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

[Tom Mobley]

Wow, whatta blast from the past! This was when I first got my Khorns.

[LarryC]

Tom, weren't you the forum member who discovered some kind of similar bass throat inserts in his own K-horns? (The story must be in another thread.) Someone did or suspected it, and I think decided agains taking them out based on measurements over subjective listening evaluation. I think yours and mine were made around the same time IIRC.

Larry

[lorcoll]

Hi.

I have a question for LarryC:

I have two pairs of  Khorn (1973 and 1984 year).

The two pairs differ in the motorboard rail that 1984 don't have and for the size of the pyramidal blocks (inserts) inside the 3"x13" hole on the fix motorboard (the 1984 blocks are smaller).

The pics of your mod are now not visible, so I would know if I have to reduce the Pyramidal blocks in the 1973 Khorns or I have to eliminate them definitely.

I have already screwed the woofer directly onto the motor board in the 1973 one.

I have attached pics of the two types. 

[lorcoll]

They use K33P in the 1973 Khorn and K33E (square magnet) in the 1984 speakers.

[LarryC]

15 hours ago, lorcoll said:

 

Hi.

I have a question for LarryC:

I have two pairs of  Khorn (1973 and 1984 year).

The two pairs differ in the motorboard rail that 1984 don't have and for the size of the pyramidal blocks (inserts) inside the 3"x13" hole on the fix motorboard (the 1984 blocks are smaller).

 

The pyramidal blocks are the "splitters" which are apparently fundamental to the throat design.  They apparently have been in every K-horn bass bin since time immemorial.  You are confusing them with the pyramidal blocks that I described.  You should not mess with them or try to reshape them in any way, IMO.

 

You should look for bass horn expertise, such as Dana (D-man), if you can reach him, or Jim Hunter, if you want an explanation of what the splitter does and why it's there.  The subject is extremely complicated, involving bass wave lengths and directions and the like.

 

Note that the splitters are mounted on the BACK of the FRONT PANEL of the bass bin.  They are immediately opposite the 13" X 3" slot, and on the front side of the horn throat passageway.

 

The blocks I referred to are different.   Those were on the FRONT of the MOTORBOARD, just above the 3" X 13" slot.  This placed them on the back side of the horn throat passageway, opposite to the splitter.  The splitters are on the FRONT side of the first stage of the bass horn, while the pyramidal blocks were on the  BACK side of that passageway.

 

The bottom line is that you should not fool with the splitters!  These are entirely different from the blocks I was talking about.  You would probably destroy some important way the bass horn throat works.  There is no need to do that.

 

The pyramidal blocks were a short-lived modification in K-horns made around 1971-73.  They were gone by 1974.  No one could recall their purpose by 2004.

 

Also, be hesitant to remove the mounting board and rails, if you have them.  That setup provides a longer passageway at the entry to the throat of the bass horn, so that removing anything in that area will alter the geometry of the bass horn throat, likely not in a good way.

 

I think you may be trying to misapply what you're reading in my thread, which I don't think you fully understand, for an unstated purpose.  What problem are you trying to solve?

 

I can try to dig out those old pictures, but it wouldn't be easy.  I don't think you'll need them.

[lorcoll]

Ok, I think I have understand now.

I don't speak english well (I live in Italy) and I have misunderstand your explanation for sure.

But for the mounting board and rails you  screwed the woofer directly onto the motor board with positive effects; why don't have I to remove them? 

I thought this was fully clear for me.

Thank you for the reply.

Lorenzo