La Scala Bass Bin Frequency Response

[sootshe]

Going to try some of the dual phase plug K55's....they are supposed to be the goods.

Probably take a couple of weeks to get here, but I will post thoughts after listening. []

[SpyderAudio]

I use my LaScala bins for the mid range in my 3 way system. they have a low crossover @ 125 Hz 36 db NTM and @ 2k on the top with a LR 24db slope. It integrates well with the JBJ 2395's with 2445 drivers low crossed @ 2.93k and a Bessel 12 db slope and a 12 db/oct upslope @ 10.9k +10db.

With a digital crossover you can smooth out the weird nodes in the upper portion of the box.

A screen shot of the curve.

http://www.flickr.com/photos/18946674@N08/5058778501/

[sootshe]

I use my LaScala bins for the mid range in my 3 way system. they have a low crossover @ 125 Hz 36 db NTM and @ 2k on the top with a LR 24db slope. It integrates well with the JBJ 2395's with 2445 drivers low crossed @ 2.93k and a Bessel 12 db slope and a 12 db/oct upslope @ 10.9k +10db.

 With a digital crossover you can smooth out the weird nodes in the upper portion of the box. 

A screen shot of the curve.

 http://www.flickr.com/photos/18946674@N08/5058778501/ 

Sorry, but I can't figure out what you're doing here........you're using the W bin as the mid range?..................so the bottom end is handled by something up to 125Hz?.........from 125Hz to 2K is the LS W Bin?.............then there's something else to 2.93K?.................then there must be something else to 10.9K?.................& then something else from 10.9K up?....................sorry but I can't get my head around this.[*-)]

[Rudy81]

I suspect he has an active crossover. My read is that he is using a 20hz to 125hz bass bin, the LaS from 125hz to 2kHz and a high driver from 2.93kHz on up. at 10.9k he is boosting the output by 10dB. In fact, that is where I am headed myself. I plan on using my RSW-15 from 20Hz to 50Hz, my DBB bass bin from 50-800Hz and my P. Audio top horn from 800Hz to 20kHz. But, that does require a high shelf above 13kHz or so to boost output to match everything. This is fairly easy to do with an active crossover and gives you a truly full range speaker.

Of course, I may be wrong. If in fact that is how he has it setup, then the LaS bass bin has no problem going to 2kHz.

[sootshe]

Rudy,

Yes, that's my take as well.........but that still leaves a gap between 2K & 2.9K???............Sometimes the more I read forum inputs the more confused I get............and just because someone uses a LS bass bin to 2 K doesn't mean it sounds right. []............your DBB set up should be awesome with the new bottom end............what was your low frequency limit running the DBB's on the bottom?

[Rudy81]

I suspect the 2-2.9kHz gap is somehow 'covered' by the type of crossover and the slope being used.

How it sounds, of course, we don't really know, but the user seems to like it. I have read in the past that many do not like having a bass bin go that high, particularly in a horn, due to vocals coming from the horn. That would be a particularly weird issue if you did not time align.

My DBB is tuned for right around 40Hz, so I plan on staying close to that for the top end on the subwoofer. As soon as I upgrade my crossover, I plan on setting it up that way to see how it sounds.

[SpyderAudio]

I guess more information would have helped. The LBR sits on a 16 cubic foot vented box with 2 18" EV drivers. The high horns in the LaScala are not used. The link to the Flickr picture is a screen shot of the digital crossover. It appears that there is a gap in the 2k region but the low slope on the high horn compliments the horn's response. It has been time aligned with Smaart live.

It was kind of a project to put together extra stuff around the house I don't use for sound reinforcement any more. With DSP processing you can accomplish a bunch of compensating with non matching equipment.

This is the crossover:

http://www.bssaudio.com/productpg.php?product_id=4

[sootshe]

 I guess more information would have helped.  The LBR sits on a 16 cubic foot vented box with 2 18" EV drivers. 

No lack of bottom end there then!!![]

[djk]

A very nice pair of Altec 292 just sold on eBay for only $256.

http://alteclansingunofficial.nlenet.net/publications/techletters/TL_231.pdf

A 292 is a 290 without the transformer cover.

As we can see on a 500hz radial horn it is useable to about 7Khz.

[CECAA850]

Slightly OT but a Lascala bass bin question. Does anyone know the frequency that causes the most vibration in the bin? Would that be the Fs of the bin? As opposed to bracing mine, I was going to high pass it and wondered if I would be spinning my wheels. I don't want to alter the stock look, but wanted to get rid of some of the resonance.

[Coytee]

If you look at the PEQ's for the JubeScala, there is a -7 db at 148Hz, Q=8.

I've got a little voice in the back of my head that says this was to kill that resonance. I think it was Pat that mentioned this long ago how he no longer has that issue now that he's biamping.

DX-38_settings_for_LaScala_(1_or_2)_LF_with_K402_&_K69.pdf

DX-38_settings_for_LaScala_(1_or_2)_LF_with_K402_&_K69.pdf

[CECAA850]

If you look at the PEQ's for the JubeScala, there is a -7 db at 148Hz, Q=8.

I've got a little voice in the back of my head that says this was to kill that resonance. I think it was Pat that mentioned this long ago how he no longer has that issue now that he's biamping.

If that's the case, high passing at 70 Hz won't accomplish what I'm trying to do. It may help, but if the resonance is around 148Hz I may need to look into some sort of external removable bracing. It's odd though, why try to reduce a resonance with a filter? You'd be kiling the vibration but also the music at that frequency.

[sfogg]

"It's odd though, why try to reduce a resonance with a filter? You'd be
kiling the vibration but also the music at that frequency."

The LaScala has a big peak right around there. Reducing that gets rid of some of the congestion/chesty sound it imparts on some material. When I EQed my LaScala's I had a similar PEQ in that area.

Shawn

[Islander]

It's odd though, why try to reduce a resonance with a filter? You'd be kiling the vibration but also the music at that frequency.

Coytee's little voice is right. []

The resonance augments the music. It's a peak. The filter is set to reduce the resonance, but not enough to cause a hole at the resonant frequency. It brings the response back to nearly flat.

There may be a time/phase issue caused by the resonance even though the peak is gone, but it's over such a narrow frequency range as to be inaudible. The EQing did improve the sound very noticeably on certain recordings. Bracing the bass horn might also improve the sound, but it would be difficult or impossible to do it as precisely as the digital processor does.

[sootshe]

FWIW.....Seems to me you're trying to overcome a problem with a band-aid...........why not just get rid of the resonance & be done with it.........you need to use constrained layer damping & braces to fully cure this.......you haven't really heard your La Scala's until you've done that........all the measurements in the world won't tell you what they sound like when the resonance is removed.....only that you've got a resonance!!

[CECAA850]

FWIW.....Seems to me you're trying to overcome a problem with a band-aid...........why not just get rid of the resonance & be done with it.........you need to use constrained layer damping & braces to fully cure this.......you haven't really heard your La Scala's until you've done that........all the measurements in the world won't tell you what they sound like when the resonance is removed.....only that you've got a resonance!!

I've actually set in front of my speakers with my head in the front of the mouth of the bass bin and applied inward pressure with my hands to the outside walls of the bins. You can actually hear a difference in the quality of the bass. It gets louder and clearer. It's not a huge difference, but it's definitely noticeable.

[sootshe]

quote]

 

I've actually set in front of my speakers with my head in the front of the mouth of the bass bin and applied inward pressure with my hands to the outside walls of the bins.  You can actually hear a difference in the quality of the bass.  It gets louder and clearer.  It's not a huge difference, but it's definitely noticeable.

Yes, after much searching I found the same thing......I already had braces fitted to my cabs, but they didn't come all the way to the front of the cabinet.....so I used an additional layer of 3/4" ply on both the external sides & the rear with a viscous glue, sound deadener, between them....problem cured.....and now the bottom end is ultra clean & powerful.....cleaned up the mids as well. The standard cabinet is simply not rigid enough to handle the forces generated by the woofer. Once you get rid of all the resonances all you get is pure, clean sound.[]

[ClaudeJ1]

"It gets wierd above 450hz or so, that would be my choice for an ES crossover."

I'm quite sure the Es400 network, which was designed for the Khorn, would work in the LaScala. It doesn't have quite as sharp a slope as the ES500 or ES600. I could easy do an ES450 design and post the schematic of it turns out to be the right place. I think it will limit your choice of drivers though. I don't know of any driver but the K55 that will run safely down at 400Hz on a 1-inch horn. I would definitely be scared to run an Altec 902 that low.

Al K.

I have 4 old Peavey 22A (aluminum) 1" throat drivers that all get down to 300 Hz. in a K-401 horn. I cross them at 500 to a Peavey FH-1 (like a bigger, better build, cheaper version of a LaScala bottom).

I'd be curious to see how they test with a your Tractrix horn.

[Islander]

FWIW.....Seems to me you're trying to overcome a problem with a band-aid...........why not just get rid of the resonance & be done with it.........you need to use constrained layer damping & braces to fully cure this.......you haven't really heard your La Scala's until you've done that........all the measurements in the world won't tell you what they sound like when the resonance is removed.....only that you've got a resonance!!

Perhaps the theoretically ideal solution would be to reinforce the bass horn, or build a new and more rigid one, as Klipsch did with the La Scala II. However, working with my stock horn and woofer, using the EQ settings tested and recommended by Roy Delgado, Klipsch's top engineer, provided the desired result: accurate and pleasant sound.

If you ever decide to do the JubScala conversion to your La Scalas, you'll have a good starting point with your reinforced bass bins. It's a fully engineered upgrade with no guesswork required and is a major step toward having the sound of Jubilees.

[sootshe]

FWIW.....Seems to me you're trying to overcome a problem with a band-aid...........why not just get rid of the resonance & be done with it.........you need to use constrained layer damping & braces to fully cure this.......you haven't really heard your La Scala's until you've done that........all the measurements in the world won't tell you what they sound like when the resonance is removed.....only that you've got a resonance!!

Perhaps the theoretically ideal solution would be to reinforce the bass horn, or build a new and more rigid one, as Klipsch did with the La Scala II.  However, working with my stock horn and woofer, using the EQ settings tested and recommended by Roy Delgado, Klipsch's top engineer, provided the desired result:  accurate and pleasant sound.

If you ever decide to do the JubScala conversion to your La Scalas, you'll have a good starting point with your reinforced bass bins.  It's a fully engineered upgrade with no guesswork required and is a major step toward having the sound of Jubilees.

After much researching, I'm pretty sure I'm going to go with the Great Plains Audio 390 drivers mated to an Altec Multicell Horn & keep running them 3 way. Looks like the Altec 805 multi is the best compromise between physical size & reaching down to the crossover point. I'll change the crossover to 500Hz ES & leave them 3 way. That should open up the mid range considerably, whilst tightening & cleaning up the bass.

HF Horns Multicellular Horns.pdf

HF Horns Multicellular Horns.pdf