AndrewT said:
Hi Andrew,
Sorry, your email to me went to the spam folder. I just found it.
Yes, we are being a bit loose with the terminology here, but I thought it was quite clear. Sensitivity (efficiency) of the speaker, not the driver. It is a speaker system we are talking about, right?
Obviously, you can't change the efficiency (sensitivity) of a single driver by adding more.
Ok do I understand this right, reading the "Books" add a driver in parallel plus 3dB, add a driver in series lose 3dB, 4 drivers series/parallel net gain in efficiency zero BUT reduces excursion increases powerhandling, reduces group delay?? ( sounds better) and reduces power compression??
Would it not be better then to always use multiple drivers if it's within budget??
I think I asked earlier what was better sounding 1 really big driver or multiple smaller ones, thinking about this I am tempted to go with 4 X 10 inch rather than 1 X 15 as combined radiating area of the 4 X 10 inch drivers is greater.
Lets assume for the sake of this exercise that my mids are going to be the Vifa M11 MH-08 which I have, these are rewound to 16RNom, DCR 11.6ohms, if they were 88dB before they are now 85db/1W/1M, parallel 2 for MTM we get back to 88dB/W/M, they are rated at 40 watts nominal each and 110 watts each peak.
If I cross them at a reasonable low point 250/300 and have about 150 clean watts avaliable how do I work out how loud they might be?? If I then use 10 inch drivers of this relatively low efficiency are 4 enough??
Would it not be better then to always use multiple drivers if it's within budget??
I think I asked earlier what was better sounding 1 really big driver or multiple smaller ones, thinking about this I am tempted to go with 4 X 10 inch rather than 1 X 15 as combined radiating area of the 4 X 10 inch drivers is greater.
Lets assume for the sake of this exercise that my mids are going to be the Vifa M11 MH-08 which I have, these are rewound to 16RNom, DCR 11.6ohms, if they were 88dB before they are now 85db/1W/1M, parallel 2 for MTM we get back to 88dB/W/M, they are rated at 40 watts nominal each and 110 watts each peak.
If I cross them at a reasonable low point 250/300 and have about 150 clean watts avaliable how do I work out how loud they might be?? If I then use 10 inch drivers of this relatively low efficiency are 4 enough??
Moondog55 said:
15" contra 4x10" ... well, they are usually different kind of beasts with different specs
AEs TD15S seems to be a nice hifi driver fore closed box, not many of those around
10" seems to be a choise between Seas or SB
I would say that fore this kind of design you need a 90db midrange
AndrewT said:
At the upper end the width, across the driver effective piston area, determines when the gain starts to drop below the +3dB level (for dual drivers).graaf said:
If a pair of 18inch drivers are located 100mm (~4inches) apart then the piston areas extends to about 930mm.
The limiting frequency is about 90Hz. F=340/width/4, for speed of sound in m/S, width/length of radiating area in m, quarter wavelength.
Yes, that is correct, and if you have a perfect current source amp, I guess that is what you would get.
The juicy part of the explanation is that if you had two eight ohm drivers in parallel, you now have 4 ohms net. Your 4 ohms net now draws twice as many watts from your voltage source amp (and most are), so you end up with +3dB for increase in efficiency, and +3dB for the added power consumption. You get +6 dB net increase with two drivers in parallel as compared to a single driver of the exact same model.
With two drivers in series, you still get +3db for efficiency gain, but you lose 3dB if you are using a voltage source amp, since you now have twice the impedence resulting in half the current draw. Your net change is 0 dB.
Four drivers gives you +6dB over one driver, with the same impedence.
Yes, you will need 4x the box size to keep your Fcb from climbing through the roof.
JJ
This is the solution that I am working on at the present for a higher efficiency design. The plan is for a series/parallel network similar to the Elsinore's.
Most of the drivers I already had and since this is primarily for A/V mains I wanted more headroom and dynamics over absolute resolution. THe cabinet is 40 inches tall and the bottom footprint 16x22 inches.
The offset tweeter was a design necessity to keep the height at 40 inches. The lower woofers are about 3db more sensitive than the uppers so my plan still remains to be settled as a 3 way or a 2.5 way. Either way the lower crossover point will be at the approximate BSC frequency.
Driver's
5.5 Silverflute mid/bass
6.5 Silverflute mid/bass
Vifa 1 inch D27 linen dome tweeter
Vifa P21W 8.5 inch woofer
Aurum Cantus 10 inch poly/carbon/mica woofer
You cannot tell from this picture but the lower cabinet front baffle is slightly angled toward the listening position. The upper cabinet front baffle is vertical and the tweeter is about at ear height when I sit on the couch watching a movie.
Most of the drivers I already had and since this is primarily for A/V mains I wanted more headroom and dynamics over absolute resolution. THe cabinet is 40 inches tall and the bottom footprint 16x22 inches.
The offset tweeter was a design necessity to keep the height at 40 inches. The lower woofers are about 3db more sensitive than the uppers so my plan still remains to be settled as a 3 way or a 2.5 way. Either way the lower crossover point will be at the approximate BSC frequency.
Driver's
5.5 Silverflute mid/bass
6.5 Silverflute mid/bass
Vifa 1 inch D27 linen dome tweeter
Vifa P21W 8.5 inch woofer
Aurum Cantus 10 inch poly/carbon/mica woofer
You cannot tell from this picture but the lower cabinet front baffle is slightly angled toward the listening position. The upper cabinet front baffle is vertical and the tweeter is about at ear height when I sit on the couch watching a movie.
Attachments
"At the upper end the width, across the driver effective piston area, determines when the gain starts to drop below the +3dB level (for dual drivers)."
OK I am confused. I always thought that you got 3db for a second source and an additional 3 db if the 2 sources were in phase and less than 1/3-1/4 wavelength apart. So with closely spaced subs would get you an additional 6db gain between the second driver and the mutual coupling. Figure the additional 3 db from coupling would be driver spacing dependent
Rob
OK I am confused. I always thought that you got 3db for a second source and an additional 3 db if the 2 sources were in phase and less than 1/3-1/4 wavelength apart. So with closely spaced subs would get you an additional 6db gain between the second driver and the mutual coupling. Figure the additional 3 db from coupling would be driver spacing dependent
Rob
hmmm, how much bass is enough?
I've been listening to my OB bass for quite a while, which is big, consists of 3 x 18" per side ( it became 2 later ). It can provide lots of bass, more than enough for a normal living room. (especially mine is quite small)
With "only" 2 x 18" per side now, the sense of "bass power" is still more than enough, and good thing is the sound quality improves. It's more solid and controlled than when it was 3 per side.
It can play almost every kind of music with very good SPL, extension, and quality. The acoustical musical instruments are the best. I like drums, acoustic bass (double bass with bow), piano... etc from these OB.
On the other hand, in my other project recently, I got so impressed by the big bass horn, which is a pair of front loaded horn with 30Hz hypo flare and 18" driver. The energy it delivers is in quite another league. The sense of sub bass is phenomenal, and actually physical.
The bass from horn is so condensed yet so effortless. The extension is abyss and the energy is ground shaking.
I guess it's because the air loadings on the drivers are quite different. And the ways they load the room are also very different.
The OB bass is often like breeze, light and natural. So it sounds "correct" in most music and can deliver very high satifactions in a "musical way". I happened to listen a Gary Karr's album the other day. The OB sings beautifully. The friction textures between the bow and strings, and the rich resonaces of the big body were blended so beautifully. I was so content at that moment.
However when I switched to a pipe organ record, things changed. The senses of pressure and depth are weak. The 'picture' is big alright, but lack of the strong sense of depth and weight.
Adding several ticks on the EQ does little to the sub-30Hz region. Low 30 some Hz is probably the best OB bass can do, I'm afraid. (I'm not sure how low Magnetar's 21"er can do, though)
Below that 'pressure' region, big bass horn rules! Extending all the way down towards the abyss with immense dynamic range give me a feeling that both of its extension and SPL capabilities are way beyond me. That's so scary yet so exciting. I don't know where it can bring me.
But I also got a feeling that sometimes horns do a little 'over', I mean, more real than real. They kind of tend to yelling "look at me, I'm good". And, powerful it is, but overall I feel it not so coherent as OB. Maybe, it's because I'm still unfamiliar with them and have not tuned them right.
Both OB and horn are, may I say, "quick", but in so differnt ways. One is like wind, the other is like a rock hammering the ground. So, even at the frequency range both are good at, say, 40~80Hz, and at same SPL, they still sound very different.
I'd say, I can live with OB with music for most of the time, but I surely admire the "WOW" factor of a proper horn.
Man! why can't I have both
I've been listening to my OB bass for quite a while, which is big, consists of 3 x 18" per side ( it became 2 later ). It can provide lots of bass, more than enough for a normal living room. (especially mine is quite small)
With "only" 2 x 18" per side now, the sense of "bass power" is still more than enough, and good thing is the sound quality improves. It's more solid and controlled than when it was 3 per side.
It can play almost every kind of music with very good SPL, extension, and quality. The acoustical musical instruments are the best. I like drums, acoustic bass (double bass with bow), piano... etc from these OB.
On the other hand, in my other project recently, I got so impressed by the big bass horn, which is a pair of front loaded horn with 30Hz hypo flare and 18" driver. The energy it delivers is in quite another league. The sense of sub bass is phenomenal, and actually physical.
The bass from horn is so condensed yet so effortless. The extension is abyss and the energy is ground shaking.
I guess it's because the air loadings on the drivers are quite different. And the ways they load the room are also very different.
The OB bass is often like breeze, light and natural. So it sounds "correct" in most music and can deliver very high satifactions in a "musical way". I happened to listen a Gary Karr's album the other day. The OB sings beautifully. The friction textures between the bow and strings, and the rich resonaces of the big body were blended so beautifully. I was so content at that moment.
However when I switched to a pipe organ record, things changed. The senses of pressure and depth are weak. The 'picture' is big alright, but lack of the strong sense of depth and weight.
Adding several ticks on the EQ does little to the sub-30Hz region. Low 30 some Hz is probably the best OB bass can do, I'm afraid. (I'm not sure how low Magnetar's 21"er can do, though)
Below that 'pressure' region, big bass horn rules! Extending all the way down towards the abyss with immense dynamic range give me a feeling that both of its extension and SPL capabilities are way beyond me. That's so scary yet so exciting. I don't know where it can bring me.
But I also got a feeling that sometimes horns do a little 'over', I mean, more real than real. They kind of tend to yelling "look at me, I'm good". And, powerful it is, but overall I feel it not so coherent as OB. Maybe, it's because I'm still unfamiliar with them and have not tuned them right.
Both OB and horn are, may I say, "quick", but in so differnt ways. One is like wind, the other is like a rock hammering the ground. So, even at the frequency range both are good at, say, 40~80Hz, and at same SPL, they still sound very different.
I'd say, I can live with OB with music for most of the time, but I surely admire the "WOW" factor of a proper horn.
Man! why can't I have both
Keep it coming;
thinking and dreaming,
multiple drivers in parallel to give a 2 Ohm load wiered in series with a larger driver for the baffle step, 3 X 10inch (8/3 = 2.6R wired in series with a nominal 4 R sub to give that nominal 6R impedance ) easy load for most amps lots of cone area and in this configuration a cheap car sub might work
thinking and dreaming,
multiple drivers in parallel to give a 2 Ohm load wiered in series with a larger driver for the baffle step, 3 X 10inch (8/3 = 2.6R wired in series with a nominal 4 R sub to give that nominal 6R impedance ) easy load for most amps lots of cone area and in this configuration a cheap car sub might work
tinitus said:Maybe this thread should be named "How much bass is too much bass"
Yeah, I busted my house up pretty good once I had a system capable of reproducing pipe organ symphonies at ~live levels, so as long as I live here, my house's stick built/floating floor construction limits usable sub gain BW.
GM
hey guys,
I am having party this saturday at my house, and borrowed those PA speakers I built for our music group, 2 18" for bass, 4 6" for mids, horn radians for tweeters....plus 2500w behringers, yupiiii....somethings gona blow, I am confident about the amp, it was working all night at full power and nothing happened, plus it has protection.....woofers went to heaven once, but that was on the street, in the house there will be no need for so much bass....so we will see, maybe the house will go.....those are made of cardboard anyway
I am having party this saturday at my house, and borrowed those PA speakers I built for our music group, 2 18" for bass, 4 6" for mids, horn radians for tweeters....plus 2500w behringers, yupiiii....somethings gona blow, I am confident about the amp, it was working all night at full power and nothing happened, plus it has protection.....woofers went to heaven once, but that was on the street, in the house there will be no need for so much bass....so we will see, maybe the house will go.....those are made of cardboard anyway
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