I'm going to be making 3-way floor-standing and also 2-way stand-mounted speakers, for use with music (not usually movies). To help sanity-check my goals for these I've been looking at the specs (and where possible measurements) of commercial examples by popular hi-fi brands such as Warfedale etc. Most don't go as low in frequency as I'd expected and also roll off much more steeply - often only several Hz between -3dB and -6dB. For example, many (most?) floorstanders I looked at have -3dB and -6dB in the region of 45hz and 40hz respectively, whilst bookshelf types are of course somewhat higher - maybe 55hz and 50hz, or even 65hz and 60hz in some cases - yet still get good reviews.
I had been planning to shoot for somewhat lower (say 35hz) and certainly 'much' shallower roll-offs with a Q of around 0.7 (though it is going to be an active system so could be DSP'd to almost anything, within reason). But that would be at the significant expense of some SPL, and almost certainly more complication from room resonances and annoyance of neighbors etc. So, going by the above commercial examples, this may possibly not be a worthwhile trade-off to make.
So, ideals aside, I was wondering what people on here would classify as a sensible/acceptable/reasonable/normal target for roll-off rate and frequency - for DIY 2-ways and 3-ways?
Thanks,
Kev
I had been planning to shoot for somewhat lower (say 35hz) and certainly 'much' shallower roll-offs with a Q of around 0.7 (though it is going to be an active system so could be DSP'd to almost anything, within reason). But that would be at the significant expense of some SPL, and almost certainly more complication from room resonances and annoyance of neighbors etc. So, going by the above commercial examples, this may possibly not be a worthwhile trade-off to make.
So, ideals aside, I was wondering what people on here would classify as a sensible/acceptable/reasonable/normal target for roll-off rate and frequency - for DIY 2-ways and 3-ways?
Thanks,
Kev
A list of 273 commercial loudspeaker measurements can be found here: https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=16&Itemid=140
The trade-off between cut-off frequency and maximum output strongly depends on taste and size of the listening room. Luckily, it is easy to change, by changing the port tuning and DSP settings.
I would add a 2nd order high pass to both closed and vented loudspeakers, resulting in 4th and 6th order high pass characteristics respectively. This offers a reasonable amount of subsonic protection. I do not think that the box alignment and electrical high pass filter characteristics (other than cut-off frequency) are that important for sound quality, because their effects will be swamped by room acoustics anyway. Then the whole package of filter, loudspeaker and room, should be equalized to some target curve.
One thing to keep in mind is that equalizing a closed box woofer to a low Q, is very expensive in terms of maximum output. The same woofer in a ported box can play about 10 dB louder.
The trade-off between cut-off frequency and maximum output strongly depends on taste and size of the listening room. Luckily, it is easy to change, by changing the port tuning and DSP settings.
I would add a 2nd order high pass to both closed and vented loudspeakers, resulting in 4th and 6th order high pass characteristics respectively. This offers a reasonable amount of subsonic protection. I do not think that the box alignment and electrical high pass filter characteristics (other than cut-off frequency) are that important for sound quality, because their effects will be swamped by room acoustics anyway. Then the whole package of filter, loudspeaker and room, should be equalized to some target curve.
One thing to keep in mind is that equalizing a closed box woofer to a low Q, is very expensive in terms of maximum output. The same woofer in a ported box can play about 10 dB louder.
As you have DSP, you can use that to reduce room resonances and annoyance to the neighbours.
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I've found bookshelf speakers rather gutless in the bass and never bought any. When I could only afford bookshelves, I used 6x9" car speakers in a vented cardboard box while I saved up for LWEIII. The cheapest speakers I ever purchased & listened to for years had 10" woofers in a sealed box 2.5 cu ft. I find speakers -3 db at 54 hz & -10 db at 40 to be adequate. I don't run a sub. I do listen to piano and pipe organ that have 26 hz & 32 hz notes. I've always backed the speakers 6" from a hard wall on the long dimension of the room. I found recently by measuring this provides about 3 db of room gain in the bass.
In the TV room where fidelity is less important to me, I've run 6.5" whizzer cone speakers in a 14" long vented cardboard box. Salvage from projection screen TV's. Probably 100 hz or higher. HDTV can go down in frequency, but I rarely see lowest octave piano solos on TV. Dynamic range is heavily reduced on TV IMHO. I do enjoy 55 db peaks in the music room sometimes.
I found the subsonic rolloff in my RA-88a mixer annoying and always ran it turned off. It was first order filter, a simple cap series the op amp input. There wasn't any sub filter on the predecessor dynaco PAS2 preamp, although the transformer in the ST70 tube amp probably stopped subsonics. This means after converting to SS amp (dynaco ST120) my woofers bounced 3/4" when I walked across the floor with the phono needle on the record. I haven't damaged them.
In the TV room where fidelity is less important to me, I've run 6.5" whizzer cone speakers in a 14" long vented cardboard box. Salvage from projection screen TV's. Probably 100 hz or higher. HDTV can go down in frequency, but I rarely see lowest octave piano solos on TV. Dynamic range is heavily reduced on TV IMHO. I do enjoy 55 db peaks in the music room sometimes.
I found the subsonic rolloff in my RA-88a mixer annoying and always ran it turned off. It was first order filter, a simple cap series the op amp input. There wasn't any sub filter on the predecessor dynaco PAS2 preamp, although the transformer in the ST70 tube amp probably stopped subsonics. This means after converting to SS amp (dynaco ST120) my woofers bounced 3/4" when I walked across the floor with the phono needle on the record. I haven't damaged them.
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A box with a hole in it will roll off forth order, a sealed box 2nd order.
F3 is a more or less meanless to humans (Toole). Look at the F6/F10.
In an ideal world, with room gains, you want this in the neighborhood of 40 Hz so that the lowest (more typical) notes can be reproduced. The room canmake a big difference.
Most commerial loudspeakers don’t go as low as you might think,
If you follow Toole & Geddes, you should aim for F3 of about 80 Hz and XO to multiple separate woofers.
dave
F3 is a more or less meanless to humans (Toole). Look at the F6/F10.
In an ideal world, with room gains, you want this in the neighborhood of 40 Hz so that the lowest (more typical) notes can be reproduced. The room canmake a big difference.
Most commerial loudspeakers don’t go as low as you might think,
If you follow Toole & Geddes, you should aim for F3 of about 80 Hz and XO to multiple separate woofers.
dave
The only correct answer is: how large is your room and how are the loudspeakers located with respect to its walls?
Well said Dave! And I can corroborate this from personal experience. My speakers are small, (13L) sealed and have a an F3 of 54 Hz. When the bass is in the music you can hear it quite well but there is no false loose or flabby bass ever. Tight, accurate and pretty full for their size. Would a sub that can play the next lowest octave be nice? Probably. And so I built two wih F3's of 35 Hz to act as stands. And they make great speaker stands but have not yet felt a need to actually hook them up and use them these speakers!
I have 2 sets of speakers that I generally run with. B&W DM14 and from on this site XRK Reference Monitors.
The former a 28litre sealed 2.5way with 2 x (big for a 6.5) 6.5"s
XRKS are 17litre (below the design spec of 24litre) sealed with 8". The XRK have full 6db baffle step.
Always my speakers are close to the wall and not miles away from side walls....plenty boundary reinforcement of LF.
B&W definitely less LF but I think maybe it is a better quality bass in my room and ears. I find the XRK dig very deep in my room but they excite and load it up. Sounds impressive but the LF pressures get to my ears after a time.
So the room and placement have a big effect as mentioned. And also the BSC.
The former a 28litre sealed 2.5way with 2 x (big for a 6.5) 6.5"s
XRKS are 17litre (below the design spec of 24litre) sealed with 8". The XRK have full 6db baffle step.
Always my speakers are close to the wall and not miles away from side walls....plenty boundary reinforcement of LF.
B&W definitely less LF but I think maybe it is a better quality bass in my room and ears. I find the XRK dig very deep in my room but they excite and load it up. Sounds impressive but the LF pressures get to my ears after a time.
So the room and placement have a big effect as mentioned. And also the BSC.
Actually, you need some sort of electronic control over your bass level because it is sheer coincidence if the loudspeaker characteristics and those of the room are a good match.
Thanks everyone for all the thoughts and info! They don't seem to disagree with what I was finding in commercial speakers, or at least the better examples. That is good news; I can aim for a bit higher then (and so also somewhat louder) than i'd originally imagined for the low end, which makes life easier.
Accommodation is not very consistent at the moment (whereas I'm hoping the speakers will be); so designing for a particular room/room-size is not a luxury that I have. Instead, the intention is to get the hardware working sensibly in its own right and then use DSP to fine -tune things as circumstances change.
Accommodation is not very consistent at the moment (whereas I'm hoping the speakers will be); so designing for a particular room/room-size is not a luxury that I have. Instead, the intention is to get the hardware working sensibly in its own right and then use DSP to fine -tune things as circumstances change.
the lower your cutoff the louder your speaker needs to be to benefit from it.
making a 4" speaker go to 20 hz would be a complete waste as you wouldn't hear it any lower than about 50 hz anyway.
on other hand it would also be a waste to NOT make a dual 21" subwoofer go to 20 hz.
frequency and SPL must be looked at together with an eye on fletcher munson equal loudness curves.
making a 4" speaker go to 20 hz would be a complete waste as you wouldn't hear it any lower than about 50 hz anyway.
on other hand it would also be a waste to NOT make a dual 21" subwoofer go to 20 hz.
frequency and SPL must be looked at together with an eye on fletcher munson equal loudness curves.
Thank you, that is an interesting insight into something I wondered about previously when building and testing my speakers... Modelling applications like WinISD will give convincing curves based upon driver excursion and frequency response, but they didn't seem to tell the whole story; a bigger driver in an enclosure supposedly arriving at the same SPL/frequency curve (as a smaller one) had noticeably more 'umph' when playing music in reality (i.e. even at the same SPL).
It is as if there is more to it than the volume (driver area x excursion) of air moved, which i assume the modelling software uses to predict output. Not sure how to quantify that, except to curb my low-frequency expectations for the small 2-ways even if the simulated curves look okay. Perhaps that would also be worthwhile in terms of distortion of smaller drivers moving further (even within linear excursion?) which the software also doesn't show.
Though another approach may be using different DSP/filters to have two different low-frequency curves: a lower option just for near/low-volume listening and a higher one for normal/louder SPLs.
Cheers,
Kev
^I guess that modelling software doesn't count for acoustic efficiency difference - small Sd with high excursion looses to high Sd and low excursion at same (high) spl. As well a bass reflex port will have very small area (Sd) and add resonaces, air-flow noise and excess group delay.
An interesting test of subwoofers here
https://data-bass.com/#/articles/5cb774640ca6e70004e10828?_k=l4nzrg
An interesting test of subwoofers here
https://data-bass.com/#/articles/5cb774640ca6e70004e10828?_k=l4nzrg
well there is no such thing as linear excursion
all excursion is non-linear
so if you look at displacement as product of area and excursion really the area carries more weight than excursion does because area remains linear in bass while excursion does not
on other hand in higher frequencies it's the opposite - actually area begins to shrink as cone goes into breakup
all programs assume excursion is linear because you need some kind of expensive klippel measurements to actually measure the nonlinearity of excursion and even then there is no standardized way to express what you measure other than a curve / chart that software can't use and XMAX which is a gross simplification
when it comes to bass you should always look at area first and displacement second ... the reason people often go the opposite route is because more cone area means bigger box while excursion is free in terms of box size ...
but nothing is ever really free ...
all excursion is non-linear
so if you look at displacement as product of area and excursion really the area carries more weight than excursion does because area remains linear in bass while excursion does not
on other hand in higher frequencies it's the opposite - actually area begins to shrink as cone goes into breakup
all programs assume excursion is linear because you need some kind of expensive klippel measurements to actually measure the nonlinearity of excursion and even then there is no standardized way to express what you measure other than a curve / chart that software can't use and XMAX which is a gross simplification
when it comes to bass you should always look at area first and displacement second ... the reason people often go the opposite route is because more cone area means bigger box while excursion is free in terms of box size ...
but nothing is ever really free ...
Subwoofer in what application? In pro audio where most modern 21" drivers are designed for use, it IS a waste. Below 40Hz is not needed much of the time and 20Hz requires 4x the Vd of 40Hz.
PA is not a unified group, regarding bass (the topic here) a small jazz club must have different application than open air festival for 30.000 people!
My favourite local club uses a single 24" sealed sub. Oh boy, upright bass and kick drum sounds so good!
My favourite local club uses a single 24" sealed sub. Oh boy, upright bass and kick drum sounds so good!
I've actually run my PAs in both clubs and outdoor, though not 30k. Doesn't change the physics.
DB is seldom tuned below E1 or 41Hz so you're making my point for me. I'm a bassist so I have a really good idea what it takes to reproduce it.
Actually read some of the threads over the years. I've been posting here 20, not since last week.
Interesting stuff on the linearity and acoustic efficiency, that info was new to me so thanks both of you for that.
I shall make more effort to use the 3-way in more situations then. The bass woofer also has far less compromise needed on SPL and FR of course, so it makes sense in a number of ways.
However for the 2-ways I've been doing some modelling for a small range of possibilities, with the following FR vs SPL characteristics as Xmax is reached:
I think this represents the range from lower frequency than needed (which might be usable for quiet/near listening) through to the least-low that I can bring myself to intentionally target (for more SPL). But as this will be an actively filtered system I'll probably set up a couple/few switchable options in that range, depending on how I want to listen to the music at the time.
Cheers,
Kev
I shall make more effort to use the 3-way in more situations then. The bass woofer also has far less compromise needed on SPL and FR of course, so it makes sense in a number of ways.
However for the 2-ways I've been doing some modelling for a small range of possibilities, with the following FR vs SPL characteristics as Xmax is reached:
I think this represents the range from lower frequency than needed (which might be usable for quiet/near listening) through to the least-low that I can bring myself to intentionally target (for more SPL). But as this will be an actively filtered system I'll probably set up a couple/few switchable options in that range, depending on how I want to listen to the music at the time.
Cheers,
Kev