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Henry Kloss "Loudspeaker Design - Hoffman's Iron Law"

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Posted on February 19, 2019 at 03:03:18
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 Henry Kloss - Hoffman's Iron Law March 1971 AUDIO (a very good issue)

(.. a fact which which Mr. Klipsch apparently likes to frighten small children) - lol









Karlson Evangelist

 

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RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on February 19, 2019 at 09:14:18
Scott L
Audiophile

Posts: 353
Location: Knoxville
Joined: February 2, 2001
 Yes, agreed. This is how I learned it, anyway. For bass, you will need box size to get decent efficiency.

As an example, for a 5.2 cubic ft.(net) one possibility is a Parts Express Dayton DC300-8 QB3 tuned to 25Hz, -3 @ 28Hz. A REAL TRUE 90db/w

If that's not enough (since this is a low-cost driver, anyway) simply double up. With 2 per channel, 96db (4ohms)(high-current amp) you could go with reaction-forced vibration cancelling. A pair of 10.4 cubic foot (net) enclosures should be no problem in the understanding WAF dept. :)

 

iron Hoffman meets a panel., posted on February 23, 2019 at 06:34:32
Cleantimestream
Audiophile

Posts: 7550
Location: Kentucky
Joined: June 30, 2005
 Curious, Henry Kloss makes mention of THAT particular frequency range, because the area of 200 to 500 Hz IS the weak area of a Khorn Bass bin and there is no piston box on the planet that can equal the sound of a panel speaker in THAT same frequency range.
I still miss what my old Magnepan Tympani I's speakers did between 200 and 800 Hz and no equalizer can change or induce that clarity or tactile realism I remembered.

Wilson Watt puppy VII's fell flat in that frequency range just as easily as the Khorns did.


The Mind has No Firewall~ U.S. Army War College.

 

RE: Twas ever thus...., posted on February 23, 2019 at 09:25:21
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 The Kloss quote about PWK is hilarious! The article ends on p. 56, but I mistakenly started reading the end of another article above it on the same page: Doppler Distortion AGAIN? by Roy Allison. In it Allison concludes that since there is modulation distortion in the tape recording and vinyl systems, a little more in the speakers can't hurt ya a whole lot. Also referenced in that issue is: The Mud Factor by Paul W. Klipsch from the October 1970 issue of Audio which apparently inspired the Allison article and the Kloss quote. Previous to this was the article Doppler Distortion In Loudspeakers by Roy V. Childs from the August 1970 issue of Audio where that author actually built a rig to test modulation distortion, and discussed other writers who did experiments where it was at times audible. And there is humor in many of these articles! Unlike the neurotic wine snobbery which is the norm in many of the high end magazines nowadays. Much of this parallels the wire controversy which can be seen on some of the forums here in the present time. The argument usually goes: since theoretically wires can't have audible effects, then it's a waste of time trying to see if they do. At the other end of the argument are those who claim night-and-day differences.

Paul

 

RE: Twas ever thus...., posted on February 23, 2019 at 11:56:15
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 Having met both Henry and Paul I find that really amusing, especially in the context that T/S had not yet made its appearance in the US, so both of them were about to endure the onslaught of ported cabs that would knock both horn loaded and acoustic suspension cabs almost completely out of the marketplace. Both were at that point blissfully unaware of what was on just over the horizon.

 

RE: Twas ever thus...., posted on February 24, 2019 at 10:42:20
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 really cool - I have awesome respect for Henry Kloss's talent as a transducer and speaker designer with regards to the original KLH products. (I never heard any of the Cambridge line) - those 10" woofers used in the 17 and Six sound great today after a half century - and better than many more expensively made drivers from their time (plus better than a lot made today) Kloss well understood system Q vs driver Q. (how much did he learn from Vilchur?)

That issue did gang up on PWK ;^)
Karlson Evangelist

 

RE: Twas ever thus...., posted on February 24, 2019 at 11:36:02
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 Henry was a student of Ed's, hired by Ed to build Ed's designs. Ed was originally the idea man, Henry the one who translated the ideas into reality.

 

RE: Twas ever thus...., posted on February 24, 2019 at 12:15:05
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 Henry certainly learned well. Proper air suspension "bookshelf" speakers were a revolution which helped make stereo widespread and practical. (and was going to say "affordable" but AR3a were relatively expensive - ~1970 the local college had AR amps, turntables and speakers - which sounded quite good - the music appreciation room had cinder block walls, and very little absorption other than its students - that worked well with the AR3a on classical music.
Karlson Evangelist

 

RE: iron Hoffman meets a panel., posted on February 24, 2019 at 12:30:28
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 I had Tympani 1D - great in ways. Here's an EV Sentry IV loaded with Pyle pym1298 (~same as Eminence Kappa12a) vs Khorn with K33 CTS - not much low end on the Sentry but pretty strong in that region


Karlson Evangelist

 

RE: Twas ever thus...., posted on February 24, 2019 at 13:00:17
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 At one point AR had a 70% market share, which is crazy.

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on February 24, 2019 at 16:55:47
claudej1@aol.com
Audiophile

Posts: 816
Location: Detroit
Joined: August 17, 2007
 I read the whole thing. Goes to show you how much the mass market is willing to compromise to get smaller speakers than a Klipschorn.

What the article FAILS to mention is the Amplitude Modulation sidebands that are created and NOT part of the original music, hence the reason why horns sound "cleaner" AND more dynamic than small direct radiators.

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on February 24, 2019 at 19:36:00
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 Henry wasn't ignorant of the shortcomings of his speakers, he just wouldn't admit them publicly. A year after he wrote that I listened to his personal system in his office. It consisted of four Large Advents. They were stacked two per side, the upper cab inverted, creating an M-T-T-M. I'd never seen that done before, so of course I asked him why, especially as he didn't play them particularly loud. He said that the 6dB increase in sensitivity significantly lowered THD since the drivers didn't have to work as hard. I said that they sounded great and that he should make a speaker like that in one box. 'Too big' he replied. 'People want smaller, they don't care what it sounds like'. He then made a less than flattering remark about what Amar Bose was doing down the road.

Two years later I heard PK's personal system, which was equally interesting. He had a KHorn in the left and right corners and a Heresy centered on the wall in between them. He said it was the only way to get a real concert hall experience. It did sound good. I asked him why he had the diffraction horns in his speakers on the wrong axis. He said the dispersion wasn't that bad, and besides, if he had them vertical people would think it looked wrong and wouldn't buy the speakers.

Neither of these geniuses was above doing what they needed to do to sell their products. Principles don't pay the rent.

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on February 28, 2019 at 09:07:50
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 That was a facilitating read! I wonder if the Heresy was tweeted. I have never been a fan of the stock Heresy and I used to sell them.

Dave

 

RE: Twas ever thus...., posted on February 28, 2019 at 09:10:22
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 I have heard Cambridge speakers. For what they are, they sound very good.

Dave

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on February 28, 2019 at 10:36:53
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 The Heresy was bone stock, so were the KHorns and the Advents. I'd almost take credit for the invention of the sub/satellites, because I built such a system in 1972. I had a corner horn loaded with two eights, each separately driven with L and R channel feeds, low passed at 100Hz for summed lows. A pair of 1x8 two way bookshelves high passed at 100Hz were set to either side. Henry heard it and liked it. I think it might have influenced what he later did at Cambridge Sound Works, but it wasn't an original concept on my part, I'd seen something similar in a magazine.

 

You Don't Understand, posted on February 28, 2019 at 13:26:48
Inmate51
 The Electro-Voice Sentry IV wasn't intended to be a home hifi speaker. It was an auditorium sound reinforcement speaker.

 

RE: You Don't Understand, posted on February 28, 2019 at 14:34:11
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 The A7 wasn't intended for the home either, but plenty of them made their way there.

 

RE: You Don't Understand, posted on March 1, 2019 at 07:16:42
Inmate51
 My point was simply that the Klipsch was designed to be in a home, with boundary assistance. The E-V Sentry IV was not. "Apples and oranges". The E-V Sentry III would have been a better comparison with the Klipsch.

Anyway, since you mentioned it, both the Sentry III and the Sentry IV blew the socks off the A7.

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on March 1, 2019 at 09:56:25
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 Interesting! The sub/satellites is a very viable concept, even when the sateliltes are Heresys!

Dave

 

Good read , Thanks! (nt), posted on March 2, 2019 at 09:30:25
Wojciech
Audiophile

Posts: 4120
Joined: June 23, 2009
 nt

 

RE: You Don't Understand, posted on June 13, 2019 at 06:31:12
rafal_poland
Audiophile

Posts: 2
Joined: June 12, 2019
 Hello,

I am new owner of EV Sentry III (previously JBL4343, EV Interface D, Altec19).
I recapped the crossovers + lift them (ear level = middle between mid-horn and tweeter)

I've got kind request regarding the speaker placement.

My room is as below noted (this is nearly square, unfortunately...) and I use shorter wall.
Speakers are placed right up against the back wall (according to the recommendation).
Now these are 9,5 ft apart (center to center), 14 ft from my listening position.
No toe in (I found that you rather recommend on axis - I need to try).

Can you share your experiences and tell me what is/was your placement, distances, etc?
Maybe you've done some tests with different distances apart or toeing them in (on/off axis) - crossing in front or rather behind my head?

Many thanks in advance!

My System
Turntable Pioneer PL 70 mkII
amp Heatkit W4B
EV Sentry III

My Room
17,5 x 20 ft
Acoustically treated - side walls / corner bass traps / ceiling

Music
60-70's rock / blues / jazz - 70%
Modern rock / blues / jazz - 30%


Greetings from Poland!
Rafal

 

EV Sentry III, posted on June 13, 2019 at 06:33:54
rafal_poland
Audiophile

Posts: 2
Joined: June 12, 2019
 Hello,

I am new owner of EV Sentry III (previously JBL4343, EV Interface D, Altec19).
I recapped the crossovers + lift them (ear level = middle between mid-horn and tweeter)

I've got kind request regarding the speaker placement.

My room is as below noted (this is nearly square, unfortunately...) and I use shorter wall.
Speakers are placed right up against the back wall (according to the recommendation).
Now these are 9,5 ft apart (center to center), 14 ft from my listening position.
No toe in (I found that you rather recommend on axis - I need to try).

Can you share your experiences and tell me what is/was your placement, distances, etc?
Maybe you've done some tests with different distances apart or toeing them in (on/off axis) - crossing in front or rather behind my head?

Many thanks in advance!

My System
Turntable Pioneer PL 70 mkII
amp Heatkit W4B
EV Sentry III

My Room
17,5 x 20 ft
Acoustically treated - side walls / corner bass traps / ceiling

Music
60-70's rock / blues / jazz - 70%
Modern rock / blues / jazz - 30%


Greetings from Poland!
Rafal

 

RE: You Don't Understand, posted on June 13, 2019 at 08:57:37
Inmate51
 You've got a very nice pair of speakers! Place them where they sound best to you.

 

RE: Henry Kloss "Loudspeaker Design - Hoffman's Iron Law", posted on May 21, 2022 at 13:04:01
drmoran@aol.com
Reviewer

Posts: 5
Joined: April 5, 2004
 Weighing in just cuz this post is not that old --- we must be careful to spell Hofmann's name correctly, as (of course) Henry did in the article. (Anton was the son of about the most famous pianist of prior decades, Josef.)

Second, just for the record, while this was a handy way of thinking of the variables, it had been properly delved by 1964 in AESJ papers by Allison and Villchur.

 

RE: Twas ever thus...., posted on May 26, 2022 at 21:01:55
arhpg
Audiophile

Posts: 8
Location: Southeastern US
Joined: April 27, 2006
 Acoustic Research never had 70% market share; in 1966 the company had 32.6% of the US domestic loudspeaker market.

 

RE: Twas ever thus...., posted on May 26, 2022 at 21:09:58
arhpg
Audiophile

Posts: 8
Location: Southeastern US
Joined: April 27, 2006
 This information is basically correct. Henry Kloss did not have anything to do with the design of the acoustic-suspension woofer; it was 100% Edgar Villchur's design, but once the two had incorporated Acoustic Research, Inc. in August, 1954, Henry did approximately 75% of the production implementation on the first speaker, the AR-1, before it went into production in the early spring of 1955.

 

RE: spell Hofmann's name correctly, posted on May 27, 2022 at 07:02:36
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 Tony never made a big deal about the misspelling of his name, which he knew was because of the fame of that other Hoffman, Dustin. It's difficult to separate the contributions to the art made by Hofman, Roy Allison, Hank Kloss, Malcom Low and Ed Villchur, but there was no disagreement among them that the honor of having the iron law named after him belonged to Tony.

 

RE: spell Hofmann's name correctly, posted on May 30, 2022 at 18:54:51
arhpg
Audiophile

Posts: 8
Location: Southeastern US
Joined: April 27, 2006
 "Tony never made a big deal about the misspelling of his name, which he knew was because of the fame of that other Hoffman, Dustin. It's difficult to separate the contributions to the art made by Hofman, Roy Allison, Hank Kloss, Malcom Low and Ed Villchur, but there was no disagreement among them that the honor of having the iron law named after him belonged to Tony."

Perhaps it would have been more accurate to say, "It's difficult *not* to separate the contributions to the art...-." For example, when you consider the contribution of Villchur's acoustic-suspension woofer and the dome tweeter, it's hard to consider anything done by Hofmann or Low that would be considered in the same light. Edgar Villchur, Henry Kloss and Roy Allison did a great deal to improve existing loudspeaker technology, and these men stand out in their contributions. Hofmann and Low were associates and simply weren't in this same class. The proper spelling of Hofmann's name is a minor footnote in audio history.


 

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