@tmuikku
This! Exactly this. You presented it very well in your response. As long as the driver has enough displacement to cover that, as cone excursion will be higher than usual, it is doable. Now the strain on the cone and speaker will still be big, and one has to cherrypick a good driver, and distortion rises with excursion, so it is not a free lunch. But the price to pay is arguably lower than the alternatives.
//I mentioned impedance shaping in my post, and I see how it can be easily overlooked. I would do that too. "Impedance shaping, yeah, right, next...". But in this case it is quite crucial part of the problematics.
This! Exactly this. You presented it very well in your response. As long as the driver has enough displacement to cover that, as cone excursion will be higher than usual, it is doable. Now the strain on the cone and speaker will still be big, and one has to cherrypick a good driver, and distortion rises with excursion, so it is not a free lunch. But the price to pay is arguably lower than the alternatives.
//I mentioned impedance shaping in my post, and I see how it can be easily overlooked. I would do that too. "Impedance shaping, yeah, right, next...". But in this case it is quite crucial part of the problematics.
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With some types of music with compressed sine wave like waveforms the lack of cone movement can be a problem, but most music has a wide mix of frequencies that will pump heat from the coil.
Yes, there is a tendency for people to become single minded in whatever they believe to be the best, excluding facts that contradict their beliefs.
The 35Hz Fb TH thingie requires considerably less voltage to reach Xmax in the 45 Hz range than the 28Hz Fb BR, 87v compared to 108v.
Given 120v, it's upper range output could exceed 130dB.
In the low end, I'd think the TH would keep up to the pair of BR, in the upper end, the BR pair would have a +3-4dB advantage.
Depending on the program material, the single TH may "keep up" with a pair of BR.
For maximum power density and (arguably) sound quality, BR will beat TH.
For low frequency output/cost, the TH have an advantage.
Art
Indeed. This is highly dependable, and that needs to be taken into account too. Great point I was thinking about, but not mentioning it.
My kind of music is heavy and bass heavy. Some tracks even having only 4dB dynamics, suprisingly in chillout psybient, no trance or techno. Modern chill can be suuuuper demanding. Who would have thought.
Yes, TH can hold its own, and in some cases be better. No denial here. And it wins big time in efficiency and price per decibel. But the mood now is that TH will outdo two very strong ported bins in the same volume across the board and across all disciplines, and it is really load of nonsense. "May keep up" is exactly the fair evaluation for it. You don't hear that from "TH people".
I did build few TH's and they have their charm and magic. Sure.
I did my own sims, and usually ended up within the TH performance, but advantageous on power compression and being more modular and mobile. On the other hand, significantly more expensive.
I suspect another advantage though, and I am going to test it too. As the drivers only work around the impedance peak, the amplifier sees range of 10-100 Ohm loads.
Simply put, 8Ohm amp at 1800 Watts, being stable at 4Ohm (but not reliable) should be reliable to drive two of these drivers in parallel, nominally as 2x1800Watts.
If that's the case, that's some savings back.
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Now, I put that TH in the sims too. When I EQ things out for the same acoustical performance of the 28Hz ported bin, it doesn't run that far from the small single bassreflex. It clearly can do a lot more, obviously, but it can't do 6dB more even in the wildest dreams, to match the two ported bins. And eating 800 watts at 70Hz with no excursion is not going to help either. 🤭
Anyone have a link to a good example of the compressed wave shapes in music (as compared to something without that issue) I can try on my junk? 🙏🏻🙏🏻
Here is the TH comparison in Hornresp, after we EQ it out for usable response, and add thermal compression.
Top row is the TH, bottom row is BR:
The bassreflex power scales well with excursion. At 34.7Hz, quite weak point, the power is 825Watts and 7mm of cone excursion.
With TH, we have 1290Watts at 70Hz and 1,2mm of excursion, and it arguably gets worse upper in the range.
Now, let´s ignore that, and imagine that with dynamic music, the driver will not burn. It is perfectly reasonable in many cases.
Now, who believes we can add 6dB of input power and have clean 6dB of ouput SPL with no losses to match two of these ported bins.
Can´t stop grinning. I´m giving that box solid three minutes before it goes...
My guesstimation is to put that thing +3dB, get 2dB back on the output side. Dial back the BR -0,5dB to stay withing excursions limits.
Two ported bins going 3,5dB louder, exactly in the middle of weltersys´s estimation. But I am really giving it here to the TH.
Top row is the TH, bottom row is BR:
The bassreflex power scales well with excursion. At 34.7Hz, quite weak point, the power is 825Watts and 7mm of cone excursion.
With TH, we have 1290Watts at 70Hz and 1,2mm of excursion, and it arguably gets worse upper in the range.
Now, let´s ignore that, and imagine that with dynamic music, the driver will not burn. It is perfectly reasonable in many cases.
Now, who believes we can add 6dB of input power and have clean 6dB of ouput SPL with no losses to match two of these ported bins.
Can´t stop grinning. I´m giving that box solid three minutes before it goes...
My guesstimation is to put that thing +3dB, get 2dB back on the output side. Dial back the BR -0,5dB to stay withing excursions limits.
Two ported bins going 3,5dB louder, exactly in the middle of weltersys´s estimation. But I am really giving it here to the TH.
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Your charts show the TH has an easy +6dB more output left in the 40Hz range, using well under half the excursion and power of the BR.
While the single TH would keep up in the lower frequency range, two BR would have more output potential above.
That said, the TH is undersized 😉
Try skarlxrd phonk mixes. Could have been interesting music if it wasn't often distorted or compressed.
@weltersys
No it doesn't? 40Hz is not an isolated point in real world. +6dB is double cone excursion. We are talking about 16mm here at 42Hz, which is out of drivers specs. You are stacking advantages on top each other like its noones business, but that's not how it works. What are we supposed to do with 40Hz performance when we don't have much left at 42Hz? That's the unreasonable part. The TH might be undersized, so is the ported bin. Then we would be comparing these LF21N551s in 130l bins instead. Also, if you can ignore anything, so can I, to tune the ported box to 40Hz, and now I am within its cone excursion limits too, and can add imaginary decibels too. This leads nowhere if we have no standards here.
No it doesn't? 40Hz is not an isolated point in real world. +6dB is double cone excursion. We are talking about 16mm here at 42Hz, which is out of drivers specs. You are stacking advantages on top each other like its noones business, but that's not how it works. What are we supposed to do with 40Hz performance when we don't have much left at 42Hz? That's the unreasonable part. The TH might be undersized, so is the ported bin. Then we would be comparing these LF21N551s in 130l bins instead. Also, if you can ignore anything, so can I, to tune the ported box to 40Hz, and now I am within its cone excursion limits too, and can add imaginary decibels too. This leads nowhere if we have no standards here.
True, if you want to compare real world performance, the Fb should be matched, as I did when comparing the 18SW115-4 in a TH to a "full sized" BR.
And actual, rather than simulated excursions should be measured, as Hornresp assumes both Bl and suspension to be linear, while they obviously are not.
https://www.diyaudio.com/community/threads/tapped-horn-vs-bass-reflex-case-study.184992/
In that comparison, a pair of BR have a low frequency advantage over the TH, while the single TH has a similar upper advantage.
Of interest, at high drive level, the BR lost LF output due to "port compression" relative to upper level. The TH didn't suffer from any "port compression", but had more upper pass-band "power compression" than the BR, effectively making the response more similar.
Anyway, for those that can afford double the drivers and amplifiers, the BR are a better choice.
Art
Qts is .3 or lower closer to .2 in this case.
Most people are familiar likely with woofer Qts of .4 to .6
This case yes Qts is total quality of driver. Is a combination
or mechanical and electrical properties.
With heavy cones and somewhat tighter suspension for efficiency.
It is basically telling you the motor itself is very very powerful motor.
Higher Qts woofers will usually need much larger boxes.
And highly unlikely to reach a flat alignment regardless
without a much larger box. So box volume is also likely to be close
or even larger than Vas. What your use to seeing
Low Qts driver will use a smaller box.
Once you start seeing large 15" to 18" drivers with very low Qts
below .4 or .3
It is more optimized for Horn Loading AKA bandpass.
optimized Compression chamber for horn loading or bandpass will usually be much smaller
than Vas volume
Of course you can put a low Qts driver in reflex.
The box will be much smaller, which people like.
As you will find for " Un Assisted" alignment they tend not to make much bass.
From Hi Fi to live audio its usually the problem.
Most assume " Un Assisted" but in real life they will
be assisted regardless depending on listening levels with basic shelf filters
or array of peaking filters.
Kinda I agree with low tuning.
It is problem with sim and people looking at graphs.
The main word here is Transient and accuracy.
And the higher you tune the worst it is. It is that simple.
Impedance curve is ignored and transfer function get over thought.
Nobody seems to take the Two impedance peaks fH and fL
and more important the Dip Ro or impedance at fb
Everything is OVER at the first peak.
And basically Ro dictates where transient is basically no more.
Ports have no Wires to them.
The energy comes from the speaker and actually electrical energy.
Once you dedicate more output to the port.
The accuracy or actual real reproduction of signal is LOST
to make the port go puffy puffy. The cone stops moving less as the port conducts more.
Again people worry about 2 dB of port in a Half Space transfer function.
When real world a EQ will add as much as you want.
agree Its hilarious when people say tuning higher is less cone excursion
lets unload the system at 40 Hz instead of 30 Hz lol.
The cone moves less above fb because it is putting more into the port
AKA no accuracy.
Funny you find the 606 redundant but it is exactly what you are doing.
The EV drivers where .3 Qts so they went into 3 cubic foot boxes
as compared to 4 or 5 cubic foot boxes to get good transient response.
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@weltersys
I have read that in past. There is good merit to that, but also there is caveat to that comparison. The use case was "quite large" ported box, and it deserved different driver to make maximum from the volume, if we are comparing SPL density. Putting 21DS115 in such volume would change things. Now it is not fair, but the argument is about SPL density possible to extract from the volume in this case. Once we cut off the frequency response for sub use at 85-90Hz, some more upper range advantage of the TH vanishes. But I get that it is a case study, not a broadscale SPL density study, and asking for it might not be humble either.
In past though, the mood was so strong about this, that no side wanted to acknowledge that:
A) TH is superior solution to bassreflex "per driver" for the needs of overwhelming majority of users..
B) Ported design is capable to outdo TH per volume.
I guess we settled this, and it would be wise to continue on the constructive note.
There are new fights between ROAR and Paraflex people, I am surprised that Superscooper thingie still isn't settled after those years.
I have read that in past. There is good merit to that, but also there is caveat to that comparison. The use case was "quite large" ported box, and it deserved different driver to make maximum from the volume, if we are comparing SPL density. Putting 21DS115 in such volume would change things. Now it is not fair, but the argument is about SPL density possible to extract from the volume in this case. Once we cut off the frequency response for sub use at 85-90Hz, some more upper range advantage of the TH vanishes. But I get that it is a case study, not a broadscale SPL density study, and asking for it might not be humble either.
In past though, the mood was so strong about this, that no side wanted to acknowledge that:
A) TH is superior solution to bassreflex "per driver" for the needs of overwhelming majority of users..
B) Ported design is capable to outdo TH per volume.
I guess we settled this, and it would be wise to continue on the constructive note.
There are new fights between ROAR and Paraflex people, I am surprised that Superscooper thingie still isn't settled after those years.
At no point a driver with stronger motor, actually outputting more Newtons per Watt at the cone, makes less bass. It is a big misunderstanding from leaving things unmanaged.
Also their set of parameters suited for horn loading is half way accidental. You don't want to put a driver with @40mm long coil that will not move that much in a restricted closed chamber of a horn. That will end up badly. The driver has different, either own or "tightly" chosen purpose, and is not to be used in random designs because it seems to fit based on small signal parameters.
For the previous discussion and the 606, that is just general feeling, not real consensus. I am still learning, testing, developing, simulating, comparing etc.
For me, I don't care about SPL volume density, and I do care about maximally flat extension, as low as I can go.
So I go with big reflex box volume and big long ports.
This is for recorded music playback at home, both indoors and out, often at high SPL.
For live----I dunno, I just can't see a real good case for small reflex boxes. If they are singles, must pack a few.
If doubles, might still need to pack, so why not go ahead and add some volume and ports. All assuming one wants to stay with reflex.
@mark100
Indeed to each his own. There are quite a few downsides to my choice, or at least compromises. I can´t deny that.
The reason I do this is so it is not intrusive, is not taking much space, and if everyone decides to ignore me or gets too high, I can pack the PA by myself without back pain. Also, I do not do regular gigs. I am building four bins. Except for low-end extension, one is already borderline overkill, or at least very nice solution to my needs. Four, that´s just for twice a year to be VERY happy with outside music and being sure nothing is cooked.
Now, flat extension is a spicy topic. Once we have DSP at hand, that can straighten it all out, then what´s the problem.
Now if you put a speaker in a large volume box, why the heck would ir suddenly be somehow wrong, if you put stronger motor speaker in the same situation?
I fail to grasp that concept, that when you have a speaker with more available motor force in the box, suddenly it is wrong.
Does not make even a bit of sense and has no logic, IF you have DSP to solve its differences in the response.
Live in my case means synthetic, heavy bass. Quite few tracks I like have even just 4dB dynamic range. For that reason, having more motors, coils and cooling area helps tremendously to avoid problems. Also as it is power dense, it is rather heard than seen. These can sit under the table, and these will do a lot of "damage" for a rig that is barely visible. I like that idea.
Indeed to each his own. There are quite a few downsides to my choice, or at least compromises. I can´t deny that.
The reason I do this is so it is not intrusive, is not taking much space, and if everyone decides to ignore me or gets too high, I can pack the PA by myself without back pain. Also, I do not do regular gigs. I am building four bins. Except for low-end extension, one is already borderline overkill, or at least very nice solution to my needs. Four, that´s just for twice a year to be VERY happy with outside music and being sure nothing is cooked.
Now, flat extension is a spicy topic. Once we have DSP at hand, that can straighten it all out, then what´s the problem.
Now if you put a speaker in a large volume box, why the heck would ir suddenly be somehow wrong, if you put stronger motor speaker in the same situation?
I fail to grasp that concept, that when you have a speaker with more available motor force in the box, suddenly it is wrong.
Does not make even a bit of sense and has no logic, IF you have DSP to solve its differences in the response.
Live in my case means synthetic, heavy bass. Quite few tracks I like have even just 4dB dynamic range. For that reason, having more motors, coils and cooling area helps tremendously to avoid problems. Also as it is power dense, it is rather heard than seen. These can sit under the table, and these will do a lot of "damage" for a rig that is barely visible. I like that idea.
Yep, each to own for sure. And subs sure can be a pain when it's just us.
Yep again, I almost always go for the most BL^2/Re i can get....even for lows and mids....
Also however, I do my best to let the box do the heavy lifting...not the DSP. (I am not a fan of low end EQ boost.)
Here's my latest big reflex, measured raw on driveway, with no DSP other than a LR24 low-pass @ 120Hz.
The low-end belong to the box 🙂 (it is a big sucker though.....see my "V-Twin" thread
NOICE. Well "most Bl^2/Re one can get does not get that easily flat. What setup do you have there? I mean, speaker too.
I also would be curious about this. Yes, we can fix the frequency response, but we can't modify the impedance response with DSP and different box sizes results different impedance responses. I don't know this latter is the reason of the wrongness (is it wrong at all?) of a strong motor in a large box.
A larger box leads to a higher electrical impedance response in general (but the higher frequency impedance peak goes lower in the spectrum), the valley caused by the port tuning becomes narrower. I don't see why this could be wrong.
On the contrary, the woofer in the larger box needs less electrical power for the same bass SPL than in a smaller box, this is always good IMO.
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To date, the arguments are:
1) Frequency response plot that is not flat anymore. Relevant for some, irrelevant for some.
2) Low efficiency (debunked).
3) Excessive power after EQ (debunked).
4) Underutilisation of the driver. That is true, but who drives his car at full speed all the time in order for the motor to be fully utilised?
After all, it is hypothetical. If we take a real driver, we find out that some questions disapper for irrelevance for different reasons. For example if we take B&C 18DS115, we find out that the suspension is stiff and additional efficiency is almost as good as gone.
1) Frequency response plot that is not flat anymore. Relevant for some, irrelevant for some.
2) Low efficiency (debunked).
3) Excessive power after EQ (debunked).
4) Underutilisation of the driver. That is true, but who drives his car at full speed all the time in order for the motor to be fully utilised?
After all, it is hypothetical. If we take a real driver, we find out that some questions disapper for irrelevance for different reasons. For example if we take B&C 18DS115, we find out that the suspension is stiff and additional efficiency is almost as good as gone.