Question about number and kind of drivers

[skers_54]

Why would the bass of a "Transmission Line" box sound different from a "ported" box in a room?

From my understanding, TLs have a 2nd order roll off rather than 4th and generally have a lower Q. Anything more detailed will have to come from TLS Guy (if you ask nicely)

 

[AJinFLA]

From my understanding, TLs have a 2nd order roll off rather than 4th and generally have a lower Q.

"Q" as you use the term would describe the (free space) LF roll off..and might begin in a "TL" as 2nd order, but eventually become 4th order. A similar LF roll off can be done with a "port", such as EBS. What would make these sound perceptually different in a (1/2, 1/4 space?) room?

Anything more detailed will have to come from TLS Guy (if you ask nicely)

So far he has replied with pure anecdote. Missing were the facts and/or data to support any claim.

cheers,

AJ

 

[skers_54]

"Q" as you use the term would describe the (free space) LF roll off..and might begin in a "TL" as 2nd order, but eventually become 4th order. A similar LF roll off can be done with a "port", such as EBS. What would make these sound perceptually different in a (1/2, 1/4 space?) room?


So far he has replied with pure anecdote. Missing were the facts and/or data to support any claim.

cheers,

AJ

What can be done and what is commonly done are two completely different things. I made a broad generalization about two classes of speakers and it shouldn't be taken as anything more than that. Most decent ported speakers have a Qtc ~ .707, while TLs I believe are typically closer to .5. Yes, the roll-off will eventually be the same but that's not until the speaker is 10+ dB down (where output is practically negligable).

I'm not an expert, but from what I understand TLs reinforce low frequency output without acting as a tuned system by selectively dissipating the higher-frequency back-wave energy. This is fundamentally different from a ported speaker, so it is very plausible that a TL will sound distinctive. This wikipedia article is decent has has some good links.

http://en.wikipedia.org/wiki/Acoustic_transmission_line

 

[Swerd]

… So far he has replied with pure anecdote. Missing were the facts and/or data to support any claim.

Peer-reviewed scientific journals require facts and supporting data to back up claims. I'm reasonably certain that this is web site is not such a journal. It is a forum for discussion, sharing information and experience, and exchanging opinions.

While I may agree (in principle) with your wish that others document all claims with evidence, I think your quarrelsome method is inappropriate. It suggests that you may be more interested in scoring argument points than in actually answering a question.

 

[AJinFLA]

What can be done and what is commonly done are two completely different things. I made a broad generalization about two classes of speakers and it shouldn't be taken as anything more than that.

It wasn't. I simply asked why, to see if you had any factual, non-anecdotal evidence to support the statement.

Most decent ported speakers have a Qtc ~ .707, while TLs I believe are typically closer to .5. Yes, the roll-off will eventually be the same but that's not until the speaker is 10+ dB down (where output is practically negligable).

You confused. Again, Q describes the total LF roll off. Now you are adding caveats like "most" and "typical". You are also confusing free space simulation programs with real word 1/4 space rooms with LF loading. Show me the measured LF roll off of a TL freespace and in room and then tell me why it will be perceptually different from similarly shaped LF roll off ported design...and when this was determined.

I'm not an expert, but from what I understand TLs reinforce low frequency output without acting as a tuned system by selectively dissipating the higher-frequency back-wave energy.

That is nonsense. LF output cannot be increased by "selectively dissipating the higher-frequency back-wave energy". The LF "reinforcement" is due to resonance, just like a ported loudspeaker.

This is fundamentally different from a ported speaker, so it is very plausible that a TL will sound distinctive.

No it isn't. The only difference might be the shape of the free space roll off (to the "typical" ported speaker), but again, "ports" can be used to produce a similar shape. Rather than "plausible", is there any factual data to support any of these type claims?

This wikipedia article is decent has has some good links.
http://en.wikipedia.org/wiki/Acoustic_transmission_line

Thanks, but I took Physics. Don't need wiki articles for such basics. Especially wiki articles that have no correlation to perceptual, in room LF sound quality. The actual claim.

 

[AJinFLA]

While I may agree (in principle) with your wish that others document all claims with evidence

I wished no such thing. I asked something specific. Back up your claim about why TL's "sound different" from ports, with facts rather than anecdote.

I think your quarrelsome method is inappropriate. It suggests that you may be more interested in scoring argument points than in actually answering a question.

Is this your best non-diversionary answer to my questions about your claim?

 

[Swerd]

I wished no such thing. I asked something specific. Back up your claim about why TL's "sound different" from ports, with facts rather than anecdote.

Ok, you didn't wish it, you demanded it.

Is this your best non-diversionary answer to my questions about your claim?

I stated opinions and made no claims.

I could also claim that you're being irritatingly argumentative, but my only supporting evidence would be your own words. So, I'll call it opinion and leave the claims to others.

 

[AJinFLA]

So basically you parroted a claim about TL's vs ports without understanding the fundamentals or possessing any evidence of such...and is now upset and irritated at me for daring ask for an explanation. Cool .

 

[Seth=L]

This thread went from helpful to hateful in less than a few hours.

 

[skers_54]

It wasn't. I simply asked why, to see if you had any factual, non-anecdotal evidence to support the statement.


You confused. Again, Q describes the total LF roll off. Now you are adding caveats like "most" and "typical". You are also confusing free space simulation programs with real word 1/4 space rooms with LF loading. Show me the measured LF roll off of a TL freespace and in room and then tell me why it will be perceptually different from similarly shaped LF roll off ported design...and when this was determined.


That is nonsense. LF output cannot be increased by "selectively dissipating the higher-frequency back-wave energy". The LF "reinforcement" is due to resonance, just like a ported loudspeaker.


No it isn't. The only difference might be the shape of the free space roll off (to the "typical" ported speaker), but again, "ports" can be used to produce a similar shape. Rather than "plausible", is there any factual data to support any of these type claims?


Thanks, but I took Physics. Don't need wiki articles for such basics. Especially wiki articles that have no correlation to perceptual, in room LF sound quality. The actual claim.

I'm going to go out on a limb and agree with Swerd. I said I wasn't an expert and you're looking for expert-level answers. Since you're too lazy to do your own leg work, Martin King explains it all in this 46 page document that the wiki linked (and why I included it). I have no idea how this theory translates to 1/4 space. I don't have an acoustical engineering degree (just lowly biomedical).

http://www.quarter-wave.com/TLs/TL_Anatomy.pdf

Here's an excerpt from page 16: "Adding fiber stuffing to a
transmission line significantly attenuates the higher order standing waves but does not fundamentally change the basic physics"

I didn't say the system is non-resonant, which is what you're implying. Every oscillatory system has resonance, including your nervous system. That's where the physiological tremor comes from. If you have a problem with it call Martin King.

This was a perfectly useful thread until you characteristically started the personal attacks. I never claimed to be an expert on TL theory (quite the opposite in fact), so I don't know why you're having such a hissy fit. I've got a neuroscience test to study for so you're going to have to find your own primary literature on this subject. OP, sorry for the derailment.

 

[tesseract]

jjwagner18, if you are shopping at the NFM in Omaha instead of the one in KC, check around the corner at Custom Electronics. IMO, they will have better gear than the Mart. I bought some B&W DM601's there, used, 12 years ago for a really good price. They also have used electronics. Their new stuff is pretty good, too. Another place to check out is The Sound Environment. You should be able to come up with a decent system at the $1500 mark at either place, and their staff has way more knowledge than a big box store employee.

Give smaller speakers a chance. The box is smaller and prone to less resonance, and the small size lends itself well to better imaging than many large floorstanders. You will be surprised at the bass that can be had. Smaller speakers also leave more money in the coffers for a better source, you could buy a universal player and discover hi rez music (Super Audio CD, DVD-Audio), along with CD playback.

(Edit, just read further into the thread and seen you were in KC. Do give a listen to your local dealers, see what they have to offer. ID companies also have big bang for the buck, but at least go listen to what is available locally.)

 

[tesseract]

I'm not an expert, but from what I understand TLs reinforce low frequency output without acting as a tuned system by selectively dissipating the higher-frequency back-wave energy. This is fundamentally different from a ported speaker, so it is very plausible that a TL will sound distinctive. This wikipedia article is decent has has some good links.

This is correct.

So basically you parroted a claim about TL's vs ports without understanding the fundamentals or possessing any evidence of such...and is now upset and irritated at me for daring ask for an explanation. Cool .

Swerd and others have been pretty cool about it, actually. Maybe "upset and irritated" is what you are shooting for, but you have missed the target.

The info you asked for was offered, and more is readily available for research, at your leisure of course.

 

[TLS Guy]

"Q" as you use the term would describe the (free space) LF roll off..and might begin in a "TL" as 2nd order, but eventually become 4th order. A similar LF roll off can be done with a "port", such as EBS. What would make these sound perceptually different in a (1/2, 1/4 space?) room?


So far he has replied with pure anecdote. Missing were the facts and/or data to support any claim.

cheers,

AJ

That is because we have been over this so many times before.

The TL goes back pre WW II with Paul Voight's quarter wave pipe.

Then post war Ralph West designed a folded quarter wave pipe which was called the Decca corner horn. This confused the issue, because it was not a horn. A quarter wave pipe rolls off fourth order.

The Ralph West's colleague Dr Bailey was seconded to Radford, where he joined Irvin Freed and John Wright. They developed a reverse tapered pipe damped to the point where one peak of impedance was suppressed. This resulted in a low Q (Q=0.5) with bass extension. The result was the Radford and later the Fried monitor loudspeaker. John Wright went on to found TDL which produced exclusively TL speakers.

Also watching this with interest were Jim Rogers, Raymond Cooke of KEF and Peter Walker of Quad.

These individuals collaborated on the legendary BBC triamped TL monitor loudspeakers. That has been the place of the start of my endeavors.

The problem was that there was no mathematical model of operation, until George Augspurger delivered his three classic papers to AES in 2000.

Martin King also independently came up with models and spread sheets and introduced the concept of the mass Loaded TL which is a tapered line with tuning. There are endless arguments about whether this is a TL. Certainly it is not a classic design, and rolls off fourth order.

There is a lot of misunderstanding about the effect of the damping of an aperiodic TL, with people who have never built one claiming it is an IB with no port output. I can assure you that this is not so. The port output is reduced compared to an undamped TL, however there is significant bass extension from the port over 1.5 octaves. That has been measured by many including myself.

Here is further information for you.

http://www.t-linespeakers.org/readme1st.html

http://www.quarter-wave.com/TLs/Introduction.pdf

http://www.quarter-wave.com/TLs/TL_Anatomy.pdf

The only commercial firm that I'm aware of that produces the classic reverse tapered aperiodically damped TL is a British speaker firm PMC

Here are my construction pictures.

The finished product.

You can read some details, in my review of Audyssey.

The result is deep non resonant bass, that touches lightly, and never advertises itself. You just forget it is reproduced.

 

[AJinFLA]

That is because we have been over this so many times before.

We have? Was there as much hand waving, useless links that I'm already well aware of and history lessons previously (and yet another posted pic of your system )?
Bottom line (no pun intended), is that other than "Because I said so", there is nothing to support the claim of difference of TL vs port "sound" in a room. No measurements, no data. None. Zero.
The bass quality will simply depend on the in room FR averaged at the listener position(s) and temporally, the rate of decay of resonances - which for the TL and Port, will be like any other monopole.
If you want a link that isn't frivolously useless with regards to the actual question of bass sound quality, try this. You will have to log in to see the data, but there's lots of it, rather than lot's of hand waving .

 

[TLS Guy]

We have? Was there as much hand waving, useless links that I'm already well aware of and history lessons previously (and yet another posted pic of your system )?
Bottom line (no pun intended), is that other than "Because I said so", there is nothing to support the claim of difference of TL vs port "sound" in a room. No measurements, no data. None. Zero.
The bass quality will simply depend on the in room FR averaged at the listener position(s) and temporally, the rate of decay of resonances - which for the TL and Port, will be like any other monopole.
If you want a link that isn't frivolously useless with regards to the actual question of bass sound quality, try this. You will have to log in to see the data, but there's lots of it, rather than lot's of hand waving .

I can assure you that systems with a Q of 0.5 have a very different quality from a Q of around 1.0

A lot of listeners prefer a Q of around 0.7, however classical listeners tend to go for Q of around 0.5 and that is what I prefer. It has nothing to with being monopole or bipole.

Now a QB4 box can not achieve a q of 0.5. You can with a sealed box, but F3 is high so you need and expensive driver and a lot of Eq. A TL allows for low Q at very attractive efficiency especially in the last octave.

I agree it takes a lot of real estate, but that is a price I'm prepared to pay.

 

[jjwagner18]

When I said I would go with a $1500 set of speakers on blind faith I was mostly being facetious. I still plan on emailing Jim before I make my decision..I may possibly still go with bookshelves. I've done quite a bit of research and have learned a lot from this thread. I'm not an audiophile but I could see myself becoming pretty picky with time and If I'm going to invest hundreds of dollars in speakers and receiver I might as well go all out. It wouldn't be that much harder to get them. I would only have to save for another 3-5 months on top of what I normally would have saved to "go all out." That, to me, seems very logical.

It's good to know the SongTowers aren't too difficult to power. I've heard Harmon and Denon are some of the best choices.

What kind of money do you think I should put into a receiver for these speakers? At least $200? At least $400? More?

 

[skers_54]

When I said I would go with a $1500 set of speakers on blind faith I was mostly being facetious. I still plan on emailing Jim before I make my decision..I may possibly still go with bookshelves. I've done quite a bit of research and have learned a lot from this thread. I'm not an audiophile but I could see myself becoming pretty picky with time and If I'm going to invest hundreds of dollars in speakers and receiver I might as well go all out. It wouldn't be that much harder to get them. I would only have to save for another 3-5 months on top of what I normally would have saved to "go all out." That, to me, seems very logical.

It's good to know the SongTowers aren't too difficult to power. I've heard Harmon and Denon are some of the best choices.

What kind of money do you think I should put into a receiver for these speakers? At least $200? At least $400? More?

I'd get the cheapest Denon, Onkyo or Marantz that has pre-outs and the features you want. HDMI and Audyssey MultiEQ are probably the 2 biggies, with video transcoding following. Upconversion in most receivers isn't any better than what's in your player or TV so I wouldn't worry about that. Pre-outs will help if/when you move into a bigger place. The SongTowers do dip down to 4 ohms, so an external amp would probably help then.

 

[tesseract]

It's good to know the SongTowers aren't too difficult to power. I've heard Harmon and Denon are some of the best choices.

What kind of money do you think I should put into a receiver for these speakers? At least $200? At least $400? More?

Does it have to be a receiver? Integrated amps work very well in a minimalist 2 channel system. If a receiver is mandatory, then check ebay for inexpensive h/k factory refurbs and closeouts.

Also, if you do decided to go with bookshelf speakers, I wouldn't place them on a bookshelf or near (18" or less) any boundaries that will reflect the speakers direct output. Consider stands as part of a smaller speaker system, this will give you much better sound and flexibility in placement.

That said, if it were my $1500, I would go with the Salk ST and the best integrated amp I could afford.

 

[AJinFLA]

I can assure you that systems with a Q of 0.5 have a very different quality from a Q of around 1.0

Who said different?

A lot of listeners prefer a Q of around 0.7, however classical listeners tend to go for Q of around 0.5 and that is what I prefer.

What relevance does any of this have to your claim of "TL" sounding different than "port"?
You prefer Q 0.5? Don't tell me, show me (measurements) you have achieved this with your system. If it's a TL, you haven't...and cannot show this.

It has nothing to with being monopole or bipole.

Huh? What the heck are you talking about? Monopole and bipole at LF are the same thing (omnipole). Who said anything about a bipole?? What does this have to do with TL vs port?

Now a QB4 box can not achieve a q of 0.5.

Nor can a TL, yours included.

You can with a sealed box, but F3 is high so you need and expensive driver and a lot of Eq.

Nonsense. A sealed Q of 0.5 can be easily achieved without expense or eq. So what if the free space F3 is high?

A TL allows for low Q at very attractive efficiency especially in the last octave.

No different than ported (EBS). Including "sound"...the claim.

I agree it takes a lot of real estate, but that is a price I'm prepared to pay.

This makes no sense whatsoever. A stereo pair of fullrange TL's has to be positioned in room like any other monopole...with the resulting sub-par bass quality and performance.

 

[jjwagner18]

Does it have to be a receiver? Integrated amps work very well in a minimalist 2 channel system. If a receiver is mandatory, then check ebay for inexpensive h/k factory refurbs and closeouts.

Also, if you do decided to go with bookshelf speakers, I wouldn't place them on a bookshelf or near (18" or less) any boundaries that will reflect the speakers direct output. Consider stands as part of a smaller speaker system, this will give you much better sound and flexibility in placement.

That said, if it were my $1500, I would go with the Salk ST and the best integrated amp I could afford.

What is the difference betweena reciever and an integrated amp? I've never heard of that?