins]

Rob,
I haven't found a source for the Shiva in the UK either but the site....
http://www.adireaudio.co.uk

... has been registered so Adire might be arranging a UK-based dealer. Let's hope so!

Nice one,
David

 

[SpeakerBob]

Hi David,

It would be nice if Adire came to the UK, but we can guarantee that the good old fashioned UK pricing fix will kick in (£ for $), so's they won't be as cheap as they look now..


I've just been looking at the tempest stats...very nice!, however, do people rate them as high as the peerless for sound quality ?

I've just put them through winISD and they'd (theoretically)be great in the setup I am looking towards.

3 x 15" sealed, eq flat to 20Hz..looks promising I reckon they'd price quite fairly if I imported them one at a time aswell.

Rob

 

[roddyama]

By RobWells
...then 4 would be overkill...

Rob,

Not over kill, just less excursion and lower distortion.

By Planet10
(when i could still sneak into the US)

What happened Dave, did the border patrol get wise to you.

Rodd Yamashita

 

[argo]

Hi Rob,

May be you will find some interesting bass drivers sold by BK elekctronics UK http://www.bkelec.com . One to recommend could be Alcone AC 12 SW-4. I havent used that particalar driver myself but the two smaller 10 inch Alcones whitch I have in sealed boxes produce really loud, clean and musical bass.


Argo

An externally hosted image should be here but it was not working when we last tested it.

 

[planet10]

I've just been looking at the tempest stats...very nice!, however, do people rate them as high as the peerless for sound quality ?

Just based on gut feel if i had to choose between Peerless & Adire on sound quality, i think i'd go with the Peerless.

dave

 

[planet10]

I've just put them through winISD and they'd (theoretically)be great in the setup I am looking towards.

You have to be quite careful with theory. Often, due to room lift you get way more bottom than you were counting on.

dave

 

[BrianGT]

If you look at the Shiva white paper, they have information about using multiple shivas. The paper is at:
http://www.adireaudio.com/Files/ShivaWhitePaper-V2.PDF

Here is a screenshot of the information that I am talking about. This goes from 1 to 4.

--
Brian

 

[planet10]

What happened Dave, did the border patrol get wise to you.

In 1984 i got busted for growing pot -- they got 23 g wet. US has zero tolerance, and unlike the rest of the world doesn't recognise my pardon. So if they check me at the border the least i get is turned at the border -- the worst is way worse. And since they got the guy coming from Victoria with the explosives in his trunk, it is likely i'd get stopped, and since 911 just forget it.

dave

 

[planet10]

One to recommend could be Alcone AC 12 SW-4. I havent used that particalar driver myself but the two smaller 10 inch Alcones whitch I have in sealed boxes produce really loud, clean and musical bass.

At least one of out members, peterr, would concurr. A sneak preview of his Alcone T-Line -- this article is still beta with some missing bits (mostly the drawings).

dave

 

[BrianGT]

If I can get a highish (112 - 115 spl) at fairly low watts this would be nice

I did a calculation earlier, and if you are using the shiva subwoofer, it would take 160 shiva subwoofers in a 4 ohm configuration to obtain 120.24 dB...

--
Brian