sfogg

DrWho, I posted a number of different measurements on the 44xt at: http://forums.klipsch.com/forums/t/84288.aspx?PageIndex=4 Shawn

"I follow that you may not want tweter and woofer over-lappig butt dont' see that as time alignment!?!?!?!?!?" In all multiway speakers there is always some measure of overlap. In first order crossovers the overlap spans octaves. Time aligning the drivers (either electronically or physically) makes it so that the arrival times from the two drivers are the same to the listener. That makes the overlap in phase to reduce the interference between the two drivers. There are still issues elsewhere in the room which is altering polar response which is also effecting the sound at the listening position. The other way to reduce the effects of interference is to reduce the overlap. For example the crossovers I'm using drop over 30dB in about 1/6 of an octave. This has dramatically lower overlap which reduces interference effects everywhere in the room. With first order crossover there is nearly 5 octaves of music before they drop as far as my crossover does in 1/6 of an octave. "Why not single driver ala open baffel design???" Because that has its own set of trade offs. Dynamic range constraints, typically reduces bandwidth, uneven polar response (beaming up high). But like you said one of the benefits is the removal of that overlap between drivers which gives these a coherence that most multi-way speakers don't have. "so you have indede tested it personaly??? " Changes in audio due to changes in timing between the speakers is pretty easy to hear. If you have a test CD that has pink noise play that through one of your speakers. Move vertically compared to that speaker.. you are basically changing the relative path lengths to your ears. The character of the pink noise will change. How much will depend upon the slope of your crossovers and the physical alignment of your drivers. Shawn

"Here's one I think deserves a serious look at: http://www.greatplainsaudio.com/downloads/390series.pdf" I believe that is basically the Altec 290. From what I have read most cross those over around 4500 or so so you will be more limited in what you use for a tweeter. Shawn

"> in live concert bass and trebel arrive at lisener at slightley diffrent times _____ BUT IT DOESNT' MATTER! and concert venyu is MUCH BIGGER ... . .. . .. so why would it matter in a LR A SOLUTON TO A PROBLEM THAT ISNT'!!!!!!!!!" You misunderstand the problem. In a concert you have dozens of instruments in space playing their notes. Each instrument is playing the entire frequency range of that instrument it is a single reproducer of its music. To keep it simpler with one 2 way speaker you have a tweeter and a woofer trying to reproduce all the music from the concert. In a typical situation the woofer and the tweeter are both trying to reproduce some of the same material. If they are not time aligned with the listener (or crossed very steeply) the two drivers are interfering with each other and causing changes to the waves they are reproducing.... altering the signal from what they should be reproducing. With the path length differences in horns this is*easy* to hear in action if you do a simple test. To get more complex... now consider the same thing occuring between all the drivers in the left speaker and all the drivers in your right speaker. You now have 4 drivers trying to reproduce the sound a single instrument makes in space. This causes many issues... again easy to hear in action with simple tests. To get even more complex.... even if you are time aligned at the listening position unless you are concentric (or very steeply crossed) the response at other points in the room aren't time aligned and it alters the response at those points. You hear this too due to the reflections within your room. Shawn

"This is the key to what this is all about. A lot of these drivers will specify the crossover with an asterisk * footnote. When you read it, it will tell you something like 12 dB / octave minimum filter. This is telling you that it can't handle even moderate low frequency energy without distorting" 44xt 1000hz-20k Hz 320w peak power 160 watts program 80 watts continuos on pink noise ine the range specified 500hz to 20kHz 200w peak 100w program 50w continuous The post about quadrupling throw when you go an octave lower is dead on.The flip side of that is the more efficient the driver is in the first place the smaller its diaphragm movement. Quadrupling the throw of a diaphram that is moving .1mm is a lot easier then quadrupling the throw of a diaphragm moving 1mm. Shawn

Dave, With the 4" diaphragm and its power handling I think it would have no problem at all going to 400hz. This is the Peavey on the K510 with just the CD compensation top end at 10kHz... Scale out to 20kHz... These are linear scaled above so from 10kHz to 20kHz is half the screen. In other words those two notches up high are around 1/10 of an octave wide... very narrow and IME nothing to worry about. The Peavey has a better top end then the Altec 288s I had before it. Shawn

"In the search for possible Drivers for use with the Eliptracs, I have run across a few I think might work well 2-way." I'm still very happy with the Peavey 44Xt run two way with the K510. Shawn

"Panel resonances usual show up as dips in the frequency response, not peaks. They way I conceptualize it is that the acoustical energy that would otherwise be moving the air, is now moving the panel instead..." I guess that depends on where you are measuring. Most any panel resonance test I have seen are measuring the motion of the panel itself, in that situation it looks like a big peak. But if that panel is out of phase with the acoustic output of the speaker then it might show up as a dip elsewhere. The real test of a resonance is to look at the decay. A resonance will have a very long decay relative to the frequencies around it. That is why a resonance down low in the bass can be heard as muddy midrange... you literally are getting sound output when it isn't supposed to be there that is masking other details in the recording. Shawn

" The trick is that it has to be completely removable and leave no marks whatsoever on the stock cabs. " You could do something like what John Allen did in his smaller HPS-4000 speakers which should look familiar.... http://www.hps4000.com/pages/525_.html I think the panel vibration is at a fairly low frequency. When I kick in a high pass on the LaScala's (at 70 or 80hz) it greatly reduces the vibration. Shawn

"It's odd though, why try to reduce a resonance with a filter? You'd be kiling the vibration but also the music at that frequency." The LaScala has a big peak right around there. Reducing that gets rid of some of the congestion/chesty sound it imparts on some material. When I EQed my LaScala's I had a similar PEQ in that area. Shawn

".good to hear comments from someone who has used the large format Atec drivers.....the 288's go to about 15K " More like useable to 10 or 11k IMO with new diaphragms from Great Plains. They were too soft like that as a two way. With the used work hardened diaphramgs that came with the drivers they were barely getting to 5k as I recall and couldn't go under 1000hz or so. Measurements are on the forum somewhere. With the good diaphragms I crossed at 8k to the JBL 2404s. The 902s go much higher, I ran them two way. "the 390's top out at about 6 or 7K" If those are like the 290s I think it is more like 4500 or so. That limits tweeter choices somewhat. "nterested in your comments on the Peaveys.....did you find they had the same quality of sound as the Altec combinations?" The Altecs (and JBLs) are gone, still have the Peaveys. I have been very happy with them. If you want some reading material...... K55 vs 902 http://forums.klipsch.com/forums/p/32246/276842.aspx#276842 288 diaphragms: http://forums.klipsch.com/forums/p/62120/607799.aspx#607799 288 and 902s http://forums.klipsch.com/forums/p/75942/748993.aspx#748993 Peavey measurements in here starting on page 4: http://forums.klipsch.com/forums/t/84288.aspx?PageIndex=1 Shawn

Altec used 902s in commercial theaters at 500hz second order all day every day. They can take it. When I was using the ES600s I had the loading caps removed. The 'problem' with the larger format Altec's is they really limit you to three way operation. I had 288s but they didn't have enough on the top end to run two way. The 902s can. I think the 390s have less top end then the 288s. If you want to go large format check out the Peavey 44xt which is either a 1.6" exit or a 2" exit. With its 4" diaphragm it can easily handle lower crossover points and it has plenty of top end for two way operation. Those on K510s replaced all my Altecs and the JBL 2404s I was using with the 288s. Shawn

What horn are you going to have the 902 on? I ran 902s w/511Bs on my LaScala's using the ALK Universal networks along with the K77. The LaScala's were also high passed at 80hz. 902s handled it fine. Later on I switched to two way using the ES600s which was a great combination. Shawn

Al, You can switch between A,B or X whenever you want. With the QSC it is all done by remote control. You know the identity of A and B, you just don't know which X is. X stays constant for the entire trial so you have the ability to switch back and forth between all three as often as you like. When you have determined if X is A or B you enter that as the answer on the QSC and it moves you on to the next trial. At that point it randomly makes X A or B and then again keeps that constant for the entire trial. "You could definitely hear a clue about what was selected since a relay has a different sound on pull in then on release." That is why A and B have their own relay(s). On any switch you release the currently energized relay(s) then energize the chosen relay. You do this even if you are on A and select A. "I think the "buzz" would still be needed in case the same selection happened twice in a row. " That really is not needed. You just break then make on every selection and the switching is removed from the equation. Shawn

Al, "'Im not sure if you figure the listener should know when the switching action takes place or not. I would think he should know when to take note of changes." The listener has complete control over when the switching occurs. It is totally up to them when and how the switching occurs. For example when I take ABX tests after I iniitally determine what to listen for I never even bother listening to B. I just switch between A and X. If A = X then I answer A, otherwise I answer B. With the QSC ABX box you are the listener can be the only person involved in the test since the box handles randomizing X and running the trials for you as well as keeping score. Shawn

Al, That would switch it but that would also be giving away the identity of X when you make the switch due to the physical sound of the relays switching, or not switching as the case would be. In your wiring say for A you are using the NO side of the relay and for B you are using the NC side. For this trial X = B. The ABX breaks before making when you switch from any input to another. You switch from B to A (NC to NO) and you hear the relays switch and the music switch. You switch from A to B (NO to NC) and you hear the relays switch again and the music switch again. Now you switch from B to X (NC to NC... in other words no voltage to the coils to no voltage to the coils) and there is no relay switching noise and no switch in the music. You just gave away the identity of X without actually listening to anything more then the relays. Conversely if X = A you will always hear a relay switch when you go from B to X AND a DOUBLE switch. One from A to X then a switch again from NC to NO when ABX again makes the coil voltage connection. In that situation you are going from voltage to the coil, to no voltage to the coil then back to voltage to the coil again. Wired in this manor I could identify X 100% of the time no matter what you were testing...even if A and B were identical the differences in switching are a giveaway to the identify of X. To wire it to eliminate these giveaways you would need independent relays for each network. In each networks relay(s) the signal output of the relays would be on the NO side of the relay and wired to each driver. Now for any switch you will hear the same amount of relay switches no mater if you go from A to X or B to X. You will hear a set of relays open and a set of relays close again every switch. The relays no longer an automatic giveaway. Shawn

Al, It would be easy enough to build an add on to the ABX box to let you switch out complete networks. Just use the existing speaker level relays in the ABX box to switch 5v or 12v DC to external relay banks to switch in/out different networks. You would use single pole relays for each side, not double pole. Otherwise you wouldn't be switching the same way on each change and the sound of the relay switching could give away the identity of X. Shawn

"I believe that only a blind A / B switch test where someone else flips the switch is an actual valid test." Actually that isn't a valid test. Single blind can be influenced by the expectations of the person throwing the switch if they know the identity of what is being switched. listen to this.... NOW.... LISTEN TO THIS!!! You want double blind to avoid this. Person throwing the switch doesn't know what they are switching to and can't influence the test. It is also very possible to do these sorts of listening tests yourself and avoiding bias. That is what A/B/X tests are all about. You know the identity of A and B and X is randomly either A or B. Your job is to identify is X is A or B. You do this for a specific number of trials and if you answer correctly enough times (95% confidence level) you 'pass' the test. If you can find one I think you would really like an A/B/X Comparator. QSC made one awhile ago, I have one and it is a GREAT tool. For each trial it randomizes the identity of X. Using a remote control you can switch between A, B or X as often as you like. When you have decided the identity of X you tell it your answer and it moves on to the next trial again randomizing X. It will keep score for up to 25 trials and will automatically tell you the probability when you are done. You can of course extend the trials out over days or weeks if desired but I have never felt the need to do that. It lets you know if you are hearing what you think you are, or if you are fooling yourself. Manual here. Shawn

http://www.prosoundweb.com/article/lsp_documentation_page_drawings_photos_specs_and_more/ If you google Lab Horn Subwoofer you will find loads of info. I am building one of these for use at the school I work at. Shawn

How about a pair of Danley Lab Horn subwoofers? Shawn

Much better way to solve that problem then the way the Patriots solved that problem...... Shawn

"But it's not the only way, and I personally don't think it's a very good way to choose a tweeter. " Neither is just plugging a bunch of tweeters into a speaker and listening without trying to optimize each of them. Did you even try swapping phase to each of the tweeters to see if that better integrated the tweeter or not? A decent tweeter implemented well will sound better then the 'best' tweeter in the world used poorly. If one then optimizes the 'best' tweeter things will change radically. Shawn

"Now, this gives me a good excuse to buy a pair of good headphones that I have been putting off for a long time. Any suggestions under $300?" If you can handle in ear headphones (kind of like the foam ear plugs) Etymotic ER-4S (or maybe ER-4P to use without a headphone amp) are incredible headphones. They block out around 20dB of external noise for all that much more resolution. Some have said it is like having the speaker cables soldered directly to your brain. I think these are around $200 now. If you can still find any for sale the Sennheiser HD580 are incredibly comfortable, great sounding over the headphones that would be under $300 now. They were replaced by the HD600 which I think would be over your budget. These are harder to drive though so you would likely need a headphone amplifier to get the best out of them. Another really nice set of headphones is the Grado SR-60s. These are around $70 and sound very good. A little uncomfortable but if you bend the headband in the center it helps a lot. And if you really want to blow the budget the Koss ESP-950s electrostatic (think Quad ESL or Martin Logan speakers) are superb and include an amp. Of the above I have all of these but the Sennheisers. The Klipsch headphones are supposed to be good too but I haven't heard any of them. A good site for headphone sales and information is: http://www.headphone.com/headphones/ Shawn

"Of course the Room has a LOT to do with it. But I somehow feel that it is not just the room and the recording has a lot to do with it." It is easy to seperate the room from the recording.... listen on headphones. The room does have a large influence on the sound. When you are listening to live music the instruments are producing sounds that interact within the acoustic space they are playing in. If a recording of this is made it is also recording the sound of those instruments interacting within the original acoustic space. If it was a multi-track studio album that acoustic space is typically engineered into the recording. You now play this back in your room. The recording has the original acoustic spaces sound still contained within it. However, you now have your speakers producing sounds within your room and those sounds are interacting within the acoustic space they are playing in. You get conflicting cues from the original hall sound on the recording and your own rooms sound. Shawn

Greg, "It's no different for the person using information based only on technical evaluation, it's still just the end-users ears, still their room, still the other equipment they are using, the music they are listening to, and it's just as likely that something will sound good or not as good. They still will have to taste it first to know if they will like it. " It is different if one uses the technical side of the equation to understand their own tastes. If they understand something like that then technical information from another source may be able to give themselves clues as to how they will interpret the sound. The real progress in audio lately is researching and trying to understanding what technical attributes contribute to the majority of listeners impressions on sound quality. Of course very very few people try and understand this. It is far simpler to just call it all vodoo and magic. The great thing about totally subjective reviews is if one uses enough flowerly prose they don't even have to bother listening to the article in question to write the review. (Said only half jokingly). And it still doesn't change how two people may verbalize the sound completely differently...one mans 'deep soundstage' could be anothers 'recessed midrange.' Shawn