DIY JBL Speaker Cabinets and Components Question

[MrBoat]

While you can squeeze deeper bass out of these type of drivers, but you should avoid doing so. High-pass filter all that stuff out. These drivers do not have the excursion to pull that type of bass off well. They run into heavy distortion, and it can also mess up the rest of the spectrum you want it to play in as well. This goes for the Tempest as well as the JBLs. Deep bass is not their wheelhouse.

By deeper, I mean capable below 80, or even 60 hz, or not having as much of the bass guitar having to live in the subwoofer with all of the other sub bass freq. I'm sure a lot of it has to do with the size of the woofer, cabinet and how it is tuned as well, along with room size/gain, how many channels, type of music etc. I've tried the Tempests a lot of different ways. They really do well into the 40s with music.

Another thing that is often overlooked is, how much of these settings or approaches revolve around correcting acoustically bad spaces and what's being sacrificed to do so from the get-go.

I'm holding out for an auto EQ that tells people that "Hey, your speakers are the wrong size and I can't help you."

 

[MrBoat]

It's not that they're "musical", they just don't go very low and that it's frequency range fits some people's definition of a musical range. Just a matter of choosing a driver appropriate to the goal....

I agree and I understand that.

I also think this is valid in many more situations than may be realized. I can see times where I would gladly sacrifice freq below 30hz for a really potent mid bass or more clarity in the ranges above 40hz.

I just find the general consensus with regard to sub bass, a bit too broad. I'm trying though. I'm willing to give it a shot as prescribed. But when I start seeing, 4, 6, 8-18 or 21" subwoofers in a room, something just seems off to me. At least with music.

 

[lovinthehd]

I agree and I understand that.

I also think this is valid in many more situations than may be realized. I can see times where I would gladly sacrifice freq below 30hz for a really potent mid bass or more clarity in the ranges above 40hz.

I just find the general consensus with regard to sub bass, a bit too broad. I'm trying though. I'm willing to give it a shot as prescribed. But when I start seeing, 4, 6, 8-18 or 21" subwoofers in a room, something just seems off to me. At least with music.

Not all systems have only music as a goal. There are "subs" that are concentrating on mid bass, search for mid-bass modules.

 

[MrBoat]

Not all systems have only music as a goal. There are "subs" that are concentrating on mid bass, search for mid-bass modules.

Again, I agree. But I also see a lot of people saying; "Music only." Yet we hardly ever see anyone recommend mid bass modules as part of the subwoofer scheme. I often see a comparatively small set of monitors with say a 4-6" woofer and the next step up being a 15" or beyond subwoofer. Seems a good mid bass module would be the obvious transition between the two.

 

[MrBoat]

Not all systems have only music as a goal. There are "subs" that are concentrating on mid bass, search for mid-bass modules.

When I was reading about the PA460 driver, I was under the impression that was actually what they were essentially building whether they were calling it that or not.

Just curious is all. It intrigues me. I would like to try one just for S&G. After listening to the Eminence woofer in the Tempests, I can kind of get a feeling that it would not be a bad thing, especially if that's all that was asked of it to do. I have been reading a lot about it, regardless.

 

[Verdinut]

I agree and I understand that.

I also think this is valid in many more situations than may be realized. I can see times where I would gladly sacrifice freq below 30hz for a really potent mid bass or more clarity in the ranges above 40hz.

I just find the general consensus with regard to sub bass, a bit too broad. I'm trying though. I'm willing to give it a shot as prescribed. But when I start seeing, 4, 6, 8-18 or 21" subwoofers in a room, something just seems off to me. At least with music.

There is nothing wrong with the use of big subwoofers or woofers. If you want to reproduce very low frequencies at a certain volume with low distortion, you need to displace a lot of air and the size of the cone area is of most importance. When the frequency goes down one octave, the moving cone has to move 4 times as much.

A good subwoofer like those of the Dayton RSS-HF series will give you a good musical reproduction with low distortion and I know that for a fact because I use them in my 3 front speakers with excellent results.

Not all audiophiles need subwoofers. It all depends on the type of music you listen to and whether or not you like to watch action films. But in my case, as I like pipe organ music, I want the speakers to be able to reproduce notes put out by a 32 foot stop pipe, with fundamental frequencies from 16 Hz to 32 Hz.

 

[MrBoat]

There is nothing wrong with big subwoofers or woofers. If you want to reproduce very low frequencies at a certain volume with low distortion, you need to displace a lot of air and the size of the cone area is of most importance. When the frequency goes down one octave, the moving cone has to move 4 times as much.

A good subwoofer like the Dayton RSS-HF series will give you a good musical reproduction with low distortion and I know for that a fact because I use them in my 3 front speakers with excellent results.

Not all audiophiles need subwoofers. It all depends on the type of music you listen to and whether or not you like to watch action films. But in my case, as I like pipe organ music, I want the speakers to be able to reproduce notes put out by a 32 foot stop pipe, with fundamental frequencies from 16 Hz to 32 Hz.

I don't mind big woofers either. I actually prefer them. There's also an ambient 'presence' that resides in larger cones and the cabinets that house them that is often overlooked these days in exchange for efficiency and aesthetics, of all things.

 

[Verdinut]

Again, I agree. But I also see a lot of people saying; "Music only." Yet we hardly ever see anyone recommend mid bass modules as part of the subwoofer scheme. I often see a comparatively small set of monitors with say a 4-6" woofer and the next step up being a 15" or beyond subwoofer. Seems a good mid bass module would be the obvious transition between the two.

In three-way speakers which I built, I have been using two 5 inch mid-woofers with either one 12" or a 15" subwoofer with excellent results. The success results from the choice of drivers which have frequency responses that obviously make a good match.

 

[Verdinut]

Your present system sounds like it could be quite good. The Dayton bass driver you mentioned is one I have long thought about fooling around with for some DIY projects. Very nice Le on that woofer, it should be very linear and have very low distortion. Do you have any pics of your system? What is the frequency response like?

The picture has been uploaded after reducing its size with Photoshop.

The center cabinet seems to be narrower but it is the same size.

 

[MrBoat]

In three-way speakers which I built, I have been using two 5 inch mid-woofers with either one 12" or a 15" subwoofer with excellent results. The success results from the choice of drivers which have frequency responses that obviously make a good match.

This is part of what I reckon I am getting at. The matching of drivers. And the thought that perhaps some of these larger, mid range/bass pro drivers may do just that in some cases. Even considering the mechanics of them, the type of surrounds they use, response with regard to excursion etc.

 

[TLS Guy]

While you can squeeze deeper bass out of these type of drivers, but you should avoid doing so. High-pass filter all that stuff out. These drivers do not have the excursion to pull that type of bass off well. They run into heavy distortion, and it can also mess up the rest of the spectrum you want it to play in as well. This goes for the Tempest as well as the JBLs. Deep bass is not their wheelhouse.

Shady, the drivers do not necessarily need high excursion. A sealed enclosure only has the driver to excite air vibration. A driver cone is just dreadfully inefficient at doing that. I really dislike using sealed enclosures for deep bass. Apart from reduced cabinet size it is all downsides. There is no free lunch. However you design a speaker there is a direct relationship to lower efficiency, cone excursion and large power requirements with reduced cabinet size.

In a well designed bass system, you can get prodigious bass with small cone excursion and no need for mega amps. I don't use sub drivers in my TLs, yet they shake the floor so hard they threaten structural damage in movies. The measured distortion is no higher than 2% at high spl.

A well designed TL, horn and carefully designed reflex enclosures do not need high power and massive cone excursion.

I have come to the conclusion that a lot of subwoofer design is wrong headed. You do not need gobs of power for the low bass. I use minute amounts of power reproducing the last octave in all my systems. They sound very well balanced indeed, and measure very well. Only my Eagan system uses a high pass filter on the bass section. The sum of driver roll off and high pass filter is fourth order at 90 Hz, the sub bass system is driven above its acoustic roll off, so acoustically the bass roll (low pass) is entirely acoustic, since it is a coupled cavity system. The splice is perfect by measurement. It is an integrated system design by intent, which I believe all reference systems should be.

The other idea which is totally ridiculous and a very bad idea is mid bass units.

The best reproduction comes from using wide band drivers. The wider the better. The worst reproduction comes form closely spaced crossovers. The further apart crossovers are the better, otherwise you have a lot of driver interference and band pass gain problems.

And lets get one thing straight, 20 Hz to 500 Hz is bass period.

 

[shadyJ]

Shady, the drivers do not necessarily need high excursion. A sealed enclosure only has the driver to excite air vibration. A driver cone is just dreadfully inefficient at doing that. I really dislike using sealed enclosures for deep bass. Apart from reduced cabinet size it is all downsides. There is no free lunch. However you design a speaker there is a direct relationship to lower efficiency, cone excursion and large power requirements with reduced cabinet size.

In a well designed bass system, you can get prodigious bass with small cone excursion and no need for mega amps. I don't use sub drivers in my TLs, yet they shake the floor so hard they threaten structural damage in movies. The measured distortion is no higher than 2% at high spl.

A well designed TL, horn and carefully designed reflex enclosures do not need high power and massive cone excursion.

I have come to the conclusion that a lot of subwoofer design is wrong headed. You do not need gobs of power for the low bass. I use minute amounts of power reproducing the last octave in all my systems. They sound very well balanced indeed, and measure very well. Only my Eagan system uses a high pass filter on the bass section. The sum of driver roll off and high pass filter is fourth order at 90 Hz, the sub bass system is driven above its acoustic roll off, so acoustically the bass roll (low pass) is entirely acoustic, since it is a coupled cavity system. The splice is perfect by measurement. It is an integrated system design by intent, which I believe all reference systems should be.

The other idea which is totally ridiculous and a very bad idea is mid bass units.

The best reproduction comes from using wide band drivers. The wider the better. The worst reproduction comes form closely spaced crossovers. The further apart crossovers are the better, otherwise you have a lot of driver interference and band pass gain problems.

And lets get one thing straight, 20 Hz to 500 Hz is bass period.

I agree with most of what you are saying. Yes, you can get great bass without needing a super high excursion driver or tons of amplification, but the problem then, for most people, is like you said Hoffman's Iron Law: now you need a large enclosure. Transmission Line Enclosures, like what you have, are large and complex, and as such, they are out of reach for a lot of people. A sealed enclosure is relatively inefficient, however it is small, and amplification is cheap nowadays anyway. Most ordinary people would consider a typical sealed 15" subwoofer a 'large' speaker, and a ported 15" a massive speaker.

Transmission Line theory is interesting, but the designs are not accessible for most people. A sealed 15" and a couple well-placed bookshelf speakers is enough to make most people happy and can be a nice little system, despite its compromises. Sadly, even that modest setup is far better than what we find in most people's homes, so transmission line enclosures are, understandably, rarely even mentioned when simple little systems can not even get a popular foot hold.

As for mid bass units, I think there are pros and cons to such a setup, but they should mostly be avoided since it is difficult to pull off. A lot of times typical corner placement of a subwoofer can leave some pretty large dips in mid bass frequencies at the listening position in a conventional room. In these instances, a mid bass unit can shore up that null neatly and powerfully. The problem is it really takes some know-how to pull off. Subs to shore up mid bass nulls is similar to what Earl Geddes recommends for multiple subwoofer systems: the responses of the subs themselves do not matter, only the response they generate in-room matters. For the most part however, mid bass units are too complicated to integrate into a system and seldom worth it anyway.

 

[shadyJ]

One more thing, I don't think that many people consider frequencies as high as 500 Hz to be 'bass'. There does not seem to be much agreement on the dividing line between bass and low mid range. For example, this guy says bass stops at a Middle C (300 Hz) and this site says 250 Hz. What is your argument for saying bass extends up to 500 Hz?

 

[TLS Guy]

One more thing, I don't think that many people consider frequencies as high as 500 Hz to be 'bass'. There does not seem to be much agreement on the dividing line between bass and low mid range. For example, this guy says bass stops at a Middle C (300 Hz) and this site says 250 Hz. What is your argument for saying bass extends up to 500 Hz?

Well I will ask you to do this. Connect a driver to a fourth order low pass filter at 500 Hz and feed full range program ahead of the filter. All you will hear is woofle and nothing decipherable. You will perceive that as bass, which it is.

There are other reasons from the design perspective. It is around the frequency where most speakers transition from half to full space radiators. It is also around the power divide. So the range from below 500 to 400 Hz is a very convenient place to put the start of the bass decades. 400 to 500 Hz to 2,500 to 3000 Hz to think of as midrange, and above that as HF.

For me, and I think a lot of others, that is a very helpful and useful way to look at things from a design perspective. For me it is highly practical. I know my mentors all thought along those lines.

 

[Verdinut]

It is impossible for a single cone loudspeaker to reproduce the full audible frequency range, without having off-axis high frequency response problems and intermodulation distortion among its limitations.

Loudspeaker manufacturers have developed 2-way, 3-way and 4-way systems with drivers properly designed to work best in a specific portion of the audible spectrum.

There are 2-way systems that sound very well but IMO, a 3-way system is preferable since it can be designed without the need for a crossover in the critical mid-range frequencies from 300 Hz to 3000 Hz.

A 4-way system is definitely more complex to design with the additional risk of phase problems. This is why I prefer a well designed three-way speaker.

 

[shadyJ]

Well I will ask you to do this. Connect a driver to a fourth order low pass filter at 500 Hz and feed full range program ahead of the filter. All you will hear is woofle and nothing decipherable. You will perceive that as bass, which it is.

There are other reasons from the design perspective. It is around the frequency where most speakers transition from half to full space radiators. It is also around the power divide. So the range from below 500 to 400 Hz is a very convenient place to put the start of the bass decades. 400 to 500 Hz to 2,500 to 3000 Hz to think of as midrange, and above that as HF.

For me, and I think a lot of others, that is a very helpful and useful way to look at things from a design perspective. For me it is highly practical. I know my mentors all thought along those lines.

An interesting exercise. One thing I did to see your point is take a random spoken word sound file and run it through a fourth order low pass at 500 Hz.
Here is the original.
Here is the low-passed version.
It is hard to hear what he is saying without the S sounds.

 

[TLS Guy]

It is impossible for a single cone loudspeaker to reproduce the full audible frequency range, without having off-axis high frequency response problems and intermodulation distortion among its limitations.

Loudspeaker manufacturers have developed 2-way, 3-way and 4-way systems with drivers properly designed to work best in a specific portion of the audible spectrum.

There are 2-way systems that sound very well but IMO, a 3-way system is preferable since it can be designed without the need for a crossover in the critical mid-range frequencies from 300 Hz to 3000 Hz.

A 4-way system is definitely more complex to design with the additional risk of phase problems. This is why I prefer a well designed three-way speaker.

Sorry to disappoint you but this 4" driver is a very pleasant listen, especially in TL. It has a surprisingly good bass response down into the 40 Hz range and no sudden break up modes. It has good performance to 20 KHz..

It is the Jordan Watts modular driver, which appeared on the scene in 1959.

It was the brain child of Ted Jordan. A brilliant designer and mathematician. It is a spun aluminum cone that is a geometric tractrix. There is no sudden break up mode, and the radiating area progressively decreases with frequency. That results in good performance on and off axis.

The suspension is unique, using Beryllium cantilevers which also act as the lead in wires.

These units make a wonderful center in a small sealed enclosure crossed at 90 Hz.

I don't think there is anything hard and fast about the number of ways, except from a theoretical stand point the less the better. All crossovers create phase and therefore time shift and disconnect fundamentals from their harmonics. Crossovers are therefore a significant trespass.

I personally believe that if a sub is used their is no imperative for a three way speaker unless there are very high power demands.

In addition with driver selection it is possible to keep the crossover at 3 KHz and above. I have a design on the books, that I don't know if I will get to build, that crosses at 4KHz and only has three components in the crossover. It models really well.

I try to keep my crossovers acoustic as far as possible and not acoustic. It is pretty much impossible to avoid timing problems, however I like to minimize them as much as possible. This makes for speakers with superior sound stage in my view.

 

[lovinthehd]

I'd sure like to hear the bass performance of TLS's system compared to mine but in the meantime I'm pretty sure mine out performs his, crossover issues or no.

 

[Verdinut]

Sorry to disappoint you but this 4" driver is a very pleasant listen, especially in TL. It has a surprisingly good bass response down into the 40 Hz range and no sudden break up modes. It has good performance to 20 KHz..

It is the Jordan Watts modular driver, which appeared on the scene in 1959.

It was the brain child of Ted Jordan. A brilliant designer and mathematician. It is a spun aluminum cone that is a geometric tractrix. There is no sudden break up mode, and the radiating area progressively decreases with frequency. That results in good performance on and off axis.

The suspension is unique, using Beryllium cantilevers which also act as the lead in wires.

These units make a wonderful center in a small sealed enclosure crossed at 90 Hz.

I don't think there is anything hard and fast about the number of ways, except from a theoretical stand point the less the better. All crossovers create phase and therefore time shift and disconnect fundamentals from their harmonics. Crossovers are therefore a significant trespass.

I personally believe that if a sub is used their is no imperative for a three way speaker unless there are very high power demands.

In addition with driver selection it is possible to keep the crossover at 3 KHz and above. I have a design on the books, that I don't know if I will get to build, that crosses at 4KHz and only has three components in the crossover. It models really well.

I try to keep my crossovers acoustic as far as possible and not acoustic. It is pretty much impossible to avoid timing problems, however I like to minimize them as much as possible. This makes for speakers with superior sound stage in my view.

I was saying that a single cone driver cannot reproduce the full audible frequency range down to 20 Hz. You need a good woofer or a subwoofer to reproduce those low frequencies. It's a question of pure physics.

In addition, a 4" speaker is unable to put out the dynamic volumes required by today's recordings. I just don't believe it.

I had seen that Jordan Watts speaker many years ago in an ad. However, I am curious to know why that transducer hasn't been more popular on the hi-fi market. Was it because of its price?

 

[TLS Guy]

I'd sure like to hear the bass performance of TLS's system compared to mine but in the meantime I'm pretty sure mine out performs his, crossover issues or no.

That is very unlikely.

This is the FR and impulse response of the dual TLs.

Note the very extended bass response and smooth mid band. The HF droop above 15 KHz is due to the response of the measuring mic. The tweeter is flat to 20 KHz.

The impulse response is truly exceptional, showing proper damping of the lines and good time response. The bass is not only extended, by extremely powerful and clean and can really punch you in the gut. It also can realistically reproduce the lowest organ pipes even when just played extremely softly. The realism is complete.

This is a picture of the one of the triamped dual transmission line speakers.

However is not the spl so much as the sheer accuracy of these speakers, especially the bass that sets them apart.

Engineers have been making the 200 mile plus journey from Minneapolis to check mixes on these speakers and master CDs with them. The bass accuracy is something they really value.

One engineer who is also a music professor and percussionist, says these are the only speakers he has ever heard that reproduce drums with total accuracy. He has expensive Genelecs in his studio.

Unfortunately few have heard a properly designed and set up TL system. As far as I know, the late John Wright of TDL and myself are the only individuals to have designed dual folded TL speakers.