Edgar

Thanks, guys. I forwarded your comments to my sister. It's in her hands, now.

I'm pretty well-versed in Klipsch Heritage loudspeakers, but don't know diddly about their newer lineup. This morning I received an email message from my sister -- she wants to buy a center speaker for her husband; needs for me to suggest what would go well with his Chorus main speakers. So I'll throw it out to the forum, and ask for your help. Since she specifically asked about the RC64, I'll assume that she has up to a $1000 budget. Suggestions? Thanks. Greg

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There seems to be more than a few of us here. Interesting. What is it about horn loudspeakers and hot rods that attracts geniuses? Was PWK into hot rods? I was SO good at academics that people expected me to be THAT good at everything. So in situations where I wasn't so good, instead of thinking, "Well, he can't be good at everything," people thought, "Oh, he's being a pain in the @$$ ... again." And I was just barely good enough at the social skills that nobody suspected that there was anything wrong. So in situations where the lack of REAL social skills let me down, instead of thinking, "Oh, he's just a little awkward in social situations," people thought, "Oh, he's being a pain in the @$$ ... again." The problem continues to this day.

Thanks, but, sadly, I left that scene a long, long time ago. When I had time, I never had money. When I had money, I never had time. Greg

Roger, Oh, good, only one of the responses with which you disagreed was mine (#8). I never actually built a 351 Cleveland; the comment about the 2-bolt vs. 4-bolt main strength came from an old magazine article that I'll never be able to find again. I won't argue the point either way since, as you said, aftermarket splayed-4-bolt caps are available anyway. This has been fun. Greg

Nope, the Boss 302 was a Windsor block with 4 bolt mains and Cleveland-style heads: 221-302 Windsor Engine Magic. Greg On edit: That's not a bad thing. The Windsor blocks had a better oiling system than the Cleveland blocks.

Which 10% was inaccurate? Greg

Roger, you'll get a chuckle out of this exchange on rec.audio.tech, from a guy who thought that he was posting to rec.auto.tech: Ford Engine ??. Greg

Named after Edgar Montrose, a fictional character from the Red Green Show who has a propensity for blowing stuff up.

http://www.harman.com/wp/pdf/multsubs.pdf Page 28 summarizes.

Be aware that Orban's filter approximation method matches magnitude superbly well, but ignores phase. See Robert Orban's comments, and responses to them, here. The effects may or may not be audible; I don't know. Greg

Only the ones with tube thingies in them.

Wow, some familiar names from so long ago. I really liked Flip's Stereo. I hung around the Ballwin store a lot. Music for Pleasure was after my time. I remember when Hi Fi Fo Fum moved to a really nice storefront on Manchester Road near Hwy 141. I was just in that neighborhood last month, but Fum wasn't there. (Of course, my father shopped at Fum in Milwaukee, I think, when I was still a child.) And Antech Labs -- I think I bought a Revox turntable from them many years ago. I still have it, but I no longer use it. Pacific Stereo in Crestwood, where they had a back room that housed the "good" stuff -- Infinity Quantum Line Source speakers, SAE electronics, Kenwood KD-500 turntable with Infinity Black Widow tonearm -- cool stuff back then. And I heard my first Klipschorns at Don and Kathy's House of Music somewhere up north ... Florissant? I feel old. Thanks, Greg

Hmmm ... I don't remember a roly poly doctor. Perhaps that was before my time there, too. I remember Wylie Williams, who still shows up occasionally on Audio Circle Forums, and Len Hupp, and a few other faces for which I cannot remember names. Ancient history, I guess. Thanks, Greg

I was going to suggest that you notify the Gateway Audio Society, but I see that you already did. I'm a former St. Louisan; I'd be there if I could. By the way, anybody know what ever happened to the old St. Louis Audio Society? I belonged to that back in the late 1970s. Greg

No, sport bikes are for the testosterone-overdose set. (Disclaimer: I ride a sport bike ... that I purchased new 18 years ago.) The bikes to which you refer are the big V-twins.

Retro electro: http://www.retrothing.com/2008/09/1968-amcs-amazi.html

The DX38 also includes allpass filters that can be used for the same thing, though not quite as flexible because they are low-Q -- designed for phase compensation in multiway Linkwitz-Riley crossovers. Greg

The room reflections take place in the time domain, but the resulting "peak" is in the frequency response. If the room response peak is minimum phase, then a PEQ of the proper frequency, cut, and width can cancel it exactly. (See this article.) A room response dip generally cannot be corrected by EQ, however. Reading through some online articles this morning, I find that there is quite a bit of disagreement as to whether room response anomalies are minimum-phase or nonminimum-phase. (See this article, for example.) I expect that there is some of both in most cases. It is far better to correct the room itself than to try to correct its problems with EQ. But used in moderation, PEQ can help. Greg On EDIT: this article explains it better; "Unlike the entire loudspeakerroom response curve, which cannot be inverted accurately to provide a room equalisation curve because it is non-minimum phase, controlling room modes is more practical because they do exhibit minimum phase behaviour. In addition, while the magnitude esponse of real rooms ie, rooms which do not have perfectly reflecting walls may vary a great deal in different locations in the room, the decay time of a resonance can be measured successfully almost anywhere in the room, and does not vary much with listener location. In addition, the filters you build as a result, which will be designed to control the reverberation time at specific frequencies, will work anywhere in the room too."

Because I'm being anal retentive. In this case it won't matter much. But if the PEQ center frequency was reasonably close to the crossover frequency, it would. This is because many crossovers (such as Linkwitz-Riley) are designed so that the LF and HF sections operate as complimentary pairs. If you EQ only the LF or only the HF, that relationship is destroyed. Greg

Yes, that's what I was asking. Thank you. That's correct. Since you're not sending any significant 90 Hz signal to the HF outputs, adding EQ at 90 Hz only in that channel wouldn't do anything. Ah, now I understand. Sometimes the order of the filters matters, but only sometimes. Basically you never want to have a cut at some frequency followed by a boost at that same frequency. The reason is that the noise floor stays essentially constant, so if you cut the signal level you also reduce the dynamic range. If you then boost the signal level you also boost the noise floor. It's probably not much of a problem with the DX38 filters, though. Again, assuming that they are the filters that I programmed when I worked there, then they are capable of over 138 dB dynamic range. So boost and cut to your heart's content, in any order you want. Understand, though, that it does matter where you put the filters, depending upon whether you're trying to EQ an individual driver or you're trying to do some room EQ. EQ for an individual driver belongs in the output channel (after the crossover) feeding that driver. Room EQ belongs in the main in of both channels with identical parameters, for the reasons that I outlined in my previous message. Hey, I'm an engineer. Look up "engineer" in the dictionary and it says, "see Anal Retentive". Greg

Yes. Tuner is a "line level" input with no EQ, so you can connect a tape deck, CD player, even the output from a computer sound card. No problem. Greg

Which configuration (from chapter 6 of the DX38 manual) are you using? Probably all of the PEQ filters are the same. (If they're still using the ones that I programmed for EV many, many years ago, then they are definitely all the same.) But whether you can use a particular PEQ filter in a particular place depends upon the signal routing. Or perhaps I'm misinterpreting your question. Are you asking whether the EQ to tame a room resonance should go before or after the crossover? The answer to that question is that it should go before the crossover in each channel, with identical parameters in both. This is because a PEQ filter also affects phase, and using different settings in each channel, or in just the lowpass or highpass section of each channel, will cause some weird stereo effects due to the different phase shifts in each path. Also, don't try to notch-out the room resonance exactly by using a very narrow filter. You'll never hit the frequency exactly, and in fact the frequency will change slightly with temperature, humidity, barometric pressure, and other factors. And when a peak and a notch don't align exactly, you'll hear some very unpleasant artifacts. Greg

327/6³ = 327/216 = 1.5138888...