La Scala Bass Reflex Mod

[ClaudeJ1]

On 11/30/2018 at 12:10 PM, zobsky said:

So here is my opinion of the bass reflex mod.

 

It does work to extend the response lower - but just not enough (even with boost) - for my taste i.e. it does not eliminate the need for a subwoofer. I've tried it with a crites cast frame woofer and eminence kappa 15 .

 

That said, it might have value in extending the response just a bit lower to make integration with a subwoofer easier.

 

A laclala /belle + subwoofer is so much much better than one might expect.

 

A bass reflex mod is NOT a compromise I could live with. A Kappa 15 C will give superior midrange/midbass definition, and even a cheap Subwoofer from Parts Express (15") is better than the bass reflex mod. But yeah, like most people, somone will WASTE time and money on this crappy "almost" mod regardless of what we tell them. I actually prefer a LaScala or Belle with sub over a Klipschorn any day of the week because of greater phase coherence between the bass and the squawker horns.

[ClaudeJ1]

On 12/3/2018 at 12:33 AM, Islander said:

 

When the amplifier in my sub had to go to the manufacturer to be serviced, I listened to the La Scalas without the sub for a couple of weeks, and really missed the sub.  Even for acoustic folk, the sub added depth and authority to the sound.  Some audio purists at magazines like The Absolute Sound thought subs were just for explosions in movies in home theatre systems, but when they checked out properly set up subs with their high end systems, they found that the subs had effects all the way into the midrange, and also gave a much better sense of the size and shape of the performance space, with recordings that were made with all the musicians in the same room at the same time, of course.

 

During the time the main 500-watt subwoofer was away, I hooked up one of the 90-watt bedroom subs, and for acoustic folk or jazz, it was adequate, but for rock or for movies, the bigger sub was needed.

 

As for accuracy and balance, it took quite a few test runs with a set-up CD and an SPL meter, from 200 Hz. down to 20 Hz., with the signal to the sub going through a 10-band equalizer, to get as smooth a response as possible, with the worst peaks and dips tamed a bit, before I was satisfied with the sound.  It was time well spent.  The measurements showed that the La Scalas start to roll off as high as 100 Hz., and by 50 Hz., not much is coming out of them.  With the Paradigm sub that I use, the bass response is clean and even down to 25 Hz., which is deep enough for most musical instruments.  For example, a 4-string bass guitar goes down to 40 Hz., while a 5-string bass stops at 30 Hz.

 

Many subwoofers may be claimed to put out useful power down past 20 Hz., but testing often shows that to be very optimistic at best.

 

Also, it doesn't make sense to me to have one setting for music and another one for movies.  Sound is sound, so if the system is dialed in to produce accurate sound, it should do a good job with any source material that's sent through it.  Music will sound as the artist and engineer wanted it to sound, and movies will have as much bass as the director intended, with no need to bump it up for "extra slam". 

 

So that's my opinion, backed by testing in my own listening/living room.  Your results may differ, of course.

I agree with your opinion. As a man who spent time and money over the last 13 years getting down to the TEENS in the subwoofer department (huge Tapped Horns and Full Horns that get to 20 Hz. and below) I concur with what you say here. For music only, getting to 30 Hz. takes care of 99.99% of music. 20 Hz. and below is for stuff blowing up in movies to get a SHOCK WAVE in your living room, mostly and where the expense is high and returns low, literally and figuratively.

[OO1]

8 hours ago, sootshe said:

Here's the slot loaded picture.

 

Technically any amelioration in the bass bin of the LS would have to come out of the   dog house ,  and not the bass extension cabinet as the main producer of the bass  is  still the dog-house ---

-in an optimal design ,the woofer  would need repositioning and a longer LS bass bin or a wider LS bass bin  would be needed  -

is there real data /curve graph  showing any bass amelioration -with this design   ?    as it looks a lot better than most LS bass extensions thus far -

[ClaudeJ1]

On 8/3/2020 at 11:15 AM, RandyH000 said:

Technically any amelioration in the bass bin of the LS would have to come out of the   dog house ,  and not the bass extension cabinet as the main producer of the bass  is  still the dog-house ---

-in an optimal design ,the woofer  would need repositioning and a longer LS bass bin or a wider LS bass bin  would be needed  -

is there real data /curve graph  showing any bass amelioration -with this design   ?    as it looks a lot better than most LS bass extensions thus far -

Real measurements were posted a long time ago and were a slight improvement, but only about 10% of what even a cheap sub would do. Wrote it off as a waste of time. If you want to cut lumber and get a FULL octave of extra bass, then build my Quarter Pie Horn that's FLAT to a solid 52 Hz (Flatter than LaScala, Belle, or Khorn!). which trounces the anemic HORN PORTION of the LaScala. It's a 5.5 foot horn vs 2.75 ft. horn for the LaScala But totally fills the corner and only sticks out an extra foot into the room. Twice as long  of a horn gets you a full octave with the SAME Driver, wheter it's a K33 or K43. But you would still need a subwoofer to get down to 30 Hz. Also no one talks about the reduction of IM Distortion, which was PWK's main point of bass horns. Porting a LaScala increases the IM distortion because the cone moves more than keeping it as a full horn only. Not a good trade-off.

[ClaudeJ1]

6 hours ago, RandyH000 said:

Technically any amelioration in the bass bin of the LS would have to come out of the   dog house ,  and not the bass extension cabinet as the main producer of the bass  is  still the dog-house ---

-in an optimal design ,the woofer  would need repositioning and a longer LS bass bin or a wider LS bass bin  would be needed  -

is there real data /curve graph  showing any bass amelioration -with this design   ?    as it looks a lot better than most LS bass extensions thus far -

Another waste of good lumber.

 

[OO1]

5 minutes ago, ClaudeJ1 said:

Another waste of good lumber.

 

a good sub right

[OO1]

4 hours ago, ClaudeJ1 said:

Also no one talks about the reduction of IM Distortion, which was PWK's main point of bass horns. Porting a LaScala increases the IM distortion because the cone moves more than keeping it as a full horn only. Not a good trade-off.

no , for sure  , the door is removed

[ClaudeJ1]

3 hours ago, RandyH000 said:

a good sub right

All speakers, even Khorns need a sub. The only reason a Jubilee can get by without one is you can put in a 7 db PEQ boost with you Digital Crossover at 32 Hz. With Twin 12" drivers being the equal of an 18", it doesn't increase distortion when you do it because there is so much cone AREA to work with.

[Bacek]

10 hours ago, ClaudeJ1 said:

Another waste of good lumber.

 

 

Thanks for your feedback. I'm aware of all cons and pros for bass reflex mod. So let me decide for what I'll waste my money and time.

Probably I'll end with sub anyway but just want to check it by myself.

And definitely on this mod I'll waste much less  good lumber then on Quater Pie's

[garyeanderson]

   Money, Time, and Space. Time goes by, money can be replaced, space is expensive. FH-1's are still inexpensive and with $15 worth of Baltic birch (craigslist) and some wasted time I ported them.  This is a cheap hobby for me and I enjoy the hands on approach. All of this said, I play the Belle's most of the time along with the MWM bass bin in mono (the black Khorn top is not connected}. For a change of pace, I have the H700's now sitting on top of the FH-1's, its a settle difference. Remember, Just have fun, that's what life is for. 

 

 

[garyeanderson]

20 hours ago, Bacek said:

This exactly one I was thinking about.

Basically I will reproduce those 4 inch diameter 7 inch length ports with rectangular one. Only problem could be that on front exit of a doghouse is trapezoidal so it will work like lightly larger/flared entry duct..

 

  I think that Dave opened the doghouse to the top and used sealed off the back of the top and used that space for the extra volume. He then  removed the bottom hatch and built it with the port facing  the front.

[Bacek]

Yes, exactly this is how it will be done.

[Bacek]

1 hour ago, garyeanderson said:

Money, Time, and Space. Time goes by, money can be replaced, space is expensive. ...  Remember, Just have fun, that's what life is for. 

 

If I had as much space as you I would start Jubilee build (it's still on queue, drivers are waiting but I'm waiting for that space ).

And definitely all those are fun projects for me. And I intend to keep it that way.

 

Unfortunately time flies when you're having fun so this is kind of vicious cycle.

[ClaudeJ1]

3 hours ago, Bacek said:

If I had as much space as you I would start Jubilee build (it's still on queue, drivers are waiting but I'm waiting for that space ).

And definitely all those are fun projects for me. And I intend to keep it that way.

 

Unfortunately time flies when you're having fun so this is kind of vicious cycle.

Now THAT would NOT be a waste of good lumber, and would use less floor space than either a LaScala (ported or not), MWM, or Quarter Pie. IOW, it would be a great use of lumber, and with the inherent requirement of modern ACTIVE crossover, would get you the very best musical performance, WITHOUT a SUB!! Yes, I owned a pair and the 32 Hz. PEQ recommended by Roy Delgado really works. You will feel bass in your calf muscles!!

[DizRotus]

I agree with Claude.  Using a sub, or subs, is preferable to the bass bin mod.

 

Fortunately, I had a unique opportunity to implement the mod on a pair of La Scalas used in a high school band practice room.  There was absolutely no way a sub would be incorporated, neither was it really needed.  The minimal gain provided by the bass bin mod was worth the effort in that unusual situation.  Using the space in the top hat did not “waste good lumber.”  The ported door used to close the top hat was scrap.

 

Use subs whenever possible.

 

 

[Islander]

On 8/3/2020 at 8:11 AM, ClaudeJ1 said:

I agree with your opinion. As a man who spent time and money over the last 13 years getting down to the TEENS in the subwoofer department (huge Tapped Horns and Full Horns that get to 20 Hz. and below) I concur with what you say here. For music only, getting to 30 Hz. takes care of 99.99% of music. 20 Hz. and below is for stuff blowing up in movies to get a SHOCK WAVE in your living room, mostly and where the expense is high and returns low, literally and figuratively.

 

It’s great to see that we agree on something, Claude.  However, that quote is from 2018, and I’ve learned a bit since, especially since I replaced my subwoofer a few months ago.  Before that, I was fairly satisfied with my sub, a 10” 400 watt unit with a claimed lower frequency limit of 23 Hz.  The new one that I got is also a 10” unit, but with 850 watts (both power ratings are RMS) and a claimed lower frequency limit of 18 Hz.  Since my tests showed that the older sub had an actual lower frequency limit of 25 Hz, and since the new one was by the same brand as the first, Paradigm, I’m guessing its LFL is more like 20 Hz.

 

As you know, 5 Hz at higher frequencies is a small enough difference to be within the error factor of the test gear, like the difference between 4,000 and 4,005 Hz.  At the bottom end, though, the area between 20 and 25 Hz is a big difference, enough to be clearly audible.  Between that and the higher amplifier power, the new sub amazes me.  I can barely imagine what your previous subs sounded like.  This one allows me to have a much better listening experience, with the music sounding more real and present.  Most traditional instruments, as we agree, don’t go below 30 Hz, but quite a few electronic instruments do, as is very easy to hear with electronic dance music (EDM) or deep house music.  I don’t listen to that music very often, but when I do, the new sub makes a world of difference.

 

I’m thinking that part of the difference is frequency headroom, as opposed to the power headroom we usually refer to.  Or maybe it should be called “footroom”, since it’s at the bottom end.  What I mean is that if a sub is reproducing sounds that go near its lower limit, it will sound a bit strained, and therefore unrealistic, while the sub that can go lower reproduces the same sounds with ease, allowing the music to sound closer to the real thing, bringing the home listening experience closer to the live listening experience.  Or, to put it another way, for a sub that can go lower, the music is more likely to be in its linear operating range, which makes for more accurate and realistic sound.  I’m convinced enough that I’m planning to buy a second matching sub, to even out the sound field by having a second source, and to reduce distortion by reducing the necessary excursion on each sub.

 

”If it moves, it distorts”, said PWK, thus the advantage of having the second sub:  the required travel of the drivers of both subs will be reduced, which will reduce the distortion coming from them.  It’s tempting to think that the distortion will be cut in half, but things aren’t always as simple as that.  However, there will be a clear improvement, as long as the second sub’s location is close to ideal.  It also helps that these subs have Anthem Room Correction (ARC), which corrects for room-caused peaks and dips in the below 200 Hz region.

 

It’s very interesting to see the curve measured from 5 microphone locations, then the correction curve which will be applied to it, and finally the corrected curve.  I was surprised at how easy it was to hear the difference once the correction curve was applied, and it was a more pleasant sound.  I’m well pleased.

 

 

[ClaudeJ1]

Yep, we do agree on all this for sure. Although at 20-25 Hz. and below, it all about FEELING the bass, and less about hearing it. Just don't call it a Jube Sub and we'll be fine! LOL.

 

BTW, I really like your term "footroom."

[Full Range]

On the speakers that this bass bin build thread is based on 
The cabinet build is custom DIY 

Built with double thickness sides and back 

The drivers used are not Klipsch 

Drivers used are as follows

Woofers - Crites - CW1526C 15 inch cast alloy 

Mid Range - Great Plains Audio - GPA 399 Compression driver fitted to a pair of Eliptrac 400 timber mid range horns

Tweeters - JBL 2404H Baby Cheeks 

 

The crossovers are custom and based on a few design principles 

Bass specific answers- these are my observations

Depending on the music selection , volume and drive force of the amp 

Thumping feeling in the solar plexus is strong at volume 

Walls vibrate to the touch at all volume levels 

If one puts a piece of paper over the exit port/s it dances with the air pressure  

 

 

[zobsky]

On 8/3/2020 at 1:46 PM, ClaudeJ1 said:

. If you want to cut lumber and get a FULL octave of extra bass, then build my Quarter Pie Horn that's FLAT to a solid 52 Hz (Flatter than LaScala, Belle, or Khorn!). ...

Looks "ugly" though in comparison to LaScala etc ... and we all know that looks are everything

 

Jokes apart, .. I agree with you

1. The bass mod is not an end-all except maybe to integrate to a subwoofer 

2. Adding a horn sub to a la-scala or belle really enhances the overall experience.

[DizRotus]

If using a proper sub, the mod is not needed.