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Post by ocezam on Sept 1, 2013 12:32:09 GMT -5
LSiM705 ImpressionsWith the recent acquisition of my tube power amps, I’ve been looking for speakers that might be an easier load for them over the next several years. Specifically I wanted better efficiency and an 8 ohm impedance or higher. And of course if I was going to change speakers, I’d want to go up in sound quality, not down. This is hard to do on my budget. After a couple of recent false starts with other speakers, I was prepared to keep my LSi15’s for a while Enter the Polk LSiM705. These speakers have been on my watch list since they came out a few years ago. At $3,000 a pair they’ve been a bit out of my price range. When a recent sale from Polk presented itself, I snapped up a pair! Unboxing:Wow, these puppies are heavy. At 78 lbs these are about 20% heavier than the LSi15s at 66 lbs. All of the internal bracing and separate driver chambers makes for a heavy speaker. They are 1.5 inches taller than my LSi15s and seem to be quite top heavy. The front feet look narrower than those on the LSi15. I’m pretty concerned about these getting knocked over accidentally. I’ve got “outriggers” on order from Sound city: soundocity.com/Steel%20spike%20and%20acorn%20nut%20adjust.htmlI hope they are of good quality as they aren’t inexpensive. Fit and FinishThis is an area that Polk has really outdone itself. These speakers look like hand built custom speakers. Believe me, the pictures do not do them justice. All of the hardware used is top quality. The veneer is flawless and looks painted on. All joints are barely even visible. There are no parallel surfaces in these cabinets and I doubt they are cheap to produce. The grills are held on with hidden magnets. The speakers therefore look great with or without the grills installed. This is a really neat feature. I know that some other high end speakers use this method, but I’ve never owned any and it really works great. The binding posts and plate are higher quality than any I’ve seen on a Polk before. In some other reviews, positive comments have been made about the use of jump wires versus jump bars on the binding posts. This is a step in the right direction. However, I feel the wires and connectors used are slightly cheesy and not up to the overall quality of the rest of the speaker. I replaced mine with some better ones I had laying around. In order to level the speaker, the spikes/feet are adjustable from the top, which is a very convenient feature. The speakers are adjustable where they stand. There’s no need to tilt the speakers to get under them to make adjustments. The adjustment hardware is of high quality and gives the speaker an expensive high tech look. Too bad this area will be modified on my pair to accept the new outriggers I have ordered. It’s pretty dumb to have a speaker this top heavy with such narrow feet. This is one of the very few flaws of these speakers. I’ve read people who’ve raved about the overall looks of the LSiM’s versus the LSi’s. I do not agree. I prefer the LSi15’s aesthetics. I am aware that I am in the minority here. In my opinion the color on the Mahogany models is way too dark. These speakers might as well be black paint. In fact everybody whose seen these so far believes they are black, until I shine a flashlight directly on them. Only then can you barely see these are VERY dark brown. And mine are directly in front of a window! The veneer is also sanded down too smooth IMHO. None of the grain of the wood is visible. Why use real veneer if you can’t even discern it’s authenticity? I also prefer the unique and contemporary shape of the LSi’s. I understand and appreciate the sonic benefits of the LSiM’s curved cabinet, but I don’t think they look as “clean” and they don’t fit my decor quite as well. Please understand the LSim’s are beautiful speakers. The above comments are based on them in my home vs the LSi’s only.
The Sound:In the last few years I’ve had a number of different speakers in my two channel rig for extended listening: Magnepan 1.6
Paradigm Monitor 9 Vandersteen 3 B&W CM9 MartinLogan ElectroMotion ESL Zu Audio Soul Standard Polk LSi15 Of these, I’ve liked the LSi best. They gave me the best balance of clarity/imaging, dynamics and overall value. The LSiM705’s are a great leap forward in every regard. In his Model 7, Richard Vandersteen claims to have produced the world’s first “truly pistonic” drivers, with cones so stiff that they can’t breakup. I can’t speak to that claim, but the model 7 is the best imaging speaker I’ve personally heard. The imaging and clarity of these 705’s approaches that of the Vandersteen Model 7 and easily bests the Model 3 in my opinion. The “aerated polypropylene” cones are said by Polk to provide for a very lightweight and very stiff driver. I believe them. I really can’t say enough concerning the accuracy and precision and clarity of these loudspeakers. Polk has really done their homework on the design. And unlike other highly accurate speakers such as Thiel and Vandersteen, these speakers aren’t bashful. Throw on some Led Zeppelin or Rush, turn up the volume, and they’ll provide an instant party. They have a bigger soundstage than the LSi’s and much bigger than the previously mentioned brands. Lots of audio enthusiasts are aware of the phenomenon of better speakers being less forgiving of poorer recordings. The LSiM705s display this characteristic to an extent. The 705s can sound a little cold when asked to reproduce bad material. This is an unfortunate aspect of hyper accurate speakers. This pair seems to be doing less of this as they get broken in. I mentioned that one of my goals was for a more efficient speaker than my Lsi’s. With my 15’s and these 705’s both being rated at 88db it appears I haven’t accomplished that, and I was prepared to accept that. However, these speakers seem significantly louder that the LSi’s at any given preamp volume setting. I can only guess that my tube amps are happier with the 705’s higher impedance and being operated off the 8 ohm versus 4 ohm taps.
For me these speakers are Keepers. Big time. Truth be told, I could have remained happy with my Lsi’s. When auditioning other speakers, I would at times find a pair that gave me more of a certain aspect of sound quality. Maybe better resolution, or better dynamics. Possibly better sound stage, or better efficiency. But I’ve never found a speaker that provided the overall balance of the LSi’s. At least none I could afford. Until now.
Peace... EDIT: Please disregard the fingerprints on the LSi's!       
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Post by RightinLA on Sept 1, 2013 12:37:04 GMT -5
Nice writeup!. Those new speakers look awesome and from your writeup they sound even better! Well done!
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Post by jt357 on Sept 1, 2013 13:11:15 GMT -5
Congrats, glad you're enjoying the purchase.
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Post by dally on Sept 4, 2013 15:27:46 GMT -5
Great review! I'm glad you're happy with your new LSiM's. I scrolled down and looked at the pics before I read your review and I thought your 705's were piano black. Wow! The midnight mahogany finish is really dark! I also agree with you, I prefer the looks of the LSi line to the LSiM. I was wondering if the voicing of the LSi was similar to the LSiM. Could you use both lines in a multichannel setup? I was thinking of trying the 706c as my center but not sure if it would sound too different. Looking forward to hearing your impressions after you get some more time on your 705's.
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Post by ocezam on Sept 5, 2013 7:53:48 GMT -5
Great review! I'm glad you're happy with your new LSiM's. I scrolled down and looked at the pics before I read your review and I thought your 705's were piano black. Wow! The midnight mahogany finish is really dark! I also agree with you, I prefer the looks of the LSi line to the LSiM. I was wondering if the voicing of the LSi was similar to the LSiM. Could you use both lines in a multichannel setup? I was thinking of trying the 706c as my center but not sure if it would sound too different. Looking forward to hearing your impressions after you get some more time on your 705's. The voicing of the LSiM's versus the LSI series is similar. However the LSiM are much more accurate and actually much more dynamic than the LSi's. The LSiM706C is by all accounts an incredible speaker and is much better resolved than the LSiC. I've considered buying it for my theater. I'm one of those guys that thinks it's much better to have a great center speaker than it is to worry if it comes from the same family of speakers as your other speakers. Your AVR will straighten out any frequency response anomalies and generally the sound when panned across your front stage changes as it goes from speaker to speaker anyway. I'm not alone in this regard, but definitely in the minority. In any event, the LSIM706C is close enough in character with the old LSi series, I wouldn't hesitate to use it that way. Peace ,,, |
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Post by PGT on Sept 5, 2013 8:10:21 GMT -5
I'd concur with that. I've got identical speakers times three across the front on three different setups and all three systems do sound a bit different as it sweeps the center channels of each. I believe it's the mix that the sound engineers do to bump up output from the middle.
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Post by Jim on Sept 5, 2013 8:15:58 GMT -5
Great review! I'm glad you're happy with your new LSiM's. I scrolled down and looked at the pics before I read your review and I thought your 705's were piano black. Wow! The midnight mahogany finish is really dark! I also agree with you, I prefer the looks of the LSi line to the LSiM. I was wondering if the voicing of the LSi was similar to the LSiM. Could you use both lines in a multichannel setup? I was thinking of trying the 706c as my center but not sure if it would sound too different. Looking forward to hearing your impressions after you get some more time on your 705's. The voicing of the LSiM's versus the LSI series is similar. However the LSiM are much more accurate and actually much more dynamic than the LSi's. The LSiM706C is by all accounts an incredible speaker and is much better resolved than the LSiC. I've considered buying it for my theater. I'm one of those guys that thinks it's much better to have a great center speaker than it is to worry if it comes from the same family of speakers as your other speakers. Your AVR will straighten out any frequency response anomalies and generally the sound when panned across your front stage changes as it goes from speaker to speaker anyway. I'm not alone in this regard, but definitely in the minority. In any event, the LSIM706C is close enough in character with the old LSi series, I wouldn't hesitate to use it that way. Peace ,,, Based on a brief conversation I had with Dr. Floyd Toole, when I asked about the importance of timbre matching, he said that it's not that important. Because it's multiple speakers all working on concert, if some of them are a little mismatched, it won't really matter. Personally, I think that if the speakers are somewhat similar, you're perfectly fine. I agree that center channel is very important. |
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KeithL
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Post by KeithL on Sept 5, 2013 9:07:06 GMT -5
I'm afraid I have to disagree rather strongly with that sentiment. Actually, let me clarify that... I do agree that, as long as the only difference between the speakers is frequency response, it probably isn't terribly important (and the room correction in your pre/pro probably will do a decent job of matching the speakers). The problem is that the differences between speakers are often NOT only frequency response. Let's take an extreme example: Let's say we have three front speakers (we'll ignore the surrounds); let's assume that the center is one of our new Stealth 8's (which has a vertically mounted folded ribbon tweeter) and the sides are a pair of our older ERTs (which have cone midranges and dome tweeters). Because the tweeter on the Stealth 8 is a short vertical line source, it has controlled vertical dispersion and very wide, smooth horizontal dispersion (the controlled vertical dispersion helps to minimize interactions with the floor and ceiling, which is usually a good thing). The dispersion on the domes in the ERTs is more equal vertically and horizontally. Now let's run EmoQ, with the microphone sitting on the top of the back of our centrally located listening chair (which is the best place for it). We'll end up with a frequency response that is quite flat at the listening position, and that is equal for all three speakers; and, if something onscreen pans from left to right, and we're sitting at the chosen listening position or near it, the sound will move smoothly with it. But how about if we sit way off to the left side? From there, the sound from the Stealth 8 (the center) will be a bit brighter (because its tweeter has slightly better horizontal dispersion), so our moving sound won't be smooth if it has significant high frequency content (for example, the sound of a helicopter will change as it moves from one side, to the center, to the other side.) Remember, since a helicopter engine sound has both low and high frequencies, part of the sound will move differently than the other part. The same thing would happen if you were sitting on the floor; since the directivity of the three speakers is NOT the same, the EQ that was "perfect" at sitting height will be "off" at floor height. If, instead, all of your speakers were the same, then all of the parts of the helicopter sound would move the same; the image would be much more solid, and its apparent movement much more smooth. It all really depends on your priorities.... If you listen to mostly jazz vocals, which are usually a solo singer in the center channel, probably not moving, then get a great center channel speaker and don't worry about "timbre matching" and all that stuff. BUT, if you're the kind of person who really wants things that pan around the room to do so in a smooth and seamless fashion, then you really should match the timbre and the technology of all your speakers (all dome tweeters, or all Airmotivs, or whatever) or you will notice that the panning and movement between speakers isn't smooth at all. (Remember that we're not just talking abut one speaker being louder than the other; most sounds cover a wide variety of frequencies; if you're listening to a helicopter engine, or a cello, and the primary low notes seem to be coming from one spot, but the upper harmonics seem to be coming from a few feet to the left of that spot, the overall result is that the position will seem blurry and indistinct - and that's the difference between "it's right there - I can just about reach out and touch it" and "it's sort of over to the left there somewhere". For some people, this sort of thing is a big deal - for others, not so much. (Likewise, some people prefer surround speakers that image very well, so they can "place" every sound coming from behind them, while others prefer "diffuse" surrounds, because they feel that stuff in the back sounds more natural when it is less distinct (that is more the "old school" way of looking at it). I won't tell you which is "right" but don't believe anyone who claims that the difference isn't there. The voicing of the LSiM's versus the LSI series is similar. However the LSiM are much more accurate and actually much more dynamic than the LSi's. The LSiM706C is by all accounts an incredible speaker and is much better resolved than the LSiC. I've considered buying it for my theater. I'm one of those guys that thinks it's much better to have a great center speaker than it is to worry if it comes from the same family of speakers as your other speakers. Your AVR will straighten out any frequency response anomalies and generally the sound when panned across your front stage changes as it goes from speaker to speaker anyway. I'm not alone in this regard, but definitely in the minority. In any event, the LSIM706C is close enough in character with the old LSi series, I wouldn't hesitate to use it that way. Peace ,,, Based on a brief conversation I had with Dr. Floyd Toole, when I asked about the importance of timbre matching, he said that it's not that important. Because it's multiple speakers all working on concert, if some of them are a little mismatched, it won't really matter. Personally, I think that if the speakers are somewhat similar, you're perfectly fine. I agree that center channel is very important. |
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KeithL
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Post by KeithL on Sept 5, 2013 9:21:30 GMT -5
Very nice writeup - and nice system. I would just correct one assumption... With tube amps, you want to make sure that your speakers are an impedance that your tube amp can drive well. The output transformer on a tube amp matches the output impedance of the amp to the speaker. While it is true that many tube amps only have 8 ohm output taps, and so have problems with lower impedance speakers, most have multiple output impedance taps. (Generally, you will have poor bass response if the speaker is significantly lower in impedance than the output tap you're connecting it to. Most well-designed tube amps work best when the output tap you choose matches the real impedance of your speakers - but many speakers have impedances that are significantly lower than their "rated impedance", which is why many "8 ohm" speakers sound better on the 4 ohm tap. ) An amplifier with a 4 ohm tap won't have any trouble with a 4 ohm speaker (and an amp with a 2 ohm output tap shouldn't have any problem with speakers whose impedance dips even lower - like Maggies). Likewise, many tube amps are limited in power, and so require very efficient speakers, but there are powerful tube amps out there (our Carver Black Beauties put out over 300 watts each - and they can drive pretty well any speaker; I see what looks like dual pairs of KT88's on yours, so they should have plenty of output power to drive most speakers  ). LSiM705 ImpressionsWith the recent acquisition of my tube power amps, I’ve been looking for speakers that might be an easier load for them over the next several years. Specifically I wanted better efficiency and an 8 ohm impedance or higher. And of course if I was going to change speakers, I’d want to go up in sound quality, not down. This is hard to do on my budget. After a couple of recent false starts with other speakers, I was prepared to keep my LSi15’s for a while Enter the Polk LSiM705. These speakers have been on my watch list since they came out a few years ago. At $3,000 a pair they’ve been a bit out of my price range. When a recent sale from Polk presented itself, I snapped up a pair! Unboxing:Wow, these puppies are heavy. At 78 lbs these are about 20% heavier than the LSi15s at 66 lbs. All of the internal bracing and separate driver chambers makes for a heavy speaker. They are 1.5 inches taller than my LSi15s and seem to be quite top heavy. The front feet look narrower than those on the LSi15. I’m pretty concerned about these getting knocked over accidentally. I’ve got “outriggers” on order from Sound city: soundocity.com/Steel%20spike%20and%20acorn%20nut%20adjust.htmlI hope they are of good quality as they aren’t inexpensive. Fit and FinishThis is an area that Polk has really outdone itself. These speakers look like hand built custom speakers. Believe me, the pictures do not do them justice. All of the hardware used is top quality. The veneer is flawless and looks painted on. All joints are barely even visible. There are no parallel surfaces in these cabinets and I doubt they are cheap to produce. The grills are held on with hidden magnets. The speakers therefore look great with or without the grills installed. This is a really neat feature. I know that some other high end speakers use this method, but I’ve never owned any and it really works great. The binding posts and plate are higher quality than any I’ve seen on a Polk before. In some other reviews, positive comments have been made about the use of jump wires versus jump bars on the binding posts. This is a step in the right direction. However, I feel the wires and connectors used are slightly cheesy and not up to the overall quality of the rest of the speaker. I replaced mine with some better ones I had laying around. In order to level the speaker, the spikes/feet are adjustable from the top, which is a very convenient feature. The speakers are adjustable where they stand. There’s no need to tilt the speakers to get under them to make adjustments. The adjustment hardware is of high quality and gives the speaker an expensive high tech look. Too bad this area will be modified on my pair to accept the new outriggers I have ordered. It’s pretty dumb to have a speaker this top heavy with such narrow feet. This is one of the very few flaws of these speakers. I’ve read people who’ve raved about the overall looks of the LSiM’s versus the LSi’s. I do not agree. I prefer the LSi15’s aesthetics. I am aware that I am in the minority here. In my opinion the color on the Mahogany models is way too dark. These speakers might as well be black paint. In fact everybody whose seen these so far believes they are black, until I shine a flashlight directly on them. Only then can you barely see these are VERY dark brown. And mine are directly in front of a window! The veneer is also sanded down too smooth IMHO. None of the grain of the wood is visible. Why use real veneer if you can’t even discern it’s authenticity? I also prefer the unique and contemporary shape of the LSi’s. I understand and appreciate the sonic benefits of the LSiM’s curved cabinet, but I don’t think they look as “clean” and they don’t fit my decor quite as well. Please understand the LSim’s are beautiful speakers. The above comments are based on them in my home vs the LSi’s only.
The Sound:In the last few years I’ve had a number of different speakers in my two channel rig for extended listening: Magnepan 1.6
Paradigm Monitor 9 Vandersteen 3 B&W CM9 MartinLogan ElectroMotion ESL Zu Audio Soul Standard Polk LSi15 Of these, I’ve liked the LSi best. They gave me the best balance of clarity/imaging, dynamics and overall value. The LSiM705’s are a great leap forward in every regard. In his Model 7, Richard Vandersteen claims to have produced the world’s first “truly pistonic” drivers, with cones so stiff that they can’t breakup. I can’t speak to that claim, but the model 7 is the best imaging speaker I’ve personally heard. The imaging and clarity of these 705’s approaches that of the Vandersteen Model 7 and easily bests the Model 3 in my opinion. The “aerated polypropylene” cones are said by Polk to provide for a very lightweight and very stiff driver. I believe them. I really can’t say enough concerning the accuracy and precision and clarity of these loudspeakers. Polk has really done their homework on the design. And unlike other highly accurate speakers such as Thiel and Vandersteen, these speakers aren’t bashful. Throw on some Led Zeppelin or Rush, turn up the volume, and they’ll provide an instant party. They have a bigger soundstage than the LSi’s and much bigger than the previously mentioned brands. Lots of audio enthusiasts are aware of the phenomenon of better speakers being less forgiving of poorer recordings. The LSiM705s display this characteristic to an extent. The 705s can sound a little cold when asked to reproduce bad material. This is an unfortunate aspect of hyper accurate speakers. This pair seems to be doing less of this as they get broken in. I mentioned that one of my goals was for a more efficient speaker than my Lsi’s. With my 15’s and these 705’s both being rated at 88db it appears I haven’t accomplished that, and I was prepared to accept that. However, these speakers seem significantly louder that the LSi’s at any given preamp volume setting. I can only guess that my tube amps are happier with the 705’s higher impedance and being operated off the 8 ohm versus 4 ohm taps.
For me these speakers are Keepers. Big time. Truth be told, I could have remained happy with my Lsi’s. When auditioning other speakers, I would at times find a pair that gave me more of a certain aspect of sound quality. Maybe better resolution, or better dynamics. Possibly better sound stage, or better efficiency. But I’ve never found a speaker that provided the overall balance of the LSi’s. At least none I could afford. Until now.
Peace... EDIT: Please disregard the fingerprints on the LSi's! |
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Post by Jim on Sept 5, 2013 9:46:48 GMT -5
I'm afraid I have to disagree rather strongly with that sentiment. Actually, let me clarify that... I do agree that, as long as the only difference between the speakers is frequency response, it probably isn't terribly important (and the room correction in your pre/pro probably will do a decent job of matching the speakers). The problem is that the differences between speakers are often NOT only frequency response. Let's take an extreme example: Let's say we have three front speakers (we'll ignore the surrounds); let's assume that the center is one of our new Stealth 8's (which has a vertically mounted folded ribbon tweeter) and the sides are a pair of our older ERTs (which have cone midranges and dome tweeters). Because the tweeter on the Stealth 8 is a short vertical line source, it has controlled vertical dispersion and very wide, smooth horizontal dispersion (the controlled vertical dispersion helps to minimize interactions with the floor and ceiling, which is usually a good thing). The dispersion on the domes in the ERTs is more equal vertically and horizontally. Now let's run EmoQ, with the microphone sitting on the top of the back of our centrally located listening chair (which is the best place for it). We'll end up with a frequency response that is quite flat at the listening position, and that is equal for all three speakers; and, if something onscreen pans from left to right, and we're sitting at the chosen listening position or near it, the sound will move smoothly with it. But how about if we sit way off to the left side? From there, the sound from the Stealth 8 (the center) will be a bit brighter (because its tweeter has slightly better horizontal dispersion), so our moving sound won't be smooth if it has significant high frequency content (for example, the sound of a helicopter will change as it moves from one side, to the center, to the other side.) Remember, since a helicopter engine sound has both low and high frequencies, part of the sound will move differently than the other part. The same thing would happen if you were sitting on the floor; since the directivity of the three speakers is NOT the same, the EQ that was "perfect" at sitting height will be "off" at floor height. If, instead, all of your speakers were the same, then all of the parts of the helicopter sound would move the same; the image would be much more solid, and its apparent movement much more smooth. It all really depends on your priorities.... If you listen to mostly jazz vocals, which are usually a solo singer in the center channel, probably not moving, then get a great center channel speaker and don't worry about "timbre matching" and all that stuff. BUT, if you're the kind of person who really wants things that pan around the room to do so in a smooth and seamless fashion, then you really should match the timbre and the technology of all your speakers (all dome tweeters, or all Airmotivs, or whatever) or you will notice that the panning and movement between speakers isn't smooth at all. (Remember that we're not just talking abut one speaker being louder than the other; most sounds cover a wide variety of frequencies; if you're listening to a helicopter engine, or a cello, and the primary low notes seem to be coming from one spot, but the upper harmonics seem to be coming from a few feet to the left of that spot, the overall result is that the position will seem blurry and indistinct - and that's the difference between "it's right there - I can just about reach out and touch it" and "it's sort of over to the left there somewhere". For some people, this sort of thing is a big deal - for others, not so much. (Likewise, some people prefer surround speakers that image very well, so they can "place" every sound coming from behind them, while others prefer "diffuse" surrounds, because they feel that stuff in the back sounds more natural when it is less distinct (that is more the "old school" way of looking at it). I won't tell you which is "right" but don't believe anyone who claims that the difference isn't there. Based on a brief conversation I had with Dr. Floyd Toole, when I asked about the importance of timbre matching, he said that it's not that important. Because it's multiple speakers all working on concert, if some of them are a little mismatched, it won't really matter. Personally, I think that if the speakers are somewhat similar, you're perfectly fine. I agree that center channel is very important. Keith - I agree with all of your comments. My wording of "a little mismatched" was a poor choice of words, as well as "somewhat similar". My thinking was that the speakers would be similar dispersion, same technology, etc. The difference being the LCR are Polk X and the surrounds are different model, but still Polk Y. I didn't mean to make it sound like it was entirely unimportant. I think Toole's intention was "Don't get obsessed about timbre matching" (IE, if all 7 speakers aren't identical, don't assume it'll be audible). His follow up comment about not timbre matching (@ Cedia Expo) was "You wouldn't do that anyway, right guys?" (Because the audience was installers, integrators, etc). |
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Post by jmilton on Sept 5, 2013 11:01:45 GMT -5
Actually, Dr. Toole says this in his white paper on multichannel sound:
“Timbre matching” of the surround to the L,C.R (front) channels. In my view, this is a dubious feature. Sounds arriving from the sides, or from random incidences will have timbres that differ from sounds arriving from the front because of the head and external ears – see HRTF explanation, p. 16. It is nature at work, and it needs no correction.
...meaning for sides and surrounds, even if all speaker are the same, the timbre will change due to the position of the speakers, as well as the natural shape of the outer ear (pinna). As a reviewer, I have never had issues using different surrounds with my Revel LCR setup. Keeping the LCRs the same is, as Mr. Spock would say, "logical".
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Post by Jim on Sept 5, 2013 11:05:58 GMT -5
Actually, Dr. Toole says this in his white paper on multichannel sound: “Timbre matching” of the surround to the L,C.R (front) channels. In my view, this is a dubious feature. Sounds arriving from the sides, or from random incidences will have timbres that differ from sounds arriving from the front because of the head and external ears – see HRTF explanation, p. 16. It is nature at work, and it needs no correction. I really need to re-read his papers and his book (his book makes WAY more sense when he's explaining it). But then, what about the direct sound? From what I understand, reflected sound is second loudest to direct sound, so if speakers are seriously mismatched, you'll hear it in the pans (in the direct content).... But perhaps, his emphasis is on LCR, where panning is pretty subtle. I don't know! Jmilton - I just saw your last comment. I like that. Perhaps I'm fuzzy on the exact definition of "Timbre matching". |
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Post by Boomzilla on Sept 5, 2013 13:06:18 GMT -5
...Let's take an extreme example: Let's say we have three front speakers (we'll ignore the surrounds); let's assume that the center is one of our new Stealth 8's (which has a vertically mounted folded ribbon tweeter) and the sides are a pair of our older ERTs (which have cone midranges and dome tweeters). Because the tweeter on the Stealth 8 is a short vertical line source, it has controlled vertical dispersion and very wide, smooth horizontal dispersion (the controlled vertical dispersion helps to minimize interactions with the floor and ceiling, which is usually a good thing)... KeithL - May I ask for a clarification? You state that the Stealth 8 tweeter is a "line source." Although this is (technically) true, the height to width ratio prevents it from acting as a very good one. Because the height and width are so close, the tweeter more closely approximates a point source, yes? A true line source: ...has MANY multiples of its width in its height. In fact, the MORE multiples of width to height ratio, the better the source acts as a true "figure 8" radiator with both side and vertical radiation cancellation. Am I misunderstanding this? If my understanding is correct, then how can the Stealth 8 tweeter: ...which looks to have no more than a 2/1 ratio for height to width, be effective as a "line source?" Boomzilla |
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KeithL
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Post by KeithL on Sept 5, 2013 13:26:48 GMT -5
The dispersion of a speaker at any given frequency is determined by the ratio between the wavelength of sound at that frequency and the size of the source. (This is why large midrange cones are more directional at high frequencies, and why tweeters are generally made very small to facilitate good dispersion.) When you have a driver that isn't round, the calculations work the same way, but they are related to that ratio in each dimension independently. A "full line source" would be infinitely long, infinitely narrow, and would have "perfect" horizontal dispersion, and no vertical dispersion - but the effect is still present to a degree in any driver that isn't round. At 10 kHz, the wavelength of sound in air is around one inch. At that frequency, the tweeter in the Stealth 8 is about one wavelength wide and two wavelengths high. Because of this, it actually does have significantly wider dispersion horizontally than vertically at high frequencies. This is true for all monopole (closed back) speakers. An open backed round speaker will generate a 3-dimensional dipole pattern (the "figure 8" is symmetrical); an open backed line source will have a "figure 8" horizontal dispersion pattern. ...Let's take an extreme example: Let's say we have three front speakers (we'll ignore the surrounds); let's assume that the center is one of our new Stealth 8's (which has a vertically mounted folded ribbon tweeter) and the sides are a pair of our older ERTs (which have cone midranges and dome tweeters). Because the tweeter on the Stealth 8 is a short vertical line source, it has controlled vertical dispersion and very wide, smooth horizontal dispersion (the controlled vertical dispersion helps to minimize interactions with the floor and ceiling, which is usually a good thing)... KeithL - May I ask for a clarification? You state that the Stealth 8 tweeter is a "line source." Although this is (technically) true, the height to width ratio prevents it from acting as a very good one. Because the height and width are so close, the tweeter more closely approximates a point source, yes? A true line source: ...has MANY multiples of its width in its height. In fact, the MORE multiples of width to height ratio, the better the source acts as a true "figure 8" radiator with both side and vertical radiation cancellation. Am I misunderstanding this? If my understanding is correct, then how can the Stealth 8 tweeter: ...which looks to have no more than a 2/1 ratio for height to width, be effective as a "line source?" Boomzilla |
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Post by Boomzilla on Sept 5, 2013 13:30:48 GMT -5
Thanks, Keith. The long line source I showed was good down to 150 Hz. so it wasn't the same thing! I'd forgotten about the wavelength affecting the dispersion.
Boomzillah
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Post by ocezam on Sept 6, 2013 7:31:39 GMT -5
I'm afraid I have to disagree rather strongly with that sentiment. I knew my comment would raise a lot of responses. Kinda de-rails my thread but oh well... Sound changes as it pans side to side. As it does front to rear. It happens naturally due to the way we hear and doppler effect. Unless your center channel is very different than the rest of your speakers, I doubt I'd notice a difference, though you might. I would notice a difference if my center channel wasn't as good of a speaker as the rest. Bottom line, I personally do not take multichannel that seriously. To me, Multichannel is movies, stereo is music. Movies are entertaining, music is spiritual. |
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Post by ocezam on Sept 6, 2013 7:37:13 GMT -5
Very nice writeup - and nice system. An amplifier with a 4 ohm tap won't have any trouble with a 4 ohm speaker Yes I know, my amps Do have 4 ohm taps. They had no trouble with the LSi's. They do however sound more powerful with the LSiM's I see what looks like dual pairs of KT88's on yours, so they should have plenty of output power to drive most speakers ). Actually, they are dual pairs of KT120's. Output power is comparable to the Cherry 180, not the 305, unfortunately.  |
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Post by GreenKiwi on Sept 7, 2013 13:34:42 GMT -5
That was a fun review to read, looks like a great system. I do love tube amps.
I'd also agree that with LRC, I've found that if you have speakers that are close/in the same family, it still works quite well. Getting different technologies and sonic signatures between the three and you start to have problems.
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Post by garbulky on Sept 7, 2013 14:53:43 GMT -5
So having had a bit more time with your new polks, do you have any further thoughts? I also have a question about the apparent tilt. Is that for time alignment?
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Post by ocezam on Sept 7, 2013 16:30:54 GMT -5
That was a fun review to read, looks like a great system. I do love tube amps. Thanks. So having had a bit more time with your new polks, do you have any further thoughts? I also have a question about the apparent tilt. Is that for time alignment? I love these speakers. They take me to another place. After more than a year looking and listening, I won't be changing amps or speakers anytime soon. Not sure what you me by "tilt". The baffle is perpendicular to the floor. |
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