Jump to content
The Klipsch Audio Community
Roby Italy

Upgrade La Scala

Recommended Posts

2 minutes ago, polizzio said:

 

So how does my sealed cab direct radiator SVS SB-3000 sub generate a 25 hz signal?  It has no horn.

 

Just like any other direct radiating subwoofer.

 

Sealed subwoofers for home audio commonly use DSP to boost low frequencies.

Share this post


Link to post
Share on other sites
3 minutes ago, Chris A said:

I think that the acoustic phenomenon that is being searched for here is "transformer".  Horns are acoustic transformers.  They also give directivity gain, like was pointed out above, but the major effect is the transformer effect due to the horn.  Here is an excerpt from Bruce Edgar's trip to Hope to interview PWK for Speaker Builder Magazine in 1989 that shows you the difference between a direct radiating woofer and the same woofer being used behind a proper horn:  https://community.klipsch.com/applications/core/interface/file/attachment.php?id=96455

 

 

 

I agree with directivity gain vs a DR, a focused beam like output. I mentioned that above several posts above. A horn cab precisely focuses the acoustic energy from the transducer.

 

Chris do you believe the actual acoustic output from the transducer is "amplified" in a horn cab? A passive amplifier as Carl stated.

Share this post


Link to post
Share on other sites

The reason why the Cornwall bass bin doesn't sound as clean as the La Scala bass bin is due to the horn loading acoustic transformer effect that makes it possible for the 15" woofer in the La Scala only has to move 1/5th the distance as the same 15" woofer in the Cornwall in order to achieve the same SPL on axis.  This dramatic reduction in required movement results in much, much lower modulation distortion sidebands in the La Scala bass bin than the Cornwall--but this is only audible at higher SPL.  The harmonic distortion levels are the same at higher SPL,but the horn-loaded bass bin will have inaudible levels of modulation distortion sidebands--the "mud factor" that PWK wrote about.

 

 

 

 

 

  • Thanks 1

Share this post


Link to post
Share on other sites
18 minutes ago, jason str said:

Sealed subwoofers for home audio commonly use DSP to boost low frequencies.

 

Absolutely agree with you on the DSP compensation/boost. Enhanced/boosted very low frequency output.

Share this post


Link to post
Share on other sites
7 minutes ago, polizzio said:

 

I agree with directivity gain vs a DR, a focused beam like output. I mentioned that above several posts above. A horn cab precisely focuses the acoustic energy from the transducer.

 

Chris do you believe the actual acoustic output from the transducer is "amplified" in a horn cab? A passive amplifier as Carl stated.

TRANSFORMER...not directivity gain...is the major effect.  The directivity effect yields much lower SPL gain on-axis than the transformer action.  Woofers have a lot more resistance to push against at the mouth of a horn than if direct radiating, especially if designed using a "compression" effect (a reduction in the output area of the horn throat relative to the woofer diaphragm area).

 

Chris

Share this post


Link to post
Share on other sites
10 minutes ago, Chris A said:

TRANSFORMER...not directivity gain is the major effect.  The directivity effect yields much lower SPL gain on-axis than the transformer action.  Woofers have a lot more resistance to push against at the mouth of a horn than if direct radiating.

 

Chris

 

Chris, define "acoustic transformer" in your words for me, please. The paper you linked gave none, i read it. How does an acoustic transformer work?

How does it amplify acoustic energy from a transducer? How does it produce a measurable gain?

 

"Woofers have a lot more resistance to push against at the mouth of a horn than if direct radiating."

Are you stating there is a form of compression @ the mouth of the horn?

More resistance to cone excursion than a sealed cab direct radiating?

 

Share this post


Link to post
Share on other sites

Let's just call the LS.bass bin a horn. Or folded horn.

Share this post


Link to post
Share on other sites
1 hour ago, polizzio said:

 

Quindi il tuo dire se la cabina del corno basso fosse molto più grande, altererebbe la risposta in frequenza del trasduttore?

 

Devi spiegarmelo.

I, on the other hand, would like someone to explain to me how horn-loaded subwoofers with smaller cabinets than the LS cabinets go so low ... yet they do

Share this post


Link to post
Share on other sites
1 minute ago, billybob said:

Let's just call the LS.bass been a horn. Or folded horn.

 

ah......we all agree on that.

 

My Peavey SP-1s 40 years ago were of the same design. Folded horn LF cab.

Share this post


Link to post
Share on other sites
8 minutes ago, polizzio said:

Chris, define "acoustic transformer" in your words for me, please.

I really don't have to use my words.  A quote:

 

Quote

The horn can be thought of as an "acoustic transformer" that provides impedance matching between the relatively dense diaphragm material and the less-dense air. The result is greater acoustic output power from a given driver.[1]

 

https://en.wikipedia.org/wiki/Horn_loudspeaker

 

The woofer can push against the air at the throat of a horn many times more efficiently than in direct radiator mode.

 

Chris

Share this post


Link to post
Share on other sites

For sake of conversation...or even horn loaded for the sake of those who may not be as conversant with the terms...

Share this post


Link to post
Share on other sites

--

 

Share this post


Link to post
Share on other sites
8 minutes ago, polizzio said:

You didn't answer my question I posed to you above.

I believe that transformers and amplifiers can be thought of in similar fashion.  An electrical transformer transforms electrical voltage (potential) for current via a magnetic circuit (by a difference of the number of wire turns on a iron core circuit). 

 

An electrical amplifier controls the output voltage/current via a "valve" or transistor.  The effect is the same at the source: trading current for potential (voltage in the case of electricity), and in the reverse (vice versa). 

 

To me, it's only a matter of semantics.  One concept may work better than the other at some level of aggregation.

 

Chris

Share this post


Link to post
Share on other sites
1 hour ago, Roby Italy said:

I, on the other hand, would like someone to explain to me how horn-loaded subwoofers with smaller cabinets than the LS cabinets go so low ... yet they do

 

The La Scala bass bin is a short horn, subs are a different design.

 

At the expense of output.

 

Small driver, small horn = low output.

Share this post


Link to post
Share on other sites

@Chris A

 

Throat is where compression would occur. Mouth is outlet. The wiki on horn loudspeaker has helped me. 

  • Like 1

Share this post


Link to post
Share on other sites
5 minutes ago, jason str said:

Small driver, small horn = low output.

I think the deeper issue is what is called "Hofman's Iron Law": having to do with trading three different parameters--in this case efficiency.

 

Quote

Hofmann argued that the designer had "...three parameters that cannot all be had at the same time": good, deep low-frequency sound, a small cabinet size, and high sensitivity. Hofmann stated that designers could pick two of these three parameters, but in doing so, it would compromise the third parameter.[4] For example, a designer who wants good, deep low-frequency sound and high sensitivity can obtain these goals, but they will have to use a large speaker enclosure. Similarly, if a designer is forced by space constraints to use a very small cabinet, and they aim to get good, deep low-frequency sound, the sensitivity will be compromised. A small cabinet with deep bass would need a very powerful amplifier.

 

https://en.wikipedia.org/wiki/Josef_Anton_Hofmann

 

Also note that the effects of higher distortion (modulation, compression, etc.) become much more pronounced with lower efficiency loudspeakers.

Share this post


Link to post
Share on other sites

A good video to visualize transformer action, starting at minute 19:

 

 

Share this post


Link to post
Share on other sites

Yes, very interesting. Just for observation, did not hear the terms, undulation or waveform.

Although they were certainly implied.

Share this post


Link to post
Share on other sites
1 hour ago, Roby Italy said:

I, on the other hand, would like someone to explain to me how horn-loaded subwoofers with smaller cabinets than the LS cabinets go so low ... yet they do

where? please links,please.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...