GM said:
Thank you GM,
You mentioned 3 sizes to me in total which I've listed below. When you're mention you prefer the bigger yielding a more relaxed live sound would you be referring to #3, or the original #1? ie. Could #3 yield a subtly more relaxed sound than the smallest #2 or to get that do you have to go all the way to the biggest, #1?
1.
2.
3.
-Jerry
Hi Scottmoose,
Below I have summarized all I know about the box you first suggested for the AN cast 12. It is a traditional BR stuffed to the point of being nearly aperiodic.
The frequency chart shows this box to provide a bit lower extension than GM's tapered TL.
Can you please tell me how else, in general, such damped vent traditional BR's might differ from a stuffed tapered TL?
And what characteristics would it share with a transmission line?
Thank you,
-Jerry
frequency chart
Below I have summarized all I know about the box you first suggested for the AN cast 12. It is a traditional BR stuffed to the point of being nearly aperiodic.
The frequency chart shows this box to provide a bit lower extension than GM's tapered TL.
Can you please tell me how else, in general, such damped vent traditional BR's might differ from a stuffed tapered TL?
Scottmoose said:
And what characteristics would it share with a transmission line?
Thank you,
-Jerry
Scottmoose said:
frequency chart
VanJerry said:
It begins as an underdamped BR box with a resistive vent employed (i.e. the vent is stuffed as stated) which lowers the Q at the tuning frequency.
Yes, because it's tuned slightly lower. As you're intending to use a sub, there won't be much in it between the two boxes in practice.
They share similar technical response traits & a reasonably flat impedance (which is the prime object of the classic non-resonant aperiodic TL). Just different (albeit related) ways of achieving a similar object.
VanJerry said:
You're welcome!
You asked about #3 Vs #2, so that's what I responded to. Even factoring in an XO that will limit all their BWs, the large one will still sound more 'full'/'relaxed' than the smaller ones due to its much greater acoustic efficiency. Whether or not it's enough to justify the cost in $$/space only the individual can decide.
GM
Nordic said:
Yeah! How about a big horn / TL for the rest of us that want the 12 but can't afford none a your fancy subs.
Kofi
My 16 ft^3 TL example not have enough LF gain BW or big enough? Then maybe the ~18 Hz tuned 80.66 ft^3 BIB will somewhat 'flesh out' your sense of proportion and need to 'shake the rafters'. 😉
GM
GM
GM said:
I propose a new DIYaudio greeting for BIB aficionados:
"My house is your cabinet."
-Jerry
GM said:
Thank you GM,
I thought the one other difference between the 2 smaller tapered TL's and Scott's is that I read tapering might be better at preventing errant internal sound from bouncing back out through the 12's rather large driver diaphragm.
While there is a resistive vent, Scott's is internally underdamped. But I could use a Matrix approach inside Scott's to offset this.
Am I close to being right?
And the transients would be about the same for either?
Jerry
You're welcome!
Well, it's true that ideally you don't want the driver to develop standing waves from any boundary, but we're dealing with well damped cabs here that aren't large enough to develop them at a low enough frequency (i.e. high enough amplitude), so it's a moot point.
Oh really?! Looks ~like a well damped prosound alignment to me. All he did was add enough stuffing density to make it semi-aperiodic (over-damped) to get a bit smoother response and lower F3 out of an acoustically small cab.
Either what? I mean I've built plenty of prosound alignment type cabs that Scott's mimics if you damp it like any other BR, but never stuffed them since in these apps acoustic efficiency is pretty much everything. If the various sims are accurate enough to allow direct comparison though, then the small TL is best with each larger size being less so for a given stuffing density since the impedance peak increases with increasing cab Vb, but if you increase stuffing density proportionately they will all be the same, so as I recommended awhile back, build the biggest cab you can 'afford' and then make it as 'tight'/'fast' as you can tell the difference via stuffing density.
Anyway, I'm down to repeating myself as you waltz around this one performance parameter that in the scheme of things is mostly moot unless you're planning to drive them with a high output impedance amp, in which case this would make the smaller cabs larger, so 'color' me done.
GM
Well, it's true that ideally you don't want the driver to develop standing waves from any boundary, but we're dealing with well damped cabs here that aren't large enough to develop them at a low enough frequency (i.e. high enough amplitude), so it's a moot point.
Oh really?! Looks ~like a well damped prosound alignment to me. All he did was add enough stuffing density to make it semi-aperiodic (over-damped) to get a bit smoother response and lower F3 out of an acoustically small cab.
Either what? I mean I've built plenty of prosound alignment type cabs that Scott's mimics if you damp it like any other BR, but never stuffed them since in these apps acoustic efficiency is pretty much everything. If the various sims are accurate enough to allow direct comparison though, then the small TL is best with each larger size being less so for a given stuffing density since the impedance peak increases with increasing cab Vb, but if you increase stuffing density proportionately they will all be the same, so as I recommended awhile back, build the biggest cab you can 'afford' and then make it as 'tight'/'fast' as you can tell the difference via stuffing density.
Anyway, I'm down to repeating myself as you waltz around this one performance parameter that in the scheme of things is mostly moot unless you're planning to drive them with a high output impedance amp, in which case this would make the smaller cabs larger, so 'color' me done.
GM
Right, although it's actually my fault here -the underdamping was in reference to the original box I'd had in mind, with a 6in diameter vent, similar to the existing CSA BR boxes. Pillock that I am, I completely forgot that I'd changed it, and the alignment, by shifting to a 3in vent diameter before posting, which ~follows a damped pro-audio alignment as you say. Must've been having a 'senior moment' a few decades early. As-is, the resistive vent & some of the internal damping / stuffing are optional depending on whether you want to completely flatten the first impedance peak & a theoretically inaudible amount of ripple.
Attachments
Hey Jerry,
I just downloaded an audio test cd last night and played it a few minutes ago. It goes from 16Hz to 20kHz in 44 steps. Let me get the link...
http://binkster.net/extras.shtml
Okay so you can go there and see what I am talking about. I played all tracks. Wow thats annoying. But it was neat to. I posted what I heard on another forum and here is what I said there:
"So, Anyway I just played the audio cd. Actually was sitting down to see what frequency I was listening to. I have to go to the guys site and get the TOC for the disc. Tracks 11-44 are frequencys and my Audio Nirvanas may have been producing track 44 but I couldnt hear anything. I could hear up to 43. They play all but 44. So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything. So I will be right back. I have to check what the frequency of those are...........................................................
Okay. Neat 🙂 Looks like I can hear 16kHz. The ears are not failing me yet. I should go find some 17, 18, 19kHz. The driver is supposed to take a nosedive at 17kHz so I suppose that might not do me much good to try. Could test it on the Fostex I think though just to see what I can hear. Then we have
#11 16Hz
#12 20Hz
#13 25Hz
#14 31.5Hz
#15 40Hz
So the driver in the Bass Reflex box is producing 40Hz with authority and it specs state that the Fs is 37Hz I think. Lemme check.... Nope, I am wrong. The Fs is 33.8Hz. Pretty believable from what I just heard and it tries to go lower. It actually plays the 25Hz. Hmm, maybe I need to read up on what Fs is. My definition may be different than reality. I wonder if the BR enclosure is helping it get lower than its Fs. Guess it depends on how they tested it.
So there you and there I have it. I am satisfied 🙂 That was cool."
So it plays something I can hear from 25Hz up but has authority at somewhere between 31.5Hz and 40Hz.
Uriah
I just downloaded an audio test cd last night and played it a few minutes ago. It goes from 16Hz to 20kHz in 44 steps. Let me get the link...
http://binkster.net/extras.shtml
Okay so you can go there and see what I am talking about. I played all tracks. Wow thats annoying. But it was neat to. I posted what I heard on another forum and here is what I said there:
"So, Anyway I just played the audio cd. Actually was sitting down to see what frequency I was listening to. I have to go to the guys site and get the TOC for the disc. Tracks 11-44 are frequencys and my Audio Nirvanas may have been producing track 44 but I couldnt hear anything. I could hear up to 43. They play all but 44. So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything. So I will be right back. I have to check what the frequency of those are...........................................................
Okay. Neat 🙂 Looks like I can hear 16kHz. The ears are not failing me yet. I should go find some 17, 18, 19kHz. The driver is supposed to take a nosedive at 17kHz so I suppose that might not do me much good to try. Could test it on the Fostex I think though just to see what I can hear. Then we have
#11 16Hz
#12 20Hz
#13 25Hz
#14 31.5Hz
#15 40Hz
So the driver in the Bass Reflex box is producing 40Hz with authority and it specs state that the Fs is 37Hz I think. Lemme check.... Nope, I am wrong. The Fs is 33.8Hz. Pretty believable from what I just heard and it tries to go lower. It actually plays the 25Hz. Hmm, maybe I need to read up on what Fs is. My definition may be different than reality. I wonder if the BR enclosure is helping it get lower than its Fs. Guess it depends on how they tested it.
So there you and there I have it. I am satisfied 🙂 That was cool."
So it plays something I can hear from 25Hz up but has authority at somewhere between 31.5Hz and 40Hz.
Uriah
That's pretty cool Uriah,
And great timing, as I'm having to decide on enclosures now for the Super Cast 12. It's Fs = 36.427 - just a bit higher than the Super 12. Maybe this information you're reporting can mean something to GM and Scottmoose.
For a second till I visited the site I thought maybe #1-#10 were like 5Hz up... Gee, you might get flak on "hearing" 16Hz though - What does the unhearable sound like? 🙂
Yes, CSA made a point of having their BR's go to 40 with authority. However it's supposed to be the nature of a BR to enable that. The question then becomes: at what cost to quality? Apparently, not much in this case - you're quite happy with all the frequencies.
I was wondering, though, what would happen if you put damping in your vent? Have you tried that already?
Jerry
And great timing, as I'm having to decide on enclosures now for the Super Cast 12. It's Fs = 36.427 - just a bit higher than the Super 12. Maybe this information you're reporting can mean something to GM and Scottmoose.
For a second till I visited the site I thought maybe #1-#10 were like 5Hz up... Gee, you might get flak on "hearing" 16Hz though - What does the unhearable sound like? 🙂
Yes, CSA made a point of having their BR's go to 40 with authority. However it's supposed to be the nature of a BR to enable that. The question then becomes: at what cost to quality? Apparently, not much in this case - you're quite happy with all the frequencies.
I was wondering, though, what would happen if you put damping in your vent? Have you tried that already?
Jerry
Scottmoose said:
Thank you Scottmoose,
I have to apologize to GM and yourself. I feel I've been tiresome in asking if there is any significant difference in sound quality between these options. I have to reveal that my sig other has claimed the right that if there is none she be allowed to have the smaller of the choices. So far that's GM's 1.8 cu.ft. TL.
The 3.5 cu.ft damped vent BR goes down a lot more than 80Hz. It delivers wonderfully on my original request that I be able to cross not just at 80Hz but even 60Hz if possible and I've always appreciated any difference in size this necessitated. It also seems the easier build for a 1st-timer - including messing with the vent damping by ear.
Only recently, after much reading, have I come to appreciate the value of relieving the driver, as GM describes it, of the majority of the high excursion BW when crossing closer to 80Hz. I feel I have no choice but to give up being able to cross my sub any lower than that. I was too idealistic about FR drivers... Or maybe "ignorant" would be the word.
That said, in post #151 after describing his 1.87 cu.ft. TL, GM said of the 3.5:
Before I place myself at the mercy of my spouse, may I ask about this possibility? Or whether it would be bad form to ask if, relieved of the requirement for a lower extension than 80Hz altogether, you would have originally preferred a different approach?
Jerry
Kofi, it seems we will have to wait for someone to design nice horns for these things some day... I'm not sure 40Hz is going to do it for me, and I'm reasonably sure I do not want the adultaration, complexity and added cost of subs...yet.
I never said I heard 16Hz 🙂 I said I could SEE the driver and it is whooshing some air.
Here is what I said
" So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything."
Driver moving but me not hearing much of anything...
If you meant 16kHz then I would retort that I DEFINITELY hear 16kHzl. Without a doubt its there. TVs make a super high pitch when they power on. I have been able to hear that all my life. So I can walk in a house with the TV muted and tell if a TV is on. The old TVs anyway. The plasma doesnt make that noise.
Uriah
Here is what I said
" So as far as low end I get everything on the disc but at track 15 is when it really has authority in that tone. Tracks 11-14 play but is more like rushing air than a audio sound. When I cranked the volume a bit tracks 13 and 14 were more obviously there and 12 a bit but 11 is just the driver moving and pushing air but not me hearing much of anything."
Driver moving but me not hearing much of anything...
If you meant 16kHz then I would retort that I DEFINITELY hear 16kHzl. Without a doubt its there. TVs make a super high pitch when they power on. I have been able to hear that all my life. So I can walk in a house with the TV muted and tell if a TV is on. The old TVs anyway. The plasma doesnt make that noise.
Uriah
I'm sorry, I just wanted to be the first to ignore your precise description that you in fact did not hear anything and give you a hard time for even mentioning anything below 20Hz - seems that was the custom at some speaker manufacturer's forums I've visited in the past.
...Personally, some of my favorite melodies are played entirely with whooshing air. (Will I be banned for saying that on DIYaudio.com? 🙂 )
jerry
...Personally, some of my favorite melodies are played entirely with whooshing air. (Will I be banned for saying that on DIYaudio.com? 🙂 )
jerry
When I hooked up the Fostex it will play 40Hz and above but obviously not with the authority of the AN. And I can hear the 20kHz but its hard to find it. I have to put my ear within a few inches and move my ear around a bunch til I find the frequency and then it hurts so I wont be doing any more of that.
I was frankly very suprised to have the Fostex play those notes but it did and this is on the FE127e, a 4.5" speaker. Now, I tried to go lower and it made noise but it seemed it was higher frequency than the 40Hz plus if you got your ear real close I could hear a high frequency in there that I suspect, and dont know for sure, that it was the voice coil rubbing. Just a guess but maybe not a good thing to do, maybe fine. I dont know about the mechanics of it and what is/isnt okay.
Uriah
BTW what I was hearing on 12 and 13 with the AN ( so this would be frequecies 20 and 25Hz may actually be noise generated by the air passing the ports. I have to go back and listen again, but the Fostex making a noise that seemed to be higher frequency than what was supposed to be playing on 11, 12, 14, 15 made me think to listen again to the AN and now suspect that it might be "port noise?" I dont know, like I said I have to listen again.
I was frankly very suprised to have the Fostex play those notes but it did and this is on the FE127e, a 4.5" speaker. Now, I tried to go lower and it made noise but it seemed it was higher frequency than the 40Hz plus if you got your ear real close I could hear a high frequency in there that I suspect, and dont know for sure, that it was the voice coil rubbing. Just a guess but maybe not a good thing to do, maybe fine. I dont know about the mechanics of it and what is/isnt okay.
Uriah
BTW what I was hearing on 12 and 13 with the AN ( so this would be frequecies 20 and 25Hz may actually be noise generated by the air passing the ports. I have to go back and listen again, but the Fostex making a noise that seemed to be higher frequency than what was supposed to be playing on 11, 12, 14, 15 made me think to listen again to the AN and now suspect that it might be "port noise?" I dont know, like I said I have to listen again.
Okay, so conclusion, kinda..
track 14 is definitely being reproduced just not at the volume that 15 is. So it is reproducing 31.5Hz and I can hear it for sure. When I go down to track 13, 12, 11 the speaker is flexing and when you increase the volume the reflection of the light off of the surround shows it almost flattening out. Its definitely moving a lot and if you put your hand on it you get slapped a bit. The sound, though, and its not the "port noise" I suspected... it seems higher pitch/frequency than what it is supposed to be. Maybe it is some artifact of the enclosure. I dont know whats going on. So the woofer moves like mad and I hear a tone but it just seems that the tone is higher than tracks 14 and 15. You will see what I mean when you get yours and maybe you can help explain it better especially if you have an spl meter or better yet a scope that can show if more than one frequency is being generated.
Uriah
track 14 is definitely being reproduced just not at the volume that 15 is. So it is reproducing 31.5Hz and I can hear it for sure. When I go down to track 13, 12, 11 the speaker is flexing and when you increase the volume the reflection of the light off of the surround shows it almost flattening out. Its definitely moving a lot and if you put your hand on it you get slapped a bit. The sound, though, and its not the "port noise" I suspected... it seems higher pitch/frequency than what it is supposed to be. Maybe it is some artifact of the enclosure. I dont know whats going on. So the woofer moves like mad and I hear a tone but it just seems that the tone is higher than tracks 14 and 15. You will see what I mean when you get yours and maybe you can help explain it better especially if you have an spl meter or better yet a scope that can show if more than one frequency is being generated.
Uriah
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