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WMcD

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  1. Edit (with big drums) Yel LOW But TON Yel LOW But TON Yel LOW But TON Yel LOW But TON Yel LOW But TON
  2. These graphs show that the distortion remains well below 0.1% as long as the nominal tap value is equal to or less than the load impedance. (Ignore in some of these traces the sawtooth effects, which are due to the Audio Precision's gain-ranging switching.) But when the load impedance is significantly below the tap value, the distortion quickly rises above 0.1%, even at low powers. Read more at https://www.stereophile.com/content/mcintosh-mc275-power-amplifier-measurements#UlTw3WpRfhM11jft.99 Addition by Edit: Ann Landers famously said: "All generalization are false -- including this one." We don't have data on all amps. Applying what Stereophile reports, use of the 4 ohm tap gives the best performance as far as distortion because the actual impedance of the K-horn does go down to about 4 ohms and is certainly below 8 ohms in ranges. This is true of many other Klipsch speakers even though they claim to be "8 ohm compatible." [Get the yellow button, please.] So I'll generalize and recommend that the 4 ohm tap be used with all speakers unless you have some compelling reason to do otherwise.
  3. Let me add that using the 4 ohm tap will reduce the output voltage. But you've got power to spare. It will reduce the amps electrical noise output and reduce distortion (very likely Addition by Edit: See below quote from Stereophile review). It certainly will not hurt anything. My guess is that the power trip circuit is a new addition to the 275 series and thus you might well be a pioneer in this area. It is probably true that other folk using 275's without the power trip circuit have used the 8 ohm tap successfully. Maybe you can see what there is to be seen on a McIntosh forum. Best, WMcD
  4. I would strongly suggest you use the 4 ohm output terminals on the McIntosh. The K-Horn goes down to that impedance in the bass and using 8 ohm or 16 ohm output terminals could very well cause the protection circuit to trip. WMcD
  5. Some nice comments by Gary. But let me side with PWK and his use of 1/2 watt 27k resistors rather than Gary's thought that a higher power rating is a temptation given today's SPL preferences. I"ve done some calculations and concluded that it takes a stereo amplifier rated for 3375 watts to reach the 1/2 watt rating. Please check my calculations. The only part which may be unfamiliar is the analysis that the highest power is delivered into the 27 k resistors in the arms of the Y (on the schematics) is when the stereo amps are operating 180 degrees out of phase. Maybe some sound sources do that 180 degree thing as when we have only surround in old style Dolby. In a more familiar sense: It does create a condition like bridging stereo amps. This results in a voltage of zero at the meeting point where the center channel or mono signal is extracted. In out of phase condition there is no center channel signal to be had. Anyway. Assuming you use the speaker output version of the box the calcs show that you need a stereo amp rated for over 3.375 kilowatts (and outputting all of it) to put the 1/2 watt into the 27k resistors. Further, you'd be putting that 3.375 kW into the speakers. Assuming you use the line output version, the voltage at the RCA jacks must be 116 volts -- an obvious impossibility. In conclusion, PWK was conservative in his choice of 1/2 watt resistors. Addition by edit: I hope Gary is not insulted. That is not my intent at all. WMcD Center Channel Mixer and 27k half watt R.zip
  6. "Way too complicated" ????? PWK, then, was wrong. I don't think so. Edit: I see a possible ambiguity. I should should have typed: "If it is way too complicated and simply using a Y connector works as well, then this would mean PWK was wrong in the design." I didn't mean to indicate a time issue: i.e. that PWK was wrong (then) back in that day. I believe my little rhetorical device is clear though. Any confusion is regretted. WMcD
  7. What you need is a circuit like the one PWK used in his center channel mixing box. PWK need a mono or Right plus Left signal for the center channel and you need a mono or Right plus Left signal for the woofer. [Addition by Edit: You can do some creative thinking by visualizing you sub as a center channel speaker with very good bass and not so good treble!] The Dope from Hope has one schematic where it is shown fed by RCA connectors (line output of the pre-amp) and another schematic where it is shown fed by speaker wires (speaker level output of the power amplifier) . But the circuits are essentially the same in the use of the three resistors [47k from memory]. The device in photo might be similar too. You are correct that it is a bad idea to connect amplifier speaker or line level outputs together in parallel. They wind up fighting each other rather than combining i.e. mixing or adding. It is a different situation when the signals combine through the high value fixed resistors. The signal from the right output does appear at the left output. However, the outputs have enough authority to not be influenced. This is actually the effect of a relatively "low output impedance."
  8. I think it is not just the horn . . . the cost of the driver is probably a big consideration with respect to home units. It is, IMHO, a bit discourteous to ask Roy for the reasoning of Klipsch's choices in business matters or technical matter and I'd never do it. Further, it wouldn't work! So why annoy friends? WMcD
  9. Troubleshooting: Has this particular unit ever been known to work properly? Has it ever been been abused? Can you hook it up to an amp to just play a single channel of unprocessed music and voice for testing? Determine whether the tweeter is working by using a paper towel roll as an improvised stethoscope. WMcD
  10. I'll second the SSD and I've retrofitted some older laptops. Moving over the OS etc is easy except that some utilities will not duplicate proprietary recovery partitions. Maybe making an image solves this. Buy the biggest you can comfortably afford because the units like empty space. I've bought several refurbished and open box units from Best Buy and Microcenter with no problem. These are great ways of saving money. WMcD
  11. I seem to recall that one of our moderators long ago said the Speakerlab plans were good. Also someplace on the forum the Klipsch plans were published but were missing a page. Then I found the missing page with a Google Image search. (Actually I searched for the preceding page figuring the missing one would be nearby.) What I found was the complete set by PWK as posted someplace by Bruce Edgar. If anyone wants to use lumber for the interior all I can say is: Youuullll beeee soooorrryyyy. Smile. Dimensional stability is important for an air seal. That is another reason to build a Jubilee -- the chamber is super simple and with a hatch on each end easy to seal. It seems to me the only non plywood version was the Plexiglas one.
  12. I'll bet the beancounters didn't like the cost of the K-500. HDBR has described how difficult it was to assemble. But still, it was the beauty of the lineup. But maybe the equation that the LSII is like a Belle can be run in reverse. A Belle is like an LSII. Dare I say "Belle II." Now there are CNC machines for cutting and the LSII assembly technique is perfected. The same veneer MDF can be used. The workers assembling the LSII don't have to learn new skills to make a Belle II. The mumps midrange will fit. Crossover might take some work. Goes well with a Jubilee with mumps too. Mumps surround speakers anyone? It is not that farfetched. Smile.
  13. IMHO. If you are absolutely, madly, insanely in love with the oak you could use it for the exposed areas where Klipsch uses veneered ply Actually not that much area all things considered. Won't you need joining? There is no reason to think it is going to sound better BTW. Otherwise the interior pieces really should be ply for the sake of your sanity. It is already fabulously difficult to saw. I'll admit to not knowing how a solid plank will take to the cutting. You should take a look at whatever plans you have and note the widths. No one will ever see these interior pieces. That is what I think.
  14. Roy and his compatriots certainly deserved this review. Paul probably gave him a back pat "Nice Work" from upstairs. WMcD
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