djk
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Posts posted by djk
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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.
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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DBT is the best thing to use on a solid state amplifier.
Most will power up with a 75W incandescent bulb, the MC250 will run on a 60W.
A Hafler DH500 will need a 150W bulb.
Many amps will not behave with a Variac, the Crown DC300A being an example.
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" And moreover, who really cares? "
A guy that buys an old car with original tires will be in the same situation as original caps in his vintage Klipsch speakers.
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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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In the past, I sold Accuphase and Klipsch, they worked well together.
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" Also, would you happen to know what frequency the California can be crossed over at, and how low it goes? . "
50hz~500hz with an EV 15B.
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"Just move the midrange wire on the T2A from 4 to 3 and change the 13uf cap to a 6.8uf.
Another way: move the wire from 4 to 3, and then put a 15 ohm/20 watt resistor in parallel with the driver. Just slide the leads under the screws for negative and positive. This method allows for retaining the 13uF capacitor."
Try this first, if it's too much attenuation, then buy an aftermarket autoformer from Bob Crites (or try the 16Ω L-pad idea).
A simple switch can switch could be used to go between taps #3, and #4 and lift the resistor (in-or-out).
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" Once caps are replaced one cannot claim they are stock and origin to the speaker. :
So once I replace the wiper blades (or any part in my car), it's no longer original (and somehow worth less)?
Prior to 1971 PWK used whatever cheap surplus oil caps he could get his hands on. After that stock was exhausted he went to some cheap Mylar caps. Those were so dreadful he had new oil caps made. Later he moved back to Mylar.
So what is 'stock'?
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" The Selenium looks smoother? :
Different horn.
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" The key is if there are any components in parallel with the drivers, "
Actually, it is the series connection of an inductor and a capacitor that drops to zero ohms at the resonant frequency. Having a parallel load keeps things from melting down.
If you have a cheap electrolytic it will generally explode, if you have a mylar cap the series inductor will generally catch on fire.
In the case of the newer Heresy 1.5 in the club it was the 33µF electrolytic that went up (after the K22E went open).
I had to go in as soon as the club opened, so the strippers would let me do my work.
(Hey, somebody has to fix the stuff)
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You will probably want a sub with those, and they will sound a bit soft on the VHF too (they are vocal monitors).
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Crossovers higher than 6dB will look like a dead short to the amplifier at some frequency if a load is not connected to them.
I had to repair an amplifier for a club that had lost the woofer on a newer Heresy, the network shorted out, and the amplifier blew up.
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" What is the lifetime of these? "
Indeterminate.
The leads on inexpensive film caps are just just smashed into the ends of the caps after coated with a tin paste.
Better caps have soldered leads, and they last longer.
The old oil-filled caps also fail over lead termination issues.
50 years ago, JBL used stacked-film caps with hand soldered teflon insulated copper wire leads, wax potted in sand-filled paper tubes. I have never seen one of those that has failed.
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" Seems trivial to worry about? "
If you read the comments from the knowledgeable here (BEC, others), they point to an ESR of 0.5 as becoming audible.
As a voltage divider 0.5Ω in series with a 6Ω tweeter is about -0.3476dB
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" And is it OK to use a crossover like the Samson S-3-way? "
NO!
The delays in cheap crossovers can only delay the bass, you need a DSP based delay.
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Standard 5% values should be close enough, 1.2µF and 80µF (electrolytic).
Since Parts Express does not have an inexpensive 1.2µF, I would use a 1.0µF with a 0.22µF
https://www.parts-express.com/dayton-audio-dmpc-10-10uf-250v-polypropylene-capacitor--027-410
https://www.parts-express.com/dayton-audio-dffc-022-022uf-400v-by-pass-capacitor--027-454
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Dean is probably right, it's probably there to flatten out the huge impedance peak in the midrange.
Looks like an early 70's network with the mylar caps, I would replace those caps and then see how it sounds.
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Back in the day when I did live sound, I found two K55V would keep up with four LaScala bass cabinets per side.
The five tweeter MCM 1900 units would not keep up outside, they seemed OK inside though.
While I carried twelve LaScala bass cabinets (out of twenty-four that I built), I never used more than four a side.
Four LaScala per side slam pretty good.
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University MA-25 on the K-1000 horn.
Used in the K-Ortho-12 drive group, the SAHF was an $8 upgrade (K-Ortho-12B).
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100W RMS, 400W peak.
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It will need new electrolytic caps, and at some point new outputs and drivers.
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This one frequently gets stuck on 'repeat'.
Had a problem with this one too:
This one had the store owner destroying the (cassette) tape:
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Its called a gouge.
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we don't eat pigs, you don't eat pigs, so why not not eat pigs together ?
4 x K-55M adapter (K-4M): uses?
in Technical/Restorations
Posted
"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.