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Is Klipsch breaking PWK’s rule #5?


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The La Scala AL5 comes with risers that look to raise the speaker about 3” off the floor. The risers can be seen at about the 7:00 mark of this video:

 

Having the riser seems to contravene rule #5 of PWK’s "8 Cardinal Points of Reproduction" (aka PWK’s 8 Rules😞

     5. Freedom from cavities. The space under a speaker box formed by mounting it on legs

    can destroy the bottom octave of response and deteriorate the next two octaves.

 

Did Klipsch find that risers don’t affect sound like legs so that risers are OK?

 

I’ve been thinking about adding risers to my ’86 La Scalas to get them 3" to 6" off the floor (to avoid damage and also to raise the tweeters closer to ear height) but wanted to know the pros and cons before building them.

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To me, PWK’s rule referred to creating an open space under the speaker, not a closed riser.  For one example, the La Scala II has a riser under it, unlike the original La Scala, which sits right on the floor.  However, the LS2 has stronger bass than the OG model.  Some reports say the bass response even seems to go deeper.  It doesn’t, but that gives you an idea how the riser does not impair the bass response.

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My guess is that a riser that has all 4 of its sides flush with the edges of the La Scala would be O.K., with no true cavties.  The height of the risers should be kept to the minimum that fulfills the purpose of the risers.  Your 3" height should be O.K., I'd think.   The diagrams of reflection of the  Klipschorn on the floor seem to imply that it  needs to have the boundary gain of floor reflections (but they are not  desirable in the midrange and treble, thus Heyser's recommendation of a thick rug and rug pad).  Obviously, we wouldn't expect a riser 8 feet tall to be good (with  a ceiling far, far away), because the floor would be too far away to reinforce bass.  So, within limits.

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3 hours ago, Dave MacKay said:

The La Scala AL5 comes with risers that look to raise the speaker about 3” off the floor. The risers can be seen at about the 7:00 mark of this video:

Having the riser seems to contravene rule #5 of PWK’s "8 Cardinal Points of Reproduction" (aka PWK’s 8 Rules

No worries at all  Heresy , Cornwall  speakers use risers since 1957 /1959 ,  Forte , Chorus speakers are  equipped with risers 

 

PWK's  Cardinal rule no 5 was used in the sound industry  since the 40's in all types of venues , with closed-sealed  platforms installed under commercial speakers 

 

The perfect example  is the 1942  Serial no 1  , the 1st Prototype of the  Khorn  .

 

 

(Foto: Producent)

 

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When sitting on carpet, the LS2, with its open bottom, comes closer to being coupled to the floor than the older flat-bottomed La Scala, which kind of ”floats” on the carpet.  That said, the older model is easy to reposition, while the LS2 practically needs to be lifted to be moved on carpet, otherwise there’s a chance of damaging the riser.  I’m considering getting thick plastic sheets (1/4”-1/2” thick) to screw to the bottoms of the 200-pound (including the 402 horn/driver/base assemblies) La Scala IIs, in order to make moving them a simple single-person operation.

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5 minutes ago, Islander said:

the LS2, with its open bottom, comes closer to being coupled to the floor than the older flat-bottomed La Scala, which kind of ”floats” on the carpet.

How exactly do you figure that?

 

Plastic sheets?  For real?  How about these, they work very well.

 

https://www.amazon.com/dp/B07WDX5LC8?psc=1&ref=ppx_yo2ov_dt_b_product_details

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5 hours ago, jimjimbo said:

How exactly do you figure that?

 

Plastic sheets?  For real?  How about these, they work very well.

 

https://www.amazon.com/dp/B07WDX5LC8?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

On the plush carpet in my place, the 1st-gen La Scalas were easy to slide around on the carpet.  I was able to move them from the front of the room to behind the sofa with minimal effort, by myself.  That's what I meant when I said they practically float on the carpet.

 

With the La Scala IIs, on the other hand, just to turn them a bit to reduce their toe-in required a helper to lift off the big tweeters, then to lift off the HF cabinets, then the bass cabinets were pretty easy to move, since they're fairly light.  Then we put the HF cabinets back on, followed by the tweeters.  The only simple part of the job was that no wiring needed to be disconnected and reconnected.  That was because the HF cabinets aren't in use, so they're not connected to anything, and the wires to the tweeters are extra long, so the tweeters can be moved a bit while they stay connected.

 

The previous owner removed the original feet and apparently lost them.  Instead, he fitted small white rubber feet to them, to protect his hard floor.  After I'd had the speakers for a while and found them impossible to move by myself, I thought that these little feet were the problem, so while we had the bass cabinets by themselves, we turned them over and unscrewed those little feet.  Unfortunately, that did not make the fully-assembled speakers any easier to move, because now the risers sank right into the carpet.  That was frustrating.

 

Those furniture glides in the link (thanks for the link) would work great on a hard floor, but I don't think they'd make much difference on the carpet.  Those LS2s are really heavy.  The reasoning behind attaching slippery plastic sheets/slabs/plates under them would be to allow them to be skidded around as easily as the old La Scalas.  I haven't done it yet, though.

 

Well, that exercise of reducing their toe-in didn't widen the sweet spot at all, and the speakers were just as immovable without their feet, because the risers sink right into the carpet.  We later had a disagreement about something, so I don't plan to ask that relative to come back anytime soon.  Luckily, the tweeters are easy to rotate, since the speakers are in effect splits.  I turned the tweeters inwards as recommended by PWK in 1951, with each speaker aimed at the opposite corner of the room, and now I have the wider sweet spot that I was looking for.  However, having the big tweeters turned so far inwards relative to the rest of the speakers looks odd at best.

 

At this point, I'm looking for the Final Solution that will enable me to move the speakers whenever I like, to experiment with their positioning whenever and however I like.  This is why the apparently odd idea of installing a hard but slippery plastic base is sounding good.  The material isn't expensive, and my young nephew should be willing to help with no grumbling.

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10 hours ago, OO1 said:

No worries at all  Heresy , Cornwall  speakers use risers since 1957 /1959 ,  Forte , Chorus speakers are  equipped with risers 

 

PWK's  Cardinal rule no 5 was used in the sound industry  since the 40's in all types of venues , with closed-sealed  platforms installed under commercial speakers 

 

The perfect example  is the 1942  Serial no 1  , the 1st Prototype of the  Khorn  .

 

 

(Foto: Producent)

 

 

Thanks for that picture, Randy.  It’s very interesting to see the original, elemental, Klipschorn.

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3 hours ago, mustang_flht said:

Hi @Dave McKay

 

The risers under my Cornwall III are 2" high and they are recessed 1.18" from the edges of the body.

 

Someone should measure La Scala II or AL5 risers for you 😉

 

Okay, Dave, here you are.  

 

The risers under La Scala IIs are 2”/5.1 cm tall.  

 

The side inset is 15/32”/1.2 cm.

 

The inset from the fronts of the speakers is 15/16”/2.35 cm.

 

As for experimenting with various heights, if you have some old phone books, or any kind of large books, you could experiment with them.  Within a few months of getting my original La Scalas, I read here on the Forum about how the sound could be improved by tipping them back a bit.  All that took was a 2”x4” under the front of each speaker, which gave a 2-inch lift.  Turning them the other way, to get a 4-inch lift, looked a bit wobbly and extreme, so I immediately put the plank (“plank” sounds odd for a short 2-foot length, but I guess that’s the right word) back to the more stable 2” rise position.  Spoiler:  it did not improve the sound at all.  It gave it a sort of nasty irritating quality to the sound, which caused me to return the speakers to level the next day.

 

Have you got some 2-4s?  That would give you about an 8-inch/20 cm. lift, if you have 8 available (4 per speaker.  Safety first!).

 

For the actual construction of the risers, the consensus seems to be that a sturdy closed box is the best/only way to go.  3/4”?  1”?  Thicker is probably better, but PWK would probably say that considering the extra cost, “It wouldn’t make a dime’s worth of difference.”  That means a closed bottom, which, as I’ve posted elsewhere, would retain your Scalas’ easy movability on carpet.  If you have the steel button feet, if they’re easy to remove, you could reinstall them on the bottoms of the riser boxes., or even order a set of 8 La Scala II feet.

 

Another consideration is the protection of your speakers.  In my experience, the biggest threat to the finish on La Scalas and other speakers is the vacuum cleaner.  You can tell your vacuum operator that the inch of carpet in front of each speaker does not need to be vacuumed!   No matter what you say, if you’re lucky you may hear an “Oops!”, but more likely you’ll be looking around later, notice the new blemish on your mint speaker, and if you’re very lucky, you may spot the bit of veneer that got chipped off and try to figure out how to reinstall it with no visible damage.  Good luck with that!

 

That last paragraph is a long-winded recommendation that you measure the height of that implement of destruction, and then make your riser a bit taller than that.  This will cut down on the swearing and gnashing of teeth in your room.  Thank me later.

 

Okay, this is getting way too detailed, and I don’t want to make all of your decisions for you.  That would be rude.  Sorry about that.  Anyway, happy experimenting and happy listening!

 

Final note:  the best riser, although it may be a bit tall, is the KP-480 subwoofer.  A pair of those would make your La Scalas the complete package, lol!. 

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  • 2 weeks later...

My vintage La Scalas are in my small carpeted living room. They have a number of mods, but they sound better with 2 inch planks in the front, plus big round rubber washing machine feet under the planks. It works for very low level listening with tube amps. Not doing much loud listening in my apartment.

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21 hours ago, pcbiz said:

My vintage La Scalas are in my small carpeted living room. Not doing much loud listening in my apartment.

 

My home is an apartment also (in a steel and concrete building), so to be a good neighbour, I keep the time in mind when setting the volume.  The lowest volume I use (60-70 dB) is after 11 pm, and for music, rather than TV, I often leave the subwoofers off.  For evenings, the volume goes higher (65-80 dB), and when I want to listen at fairly high volume, where the speakers really wake up and every detail in the music becomes clearly audible (70-95 dB), the best time is in the afternoons (noon-5:30 pm), when most or all of my neighbours are likely to be at work.  Since I’m retired, that’s no problem.

 

It has worked out well so far, with no noise complaints ever.  As for noise coming into my apartment, when one of my downstairs neighbours has a party, a few times a year, I can hear murmurs of crowd conversation below my living room, but not loud enough to grumble about, plus they usually shut things down before my bedtime.  It’s worked out great for nearly 20 years, so I’m pretty happy.  About the only limitation, a self-imposed one, is that I don’t get to play the system at “show-off volume” for visitors in the evening.  I can live with that.

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30 minutes ago, Islander said:

 

It has worked out well so far, with no noise complaints ever.  

if you can blast away at  80-95 dB   You  have very  cool ,  super  music loving neighbors     , or  you're living with seniors who  are 1/2 deaf  , with hearing aids  ,  

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6 hours ago, OO1 said:

if you can blast away at  80-95 dB   You  have very  cool ,  super  music loving neighbors     , or  you're living with seniors who  are 1/2 deaf  , with hearing aids  ,  

 

Well, I just do that in mid-afternoon, when they’re mostly at work, and not every day.  Sometimes I only listen loudly to one or two songs.  It’s pretty much mandatory to turn it up when Pink Floyd comes on, right?

 

Talking about nearly deaf neighbours, years ago I learned that a doom rock band called Mitochondrion lived one floor down, on the other side of the building.  The only grumble we ever heard was from the little old lady who lived directly below them.  She thought there might be something wrong with the pipes, since she could hear some odd banging.

 

As a member of the Strata Council, sometimes I would accompany the alarm inspector when he came to verify the operation of all the smoke and heat alarms (we have both, a few feet apart).  In that role, I got to see every apartment in the building.  In the apartment occupied by the band member, there was a full drum set in the living room and a baby grand piano in the dining room.  Somehow, only that one lady had even a mild complaint.

 

What does it take to get a complaint?  Well, we have a hard-drinking guy who brings friends and strangers home and BLASTS his stereo.  No 11 pm shutdown, either.  At 4:30 on a Tuesday morning, the neighbours from the floors above and below him were yelling at him and throwing things onto his balcony, in an effort to at least get his attention.  The cops came that time, and a few other times, too.  He eventually got a clue, and hasn’t done that in a long time.  Even so, I didn’t hear a thing in my place, since my bedroom’s on the other side of the building from his living room, and I live several floors above his place.

 

Most of the noise complaints in our building are due to footfalls, mostly in apartments that had their original carpeting replaced with hardwood flooring.  It’s the trendy thing to do, but you have to get the approval of the Council, and you have to install sound absorbing underfloor that meets a certain spec.  Even so, some people have heavy enough feet or shoes to annoy or drive crazy their downstairs neighbours, depending on both people involved.  My carpet is still intact, and our windows were upgraded when our building had a major overhaul a decade ago.  Those windows really lowered the noise floor in my place, which pleases me every day.  Traffic noise is pretty much eliminated, which is great.

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5 hours ago, Islander said:

 

My home is an apartment also (in a steel and concrete building), so to be a good neighbour, I keep the time in mind when setting the volume.  The lowest volume I use (60-70 dB) is after 11 pm, and for music, rather than TV, I often leave the subwoofers off.  For evenings, the volume goes higher (65-80 dB), and when I want to listen at fairly high volume, where the speakers really wake up and every detail in the music becomes clearly audible (70-95 dB), the best time is in the afternoons (noon-5:30 pm), when most or all of my neighbours are likely to be at work.  Since I’m retired, that’s no problem.

 

It has worked out well so far, with no noise complaints ever.  As for noise coming into my apartment, when one of my downstairs neighbours has a party, a few times a year, I can hear murmurs of crowd conversation below my living room, but not loud enough to grumble about, plus they usually shut things down before my bedtime.  It’s worked out great for nearly 20 years, so I’m pretty happy.  About the only limitation, a self-imposed one, is that I don’t get to play the system at “show-off volume” for visitors in the evening.  I can live with that.

 

Nice neighbors are great. I play guitar, sometimes a little louder than I think. The only complaint was from the couple across from me. "You didn't tell us where your last gig was. That would have been our date night."

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OK, so the issue is coupling the speaker to the floor. 

 

I have stands for my Chorus and Fortes that have feet, but with rubber bottoms that really grab the floor.  This seems like a better grip than the original metal skids that allow the speaker to easily glide across the floor.  I was also going to drill holed through the stands and mount the stands to the speakers in the original holes, but I put carpet nonslip pads between the stand and the bottom of the speaker and these things will not budge if you try to push or twist them on the bottoms. 

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