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Message started by dank on 07/13/07 at 21:39:53

Title: Interesting twist for an Imperial
Post by dank on 07/13/07 at 21:39:53

This project started out as a "what if" question.  One thing led to another, and the results are interesting enough to share.



What you are looking at is a standard Decware Imperial with an 18" JBL K151 and an 8" Audio Nirvana "standard 8".  The JBL is a 200 watt, 35-2000 hz, 99 db efficient  "bass instrument" speaker, while the Audio Nirvana is a 30 watt, 40-17000 hz, 95 db efficient full range speaker.  What I think is so amazing about this, is the amount of bass that comes out while the mids and highs stay really crisp and alive.  I started out running both speakers full range, but quickly realized I had to throw a crossover in to give the poor 30 watt Audio Nirvana a break.  The only thing I had lying around was a 500 hz 12db/octave 2-way, and I suspect a better crossover frequency could be found, but this works quite well.

Below is the frequency responce to white noise when the amplifier is set to flat:



Below is the frequency responce to pink noise when the amplifier is set to flat:



Being the bass enthusiast that I am, I usually like to turn the bass up to just under 3/4 and turn the loudness on.
Below is the frequency responce to white noise when the amplifier is set to more bass:



Below is the frequency responce to pink noise when the amplifier is set to more bass:



By the way, thats a pair of Pro12's in the background in case anyone's interested, and there's a matching Imperial to the left just out of camera range.

DanK



Title: Re: Interesting twist for an Imperial
Post by ZYGI on 07/13/07 at 23:41:15

Dan,

 Thats good new, but I have to ask, whats the pyramidal shaped cabinet just to the right of the Imp. Your not try to build a pair of RL-3's are you????


  Maybe you could bring these to Decfest, you and your wife are planning on coming down again.

BobZ

Title: Re: Interesting twist for an Imperial
Post by dank on 07/16/07 at 16:15:58

No, its not an RL-3...It was an exercise to see if I could build a pyramid shape more than anything else, pretty easy actually.  I believe the one in the picture has a 15" downfiring sub in it.  I have since decided that I like my sub in a third box so it can be placed without regard to where the main speakers are.

We hope to be at Decfest '07, but the Imperials will not.  500 miles in an open pickup truck with no A/C, no CD, and about 12 mpg would be painful.

DanK

Title: Re: Interesting twist for an Imperial
Post by Valiant on 07/17/07 at 01:53:47

Great work DanK,
other than the 12dB crossover, are there any precautions taken to 'isolate' the Nirvana from the JBL, i.e. does it reside in its own cabinet, or does it feed the horn as is the usual case. What are your thoughts?
Cheers
Gaz

Title: Re: Interesting twist for an Imperial
Post by dank on 07/17/07 at 23:27:53

As in the standard Imperial, both speakers are open to the horn, and there is a partition in the compression chamber between the speakers.  You can see the Audio Nirvana cone move on some of the louder bass notes, and I'm sure that's from the acoustic energy of the K151 feeding back into the Audio Nirvana side of the compression chamber.  I have not been able to hear anything bad due to this effect, however.

DanK

Title: Re: Interesting twist for an Imperial
Post by morpheous85 on 09/14/07 at 15:35:29

The movement sounds like it'd loose some efficency. Perhaps a 6db/octave would reduce this as the speaker is now countering the effect? In my WO (which also shares a chamber), I accidentally ran it with one speaker unplugged. It sounded fine at low levels, but as I turned it up, everything got really mushy and compressed.

Just a thought.

Jason

Title: Re: Interesting twist for an Imperial
Post by Valiant on 12/10/07 at 14:11:16

Hey Dank,
Just bringing your article back up, cause as you may see, I maybe
trying an interesting twist of my own.

I'm interested to know how you made your sound evaluation, i.e. where
do you place your mike when you are doing a spectrum analysis of the Imperial?

Cheers

Gaz

Title: Re: Interesting twist for an Imperial
Post by dank on 12/10/07 at 17:11:18


Valiant wrote on 12/10/07 at 14:11:16:
I'm interested to know how you made your sound evaluation, i.e. where
do you place your mike when you are doing a spectrum analysis of the Imperial?

Cheers

Gaz



Hi Gaz

Nothing real special about mic placement.  I'm limited by my 16x24 shop (with too much stuff in it).  I generally just try and place the mic where I would sit (sweet spot).   I also try to use it only for comparison purposes not absolute, although sometimes its hard to do that (like when you get a really good looking graph).  I'm using WinAudioMLS software (search for WinAudioMLS if interested) that I've been very happy with.

Dan

Title: Re: Interesting twist for an Imperial
Post by 60_and_up on 12/11/07 at 00:39:36

i see pro 12ms  8-)

Title: Re: Interesting twist for an Imperial
Post by dank on 12/12/07 at 14:46:40


60_and_up wrote on 12/11/07 at 00:39:36:
i see pro 12ms  8-)



Yes, they are mentioned in the initial post.  A friend who does DJ work is now using 4 of the pro12m's as his mains and swears by them.  He has tried all kinds of stuff in the past and has finally settled in on 4 x pro12m.  Two are loaded with the 12" goldwood pro knockoff available from cheaplights.com for $74, considerably less than the goldwood.  The other two are loaded with a 12" Pioneer musical instrument speaker that I had lying around (Parts Express 290-142).  The 2 sets of 2 different speakers seem to work well togeather.

Dan

Title: Re: Interesting twist for an Imperial
Post by weasel2htm on 12/16/07 at 04:47:38


dank wrote on 12/12/07 at 14:46:40:



Yes, they are mentioned in the initial post.  A friend who does DJ work is now using 4 of the pro12m's as his mains and swears by them.  He has tried all kinds of stuff in the past and has finally settled in on 4 x pro12m.  Two are loaded with the 12" goldwood pro knockoff available from cheaplights.com for $74, considerably less than the goldwood.  The other two are loaded with a 12" Pioneer musical instrument speaker that I had lying around (Parts Express 290-142).  The 2 sets of 2 different speakers seem to work well togeather.

Dan

Just a quick curiosity question, what is he using for subs, if anything.

Title: Re: Interesting twist for an Imperial
Post by 60_and_up on 12/16/07 at 16:55:35


dank wrote on 12/12/07 at 14:46:40:



Yes, they are mentioned in the initial post.  A friend who does DJ work is now using 4 of the pro12m's as his mains and swears by them.  He has tried all kinds of stuff in the past and has finally settled in on 4 x pro12m.  Two are loaded with the 12" goldwood pro knockoff available from cheaplights.com for $74, considerably less than the goldwood.  The other two are loaded with a 12" Pioneer musical instrument speaker that I had lying around (Parts Express 290-142).  The 2 sets of 2 different speakers seem to work well togeather.

Dan


my 12 ms are my first high volume sq speaker and i like em a lot.

have you tried your imperial as a sub only and use the 12m as the mains? < thats gonna get loud and sound tight.

Title: Re: Interesting twist for an Imperial
Post by dank on 12/17/07 at 13:46:22


weasel2htm wrote on 12/16/07 at 04:47:38:
Just a quick curiosity question, what is he using for subs, if anything.


He usually uses a pair of folded horn Cerwin Vega Earthquake clones with a single 18 each and then a pair of ported boxes that have dual 15's each (I think).  The ported boxes are short throw and the folded hornes are long throw and he's convinced you need both.  Its possible the Imperials could do both, but they are just too darn big and heavy to move around.

Dan

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