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Restoring the standard bass horn throat in a '62 pair of Klipschorns


LarryC

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Somebody here posted the same question about some '60-ish Khorns that DID INDEED have the same throat inclusions as you described. He included a drawing in his thread.

The forum member concensus has it that they were included as some sort of a test at the time for a new woofer or something. No definitive answers from KlipschCO on it.

DM

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Wow, great stuff Larry. Glad you finally achieved what you were looking for. I will have to take a look see inside my '67's for these blocks, after I pick them up on Sunday of course2.gif.

Fini...I used to love Clutch when I was a kid, what was the dogs name, "paddle foot"?

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On 3/17/2004 4:21:12 PM Tom Mobley wrote:

...After I first got them set up I got out one of the Stereophile test CD's and tried it, seemed like the response died off between 40 and 50Hz....

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Tom,

While I don't have measuring equipment, I've used certain recordings to get a qualitative handle on deep bass from my K-horns. The Bach Passacaglia in C minor for organ heads right down to a low 32.7-Hz "C" within seconds of opening, and the Saint-Saens "Organ" symphony reaches low 34-Hz D-flats in the slow movement. There may be a problem if you can't hear and feel those low tones. These were very weak on my K-horns before the inserts were removed, but are nice and strong now.

According to those factory notes, the inserts were used between 1961 and 1963. It would be interesting if yours had them, too.

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Larry, I echo Q-man's words, your elegantly depicted saga in words and photos have opened my eyes and the re-thinking probably saved my ears from disappointment of timbre-matching six Khorns of various vintages.

Once again, the shades and nuances within a fully horn-loaded enclosure are given the respect and concern they so richly deserve... a place where the much used term "awesome" truly fits. Your workman-like approach was not marred by bringing in a pro to "whack, smack pry & tease" out the offending blocks. May you enjoy your new found "ear-fortune" for 20 more years... and then some!

Your story and perseverance are indeed amazing... as is the support that you received from Klipsch... particularly Ernie (who signed my copy of PWK's biography... in addition to Miss Valerie, the authors). HornEd

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When taking out the removeable motor board & mounting directly to chamber motor board. You have slightly increased the back chamber volume. This probably changed woofer EMF slightly. It might not be measureable. But could be audible as better defenition. To make measurements you need some thing better than a rat shack meter & stereophile test cd. You also need to disconnect mid & tweet if you do a sweep test for rattles .

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On 3/18/2004 7:36:48 AM Tom Mobley wrote:

I'll look around for those recordings. What labels were they on? Something I could find at Amazon?

Tom

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Tom,

Many recordings of the organ works; I have a favorite oldie on Columbia, Bach Great Organ Favorites by E. Power Biggs, CBS MK 42644. The Passacaglia is on track 13. Others might chime in with their favorites.

A long-standing, spirited favorite of the Saint-Saens is also an oldie but has good deep organ pedal: Boston Sym under Charles Munch, RCA 09026-61500-2. The slow movement starts on track 2. The last movement (track 4) also has the organ, which goes to the 32.7 C at the ending.

Hope this helps.

Larry

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All I know is what I was told (in 1994), that some statement in Klipsch files said this was a change in 1961-1963. Perhaps more details are available from Klipsch.

Barring that, I suspect the only way to know is to go into the bass bin, take out the woofer, and look. My pics should help you determine it right away. Removing the woofer in K-horns of that vintage requires removing the wingnuts and angle iron from the side nearest the bin opening, loosening the wingnuts considerably on the far side, pulling the board away from the motorboard, and sliding it out. I did find, though, that the weather-stripping sealing the mounting board to the motorboard was deteriorated and gummy, so you may need to have new stripping handy to remount the board.

Hope this helps.

Larry

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  • 2 years later...

Do the newer and brand new ones use the removable motor board my, 74s have the board.Should all of us who have the removable motor board think about removing it and screw woofer directly???I also think everyone should do air tightness test of woofer air chamber its not hard to test>Rick

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Has anyone else done this mod?Looks easy enough to do i would like to do this if its worth the effort i am kinda worried about putting screw holes in my motor board, i guess i could fill them up if i didnt like the mod.Rick

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looking a the inserts...and drawing on some assumptions made from reviewing cab designs....my take is that you probally are correct to expect a change in the lower end as you discribe because the mod has the characteristics of phase plug which appears to be targeted to extending the upper portion of the bass area. extending the upper range of the k-horn has been the subject of a lot of intrest.

as in any mod, there is a trade off...if you leave the mod in...perhaps it improves the upper bass and lower mid-bass area....if you take it out...lower bass response improves...but upper bass region/lower-mid bass returns to the pre-mod state.

on the subject of mod's to the k-horn bassbin that is now-destructive, and reversable.....check out this link

http://www.speakerbuilding.com/content/1032/

the link has some response graphs that goes into more detail about the trade off betweem improving the low end bass response at the expense of reducing the mid-bass region's presence.

let me know if I need to clarify any of my comments.

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intresting..before seeing the graph, I posted a comment in another thread about the clear midbass in a 6X13 opening as opposed to a 3X13 one. was happy to see the improved 250HZ plot on the 6X13 graph.

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  • 6 years later...

The narrower slot has less deep bass, more midrange in the 400hz area.

It's not a big difference, but remember that at levels around 90dB at 40hz the lines of equal loudness are only about 3dB apart, so it can sound almost twice as loud (where as in the midrange the lines are about 10dB apart).

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