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JohnA

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Posts posted by JohnA

  1. Your power figures won't be too far off IF you measured the SPL at 1 meter away. If you were 2 meters (10 feet) away, like my speakers are, the speaker is putting out 6 dB more SPL. 6 dB is 4 times the power required.

    Clipping at any frequency adds huge quantities of harmonics (you have to add lots of highs to make a flat-topped, or clipped, wave). Many of those harmonics are in the tweeter's range, adding lots of power that shouldn't be there. So, a bass note at 125 Hz that's clipped can produce enough highs to kill a tweeter that can only absorb 2 watts continous. The tweeters in my La Scalas have been said to have several different power ratings, but 2 watts continuous comes up frequently.

    I'll bet yours is the same. "No clipping Aloud" smile.gif

    John

  2. My La Scalas benefitted HUGELY from Dynamat on the squawker horn. The horn itself has small resonances within its frequency range that color the sound. Dynamat or rope caulk just about kill all of them and the sound is a lot smoother and more relaxed. My favorite electronics dealer said he hated La Scalas until he heard mine and he had to allow they didn't sound like horns.

    John

  3. There are many good add-on phono preamps from Acurus, Aragon, Parasound, and Creek, to name a few, you could use and keep your current preamp. I use an Aragon 47K, but could be happy with the others as well. The 47K is a great phono preamp and has enough gain for moving coil cartridges.

    John

  4. Two Heresy centers won't hurt.

    The center rear is a new inovation. I believe it's called ES and EX, basically using ProLogic to make a rear center out of the 2 rear channels. The disc has to have the encoding for it to work well.

    I like to see an amp that can put out nearly 2x the rating into 4 ohms and I think 100 watts/channel is plenty. I like to see distortion ratings at or just below 0.1%, too low implies too much negative feedback and much more implies too little. I like simple designs, MOSFET output devices, high damping factors (>300) and slewing rates (>100). Knowing that an amp can pass a clean square wave at more than 1 watt is good, showing good power supply, current capacity and wide bandwidth (you won't se this info much).

    Finally, you have to listen to it, because all of the specs in the world won't describe how it interacts with your electronics and speakers. If the amp has a "character" or sound of it's own, other than the ability to tightly control the speaker, I don't like it.

    Boy, that sounds erudite, didn't mean to get that far out.

    John

  5. If you want a lot of seating, La Scalas in all 4 corners, TV in the center of the short wall, 1 Heresy for a center channel, another for center rear, 2 more for side surrounds. Sell the rest of the gear and buy better amps than Adcom. Look hard at an Aragon Soundstage and 8008 amps.

    John

  6. There is NO reason a passive radiator must be different in compliance forward to backward. That some are is a fact of cost and manufacturing. Earthquake passive radiators are unusual in that they are VERY stiff. The earthquake components I have handled have a spider and are almost identical to the active driver, just like every other system.

    The passive radiator is part of a system. The Earthquake passive is so stiff, it could not be used in anything else.

    John

  7. Power is voltage x amperage. Your amp is spec'd at 180 into an 8 ohm resistor. It might do a little more. More than likely its power supply amd cooling capacity are designed for just that and have little "reserve". The protection circuits are designed to prevent exceeding the amperage that equals 180 watts to prevent overheating. Also the speakers probably dip to 6 ohms in the bass, drawing 50% more current at that point than they would at 8 ohms. That is more current than you amp's cooling and power supply can tolerate. Shutdown.

    BTW, 3/4 "throttle" on every amp is well beyond clipping with most sources. 10 to 12 o'clock in normally full output

  8. The K-77 series are T-35As. Some years, and maybe still, they were tested and hand selected for best performance. The K-55-V was made be Atlas and modified for Klipsch. The K-55-M was made by E-V especially for Klipsch. I was told by E-V that it may have been based on the 1824 or 1828, but was modified to meet Klipsch specs. The K-400 Horn is an adaptation of a dsign Mr. Paul got out of another horn designer's trash can. The K-500 and K-700 are shortened versions of the K-400. It was not intended to be a diffraction horn, though I guess it could have some of those properties. The T-35/T-35A/T-35B/K-77/K-77-M are known as diffraction horns and at lower frequencies they are said to behave that way. However in the band Klipsch uses them they are said to disperse like a normal exponential horn.

    I found flush mounting the K-77-Ms in my La Scalas smoothed their sound noticeably. As an experiment, line the opening in the baffle with heavy felt to reduce diffraction. If you like it Klipsch has brackets used on the K-horn you can use to flush mount you tweeters (after enlarging the hole).

    John

  9. Doug, I think you are heading in the correct direction, but most likely there is a point in the bass where the impedance gets too LOW and the amp is asked for too much current. The protection circuit kicks in to prevent heat damage from overcurrent.

    This is a likely situation. Pioneers of that age were not designed with much excess capacity either in the power supply or the heat sinks.

    John

  10. The Type AL xover is probably most of your problem. It is overly complex, unusually designed and does strange things to the response of the individual drivers. It over controls the system. My rear La Scalas had Type ALs and I though they were squawky, ill-defined in the lower mids and had a screech at high levels. I put ALK xovers in them and almost all of that went away. Damping the horns cured the rest. They are smooth and unaccented, now. The Type AA xover with high quality components is a good sounding xover, but it will have to be adjusted a little for your K-55-M squawker. My front La Scalas have modified Type AAs. Other than the Type ALK, I like the Type AA and Type AK-3, best.

    The AlNiCo tweeter IS a little weak in the upper treble and might also be contributing. The newer K-77-M tweeter is smoother and has more output in the upper frequencies.

    John

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