Jump to content

Klipsch heritage speakers to be raised to ear level?


egoquaero

Recommended Posts

5 hours ago, moray james said:
6 hours ago, Heritage_Head said:

Why dose the solid help with bass loss?

easier for the front wave to go around the box to cancel out.

 

What?

 

The low frequency waves are feet long, not inches, and the continuous surfaces aid in their development.  Jumping across open gaps does the opposite.

Link to comment
Share on other sites

8 hours ago, glens said:

 

What?

 

The low frequency waves are feet long, not inches, and the continuous surfaces aid in their development.  Jumping across open gaps does the opposite.

guess I should have said that with the open stand it is a little easier for the front wave of the speaker to get around the cabinet to cancel along with a little less frontal area to help launch the forward wavefront out and away from the cabinet. It didn't come out the way that it had been intended to.

Link to comment
Share on other sites

15 hours ago, Heritage_Head said:

Why does the solid [riser or box] help with bass loss [and the open-leg version does not]?

There are at least two effects that occur when you raise a direct-radiating woofer box (acoustic suspension or bass reflex) away from the floor:

 

* You introduce an additional 1/4 wavelength cancellation frequency ("null") with the floor--which is generally above 200 Hz in the case of direct radiating woofer boxes, and at ~230 Hz in the case of horn-loaded woofers such as the Khorn when it is not sealed properly against the room's corner walls.  This is also referred to as the "Allison Effect" (for reasons that I can't explain, since Klipsch said it well before Roy Allison).  A graphic of that effect even with a flush-mounted loudspeaker on a wall is included below from Toole's book (approximating a solid riser that is discussed in this thread):

 

1077729542_TooleFigure12.9.thumb.JPG.b614511e0035b31d8d03db51971f173b.JPG

 

* You also deny the loading of the woofer cone itself to lower frequencies (the resistive portion of the complex acoustic impedance) due to the loss of room "boundary gain".  This is the major effect in the loss of its deep bass response. It is also a subject of typically great confusion among most audiophiles-especially those that place their loudspeakers away from the walls of the room instead of placing them within 12" of the walls.  Any significant disruption within the first 1/4 wavelength of the frequencies being supported by boundary loading effectively destroys the boundary gain effect, and thus truncates the bass bin's frequency extension, which is seen in the plots that PWK published in the article linked above.

 

You can read more about this subject, where the room boundaries themselves form a straight-sided trihedral horn that extends the bass response of the bass bin via horn loading (called "boundary loading" in this instance in Toole's book). 

 

1138652488_TooleFigure12.1.thumb.JPG.ecd51c12b0f2780f17cf8990cd5b6436.JPG

 

An open-legged riser under a loudspeaker further cancels the boundary gain bass extension frequencies due to the bass-trap effect of having two surfaces separated by a finite distance, but the cavity also having depth and width, thus increasing the 1/4 wavelength cancellation effects. 

 

This is a subject that is little understood by almost everyone that I observe writing on audio forums and magazines (including many engineers that design loudspeakers), and something that PWK understood well and used to great effect in his original Khorn bass bin design.  He also educated many on the subject in his writings and in one-on-one discussions...to those apparently not taking the time to read his well-written articles.

 

Chris

  • Like 1
  • Thanks 2
Link to comment
Share on other sites

6 hours ago, Chris A said:

There are at least two effects that occur when you raise a direct-radiating woofer box (acoustic suspension or bass reflex) away from the floor:

 

* You introduce an additional 1/4 wavelength cancellation frequency ("null") with the floor--which is generally above 200 Hz in the case of direct radiating woofer boxes, and at ~230 Hz in the case of horn-loaded woofers such as the Khorn when it is not sealed properly against the room's corner walls.  This is also referred to as the "Allison Effect" (for reasons that I can't explain, since Klipsch said it well before Roy Allison).  A graphic of that effect even with a flush-mounted loudspeaker on a wall is included below from Toole's book (approximating a solid riser that is discussed in this thread):

 

1077729542_TooleFigure12.9.thumb.JPG.b614511e0035b31d8d03db51971f173b.JPG

 

* You also deny the loading of the woofer cone itself to lower frequencies (the resistive portion of the complex acoustic impedance) due to the loss of room "boundary gain".  This is the major effect in the loss of its deep bass response. It is also a subject of typically great confusion among most audiophiles-especially those that place their loudspeakers away from the walls of the room instead of placing them within 12" of the walls.  Any significant disruption within the first 1/4 wavelength of the frequencies being supported by boundary loading effectively destroys the boundary gain effect, and thus truncates the bass bin's frequency extension, which is seen in the plots that PWK published in the article linked above.

 

You can read more about this subject, where the room boundaries themselves form a straight-sided trihedral horn that extends the bass response of the bass bin via horn loading (called "boundary loading" in this instance in Toole's book). 

 

1138652488_TooleFigure12.1.thumb.JPG.ecd51c12b0f2780f17cf8990cd5b6436.JPG

 

An open-legged riser under a loudspeaker further cancels the boundary gain bass extension frequencies due to the bass-trap effect of having two surfaces separated by a finite distance, but the cavity also having depth and width, thus increasing the 1/4 wavelength cancellation effects. 

 

This is a subject that is little understood by almost everyone that I observe writing on audio forums and magazines (including many engineers that design loudspeakers), and something that PWK understood well and used to great effect in his original Khorn bass bin design.  He also educated many on the subject in his writings and in one-on-one discussions...to those apparently not taking the time to read his well-written articles.

 

Chris

Thanks Chris.

These types of answers are very helpful. I won't pretend to understand all of it, but..... good stuff. 

Link to comment
Share on other sites

If you think of the boundary gain of the loudspeaker being on the floor vs. up in the air on a riser just like being horn loaded vs. having a gap between the horn and the driver...you will begin to see the magnitude of the importance of having them on the floor. 

 

Using solid-side risers under a direct radiating bass bin are like having long throat adapters between the horns and the drivers--it moves the acoustic center higher off the floor, but you pay a price of irregular on-axis frequency response at some frequency--that you can't EQ flat (i.e., they're not minimum-phase frequency response dips).

 

The physical effect of all this is providing something for the woofers to push against rather than just free air---you're using an acoustic transformer to increase the resistance that the woofer sees at very low frequencies.

 

Chris

  • Like 1
  • Thanks 2
Link to comment
Share on other sites

1 hour ago, Chris A said:

If you think of the boundary gain of the loudspeaker being on the floor vs. up in the air on a riser just like being horn loaded vs. having a gap between the horn and the driver...you will begin to see the magnitude of the importance of having them on the floor. 

 

Using solid-side risers under a direct radiating bass bin are like having long throat adapters between the horns and the drivers--it moves the acoustic center higher off the floor, but you pay a price of irregular on-axis frequency response at some frequency--that you can't EQ flat (i.e., they're not minimum-phase frequency response dips).

 

The physical effect of all this is providing something for the woofers to push against rather than just free air---you're using an acoustic transformer to increase the resistance that the woofer sees at very low frequencies.

 

Chris

Aren't the risers on the cornwalls and heresys being hollow an issue then? Or are they to short to matter?

Link to comment
Share on other sites

Thanks, Chris!  This stuff needs to be said again and again.  Because so many open legged risers are sold, and are offered for sale in catalogs and on websites, I fear that many people just assume they are a good idea. 

 

If the goal of putting speakers on risers (solid or not) is to make the tweeters ear level, I'll remind people that:

  • Certain speakers have near ear level tweeters when the speaker enclosure is sitting on the floor.  Among these are The Klipschorn (a little high), the Cornwall (a little low), and the Jubilee (?).  Even my old JBL rear loaded horn, the C34 had ear level speakers.  A La Scala can have a very small, solid DIY riser/tilter put under it to aim its tweeters at the ears.
  • Of course, a lot depends on the height of the listener, and the height of the seat.   When my wife and I sit on our couch, both of our ears end up between 42" and 48" off the floor.  That puts my ear canal just about the height of a midline between the Klipschorn tweeter and the midrange horn.  Close enough, at 13 feet away.
  • I think Klipsch used to say that putting a flash light at the height of your ears (but in front of your nose) and directing the beam at the speakers, if you could see the entire bug screen in the tweeter, you were in good shape.  IIRC, this was in a pop article -- was it by Craig Stark?  Maybe, maybe not.
  • Thanks 1
Link to comment
Share on other sites

36 minutes ago, garyrc said:

Thanks, Chris!  This stuff needs to be said again and again.  Because so many open legged risers are sold, and are offered for sale in catalogs and on websites, I fear that many people just assume they are a good idea. 

 

If the goal of putting speakers on risers (solid or not) is to make the tweeters ear level, I'll remind people that:

  • Certain speakers have near ear level tweeters when the speaker enclosure is sitting on the floor.  Among these are The Klipschorn (a little high), the Cornwall (a little low), and the Jubilee (?).  Even my old JBL rear loaded horn, the C34 had ear level speakers.  A La Scala can have a very small, solid DIY riser/tilter put under it to aim its tweeters at the ears.
  • Of course, a lot depends on the height of the listener, and the height of the seat.   When my wife and I sit on our couch, both of our ears end up between 42" and 48" off the floor.  That puts my ear canal just about the height of a midline between the Klipschorn tweeter and the midrange horn.  Close enough, at 13 feet away.
  • I think Klipsch used to say that putting a flash light at the height of your ears (but in front of your nose) and directing the beam at the speakers, if you could see the entire bug screen in the tweeter, you were in good shape.  IIRC, this was in a pop article -- was it by Craig Stark?  Maybe, maybe not.

Good stuff thanks. 

Link to comment
Share on other sites

On 6/26/2019 at 5:30 PM, Chris A said:

The physical effect of all this is providing something for the woofers to push against rather than just free air...

 

I thought of this topic driving home from a trip Sunday.  There was a mostly steady-state hard wind from the left going down the freeway.  You know, how you have to "lean" into it to stay going straight.  Until you get on an overpass.  Whereupon the side-force mostly disappears.  Until you get to the other side with no free-air space underneath the roadway, then it's time to lean again.

 

As a corollary, in the case of low frequencies produced by a loudspeaker, you want the no-gap-under situation so the (what would/should be) pressure changes/differentials achieve maximum effect. 

Link to comment
Share on other sites

6 hours ago, YK Thom said:

A question: why would the venerable JBL L100 (and it’s modern reincarnation) have stands designed for them? They were low, about eight inches tall and slanted back. 

 

So they would be high enough for your cat to want to sit on.

  • Haha 2
Link to comment
Share on other sites

Personally I love the look of the Heresy, for me there is a certain class about them in the look department with grill cover on. however I often wonder if I were ever to be so lucky enough to own a pair what part of my body would receive the best sound, my knees or my ears. 

 

They just seem low to the ground.  I cant really comment on how they sound as unfortunately I have never heard a pair.  Maybe looks are deceiving in this aspect in regards to sound.  I know the HIII are elevated somewhat but still.  

Link to comment
Share on other sites

If you don't buy them with the sloped risers, or by them without, you can use a piece of 2x4 or 2x2 can be placed under the front edge to tilt them back to point them more toward the ear. That won't hurt the bass any.

Link to comment
Share on other sites

With Heresy speakers (some have asked about) I;

1) Converted to Super Heresy, including very nice B&C woofers +bass

2) Placed in corners +bass

3) Raised on custom built stands to place midrange at ear level  -bass

4) Stands were open, four leg all wood -bass

5) Add Velodyne sealed, DD10 subwoofer on 2inch rigid insulation +SVS sub feet +bass.  One per Heresy makes for a nice combo.

 

This has accomplished the ear level, + bass enhancement.  Sorry for poor photo, the wiring mess, and oh ... the Patriots Man Cave stuff.

image.thumb.jpeg.bc6c06587d3ed1777122e8498e2457b5.jpeg

  • Like 2
Link to comment
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...