I am looking for woofer which has good bass impact in 6.5" and 8".
For picking out that kind of woofer, what factors of the driver should I check ?
Fs, Mms, Cms, Bl, Qms, Qts, VAS, sensitivity, impedance peak at Fs, cone material (PP, Paper, Metal..), voicecoil diamater, curvature of cone, shape of dust cap ??
(This is for question for Bass reflex type.)
For picking out that kind of woofer, what factors of the driver should I check ?
Fs, Mms, Cms, Bl, Qms, Qts, VAS, sensitivity, impedance peak at Fs, cone material (PP, Paper, Metal..), voicecoil diamater, curvature of cone, shape of dust cap ??
(This is for question for Bass reflex type.)
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Bass impact depends on first and foremost moving air.
However the character of the bass depends on a variety of factors that are somewhat difficult to combine into a recipe that can be followed simply.
The room, the amplifier and the driver and how it is applied will all play a role.
Generally speaking "impact" requires that a certain threshold level, some SPL be reached. Beyond that the Qt of the system, and the harmonics of the particular driver plays a role in how the bass is perceived.
Most 6.5" and 8" don't go all that low, so one's perceptions are going to be governed by things other than purely low Hz.
Imo, the parameters you mentioned probably will not be sufficient to determine how a given driver will sound in terms of "impact".
By way of an anecdotal story, one of the best small speakers for "impact" that I ever built or heard came about more or less as the result of a desperate situation where I was looking FOR bass out of a fixed volume enclosure. The drivers were (iirc) Peerless 8" bextrene cones with a bit too low of a Qt for the situation. I had hoped to use two of them in parallel. Sounded terrible, I was not happy. Going back to one was really rather uninspiring, better but not good.
The solution came in an isobaric configuration. Absolutely kicked tail. Rather surprised me as to how good it sounded, worked out to be a killer small cabinet.
I'm not saying that an isobaric is the solution to anything. But it shows how the same driver(s) used differently can certainly yield very different sonic outcomes.
_-_-
However the character of the bass depends on a variety of factors that are somewhat difficult to combine into a recipe that can be followed simply.
The room, the amplifier and the driver and how it is applied will all play a role.
Generally speaking "impact" requires that a certain threshold level, some SPL be reached. Beyond that the Qt of the system, and the harmonics of the particular driver plays a role in how the bass is perceived.
Most 6.5" and 8" don't go all that low, so one's perceptions are going to be governed by things other than purely low Hz.
Imo, the parameters you mentioned probably will not be sufficient to determine how a given driver will sound in terms of "impact".
By way of an anecdotal story, one of the best small speakers for "impact" that I ever built or heard came about more or less as the result of a desperate situation where I was looking FOR bass out of a fixed volume enclosure. The drivers were (iirc) Peerless 8" bextrene cones with a bit too low of a Qt for the situation. I had hoped to use two of them in parallel. Sounded terrible, I was not happy. Going back to one was really rather uninspiring, better but not good.
The solution came in an isobaric configuration. Absolutely kicked tail. Rather surprised me as to how good it sounded, worked out to be a killer small cabinet.
I'm not saying that an isobaric is the solution to anything. But it shows how the same driver(s) used differently can certainly yield very different sonic outcomes.
_-_-
The type of enclosure is common bass reflex one.
The impact means thick, dark and heavy attack in bass.
It is related with subwoofer type of bass.
In my experience, the woofers which has weak impact are Accuton, Seas Excel magnesium cone series, Seas CA22RNX, and Scanspeak discovery series,
and has good impack are Audiotechnology Flex series and Seas CD22RN4X.
Not sure how far you want to get into this subject, I am trying to give you some practically useful (and proven, by lots of experimenting) advice about bass impact and extension. Many years I've tried to get the holy grail of the "small box with good LF extension, impact, and low distortion"
After trying numerous drivers (mostly 5-6.5 inchers) in different size and type enclosures, here is what I found out. The triple criteria of small box with impact and extension and low distortion, is somewhat difficult to realize with the traditional methods ie. single woofer in a certain type of box- we all know that. However one kind of loading - the push-pull compound (or Isobaric) in a vented enclosure is a completely different story.
Let's see it step by step. First the good news. With a given driver you can practically use a box with half size (well, close to half, because of the sealed chambers extra volume beetween the drivers) of the single drivers volume.
Not many of us are aware of the fact, that the low frequency distortion of most woofers is drastically high. This is due to the flexing mode of the cone -not much can be done about it. In this area metal or honeycomb cone woofers are much better than paper or plastic cone ones.
However, in P-P compound mode if you mount your drivers back to back, this kind of distortion effectively cancels itself by moving the cones in opposing directions regarding their mounting positions. The resulting distortion level is a fraction of the single driver config.
Interestingly there is much more to this kind of setup, than theory suggests.
If you ever build (or listen somewhere) a pair, you will immediately notice that its bass is wwway better than you could have imagined... Goes deep, visceral in impact yet well articulated.
In a recent build I've used a pair of Hi-Vi D6.8 woofers (3" voice coil, cast frame, 11mm linear excursion) -super drivers for the price- coupled to a 1" alu. dome (I will upgrade that to something better), and all my friends came to listen asked immediately; OK, the bass is super, but where is the sub hidden?
In my living room (cca. 300 sq.feet) positioned 3 feet from rear, 5 feet from side walls on 50 pound sand filled stands, the listening position extension is 28 Hz (-3dB), which is not bad from a 2/3 cu.ft. pair of boxes.
Well the low side..... Since you must wire the woofers parallel (and of course out of phase because of the back-to back mounting), the impedance drops just below 3 ohms around 120Hz, and these things crave power, I mean it. Below 100 watts to 3-4 ohms you better not even try to drive them, you will loose all the energy these thing are able to produce with proper drive. Also efiiciency is..... khmmm. around 83-84 dB , so as you see it is not a project for everyone.
I am glad to give further details on the design if anyone interested. You have been warned.....
After trying numerous drivers (mostly 5-6.5 inchers) in different size and type enclosures, here is what I found out. The triple criteria of small box with impact and extension and low distortion, is somewhat difficult to realize with the traditional methods ie. single woofer in a certain type of box- we all know that. However one kind of loading - the push-pull compound (or Isobaric) in a vented enclosure is a completely different story.
Let's see it step by step. First the good news. With a given driver you can practically use a box with half size (well, close to half, because of the sealed chambers extra volume beetween the drivers) of the single drivers volume.
Not many of us are aware of the fact, that the low frequency distortion of most woofers is drastically high. This is due to the flexing mode of the cone -not much can be done about it. In this area metal or honeycomb cone woofers are much better than paper or plastic cone ones.
However, in P-P compound mode if you mount your drivers back to back, this kind of distortion effectively cancels itself by moving the cones in opposing directions regarding their mounting positions. The resulting distortion level is a fraction of the single driver config.
Interestingly there is much more to this kind of setup, than theory suggests.
If you ever build (or listen somewhere) a pair, you will immediately notice that its bass is wwway better than you could have imagined... Goes deep, visceral in impact yet well articulated.
In a recent build I've used a pair of Hi-Vi D6.8 woofers (3" voice coil, cast frame, 11mm linear excursion) -super drivers for the price- coupled to a 1" alu. dome (I will upgrade that to something better), and all my friends came to listen asked immediately; OK, the bass is super, but where is the sub hidden?
In my living room (cca. 300 sq.feet) positioned 3 feet from rear, 5 feet from side walls on 50 pound sand filled stands, the listening position extension is 28 Hz (-3dB), which is not bad from a 2/3 cu.ft. pair of boxes.
Well the low side..... Since you must wire the woofers parallel (and of course out of phase because of the back-to back mounting), the impedance drops just below 3 ohms around 120Hz, and these things crave power, I mean it. Below 100 watts to 3-4 ohms you better not even try to drive them, you will loose all the energy these thing are able to produce with proper drive. Also efiiciency is..... khmmm. around 83-84 dB , so as you see it is not a project for everyone.
I am glad to give further details on the design if anyone interested. You have been warned.....
Here are a few shots of the box, I will dig out the box plans some day. They are veneered with "whiteish" sycamore-maple (if I am correct), over 3/4" and 1" MDF. The back plates are removable (obviously, inner driver access) fastened with 1/6" metal bolts into threaded sleeves. Their net internal volume is cca. 15 liters, plus the PPC enclosure, so overall about 19 liters. Tuning is done with 1.8" i.d. PVC tube 21cm (8.3")long both ends flared. I am not going into details with the crossover, it is still in the works, but I must find a tweeter witl low Fs, no ferrofluid and very good sound without costing a lot. My primary candidate (based on previous experiments ) is the SB29 RDC from SB Acoustics. The planned Xo freq. is around 2.2kHz, looking up with some sim. programs it can be done with a simple 2nd order voiced in for the particular drivers.
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Not sure how far you want to get into this subject, I am trying to give you some practically useful (and proven, by lots of experimenting) advice about bass impact and extension. Many years I've tried to get the holy grail of the "small box with good LF extension, impact, and low distortion"
After trying numerous drivers (mostly 5-6.5 inchers) in different size and type enclosures, here is what I found out. The triple criteria of small box with impact and extension and low distortion, is somewhat difficult to realize with the traditional methods ie. single woofer in a certain type of box- we all know that. However one kind of loading - the push-pull compound (or Isobaric) in a vented enclosure is a completely different story.
Let's see it step by step. First the good news. With a given driver you can practically use a box with half size (well, close to half, because of the sealed chambers extra volume beetween the drivers) of the single drivers volume.
Not many of us are aware of the fact, that the low frequency distortion of most woofers is drastically high. This is due to the flexing mode of the cone -not much can be done about it. In this area metal or honeycomb cone woofers are much better than paper or plastic cone ones.
However, in P-P compound mode if you mount your drivers back to back, this kind of distortion effectively cancels itself by moving the cones in opposing directions regarding their mounting positions. The resulting distortion level is a fraction of the single driver config.
Interestingly there is much more to this kind of setup, than theory suggests.
If you ever build (or listen somewhere) a pair, you will immediately notice that its bass is wwway better than you could have imagined... Goes deep, visceral in impact yet well articulated.
In a recent build I've used a pair of Hi-Vi D6.8 woofers (3" voice coil, cast frame, 11mm linear excursion) -super drivers for the price- coupled to a 1" alu. dome (I will upgrade that to something better), and all my friends came to listen asked immediately; OK, the bass is super, but where is the sub hidden?
In my living room (cca. 300 sq.feet) positioned 3 feet from rear, 5 feet from side walls on 50 pound sand filled stands, the listening position extension is 28 Hz (-3dB), which is not bad from a 2/3 cu.ft. pair of boxes.
Well the low side..... Since you must wire the woofers parallel (and of course out of phase because of the back-to back mounting), the impedance drops just below 3 ohms around 120Hz, and these things crave power, I mean it. Below 100 watts to 3-4 ohms you better not even try to drive them, you will loose all the energy these thing are able to produce with proper drive. Also efiiciency is..... khmmm. around 83-84 dB , so as you see it is not a project for everyone.
I am glad to give further details on the design if anyone interested. You have been warned.....
Thank you very much for sharing your esteemed experience.
I'll try isobaric for my next DIY.
Then, I would like to have your opinion for the design.
A. In case of 2 ways
A-1. Two 6.5" low Q woofers (such as SS 18W/8545 or Eton 7-200) the cabinet volume around 10 liters
A-2. Two 6.5" high Q woofers (such as SS 18W/8531G or Seas CA18RLY) the cabinet volume around 16~20 liters
B. In case of 3 ways
B-1. Two 6.5" high Q woofers the cabinet volume around 16~20 liters
B-2. Two 8" woofers (such as Eton 8-200 or SS 22W/8555) the cabinet volume around 25 liters
Among the aboves, which one would you like to recommend ?
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Oh yeah..... Don't ask about the tweeters, they are the "one pair on the planet" type, put together from different parts sourced from China . They are excellent, fast, super detailed, except their metallic overtone coming through on certain materials. I prefer well made soft domes, but really there are very few of them I like. And the ones I do, i cannot afford.....
. They are excellent, fast, super detailed, except their metallic overtone coming through on certain materials. I prefer well made soft domes, but really there are very few of them I like. And the ones I do, i cannot afford.....
After looking up some quick simulation, I would go for the 8531-s. In PPC configuration with a net volume of cca. 23 liters (+the compound enclosure of course) tuned to 30 Hz, you can get a -3dB point of 31 Hz, which is pretty good, about the same as with the Hi-Vi-s, in a slightly larger box....
If I were you, (which I am obviously not) I would forget about 3 way, it is really a pain believe me it is magnitudes more difficult to get them sound "right" than a properly executed two way
If I were you, (which I am obviously not) I would forget about 3 way, it is really a pain believe me it is magnitudes more difficult to get them sound "right" than a properly executed two way
Thank you for your suggestion.
According to my calculation by Bassbox Pro, the appropriate volume of cabinet of 8531G (Ots 0.36, VAS 58.2 liters based on manufacturer spec) is 31.2 liters with single and 16.1 liters with isobaric.
It is quite different from your simulation (23 liters vs. 16.1 liters).
Can I know your calculation method ?
I converted a vented enclosure to isobaric by bolting a second identical driver over the existing driver. This gave the front to front effect you have described.
It taught me that the way too small Tannoy Berkley plays bass much better by isobarically converting it to an Arden.
So I built an arden clone and since I have two bass speakers I have can have two arden clones.
Now I can get bass that is 6dB louder or send signals that are 1/4 power and reduce distortion at the same SPL as I need.
The two arden clones play far better, than the two drivers in isobaric mode.
This I did about 15years to 20years ago and the theory behind it has not changed !
It taught me that the way too small Tannoy Berkley plays bass much better by isobarically converting it to an Arden.
So I built an arden clone and since I have two bass speakers I have can have two arden clones.
Now I can get bass that is 6dB louder or send signals that are 1/4 power and reduce distortion at the same SPL as I need.
The two arden clones play far better, than the two drivers in isobaric mode.
This I did about 15years to 20years ago and the theory behind it has not changed !
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Actually there is not only one way to heaven (or hell if you like), it depends on your chosen- and personally preferred tuning method. It can be BB4, SBB4, SC4, QM3, just to mention a few... Where they differ from each other is mostly their monotonicity (upper bass overshot, transfer band ripple magnitude etc.), So my method might differ from others, but personally I think (based on 35 years of experience) this gives the best result - the way I like it- minimum ripple, no overshot, max. LF extension. Actually my fave is the QM3, but not many know about it......
Isobaric will cut the needed volume in half (reducing with, hight, depth by 20%) if the box is much smaller than Vas and that the total volume of the second driver and coupling chamber is much smaller than the total internal volume. So for a 18" driver that needs large space it might be a good idea but for a 6.5" (sub)woofer?
The type of enclosure is common bass reflex one.
The impact means thick, dark and heavy attack in bass.
It is related with subwoofer type of bass.
/QUOTE]
Can be true....but it's also the Signature of an ineptly designed enclosure
No shortage of those.. are there?
IMO Bass starts with min of 8"' drivers, all else is smoke 'n mirrors.
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