Bricolo said:
I guess that they both are ML TL... I showed the second one, as that is the one that the manufacturer recommends. I guess the next step is to listen to it and just try different configurations.
The cabinet looks different, since it looks short compared to my Peerless Pipes and Seas Thor TL. It will look much better when I add a 1.5" roundover.
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Brian
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I have been thinking about the BR and ML TL question all afternoon. I have no clue where the transition point is between the two designs. But the major difference is the constant pressure in the box for a BR helmholtz resonator and the standing wave with local pressure peaks in the long direction of the box for a ML TL. I have found that the amount of bracing needed for a ML TL is less because the pressure is local and for the first mode peaks at the top of the box where it is strongest. Also, in a ML TL damping is used which I believe helps with the leakage of higher frequency noise out of the port.
The point at which a BR becomes a ML TL is not clear to me. Again, I don't really think spending a lot of time trying to assign labels is worth the effort. If the simulation looks good then build the design and enjoy the results. If you realy want to be sure you have a ML TL make it tall. If you really want a BR make is almost equal lengths in all dimensions.
The point at which a BR becomes a ML TL is not clear to me. Again, I don't really think spending a lot of time trying to assign labels is worth the effort. If the simulation looks good then build the design and enjoy the results. If you realy want to be sure you have a ML TL make it tall. If you really want a BR make is almost equal lengths in all dimensions.
I've been thinking at another thing all the afternoon 
Most of the time, when you read an article about TLs, you hear about good bass, pure midrange, but the most spoken about is the extended bass.
Does it really have more low extension that a BR of the same wolume?
If yes, the transition from BL to ML-TL you're thinking about should appear on the graph, as an extending bass
Most of the time, when you read an article about TLs, you hear about good bass, pure midrange, but the most spoken about is the extended bass.
Does it really have more low extension that a BR of the same wolume?
If yes, the transition from BL to ML-TL you're thinking about should appear on the graph, as an extending bass
FWIW, I've been doing some distortion testing on my SS8554 ML TL. (You can see it in Martin's gallery).
SS8554 distortion products in a ML TL at 92 dB
This is very good. A solid 35 Hz tone, the 2nd and 3rd HD and IM products less than 3% and really, the absence of any significant higher order products.
It's always hard to throw a graph like this out, since it's a bit relative. But I can say this is quite good.
I will eventually have more and more coherent data on this.
In general, I usually get a lower tuning frequency for an ML TL vs a simple ported box-but the max SPL are in the same ballpark.
The real question is-comparing the distortion spectrum of an ML TL vs an identical driver in a typical BR.
SS8554 distortion products in a ML TL at 92 dB
This is very good. A solid 35 Hz tone, the 2nd and 3rd HD and IM products less than 3% and really, the absence of any significant higher order products.
It's always hard to throw a graph like this out, since it's a bit relative. But I can say this is quite good.
I will eventually have more and more coherent data on this.
In general, I usually get a lower tuning frequency for an ML TL vs a simple ported box-but the max SPL are in the same ballpark.
The real question is-comparing the distortion spectrum of an ML TL vs an identical driver in a typical BR.
You're right Dave,
Not all distortion sounds the same.
Consider the following two graphs
SS8554 at 96 dB SPL
SS8554 at 100 dB SPL
In both cases second order harmonic and IM products dominate. In the first the max is around 8%, in the second, around 10%. But, the audible difference is marked. In the second graph there are multiple higher order products and multiple IM products increasing-and this is audibly much worse than you might expect.
Not all distortion sounds the same.
Consider the following two graphs
SS8554 at 96 dB SPL
SS8554 at 100 dB SPL
In both cases second order harmonic and IM products dominate. In the first the max is around 8%, in the second, around 10%. But, the audible difference is marked. In the second graph there are multiple higher order products and multiple IM products increasing-and this is audibly much worse than you might expect.
As far as post #44.
If you're asking is there a theoretical reason why a TL alignment will always have extended bass-I'll have to defer to Martin on that.
As a practical matter, of the 3 ML TL's I've built, all 3 have a lower f3.
Not, absolute spl levels don't really change much, as I mentioned.
If you're asking is there a theoretical reason why a TL alignment will always have extended bass-I'll have to defer to Martin on that.
As a practical matter, of the 3 ML TL's I've built, all 3 have a lower f3.
Not, absolute spl levels don't really change much, as I mentioned.
I think you do get lower f3 than a BR design...but thats not the whole story. The bass you do get is incredible. I have built 2 TL's, one with an 8" and one with a pair of push-pull 5.25". I don't know the exact measured f3, but the bass is so....full. It is not boomy like a ported speaker. It is hard to describe, but that clean, unobstructive low end is addictive to say the least.
I would try modeling some designs with Martin's worksheets. After some trial and error tuning a system, you can compare the frequency response of ML and BR yourself. Don't forget about all of the other graphs too.
I would try modeling some designs with Martin's worksheets. After some trial and error tuning a system, you can compare the frequency response of ML and BR yourself. Don't forget about all of the other graphs too.
Transient response is represented by group delay, which is by definition the slope of the FR curve. So, if the roll-off of your TL is the same as the roll-off of a BR, then the transient response will be the same. The reason so many BR's sound bad is that they are designed to be flat to cut-off in some box design program. Once room gain grabs the FR, you wind up with a boomy, sloppy sounding speaker. There is a tendency to do the same with MJK's worksheets--flat FR right to cut-off, or worse, with a peak right at cut-off. This will lead to a boomy, poor transient response speaker.
Room gain must be considered in speaker design. Designing in a slower roll-off raises F3, but gives better group delay. This is one reason that "classic" TL's have such good transient response. But the, you pay dearly is box size. There is no free lunch.
Bob
Room gain must be considered in speaker design. Designing in a slower roll-off raises F3, but gives better group delay. This is one reason that "classic" TL's have such good transient response. But the, you pay dearly is box size. There is no free lunch.
Bob
This is also something that isn't 100% clear for me.
You're not the only one that adviced me a "smoother" rolloff, because of the room gain.
But is it always recommended, independently of the bass extention of the speaker, or it's recommended here, because the speaker I'm designing will go down (f3) approx to 35Hz and that at this frequency the room gain is important.
In other words, for a speaker that goes down to, say, 80Hz, do we also need this smooth rolloff?
You're not the only one that adviced me a "smoother" rolloff, because of the room gain.
But is it always recommended, independently of the bass extention of the speaker, or it's recommended here, because the speaker I'm designing will go down (f3) approx to 35Hz and that at this frequency the room gain is important.
In other words, for a speaker that goes down to, say, 80Hz, do we also need this smooth rolloff?
Bricolo said:I've been thinking at another thing all the afternoon
Most of the time, when you read an article about TLs, you hear about good bass, pure midrange, but the most spoken about is the extended bass.
Does it really have more low extension that a BR of the same wolume?
If yes, the transition from BL to ML-TL you're thinking about should appear on the graph, as an extending bass
I hope Mr King will have an answear
Bricolo,
You are looking for a yes or no answer which I really don't have.
If you take a driver that is suitable for a BR enclosure and design using the T/S type alignment tables available in the LSDC you will get a low end response that matches an electrical filter analogy. The bass response will follow a well known filter roll-off and exhibit 24 dB/octave below the cut-off.
If you use my MathCad worksheets, and design a system like Bob Brines describes that is 2 or 3 dB down at the cut-off you will get a very different low end response. I agree with Bob that the room reinforcement will bring up the sagging SPL just above the cut-off frequency and provide a nice flat bass response. This is a completely different design philosophy and I think it provides a lower cut-off for a given driver in most likely a bigger box then would be obtained using the T/S alignment tables.
The other advantage to using a taller ported enclosure that exhibits a standing wave is that fiber filling can be used to control the higher order standing waves and the leakage form the port. I think that the addition of fiber is a real benefit to ported enclosures.
I cannot provide hard and fast rules for when a design is a BR or a ML TL. Typically if it is tall with the driver near the top and the port near the bottom it is using a standing wave to produce the bass. You might want to try the Ported Box worksheet and see what happens as you move the port up or down. If moving the port does not change the response one bit then the box is probably acting like a Helmholtz resonator and is a BR. If moving the port changes the response then you are probably messing with the internal standing waves and it is a ML TL.
Again, I do not have any black or white answers. I wish I could sit here and predict all of the aspects of a design's performance and tell you exactly what approach produced the best of all worlds, but I can't. If I could this would also mean that we had exactly the same taste, system, room, and listen to the same type of music Design something, build it, learn what you like and don't like from that experience, and then start again. I don't see any short cuts.
You are looking for a yes or no answer which I really don't have.
If you take a driver that is suitable for a BR enclosure and design using the T/S type alignment tables available in the LSDC you will get a low end response that matches an electrical filter analogy. The bass response will follow a well known filter roll-off and exhibit 24 dB/octave below the cut-off.
If you use my MathCad worksheets, and design a system like Bob Brines describes that is 2 or 3 dB down at the cut-off you will get a very different low end response. I agree with Bob that the room reinforcement will bring up the sagging SPL just above the cut-off frequency and provide a nice flat bass response. This is a completely different design philosophy and I think it provides a lower cut-off for a given driver in most likely a bigger box then would be obtained using the T/S alignment tables.
The other advantage to using a taller ported enclosure that exhibits a standing wave is that fiber filling can be used to control the higher order standing waves and the leakage form the port. I think that the addition of fiber is a real benefit to ported enclosures.
I cannot provide hard and fast rules for when a design is a BR or a ML TL. Typically if it is tall with the driver near the top and the port near the bottom it is using a standing wave to produce the bass. You might want to try the Ported Box worksheet and see what happens as you move the port up or down. If moving the port does not change the response one bit then the box is probably acting like a Helmholtz resonator and is a BR. If moving the port changes the response then you are probably messing with the internal standing waves and it is a ML TL.
Again, I do not have any black or white answers. I wish I could sit here and predict all of the aspects of a design's performance and tell you exactly what approach produced the best of all worlds, but I can't. If I could this would also mean that we had exactly the same taste, system, room, and listen to the same type of music Design something, build it, learn what you like and don't like from that experience, and then start again. I don't see any short cuts.
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