Sub with towers? (1 Viewer)

[Philip____S]

Hello,
I am currently looking to upgrade my system with new speakers and a pre/pro and amp. I'm really only interested in a good movie experience as I don't really listen to much music and when I do they're mp3s off my laptop run through the system. I'm considering the Kef Q series in one of three configurations and don't know which would be better. Also, I don't don't know if a sub would be needed if I use four towers. I currently have a 5.1 setup with sub and am considering the follow:

2 Q7
2 Q5
1 Q9c
1 SVS 25-31PCi (?)

2 Q7
2 Q1
1 Q9c
1 SVS 25-31PCi (?)

4 Q1
1 Q9c
1 SVS 25-31PCi

If I were to use either of the first two configurations would I want a sub, especially with the second config? I know the sub can go lower than the towers, but from the specs it doesn't appear to go much lower than the Q7. Would it be too boomy with the towers and subs? Any thoughts would be appreciated. Thanks in advance.

 

[Lee-M]

In my opinion, it would not be worthwhile to mate the 25-31PCi with full size towers; for immersive theater sound, you really want nothing less than the 20-39...

To answer the base question (no pun intended); yes, a sub is preferred, even with full-range mains, to relieve the mains of the strain of reproducing the entire range of sound (and most can't...)

 

[Philip____S]

Would I set the front towers to 'small' then? And the rear towers as well if I used them? In this scenario it seems better to buy the bookshelves for the front and rear if I don't use the low frequency capabilities of the towers. Thanks again for your thoughts.

 

[Lee-M]

Ah, there's the conundrum; here you have these awesome tower speakers, capable of reproducing a frequency response cleanly down to (fill-in-the-blank) Hz, and the THX standard recommends depriving them of under-80Hz material. It seems like a waste of what you paid good money for, and you're probably right.

Which is why I love my Anthem AVM20, which allows me to set my mains at small, yet set the crossover for them separately (in my case, at 35 Hz). Bass management is VERY crucial when you have big speakers; not so crucial with bookshelf speakers, with which you would want to set the crossover to your speakers at 80 Hz.

 

[Philip____S]

You bring up a good point about setting crossover frequency. I now another point to consider, do I jump to a higher priced pre/pro to get this feature. It would seem the easy, and cheaper, answer is four bookshelf speakers, though bookshelves and good stands cost nearly the same as towers, more in some cases.

 

[John Chow]

My thoughts...

Definitely go with some kind of tower speaker in the front, be it Q3, Q5, or Q7. Reason? It's good to have extra extension below the crossover point, since the crossover isn't a brick wall, rather a sloping curve. Also, as you mentioned, the cost of Q1+stand ~= Q3, or even greater depending on which kind of stands you're considering. Unless you do go to the trouble of getting a pre/pro with individual xover settings, then you're probably going to want to stick with the 80Hz xover due to the frequency response on the Q9c (50Hz). None of the Qseries speakers are really bottom feeders in terms of bass, so you're going to want a subwoofer regardless. Keep in mind the frequency response curves can sometimes be decpetive. It doesn't really clearly state at which volume the 35Hz was measured at. Plus, those extra 15 or so Hz at the bottom end is really where you start feeling the bass rather than hearing it.

Is there any reason why you're sticking with 5.1? I figure if you're concentrating on 100% HT, then you would consider a 6.1 or 7.1 setup. If you wanted to do 6.1, you could consider using a Q1 for the front center speaker and for the rear center speaker. The cost of the Q9c is almost in line with a pair of Q1s.

The last time I compared the Q3 vs. the Q1, I found the towers to have a 'fuller' sound, I felt they did a better job of filling out the room. It'd probably be best to actually find somewhere to demo the speakers so you can compare 1 against the other.

For the rear speakers, you can definitely make do with just the Q1s. My experience is that there just isn't enough going on in the rears to really require having towers in the back. I think the Q1s would be more than adequate. On the other hand, due to the similarity in cost of Q1+stand, you could consider going with Q3s in the back.

fyi, my previous setup was 5 Q35s and 1 Q95C + SVS 20-39 for my 6.1 setup. I am now down to only 2 Q35s, since I left everything else in the states after I decided to move across the pacific. Before the SVS came, I didn't have a sub, and I can tell you it made all the difference in the world.

 

[Philip____S]

I am actually considering a 7.1 setup but figured I'd stick to asking about a 5.1 setup as the extra two speakers in the back would be identical the the rears and therefore wouldn't really change things much (as far as sub vs. no sub with towers.) Thanks for your thoughts.

 

[Drew Eckhardt]

Although many speakers are reasonable flat at low frequencies, the woofers bottom out at those frequencies when even moderate volumes are played. This is because every time the frequency is cut in half, the woofers must travel 4X as far in a sealed box speaker.

For example, my new speakers are -6dB @ 20Hz. Although they'll hit 117dB @ 80Hz, the woofers are excursion limited to 99dB @ 40Hz, and a paltry 81dB @ 20Hz.

The target for playback is peaks arround 105/115dB at the seats from the main channels and LFE (although 101/111 work for most movies). Those numbers are at the seats, and each doubling of distance from a 1 meter baseline adds 6dB to your output requirements.

Obviously, low frequency speaker output at these volumes is insufficient even without the LFE track... and there you'll need to corner-load the speaker to get your output without requiring ludicrous amplifier power (1000W would do it with an efficient speaker) which will do horrid things to it.

The reason to use larger main speakers is that in order to get smooth integration with a sub-woofer, you need flat response an octave below your cross-over frequency if you're not using speakers and electronics designed to combine acoustic and electrical roll-offs (a THX cross-over that has a -3dB point of 80Hz and 12dB/octave roll off can be combined with a sealed box speaker with the same numbers to produce a 24dB/octave high-pass that's 6dB down at 80Hz)

There's also the issue of distortion. My old speakers are flat into the 30s - but have 10% distortion at those frequencies.

 

[Jaimin]

Doesn't the Sony 4ES and the HK avr525 have bass management capabilities to set different crossovers for the fronts, rears, and center. I know its probably not as detailed as pre/pro setup but it offers some of the capabilites and may be in the price range you are looking for. That is if you still want to stick with towers, which is my personal preference. I am not a 100% about these crossover settings on the receivers I mentioned, so someone please correct me if I am wrong.

 

[LanceJ]

This is kind of a touchy subject but I've got a big mouth so here goes........

Why use such high quality loudspeakers in a system only playing back lossy compressed audio formats (Dolby Digital, DTS & MP3)? For example, I'll admit DTS 5.1 Music Discs can sound excellent, but played through a system such as this & compared to a high-quality CD.....you'll clearly hear the difference.

I.e., I think you'll be wasting a good chunk of these highly-researched speaker's capabilities.

Personally, I would go for the Coda series (if you want to stick with KEF) and save the money for a back surround speaker and/or a better amplifier.

If you don't like the Coda floorstanders (they have a 6.5" "subwoofer"), I would just get stand-mounts from another brand with a good sub since this system is only for movies.

LJ

 

[Philip____S]

Lance,
If you thought Qs were overkill you'll love this (said sarcastically), I went to audition Kefs today and left thinking about Reference 201s for the fronts, a 202c for the center, and Eggs or XQ1s for the rear. Is this stupid of me to spend this kind of money when Eggs or Codas would get the job done, probably. But this is why I didn't buy today. It's easy to get sucked in to the biggest, best thing in the store, but that may not be what is best. I left today thinking I might spend around $10k on speakers when $1k would do. I'll think about it and get probably get something less outrageous, but it's hard to argue against something that sounds this good. What makes it harder is I can afford it, and I say to myself, why not get the best? Why settle for less? The problem with choice is you have it. Only being able to afford Eggs or Codas would be great, because life would be simple. Being able to afford something more expensive makes it complex and makes me irrational (let's face it, $10k for speakers is just plain crazy imo). Anyway, I've got some thinking to do.

 

[LanceJ]

Philip: If you can afford something really special, then hell, go for it. I wrote that advice just in case someone said you HAD to buy such exellent equipment for HT use.

It's like me and Sonic I guess: I may not NEED that banana-cream pie shake after the cheese chili dog & large onion rings, but hey, it's within my price range......

LJ

 

[Philip____S]

It's been quite a while since I've lived in a place where they even had Sonic, and I don't think I ever went to one, but I'm a sucker for chocolate chip cookies and get them every time I go to Subway or Togos. This is usually after eating two large subs. Is it excessive? Yes. Is it satisfying? Only for a short while because I feel terrible an hour later. This is similar to the speakers. They'll sound great at first, but then I'll probably be thinking that I ate (spent) to much and feel lousy about it because maybe they only sounded better in my head because I wanted them too, not because they were actually better. My ideal world be one where Eggs were the same price they are but the same performance as the Refs. Maybe some day.

 

[Dustin B]

Multiple crossovers on pre/pros or receivers have a major draw back. The second of my links explains why.

Quote from a post by Brian Florian of Secrets of Hifi:
http://www.hometheaterforum.com/htfo...537#post739537

The article on Secrets of Hifi spawned from the above quote:
http://www.hometheaterhifi.com/volum...rs-9-2002.html

 

[JohnRice]

Philip, I wouldn't get too caught up in specs. I have Thiel CS 3.6s for my mains and they are very stringently rated flat (+/- 0.5 dB) down to 29 Hz. So, you'd think something like a SVS 25-31 wouldn't make that much difference. Well, it does. I do some work for SVS and have had the powered version of the 25-31 in my system before. There are so many other factors to consider other than the couple specs you list. There is also the benefit of easing up the bass load on the main speakers' amp. I have over 400 wpc going into my Thiels and they still benefit from rolling off the low end. There are usually many benefits to easing off the bass requirements to virtually any speaker.

Anyway, if you are thinking of adding an SVS (which I would recommend) I probably would aim for the 20-39 instead, if you can. As far as how to set the crossover to the sub, play around with it once you have the equopment. that is not something you have to decide ahead of time. I would recommend aiming for a pre/pro that has fairly flexible crossover points. Something below the standard 85 Hz might be nice, but I think going all the way to 35 Hz is far too low to really be practical.

 

[JohnRice]

Oh yeah, and as Dustin said, don't piggyback crossovers. This is called cascading crossovers and can really screw things up. If you use the crossovers in the pre/pro, then you need to bypass any crossover in the sub or its amp.

 

[Dustin B]

I was referring more to the multiple crossover points on most pre/pros and receivers. What happens is that each channel is highpassed at the appropriate frequency. Then for the sub, the LFE and all the other channels are summed and then a low pass is done at the lowest frequency you've selected. So any speaker set to a higher crossover than another will now have a hole in it's frequency response.

 

[RichardHOS]

Using different crossover points for different speakers will cause phase issues when summing the lowpass signal into a common subwoofer.

 

[Zack_R]

Then for the sub, the LFE and all the other channels are summed and then a low pass is done at the lowest frequency you've selected.

I was thinking the LFE on my 4ES receiver was totally separate from crossover. It allows me to select the LFE cut frequency and I think this is applied to the respective channel, regardless of what you have the crossover set to for your speakers.


For example I have my LFE cut (brickwalled) at 90Hz because I am not interested in higher LFE frequencies being sent to the sub. I have my front mains set to a 70Hz crossover point so if it's LFE, the bass is sent to the sub up to 90 Hz and I didn't think the 70 Hz crossover point for the mains was a factor.

 

[John H]

Using different crossover points for different speakers will cause phase issues when summing the lowpass signal into a common subwoofer.

This is outlined in the below article.

"Why not low-pass a copy of each main channel at the various frequencies I want and sum that with the full LFE channel?". Possible, yes, but phase issues become monumental!

Using Multiple Crossover Frequencies

John