yyyyyyyeeeeeeeoooooowwwwwwiiiiiiieee. What happened to this thread?
(monopole low bass at the bottom of dipole full range = goodness)
Ribbon Project
(monopole low bass at the bottom of dipole full range = goodness)
Ribbon Project
AJinFLA said:Chops,
my reaction is more about your 14179 thread in addition to what you said in this thread.
Chops, thread 14179 post#200
Hmm, must have got it to work eventually huh? You didn't make up those numbers by chance no? Of course not.
Now you do know that measuring a dipole in room with a non-gated system can be rather tricky. But of course you do.
Chops, thread 14179 post#172
If you are not some kind of comedian then you might see where I would think you have a severe lack of knowledge here right? It almost sounded like you were implying that SL might be an idiot for using the Peerless rather than your wonderful Pyles. But of couse youre not. Are you?
The efficiency of the driver has zero to do with max spl. Fundamental absence of how loudspeakers work? Not sure why I said that.
Do you understand the difference between "extend down to" 20hz and "high, undistorted SPL" between 40 to 20hz? A six inch driver can "extend down to" 20hz. So what? If you can figure out the difference, then you just might grasp why several people, uncluding SL have "suggested" to you that a monopole sub below 40hz is beneficial.
Chops, thread 14179, post#381
Almost sounds like it might have sank in there. Before you post in this thread of course.
Yes, I know.
Good night.
Cheers,
AJ
And your point is.....
Remember, when I started that thread, I was learning and had never heard or dealt with dipole subwoofers before.
Go through that old thread of mine and find the picture of the EQ I was using and see how very little EQing those subs needed. And where I did EQ the subs a little, it was up towards the crossover point, NOT down at 45Hz and 20Hz to help "boost" the output. Are you going to argue with me on that?
Also, I went by SLs driver specs for a dipole sub, as far as needing a high Qts and making a larger baffle for better low end response. Are you going to argue with me on this too?
The Peerless has a low Qts, and is always used in a small baffle, which is the exact opposite of what is required, thus needing a lot of EQ on the LOW end to compensate. Are you doing to deny this?
You can throw all the technical jargon and equations and reasons why those subs shouldn't have worked CLEANLY and LOUDLY all the way down to 20Hz all you want. You can dig up all the stupid things I might have said in my old thread. I DON'T CARE!
The fact of the matter is that my dipoles DID in fact do what I say they did. Why? I don't know, I don't care, but they did.
If you're so freakin' concerned about it, then why not go out and buy four of those Pyle drivers, build the baffles to the specs that I built mine, and test the darn things for yourself?! Then maybe you'll shut up and lay off my back about all of this. Heck, I'll sell you my Pyle drivers real cheap just so you can try them out.
Some things can't be explained and I guess this is one of them. So sue me!
Now like I said, leave me alone!
I admit that I do not know much about speakers but have been building OB's now for quite a few years. I have made a lot of mistakes but the one thing that I have learned is that the bass drivers do not move much at all. I use 2 x 18"bass drivers on small baffles a side. I don't need to EQ at all. I use as high a QTS driver as I can find. My 18" QTS is about .9 and with a 2.2 ohm series resistor no EQ is necessary. Xmax is 4mm but I cannot bottom the woofers whatever I play and as loud as I can. Why the woofers move less than in a vented box I do not know. My new effort will use 4 x 15" with a QTS of 1.26. Low Q drivers are a waste of time IMHO on a OB as huge EQ is required and they then do not sound that great compared to cheap high Q pro drivers. Just my 2 cents.
Well,
presented with this overwhelming and incontrovertible scientific evidence by folks such as Chops and Peter, I'm now starting to have my doubts about SL's wisdom (much less my ears) in these matters. Never mind his ramblings about distortion, group delay, WAF, etc.
It would now appear that the Orions (or John K's NaO's for that matter) could make a quantum leap forward, were SL to ditch those waste of time, stupid, low Qts Peerless junk subwoofers. It's hard to imagine what he could have been thinking in the first place.
They quite obviously don't sound anywhere near as good as cheap, high Q, low xmax Pro drivers, which, even displacing less air, have greater output for the same sized baffle. Remember, the really important thing is, little, or better yet no eq. Tools of the devil those things.
I'm now thinking of ditching my Peerless subs and building something the size of a medium size refrigerator, like Chops does with such great success. Or was that use to do? I wonder what happened?
Anyway, Peter, you're going to fit four 15's in a shoebox I imagine? Live singly in a small apartment do we? Do you have a suggestion for any particular driver?
Or should I just look for any low xmax pro driver with weak motor strength? Should I get the one with the highest amount of non-linear distortion? Do they publish any data other than the price with these cheap drivers? Is group delay something that happens when the train is late? Does any of this matter as long as an anonymous internet person "says" X or Y "sounds good"?
Graphs and equations have a way of really making my head hurt. I think I like yours and Chops way much better. Greatly simplifies matters when I can just look at a pic of a graphic eq and say "yup, it must be true".
I probably won't get anything selling the Peerless, but my DCX, since no eq is best, should fetch me a few dollars from some sucker.
Please forgive me for being so weak minded as to have believed a so-called (but well known) engineer like SL, rather than the real experts, such as anonymous users of internet forums such as this. How much more delusional could I get than that?
Cheers,
AJ
presented with this overwhelming and incontrovertible scientific evidence by folks such as Chops and Peter, I'm now starting to have my doubts about SL's wisdom (much less my ears) in these matters. Never mind his ramblings about distortion, group delay, WAF, etc.
It would now appear that the Orions (or John K's NaO's for that matter) could make a quantum leap forward, were SL to ditch those waste of time, stupid, low Qts Peerless junk subwoofers. It's hard to imagine what he could have been thinking in the first place.
They quite obviously don't sound anywhere near as good as cheap, high Q, low xmax Pro drivers, which, even displacing less air, have greater output for the same sized baffle. Remember, the really important thing is, little, or better yet no eq. Tools of the devil those things.
I'm now thinking of ditching my Peerless subs and building something the size of a medium size refrigerator, like Chops does with such great success. Or was that use to do? I wonder what happened?
Anyway, Peter, you're going to fit four 15's in a shoebox I imagine? Live singly in a small apartment do we? Do you have a suggestion for any particular driver?
Or should I just look for any low xmax pro driver with weak motor strength? Should I get the one with the highest amount of non-linear distortion? Do they publish any data other than the price with these cheap drivers? Is group delay something that happens when the train is late? Does any of this matter as long as an anonymous internet person "says" X or Y "sounds good"?
Graphs and equations have a way of really making my head hurt. I think I like yours and Chops way much better. Greatly simplifies matters when I can just look at a pic of a graphic eq and say "yup, it must be true".
I probably won't get anything selling the Peerless, but my DCX, since no eq is best, should fetch me a few dollars from some sucker.
Please forgive me for being so weak minded as to have believed a so-called (but well known) engineer like SL, rather than the real experts, such as anonymous users of internet forums such as this. How much more delusional could I get than that?
Cheers,
AJ
AJ, nobody is is claiming that SL et al are wrong!
We are talking two different things here. The Orion's are undoubtedly top-class speakers but at a top-class price. What people here are trying to do is build something open-baffle that sounds good for the money spent on them.
I too would love a pair of Orions in my room but my budget dictates that I have to use a different approach, ie cheaper drivers.
I would never question SL on the subject of OB's but I don't know him and his philosophy. For all I know he is a perfectionist who wants his speakers to measure as well as possible and sound great too. But those of us not seeking perfection will be happy to compromise on the drivers providing it still sounds OK (even if the theory side of it doesn't hold up).
The bottom line is if you have 1000 USD to spend you can't have a pair if Orions but you can have an alternative design using cheaper drivers. Now, they may not sound as good as the Orions but they sure will sound better than nothing!
We are talking two different things here. The Orion's are undoubtedly top-class speakers but at a top-class price. What people here are trying to do is build something open-baffle that sounds good for the money spent on them.
I too would love a pair of Orions in my room but my budget dictates that I have to use a different approach, ie cheaper drivers.
I would never question SL on the subject of OB's but I don't know him and his philosophy. For all I know he is a perfectionist who wants his speakers to measure as well as possible and sound great too. But those of us not seeking perfection will be happy to compromise on the drivers providing it still sounds OK (even if the theory side of it doesn't hold up).
The bottom line is if you have 1000 USD to spend you can't have a pair if Orions but you can have an alternative design using cheaper drivers. Now, they may not sound as good as the Orions but they sure will sound better than nothing!
Um, Nuuk,
The last one sounded more like a "statement" rather than "opinion", no?
Opinion? Are we reading the same posts?
I'm fine with that and spending less money. Just don't make a lot of ridiculous claims - as fact - when you do.
Say they sound fabulous, without resorting to calling the "perfectionist" method as somehow inferior. Thats just plain dumb.
Cheers,
AJ
I believe there are actually two points:
*uncompressed sound because of lack of enclosure
*dipole sound
Unfortunately I never had the opportunity to listen to an infinite baffle setting with drivers in a wall between two rooms, but I find that my OBs had not only more bass, but also better imaging, when I added side walls.
*uncompressed sound because of lack of enclosure
*dipole sound
Unfortunately I never had the opportunity to listen to an infinite baffle setting with drivers in a wall between two rooms, but I find that my OBs had not only more bass, but also better imaging, when I added side walls.
Well I know what was said but I don't think they were really running down SL but speaking from their own experience. I'll agee that it was a little opinionated but that's what forums are for.
You have picked out bits to back your case but what about the 'IMHO' bit and 'why I think'?
Anyway, I bet we all want the Orion performance, (or something close to it) for less money so let's listen to all suggestions and take it from there.
I have nearly got something (new) to show in this thread and a few questions too!
You have picked out bits to back your case but what about the 'IMHO' bit and 'why I think'?
Anyway, I bet we all want the Orion performance, (or something close to it) for less money so let's listen to all suggestions and take it from there.
I have nearly got something (new) to show in this thread and a few questions too!
AJ, just a couple of points. I am not anonymous I use my real name and area in my posts.Next I did say that I am no expert just a long time builder of OB's.I try things and listen.
It would be good to talk to another OB expert, namely Carver. He used lots of very high Q (OTS of 3 ? )drivers in his Amazing speakers no EQ I believe. This is just another way of doing things.No one way is correct. Results count.Both ways obviously work. I will say this again as others have. Using cheap high Q drivers works well and the cones hardly move and give amazing quality and quantity of bass.Just use lots of cone area.
My new speakers are small enough about 16' wide and 45" tall. 2x 15" and one Visaton 9" driver a side.Will go to only about 40-50 Hz but that is all I expect.
This argunent reminds me of my main intersest, SE amps. Years ago the experts were tell us SE amps are crap. I liked them and built them, and was amazed what they could do . I had 3 watts driving Accustat 6's to good levels and it sounded great.The experts said it could not be done.
There is something going on here that is not in the theory books, just as SE amps proved. Now look at Pass 1st watt sand amps. QED.
It would be good to talk to another OB expert, namely Carver. He used lots of very high Q (OTS of 3 ? )drivers in his Amazing speakers no EQ I believe. This is just another way of doing things.No one way is correct. Results count.Both ways obviously work. I will say this again as others have. Using cheap high Q drivers works well and the cones hardly move and give amazing quality and quantity of bass.Just use lots of cone area.
My new speakers are small enough about 16' wide and 45" tall. 2x 15" and one Visaton 9" driver a side.Will go to only about 40-50 Hz but that is all I expect.
This argunent reminds me of my main intersest, SE amps. Years ago the experts were tell us SE amps are crap. I liked them and built them, and was amazed what they could do . I had 3 watts driving Accustat 6's to good levels and it sounded great.The experts said it could not be done.
There is something going on here that is not in the theory books, just as SE amps proved. Now look at Pass 1st watt sand amps. QED.
Peter,
you mean the Carver Amazings like I used to own LOL. You think the Carver has better bass than the Peerless XLS12 (Qts 0.21!) that I currently own ? I seriously question whether you (or Chops) have heard a low distortion driver like the XLS12 or the ones used in an Orion. Have you?
Perhaps this is a large part of the problem. It is clear to me now why the low Q drivers are "a waste of time" to you, rather than a waste of money - which I could understand. You need a high Q, high efficiency driver to match that flea amp and lack of eq. The cheapo pro driver fits this criteria by default, not by any "great sound" or even "cost" merits. You are absolutely correct that the Peerless is unsuitable there. Just about any good, high performance woofer would be. Even the good HE, low distortion pro drivers usually have low Q due to their motor strength. I don't know if I have ever seen a HE, high Q driver that wasn't a cheap, low performance model. Perhaps they exist. Here is a high Q, high performance driver http://www.soundsplinter.com/rls_series/rls15_inch_LMT_DIY_car_home_subwoofer_information.html, but note the sensitivity.
But this has nothing to do with Qts, does it?
Rather, what you are really saying is, due to the fact that you choose to use a 2watt amp, you are pigeon-holed into using crappy, high Q pro drivers, then proclaiming them to have great sound - by necessity.
It may have nothing to do with speaker cost or how good the speaker sounds, low Q or not, but rather driven entirely by your very own choice of amplifiers.
Taken in this context, your statements about low Qts drivers and eq, make a whole lot more sense.
Cheers,
AJ
you mean the Carver Amazings like I used to own LOL. You think the Carver has better bass than the Peerless XLS12 (Qts 0.21!) that I currently own ? I seriously question whether you (or Chops) have heard a low distortion driver like the XLS12 or the ones used in an Orion. Have you?
Perhaps this is a large part of the problem. It is clear to me now why the low Q drivers are "a waste of time" to you, rather than a waste of money - which I could understand. You need a high Q, high efficiency driver to match that flea amp and lack of eq. The cheapo pro driver fits this criteria by default, not by any "great sound" or even "cost" merits. You are absolutely correct that the Peerless is unsuitable there. Just about any good, high performance woofer would be. Even the good HE, low distortion pro drivers usually have low Q due to their motor strength. I don't know if I have ever seen a HE, high Q driver that wasn't a cheap, low performance model. Perhaps they exist. Here is a high Q, high performance driver http://www.soundsplinter.com/rls_series/rls15_inch_LMT_DIY_car_home_subwoofer_information.html, but note the sensitivity.
But this has nothing to do with Qts, does it?
Rather, what you are really saying is, due to the fact that you choose to use a 2watt amp, you are pigeon-holed into using crappy, high Q pro drivers, then proclaiming them to have great sound - by necessity.
It may have nothing to do with speaker cost or how good the speaker sounds, low Q or not, but rather driven entirely by your very own choice of amplifiers.
Taken in this context, your statements about low Qts drivers and eq, make a whole lot more sense.
Cheers,
AJ
Unfortunetly the peerless sub range is not a really a low distortion driver either when used near its fs. (and I believe the Orion, Phoenix, Nao, etc. all do).
Operate any driver near its fs (above and below) and it will have problems as well.
HOWEVER, if you cut the driver near its fs (a little less than an octave above it) with a steep highpass filter and sure enough it "becomes" low distortion. (..though the filter itself may add a significant amount of distortion.) In fact any good driver will have this quality. Higher qts driver's have less of this quality though because they are essentially less linear further above and below their fs.
Graphically you can "usually" tell how linear a driver will be above and below its fs by looking at the impeadance vs. freq.. The woofer's midrange (200Hz) region usually represents its linear operation and is typically around the impeadance value of the driver's nominal impeadance (i.e. 8 ohms for an 8 ohm driver). When the impeadance starts going higher in level (say up to 100 ohms at fs), then typically distortion increases with "generally" a comensurate level of impeadance increase. (..i.e. an increase to 16 ohms for a nominal 8 ohm driver increases distortion by a modest amount whereas an increase to 32 ohms or more in the same driver signals a larger increase in distortion.)
A low qts driver will usually have a narrow impeadance peak at fs - essentially meaning that the passband of distortion is narrow. A high qts driver will have a "wider" passband of distortion.
The intersting thing though is that a wider passband of distortion from a high qts driver does not neccesarily mean the driver will have *significantly* more distorion than a low qts driver when the driver is operated as follows:
1. The driver has no highpass (no lower freq. cut-off above fs), AND
2. The driver's upper freq. response does not extend much into the midrange.
3. Excursion is kept within the driver's linear potential
4. Thermal limits are kept reasonably low (preferably with virtually all DC blocked from the VC)
In otherwords - operated as a normal woofer.
(Of course the best course of action is to know what operating range you intend to use the driver for and actually measuring its distortion levels.)
Of course NONE of the above relates to how much or little (and what type of) distortion YOU respond to. I think that most people would be SHOCKED at just how little they hear distortion DEPENDING on the freq. response of the signal.
In particular I personally don't notice lower orders of distortion (2nd and 3rd) at even relativly high levels (25% of 2nd and around 9% of third) when the loudspeaker is reproducing DIRECT sound. (i.e. a performer, singer, guitar/amp, ect.) I do however notice distortion levels that high at low freq.s when the signal is NOT reproducing direct sound (i.e. "hall sound" or recording room reflections real or virtual).
(note that when I say "notice" I mean essentially "sense somethings off")
At least for me then (an others that I've tested this on - all of which have concluded similarly), low distortion becomes MORE important at very low freq.s.
This leads me to the conclusion that drivers with fs's (operated in free air) below 40 Hz are ALL unaceptably high in distortion (..unless of course a low distortion highpass is use in the appropriate place).
Additionally, (utlizing ALL of the above information), It also suggests that subwoofer should be used that either has an fs above say 45 Hz in free air, or used in a box with the "fs" "pushed up" above 45 Hz. This allows the driver to actually operate more linearly at the expense of a comparitive increase in excursion and a resulting lower spl operating range.
We can even take this farther. Because free air operation with such a driver radically increases excursion - this is a suboptimal use of the driver unless multiple drivers are used. The same is true for sealed designs as well. A vented configuration however, (say a non-aligned bass reflex with a low port freq. taken to around 10 Hz), should allow low distortion within the 18-39 Hz range for a single driver application. (..though remember that the port has the same problems as a driver - this is why I spec'ed a 10Hz port tuning freq..)
So then - say you want a real low distortion dipole sub.. what driver operating below 40Hz (say 35Hz down to "DC"? Understanding that to have signifiants spl's we need multiple drivers (typically 4 or more depending on the driver's sd).
Perhaps the Ciare 12.00SW (assuming that the fs is "optimistic" and is really closer to 50 Hz):
http://www.ciare.com/oem/index.html
well then, just some thoughts on the topic..
Operate any driver near its fs (above and below) and it will have problems as well.
HOWEVER, if you cut the driver near its fs (a little less than an octave above it) with a steep highpass filter and sure enough it "becomes" low distortion. (..though the filter itself may add a significant amount of distortion.) In fact any good driver will have this quality. Higher qts driver's have less of this quality though because they are essentially less linear further above and below their fs.
Graphically you can "usually" tell how linear a driver will be above and below its fs by looking at the impeadance vs. freq.. The woofer's midrange (200Hz) region usually represents its linear operation and is typically around the impeadance value of the driver's nominal impeadance (i.e. 8 ohms for an 8 ohm driver). When the impeadance starts going higher in level (say up to 100 ohms at fs), then typically distortion increases with "generally" a comensurate level of impeadance increase. (..i.e. an increase to 16 ohms for a nominal 8 ohm driver increases distortion by a modest amount whereas an increase to 32 ohms or more in the same driver signals a larger increase in distortion.)
A low qts driver will usually have a narrow impeadance peak at fs - essentially meaning that the passband of distortion is narrow. A high qts driver will have a "wider" passband of distortion.
The intersting thing though is that a wider passband of distortion from a high qts driver does not neccesarily mean the driver will have *significantly* more distorion than a low qts driver when the driver is operated as follows:
1. The driver has no highpass (no lower freq. cut-off above fs), AND
2. The driver's upper freq. response does not extend much into the midrange.
3. Excursion is kept within the driver's linear potential
4. Thermal limits are kept reasonably low (preferably with virtually all DC blocked from the VC)
In otherwords - operated as a normal woofer.
(Of course the best course of action is to know what operating range you intend to use the driver for and actually measuring its distortion levels.)
Of course NONE of the above relates to how much or little (and what type of) distortion YOU respond to. I think that most people would be SHOCKED at just how little they hear distortion DEPENDING on the freq. response of the signal.
In particular I personally don't notice lower orders of distortion (2nd and 3rd) at even relativly high levels (25% of 2nd and around 9% of third) when the loudspeaker is reproducing DIRECT sound. (i.e. a performer, singer, guitar/amp, ect.) I do however notice distortion levels that high at low freq.s when the signal is NOT reproducing direct sound (i.e. "hall sound" or recording room reflections real or virtual).
(note that when I say "notice" I mean essentially "sense somethings off")
At least for me then (an others that I've tested this on - all of which have concluded similarly), low distortion becomes MORE important at very low freq.s.
This leads me to the conclusion that drivers with fs's (operated in free air) below 40 Hz are ALL unaceptably high in distortion (..unless of course a low distortion highpass is use in the appropriate place).
Additionally, (utlizing ALL of the above information), It also suggests that subwoofer should be used that either has an fs above say 45 Hz in free air, or used in a box with the "fs" "pushed up" above 45 Hz. This allows the driver to actually operate more linearly at the expense of a comparitive increase in excursion and a resulting lower spl operating range.
We can even take this farther. Because free air operation with such a driver radically increases excursion - this is a suboptimal use of the driver unless multiple drivers are used. The same is true for sealed designs as well. A vented configuration however, (say a non-aligned bass reflex with a low port freq. taken to around 10 Hz), should allow low distortion within the 18-39 Hz range for a single driver application. (..though remember that the port has the same problems as a driver - this is why I spec'ed a 10Hz port tuning freq..)
So then - say you want a real low distortion dipole sub.. what driver operating below 40Hz (say 35Hz down to "DC"? Understanding that to have signifiants spl's we need multiple drivers (typically 4 or more depending on the driver's sd).
Perhaps the Ciare 12.00SW (assuming that the fs is "optimistic" and is really closer to 50 Hz):
http://www.ciare.com/oem/index.html
well then, just some thoughts on the topic..
First of all - I'm amazed, that this thread is alive again
Because of Qts "fight" - I dunno if anyone is still interested in my "Orion for miser" project, but I decided [finally!] what speakers I'm gonna use:
- Seas 27TBFC/G [H1212]
- Seas L22RNX/P [H1252]
- 2xPeerless SLS 12
Now, let me quote SL:
http://www.linkwitzlab.com/models.htm
Look at point C3 - Equalization of low Qt woofer:
"Better yet, drivers with very low Qts < 0.5 make it possible to place two real axis poles at 20 Hz and the 3rd pole around 5 Hz, but require more elaborate equalization, because they roll off with a pole around 80 Hz in addition to the 6 dB/oct dipole roll-off..
In general, I prefer the more gradual roll-off for any woofer, because it corresponds to a more linear phase response (more uniform group delay) and that is audible. The trade-off is in low end extension."
So - he uses low Qts drivers on purpose...
best regards
L.
Because of Qts "fight" - I dunno if anyone is still interested in my "Orion for miser"
project, but I decided [finally!] what speakers I'm gonna use:- Seas 27TBFC/G [H1212]
- Seas L22RNX/P [H1252]
- 2xPeerless SLS 12
Now, let me quote SL:
http://www.linkwitzlab.com/models.htm
Look at point C3 - Equalization of low Qt woofer:
"Better yet, drivers with very low Qts < 0.5 make it possible to place two real axis poles at 20 Hz and the 3rd pole around 5 Hz, but require more elaborate equalization, because they roll off with a pole around 80 Hz in addition to the 6 dB/oct dipole roll-off..
In general, I prefer the more gradual roll-off for any woofer, because it corresponds to a more linear phase response (more uniform group delay) and that is audible. The trade-off is in low end extension."
So - he uses low Qts drivers on purpose...
best regards
L.
mrsteve wrote
"Horn-loaded bass sounds as realistic as dipole bass"
and reading these
http://www.musicanddesign.com/roomgain.html
http://www.musicanddesign.com/roomgain2.html
i wondered how does a horn pressurizes the room below the room fundamental resonance .I doe not really understand a horn but i believe a horn makes a lot of noise with a little cone movement . or does that little cone movement still result in a lot of air displacement in the horn mouth?
"Horn-loaded bass sounds as realistic as dipole bass"
and reading these
http://www.musicanddesign.com/roomgain.html
http://www.musicanddesign.com/roomgain2.html
i wondered how does a horn pressurizes the room below the room fundamental resonance .I doe not really understand a horn but i believe a horn makes a lot of noise with a little cone movement . or does that little cone movement still result in a lot of air displacement in the horn mouth?
LennyK said:First of all - I'm amazed, that this thread is alive again
Because of Qts "fight" - I dunno if anyone is still interested in my "Orion for miser"
- Seas 27TBFC/G [H1212]
- Seas L22RNX/P [H1252]
- 2xPeerless SLS 12
Now, let me quote SL:
http://www.linkwitzlab.com/models.htm
Look at point C3 - Equalization of low Qt woofer:
"Better yet, drivers with very low Qts < 0.5 make it possible to place two real axis poles at 20 Hz and the 3rd pole around 5 Hz, but require more elaborate equalization, because they roll off with a pole around 80 Hz in addition to the 6 dB/oct dipole roll-off..
In general, I prefer the more gradual roll-off for any woofer, because it corresponds to a more linear phase response (more uniform group delay) and that is audible. The trade-off is in low end extension."
So - he uses low Qts drivers on purpose...
best regards
L.
This is an "eq." matter of "summed response" looking at phase angle and group delay. In otherwords utilizing a traditional "eq." approach its better to use a lower qts driver (..perhaps without looking at filter generated distortion).
Most DIY'ers do high qts drivers that are not "eq.ed" (..at least not traditionally*), or if they are - then its nothing more than a 1st order (single inductor) approach.
So its really apples to oranges (..rather than an apples to apples comparison).
Of course he doesn't mention the amount of distortion the "eq." itself introduces. (.. well at least not there anyway)
*Note that the use of current mode amplifier operation (like the firstwatt or most tube amps) will effectivly increase gain as impeadance increases (..to an extent depending on the amp's current capability and output impeadance). IF care is taken when selecting a driver's qts "response" in free air in addition to the amplifer's current gain - you could end up with a fairly linear low freq. response without "eq.". Practically speaking though any high qts woofer with an fs below 40 Hz will be difficult to achieve a linear response.
I am considering putting my dayton rs 12" subs in either u baffles or really nice sealed boxes.
Can you give me some info as to how to think about u baffles? Things like power and frequency response. Maybe a website or something? I am having trouble finding info.
I also had a brainstorm! What if you built a dipole sub woofer and then behind the dipole you put a helmholtz resonater tuned to a low freq like twenty hz. That way the resonator would absorb some of the backwave and boost the bass response without affecting the dipole sound. Could this work?
thanks
Can you give me some info as to how to think about u baffles? Things like power and frequency response. Maybe a website or something? I am having trouble finding info.
I also had a brainstorm! What if you built a dipole sub woofer and then behind the dipole you put a helmholtz resonater tuned to a low freq like twenty hz. That way the resonator would absorb some of the backwave and boost the bass response without affecting the dipole sound. Could this work?
thanks
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