La Scala bass bin modification question

[tigerwoodKhorns]

I am interested in this mod too. It seems that 40 hz is the target from some work that Gothover did.

I think he went for 35 hz and it did not sound as punchy. He raised it to 40 hz and posted that the bass was deeper and stil really punchy He used an add on with a slot port to the front.

[Marvel]

...ported it using 4x7.5" pvc

I believe most settled on 7 inches for the length of the tubes. The bass still had most of the snap with that length, although not quite as deep. The original mod was for 9 inch tubes if I remember correctly.

Bruce

[djk]

"I will say however the bass I get is not quite as clean as it was
before, but they could also be perception due to the fact it was quite
anemic before, I also replaced my woofers with Crites cast frames if
that in any way matters."

That seems correct. The deeper bass is no doubt energizing some room modes that were not causing problems previously. The Crites cast-frame driver with its lower Qts is better suited than the stock K33 for the vented mod. My original design was for the K43, which has a lower Qts than the K33.

"with my DX-38."

Try dialing in a notch at the floor-to-ceiling height, about 71hz for an 8 foot ceiling. Start with a 6dB cut and adjust the Q wider or narrower as needed.

"I believe most settled on 7 inches for the length of the tubes"

7.5 inches is close enough, it's also not a K33.

"I think he went for 35hz and it did not sound as punchy. He raised it
to 40 hz and posted that the bass was deeper and stil really punchy "

The original was ported to 31hz with a 10 inch length (with 6th order EQ applied) and the K43. The K33 users preferred the 7 inch length with the K33 (and are not using the EQ), which the computer model shows as tuned to 35hz (BB v6.0). With a little effort it would be easy to try different tunings and see what works best in your room, otherwise I would just cut them to 7 inches.

Hornresp shows the tuning frequency to be about 37.5hz with two 4 inch 7 inches long.

This is the Hornresp of the vented LaScala with a K43 in 2Pi (outside), no EQ. In room would add 3dB~5dB or so in the 40hz range, as much as 9dB in the 30hz region, and a big peak at the foor-to-ceiling height wavelength.

[tigerwoodKhorns]

So is a switch to a Crites woofer advisable if the stock woofer functions fine?

[ZombieWoof]

A guy over @ the AVS forum swears that if one does this mod to a LaScala then the LaScala is no longer a horn loaded bass bin ,

that by doing this mod is making the speaker into a bass reflex speaker , would you guys agree to that statement ???

I myself wouldn't think so , but I'm not anywhere near knowledgeable enough to say it wasn't ... I'm just asking you guys as you'd know better than me .

[kg4guy]

"I will say however the bass I get is not quite as clean as it was

before, but they could also be perception due to the fact it was quite

anemic before, I also replaced my woofers with Crites cast frames if

that in any way matters."

That seems correct. The deeper bass is no doubt energizing some room modes that were not causing problems previously. The Crites cast-frame driver with its lower Qts is better suited than the stock K33 for the vented mod. My original design was for the K43, which has a lower Qts than the K33.

"with my DX-38."

Try dialing in a notch at the floor-to-ceiling height, about 71hz for an 8 foot ceiling. Start with a 6dB cut and adjust the Q wider or narrower as needed.

"I believe most settled on 7 inches for the length of the tubes"

7.5 inches is close enough, it's also not a K33.

"I think he went for 35hz and it did not sound as punchy. He raised it

to 40 hz and posted that the bass was deeper and stil really punchy "

The original was ported to 31hz with a 10 inch length (with 6th order EQ applied) and the K43. The K33 users preferred the 7 inch length with the K33 (and are not using the EQ), which the computer model shows as tuned to 35hz (BB v6.0). With a little effort it would be easy to try different tunings and see what works best in your room, otherwise I would just cut them to 7 inches.

Hornresp shows the tuning frequency to be about 37.5hz with two 4 inch 7 inches long.

This is the Hornresp of the vented LaScala with a K43 in 2Pi (outside), no EQ. In room would add 3dB~5dB or so in the 40hz range, as much as 9dB in the 30hz region, and a big peak at the foor-to-ceiling height wavelength.

So just so I'm clear the ports should be 10" x 4" in diameter with the K-43 and 7" with the K-33?

[djk]

"A guy over @ the AVS forum swears that if one does this mod to a LaScala then the LaScala is no longer a horn loaded bass bin ,"

While that is absolutely true, it is also absolutely true that a stock LaScala is nothing more than a sealed box (acoustic suspension) below about 90hz.

The question is, do you want to have half-way decent bass (similar to the Cornwall) without having to add a subwoofer?

Technically I would term this a horn/reflex hybrid, many design examples of such exist and are nothing new. And of course Roy Delgado (chief engineer at Klipsch) holds the US 5898138 patent for a type of vented horn,

"The design merges the designs of a horn loudspeaker and bass
reflex loudspeaker to arrive at a loudspeaker having some of the benefits
of both designs."

"The vent is tuned to operate primarily at frequencies from
approximately 35 Hz to
approximately 80Hz. Because the woofer and vent are tuned to
different frequencies, the vent produces the vast majority of the sound
pressure level from approximately 35 Hz to approximately 80 Hz, and the
woofer produces the vast majority of the
sound pressure level from approximately 80 Hz to approximately 1000 Hz."

Some members have commented that the vented LaScala has bass similar to the Cornwall, but with more 'punch'.

[djk]

"So just so I'm clear the ports should be 10" x 4" in diameter with the K-43 and 7" with the K-33?"

I would certainly try it. Remember though, I did use 6th order EQ.

I do have a friend that is using 7.5" posts with his K43s and no EQ and he is very pleased with the sound. He recently sold his empty K-horn bottoms to another forum member.

He is currently building a quad 8 push-pull plenum to replace the K43 in the LaScala, and will be building a pair of 28hz PPSL to replace his K-horn bottoms. He is using the same 8s in the house in a 28hz PPSL design for his theater system. He has a couple of pair of Thiel speakers for sale, CS2 and SCS (I think).

[ZombieWoof]

"A guy over @ the AVS forum swears that if one does this mod to a LaScala then the LaScala is no longer a horn loaded bass bin ,"

While that is absolutely true, it is also absolutely true that a stock LaScala is nothing more than a sealed box (acoustic suspension) below about 90hz.

The question is, do you want to have half-way decent bass (similar to the Cornwall) without having to add a subwoofer?

Technically I would term this a horn/reflex hybrid, many design examples of such exist and are nothing new. And of course Roy Delgado (chief engineer at Klipsch) holds the US 5898138 patent for a type of vented horn,

"The design merges the designs of a horn loudspeaker and bass
reflex loudspeaker to arrive at a loudspeaker having some of the benefits
of both designs."

"The vent is tuned to operate primarily at frequencies from
approximately 35 Hz to
approximately 80Hz. Because the woofer and vent are tuned to
different frequencies, the vent produces the vast majority of the sound
pressure level from approximately 35 Hz to approximately 80 Hz, and the
woofer produces the vast majority of the
sound pressure level from approximately 80 Hz to approximately 1000 Hz."

Some members have commented that the vented LaScala has bass similar to the Cornwall, but with more 'punch'.

Thanx djk,

I understand now [Y]

Mike

[tigerwoodKhorns]

So just so I'm clear the ports should be 10" x 4" in diameter with the K-43 and 7" with the K-33?

Check out this thread:

http://forums.klipsch.com/forums/t/135733.aspx?PageIndex=2

Gothover uses the top hat volume and adds an add on piece to the bottom for the port. He also uses the Crites woofers. He explains the smaller port tuning higher somewhere in the thread.

I think his ports equal the two 7" ports.

[kg4guy]

Yes I have been through that post a few times it's a amazing job Dave did on those La scala's. Will porting these have any affects on the classic slam the La scala's have ?

[tigerwoodKhorns]

Yea, he did a great job. I plan on leaving my top hats empty, but adding the bottom slot port still may work as the volume is about the same.

When it cools off I will probably take a ride to LA on my motorcycle. I should see if Dave accepts visitors.

Per his post, these still have the slam. Apparently, they were not as tight with the lower tuning. Then he raised to 40 HZ (or so) and the speed an dimpact came back.

[kg4guy]

"So just so I'm clear the ports should be 10" x 4" in diameter with the K-43 and 7" with the K-33?"

I would certainly try it. Remember though, I did use 6th order EQ.

I do have a friend that is using 7.5" posts with his K43s and no EQ and he is very pleased with the sound. He recently sold his empty K-horn bottoms to another forum member.

He is currently building a quad 8 push-pull plenum to replace the K43 in the LaScala, and will be building a pair of 28hz PPSL to replace his K-horn bottoms. He is using the same 8s in the house in a 28hz PPSL design for his theater system. He has a couple of pair of Thiel speakers for sale, CS2 and SCS (I think).

Did he port out the tops or did he build a bottom unit I think I will router out the tops of my La scala's and use the 7.5" port lengths with the K-43"s if I decide to do this ?

[djk]

He went out the back of the top section.

[kg4guy]

Thank you Dennis I'm going to do this tomorrow.

[kg4guy]

Well my hat is of to djk I finished one of my LSI's bass reflex today I went with the top mod and am amazed I wanted to do them one at a time so I could do a A&B test there is a big difference in the LF I went with 7 1/2" ports couldn't be happier fast and tight .

[kg4guy]

I figured I would add some photos on how to do this on the LSI's as it is very easy. I had already removed the front face on my LSI's to install new Faital Tractrix horn I got from Bob Crites I will add I needed to fabricated a adapter for it to fit on this horn but with the Selenium adapter and some PVC it's fairly simple. First photo is after I took my jigsaw and cut out a majority of the top of the dog house then I used a flush trim bit and routed the rest of it out.

[kg4guy]

The ports I got from the local packing store a few months ago they are thick cardboard you could use PVC and maybe a better choice but this works fine I glued it with the some good glue.Very easy to trace around the back board of the LSI after it is removed and then a circle jig to router out the 4" port holes.

[kg4guy]

I added a small piece of wood across the top back to brace the port board better.

[kg4guy]

Here is a internal shot to see also