I'm working on my new combined music/HT system and am running into conflicting ideas about the specification of side and rear speakers. I have read all the Toole papers and others like the JBL Cinema design ideas.
Assuming my Mains are 40-20k, high SPL capability, controlled directivity (will be using Earl's WG's) and there will be enough subwoofery to keep up, I pose the following questions to the gallery;
Q1: Dipole, bipole or directional Sides?
Earl has briefly mentioned dipoles as being the preferred option and states Thom Holman does too. However Toole and Lynn Olson seem to suggest identical Sides.
Opinions and experiences and why you made your choices are greatly appreciated. Design examples, whether commercial or DIY would help too.
Q2: Specification of Sides?
Once you have picked your design type, what level of performance do I need to engineer into them? For example, 6dB less max SPL, only need 60-15k etc.
Any other design specs I need to consider?
Q3: Rears - necessary or worthwhile?
I believe these are generally synthesised in the HT processor and not discretely recorded in most soundtracks, so should I make the effort to design and build some?
Again opinions and experiences and why you made your choices are greatly appreciated.
Q4: Rears- specifications?
Same considerations as for Q2.
Usage will be 2 channel music (45%), movies (45%) and multichannel audio (10%) at a guess.
Please don't worry about budget etc at the moment as I can say add rears next year if I need to save for them. Current room is approx 4x7.5x3m WDH, double brick with suspended floors. I use a projector and screen. System will not be used for TV or gaming.
I will not bore you with the details of the rest of the system as I would like to keep the discussion to the speaker design and implementation.
Looking forward to your comments.
Cheers
Brett
Assuming my Mains are 40-20k, high SPL capability, controlled directivity (will be using Earl's WG's) and there will be enough subwoofery to keep up, I pose the following questions to the gallery;
Q1: Dipole, bipole or directional Sides?
Earl has briefly mentioned dipoles as being the preferred option and states Thom Holman does too. However Toole and Lynn Olson seem to suggest identical Sides.
Opinions and experiences and why you made your choices are greatly appreciated. Design examples, whether commercial or DIY would help too.
Q2: Specification of Sides?
Once you have picked your design type, what level of performance do I need to engineer into them? For example, 6dB less max SPL, only need 60-15k etc.
Any other design specs I need to consider?
Q3: Rears - necessary or worthwhile?
I believe these are generally synthesised in the HT processor and not discretely recorded in most soundtracks, so should I make the effort to design and build some?
Again opinions and experiences and why you made your choices are greatly appreciated.
Q4: Rears- specifications?
Same considerations as for Q2.
Usage will be 2 channel music (45%), movies (45%) and multichannel audio (10%) at a guess.
Please don't worry about budget etc at the moment as I can say add rears next year if I need to save for them. Current room is approx 4x7.5x3m WDH, double brick with suspended floors. I use a projector and screen. System will not be used for TV or gaming.
I will not bore you with the details of the rest of the system as I would like to keep the discussion to the speaker design and implementation.
Looking forward to your comments.
Cheers
Brett
I believe if you wade through this fairly comprehensive history lesson you'll understand the complexity of choosing in an 'either/or' sort of way as well as answering your other Qs: http://hometheater.about.com/od/beforeyoubuy/a/surroundsound.htm
GM
GM
Brett,
I can't give you the last word but I can tell you what has worked well for me.
With the 7.1 setup, which I recommend, the side surrounds do not need to create so much of the illusion of space. Therefore, the idea of using a dipole or bipole as the (side) surrounds is not so important as it used to be back in the dolby surround days. The rear surrounds need not be expensive speakers as they are just low level ambience. The side surrounds are also used for ambience much of the time but then need to suddenly reproduce often loud and dynamic sound effects which can be full range or nearly full range in nature.
Standard monopole speakers work well in the new 7.1 setup with the side surrounds needing to be capable of good dynamics and as full range as is practicle for the installation space. An old pair of small mini monitors or inexpensive custom mini speakers will work well for the rears.
My suggestion is to make the side surrounds as large and sensitive and full range as you can without spending too much money or taking up more space than you have for them. The rears can be old used small speakers or an inexpensive small speaker or wall mounted or ceiling mounted set up.
The reason I suggest higher sensitivity speakers for the side surrounds is that it improves the dynamics of sudden sound effects. This is probably of higher importance than absolute sound quality for the side surrounds. Which when playing music is at very low level.
I can't give you the last word but I can tell you what has worked well for me.
With the 7.1 setup, which I recommend, the side surrounds do not need to create so much of the illusion of space. Therefore, the idea of using a dipole or bipole as the (side) surrounds is not so important as it used to be back in the dolby surround days. The rear surrounds need not be expensive speakers as they are just low level ambience. The side surrounds are also used for ambience much of the time but then need to suddenly reproduce often loud and dynamic sound effects which can be full range or nearly full range in nature.
Standard monopole speakers work well in the new 7.1 setup with the side surrounds needing to be capable of good dynamics and as full range as is practicle for the installation space. An old pair of small mini monitors or inexpensive custom mini speakers will work well for the rears.
My suggestion is to make the side surrounds as large and sensitive and full range as you can without spending too much money or taking up more space than you have for them. The rears can be old used small speakers or an inexpensive small speaker or wall mounted or ceiling mounted set up.
The reason I suggest higher sensitivity speakers for the side surrounds is that it improves the dynamics of sudden sound effects. This is probably of higher importance than absolute sound quality for the side surrounds. Which when playing music is at very low level.
I will Second Hezz on making sure the side surrounds are big enough. I built some M&K clone tripoles, and the originals I made were just tooooooo small. There was a strange shrinking of images passing from behind overhead to the front, or vis versa. It's also good that all of the speakers be tonally matched or you will notice a difference. It's most important for the side surround speakers, however I think it has helped for the rear surround too. It really depends on the movie and how the sound mixer used the surround speakers. A lot of movies today are using them for more than just ambiance.
I also agree that Monopoles work fine for the surround speakers today, however, having the diffused drivers, such as in a Tripole design, does add spaciousness to surround effects recorded for ambiance. I've been impressed with what it adds to most of the movies I watch (I added a switch to turn them on and off), however I don't like what they do for music. I don't really like surround music much, especially that which is recorded to sound like you are in the band, but still, they exist, and dipole surrounds mess that up.
I also agree that Monopoles work fine for the surround speakers today, however, having the diffused drivers, such as in a Tripole design, does add spaciousness to surround effects recorded for ambiance. I've been impressed with what it adds to most of the movies I watch (I added a switch to turn them on and off), however I don't like what they do for music. I don't really like surround music much, especially that which is recorded to sound like you are in the band, but still, they exist, and dipole surrounds mess that up.
Thanks, I thought the same basic thing initially. I also thought that sides that as near as practical matched the fronts in FR, SPL and general tonality would have a less obvious aural transition to the side FX for movies and music DVDs.Hezz said:
I have all the drivers for a JBL based WMTMW (2225, 2123, B&C DE250) system which worked well in a rough mockup with whatever amps I had available, and an old prosound active xover. Ported in an almost SBB4 they went to about 40Hz flat and I have enough amps on hand to do 120dB SPL. I might use these for the sides.
I'm also just about to order some AE TD15 and TD10 to make a similar setup in the front. In identical enclosure (but sealed LF) it should get a similar in room response, and I'll cross to subs below that. These would make better mains and 2ch stereo speakers I think.
I also have some old near mint Realistic Mach Ones which should suit as rears, at least until the bug to build something else overcomes me.
Cheers. I mention above my current thinking for the system. However, I also have 8 Eminence B15 and A15 and may try a dipole later for the sides, as once the monopole sides are built, it would only require a few tweaks in the xover to try, and the enclosures are much less complex. If I like these better, i would still have a use for the monopoles elsewhere, so no loss.pjpoes said:
Thanks for your comments guys, it's appreciated.
I would partially agree with Hezz, with one big difference. I see no reason for the surrounds to carry any frequencies carried by the subs especially if the subs are spread around the room. So I would mostly agree with everyhing that he says except that 150 Hz and up is all that I look for in a surround. And I do like the use of rears.
"The reason I suggest higher sensitivity speakers for the side surrounds is that it improves the dynamics of sudden sound effects. "
And I'm not sure about the assumptions behind this statement, but higher sensitivity is always a good thing.
I whole heartedly agree that sound quality in the surrounds is not nearly as big an issue as it is in the mains. There is no "image" to worry about and colloration of the reverb field is quite common. In fact a HF rolloff will give the subjective impression of the sound source being farther away.
"The reason I suggest higher sensitivity speakers for the side surrounds is that it improves the dynamics of sudden sound effects. "
And I'm not sure about the assumptions behind this statement, but higher sensitivity is always a good thing.
I whole heartedly agree that sound quality in the surrounds is not nearly as big an issue as it is in the mains. There is no "image" to worry about and colloration of the reverb field is quite common. In fact a HF rolloff will give the subjective impression of the sound source being farther away.
"I believe these are generally synthesised in the HT processor and not discretely recorded in most soundtracks,..."
I think "synthesized " is going a bit to far, as I believe all of the info comes from the discrete signal.
For instance, in a front-rear pan (or side, depending on speaker location) in a 5-ch system becomes a smoother front-side-rear pan in a 7-ch system, essentially by interpolation.
I also question the strong differentiation made between sides and rears as far as output capability.
While admittedly rare, there are soundtracks that stress sides and/or rears.
I think "synthesized " is going a bit to far, as I believe all of the info comes from the discrete signal.
For instance, in a front-rear pan (or side, depending on speaker location) in a 5-ch system becomes a smoother front-side-rear pan in a 7-ch system, essentially by interpolation.
I also question the strong differentiation made between sides and rears as far as output capability.
While admittedly rare, there are soundtracks that stress sides and/or rears.
Brett,
Do your "mains" include the centre speaker? I would presume it is identical to the LR speakers.
I had 5.1 before. I never thought that the rear / side speakers were as important. However, I found the centre speakers to be very important. Since I didn't use a projector, there was no chance to use the same centre speaker as the LR. So at the end, I ditched the 5.1 and now only used the LR channels.
Regards,
Bill
Do your "mains" include the centre speaker? I would presume it is identical to the LR speakers.
I had 5.1 before. I never thought that the rear / side speakers were as important. However, I found the centre speakers to be very important. Since I didn't use a projector, there was no chance to use the same centre speaker as the LR. So at the end, I ditched the 5.1 and now only used the LR channels.
Regards,
Bill
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This basic design is a common speaker in commercial theaters. I still think there is a big difference in the size of the space we are dealing with, and so I don't know that I buy that the monopole is the best option. However, given the newer high def movies using full range surround channels, something like this might just make more sense.
Anyone looking for about the best bargain in theater speakers for cheap, Krix are amazingly inexpensive given what they are. Not saying they are all that good, just very cheap. My experience with Krix in the past though has been that they make a very high value item, with well built enclosures, decent crossovers, and good drivers. The item I showed is something like 160 dollars. Even their two-ways aren't more than 250 dollars each.
Cheers Earl. I have a ton of good drivers and space is not an issue so I'd rather go big and never run into any output capacity issues from the sides and to a leasser extent the rears.gedlee said:
+1.gedlee said:
I had thought about this and plan to experiment with the HF rolloff.gedlee said:
As mentioned above, I have a lot of high efficiency, high output drivers and don't mind going big for the sides, and the rears. In the current room they will be overkill, but my home (where I'm not living for study and work reasons) is a very large open space so I'm designing with that in mind. Probably a lot of overkill for the current room.noah katz said:
Ultimately I never want to run out of capacity in the system, no matter the soundtrack's qualities. I find it spoils the illusion, especially if the plot and the rest of it are up to snuff.
Hi Bill,HiFiNutNut said:
I'll be using a phantom centre, at least for the next couple of years. I don't need a listening position bigger than 2 people wide, and I find with excellent LR it didn't make a difference for me.
I have a pair of Krix that use a Beyma 8" dual cone that looks like the one in the pic, but the cab looks more like a typical floorstander. Sounds awful. I want to better what I've heard in every cinema near here. Most suck; only two are any good.pjpoes said:
Besides, I don't have the same floorplan requirements, so don't need to spread over a long axial distance. If a cinema was set up for the same requirements as a living room, I think it would be done a bit differently.
I think that this is pretty true. In a commercial theater one is not at all close to the surrounds, but in my HT, they are right on top of me. This is why I have opted for a less direct sound field, such as along the axis of a dipole, in these highly constrained situations. Using two Nathans on the sides for the surrounds would be like wearing head phones. They would be right in your ears. With the dipole setup surround effecs are still audible, but they sound more distant, not right on top of you. More like a commercial theater or the mixing stage.
noah katz said:
Right, this DD FAQ is quite informative on the basics of surround sound, requirements, etc.: http://www.dolby.com/uploadedFiles/...DFAQ.pdf
GM
What I've been doing that seemed to work best for me for sides and rears (though my current living room is only 5.1 due to placement constraints, in my previous home I had rears) is a monopole mounted high and firing upwards.
(I can't/won't mount speakers on the ceiling here, though I like Dr. Geddes' two-drivers-in-a-tube idea and can see doing that in a future residence.)
I agree that quality of the speakers is not that important. In my old 7.1 setup I was expecting a big jump in sound quality when I upgraded my surround side and back speakers from KEF Q-Compact bookshelf speakers to speakers I built around the 8" dual concentric driver from Tannoy's System 800 monitor. After all, as front speakers, the 8" Tannoy-based speakers were clearly and in every way superior to the 5.25" coincident KEFs, and one would expect them to better match the 12" Tannoy dual concentrics I run for LCR than other speakers would. As side and rear surrounds, I honestly wonder if I'd even be able to tell a difference between the two if I didn't know which were hooked up. If I had to do it over, I'd probably use a simple 7" Peerless HDS or similar woofer firing up. Would be much cheaper, that's for sure!
(I can't/won't mount speakers on the ceiling here, though I like Dr. Geddes' two-drivers-in-a-tube idea and can see doing that in a future residence.)
I agree that quality of the speakers is not that important. In my old 7.1 setup I was expecting a big jump in sound quality when I upgraded my surround side and back speakers from KEF Q-Compact bookshelf speakers to speakers I built around the 8" dual concentric driver from Tannoy's System 800 monitor. After all, as front speakers, the 8" Tannoy-based speakers were clearly and in every way superior to the 5.25" coincident KEFs, and one would expect them to better match the 12" Tannoy dual concentrics I run for LCR than other speakers would. As side and rear surrounds, I honestly wonder if I'd even be able to tell a difference between the two if I didn't know which were hooked up. If I had to do it over, I'd probably use a simple 7" Peerless HDS or similar woofer firing up. Would be much cheaper, that's for sure!
Listen guys there is a big difference between what was speced in the format, and what was actually being recorded. While the format allowed for full range surrounds, they were almost always utilized as bandwidth limited channels for the purpose of space saving and further compression. Just look at the response spectrum graphs from movies, which I've seen numerous posts for, that show this phenomena. Movies have only recently, because of the larger storage space, begun making common use of 5-7 full range channels, with only rare exceptions.
You also need to keep in mind that the sound engineer will place bass effects discretely into the .5 channel, all the bass management does is remove bass that was recorded into main channels and place it also into that .5 channel output. However, if the sound engineer chooses to do this for you, which they often do, then this won't be so. My issue here is that I believe that sound engineers were more often than not placing the majority of bass into the.5 channel and even the main channels, knowing that most theaters have pretty bandwidth limited surround speakers. It not only worked better for the type of surround speakers used in home theaters, but also helped save space on the dvd, for more extras.
I will see if I can take pictures of the spectrum graphs and post myself, but I have taken the soundtrack from my superbit dvd of Fifth Element, and show you how in both the DD and DTS soundtrakcs there is no energy in the surround channels below 250-300hz during many of the scenes where you would fully expect there to be (ships flying over head, explosions, etc).
You also need to keep in mind that the sound engineer will place bass effects discretely into the .5 channel, all the bass management does is remove bass that was recorded into main channels and place it also into that .5 channel output. However, if the sound engineer chooses to do this for you, which they often do, then this won't be so. My issue here is that I believe that sound engineers were more often than not placing the majority of bass into the.5 channel and even the main channels, knowing that most theaters have pretty bandwidth limited surround speakers. It not only worked better for the type of surround speakers used in home theaters, but also helped save space on the dvd, for more extras.
I will see if I can take pictures of the spectrum graphs and post myself, but I have taken the soundtrack from my superbit dvd of Fifth Element, and show you how in both the DD and DTS soundtrakcs there is no energy in the surround channels below 250-300hz during many of the scenes where you would fully expect there to be (ships flying over head, explosions, etc).
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