Jump to content
The Klipsch Audio Community
Sign in to follow this  
ghostmouse

Forte III lifts?

Recommended Posts

There are some even here who say to lift them.  Mainly I disagree, but----if you sit in a high chair you might benefit from raising the level so the tweeters are at ear level.  If you sit on a couch to listen and the tweeters are near enough to ear level then don't lift them.  If you listen curled up in a basket, then you are probably a cat, and good luck.

  • Like 1
  • Haha 1

Share this post


Link to post
Share on other sites

If they are lifted by placing them on a solid object that has a firm surface across the front, sides and back it might be O.K.  What you don't want is a cavity under them.  Cavities (i.e. legs) reduce the deep bass.  The only reason I can think of to raise them would be to get the tweeters to be at ear level.  Most couches, etc are low enough so, as oldtimer says,  the tweeters will be near enough to ear level.  The Forte III was probably designed and voiced to be sitting on the floor. 

 

Another variable is what is behind the speakers.  The guy in the video has a couple of windows behind the nice big passive radiators.  Normal thin window glass doesn't contribute much to boundary gain (in the bass).  Thicker glass, as in sliding glass doors, isn't so bad, unless the doors wiggle, which some do.  Good, firm walls are the best of all.

 

I hope the video guy's cat doesn't like to shred speaker cones, which some do.  Those passive radiators look awfully tempting.  One of the guys that used to be at Klipsch had a cat who ate the woofer surround.  [I love cats; I'm on my 6th.  They have always been banned from the music listening room, which meant they spent a great deal of time trying to sneak in there.]

 

Did the video guy guess that the Forte I came out in the '70s?  They were first manufactured in 1985, and got one of the best reviews ever in High Fidelity magazine.

 

The following was written by Paul Klipsch:

 

Eight Cardinal Points of Reproduction 

 

1.Freedom from distrortion. Minimum distortion requires small amplitudes of air mass movements, even at peak transient power output. Bass diaphragm motion should not eceed 1/16 inch. Corner placement reduces distortion three fourths.

 

2.Optimum size of speaker. Large enough to reproduce the lowest audible bass tone at peak transient power output without distortion; not so large as to produce a separation of bass and treble events. Corner placement increases effective size of speaker 4 times.

 

3.Freedom from rattles.

 

4.Freedom from shadows. Obstructions between high frequency speaker and listeners can not be tolerated - treble wave-lengths do not turn corners. 

 

 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 2 octaves.

 

6.Adequate spacing for stereo. In a 14 x 17 foot room, for example, the 17-foot wall is apt to be best for the stereo speaker array.

 

7.Accurate spatial values. Ability to localize the virtual sound sources in their original spatial relationships requires 3 widely spaced speakers, regardless of size or type, retention of this quality over a wide listening area requires toe-in of the flanking speakers.

 

8.Flanking speakers toed-in. Such toe-in is naturally provided by corner speakers. The effect is to reduce shift of the virtual sound source for different listener locations. This is the only way to achieve a wide area for listening. 

 

 

 

 

  • Thanks 2

Share this post


Link to post
Share on other sites

garcyrc, are you aware of any specific data on the cavity effect?  I'm wondering if PWK ever published data on this.  I'd like to understand it better, as I do not have a good grasp on the physics.

 

It's clear that boundary effect is increased when a speaker is on the floor.  If the speaker is raised, the boundary effect is reduced.  Is this what PWK meant in point 5?

 

However, if a speaker were raised on a solid stand (no cavity), the boundary effect would not change vs. being on legs (or would it?), and the speaker would not perform as if it were on the floor, right?  

 

This is relevant to my Forte I, which are  on ~24" risers/legs to get the tweeters closer to ear level when standing in the unfinished portion of my basement.  I would consider enclosing the risers to eliminate the cavity, if that were known to improve the bass performance.

 

Share this post


Link to post
Share on other sites
7 hours ago, adam2434 said:

garcyrc, are you aware of any specific data on the cavity effect?  I'm wondering if PWK ever published data on this.  I'd like to understand it better, as I do not have a good grasp on the physics.

 

I haven't seen any.  The history guys in that section might know, as might someone reading this now.  I know that PWK was shocked/angered by a negative review in some magazine that cited "no bass response" and gave data.  PWK was unable to come up with bass that week until he put the speaker in question up on a stool (height unknown). 

 

7 hours ago, adam2434 said:

 

It's clear that boundary effect is increased when a speaker is on the floor.  If the speaker is raised, the boundary effect is reduced.  Is this what PWK meant in point 5?

 

I think so.

 

7 hours ago, adam2434 said:

However, if a speaker were raised on a solid stand (no cavity), the boundary effect would not change vs. being on legs (or would it?), and the speaker would not perform as if it were on the floor, right?  

 

I think something that might be called boundary effect would be reduced more on legs than on a solid stand (no cavity).  As I understand it, if the bass is not reinforced as much by the floor, because the floor isn't there until farther down, the bass is attenuated.  It used to be standard practice in movie theaters to fit the behind the screen speaker cabinets with thick, braced plywood "wings" on either side of the cabinets and above and below them, to reinforce bass.  If the theater was the multipurpose type, with stage performances, too, the speaker cabinets would be on rollers to roll them out of the way, but the plywood extension of the baffle still went down in front of the rollers, to about one inch of the floor.

 

7 hours ago, adam2434 said:

This is relevant to my Forte I, which are  on ~24" risers/legs to get the tweeters closer to ear level when standing in the unfinished portion of my basement.  I would consider enclosing the risers to eliminate the cavity, if that were known to improve the bass performance.

 

If you have some lumber, you could tie or wedge a piece (firmly) to the front of the risers (back, too, if the Forte I has either a rear firing port or a passive radiator in the back), and see if it makes a difference.  Or run REW, if you have it.  If it does make a difference, you could permanently enclose the risers.  Firmness is important.  When we rebuilt a room, giving it firm walls instead of the floppy ones the former owner had put into his DIY project, it made an audible difference in the bass.

 

Do you listen to music standing up, sitting down, or both?  Are you going to finish that part of the basement?  Over our studs, we put in 3/4 plywood sheeting covered by 5/8 sheetrock, with seams staggered and glue put between the layers, to prevent vibration.  It made nice, firm walls.

 

Good luck!

Share this post


Link to post
Share on other sites
11 hours ago, garyrc said:

If you have some lumber, you could tie or wedge a piece (firmly) to the front of the risers (back, too, if the Forte I has either a rear firing port or a passive radiator in the back), and see if it makes a difference.  Or run REW, if you have it.  If it does make a difference, you could permanently enclose the risers.  Firmness is important.  When we rebuilt a room, giving it firm walls instead of the floppy ones the former owner had put into his DIY project, it made an audible difference in the bass.

 

Do you listen to music standing up, sitting down, or both?  Are you going to finish that part of the basement?  Over our studs, we put in 3/4 plywood sheeting covered by 5/8 sheetrock, with seams staggered and glue put between the layers, to prevent vibration.  It made nice, firm walls.

 

Good luck!

The risers are platforms bolted to sheetrock-covered studs, and have 2x4 legs in the front.  The other side of the wall is in the finished portion of the basement and also has sheetrock.

 

With the addition of a little framing and some plywood, I can cover the front and sides of the platforms, which would totally enclose them.

 

Listening is 90% standing up , when my son or I am using exercise equipment ,or I am messing with something on the workbench.

 

I have been thinking about investing in a calibrated mic and REW.  It would be very interesting to understand how our various speakers are performing in different rooms in the house.  It would also be cool to understand the impacts of speaker placement, toe, enclosing the Forte I risers, etc.  My only reservation with REW, is that the results could send me down the rabbit hole of trying to "fix" the response in multiple rooms/systems.  :)

  • Like 2

Share this post


Link to post
Share on other sites
On 11/7/2017 at 12:40 AM, garyrc said:

 

The following was written by Paul Klipsch:

 

Eight Cardinal Points of Reproduction 

 

1.Freedom from distrortion. Minimum distortion requires small amplitudes of air mass movements, even at peak transient power output. Bass diaphragm motion should not eceed 1/16 inch. Corner placement reduces distortion three fourths.

 

2.Optimum size of speaker. Large enough to reproduce the lowest audible bass tone at peak transient power output without distortion; not so large as to produce a separation of bass and treble events. Corner placement increases effective size of speaker 4 times.

 

3.Freedom from rattles.

 

4.Freedom from shadows. Obstructions between high frequency speaker and listeners can not be tolerated - treble wave-lengths do not turn corners. 

 

 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 2 octaves.

 

6.Adequate spacing for stereo. In a 14 x 17 foot room, for example, the 17-foot wall is apt to be best for the stereo speaker array.

 

7.Accurate spatial values. Ability to localize the virtual sound sources in their original spatial relationships requires 3 widely spaced speakers, regardless of size or type, retention of this quality over a wide listening area requires toe-in of the flanking speakers.

 

8.Flanking speakers toed-in. Such toe-in is naturally provided by corner speakers. The effect is to reduce shift of the virtual sound source for different listener locations. This is the only way to achieve a wide area for listening. 

 

 

 

 

 

I've never seen this before, but I'm stealing it if it came from the man.  

  • Like 2

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.

Sign in to follow this  

×
×
  • Create New...