Re: Re: Hey... great to meet another Elektor reader!
Cool! There's hope yet!
I had originally gotten depressed because I used to hang around in audioasylum.com a bit, and there I found people talking about DIY DACs, but no one seemed to have a clue about the sophisticated DAC circuit published in Elektor in 2000. They'd not even heard about it, it seemed.
Thanks. This makes at least this bit very, very clear. I have a feeling a friend is using this Peerless tweeter in a Proac 2.5 lookalike box, and I'm sure now that this is a bad idea... the woofer's rear wave must be totally distorting the tweeter's delicate sound. I'll pass on what you've taught me.
Navin/Angshu/Vivek, any ideas about these Peerless India tweeters?
Tarun
planet10 said:
Cool! There's hope yet!
I had originally gotten depressed because I used to hang around in audioasylum.com a bit, and there I found people talking about DIY DACs, but no one seemed to have a clue about the sophisticated DAC circuit published in Elektor in 2000. They'd not even heard about it, it seemed.
planet10 said:
Thanks. This makes at least this bit very, very clear. I have a feeling a friend is using this Peerless tweeter in a Proac 2.5 lookalike box, and I'm sure now that this is a bad idea... the woofer's rear wave must be totally distorting the tweeter's delicate sound. I'll pass on what you've taught me.
Navin/Angshu/Vivek, any ideas about these Peerless India tweeters?
Tarun
Tarun,
The Linkwitz Orion bass section and the Thor are completely different animals. The Orion uses an H-Frame dipole bass section, as explained here:
http://www.linkwitzlab.com/proto.htm#PW1
It requires EQ for both the 6dB/octave dipole roll-off, and for the low Qts. Incidentally, a high Q woofer won't play any louder, it just needs less active EQ. Loudness is still a function of cone area and cone excursion.
The Thor is a traditional sealed monopole subwoofer in a small box that uses a Linkwitz transform to go lower.
The theory is that you use the Orion down to the lowest room resonance frequency, then bring in the Thor below that. This way the dipole bass is ued where room problems are most common, and the monopole bass comes in below that and you can take advantage of room gain.
To work out this point you divide 343 by 2 x your room's longest dimension.
Regarding my speakers, I use the same push/pull H-Frame arrangement as the Orion. This reduces distortion, but not vibration. The bass section does vibrate, but the mid panel is on a separate section which is isolated from the bass. There's a shot on my site of the two separated.
In the past I have tried different combinations of dipole bass/monopole mids and monopole bass/dipole mids. I like dipole bass/dipole mids best, partly I'm sure because it makes sense to have matching radiation patterns.
Hope this helps
Steve
The Linkwitz Orion bass section and the Thor are completely different animals. The Orion uses an H-Frame dipole bass section, as explained here:
http://www.linkwitzlab.com/proto.htm#PW1
It requires EQ for both the 6dB/octave dipole roll-off, and for the low Qts. Incidentally, a high Q woofer won't play any louder, it just needs less active EQ. Loudness is still a function of cone area and cone excursion.
The Thor is a traditional sealed monopole subwoofer in a small box that uses a Linkwitz transform to go lower.
The theory is that you use the Orion down to the lowest room resonance frequency, then bring in the Thor below that. This way the dipole bass is ued where room problems are most common, and the monopole bass comes in below that and you can take advantage of room gain.
To work out this point you divide 343 by 2 x your room's longest dimension.
Regarding my speakers, I use the same push/pull H-Frame arrangement as the Orion. This reduces distortion, but not vibration. The bass section does vibrate, but the mid panel is on a separate section which is isolated from the bass. There's a shot on my site of the two separated.
In the past I have tried different combinations of dipole bass/monopole mids and monopole bass/dipole mids. I like dipole bass/dipole mids best, partly I'm sure because it makes sense to have matching radiation patterns.
Hope this helps
Steve
The reason I suddenly mentioned the 5' is that it was a surprise to me too. I had remembered 3'. Lately I had been disappointed in the imaging and "air" of the speakers. In my first tests I had them in the middle of the room to work on them.They sounded amazing. When they were pretty much finished for the moment, I put them about 2' from the walls. I didn't make the connection, but was starting t o wonder if they were as good as I had originally thought. I have tried moving them out into the room again, and the great sound returns! Well, I guess you don't get something for nothing. My room isn't really big enough either.
I was thinking of having the woofer boxes against the wall, and have light weight baffles about 16" wide and 3.5' tall that I could easily position into the room for listening sessions.
That's why I asked about having the mid/tweet on a separate baffle and the woofer box back 3'. remember that they crossover under 200 hz. Anyone have an opinion on this? Dave?
I was thinking of having the woofer boxes against the wall, and have light weight baffles about 16" wide and 3.5' tall that I could easily position into the room for listening sessions.
That's why I asked about having the mid/tweet on a separate baffle and the woofer box back 3'. remember that they crossover under 200 hz. Anyone have an opinion on this? Dave?
There are so many questions in this thread and every answer is enlightening. So I will try to give in my share:
Dimensions of Baffle:
As I learned in another forum, width of the baffle is not the crucial criterion. Determinant is the time delay between the front wave and the back wave of the dipole speaker at the hearing position. So if you have large baffle wings like in an H-frame, their length will count (almost) double (because the backwave has to travel way back round the wing edge and way forward to the plane of the speaker).
I have dimensioned my open baffles following these thoughts. They have very small loudspeaker baffles and tilted back wings (40 and 50 cm deep). They are tilted in 90° and 45° and I don´t hear any „box“ effects until the angle between the wings becomes less than 30°.
These baffles are optically much less „intruding“ than „fat“ baffles and will certainly reach down to the 90 Hz Fs of my little 3“-woofers.
Qts:
Look for my Qts diagram in this very valuable thread und it becomes obvious why a high Q is desirable in open baffle:
http://www.diyaudio.com/forums/showthread.php?postid=208584#post208584
Subwoofer (monopole or dipole):
My OBs work with a plain BR-Subwoofer (coming in at 150 Hz). Depending on the position of the subwoofer, I have to switch the phase of the Subwoofer to 180° or back (I can only choose this 2 positions) to get the best bass. So the different characteristics of dipole and monopole radiation are an issue. But it seems that interactions with the room dimensions (especially ceiling heights) will have much more influence on the SPL in these frequency regions. I wouldn´t worry too much about the monopole/dipole combination. Best solution in any way: One dipole subwoofer for each stereo channel.
Distance from rear wall:
I agree that 5 feet is desirable. But less distance doesn´t automatically ruin the imaging. My impressions: A less reflective rear wall (Book rack etc) will help. And while you get nearer to the wall with the OBs, the imaging looses depth. The music gets pinned to the wall, while the stereo imaging remains mostly intact. Certainly I would not under-run 3 feet.
Hope I could give some handy information.
Rudolf
Dimensions of Baffle:
As I learned in another forum, width of the baffle is not the crucial criterion. Determinant is the time delay between the front wave and the back wave of the dipole speaker at the hearing position. So if you have large baffle wings like in an H-frame, their length will count (almost) double (because the backwave has to travel way back round the wing edge and way forward to the plane of the speaker).
I have dimensioned my open baffles following these thoughts. They have very small loudspeaker baffles and tilted back wings (40 and 50 cm deep). They are tilted in 90° and 45° and I don´t hear any „box“ effects until the angle between the wings becomes less than 30°.
These baffles are optically much less „intruding“ than „fat“ baffles and will certainly reach down to the 90 Hz Fs of my little 3“-woofers.
Qts:
Look for my Qts diagram in this very valuable thread und it becomes obvious why a high Q is desirable in open baffle:
http://www.diyaudio.com/forums/showthread.php?postid=208584#post208584
Subwoofer (monopole or dipole):
My OBs work with a plain BR-Subwoofer (coming in at 150 Hz). Depending on the position of the subwoofer, I have to switch the phase of the Subwoofer to 180° or back (I can only choose this 2 positions) to get the best bass. So the different characteristics of dipole and monopole radiation are an issue. But it seems that interactions with the room dimensions (especially ceiling heights) will have much more influence on the SPL in these frequency regions. I wouldn´t worry too much about the monopole/dipole combination. Best solution in any way: One dipole subwoofer for each stereo channel.
Distance from rear wall:
I agree that 5 feet is desirable. But less distance doesn´t automatically ruin the imaging. My impressions: A less reflective rear wall (Book rack etc) will help. And while you get nearer to the wall with the OBs, the imaging looses depth. The music gets pinned to the wall, while the stereo imaging remains mostly intact. Certainly I would not under-run 3 feet.
Hope I could give some handy information.
Rudolf
Attachments
Hi Tarun and Dave
Elektor is getting pretty hard to find on newstands in the UK (especially in the wilds of Cumbria). Always been impressed by the quality of their projects (their PCBs are a marvel to behold). I'll see if I can dig out the reference to their dipole project. Most of their speaker projects seem to be by the same guy. The last one I remember reading was a rear-loaded horn speaker using (I think) McKenzie drivers.
I'll be interested to hear how the dipole JX92s progress - I've just bought a pair of these drivers myself. (Although the dipole idea is pretty academic in my case given the size and layout of room.)
Colin
Elektor is getting pretty hard to find on newstands in the UK (especially in the wilds of Cumbria). Always been impressed by the quality of their projects (their PCBs are a marvel to behold). I'll see if I can dig out the reference to their dipole project. Most of their speaker projects seem to be by the same guy. The last one I remember reading was a rear-loaded horn speaker using (I think) McKenzie drivers.
I'll be interested to hear how the dipole JX92s progress - I've just bought a pair of these drivers myself. (Although the dipole idea is pretty academic in my case given the size and layout of room.)
Colin
I looked at the page, but I can't find any mention that this is the woofer design used for the Orion. I guess you know more about the Orion than I found on that Website. In any case, this is exactly the design you've used for your speakers, right?sfdoddsy said:
Yes, agreed. I meant that high Qts will probably allow the driver to move more easily in an OB design without bottoming out, given the absence of any stiffening from a box.
I am guilty of confusing all of you here. In my last post, when I wrote "Thor subwoofer", I meant the woofer which is part of the Phoenix (not the Orion, the Phoenix). The Phoenix woofer has two drivers in vibration-cancelling mode, but the box as a whole behaves like a dipole, right?
Really sorry about this mix-up.
Yes, I saw those pics. Your speakers and Variac's Basszilla have been major inspirations. I just don't know whether I'll get good results without your Driverack, though.
Cool. Thanks. Makes sense to me. One last question about your design choices: why did you choose the H-frame over the Phoenix woofer design?
You know, the biggest resistance I feel today to trying out the dipole design is not so much the electronics as the need to keep five feet of clear space behind the speakers; I discovered this in this thread from Variac's post. Makes most rooms very hard to lay out, doesn't it?
Tarun
The minimum is 3 feet behind, according to Linkwitz.
I chose the H-Frame construction rather than the W-Frame of the Phoenix for a couple of reasons. Firstly I am very clumsy and an H-frame is easier to build. Secondly I wanted to have the speakers be a one piece design, which is a little trickier with a W-frame.
Cheers
Steve
I chose the H-Frame construction rather than the W-Frame of the Phoenix for a couple of reasons. Firstly I am very clumsy and an H-frame is easier to build. Secondly I wanted to have the speakers be a one piece design, which is a little trickier with a W-frame.
Cheers
Steve
Variac and Rudolf,
Thanks for the inputs. In particular, Rudolf's baffles were a very interesting counterpoint to the "large, flat, and ungainly" I was thinking of so far. I may not need your larger baffles, because I'm toying with a higher XO frequency, maybe something like 300Hz. Is there any reason to believe 300Hz will be too high?
I'm actually toying with the idea of building some prototypes for a friend, using really inexpensive drivers. (They're prototypes, remember?) The local Philips India brand sells some drivers, including an 8" dual-cone "full-range", for about USD 5.00 each. I'll use this for the mids, from 300Hz to maybe 5KHz. Then bring in a dome tweeter using a single cap. The 8" and the dome tweeter will be on an OB, dimensions and shape to be experimented with.
Below 300Hz, I'll try building either a two-driver H-frame like Steve's or a one-driver box (sealed, perhaps). This too depends on money. And Dave's posting about being able to keep the woofer boxes further back seem like a good idea. If the woofer box is half-XO-wavelength back, does this mean I'll have to have the woofer 180-deg out of phase with the mid? I guess I will, right? And is there a relationship between the lowest frequency my OB panel handles and the minimum distance from the rear wall?
The 300Hz XO will be active. Inexpensive LM3875 chip amps will be used for power. I'll use the Jordans once I learn from these experiments.
Why do people who build twin-driver H-frame woofers keep the woofers vertical? Won't the boxes be a bit less vibration-prone if kept on their sides? Yet another of my newbie questions...
I'll let you know when we begin work. For now, I think any inputs about any of this are desperately sought, with a newbie-style open-mouthed eagerness.
Tarun
Thanks for the inputs. In particular, Rudolf's baffles were a very interesting counterpoint to the "large, flat, and ungainly" I was thinking of so far. I may not need your larger baffles, because I'm toying with a higher XO frequency, maybe something like 300Hz. Is there any reason to believe 300Hz will be too high?
I'm actually toying with the idea of building some prototypes for a friend, using really inexpensive drivers. (They're prototypes, remember?) The local Philips India brand sells some drivers, including an 8" dual-cone "full-range", for about USD 5.00 each. I'll use this for the mids, from 300Hz to maybe 5KHz. Then bring in a dome tweeter using a single cap. The 8" and the dome tweeter will be on an OB, dimensions and shape to be experimented with.
Below 300Hz, I'll try building either a two-driver H-frame like Steve's or a one-driver box (sealed, perhaps). This too depends on money. And Dave's posting about being able to keep the woofer boxes further back seem like a good idea. If the woofer box is half-XO-wavelength back, does this mean I'll have to have the woofer 180-deg out of phase with the mid? I guess I will, right? And is there a relationship between the lowest frequency my OB panel handles and the minimum distance from the rear wall?
The 300Hz XO will be active. Inexpensive LM3875 chip amps will be used for power. I'll use the Jordans once I learn from these experiments.
Why do people who build twin-driver H-frame woofers keep the woofers vertical? Won't the boxes be a bit less vibration-prone if kept on their sides? Yet another of my newbie questions...
I'll let you know when we begin work. For now, I think any inputs about any of this are desperately sought, with a newbie-style open-mouthed eagerness.
Tarun
What kind of dipole bass?
What kind of dipole bass? The Phoenix type or the Orion type? (It appears that there are just two types of dipole woofers, and both have been covered by SL's designs.)
I've asked Steve this too, but are there any reasons to prefer one over the other? To put it more precisely, is there any reason to prefer the H-frame over the "other" type (what do you call it? I guess we can call it the "Phoenix" design), other than simplicity of assembly? There's an obvious reason to prefer the "other" type.... vibration cancellation.
And any thoughts about the rear wave issues when combining bipole with dipole? Also, by using the dipole bass as a stand for the bipole, do you intend to keep the bipole bass at a height? Isn't it better to keep these bass boxes low, specially when you want room reinforcement, as in your super-low-frequency bipole?
Tarun
navin said:
What kind of dipole bass? The Phoenix type or the Orion type? (It appears that there are just two types of dipole woofers, and both have been covered by SL's designs.)
I've asked Steve this too, but are there any reasons to prefer one over the other? To put it more precisely, is there any reason to prefer the H-frame over the "other" type (what do you call it? I guess we can call it the "Phoenix" design), other than simplicity of assembly? There's an obvious reason to prefer the "other" type.... vibration cancellation.
And any thoughts about the rear wave issues when combining bipole with dipole? Also, by using the dipole bass as a stand for the bipole, do you intend to keep the bipole bass at a height? Isn't it better to keep these bass boxes low, specially when you want room reinforcement, as in your super-low-frequency bipole?
Tarun
Typical cap value for single-cap tweeter XO?
Dear all,
If I have 8-ohm mid and tweeter, what cap value will give a high-pass at, say, 5K or 10K for the tweeter? In other words, what range of cap values should I begin experimenting with? While on the subject, do you think metallised polyester is a good cap type? I simply can't get any of the fancy types (paper in oil and what not) in Bombay unless I import. And this is a prototype, remember?
I remember Dave on Planet 10 posting on another thread that he starts with a small cap value and keeps increasing it, listening extensively, till he finds the tweeter "getting in the way" of the mid. That's when he backs off and freezes the cap value. Seems as good a way to start playing around as any. (Errors while quoting Dave are all my doing, etc.)
If there's a significant sensitivity difference between the tweeter and the mid, can I put a small resistor in series with the tweeter? (I usually seem to find tweeters more sensitive than the larger drivers, rarely the other way round.)
And finally, to keep you all bored and irritated
, here's the newbie question: what's an L-pad? I've read about it many times, and it appears to be a variable attenuation device of some sort, but I don't know what it is. Is it a high-power-rated rheostat? (Can we have a "newbies-only" forum where such newbie questions can be asked and answered? That way, we guys can keep out of the rest of your hair, assuming you have lots of it.)
Tarun
Dear all,
If I have 8-ohm mid and tweeter, what cap value will give a high-pass at, say, 5K or 10K for the tweeter? In other words, what range of cap values should I begin experimenting with? While on the subject, do you think metallised polyester is a good cap type? I simply can't get any of the fancy types (paper in oil and what not) in Bombay unless I import. And this is a prototype, remember?
I remember Dave on Planet 10 posting on another thread that he starts with a small cap value and keeps increasing it, listening extensively, till he finds the tweeter "getting in the way" of the mid. That's when he backs off and freezes the cap value. Seems as good a way to start playing around as any. (Errors while quoting Dave are all my doing, etc.)
If there's a significant sensitivity difference between the tweeter and the mid, can I put a small resistor in series with the tweeter? (I usually seem to find tweeters more sensitive than the larger drivers, rarely the other way round.)
And finally, to keep you all bored and irritated
, here's the newbie question: what's an L-pad? I've read about it many times, and it appears to be a variable attenuation device of some sort, but I don't know what it is. Is it a high-power-rated rheostat? (Can we have a "newbies-only" forum where such newbie questions can be asked and answered? That way, we guys can keep out of the rest of your hair, assuming you have lots of it.)Tarun
you can start with 2.2uf, 3.3uf, 4.7uf. i usually find by 4.7uf the tweeter is "getting in the way of the mid" unless the mid is larger than 6" and needs to rolled of earlier in which case i move to 9db+ slopes using a large (0.5mh+) inductor with the tweeter. another odd effect i notice is that if teh cap is too large say 10uf and teh inductor is too small say .2mh you get a sort of ringing effect. so what i do is keep the value of caps in uf max 10 times that of teh value of the inductor (2nd order only) in mh. so for a 6.8uf cap i would use a 0.7mh inductor and for a 9uf cap (6.8+2.2) i use a 1mh (DCR 0.2 ohms). while it is nice to keep the DCR if inductors down this needs to be done for series inductors more than parallel.
u can add a resistor in tweeter ckt. 2 ways either before cap or after cap (bet cap and tweeter) . however if you use after cap then your freq. changes as the cap works on total impedance. if you want to tinker use the resistor before the cap.
an L pad in most cases is 2 resistors one in series with the driver and one in parallel. i call them Rs and Rp. Usually I would put the Rp closer to the driver but i have seen it used the other way. i just feel i can mentally caculate effective db loss and effective R (Re) easier with Rp closer to driver. so for 8 ohm driver if u use Rp = 8 and Rs = 4. db loss will be 6db. Re = 8.
when u start tinkering it is very frustrating ; so if you get frustrated stop and relax and get back after a week, 2 or 3. remember we are searching for the holy grail so untill you find it you will get frustrated.
u can add a resistor in tweeter ckt. 2 ways either before cap or after cap (bet cap and tweeter) . however if you use after cap then your freq. changes as the cap works on total impedance. if you want to tinker use the resistor before the cap.
an L pad in most cases is 2 resistors one in series with the driver and one in parallel. i call them Rs and Rp. Usually I would put the Rp closer to the driver but i have seen it used the other way. i just feel i can mentally caculate effective db loss and effective R (Re) easier with Rp closer to driver. so for 8 ohm driver if u use Rp = 8 and Rs = 4. db loss will be 6db. Re = 8.
when u start tinkering it is very frustrating ; so if you get frustrated stop and relax and get back after a week, 2 or 3. remember we are searching for the holy grail so untill you find it you will get frustrated.
Here's a reference for capacitor size. I am using a 1.5 uF at the moment since I have a full range type driver as you do. The numbers Navin gave you are more for normal midranges I think.
Remember with a 6dB slope, the tweeter has an effect waaay below the crossover frequency.
http://www.carstereo.com/help2/Articles.cfm?id=1
Can anyone confirm the accuracy?
I believe that in almost any crossover issue, you halve the value and it doubles the crossover freq. (and vice versa)
An L-pad in its simplest and best form is 2 resistors, one inline, one across the 2 terminals
The point is that they keep the impedence that the amp sees at 8 ohms. If you just stuck one resistor inline the impedence would go up.They are also made as a device that looks similar to a potentiometer.The wiper contact creates 2 different resistances as it moves along a coil.
These resistances are in the correct proportion to keep the impedence looking like 8 ohms to the amp. Of course the 2 resistor approach is the purist way, but I'm having fun with the adjustable version. When I decide what the best position is, I will measure the 2 resistances and replace it with the 2 premium resistors
Here is an L-pad design page
http://www.solen.ca/
click on "Design"
Remember with a 6dB slope, the tweeter has an effect waaay below the crossover frequency.
http://www.carstereo.com/help2/Articles.cfm?id=1
Can anyone confirm the accuracy?
I believe that in almost any crossover issue, you halve the value and it doubles the crossover freq. (and vice versa)
An L-pad in its simplest and best form is 2 resistors, one inline, one across the 2 terminals
The point is that they keep the impedence that the amp sees at 8 ohms. If you just stuck one resistor inline the impedence would go up.They are also made as a device that looks similar to a potentiometer.The wiper contact creates 2 different resistances as it moves along a coil.
These resistances are in the correct proportion to keep the impedence looking like 8 ohms to the amp. Of course the 2 resistor approach is the purist way, but I'm having fun with the adjustable version. When I decide what the best position is, I will measure the 2 resistances and replace it with the 2 premium resistors
Here is an L-pad design page
http://www.solen.ca/
click on "Design"
For some bizarre reason my previous answer got lost. But there should be no real difference sonically between an H-frame and a W-frame dipole sub.
The W-frame is more compact, and vibrates less. Audible? Who knows.
If you lay the H-frame on it's side, you may get louder bass because of floor reinforcement.
Mine are upright for aesthetics.
Cheers
Steve
The W-frame is more compact, and vibrates less. Audible? Who knows.
If you lay the H-frame on it's side, you may get louder bass because of floor reinforcement.
Mine are upright for aesthetics.
Cheers
Steve
H-frame versus W-frame
The difficulty of construction I can understand... even SL mentions the assembly problems. Repairs will be even trickier, I presume. What is this "one-piece design" that you mention? Do you mean that you wanted both speakers on one plank of wood? You probably meant something else...
Tarun
sfdoddsy said:
The difficulty of construction I can understand... even SL mentions the assembly problems. Repairs will be even trickier, I presume. What is this "one-piece design" that you mention? Do you mean that you wanted both speakers on one plank of wood? You probably meant something else...
Tarun
Cap values for tweeter XO
As inspiration, I have Lynn Olson's account of tuning the Ariel crossover: 15 months.
If you're using 1.5uF with an 8ohm tweeter, does this mean your XO is > 10KHz?
Thanks for the patience and information, all of you.
Tarun
Thanks. I can then stock up on some ones, twos, and threes (in uF, I mean) of metallised polyster and combine them for my experimenting. I just re-read Lynn Olson's Ariel pages, and he seems to believe metallised polyster is junk (maybe they are), but then I'm using five-dollar drivers for prototyping.navin said:
Do you wind your own coils? I guess you'll have some simple formulae for winding air-core coils using thick copper wire? Can one use a piece of aluminium pipe for mechanical support as a "core" without affecting the impedance of the coil? Just curious.... I can always use a cardboard core.
Thanks for the tip. Will remember. However, I'm probably going to opt for active LR XO (2nd or 4th order) if the simple first-order tweeter cap doesn't work out. I'll keep you posted.
I'll remember this. I agree that DIY seems to need patience. Whenever I've forgotten this, I've screwed up.
As inspiration, I have Lynn Olson's account of tuning the Ariel crossover: 15 months.Thanks for the pointer. I now know the range of values I need: 1-10uF. But you're right about the "right" value changing depending on whether I use plain mid-drivers or FR drivers. For the Jordan, I guess my experience will be similar to yours. But for the prototype I'm planning with the USD 5.00 Philips India 8" FR driver, I don't know. Maybe it rolls off so early that I'll need to bring in a tweeter quite early, in which case a 6dB slope might not be safe for the tweeter. I read Lynn Olson's Ariel design story where he talks of how a first-order slope is not suitable for a tweeter unless the XO freq is set waay high... this is because the excursion increases at the rate of 12dB/oct as you move down the frequency spectrum, which is not sufficiently compensated by the 6dB/oct rolloff, thus leading to the tweeter bottoming out and sounding harsh. Very fundamental, I thought. Therefore, unless I can set the XO frequency at something like 6KHz, I may encounter similar problems, which will make me switch to second-order slopes, at which time... I'll switch to active line-level XO? God knows.Variac said:
If you're using 1.5uF with an 8ohm tweeter, does this mean your XO is > 10KHz?
Thanks for the patience and information, all of you.
Tarun
consider the bob 3 on steve's site. how deep is the bass box?
steve can you help here? my object is to build a dipole that is very WAF friendly. hence i am looking at side mounted bass drivers that will operate below 100Hz. coupled to either an open back mid (with side walls to lower the F3 of the mid) or a push push TL for the mid.
the drivers i am looking at are:
2 x 12" for the bass in a box that is 30"Hx16"D x 12" W
2 x 6" for the mid and a 1" for the HF
steve can you help here? my object is to build a dipole that is very WAF friendly. hence i am looking at side mounted bass drivers that will operate below 100Hz. coupled to either an open back mid (with side walls to lower the F3 of the mid) or a push push TL for the mid.
the drivers i am looking at are:
2 x 12" for the bass in a box that is 30"Hx16"D x 12" W
2 x 6" for the mid and a 1" for the HF
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