3 Channel SET User meets SS Sub

[seti]

Here is page two.

[filmboydoug]

Ian, this is really cool. Thanks for posting this. I saved the plans in a file titled "Project Brown Note".

doug

[Daddy Dee]

Seti,

Thanks for posting the plans. The guy sure did a nice job of matching the Belles

One thing I'm wondering, are the woofers sealed as they face eith

other? If I'm understanding, they are wired, "out of phase" so they do

not fire toward each other at the same instant? So the sound would come

through the cones, kind of like a passive radiator? I don't know much

about subs, but I sure haven't ever seen one configured like this. Is

there any direct radiation of sound?

[seti]

filmboydoug,

no problemo i was happy to be able to get the actual docs it was based on and wouldn't have if you hadn't asked me about it.

Dee, If you look to the right it says Gluestrip all four sides so I

guess so and it looks like there is a board that they attach to as well

or I could be seeing it wrong.

You are right they are wired out of phase it took me a minute to

remember that after I hooked them up wrong and it sounded more like a

flatulence machine and less like a subwoofer.

I have it set now for 65hz to 18hz and I have the volume turned down it

fills in nicely now more felt than heard. It blends nicely now with the

Belles but you can tell it's missing if you turn it off. If I turn the

volume up high on the sub on really bassy stuff it will run you out of

the room a little uncomfortable especially Bjorks album Post track 2 or

3. I prefer it turned down to where it blends in.

He said the most important thing is that the volume does not change and

that it would be ok to change the shape but not the volume.

thanks

seti

[sfogg]

"One thing I'm wondering, are the woofers sealed as they face eith other? If I'm understanding, they are wired, "out of phase" so they do not fire toward each other at the same instant?"

They should be sealed to each other and wired out of phase so that the cones are traveling in the same direction to work together. This is compound loading... you do it to decrease the needed enclosure size. If there was only a single woofer in the box for the same tuning the box would need to be roughly twice the size it currently is. Compound loading two woofers like that reduces the needed box side. It can cancel some distortions in the woofers themselves sort of like a PP amp.

" So the sound would come through the cones, kind of like a passive radiator? I don't know much about subs, but I sure haven't ever seen one configured like this. "

Through the backside of the exposed cone to free space and the backside of the interior woofer into the cabinet and out the ports.

Shawn

[Daddy Dee]

Thanks Shawn makes sense. As a way to reduce cab volume, quite clever, too.

Seti, thanks. What you describe sounds like what I was thinking when I

was using a sub with my LaScalas. The sub didn't really have to do

ALOT, but something was missing when it wasn't playing and what it was

doing was completely below the range of the Scalas.

With the frequencies you have dialed in... 65hz to 18.... is this

from electronics in the sub or what you are delivering from the amp?

How is that accomplished?

[sfogg]

Seti,

BTW, if you aren't doing it yet you might try highpassing the Belle's. Since they are limited in the low bass anyway rolling off the signal to your SETs at about the point where the sub is kicking in will in effect save power for you to use elsewhere.

There are numerous ways to do this but a very simple inexpensive way is with a pair of these...

http://audioc.com/accessories1/misc/hipass.htm

Shawn

[seti]

Thanks sfogg I didn't know that very cool.

"With the frequencies you have dialed in... 65hz to 18.... is this from electronics in the sub or what you are delivering from the amp? How is that accomplished?"

I have extra outputs on my Wright pre that I am using to deliver the signal to the sub amp/crossover which is the black box between the Belle and sub. The amp/crossover then has several controls and I can set the Sub anywhere from 200hz down presently 65hz down.

[seti]

"Seti,

BTW, if you aren't doing it yet you might try highpassing the Belle's. Since they are limited in the low bass anyway rolling off the signal to your SETs at about the point where the sub is kicking in will in effect save power for you to use elsewhere.

There are numerous ways to do this but a very simple inexpensive way is with a pair of these...

http://audioc.com/accessories1/misc/hipass.htm

Shawn "

Not a bad idea I will check that out.

I have been putting this system together for what seems like a very long time. My next upgrade is a good CDP but later on I would like some Quad II Forties in addition to my SETs as I can't part with them yet.

Thanks again!

[DrWho]

Here's how your configuration models up...assuming a rear cabinet

volume of 4 cubic feet and that you're using the Peerless XLS 308

(which I believe is their only 12" home subwoofer).

Yellow = Your current configuration (isobarik sealed)

Red = Same cabinet, sealed, but only one driver

Green = Same cabinet, isobarik, but ported: tuned to 21Hz

Blue = Same cabinet, one driver, but ported: tuned to 25Hz

[seti]

DrWho,

Very cool software thank you!

I think that is the driver.

PEERLESS 830500 XLS 12" SUBWOOFER

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=297-608

[DrWho]

It is interesting to note that you get more SPL with one driver instead

of two (not to mention it's cheaper too)....and you get more SPL with

half the amplifier power too. In other words, isobarik configurations

reduce system sensitivity by 6dB.

Looking at your response curve (the yellow plot), it becomes very

apparent why you are having trouble dialing in the subwoofer. Your

current F3 (-3dB point) is at 50Hz, which isn't much if at all lower

than your lascalas. If you want to think of it another way, your

subwoofer has a large peak centered around 80Hz, which makes it hard to

dial in. For example, if you dial in an 80Hz crossover the technically

correct way, then you end up no apparent difference between using the sub or

just running your lascalas. If you dial it in by ear so that you have

more low frequency information (say 40Hz), then 80Hz becomes 6dB too

loud, which will sound boomy and overpowering. You probably ended up

choosing a volume so that 40Hz was -3dB and 80Hz was +3dB. When you

moved to the 65Hz crossover, you have pretty much improved the

situation by 1dB.

Do you have a variable phase setting on your subwoofer? If you

positioned your sub near your mains with an 80Hz crossover, then you

could mis-align the phase setting on the sub so as to partially cancel

any frequencies in the crossover region...essentially EQ'ing the output

of the sub to flatten the 80Hz gradual peak...making the 40Hz material

seem louder. In fact, you could get a flat crossover response and

achieve -3dB @ 40Hz.

Another alternative would be to simply install some ports into your

existing configuration and increase the output of the lower

frequencies. What I suggest you do is get another one of those

subwoofer cabinets built and remove one of the drivers from your old

one and install in the new cabinet (going to the blue response plot).

Then in each cabinet you should install four, 2" diameter ports of 12"

length. This would put 45Hz @ -3dB, which with the phase trick could

result in a flat response. Also note that you have moved the F3 of the

subwoofer down to 23Hz, which is getting you a ton more output (for

free). In the meantime you

have reduced the power needed by the amplifier and have also increased

the overall SPL while also digging lower. If you want, you can just

stick to one subwoofer cabinet ported with one driver in it and not

worry about the phase trick and you will still have huge improvements

in the sound.

I only mention these things because they are free or rather inexpensive to try.

[Hardhead]

Seti--

If you're interested in the technical side of subwoofer placement, you should look here: http://www.harman.com/wp/index.jsp?articleId=131.0 . It's an Excel program that calculates resonance frequencies and null/peak locations for standing waves in your room. Rather than drag that heavy sub everywhere, you can pretty much tell from the program which frequencies of standing waves are a problem and where to put your sub to eliminate at least some of them. The calculator gives you quite a bit of information, and I had to study it at length to understand most of the data, not to mention how to apply it.

Dr. Floyd Toole had written an excellent white paper on sub location that used to be on that web site, but I don't see it now. All I see is one written by someone else that doesn't seem to be that helpful--this guy recommends a minimum of 4(!) subs. Dr. Toole's article said that putting a sub in a corner makes the sub play loudest, but excites the most standing waves. Consequently, putting it where a standing wave has a null (zero pressure = no sound) will cancel that particular wave. If your room has several standing waves whose nulls occur at or very near the same spot, the sub may sound best there.

Have fun with it, if you decide to use it.

[D-MAN]

One thing IMHO subs have a way of making information that wasn't really there to start with become what you might believe is on the recording. This is just a non technical theory of mine though.

And it can easily be debunked by a waterfall or RTA measurement of the source material itself []

[]

I'm not saying there is no information down there but subwoofers have a way of taking the information that is there adding to it and then presenting it in a fat over powering way. I personally think they sound like bunk. Yes I have heard some supposed descent subs before.

Craig

I tend to agree with Craig on this one. You won't really know what is the "real" amount of low-end that is there without special test equipment.

You could torture yourself with this problem every time you hear a new piece of music...

I think most people tend to become enamored with the "thumpiness" of the low end and tend to set it a little to high in volume than what would be considered "real". It should be seamless to the point where you don't realize there is a subwoofer at all. I rarely find that to be the case...

Most of the time, we end up looking around for the subwoofer that we know is there because it "sticks out".

DM

[sfogg]

DM,

"It should be seamless to the point where you don't realize there is a subwoofer at all. "

.... until you turn it off.

The other thing that can cause a sub to stick out is since it goes lower then the mains it may excite room modes that the mains couldn't excite. The room boom will boost some frequencies which will also resonante in the room longer then they should. That makes the sub stick out and it even effects the overall clarity of the system even much higher up in frequency.

That is not to say good integration with sub(s) isn't possible. But it takes work.

Shawn

[seti]

WoW guys thats is a wee bit over my head gonna print it out and read it a couple times.

D-Man,

I know what you mean by sticks out it was like that for a week or so

when I first had it then I slowly turned the crossover and volume down

now it doesn't stick out like it did. I didn't know if I liked it at

first as it was very thumpy but at the correct volume it is very nice.

In fact I find myself walking over to the sub and feeling it to see if

it is actually on which I guess is a good sign. If I decide I don't

like it in the long run I've got a great HT sub.

Thanks everyont for the information and advice.

[DrWho]

I tend to agree with Craig on this one. You

won't really know what is the "real" amount of low-end that is there

without special test equipment.

You could torture yourself with this problem every time you hear a new piece of music...

First off, who cares what the "real amount of low-end" is there if it

increases the enjoyment of the music? I just try to enjoy it for what

it is the first time I play it (aka, "critical ears" off).

Secondly, the bass between recordings is anywhere between +-6dB due to

the nature of studio acoustics and how they have their system dialed in

and how loud they're mixing at. It's the whole process of referencing

the mix and is something that we the end users need some tweakability

for. Though adjusting the subwoofer volume is totally the wrong tool to

use, it definetly is a poor man's solution. It is convenient that most

of the referencing problems that occur with the bass volume start

happening more and more as you get below 100Hz, which ironically is in

the range of the typical subwoofer crossover frequency.

I think most people tend to become enamored with the

"thumpiness" of the low end and tend to set it a little to high

in volume than what would be considered "real". It should be seamless

to the point where you don't realize there is a subwoofer at all. I

rarely find that to be the case...

You presume quite a bit...basically implying that everyone that uses a

subwoofer turns it up too loud. I have an open invitation to anyone

that wants to come visit and demo the difference between subs on and

off (it's just the click of the button). It's amazing how the biggest

difference is an increased quality in the midrange...and of course the

occasional really deep note.

Most of the time, we end up looking around for the subwoofer that we know is there because it "sticks out".

You need to get out more and listen to systems that have done it right.

Then again, no turntable accurately reproduces low frequencies so

perhaps that's the fundamental problem...

Btw, there is no need to mystify the use of measurement tools. In fact,

you can do most of it for free. If you wanted to get more in depth you

could spend $100 for a calibrated mic + mixer to be used with free

software to measure the actual output into your room (RTA). You can

even go one step further and purchase $200 software which will measure

more than you ever wanted to know (ETF). Or you can just use your

bloody ears and dial in things so that they sound pleasant.

Instead of drawing crap random generalities, such discussions would be

far more beneficial when discussing specific situations with all the

variables known.

[NOSValves]

I tend to agree with Craig on this one. You won't really know what is the "real" amount of low-end that is there without special test equipment.

You could torture yourself with this problem every time you hear a new piece of music...

I think most people tend to become enamored with the "thumpiness" of the low end and tend to set it a little to high in volume than what would be considered "real". It should be seamless to the point where you don't realize there is a subwoofer at all. I rarely find that to be the case...

Most of the time, we end up looking around for the subwoofer that we know is there because it "sticks out".

DM

You broke the Klipsch forum cardinal rule here[]

[Erik Mandaville]

Shawn:

"The other thing that can cause a sub to stick out is since it goes lower then the mains it may excite room modes that the mains couldn't excite. The room boom will boost some frequencies which will also resonante in the room longer then they should. That makes the sub stick out and it even effects the overall clarity of the system even much higher up in frequency. "

This is precisely the problem I have had here, even with just the Klipschorns. I've been able to improve it, but I think part of the problem has to do with the fact that the listening room is upstairs on a suspended wooden floor. The effect is probably not unlike the way music boxes were designed to function -- in that they use the table or stand they are on as a sort resonating board to boost their otherwise really small output.

I wonder if tennis balls would help, if I cut them in half and put two under each front corner of the bass bin and one in back? Maybe it would provide some isolation.

I'm curious about the sound of that new amp!

Erik

[filmboydoug]

So would it be the bottom sub that should be wired out of phase?