Hi there,
I'm using (and loving) a pair of Lowther Acoustas with DX4 drivers. Although I personally actually rather like their bass, friends and family have criticised it as being a tad "polite". So, I am considering trying out a mono-sub in the middle.
So, here come the questions which I'd appreciate some views on:
1. According to various views I have seen on the web, combining lowther drivers with subs can lead to problems of relative speed. In other words, "legend" has it that most subs are not fast enough to match lowther drivers. Can anyone suggest a sub design that would be fast enough, other than a khorn which I can neither afford nor build with my limited wood-working skills (and which, in addition, would not really suit the room - need a centre mono sub ideally)?
2. Failing that, has anyone had experiences with using delays to match the speed of different drivers in a system? How do you do it and how much impact does it have on the sound?
3. I am keen to keep the signal that goes into the Acoustas cross-over free. Do you see any problems in the fact that certain frequencies will thus be coming out of both the sub and the main speakers?
Thanks!
Nikos
I'm using (and loving) a pair of Lowther Acoustas with DX4 drivers. Although I personally actually rather like their bass, friends and family have criticised it as being a tad "polite". So, I am considering trying out a mono-sub in the middle.
So, here come the questions which I'd appreciate some views on:
1. According to various views I have seen on the web, combining lowther drivers with subs can lead to problems of relative speed. In other words, "legend" has it that most subs are not fast enough to match lowther drivers. Can anyone suggest a sub design that would be fast enough, other than a khorn which I can neither afford nor build with my limited wood-working skills (and which, in addition, would not really suit the room - need a centre mono sub ideally)?
2. Failing that, has anyone had experiences with using delays to match the speed of different drivers in a system? How do you do it and how much impact does it have on the sound?
3. I am keen to keep the signal that goes into the Acoustas cross-over free. Do you see any problems in the fact that certain frequencies will thus be coming out of both the sub and the main speakers?
Thanks!
Nikos
I am curious to know what you mean by a slow driver. AFAIK that's a misnomer. I am wondering if what you're describing is the bloated sound that many powered woofers offer versus the less boomy sound offered by something like a PA driver.
Good question - I am not 100% sure myself to be honest...I have spent much time trying to figure out what this (which is based on comments and views I have seen on various sites and forums in the past during my research) means.
Eventually, I reached the conclusion that it is probably a contrast to the "direct" (again, given lack of a better word) sound that the Lowthers have compared to (the limited number of) other speakers I have tried. Ultimately, I had assumed that a delay between what comes out of the Lowthers and the woofer (albeit one of milliseconds) would occur.
There's an Aura NS 18" for sale in the classifieds that would be perfect. 🙂 A simple sealed enclosure is extremely easy to build, transient response and group delay would be fine...
Yes. You need some sort of external low pass filter on the sub.
Yes. You need some sort of external low pass filter on the sub.
A DX4 has a ~0.21 Qts, ergo at a glance your sub needs a ~0.2 Qts 'sub' driver in whatever Qtc sealed or ~aperiodic alignment that most closely matches the Acousta's roll off slope to blend well, i.e. freaking huge if you don't use a Linkwitz-Riley Transformed (LRT) sealed cab and even then probably still fairly large since multiple drivers will be required to get efficiency up enough to keep excursion well within Xmax.
I assume though that you're driving them with a high output impedance, so the driver's effective Qts must be calculated before designing the 'sub' system.
Now you know why most sealed, vented sub systems can't keep up with a 'fast' set of mains since folks typically use a single > 0.4 Qts low efficiency driver.
I may be missing something obvious, but ATM I can't visualize how adding a delay will help such a Qt mis-match. Delays are about matching up differing phase responses.
OK, then you'll need to bi-amp and low pass the sub separately wherever it blends the best with the mains.
GM
I assume though that you're driving them with a high output impedance, so the driver's effective Qts must be calculated before designing the 'sub' system.
Now you know why most sealed, vented sub systems can't keep up with a 'fast' set of mains since folks typically use a single > 0.4 Qts low efficiency driver.
I may be missing something obvious, but ATM I can't visualize how adding a delay will help such a Qt mis-match. Delays are about matching up differing phase responses.
OK, then you'll need to bi-amp and low pass the sub separately wherever it blends the best with the mains.
GM
I think you have the right drivers. If the box is sealed all the better but it needs to be a solid box. Then what your really need is something to flatten out the low frequencies. Low Q is great for control, speed, and output but really does require EQ and a amp with solid bass. If the amp is sloppy there is nothing you can do really. High gain amps with lots of feedback usually but not always have better bass. There are a few different ways to EQ, a second order high pass filter with a Q of 1.5-2 or so set to flatten the sub. Frequency of the filter will be near the frequency of the woofer in the the box, Fb. Good luck!
How about an infinite baffle sub, while we're throwing ideas around...
Is there any amplifier in particular you'll definitely be driving this with, or are you thinking of buying one...?
Is there any amplifier in particular you'll definitely be driving this with, or are you thinking of buying one...?
also, if you dont want any filtering of your main speakers you will have to keep the sub within 1/4wavelength within passband. If you filter low at say 90hz this is much less of an issue (0.95m 1/4wave)
Note that distortion wont be decreased too much if the main speakers are still outputting sub frequencies. if the Qts is low this is less of an issue however.
Re: 'fast' I think we are not talking about the rise time, that refers to the high frequency cutoff.
Instead we are talking about resonance after the initial impulse due to tuned pipes(ports)also spurious harmonic products,not just the fundamental tuning and perhaps resonating panels,higher up in frequency if the enclosure is large enough.
I cant remember the math for the high cutoff rate and effects on transient response. There was a site around with scans of some Olson acoustics graphs.
Note that distortion wont be decreased too much if the main speakers are still outputting sub frequencies. if the Qts is low this is less of an issue however.
Re: 'fast' I think we are not talking about the rise time, that refers to the high frequency cutoff.
Instead we are talking about resonance after the initial impulse due to tuned pipes(ports)also spurious harmonic products,not just the fundamental tuning and perhaps resonating panels,higher up in frequency if the enclosure is large enough.
I cant remember the math for the high cutoff rate and effects on transient response. There was a site around with scans of some Olson acoustics graphs.
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I would be looking to buy or build an amp for this and I should mention that I would not want to spend a huge amount of cash on that - £200-£300 max.
Thanks for all the suggestions to everyone btw.
The main thing is to ensure you have enough displacement. Ie woofer area x Xmax for desired SPL and cutoff
If you are listening to normal music at normal volumes you may get away with a few 12"s. It may be useful to find a woofer to test on sealed,open baffle etc and see what your ears think
AFAIK Bass sounds slow if you have an uneven frequency response with huge peaks in the lower octaves (like most of the cheaper home subwoofers feature, since it gives the impression of "more bass"). This leads to a longer decay time of the peaked frequencies, which we perceive as slow and boomy bass. I guess your lowther drivers have a very good frequency response and by this sound very clear and fast. Also, the lack of bass makes a system sound faster and punchier than the same system with added low frequencies.
I would go for a sealed enclosure, featuring a pro audio driver of high quality (like the ones from B&C SPEAKERS for example), as this is the most "stable" system in terms of possible peaks in the frequency response. Also, pro audio drivers tend to be build with a similar mindset as your lowther drivers, meaning they have pretty light membranes, strong motor systems and a focus on quality instead of marketing.
EDIT: Forgot to mention, that for the best results, the sub has to have its own amplifier and a parametric EQ, as the resonances of your room will mess up every subs frequency response. One has to make sure the room influences are countered with the eq.
I would go for a sealed enclosure, featuring a pro audio driver of high quality (like the ones from B&C SPEAKERS for example), as this is the most "stable" system in terms of possible peaks in the frequency response. Also, pro audio drivers tend to be build with a similar mindset as your lowther drivers, meaning they have pretty light membranes, strong motor systems and a focus on quality instead of marketing.
EDIT: Forgot to mention, that for the best results, the sub has to have its own amplifier and a parametric EQ, as the resonances of your room will mess up every subs frequency response. One has to make sure the room influences are countered with the eq.
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I guess I also want to ask what could "fast" mean? I'm not pooh-poohing the aural experience you are having (like I would things which can not be identified under the rules of this careful forum when done in strongly evaluative language) but puzzled over what it could mean in plain ordinary real-world-variable speak?
A bigger problem (and here I hope I am not being paradoxical about real-world-variable speak) is the (to me at least) authentic validity of the 400,000 Rule. Bottom Hz times top Hz. You can't have great sound with too much woof or too much tweet. No kidding. A lot of British speakers, even two-way systems, sound great because they stick to the rule, having neither excessive bass nor excessive treble.
You seem bent on moving the bass way down. Don't do it unless you also have plans for treble extension.
A bigger problem (and here I hope I am not being paradoxical about real-world-variable speak) is the (to me at least) authentic validity of the 400,000 Rule. Bottom Hz times top Hz. You can't have great sound with too much woof or too much tweet. No kidding. A lot of British speakers, even two-way systems, sound great because they stick to the rule, having neither excessive bass nor excessive treble.
You seem bent on moving the bass way down. Don't do it unless you also have plans for treble extension.
As I said before, although I am myself struggling with the terminology, I believe it refers to the "directness" of the lowthers.
For example, in addition to the Acoustas (which I am driving with a Rogers Cadet 3), I have a pair of FAR Acoustics studio monitor speakers. When doing A-B comparisons, in addition to notable differences in audible frequencies (the monitors lack mid-range detail and have more bass), there is a certain feeling of the sound being more direct or immediate with the lowthers. I know it's hard to describe in real English, but hope this gives a rough idea of what I mean (and what I feared, perhaps erroneously, would happen if I added a sub).
Regarding the 400,000 rule, this does not necessarily go against the idea of adding some bottom end. I never actually bothered doing proper measurements but "ear" tests using frequency sweeps did confirm a skew towards upper frequency extension.
Finally, I should stress that I am not at all bent on taking the bass down - I am just considering it as an option as a result of comments by a few different people that listened to my system and always with a view to experiment. If I try it and it doesn't sound good, I will have no qualms about getting rid of it all!
FAST--- Back when I was a manufacturer a dealer called up one day and said, "I have hooked all my different amplifiers to this subwoofer and watched the cone. With every other amplifier the cone just vibrates. With your amplifier the cone jerks around. It will jump forward, stop, and then jump back. All the other amps the cone just moves smoothly back and forth." I said 'So which has the better bass?" He said "Your by far has more impact and definition than any other."
My conclusion... the amp is at least partially responsible for the sound of the bass. Floppy sounding amps are just floppy sounding and solid sounding amps well...
=SUM
My conclusion... the amp is at least partially responsible for the sound of the bass. Floppy sounding amps are just floppy sounding and solid sounding amps well...
=SUM
Hello,
main reasons for slow bass are:
Any given speaker creates a signal-depending load on an amplifier, depending
on the the music signal, the more complex, the greater are the feedback to the
amplifiers, with negative implications on the signal processing.
The IMP is very important
and
The inertia of the a heavy membrane slows the music signal down and this is especially
noticeable on lower sound levels, typical for a normal living room, where the larger
the mass of the membrane, the more it will dampen the signal, which is the main reason
for the serious lack of bass resolution in heavy bass membranes.
may be helpful for understanding: translation needed
Ein wenig Theorie zur Basswiedergabe
main reasons for slow bass are:
Any given speaker creates a signal-depending load on an amplifier, depending
on the the music signal, the more complex, the greater are the feedback to the
amplifiers, with negative implications on the signal processing.
The IMP is very important
and
The inertia of the a heavy membrane slows the music signal down and this is especially
noticeable on lower sound levels, typical for a normal living room, where the larger
the mass of the membrane, the more it will dampen the signal, which is the main reason
for the serious lack of bass resolution in heavy bass membranes.
may be helpful for understanding: translation needed
Ein wenig Theorie zur Basswiedergabe
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"hm" has spent a lot of energy making horns for bass and the page referenced discusses his analysis of bass.
As frequency increases radiation resistance also increase as the square of the frequency which is why a 1 inch tweeter will play as loud in its passband as an 18 inch woofer in its passband. From a mechanical analysis standpoint of first approximation all direct radiator transducers for audio are second order low pass systems which show linear motion response below resonance and roll off at -12dB per octave above resonance. This roll off effect above resonance is the region we use drivers because that matches up with the radiation resistance to give a flat acoustic response, more of less, in the acoustic passband. What does this mean? In reference to driver size and frequency the acceleration and acoustic load of the driver increases with higher frequency. A larger driver moves less distance to make the same SPL and therefore experiences lower acceleration for the same SPL. Fast is not maximum speed, FAST is acceleration. As on "hm" web page the conclusion that a more powerful motor (all other things being equal) will always be faster is true. This is why I like the biggest magnet there are with the higher resistance voice coil because that leads to the most powerful motor. Then there is the part about the heavy cone on "hm" web page. While it is clear given the same force a heavier cone will accelerate more slowly is absolutely true however, if that light cone bends and flops around it just does not matter. The cone needs to behave as a unit and move as one piece and not flop like a fish out of water. To achieve that a very rigid and well damped cone is needed. This then means a big magnet and powerful motor is also needed. Floppy and sloppy are easy and cheap. Solid and powerful are not cheap in drivers or in amplifiers usually.
The drivers the starter of this thread is using are very good IMO. He just needs to EQ the drivers for flat response and his "slow polite" bass will turn into to gut punching bass.
Resonance peaked bass response as is so very common and the heart of ports is a big step in the wrong direction because resonance peaking means to store energy. Storing energy is good for making sine waves but is not worth a darn for transient response. No one ever talks about the FACT that the radiation from a port is one full cycle behind the active driver. Lousy for transients but good for making continuous sine waves. Best impulse response is clearly with a Q in box of 0.577 Bessel response as often defined in filter theory. The thread starter has a system very much like that and should be able to EQ the system with the right simple 2 order filter. See post 17 here: http://www.diyaudio.com/forums/subwoofers/166243-please-recommend-10-subwoofer-2.html
Also note, if one uses a horn for bass there is a lot of time for the bass to travel down the throat of that beautiful horn like "hm" post. This means the 'system' needs to somehow be moved forward in time. This can be done by bringing the woofer closer to the listening position by the length of the throat than the midrange or midbass transducer.
As a thought for the thread starter, try moving your subwoofers closer to your listening position by several feet and see if that helps your situation.
As frequency increases radiation resistance also increase as the square of the frequency which is why a 1 inch tweeter will play as loud in its passband as an 18 inch woofer in its passband. From a mechanical analysis standpoint of first approximation all direct radiator transducers for audio are second order low pass systems which show linear motion response below resonance and roll off at -12dB per octave above resonance. This roll off effect above resonance is the region we use drivers because that matches up with the radiation resistance to give a flat acoustic response, more of less, in the acoustic passband. What does this mean? In reference to driver size and frequency the acceleration and acoustic load of the driver increases with higher frequency. A larger driver moves less distance to make the same SPL and therefore experiences lower acceleration for the same SPL. Fast is not maximum speed, FAST is acceleration. As on "hm" web page the conclusion that a more powerful motor (all other things being equal) will always be faster is true. This is why I like the biggest magnet there are with the higher resistance voice coil because that leads to the most powerful motor. Then there is the part about the heavy cone on "hm" web page. While it is clear given the same force a heavier cone will accelerate more slowly is absolutely true however, if that light cone bends and flops around it just does not matter. The cone needs to behave as a unit and move as one piece and not flop like a fish out of water. To achieve that a very rigid and well damped cone is needed. This then means a big magnet and powerful motor is also needed. Floppy and sloppy are easy and cheap. Solid and powerful are not cheap in drivers or in amplifiers usually.
The drivers the starter of this thread is using are very good IMO. He just needs to EQ the drivers for flat response and his "slow polite" bass will turn into to gut punching bass.
Resonance peaked bass response as is so very common and the heart of ports is a big step in the wrong direction because resonance peaking means to store energy. Storing energy is good for making sine waves but is not worth a darn for transient response. No one ever talks about the FACT that the radiation from a port is one full cycle behind the active driver. Lousy for transients but good for making continuous sine waves. Best impulse response is clearly with a Q in box of 0.577 Bessel response as often defined in filter theory. The thread starter has a system very much like that and should be able to EQ the system with the right simple 2 order filter. See post 17 here: http://www.diyaudio.com/forums/subwoofers/166243-please-recommend-10-subwoofer-2.html
Also note, if one uses a horn for bass there is a lot of time for the bass to travel down the throat of that beautiful horn like "hm" post. This means the 'system' needs to somehow be moved forward in time. This can be done by bringing the woofer closer to the listening position by the length of the throat than the midrange or midbass transducer.
As a thought for the thread starter, try moving your subwoofers closer to your listening position by several feet and see if that helps your situation.
hm, do you make this "theory" up while you post? with modern amplifiers, you can safely say that they dont matter. they all sound the same, of course within pragmatical dimensions. i wont say you cant measure differences, but that doesnt mean you can hear them. also, a membrane cant slow music down! music can only be slowed if you change the speed of the turntable. read some basic physics books and then rethink your ideas.
and this link... i dont know what to say. its just... borderline humor? totally wrong? well... luckily its in german and most guys wont understand it.
and this link... i dont know what to say. its just... borderline humor? totally wrong? well... luckily its in german and most guys wont understand it.
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Hello,
"Also note, if one uses a horn for bass there is a lot of time for the bass to travel down the throat of that beautiful horn like "hm" post. This means the 'system' needs to somehow be moved forward in time. This can be done by bringing the woofer closer to the listening position by the length of the throat than the midrange or midbass transducer."
No,
40 Hz 4 waves to get by our ear-brain system,
than the tone makes 32 m distance nearly 100 msec,
how large is your room?
you can´t listen a delay of 10 msec,
look the Präzedenseffect
Präzedenz-Effekt ? Wikipedia
MAVO,
arm, das du nicht mal die neuen Untersuchungen dazu kennst,
Stereoplay die letzten Monate.
Only:
- over 90% of the resulting reproduced sound from a good recording, depends on:
the room, the drivers, the building elements used for the cabinet
and the cabinet design. The remaining percentages may be obtained through careful
choices of electronics for signal processing, cabels and equipment dampers etc.
--------------------------
"a pair of Lowther Acoustas with DX4" is the problem,
i never heard a sealed or BR or OB that will get the dynamic
of the DX4
"Also note, if one uses a horn for bass there is a lot of time for the bass to travel down the throat of that beautiful horn like "hm" post. This means the 'system' needs to somehow be moved forward in time. This can be done by bringing the woofer closer to the listening position by the length of the throat than the midrange or midbass transducer."
No,
40 Hz 4 waves to get by our ear-brain system,
than the tone makes 32 m distance nearly 100 msec,
how large is your room?
you can´t listen a delay of 10 msec,
look the Präzedenseffect
Präzedenz-Effekt ? Wikipedia
MAVO,
arm, das du nicht mal die neuen Untersuchungen dazu kennst,
Stereoplay die letzten Monate.
Only:
- over 90% of the resulting reproduced sound from a good recording, depends on:
the room, the drivers, the building elements used for the cabinet
and the cabinet design. The remaining percentages may be obtained through careful
choices of electronics for signal processing, cabels and equipment dampers etc.
--------------------------
"a pair of Lowther Acoustas with DX4" is the problem,
i never heard a sealed or BR or OB that will get the dynamic
of the DX4
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