Basic Sub questions

[colterphoto1]

Forgive me for asking a few 'basic' subwoofer quesitons, but particularly in order to assist other members, I would like to poll the group for answers to the following.

1. Subwoofers have their own power and speaker and usually come with a stated MAX decibel rating, not a sensitivity rating like our other speakers. How is one to determine HOW MUCH sub is suitable for a given system. Ie, my system is Cornwalls with Yamaha '130 watt' receiver. Presumably that will play a max of about 126 dB, lets say conservatively 115 dB. SHould I have a sub that will have clean output equal to that?

2. Is there a simpler formula for the newbie planning a new system, such as the sub should cost about as much as 1/2 to 1 x the price of a 'main' L/R speaker, or some such figure?

3. EAR has recently said that subs should not be run consistently at the MAX on it's volume control, that doing so could lead to premature failure. What would be a safe, long-term, vol knob position to use? Seems like this would be a combination of your main speaker's efficiency (since that determines the line level out to your sub), and your sub size-to-mains efficiency ratio of some type. In my example, COrnwalls all around, but only a ksw12 sub, which sounds good , but barely keeps up with the Mighty Cornwalls.

What I'm also getting at here is the question, Is my sub insufficient for the balance in my system and how big/how much wattage should I have on board? My receiver is Yamaha RXV2400, rated at 130 per channel. I'm 5.1 currently.

Thanks,

Michael

[Colin]

Morning!

1. Yes, the subwoofer output should match the output of the loudspeaker, if possible. Otherwise at loud volumes, it will not be loud enough.

2. Since loudspeakers are the only bargain in audio you get the most bang for the buck, it seems to me everything else costs about as much. To be deep enough and powerful enough for big ole horns, the subwoofer will probably cost as much as the mains.

3. The Ear said they should be full power on the setting, that doesnt mean they are always cranking. It also means the volume is set by the receiver.

My experience with first the KSW200, also a 12, and the ill-fated Klipsch LF10 sub-woofer, with its 500-watt amplifier, one active and two passive 10 drivers, was that big ole horns like the my Cornwalls really needed the deeper bass and louder output of the more powerful subwoofer. My classic Klipsch corner Khorns needed something even more powerful (and adjustable lower) than the two of them. That is why I like the SVS tubes so much they go deep.

As for subs, if you study the frequency response of your big ole horns and any intended sub, you will find that only a few very deep or powerful subwoofers, such as the tall SVS tubes, will match the frequency response of big ole horns, IF you want flat and accurate frequency response. If all you want is more punch for movies, then any powerful sub with prodigious output in the 40Hz area will do great. According to the excellent Brain Weatherhead article, Subwoofers Under the Christmas Tree, (December, 2001) the Klipsch KSW is the most economical value in his sample, while the RSW is the only sub with high output in both the 100Hz upper bass and the 30Hz deep bass regions.

[colterphoto1]

Thanks for the quick response Colin, but could you please elaborate?

1. So does this mean that the ideal sub to match my system needs to be able to output 115 db Max?

2. Economically, Sub would cost as much as ONE or TWO mains? (regardless of fact that mine are old used Heritage) Say if I was planning a system with RB5's all round, as my second system will be, sub cost should be about the price of One new RB5 (about $400)

3. I understand that sub follows output of receiver, but is it okay to set sub vol knob at MAX, then crank up the receiver? Without viewing the cone movement, or listening specifically for LF distortion, will I destroy my sub or is there usually an input limiting device, breaker, etc.

Would anyone have a specific recomendation or experience with an ideal sub for my Cornwall setup? I'm about 50% HT/50% music, where I use the sub occasionally. Music is Classic Rock, some classical and jazz. Usual listening about 90 dB, occasionally I crank it waaaay up.

Thanks again,

Michael

[gcoker]

You want to set the sub volume similar to the rest of your

system. Get a good calibration disk that has signals for setting the

sub. I have a feeling cranking the gain (volume) on the sub and

receiver both will make the bass way too pronounced.

[minn_male42]

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On 2/17/2005 8:36:13 AM gcoker wrote:

You want to set the sub volume similar to the rest of your

system. Get a good calibration disk that has signals for setting the

sub. I have a feeling cranking the gain (volume) on the sub and

receiver both will make the bass way too pronounced.

----------------

agreed!

the best sounding sub/main system will be set up so that you cannot tell when the sub takes over from the mains in reproducing the music - seamless presentation....

the best sub sound in the world does not draw attention to itself, but is only noticible when it's not there...

the over-exagerated "boom" like in car subs is not the way to go

[Frzninvt]

This would be my suggestion, Servo baby! Clean, clear, low and loud. No bottoming out with these I can assure you. I run two Velodyne servo 15's they can shake the foundations I kid you not. I run the volume on them between 3-4 with the preamp level at +2db crossed at 60-80Hz.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=3275&item=5752700605&rd=1

There is also an HGS-15 on eBay another good recommendation. Either of these will pick up where the Cornwalls leave off.

[Colin]

Repeat:

I follow Brain Weatherheads lead in the excellent article Subwoofers Under the Christmas Tree, (December, 2001, http://www.hometheaterhifi.com/volume_8_4/subwoofers-12-2001.html). I assign one point for very 10dB above 70SPL of output at a almost deep 25Hz to create a shake value. Then I divide shake value of 4 dozen subwoofers by their retail price to get their shake value price/performance ratio: the most 25Hz bang for the least buck.

Of two dozen subwoofers rated in order of value, the top five subwoofers with the most 25Hz bang for the least bucks are: SVS 20-39 ($599), Dayton Titanic III 15" kit ($688), used Klipsch LF10 ($550), Velodyne CHT-15 ($599) and Atlantic Tech T70.1PBM ($425), with 82.2dB output (louder than a voice, but not really LOUD! Then the PSB Subsonic 5i ($449, http://www.enjoythemusic.com/magazine/equipment/0604/psbsubsonic5i.htm).

[Olorin]

Michael,

A long time ago I heard an adage expressed that went something like this -- "A subwoofer should be noticed by its absence, not by its presence." You can decide for yourself if that's a reasonable rule to follow.

Since you're talking about 5.1, let's talk principally about home theater use. It seems to me that if you want to treat yourself to everything on the soundtrack, you want balance from the top of the frequency scale to the bottom. The logical conclusion, then, is that your sub needs to keep up with your mains in terms of total output.

You know that room gain and other room effects are going to change the response curve for your sub. In my opinion this renders anechoic and other semi-theoretical (for lack of a better term) measurements somewhat moot.

If I were in your shoes I'd be looking a smooth curve from somewhere below 20 Hz to about 60 Hz to go with those Cornwalls. The output at 25 Hz, absent other information, doesn't say much about a sub's real performance.

You may ask, "Why below 20 Hz? We can't here it anyway." A surprising number of DVDs have a fair amount of infrasonic information. You can't hear it, but you can sure feel it, and having it there changes your experience considerably. The helicopter blades in "Black Hawk Down" whump-whump-whump at about 14 Hz. Sauron's Fall in the opening to "Fellowship of the Rings" rumbles all the way down to 10 Hz. There is a tactile difference between subs that can render that data and subs that can not.

A pair of the 16 Hz SVS tubes might be to your liking, or another of their big subs. Klipsch's THX subs would do nicely. I don't know about the Velo's, but Frzn's experience is certainly positive.

Getting outside the box would be an infinite baffle setup. Four Ascendant Audio Atlas drivers models out with 113 db @ 20 Hz, 103 @ 10, and it does it with 240W total input power. Total cost inclusing EQ and measurement gear would come in under $1500, perhaps less than $1200.

In the end, you have to try some out and see what you like. Theory is wonderful and all, but you know the other adage. In theory, practice and theory are the same. In practice, they are not.

[meuge]

1. The more the merrier. It's always better to overdo it with a sub then underdo it, because you can always turn it down to match your system. My 15" Dayton is certainly too large and too powerful for my little room with RF-3IIs, but because it's such overkill, it doesn't need to move the driver much to satisfy my bass needs, which means less distortion.

2. All subs are different, but 1.25-1.5X the price of one of the mains sounds like a logical number. For example, RF-3IIs w. RW-12 or Dayton, RF-7s w. RSW-12, etc... Of course, based on the size of your room, your needs may be different.

[colterphoto1]

Okay, lets say I like the idea of a Dayton DIY sub kit. Are they as stable and musical as popular name brands?

I'm an ex-home remodeler with good carpentry skills and I know which end of the soldering iron to hold. Could I assemble one of these Dayton kits?

Would you recommend one to go with my Corns? I'm thinking 250 watts in to a 15".

Or I have the Crown Microtech 1200 and an 18" JBL 4645B cabinet. Takes up a lot of acreage, but it's a serious low end cabinet. It s listed as 25Hz tuning frequency, 8 ft3 enclosure, 2242H 18" LF driver, 40-100Hz 97db/w/meter, and with no eq is -3 at 35Hz, with eq will do 22Hz at -3. I'm going to rev this system up this Saturday while DrWho is here to see what the good Dr. thinks. He is engineering his own JBL, so it should be a lively discussion.

The brochure states "The 4645B is ideal for low=-frequency augmentation of either analog or digital sountracks in motions picture theatres and for general sound reinforcement applications. whaddya think?

Michael

[Scp53]

1. i think ideally you should have a sub that can produce roughly the same spl as the mains. but depending on how high of levels you listen to can also determine this. some members on here have klipsch heritage and never go beyond 100db. there for they really dont need a sub that can hit the peak spl of the mains because they never drive them that hard.

2. i dont really think there is a figure for this. you could have either some small audiophile bookshelfs for mains or some huge floorstanders that cost the same(for mains). the sub to match each set of mains is going to be very different in terms of spl needs. do you understand where im going with this? not sure if im confusing or helpful.

3. i think he was refering more to how hard the woofer was actually working. not what the settings are at. imo, setting the gain high wont hurt a thing(maybe create more floornoise) as long as your not over excurting the driver.

and you ask if your sub is insufficient? well what are your mains and surrounds,etc? is it a ref sys or a heritage? your profile says refs but here you act like u got heritage. so ill take it you got heritage. well id go with the recommendations above- look at deep frequency subs from svs. maybe a dayton kit but not sure if the depth is there.

not sure if i helped much.

scp53

edit- i read your above post(after id posted, you beat me) and now see you own corns. so disregard what i said in this post about what speaker you have

[Scp53]

yes, the daytons are very musical subs. i have one and it rocks. id say my sub can hold its own for musicality with subs in the 1k range easily, and it only cost 350(10" mkIII kit).

ask meuge, he has one too. a 15" kit though.

[meuge]

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On 2/17/2005 6:28:30 PM colterphoto1 wrote:

Okay, lets say I like the idea of a Dayton DIY sub kit. Are they as stable and musical as popular name brands?

I'm an ex-home remodeler with good carpentry skills and I know which end of the soldering iron to hold. Could I assemble one of these Dayton kits?

Would you recommend one to go with my Corns? I'm thinking 250 watts in to a 15".

Michael

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Well I haven't seen one post on the web that described the 15" Dayton failing, so I don't think it's a serious issue with these subs. You get a couple of years of warranty, so that's good too. Scp53 is totally right - the sub is very musical in terms of group delay and quick decay.

You really don't need any carpentry or soldering skills to assemble the kit... the only tools you'll need are a straigh and philips screwdrivers, a sharp knife/x-acto, measuring tape and a sharpie (to mark the acoustic foam for cutting), and a 5/32" hex screwdriver. It takes 3-4 hours if you take your time and is very simple to assemble.

Of course if you want to, you can build your own cabinet for the sub and tune it however you want. This gives you control over the sub's appearance as well. But overall, I don't mind the box in its kit form.

I would recommend it. I think it wouldn't have trouble keeping up with the Cornwalls. As far as the amp, the 15" kit comes with a 1000W class G plate amp, so you don't need to worry about that.

For more information, you can contact me directly, as well as check out my detailed review of the kit here:

http://forums.klipsch.com/idealbb/view.asp?topicID=59175

P.S. The kit, which includes the driver, box, amp and acoustic stuffing, is $688 for the mighty 15"-er.

[Colin]

what is the rated and measured oputput for the Daytons at 20 and 25Hz?

[Scp53]

i should note that the whole sub has parts that are made in the usa(nothing foreign). the driver has a 5 year warrenty and the amp a one year(maybe two?). and as a bonus the amp has a parametric eq on it, very useful. and as for amp reliablity, i have been on the pe forums on and off and have not seen any problems with the amp reported. everyone seems to recommend them. my PE amp(250wt) is holding up fine too.

so basically you got a rock solid, musical, high output sub for 688 shipped(do i sound like a salesman?). read meuges review for sure, its really well done.

scp53

[meuge]

I think the 15" is rated to 115dB at 25Hz.

[formica]

When i upgraded from Heresys to Cornwalls I ran into the same problem, as my sub could no longer keep up with to added efficiency. I decided to build my own, which would match both the power and aesthetics of my decorator Cornwalls.

If you want to see a little about it, check out old AV15 sub is ready...

From personal, measured experience... you need a sub which can produce the same SPL levels as your mains. I have measured a maximum in room 20Hz SPL of 119.5db. In testing, the sub will run out of steam at about the same time as the Cornwalls.

My problem now is that this doesn't seem to be enough to keep up with my new Khorns... so I'm going back to the drawing board, with a Infinite Baffle sub using 4 AE-IB15" drivers. Unfortunately that requires a permanent installation, so I have to build my room first.

The minimum commercial sub that I'd see would be like a SVS-PB12-Plus... or a pair of RSW-15s? Not cheap...

Later...

Rob

[colterphoto1]

I'll ask again on this one....

"Would you recommend one to go with my Corns? I'm thinking 250 watts in to a 15".

Or I have the Crown Microtech 1200 and an 18" JBL 4645B cabinet. Almost identical to Cornwall cabinet. Takes up a lot of acreage, but it's a serious low end cabinet. It s listed as 25Hz tuning frequency, 8 ft3 enclosure, 2242H 18" LF driver, 40-100Hz 97db/w/meter, and with no eq is -3 at 35Hz, with eq will do 22Hz at -3. I'm going to rev this system up this Saturday while DrWho is here to see what the good Dr. thinks. He is engineering his own JBL, so it should be a lively discussion.

The brochure states "The 4645B is ideal for low-frequency augmentation of either analog or digital sountracks in motions picture theatres and for general sound reinforcement applications." It's NOT a PA or bass guitar bin.

whaddya think?

Michael

[formica]

Honest opinion?

The JBL sub should easily outperform a KSW.

By design, it's intended to fill in the lower end of some efficient pro speakers, similar to the LaScalas. Therefore it'll have better than average upper bass performance and efficiency, but trades off bass extension to achieve it. If it's a vented enclosure rolling off at 35-40Hz, boosting at about half an octave lower (in the 22Hz region) will quickly push it to it's limits.

You could get better bass extension in a smaller enclosure if you are willing to trade some efficiency for it.

Rob

PS: Cornwalls already do bass much better than LaScalas...

[J.4knee]

"the subwoofer will probably cost as much as the mains."

I don't know squat about subs and really need to learn but that is just downright depressing to think of for a want to be someday K-Horn owner.

Excellent questions Michael, thanks for asking them so concisely.