Home Theater Systems VS. Music Systems

[mulester7]

Ports don't change anything but room nodes, its not going to get rid or add THD. speed = VooDoo. The speed changes, the note changes. Nuff said.

Sheep

.....and I said earlier that sealed enclosure subs are faster....did I mean that since the element is restricted by no porting requiring more watts to make it move with decent excursion, that it's bound to be more quickly accurate?....WmAx, we need some light shed on this notion of the fastness or slowness of a subwoofer element....you can lay into me hard right off the bat if you wish, I'd say I deserve it....

 

[Buckeyefan 1]

A boomy sub is usually a slow sub. An inexpensive ported sub with an extremely small magnet reacts slower to multiple signals than one with a larger magnet and more available current. In a poorly designed, ported sub with a small magnet and small amp, there is more chance for resonance. In a well designed, enclosed sub with a large magnet and large amp, less chance. It's the design and sum parts of a sub that make it accurate.

It's possible to have too much port in a sub, thus rendering the sub "slow." On the other hand, it's also possible to have too small an amp and too large a box in a sealed enclosure, thus rendering a sub useless. Companies like SVS and Def Tech have found ways to maximize the volume, ports, drivers, and amps to their utmost potential.

In a car installation, volume is severly limited. Enclosed subs are more popular. This usually requires much more amplification, which means more money. In home theater, volume isn't as big an issue. Manufacturers take advantage of this with large boxes, and ported subs. They can use less power to gain equivalent output. There is a give and take there. Larger boxes with ports are usually tuned much lower than sealed, high powered enclosures. SPL's are higher down low, but lower in the mid bass frequencies. Check out pro audio gear, and see where the specs fall compared to dedicated HT subs. Big difference.

 

[MDS]

A boomy sub is usually a slow sub. An inexpensive ported sub with an extremely small magnet reacts slower to multiple signals than one with a larger magnet and more available current.

The part in bold is why this myth persists. There is ONE signal.

A musical waveform is a (potentially) infinite number of sine waves superimposed into one. Use an audio editor like Sound Forge and generate a 30 Hz sine wave at whatever amplitude you desire. Then generate a 1 khz sine wave at any amplitude you desire. Paste Mix them together. What do you get? One sine wave that contains both of the frequencies. The amplitude of the composite signal will be dependent on the relative amplitudes of the signals that were combined.

Note also that the subwoofer won't 'know' that the signal was artificially generated by SF or a sampler, whether it is 'music', or whether it is part of a soundtrack of a movie.

A boomy sub is one that cannot reproduce that signal accurately.

 

[mtrycrafts]

.....Mtrycrafts, I can't help but lean in your direction on this topic.....

Hey, what are freinds for if not to lean with them

 

[mtrycrafts]

Absolutely correct, Sheep. 'Fast' has no meaning when you are talking about a subwoofer or any speaker for that matter. I believe the reason some people make a distinction between 'good for music' vs 'good for movies' is that movie soundtracks often have far lower bass than music and the sub that is deemed better for music simply can't produce the lower frequencies with low distortion and high SPL.

I call fast speakers tweeters
Interesting how urban legends just never die no matter what. But then, it also applies to other consumer markets. Audio doesn't have an exclusive right to them

 

[mtrycrafts]

I have to add a caveat here. Speakers are by far the largest source of distortion in the audio chain. Even a "low distortion" subwoofer driver will still have distortion products in the single digits and sometimes into the double digits near the edges of its frequency response.

Yes, that is a very good caveat indeed.
Don't forget, subs are measured to 10% distortion limits That comes with volume as well. But then speakers as a whole will have more distortion as you increase the volume.

 

[Sheep]

The part in bold is why this myth persists. There is ONE signal.

A musical waveform is a (potentially) infinite number of sine waves superimposed into one. Use an audio editor like Sound Forge and generate a 30 Hz sine wave at whatever amplitude you desire. Then generate a 1 khz sine wave at any amplitude you desire. Paste Mix them together. What do you get? One sine wave that contains both of the frequencies. The amplitude of the composite signal will be dependent on the relative amplitudes of the signals that were combined.

Note also that the subwoofer won't 'know' that the signal was artificially generated by SF or a sampler, whether it is 'music', or whether it is part of a soundtrack of a movie.

A boomy sub is one that cannot reproduce that signal accurately.

Well done, Very nice.

Buck, stop supporting the myth

Mytry,

Read my first post. I was talking about 20-80hz with 0%THD. Hypothetically speaking.

 

[mtrycrafts]

I may be the only one (or one of three) on this board that disagrees, but not necessarily. Sheep, you say "good", which I fully agree with. Had you said "great," then I'd have to totally disagree.

MacManNM and I toyed with all the SVS subs for hours with music, as well as movies. You cannot beat SVS subs for the deepest HT and house bass, but they purposely tune their boxes this way. Since their boxes are HUGE relative to driver size, they lack in the upper range compared to the best sealed boxes IMHO. Now if you're talking budget, the SVS is most likely the better buy. You'd have to spend 1.5X or more for a sealed 15" enclosure that gives you that depth charge bass.

Mule wouldn't be looking for that "midbass" effect in a smaller sub if that were the case. He has two top of the line SVS subs.

Now don't get me wrong, these subs are excellent for music. Most home theaters have towers that will take over where these low flying SVS type subs leave off. It's when you pair up a small bookshelf to a PB12 ISD Plus II that you'll find other subs better with music.

The most discerning two channel music listeners will tell all of us to forget the subs altogether, and rely on their massive towers for full range sound.

It's mostly personal preference. I really enjoy listening to music with my sub on, and in 7 channel stereo. Once in awhile, I'll kick it into two channel pure direct with smooth jazz, but I still prefer the enveloping sound of all 7.1 drivers working in unison.

My 2.0 "music only" setup has two towers with 15" woofers, 6" midranges, and ribbon tweeters. No need for a sub, but it's a dinosaur.

You need to check out the sub measurements Tom Nousaine publishes periodically in S&V. Good subs will have uniform high level output to 80Hz, easy. Hence, your assumptions about subs may not hold much water?

 

[mulester7]

Originally Posted by Buckeyefan 1
A boomy sub is usually a slow sub. An inexpensive ported sub with an extremely small magnet "reacts slower to multiple signals" than one with a larger magnet and more available current.

The part in bold is why this myth persists. There is ONE signal.

....but the current, even though inductance, is still alternating, MDS....at sixty cycles....shouldn't we think excursion in both directions, with a weak magnet trying to constrain and draw, from what Buck said?....

.....ports of a sub?......

.....ports too constraining?....whistle?....boom?.....

.....ports too loose?....splat-mud?....element-bottom-out-whacko-backplate?....

 

[bpape]

When I was referring to sub speed - I agree that the amp is in control of stopping it. However, STARTING it is another story. Sure - it's still the amp's job. Getting a big beastie driver to start quickly enough to keep up with the smack of the drum head on an electrostatic panel that will be pretty much done moving by the time the woofer cone gets moving is a real challenge.

The problem is that the very things that make a driver good for a deep bass sub (stiffness/size/etc.) in order to be able to play low/loud/clean are the things that make it more difficult to get it started moving.

I'll agree I took an extreme case. I did it on purpose. (and 63's are still available as are some of the original 57's, the Futterman's, and the Bernings).

Don't get me wrong. I think there is a lot of overlap in the desirable characteristics between the 2. And, I think you can have a system that does both well. I think my system does both well (Dynaudio Contours, ServoDrive ContraBass).

What I'm saying is that if you look for a good music system AND you pay attention to the 'extra' things that HT usage requires, you'll likely succeed and be very pleased. If you go out and pick something purely based on HT performance parameters, you're much more likely to be disappointed in terms of music performance.

Seriously, how many of the speakers designed purely for HT really image worth diddly? How many of them can do timbre correct violins, piano, etc.? How many of them when set up in a proper 2 channel room could throw an image more than speaker width wide and 6" deep? Very few. Why? Because they don't have to. In HT, you have 6-8 channels to develop the surround field. In stereo listening, you depend on the main 2 and the room for the image.

Now, take something that is designed primarily as a music speaker (Paradigm Studios, Dynaudio, Totem, Thiel, etc.) and couple them with the appropriate amplification and they do a great job at HT.

 

[Buckeyefan 1]

Well done, Very nice.

Buck, stop supporting the myth

This is simple mechanics guys. Why do you think a bass drum sounds different than a rack tom?

Sheep,

Go to James Birch and Lucio Proni's site, and see why they've chosen sealed subs for home theater. In their Mobile Audio section, see why they say "for SQ go sealed, for SPL go ported.

Should these words be used to describe poor subs? sluggish, sloppy, or muddy?

The part in bold is why this myth persists. There is ONE signal.

Change the word "signal" to "program material."

 

[Buckeyefan 1]

You need to check out the sub measurements Tom Nousaine publishes periodically in S&V. Good subs will have uniform high level output to 80Hz, easy. Hence, your assumptions about subs may not hold much water?

You say "good subs." What about "junk subs?" You and I know subwoofers produce bass above 80Hz. This is key when one is shopping for a "good sub" with small satellite surrounds. Please tell us when a good sub becomes a bad sub.

 

[edwelly]

First off, you guys all know more than I do so take what I say with a grain of salt..

I spent 5 years in car audio; I had around 10K in my car at one point (this was over 10 years ago so back then 10k was a lot). I even competed some. However, there were some guys who had vest over 100k in their systems, Richard Clark was one of them. Their systems were designed to be musical but the were very dry and flat. Not really that great of a sound. THOSE GUYS ALWAYS WON but most people didn't like the sound.
Now take a concert or just a band in a bar – that’s music and it doesn’t sound that great we being compared to a Telarc CD.
When I think of a musical system, I think of a very flat (in terms of frequency, no valleys or hills) and very dry sounding. That is recorded music.
When I think of HT, I think of things happening now; voices, car crashes, doors shutting.
I compare HT and music to a concert and a cd. Those are totally different.
I used to follow Dave Matthews Band around and I loved there concerts, but there I nothing like listening to it on a CD at home.

As far as the sub fast/slow debate – I am staying out of that one...

 

[MDS]

Change the word "signal" to "program material."

Ok, there is one "program material'. The program material is a waveform.

 

[MacManNM]

Well I'm going to jump in here guys.

Ok, music sub vs. HT sub:

A Music sub doesn’t really need to go down any lower than 30Hz, a HT sub IMO needs to go down to sub 20Hz. It is very difficult to design a sub that plays from the teens of Hz to say 100Hz linear, with low distortion and great accuracy. I believe that this accuracy is sacrificed when getting this lower extension. Hence I believe that something like an SVS or HSU sub is better for HT, whereas something like a Dayton Titanic is better for music.

As far as fast or slow subs, there is no such thing. The crisp "tight" sound you hear with a sub is being produced by the midrange and tweeters, it is a fast rise time signal.

A sub is boomy because
1. Poor driver quality
2. Poor amp quality
3. Poor enclosure design/construction.

Any one or combination of the above will cause it to be boomy, or the correct term: not accurate.

I do believe that there are systems that can sound good for HT and bad for music. Dif Tech speakers would be a good example of this. They are absolutely terrible speakers for music. However, when you put them together in a multi channel setup and watch a movie, they don't sound too bad.

The opposite is my McIntosh XR16's, great for 2ch music but I don't care for them in my HT setup. They don't seem to have the dynamics that other speakers have, but when I listen to 2ch music, I haven’t heard anything close to them (there is a price consideration there).

So this is just my opinion and there is a lot to be said on the subject.

 

[Sheep]

This is simple mechanics guys. Why do you think a bass drum sounds different than a rack tom?

Sheep,

Go to James Birch and Lucio Proni's site, and see why they've chosen sealed subs for home theater. In their Mobile Audio section, see why they say "for SQ go sealed, for SPL go ported.

Should these words be used to describe poor subs? sluggish, sloppy, or muddy?




Change the word "signal" to "program material."

Buck,

You make it sound like all ported subwoofers are hopeless, and every sealed sub is tight. I have heard many nasty sounding sealed subs, One was my brothers. I have also heard great sounding ported subs. Either one can be good or bad, it depends on the box, driver and amp. I think saying sealed is tight, ported is boomy, it just plain "lazy".

http://www.hometheaterhifi.com/volume_11_3/svs-pb2-ultra-subwoofer-9-2004.html

Look at the distortion figures from this subwoofer.
At 16hz, it was 15%
At 20hz, it was 6%

That is really clean for those frequency's, and this is where my point lies. Music doesn't go below 20hz according to everyone. This subwoofer has 6%THD at 20, and it gets better and better. It also hits 16Hz at 100dB with 15% THD. Not the best, But this subwoofer can do both.

Sheep

 

[MacManNM]

Buck,

You make it sound like all ported subwoofers are hopeless, and every sealed sub is tight. I have heard many nasty sounding sealed subs, One was my brothers. I have also heard great sounding ported subs. Either one can be good or bad, it depends on the box, driver and amp. I think saying sealed is tight, ported is boomy, it just plain "lazy".

http://www.hometheaterhifi.com/volume_11_3/svs-pb2-ultra-subwoofer-9-2004.html

Look at the distortion figures from this subwoofer.
At 16hz, it was 15%
At 20hz, it was 6%

That is really clean for those frequency's., and this is where my point lays. Music doesn't go below 20hz according to everyone. This subwoofer has 6%THD at 20, and it gets better and better. It also hits 16Hz at 100dB with 15% THD. Not the best, But this subwoofer can do both.

Sheep

Sheep you have to understand that when Buck and I were younger, most of the really good speakers were sealed enclosures. When we went around listening to speakers we both could pick out the bass reflex units in a millisecond.

In general, a vented enclosure is designed to artificially enhance the low frequency extension of a speaker. The most accurate design for speakers is an infinite baffle design. The sealed enclosure is closer than a vented enclosure to that design. Buck isn't saying that vented speakers are junk. If you were to take comments of equal quality, build them into speakers, one set vented, one set sealed, and the other in an infinite baffle. The IB would be the most accurate; the sealed would be 2nd, and the vented 3rd. The fact is that sealed enclosures have a very predictable bass roll off, compensating for this is very easy.


Also, music really doesn't go below 30Hz (unless you are listening to some pipe organ or really wild electronic stuff), so why have a speaker that can play below that for music? All it is doing is wasting power reproducing things that aren't supposed to be there IE distortion from the components, and its own distortions.

 

[miklorsmith]

Speed = ability for the driver to accelerate and decelerate to the TRUE scale of the signal. This is inversely proportional to my ability to describe it with physical formulae.

Anybody not believing that speed is a real phenomenon in loudspeaker design, please get out of the lab and in front of some electrostats, Lowthers, Fostexes, or any other of a number of speakers that are faster than whatever schlock you're listening to.

 

[jaxvon]

I know what you're talking about Miklorsmith. It's the transient response of the driver. Here's one PDF file comparing the TRS of a driver to a lower quality one:

http://www.murata.com/catalog/p57e.pdf

On a side note, I've always thought that such a driver design with a "breathing" excursion would yield excellent sound and off axis response. Apparently I'm not the only one.

Edit: A white paper from Adire: http://www.adireaudio.com/Files/TechPapers/WooferSpeed.pdf

 

[Buckle-meister]

The most discerning two channel music listeners will tell all of us to forget the subs altogether, and rely on their massive towers for full range sound.

He he he!

Regards