DIY La Scala mid upgrade options

[No.4]

Greetings. In July I set out to build a pair of DIY La Scalas that utilized several upgrades detailed on the forum right from the get go. My goal was to enhance the designs performance while utilizing low budget "first step" upgrades. While not every element of the design was upgraded from stock all the parts are new, and mostly sourced from Bob Crites. Thank you again Bob.

The parts used for this build.

Crites Ct-125

Crites A/4500

Atlas PD-5VH

K-401

Kappa 15c

The bass bins are 1.5 inch mdf, solid and really, really heavy

Nothing too out of the ordinary, however I wanted to build the bottom end right from the start because I knew I would probably end up following the endless upgrade path on the top. My initial listen was great, the speakers are very different from any other and they are very revealing. After 6 weeks of listening and going through my collection I have been noticing some issues with the mids. I know, I was warned. I am noticing harshness that seems like distortion at times from certain recordings. Some are worse than others. This I assume is a pitfall of high sensitivity. Lately I feel I am just listening for this (my fault).

Anyway, this is probably where the upgrade illness starts? I am looking at alternatives to the k401.

For now I would like to keep the pd-5vh driver, for now. I would also like to keep the a/4500 network for now too. The options I have found are few, but some seem to have a large following.

Eliptrac 400

Eliptrac 240 (don't know if this is appropriate but I don't have size limitations)

Fastrac la scala

Volti fc260 (not really sure if this is available or what it costs)

Altec 511b

EV hr60 (iirc these require crossover changes, not sure though)

Let me know if there are any other suitable options that I missed. I would much rather DIY a horn like the fastrac, but lately project time has been limited.

Keep in mind I will be listening near field and not at concert levels. I have a small 12x12 listening room that opens into a hallway on the back wall. My listening position is roughly 8 feet from the speakers. I am driving these speakers with a parks audio 6L6 clementine 5w, it's amazing how loud these get with 5w! These are just bass bins so I don't have anything size wise to work around for the tops. For those of you who have used these, what is my best option? Thanks.

[drboar]

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical. The baffle will improve the low end loading of the midhorn and also work as vibration sink for the horn. If that does not work out, then go to other horns.

[Guest David H]

Coyote, should be here any minute to recommend the K-510 and K-402.

 

Dave

[Guest David H]

Greetings. In July I set out to build a pair of DIY La Scalas that utilized several upgrades detailed on the forum right from the get go.

 

Welcome to the forums, your work on the bass bin is exceptional, keep it up.

 

Dave

[Full Range]

I would recommend the Eliptrac 400

However I may be biased because I use one in my setup

[Bubo]

Very cool!

[moray james]

while you are considering your options you might investigate experimenting with a Karlson K-Tube. I uses a double cutaway looks rather like a Bishop's cap. You can make a paper one for a cent piece of paper and some tape. I know that I won't be switching back to horns again. All that is required is to rol a paper tube with an O.D. the same as your driver exit opening I.D. a thin wire like the wire in a twist tie to make a hoop to keep the tube in a round shape after you make the necessary cutouts.. I set mine up parallel to th eflpoor at my seated ear level looking straight down each tube solid uncut sections of the K-Tube are in the horizontal plane. .I do plan to experiment with 25 PPI open cell foam plug for my tubes but they sound so good as simple paper tubes I have so little incentive to change what is working so well. What have you got to lose? Best regards Moray James.

[No.4]

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical

 

I would not have thought that the baffle would make that big of a difference. With a hand on the outer flare of the horn during offending passages there is little to no vibration and no movement, however it would not be difficult to route a few panels to experiment with this.

 

 

 

Greetings. In July I set out to build a pair of DIY La Scalas that utilized several upgrades detailed on the forum right from the get go.

 

Welcome to the forums, your work on the bass bin is exceptional, keep it up.

 

Dave

 

Thank you very much!

 

Very cool!

 

Thank you!

 

 

while you are considering your options you might investigate experimenting with a Karlson K-Tube. I uses a double cutaway looks rather like a Bishop's cap. You can make a paper one for a cent piece of paper and some tape. I know that I won't be switching back to horns again. All that is required is to rol a paper tube with an O.D. the same as your driver exit opening I.D. a thin wire like the wire in a twist tie to make a hoop to keep the tube in a round shape after you make the necessary cutouts.. I set mine up parallel to th eflpoor at my seated ear level looking straight down each tube solid uncut sections of the K-Tube are in the horizontal plane. .I do plan to experiment with 25 PPI open cell foam plug for my tubes but they sound so good as simple paper tubes I have so little incentive to change what is working so well. What have you got to lose? Best regards Moray James.

I forgot about these. Im sure I have more than enough of the materials laying around to construct these. Is there any formula or rule of thumb to follow to successfully build these?

[Chris A]

 

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical

 

I would not have thought that the baffle would make that big of a difference. With a hand on the outer flare of the horn during offending passages there is little to no vibration and no movement, however it would not be difficult to route a few panels to experiment with this.

 

Look at the bottom of page 3: https://community.klipsch.com/index.php?app=core&module=attach&section=attach&attach_id=8074

 

Also, try moving the K-77 tweeter back to the K-55 midrange compression driver plane and listen again: the soundstage should expand rather dramatically.

 

Coyote, should be here any minute to recommend the K-510 [or] K-402.

 

I recommend either of the two JubScala configurations. There's no comparison using either horn in a two-way with a good 2" compression driver-they will eclipse the stock La Scala 3-way configuration.  You'll need EQ for either controlled directivity horn (K-402 or K-510).

 

Chris

[Bubo]

while you are considering your options you might investigate experimenting with a Karlson K-Tube. I uses a double cutaway looks rather like a Bishop's cap. You can make a paper one for a cent piece of paper and some tape. I know that I won't be switching back to horns again. All that is required is to rol a paper tube with an O.D. the same as your driver exit opening I.D. a thin wire like the wire in a twist tie to make a hoop to keep the tube in a round shape after you make the necessary cutouts.. I set mine up parallel to th eflpoor at my seated ear level looking straight down each tube solid uncut sections of the K-Tube are in the horizontal plane. .I do plan to experiment with 25 PPI open cell foam plug for my tubes but they sound so good as simple paper tubes I have so little incentive to change what is working so well. What have you got to lose? Best regards Moray James.

 

 

1)  Videos on Youtube

 

PVC implementation

 

https://www.youtube.com/watch?v=27teQsB4bSU

 

Very Nice inc 1in measurements

 

https://www.youtube.com/watch?v=Hlf8NwIlQVA

 

Interview with Karlson on Radio

 

https://www.youtube.com/watch?v=AGSqs9zmNO4

 

2) Patents

 

Karlson open end waveguide

 

Karlson Patents

 

2816619

 

http://pdfpiw.uspto.gov/.piw?Docid=02816619&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2816619.PN.%2526OS%3DPN%2F2816619%2526RS%3DPN%2F2816619&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page

 

2896736

 

http://pdfpiw.uspto.gov/.piw?Docid=02896736&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2896736.PN.%2526OS%3DPN%2F2896736%2526RS%3DPN%2F2896736&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page

 

3540544

 

http://pdfpiw.uspto.gov/.piw?Docid=03540544&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D3540544.PN.%2526OS%3DPN%2F3540544%2526RS%3DPN%2F3540544&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page

 

This guy is interesting, has a different tapered slot and lists all the patents like his, but not the same inc Karlson

Be sure to use the images button on top.

 

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4&f=G&l=50&co1=AND&d=PALL&s1=3,540,544&OS=3,540,544&RS=3,540,544

 

3) Waveguide Patent Dimensional drawing

 

For some reason the forum won't let me link to images in other forums or on the web WTF????

 

4) DIY Forum Complete Discussion with Links to source data

 

http://www.diyaudio.com/forums/full-range/256176-what-real-inspiration-behind-karlson-coupler.html

 

http://www.talkbass.com/threads/karlson-speakers.52071/page-2

 

IG81 Did some build and took some measurements

 

http://www.diyaudio.com/forums/multi-way/3995-karlson-enclosure-12.html

 

freddi Huge Karlson Fan who owns K-Horns interesting write up like Tubes with PVC

 

http://www.diyaudio.com/forums/multi-way/3995-karlson-enclosure-11.html

 

"Transylvania Power Company's "The Tube" slotted waveguide (an adaptation of John Karlson's X15 internal waveguide from the 60's) is probably the best sounding waveguide in its range that I own and that includes DDS Pro90. The Tube can be approximated with a dime's worth of 1" schedule 40 pvc pipe using a Dremel cut wheel and a half ellipse slot. Drivers from B&C, Eminence and Selenium sound fine with this size 1 inch format Karlson waveguide. (BTW, Karlson patented the open end waveguide for microwave application)"

 

Slotted pipe discussion on DIY

http://www.diyaudio.com/forums/multi-way/273667-karlsons-slotted-pipe-tweeter.html

 

5. Website devoted to Karlson

 

http://home.planet.nl/~ulfman/

Edited November 2, 2015 by Bubo

[Marvel]

The K401 will sound pretty smooth on axis with the atlas driver. You may just try attenuating the mids about 3db and listen some more.

For sure, Chris' note to move the tweeter back to be in line with the mid driver will also help tremendously.

Bruce

[Bubo]

 

 

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical

 

I would not have thought that the baffle would make that big of a difference. With a hand on the outer flare of the horn during offending passages there is little to no vibration and no movement, however it would not be difficult to route a few panels to experiment with this.

 

Look at the bottom of page 3: https://community.klipsch.com/index.php?app=core&module=attach&section=attach&attach_id=8074

 

Also, try moving the K-77 tweeter back to the K-55 midrange compression driver plane and listen again: the soundstage should expand rather dramatically.

 

Coyote, should be here any minute to recommend the K-510 [or] K-402.

 

I recommend either of the two JubScala configurations. There's no comparison using either horn in a two-way with a good 2" compression driver-they will eclipse the stock La Scala 3-way configuration.  You'll need EQ for either controlled directivity horn (K-402 or K-510).

 

Chris

 

 

Chris,

 

On Horn Alignment of the Drivers, given the folded LaScalas Bass horn, should the K-55 and the K-77 Mid point on the Magnets both be moved approximately 12in behind the enclosure. I'm estimating a 4in gap between the doghouse and the rear of the cabinet; plus the distance from the Dog house rear wall to the mid-point on the Woofer magnet?

 

In other words, if the LaScala Bass Bin were unfolded, how long would it be? I'm guessing 12 in. longer than folded.

 

These are measurements I am also interested in. I think this is one of the things JBL got right on their best speakers and on some of the Altecs like the 820 (and VOTT) which IMHO is in the running for the best speaker ever made.

Edited November 2, 2015 by Bubo

[Coytee]

Keep in mind I will be listening near field and not at concert levels.

 

When I had my 3-way Khorns, (with extreme slope crossovers), I discovered by accident that their sound congealed into a 'single voice' around 30 feet away.  I actually measured the distance.  When I swapped them out for the 2-way signal aligned Jubilee, which sounded even more grand than the Khorn, I soon went to that 30 foot spot to hear how much better they were going to sound.  I was a bit surprised when they didn't sound distinctly better at 30' like the Khorn did.  What I later discovered was, by losing a crossover point, the sound of the 2-way speaker coalesced into this "one voice" around 10' away from the speaker.  This meant that I could get better sound while being IN the same room as the speakers. 

 

I would expect that taking the LaScala from a 3-way to a 2-way would have a similar effect.  This might dovetail with exactly what you are trying to do in spite of some saying that the 2 inch horn is "long throw" or for PA use.  Look them up, you won't find too many negative comments about them. (K510/K402)

 

Coyote, should be here any minute to recommend the K-510 and K-402.

 

Dave

 

Getting in after Chris, but I'm glad I beat Coyote to the punch! He's a slippery dude!!

 

I recommend either of the two JubScala configurations. There's no comparison using either horn in a two-way with a good 2" compression driver-they will eclipse the stock La Scala 3-way configuration.  You'll need EQ for either controlled directivity horn (K-402 or K-510).

 

Chris

 

 

^^ This ^^  He's the musician in his family and an engineer (we all know how OCD they are!) 

[moray james]

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical

 

I would not have thought that the baffle would make that big of a difference. With a hand on the outer flare of the horn during offending passages there is little to no vibration and no movement, however it would not be difficult to route a few panels to experiment with this.

 

 

Greetings. In July I set out to build a pair of DIY La Scalas that utilized several upgrades detailed on the forum right from the get go.

 

Welcome to the forums, your work on the bass bin is exceptional, keep it up.

 

Dave

Thank you very much!

 

 

 

Very cool!

 

Thank you!

 

 

while you are considering your options you might investigate experimenting with a Karlson K-Tube. I uses a double cutaway looks rather like a Bishop's cap. You can make a paper one for a cent piece of paper and some tape. I know that I won't be switching back to horns again. All that is required is to rol a paper tube with an O.D. the same as your driver exit opening I.D. a thin wire like the wire in a twist tie to make a hoop to keep the tube in a round shape after you make the necessary cutouts.. I set mine up parallel to th eflpoor at my seated ear level looking straight down each tube solid uncut sections of the K-Tube are in the horizontal plane. .I do plan to experiment with 25 PPI open cell foam plug for my tubes but they sound so good as simple paper tubes I have so little incentive to change what is working so well. What have you got to lose? Best regards Moray James.

I forgot about these. Im sure I have more than enough of the materials laying around to construct these. Is there any formula or rule of thumb to follow to successfully build these?

There are formulas for the cutout profiles but I have not used them in years and I like profiles that result in the flare opening faster toward the mouth so I just draw them on with a felt tip pen by eye. seems to work. when I find a profile that I really like I may get help from a geometry savvy friend and draw up and accurate version but my by hand and eye versions are more than enough to keep me happy. Takes a minute or two to make a tube with a piece of scrap paper.

Attached is a good photo (not mine) showing on the right a single cutaway K-Tube and to the left a double cutaway K-Tube both made from thin wall plastic pipe. I honestly believe that paper is a better choice as it will store so much less energy and the plastic will want to resonate, I imagine that could be dealt with but the paper is simple and it is so low in energy storage. Make the K-Tube so it is super thin (1-2 layers)so it can slip into (snugly)the compression drivers mouth or if you decide to make the paper tube thick make the K-Tube ID the same as the compression drivers mouth ID and line them up closely so there are no discontinuances between the CD and the K-Tube openings. I hope that this is of some assistance.

Edited November 2, 2015 by moray james

[No.4]

Wow. There is a ton of great information here guys! thanks. I will try a few of these suggestions tonight and try to route some baffles this week. Moray I have some research to do on the karlson thanks to the links Bubo posted. That should keep me busy tonight.

 

 

 

I would first try a baffle for the current two horns and also have the tweeter with the long dimenton vertical

 

I would not have thought that the baffle would make that big of a difference. With a hand on the outer flare of the horn during offending passages there is little to no vibration and no movement, however it would not be difficult to route a few panels to experiment with this.

 

Look at the bottom of page 3: https://community.klipsch.com/index.php?app=core&module=attach&section=attach&attach_id=8074

 

Also, try moving the K-77 tweeter back to the K-55 midrange compression driver plane and listen again: the soundstage should expand rather dramatically.

 

I will try this tonight!

 

Coyote, should be here any minute to recommend the K-510 [or] K-402.

 

I recommend either of the two JubScala configurations. There's no comparison using either horn in a two-way with a good 2" compression driver-they will eclipse the stock La Scala 3-way configuration.  You'll need EQ for either controlled directivity horn (K-402 or K-510).

 

Chris

 

This sounds great but is outside of the budget right now.

 

 

The K401 will sound pretty smooth on axis with the atlas driver. You may just try attenuating the mids about 3db and listen some more.

For sure, Chris' note to move the tweeter back to be in line with the mid driver will also help tremendously.

Bruce

 

I will have to check with Bob to see if I can move taps on the a/4500s, I think the taps are soldered. If Bob says its OK I will de solder and add some fastons and give it a shot.

 

 

 

Thanks again to everyone who has contributed to this thread!

Edited November 2, 2015 by No.4

[Chris A]

The La Scala and Belle bass bins are about 36 inches (EDITED) path length from compression slot to the front face of the cabinet, effectively. 

 

Also note that any passive or active crossover will insert from 90-360 degrees of phase lag of the lower frequency driver relative to the higher frequency driver (90 degrees per "order" of the filter used: for a fourth order filter, that's 360 degrees lag of the LF driver relative to the HF driver). 

 

My working rule of thumb is that the time alignment needs to be within 1/10th of a wavelength (i.e., 36 degrees) of perfectly aligned at the center crossover frequency.  For 400 Hz crossover (bass bin to midrange), that's about 3.4 inches maximum misalignment--including crossover phase shift error.  For the tweeter-midrange crossover, nominally at 5 kHz, that's about a quarter of an inch, max misalignment, including crossover filter phase shifts.

 

Chris

Edited November 2, 2015 by Chris A

[moray james]

Thanks Bubo for finding and posting all those links, Freddy Ireson would be proud of you. I expect if Freddy felt better these days he would have beat you to posting those. More is always better than less. Best regards Moray James.

[Chris A]

Note that my Belle tri-amp settings used 979 microseconds (equivalent to about 13.3 inches at room temperature) delay on the midrange relative to the woofer,. (I was using a 4th order Linkwitz-Riley digital crossover.)  The La Scala has a longer midrange horn (400 Hz crossover instead of 500 Hz for the Belle).  That means that the midrange delay for a La Scala using its longer midrange horn is about 783 microseconds, or equivalent to about 10.6 inches set back front the face of the bass bin.

 

Both these cases assume that you're using a L-R 4th order.

 

Chris

Edited November 2, 2015 by Chris A

[Bubo]

Thanks Bubo for finding and posting all those links, Freddy Ireson would be proud of you. I expect if Freddy felt better these days he would have beat you to posting those. More is always better than less. Best regards Moray James.

 

When you mentioned a new type of wave guide/horn, it was like the meat truck passing a hungry dog.......I had to chase it......

[Bubo]

What is the efficiency of the LaScala Bass Section (for that matter what is it's Ohm spec).

 

2-Way Crossover 500 Hz, 8 Ohm

 

Woofer 8ohm + 8 ohm Compression Driver and L-pad connected to Crossover = 8ohm speaker

 

If I recall correctly, Eminence sells a very affordable 2 way Crossover and the L-Pad attenuator.

 

 

2) With the LaScala bass bin, as we experiment with horns, can we move the crossover point up to 500 or even 800 without noticeable degradation of the Bass performance and can the woofer handle the added frequencies gracefully aka the voice still sounds like a voice.

 

Nov-3

Updated above after a tutorial on Crossovers.

 

http://www.parts-express.com/eminence-pxb2-500-2-way-speaker-crossover-board-500-hz--290-630

 

http://www.parts-express.com/pedocs/specs/px-series-crossover-specification-sheet-specifications-44571.pdf

 

http://www.parts-express.com/eminence-px-lpad-crossover-l-pad-attenuator--290-660

Edited November 3, 2015 by Bubo