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broughd 3rd March 2008 10:14 AM

P.Audio / Jarcar OB driver choice
 
2 Attachment(s)
I'm looking at an OB. Driver availability (within cost constraints) is a bit of a limitation here, so I have narrowed down the choice a bit...

1) p.audio HP-15W 15" x2 or x4 per side

http://cgi.ebay.com.au/NEW-P-Audio-1...QQcmdZViewItem

2) jarcar 10" x8 or x9 per side (price reduced to $20ea)

http://www.jaycar.com.au/productView...=&SUBCATID=383

The p.audio has qts of .49 and the jarcar 0.775.

The jarcar simmed much better FR wise but the p.audio had higher output.

The jarcar works out to about half to cost of the p.audio even if using 9 drivers per side compared to 4 of the p.audio.

The 10 should have better highs but the 15 is more efficient lower qts so should move faster but would need eq.

My thoughts are that 10 seems like a good budget option whereas the 15 will probably yield better results but is going to cost a lot more.

I've attached a simulation comparing the options with 6db low pass @ 25hz on a 1.2m baffle. The SPL of 4 15s on this is 100db and 9 10s is 96db. The total SD is about the same but the XMAX of the 15s is probably a little higher.

Any thoughts on this appreciated!

cheers, DB

PeteMcK 3rd March 2008 08:42 PM

I've thought of use both of these for OB; I think from your sim the Jaycar would be easier to implement - but you'd better be quick, I think they're trying to run these out...
OTOH, if you're planning a trip to Thailand, the P Audio speakers are very cheap there (~$40)
FWIW, I've used the 12" Jaycar in OB, and I'm happy with the result
cheers
Pete McK

broughd 4th March 2008 01:27 AM

Quote:

Originally posted by PeteMcK
I've thought of use both of these for OB; I think from your sim the Jaycar would be easier to implement - but you'd better be quick, I think they're trying to run these out...
OTOH, if you're planning a trip to Thailand, the P Audio speakers are very cheap there (~$40)
FWIW, I've used the 12" Jaycar in OB, and I'm happy with the result
cheers
Pete McK

Thanks for your reply!

How did you find the 12" at low frequencies, does it seem to have decent xmax and does it run at higher excursions (say 8mm pp) without noise from the suspension and distortion?

cheers, DB

PeteMcK 4th March 2008 08:00 AM

Hi DB,
I don't use them very loud usually, but to my surprise (I beleived OBs were inefficient...) it can fill my quarter acre block with sound and annoy the neighbours... I use a little EQ on the amp tone controls for bass boost, and 1st order xover at around 200Hz.
As for the low end, it's ok, but to be honest, I prefer the solidity of a ported box...

broughd 4th March 2008 08:52 AM

Hi Pete

Its cool that you got good results with your system. How may drivers are you using per side?

From what I have read OB bass goes down to 35hz or so in room but you'll need something else under that if you want deep bass extension...


cheers, DB

PeteMcK 4th March 2008 09:16 PM

DB,
1x jaycar 12" + 1x 'no-name' 10" (small magnet =hi Q) for bass,
2x magnavox 6" + EV35T in MTM arrangement on a Visaton "no-box' style baffle, 46cm wide, basic 1st order series xover.
This was simply an experiment to use up a bunch of drivers I had lying around; It works pretty well as a TV sound system, but I've never bothered to refine it, it's not my main listening system...

jnb 5th March 2008 02:59 AM

Quote:

Originally posted by broughd
From what I have read OB bass goes down to 35hz or so in room but you'll need something else under that if you want deep bass extension...
You can achieve any lower cut off that you want. Unless you can manage a passive design, which you probably wouldn't easily do with the Jaycar, and which isn't easy to get deep bass from, then you'd probably want to EQ.

If you EQ, you no longer need a high Q driver, but you'll get any response you want, and you'll want to be able to move plenty of air.

broughd 5th March 2008 11:22 AM

Quote:

Originally posted by jnb


You can achieve any lower cut off that you want. Unless you can manage a passive design, which you probably wouldn't easily do with the Jaycar, and which isn't easy to get deep bass from, then you'd probably want to EQ.

If you EQ, you no longer need a high Q driver, but you'll get any response you want, and you'll want to be able to move plenty of air.


I guess... there is a limit to the low frequency response with IB though due to cancellation ... I'd be interested to know what sort of IB you would need to get a flat to 10hz !

cheers, DB

jnb 5th March 2008 11:42 AM

The response just rolls off, it doesn't just stop. I have had 20Hz flat from a 60cm square baffle. Aside from gain, it takes lots of cone excursion to get good levels.


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