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4 x K-55M adapter (K-4M): uses?


Droogne

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" For how many people was that installation? "

 

The biggest inside was around 1300 people, outside, maybe 5,000. I slagged the MCM tweeter arrays on an outside gig, the bending elements all developed cracks.

 

A block of four bottoms was wired series-parallel to present a 4Ω load to the amplifiers, six would have been a 2.7Ω load. The 400W/4Ω Altec 9440 was my preferred bass amp, elecronically crossed at 200hz to the mids, electronically crossed at 800hz to the K401 pairs, passively crossed at 4Khz to the MCM piezo arrays (HF and VHF driven with a McIntosh MC2120).

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On 13-11-2017 at 6:36 PM, HDBRbuilder said:

LaScala plans for the ones being built in 1977 time frame. 

You can adjust these overall dimensions for thicker bass bin BOX plywood, but if you intend to use thicker plywood for the doghouse section then you will need to make major changes to the given dimensions in order to ensure the bass horn lens is sized correctly. 

Don't ask me for the cut list, though, because the factory cut list doesn't exactly help out DIY folks because it is for mass production instead of individual units.

1977LaScalaDim1.jpg

1977LaScalaDim2.jpg

Yeah, I'll probably stick with the 3/4" in the inside and adjust it for 1" sides. Shouldnt be to hard to calculate. Thanks! 

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22 hours ago, djk said:

" For how many people was that installation? "

 

The biggest inside was around 1300 people, outside, maybe 5,000. I slagged the MCM tweeter arrays on an outside gig, the bending elements all developed cracks.

 

A block of four bottoms was wired series-parallel to present a 4Ω load to the amplifiers, six would have been a 2.7Ω load. The 400W/4Ω Altec 9440 was my preferred bass amp, elecronically crossed at 200hz to the mids, electronically crossed at 800hz to the K401 pairs, passively crossed at 4Khz to the MCM piezo arrays (HF and VHF driven with a McIntosh MC2120).

I think I kind a misunderstood :s You used the LaScala bins in combo with the complete MCM 1900 array? Or with LaScalas instead of the MWM bins? And if you mean mids, you mean a different set of drivers as the K401 horns? Like a MSSM?  Also what are the specs on those MCM Piezo arrays? Cant seem to find any info on them. 

 

That aside: .... Ö Would have loved to have met that setup ! Pure powerrrrr

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23 minutes ago, Droogne said:

Yeah, I'll probably stick with the 3/4" in the inside and adjust it for 1" sides. Shouldnt be to hard to calculate. Thanks! 

Wherever you wil have overlapping panels, such as the top of the cabinet to the sides, be sure to cut the top, for example, a little bit "proud" on its left and right so that it has a very fine "lip" overlap when installed...then you just putty-up any voids in the plys on the sides and sand it flush to the sides.  You can do the same for where the side panels meet the speaker "woofer door" or "bottom" panel...let the sides be a bit proud at the bottom edge and just sand them flush after assembly. 

 

Tolerances are 1/64" or less...with emphasis on the "LESS" wherever possible.   This is ESPECIALLY important for al the pieces involved in the woofer horn section due to the need to eliminate any possibility of "air leaks" from the "doghouse" section.  You want all the sonic energy going through the compression slot and firing into the bifurcated horn-pathway lenses.  Energy lost to "air leaks" from the doghouse will be noticeable, for more than one reason....they will be audible, also!  It is also important because ..elimination of "air leaks" helps to reduce the excursion length at higher volumes...so that your woofer drivers won't be as readily capable of slamming.  When the cone goes outward, the vacuum effect behind it in the doghouse reduces its outward excursion...and vice versa...when the cone is moving rearward, the air overpressure inside the doghouse does the same thing...reduces the rearward excursion length.

 

If you are good at "splitting 1/32" when cutting you will be good to go...anything not cut "square" will create unique problems when assembly begins....have you ever seen a LaScala with a "twisted" bass bin section of the cabinet??...if that section ends up "twisted" the rest of the cabinet will become "twisted" also.  LOL!

 

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5 minutes ago, HDBRbuilder said:

Wherever you wil have overlapping panels, such as the top of the cabinet to the sides, be sure to cut the top, for example, a little bit "proud" on its left and right so that it has a very fine "lip" overlap when installed...then you just putty-up any voids in the plys on the sides and sand it flush to the sides.  You can do the same for where the side panels meet the speaker "woofer door" or "bottom" panel...let the sides be a bit proud at the bottom edge and just sand them flush after assembly. 

 

Tolerances are 1/64" or less...with emphasis on the "LESS" wherever possible.   This is ESPECIALLY important for al the pieces involved in the woofer horn section due to the need to eliminate any possibility of "air leaks" from the "doghouse" section.  You want all the sonic energy going through the compression slot and firing into the bifurcated horn-pathway lenses.  Energy lost to "air leaks" from the doghouse will be noticeable, for more than one reason....they will be audible, also!  It is also important because ..elimination of "air leaks" helps to reduce the excursion length at higher volumes...so that your woofer drivers won't be as readily capable of slamming.  When the cone goes outward, the vacuum effect behind it in the doghouse reduces its outward excursion...and vice versa...when the cone is moving rearward, the air overpressure inside the doghouse does the same thing...reduces the rearward excursion length.

 

If you are good at "splitting 1/32" when cutting you will be good to go...anything not cut "square" will create unique problems when assembly begins....have you ever seen a LaScala with a "twisted" bass bin section of the cabinet??...if that section ends up "twisted" the rest of the cabinet will become "twisted" also.  LOL!

 

Whoa, seems like a good idea I left the task to local woodworking atelier (with speaker building skills). They will be building a few for me, but before they do they want to build a prototype to test how it holds out. This will cost me a few extra euros, but as you say it's worth to get a decently build bin! I'll pass your info along so they know what to focus on. It's to good to know they also the right tools like specialised saw tables for the tricky angles. 

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" I think I kind a misunderstood :s You used the LaScala bins in combo with the complete MCM 1900 array? Or with LaScalas instead of the MWM bins? And if you mean mids, you mean a different set of drivers as the K401 horns? Like a MSSM?  Also what are the specs on those MCM Piezo arrays? Cant seem to find any info on them. "

 

The rig was configured differently for each different space.

 

In one huge indoor space (an old grocery store) I used two blocks of four bass cabinets bi-amped at 500hz to two blocks of K400 with the MCM tweeter bins, it souded much better than I expected as all 8 bass cabinets (wired as a 2Ω load, hooked to the 4Ω tap on the MC2120) were on one channel of the MC2120, with all 4 of the K400 (wired as an 8Ω load, hooked to the 8Ω tap on the MC2120) and the two MCM tweeters on the other channel.

 

I also had a pair of stock Industrial with the black fiberglass and the aluminum trim, mainly used for side-fill monitors on large stages.

 

klipsch-mcm-1900-pa-cinema-theatre-6.jpg

 

These have an autoformer (and a crossover) in them to match the high impedance piezo tweeters, I bought a 100 piece case of the Motorola KSN1016 around 1978.

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8 hours ago, djk said:

" I think I kind a misunderstood :s You used the LaScala bins in combo with the complete MCM 1900 array? Or with LaScalas instead of the MWM bins? And if you mean mids, you mean a different set of drivers as the K401 horns? Like a MSSM?  Also what are the specs on those MCM Piezo arrays? Cant seem to find any info on them. "

 

The rig was configured differently for each different space.

 

In one huge indoor space (an old grocery store) I used two blocks of four bass cabinets bi-amped at 500hz to two blocks of K400 with the MCM tweeter bins, it souded much better than I expected as all 8 bass cabinets (wired as a 2Ω load, hooked to the 4Ω tap on the MC2120) were on one channel of the MC2120, with all 4 of the K400 (wired as an 8Ω load, hooked to the 8Ω tap on the MC2120) and the two MCM tweeters on the other channel.

 

I also had a pair of stock Industrial with the black fiberglass and the aluminum trim, mainly used for side-fill monitors on large stages.

 

klipsch-mcm-1900-pa-cinema-theatre-6.jpg

 

These have an autoformer (and a crossover) in them to match the high impedance piezo tweeters, I bought a 100 piece case of the Motorola KSN1016 around 1978.

Could be that it is normal practice in this kind of situations, but did you use a mono signal? And only a 2x120W 8ohm amp for everything? Awesome!

 

What about  those tweeters. Does it matter how the curve goes? Is  the dispersion wide enough to put them vertical (with the tweeters themself horizontal) Or would a more horizontal placement/curve be better suited when only using 3 horns /side? Will have to make my own flightcase like that, beautifull example though, thanks! 

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17 hours ago, Droogne said:

Whoa, seems like a good idea I left the task to local woodworking atelier (with speaker building skills). They will be building a few for me, but before they do they want to build a prototype to test how it holds out. This will cost me a few extra euros, but as you say it's worth to get a decently build bin! I'll pass your info along so they know what to focus on. It's to good to know they also the right tools like specialised saw tables for the tricky angles. 

Whomever is building these for you needs to keep in mind that conversion from U.S. dimensions to metric dimensions can be a problem, especially for the High Frequency motorboard where the tweeter and mid-range horns are mounted...there is not much "wiggle" space for the horn lens mounting flanges on those U.S. dimensions, so they have to be careful when routing out the holes for those so that the flanges will not be forced to overlap each other due to the holes for the horns being too close together...among other problems which CAN occur when using metric dimensional conversions.  REALISTICALLY, they SHOULD have the horns themselves to ensure the accuracy of their metric conversions from USA specs will suffice for mounting what needs to be mounted, prior to making any cuts/holes.

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8 minutes ago, HDBRbuilder said:

Whomever is building these for you needs to keep in mind that conversion from U.S. dimensions to metric dimensions can be a problem, especially for the High Frequency motorboard where the tweeter and mid-range horns are mounted...there is not much "wiggle" space for the horn lens mounting flanges on those U.S. dimensions, so they have to be careful when routing out the holes for those so that the flanges will not be forced to overlap each other due to the holes for the horns being too close together...among other problems which CAN occur when using metric dimensional conversions.  REALISTICALLY, they SHOULD have the horns themselves to ensure the accuracy of their metric conversions from USA specs will suffice for mounting what needs to be mounted, prior to making any cuts/holes.

The top bins are for later, if I even have them made. I'm doing a separate bin setup like the LS II. I have a LSII sitting in box at my home at the moment, which I'm hoping to sell for a fair price so I can finance this project. For now the builders can use it to model the clones of.  By using separate bins  I can easily stack them (I do have to figure out how to place the inputs on the back instead of ontop of the bins). 

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"Could be that it is normal practice in this kind of situations, but did you use a mono signal?"

 

Yes.

 

"And only a 2x120W 8ohm amp for everything? Awesome!"

 

The MC2120 has a 600VA transformer, and by driving the load one tap higher it can play as loud as a 250W/CH amplifier.

 

"What about  those tweeters. Does it matter how the curve goes?"

Yes

 

"Is  the dispersion wide enough to put them vertical (with the tweeters themself horizontal)"

 

They need to stand up (as shown in the picture)

 

"Or would a more horizontal placement/curve be better suited when only using 3 horns /side? Will have to make my own flightcase like that, beautifull example though, thanks! "

 

The stack must be vertical.

 

I also used the KSN 1025 (the 1.8Khz 2"x6" version) in stacks of three.

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17 minutes ago, djk said:

"Could be that it is normal practice in this kind of situations, but did you use a mono signal?"

 

Yes.

 

"And only a 2x120W 8ohm amp for everything? Awesome!"

 

The MC2120 has a 600VA transformer, and by driving the load one tap higher it can play as loud as a 250W/CH amplifier.

 

"What about  those tweeters. Does it matter how the curve goes?"

Yes

 

"Is  the dispersion wide enough to put them vertical (with the tweeters themself horizontal)"

 

They need to stand up (as shown in the picture)

 

"Or would a more horizontal placement/curve be better suited when only using 3 horns /side? Will have to make my own flightcase like that, beautifull example though, thanks! "

 

The stack must be vertical.

 

I also used the KSN 1025 (the 1.8Khz 2"x6" version) in stacks of three.

Still, 250/ch is impressive!

 

Is the horizontal dispersion of a tweeter in that kind of horn (or the K77 horn) wide enough? I believe you, just bit surprised. The vertical curve is necessity though? Is there any coupling that you know of? Cause the K77 can't keep up with the bassbins and K55 when driven to their "max", not sure if thats even a problem, but some extra dbs in the tweeter range is surely welcome. 

 

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