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nearly ready for Pi speakers in the UK! [message #51608]

Sat, 15 December 2007 18:44

PaulW
Messages: 71
Registered: May 2009
Location: UK

Viscount

Hi Wayne,

Early this year I discussed here the potential for using your speakers with my Bottlehead Paramours in a dedicated room I was having built. Well its now built

(just decorating to do) unfortunately due to some constraints its ended up a bit smaller than I would have liked. Final dimensions are 17ft 6in(L) x 12ft 4in(W) x 8ft 6in(H) however I've also had a cloakroom installed (for those long listening/movie sessions) which has reduced the length by 3 ft for half the width.

Now initially I was goiing to go for a pair of Stage or Premium 7's (is the only difference here the 15in Killomax driver?) but given the final dimensions of the room could you advise on the suitability of these, or would I be better off going for another model?

thanks

Paul

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Re: nearly ready for Pi speakers in the UK! [message #51610 is a reply to message #51608]

Sun, 16 December 2007 09:31

Wayne Parham
Messages: 18682
Registered: January 2001

Illuminati (33rd Degree)

I'd stick with the cornerhorns. Go with the Professional Series seven π if you can.

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Re: nearly ready for Pi speakers in the UK! [message #51611 is a reply to message #51610]

Sun, 16 December 2007 13:12

PaulW
Messages: 71
Registered: May 2009
Location: UK

Viscount

Unfortunately the Professional 7's are more than I would be willing to commit to, so its going to have to be Stage or Premium seven's. Would the Kilomax 15 provide better control than the Omega 15 or are there more fundamental differences between the two 7's?

Paul.

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Re: nearly ready for Pi speakers in the UK! [message #51612 is a reply to message #51611]

Mon, 17 December 2007 08:51

Matts
Messages: 359
Registered: May 2009

Grand Master

I built some Stage 4's w/ the Omega 15's a few yrs ago, and really liked them a lot. I liked them so much that I had some JBL 2226's lying around for a year and didn't feel any need to put them in instead of the Omegas. However, after I did put them in, there was enough difference that I wished I had skipped the Omegas.... The Omega is a good speaker, especially for the money. You won't be disappointed with them, but the 2226 is a step-up. It just depends on your budget.

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Re: nearly ready for Pi speakers in the UK! [message #51613 is a reply to message #51612]

Mon, 17 December 2007 13:03

Wayne Parham
Messages: 18682
Registered: January 2001

Illuminati (33rd Degree)

The Kilomax 15 has an edge over the Omega 15 when used above a couple hundred watts. At high power levels, the Kilomax is more robust and doesn't shift electro-mechanical parameters as much. At lower power levels, I prefer the Omega though.

In either case, the JBL 2226 is a better driver having a shorting ring in the motor to reduce distortion. The midbass and lower midrange is clearer as a result. The Eminence woofers sound nice, to me they're better sounding than any other traditional ferrite woofers. But I can really hear the difference in the JBL's with their shorting rings. The harmonics generated from bass and midbass fall squarely in the midrange and that's the most noticeable range for them to be.

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Re: nearly ready for Pi speakers in the UK! [message #51614 is a reply to message #51613]

Mon, 17 December 2007 13:17

Matts
Messages: 359
Registered: May 2009

Grand Master

"above a couple hundred watts." haha- no knowledge about this- I use them with SET, so they get 3.5 watts, maybe 4 on a good day with a wind blowing the power lines.

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looks like its going to be the Stage 7's then... [message #51615 is a reply to message #51613]

Mon, 17 December 2007 15:38

PaulW
Messages: 71
Registered: May 2009
Location: UK

Viscount

...as I can't run to the JBL 2226's and only have just over 3 watts on tap, so decision made, I'll be mailing you in the new year about whether to source the larger drivers locally, vs. shipping from the US.

Thanks for the help so far - and have a good Christmas and New year.

Now back to the decorating

Paul

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Re: nearly ready for Pi speakers in the UK! [message #51616 is a reply to message #51613]

Mon, 17 December 2007 19:01

Chris R.
Messages: 82
Registered: May 2009

Viscount

Wayne,

Not knocking JBL, but with the corner horns crossing at 200Hz-300Hz, are you into the range where the shorting ring works?
I have some JBL music instrument speakers that sound *significantly* better than the Eminence drives I have, and those don't have
the shorting rings and what not. JBL really has it going on.
Chris

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Cornerhorn woofers [message #51617 is a reply to message #51616]

Mon, 17 December 2007 21:41

Wayne Parham
Messages: 18682
Registered: January 2001

Illuminati (33rd Degree)

JBL takes care to machine the gap so the flux lines are symmetrical around the voice coil. In addition, their older alnico drivers had reduced distortion because alnico resists flux modulation. Their newer drivers with ferrite magnets use shorting rings and boast even lower distortion. Newer still are their woofers with push-pull drive using dual voice coils and they provide even better performance.

JBL Magnet Structures, Comparing alnico and ferrite with and without shorting rings

What I've found is that shorting rings work best as frequency rises. They just don't work well at subwoofer frequencies. Push-pull works better below about 50Hz. I have never seen a woofer with a shorting ring that was effective below 50Hz. Depending on the woofer, some shorting rings don't do much below 100Hz or even 150Hz. But the JBL 22xx series woofers provide reduced distortion starting around 50Hz to 100Hz.

With a first-order crossover at 250Hz, there is plenty of overlap between the mid and bass. In this design, it's important to have good clean output from the woofer up through 500Hz or so. That's a decade of output from where the JBL shorting ring starts to work.

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