djk
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Posts posted by djk
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" They beat the crap out of all of the old units. Just no comparison in clarity and crispness. "
Well spoken for someone that has never heard a 2120 with my cap mods.
Typical price for a working 2120, non-working would go for half.
The MC-252 has a lot of room for improvement, it used polarized electrolytics with no bypass in the direct signal path, and NE4558 opamps (gag me on both).
https://www.hifiengine.com/manual_library/mcintosh/mc252.shtml
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Are you talking about the split in the Kapton former?
Crap-in-the-gap makes noise, cleaning it quiets it down.
Never use compressed air.
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Need someone full time for dusting!
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The LaScala will handle your huge Crown on program material above 100hz.
Use a subwoofer with an electronic crossover and you should be fine.
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I would replace all the small electrolytics on both amps, and check the ripple voltage on the main filter caps at half power into a dummy load.
There are some hard-to-find high-voltage multi-section caps in the 2100.
If you do my simple capacitor upgrade in the 2120 (while replacing all the old electrolytics) it will sound better than 99% of all amps, period.
Caps
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Posted by djk (M) on August 13, 2007 at 19:10:35
In Reply to: RE: Sell it to me ! posted by joeychitwood on August 13, 2007 at 16:38:07:
MC2125 caps
Add one 47µF across each ±42V rail at the main filter caps
Add a 0.01µF~0.1µF film cap in parallel with C239, 240 (little board on the input jacks, very tight for space)
Add a 0.1µF film in parallel with C203, 204 (input coupling cap to impedance buffer)
Add a 0.1µF film in parallel with C207, 208 (output coupling cap from impedance buffer)
Add a 0.1µF film in parallel with C219, 220 (feedback cap)
Add a 0.1µF film in parallel with Q215, 216 (bias transistor)
Add a 0.1µF film in parallel with C305, 306 (±15V regulator outputs)
Add a 0.1µF film in parallel with D304, 305 (reference diodes for regulators)
I cut off all the push on connectors in the power supply and speaker relay and soldered them direct. I soldered a pair of 0.1µF film across the speaker relay contacts and cleaned the relay contacts with a sheet of paper and applied De-oxit.
I sprayed De-oxit on the RCA jacks, cleaned the input sensitivity selector switch (very important), and the edge connectors for the L and R amp boards.
I removed the 10-32 screws on the main filter caps and used De-oxit before replacing.
Do not move the chassis with the bottom off, the glass could crack. Put it on a small piece of carpet to help turn at different angles.
The 47µF are under a lot of stress, I used 100V caps even though they only run at 42V.
Even though this changes no measurable performance specification, it will change the sound more than you can believe.
Jackhammer bass from an amp with a DF of only 14?-
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Posted by djk (M) on August 13, 2007 at 19:10:35
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Replace old foam with new foam gasket tape.
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You will need an electronic crossover, pre-outs, main inputs, and four channels of amplification.
http://assets.klipsch.com/product-specsheets/KPT-JUBILEE535-B-Data-Sheet-v04.pdf
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When not using an electronic crossover it is a good idea to use the same size amp on the top and the bottom.
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Four channels for HF, four for surounds.
Need two of these for four bass cabinets.
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It will receive about -6dB of what the amplifier can put out, about 2W for a 300B amplifier.
A 25W part would be needed for a 100W amplifier.
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Dropping a Heresy mid down one tap makes the power level -12dB, hardly a challenging power level for even a 10W resistor.
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Buy all the caps from Erse, ±5% electrolytics, ±3% Polypropylenes.
http://www.erseaudio.com/Products/NonPolarElectrolyticAll/ANP10C-05-47-0-PB
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Looks like a copy of a Klipsch Shorthorn, or Rebel series loudspeaker.
http://www.klipsch.com/products/rebel-floorstanding-speaker
PWK told me in 1980 that he would deny any knowledge of these.
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" Any speculation why that type cap was chosen? "
Cost.
"The 8 uF black box (wax filled foil?) is next in series, after an inductor and resistor to ground. Just the right size cheap?"
Motor start Mylar cap made by Illinois Capacitor.
http://www.illinoiscapacitor.com/pdf/generated/film_products_detail_80388.pdf
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4µF 5% 250V (mylar)
TI=https://www.tecategroup.com/
Table 2 Letter tolerance code Letter symbol Tolerance of capacitor B +/- 0.10% C +/- 0.25% D +/- 0.5% E +/- 0.5% F +/- 1% G +/- 2% H +/- 3% J +/- 5% K +/- 10% M +/- 20% N +/- 0.05% P +100% ,-0% Z +80%, -20% -
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May just need a tube.
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Move the mid down to tap #3, and either add a 15Ω resistor in parallel with the mid, or change the cap to 6.8µF.
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A 1K resistor works better, and a RMS voltmeter will give more accurate results (a 200mV or better full scale).
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Cornwall 1.5, a interim model with the K77, K52, and K33.
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If you use an electronic crossover and bi-amp a speaker like a Klipsch Cornwall with a 50W amp on the bass and a 10W amp on the mid and hf it will play as loud as a 400W amp through the passive crossover.
The 4:1 benefit for bi-amping is only there when the spectrum is divided ahead of the power amps and when the division point is near the mid point of the spectral distribution of energy.On a voltage basis the division occurs around 250hz.This must be weighted by the peak to average ratio so that the equal energy point for above and below the crossover is about 500hz.This is also affected by the slope of the crossover.For the example of the Klipsch Cornwall it has a 600hz crossover point.If the drivers were the same efficency then 50W + 50W would = 200W through the passive crossover.In reality the HF is 10dB more efficent than the LF so we only need 50W + 5W to = 200W.If the HF remains undistorted it will mask distortion from the LF amp driven slightly into clipping.
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Klipsch recommended the K44 over the K43 for a high powered alternative to the K33.
The Qts on the K43 is lower than optimum for the Klipschorn, the Qts of the K44 is higher.
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Check the dimensions, and if they check out you shouldn't have any problems then.
Please let us know how it works out.
Diaphragm...
in Technical/Restorations
Posted
Masking tape folded into a triangle, sticky-side-out.