Fot the car analogy: this car (speaker) can go over 60km/h and you don’t even get punished for it if you push it, just to be sure the neighbors are not at home. 🙂
This speaker is not like a 2000HP race car, it's more like a 3-400HP car from everydays.
Anyway, the problem with all analogies is that it is just a similarity and not an identity.
This speaker is not like a 2000HP race car, it's more like a 3-400HP car from everydays.
Anyway, the problem with all analogies is that it is just a similarity and not an identity.
I'm starting to think a lot of people or just me, do not understand system sensitivity very well....
Each driver in this design is pretty high sensitivity....the woofer is 99db, and the mid woofer is 96db...while the tweeter is 110db....
System Sensitivity means little to me unless its showing an underlying driver issue.....unless somehow the designer found a way to reduce woofer efficiency....Sensitivity is tied to efficiency but isn't tied to excursion efficiency if the crossover is the catalyst for its change....efficiency of the input level may change but not the woofers mechanical efficiency....so as long as there is enough amplifier power...what care is it if the system Sens is 92db or 96db.....the sound quality is tied to the efficiency of the woofer.
You may already understand this and trying to say something else that I don't understand? If we had two systems with identical Sensitivity but one with much more efficiency than the other....they are not acoustically the same....
If we had two systems with matching efficiency and one system has significantly higher sensitivity...acoustically, they should be identical..
Good point camplo, furthermore the woofer is crossed actively which is better for efficiency than passive. Even with 92dB/2.83V mid-high section, this is a high efficiency speaker, because the impedance is relative high too. Normal commercial home speakers rarely reach that efficiency level.
But on closer inspection, however, it can be seen that the final combined impedance is not as high as I assumed, mainly due the shunt resistors.
The passive crossover (mainly the resistors) appears to be the limiting factor in the maximum sound pressure of this speaker.
The passive crossover (mainly the resistors) appears to be the limiting factor in the maximum sound pressure of this speaker.
The comments in this thread are interesting...
No design is perfect and all designs are compromises... Or we wouldn't be here. I am not sure why Troel's designs are put on a pedestal to be over judged. Particularly when he brings so much to the community.
Some of the perplexing comments:
"The bass driver isn't big enough to justify it being part of the loudspeaker range" to "all could be done with a 8" woofer".
The latter is madness (I'm surprised no one has responded to this) and clearly demonstrates the risk of believing everything on the internet - as they cannot of ever heard a big SD woofer in a large multiway. *facepalm*
"Troels uses expensive crossovers, hybrid topology (active and passive) should be fully active etc"
So what.. It's his design and it's his compromises. He has a variety of designs, must be over 100 now.
There is enough insight, that you could recreate it actively without paying him a dime. Only effort is to build the cabinet and fine-tune the active crossover. This is all preference though and design decisions that come with compromises. Doesn't make a speaker null and void.. I prefer fully passive as I like to roll dacs, so this wouldn't be a speaker for me but I do like some of his other designs.
The final point is the assumptions. Do we know he hasn't measured dispersion between CD/Horn to Mid-Woofer? Troel's doesn't contribute here, so if you are going to comment on a design - then at least have clarity. I think this is important in a pandemic, where many are struggling. It is unfair, to throw around unsubstantiated claims at peoples livelihoods.
The only person, who had actually mentioned they've listened to a number of his designs including one similar to the one in this thread.. Was shafted as Troels himself or his biggest fan LOL.
Diyiggy - I have had the opportunity to have a few months with the TL2. If you want feedback on how the presentation compares to a BE Dome drop me a pm 🙂. They're very different, both with their pro's/cons and very clear tradeoffs.
No design is perfect and all designs are compromises... Or we wouldn't be here. I am not sure why Troel's designs are put on a pedestal to be over judged. Particularly when he brings so much to the community.
Some of the perplexing comments:
"The bass driver isn't big enough to justify it being part of the loudspeaker range" to "all could be done with a 8" woofer".
The latter is madness (I'm surprised no one has responded to this) and clearly demonstrates the risk of believing everything on the internet - as they cannot of ever heard a big SD woofer in a large multiway. *facepalm*
"Troels uses expensive crossovers, hybrid topology (active and passive) should be fully active etc"
So what.. It's his design and it's his compromises. He has a variety of designs, must be over 100 now.
There is enough insight, that you could recreate it actively without paying him a dime. Only effort is to build the cabinet and fine-tune the active crossover. This is all preference though and design decisions that come with compromises. Doesn't make a speaker null and void.. I prefer fully passive as I like to roll dacs, so this wouldn't be a speaker for me but I do like some of his other designs.
The final point is the assumptions. Do we know he hasn't measured dispersion between CD/Horn to Mid-Woofer? Troel's doesn't contribute here, so if you are going to comment on a design - then at least have clarity. I think this is important in a pandemic, where many are struggling. It is unfair, to throw around unsubstantiated claims at peoples livelihoods.
The only person, who had actually mentioned they've listened to a number of his designs including one similar to the one in this thread.. Was shafted as Troels himself or his biggest fan LOL.
Diyiggy - I have had the opportunity to have a few months with the TL2. If you want feedback on how the presentation compares to a BE Dome drop me a pm 🙂. They're very different, both with their pro's/cons and very clear tradeoffs.
"There is enough insight, that you could recreate it actively without paying him a dime. Only effort is to build the cabinet and fine-tune the active crossover. "
But who wants to copy such an ugly cabinet? Of course that's a matter of taste and function is the first thing but that horn-umbilical takes everything (that's why Troels suggests the grills? 🙂 ). But maybe this cake still tastes good to someone, we don't know. 🙂
But who wants to copy such an ugly cabinet? Of course that's a matter of taste and function is the first thing but that horn-umbilical takes everything (that's why Troels suggests the grills? 🙂 ). But maybe this cake still tastes good to someone, we don't know. 🙂
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that's a good point. I wanted more to understand about the physical arrengement between the mid and the horn/tweet vis à vis of the crossover as well, but the thread turned out in several directions, all are interresting.
Don't hesitate to write the trade ff you found here 🙂 .
Don't hesitate to write the trade ff you found here 🙂 .
Troels put the horn below the mid to get the desired time alignment to the listening position and maybe for more easy crossover work and maybe the midrange driver had the best response at that position on the baffle.
Any chance you could share pros/cons here be please? Id be interested to read about them too. Which tweeter option on the TL2 you have listened to? Which BE dome? The one used in Troels 3WC-15?
Cheers!
If a speaker with all-passive filters has flat SPL response, its overall sensitivity will be limited by the driver with the lowest sensitivity. In almost all cases, the limit will be the bass driver (woofer). The bass sensitivity / efficiency is determined by the size of the woofer / box and the bass cut-off frequency. For high sensitivity / efficiency, the speaker must either be large, or must have high cut-off, or a bit of both. It is up to the designer to choose the right compromise between sensitivity/efficiency, size, and bass extension.
High sensitivity / efficiency is important in home "Hi-Fi" systems if a low-power amplifier is used (small tube amps, class-A amps, etc.). This is why "weak" amps typically go well with large speakers, and vice versa.
The motivation to sacrifice a lot of real estate for a large "Hi-Fi" loudspeaker in a home environment is almost always due to the need for high sensitivity / efficiency, i.e., if a low-power amplifier is used. With a high-power amplifier, there is no need to use a high sensitivity / efficiency loudspeaker, so it can be smaller and still produce deep bass.
Troels "Loudspeaker III" is a large "Hi-Fi" loudspeaker (as far as I can tell it's not intended for PA use or other non-home or "no Hi-Fi" applications). Therefore, one might think it's large because the designer chose the size/efficiency/bass-extension compromise in this way in order to get a high sensitivity/efficiency speaker with decent bass extension.
However, Troels decided to run the woofer from a dedicated, powerful amplifier. This removes the sensitivity/efficiency limitation of the woofer, because the gain of the bass amplifier can just be cranked up to pretty much any level that is required to match the passive mid / tweeter. Also, the active filter in the bass amplifier can be set to boost the deep bass to get flat bass down to 20 or 30 Hz without trouble, so the limitations on the bass extension of the loudspeaker system are also removed.* This means that two major reasons for choosing a large woofer in a big box melted into thin air when Troels decided to use a dedicated amp for the woofer.
I hope all this explains why I don't understand why Troels made this speaker so big, and still gets so little sensitivity / efficiency out of it.
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(*) Active systems also have their limits in terms of size and bass extension, but they are still in a very different league than a passive system.
Actually there isn't really, and that is why all the questions come. If you compare his designs with, say Zaph (before he went commercial) you can see with a Zaph design he puts a lot of the reasoning in. BUT Zaph tended to use off the shelf cabinets whereas Troels appears to be a fairly good carpenter (I'm lousy so can't tell). He also appears to be somewhat addicted to designing speakers. Certainly keeps him out the pub!
I should note I have no beef with Troels as a person, but his stuff is not for me because the cabinets are too complex for me to built and I'm not good mates with a cabinet maker and I go active so I'd have to reverse engineer the crossover from scratch. I understand why he does this and that is his choice but I would personally rather build something described in detail on here if I ever get to that point.
Most of Troels designs with the Hypex Plate amp use the high level inputs so the input to the plate amp is the speaker level output. This is done to allow a stereo DAC and amp to drive the whole speaker, so you could roll as many DAC's as you like 😉
Ultimate SPL level at bass frequencies is determined by Volume Displacement, how much air can the driver(s) move.
15" Woofer 15W700 Sd 850cm2 xmax 6.5mm
8" Subwoofer SB23MFCL Sd 210cm2 xmax 12mm
850 x 0.65 = 552.5 cm3
210 x 1.2 = 252cm3
If you then compare these numbers to a volume displacement chart (below) you can see how loud each can get at what frequency (The chart is for a sealed system as it is the one I have saved but it works for comparison purposes).
This means the large driver has to use a quarter as much excursion to get to the same SPL. More Sd and less excursion makes a lot of sense to me.
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How much degrees of cycle can be "won" in the high pass filter by putting the tweeter below the mid, please ?
Not sure where the acoustical center of a combo cd/horn is ?
Not sure where the acoustical center of a combo cd/horn is ?
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Maybe the 8 " twoofer won't generate enough SPL ? 🙄
My home setup is 2 x18 " , 4 x10 " , and 2 x 8 " , and all listeners who have ever heard of it ever thought it was silly .....
I think you must know something about it ..........🙄
" Scrolling down the page here, some of you may start thinking JBL 4343, 4344 and 4345, and you're right. These studio monitors are my inspiration, and let's get to my main concern immediately, because the reason for holding back on such a construction is the issue of time-alignment of of midrange driver and the horn. "
" To time-align - or not time-align
Do we need to time-align the midrange and horn with steep slopes and a point of crossover around 1.2-1.5 kHz? Some will say yes, some may say it all depends. Fact is that these old monsters deliver an astonishing midrange/lower treble, regardless of the compression driver acoustically being some 10-15 cm behind the midrange driver. Doing dZ on the two drivers reveals the compression driver being 112 mm behind the midrange driver from mounted on a flat panel. With these date put into the simulation software, we can manage a flat frequency response from connecting the horn with opposite polarity relative to the midrange, where a 4th order filter would normally require same polarity.
There's the thing about frequencies in this range having a wavelength around 25-30 cm, close to the distance between our ears, thus making it hard for us the locate sound. Pay attention next time you hear a 1 kHz sine wave alarm tone - and you may experience how difficult it can be to locate the source. Thus, we may not notice the phase issues going on here. Now, the only thing to do is to set up the drivers on suitable baffles and make a crossover with a flat frequency response. Pulling the horn forward some 12 cm (about half the wavelength of the point of crossover) and connecting with the same polarity also made a flat response. Which one sounded the best? That was really, really hard to decide, because the horn to some extent would jeopardize the dispersion of the midrange driver unless they were wide apart. As always, any speaker is full of compromises. Numerous simulations were done, more than twenty, and some of them were set up for actual testing."
The-Loudspeaker
It's very new to me and not sure I understand assymetric XO and relation with time delay with passive filters... ANd I'm a passive filter guy cause I love diy dacs as I think there is a lot of headroom here also to tune the sound you like at home... And that's on axis 😀 don't ask me about all of that off axis for my basic thinking 
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!It is clear (when you read his website however not all here seem to do..) that Troels likes the impact that his high sensitive designs provide, especially in the bass department.
His first design, based on an 18 inch woofer, is an attempt to what can be done with a system with little compromise.
The other TL' s, based on 15 and 18 inch woofers, are attempts to what can be done in smaller enclosures.
The three-way classic designs are based on 12 and 15 inch woofers, and dome tweeters instead CD's.
It's the impact and the relatively low distortion of a large woofer, and I can understand (liked pointed out by member fluid above).
Yes, with a smaller woofer and DSP aided amplification you will have enough "bass", but it's just different.
It's also subjective, but I know what I prefer 😀
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The acoustic source differs from the timing reference and varies with frequency. Time aligning something like this in this way is questionable.diyiggy said:
