About to try and build a great 2way floorstander.

[Bredin]

forget this post. The thread starts after some posts

[joecarrow]

I've said it before, and I'll say it again- transmission lines are far more useful for managing "inside the box" acoustics- for example, eliminating standing waves and stored energy inside a midwoofer's pass band- than they are for performing bass miracles. You can do a bit better with a transmission line than a sealed box, but not terribly better.

You'd be surprised how good a *properly tuned* bass reflex can sound. Go have a look at some of the top brands- they're almost all using bass reflex- even B&W. Yes, B&W's flagship speaker is all transmission-line based, but they are closed transmission lines with no porting to the room. The tapered tubes used in the B&W nautilus effectively (or I suppose they do this effectively- I haven't heard or measured one myself) absorb and dissipate the rear waves of all drivers.

If you're concerned that crossing a tweeter too low is going compress things, have some consideration for a waveguide. There's a darned good reason that people around here are pushing crossover points so low. The primary reason is that the woofers' linear distortion almost always picks up and becomes a problem by 2khz. A secondary reason is that if you run a woofer too high, the woofer starts to beam and the discontinuity between woofer and tweeter directivity is a big problem. I made this mistake on my first design, and after I heard it, it stuck out like a sore thumb.

You're looking at investing in some really pricey drivers. I have to say, my recommendation to you is to reconsider unless you're willing and able to do your own measurements, and are planning on designing a crossover based on those measurements. I had no idea how critical a properly designed crossover is for the overall sound, but after I built the Modula MT I was converted.

I wish you luck, and hope my response was of some help.

[Bredin]

I've said it before, and I'll say it again- transmission lines are far more useful for managing "inside the box" acoustics- for example, eliminating standing waves and stored energy inside a midwoofer's pass band- than they are for performing bass miracles. You can do a bit better with a transmission line than a sealed box, but not terribly better.

You'd be surprised how good a *properly tuned* bass reflex can sound. Go have a look at some of the top brands- they're almost all using bass reflex- even B&W. Yes, B&W's flagship speaker is all transmission-line based, but they are closed transmission lines with no porting to the room. The tapered tubes used in the B&W nautilus effectively (or I suppose they do this effectively- I haven't heard or measured one myself) absorb and dissipate the rear waves of all drivers.

If you're concerned that crossing a tweeter too low is going compress things, have some consideration for a waveguide. There's a darned good reason that people around here are pushing crossover points so low. The primary reason is that the woofers' linear distortion almost always picks up and becomes a problem by 2khz. A secondary reason is that if you run a woofer too high, the woofer starts to beam and the discontinuity between woofer and tweeter directivity is a big problem. I made this mistake on my first design, and after I heard it, it stuck out like a sore thumb.

You're looking at investing in some really pricey drivers. I have to say, my recommendation to you is to reconsider unless you're willing and able to do your own measurements, and are planning on designing a crossover based on those measurements. I had no idea how critical a properly designed crossover is for the overall sound, but after I built the Modula MT I was converted.

I wish you luck, and hope my response was of some help.

I have a pair of B&W 705 atm. And they preform a great bass and i my ears a very good midrange with a XO point of 3700Hz.

Nothing that is DIY is final, it's just at test. If the filter sounds bad, I just make another one, or if I have problems with the T-line, i's just to build a sealed or bassreflex.
The thing with me wanting a T-line is to not stress the driver to hard.

Well. Let's see how it goes

[Bredin]

bVfObafSS.gif Image not available

can something like this work? A thinner baffel for less turbulence and than thicker walls and then a real thick one in the middle?

[ThomasW]

If yours are anything like these, they really a midrange and shouldn't be expected to run low...

https://web.archive.org/web/20080304190747/http://www.gattiweb.com/delta_design

Some discussion regarding the driver

https://www.htguide.com/forum/showthread.php?t=13000

[Bredin]

If yours are anything like these, they really a midrange and shouldn't be expected to run low...

https://web.archive.org/web/20080304190747/http://www.gattiweb.com/delta_design

Some discussion regarding the driver

https://www.htguide.com/forum/showthread.php?t=13000

Mine are custom with a higher qts. According to ATs simulator,with my specs they should hit 48hz-3dB in a 15litre bass reflex box or 84,5hz in a 11litre closed enclosure.

And I'm not expecting earth quacking bass either. my room is only 11,5m^2 and my B&W are a little bit to big for the room. So I think that the cq15 will do the job.

The drivers are ordered by the way. So don't complain, so I don't have to regret what I've done :T

[ThomasW]

No complaints on my part....

Your .....

I made some simulations with a 45litre basreflex box and with a vent tune down to high 20's, I'd hit about 26Hz -6dB

statement is what's problematic, since the drivers are midranges not midwoofers.

[TacoD]

I used the 15H in serveral setups, and it's a bit small to get low extension. Most of the time I use the 15H as extended mid (x-over <= 150Hz - 200Hz). The 6600 is a very good match for the 15H, I got good results. The nice thing of the 15H woofers is the low Q, but obviously you do not agree. To make things clear I got great results with closed and basreflex application.

As far as I can conclude from your opening post you are not that experienced so please do not state that some applications are not right.

[Bredin]

I used the 15H in serveral setups, and it's a bit small to get low extension. Most of the time I use the 15H as extended mid (x-over <= 150Hz - 200Hz). The 6600 is a very good match for the 15H, I got good results. The nice thing of the 15H woofers is the low Q, but obviously you do not agree. To make things clear I got great results with closed and basreflex application.

As far as I can conclude from your opening post you are not that experienced so please do not state that some applications are not right.

I wanted a higher Q becuse I've heard that atleast 0,4QTS i recommended for a T-line box.
The driver is still a pretty fast one with about 600accelerationfactor. And 88dB/spl.

Can't wait till I get the drivers so I can order about 10different filters and test low VS high XO point

[TacoD]

Success! I think you will like the quality of these drivers. But plz do yourself a favor do not push these to the limit .

[MarcE]

I am using the 15H as well. I found the ferro-fluid Peerless HDS 810921 to be a great match. I was planning on trying the 6600 at some point, but now I've stopped thinking about it and am just working on getting the HDS to sound good. I also played around with the Vifa XT25 as well. Here's a good comparison between the three:

http://www.customanalogue.com/elsinore/elsinore_15.htm

[Bredin]

That seems to be a great match. I thought about the HDS tweeter, but it just felt to cheap ><. High price = placeboeffect . Guess that I'm retarded in some way

I will start a new building thread with measurements and pictures and other stuffs when I get the drivers

[Bredin]

Look what I've got

[MarcE]

nice! looks very familiar! For everyone following along, here's a picture of the rear (of mine).

As for the HDS tweeter feeling cheap, no need to be ashamed of spending more on the crossover parts that the tweeter itself! That way you can still get your placebo effect!

[Bredin]

It's impossible to understand how brutal the driver looks IRL on pictures!
Can't wait to crossover testing and box building. But I have some things to do first. I Have a project in school to build a prototype of the final speaker, and I have to write diaries ,time plans :x , mentor meetings :M and write a rapport :evil:

Okay, I've partly finished the design of the speakers.

Image not available

(Picture may seem dark on some screens)
This kind of finish:

Image not available

(I think that it looks great and serious, serious because you make a loudspeaker to look like a loudspeaker, not a piece of furniture :rofl: )
The 5" port at the bottom is the port for the line, think it looks cool with a port that is the same size as the driver instead of some boring slit.

The biggest problem right now is what kind of material to use for the box and how the XO will look.
Any good suggestions on good materials? I prefer to make the baffle and the line in stiffest possible wood, and maybe the sidewalls in MDF or so. I've bought loads of 4mm think lead math to damp the high box resonance with+ that the bok will be filled with damping. So stiff wood plox!

And about the XO. I'm thinking of a 12db/octave@2500Hz+notch for the bass driver. But I don't know how really, haven't found any good calculators yet. And I'm not thinking of making just one filter and be settled with that! I want to make many different filters and try what fits me best.

My CQ15 data:
SD:92cm2
Vas:20,58L
Cms:160e-03 m/N
Cas 1.47e-07 m^5/N
mmd: 7,95g
mms: 8,48g
Rms: 0.77Ns/m
FS: 43,3Hz
BL: 5,15
Re: 5,30ohm
Le:0,00mH
Qms: 2.98
Qes: 0,46
Qts: 0,40
The impedance is 8ohm@2kHz, 6ohm@200Hz(lowest) and 9ohm@5kHz. So the impedance is a very slow tilting curve.
(frequency response looks like the normal CQ15, but with 0,5dB lower)

the d3004/660000 data adn curves
Any suggestions?

[Bredin]

bump@edit

[TacoD]

Like I said before, I've some experience with the 15/ 6600. I tried several combinations:

- cross < 2500 Hz if you want a dynamic and precise stereo image (use a series coil with a LCR). The 6600 can easily take a x-over point of 2000 Hz.
- If you cross > 3000 then the sound becomes a tat warmer (Very Audio does that), the 15H has to work harder, and is not as clean as a tweeter @ 3500 Hz but you get a more involving sound (distortion?). I think this will match your TL tuning very nicely.

The pictures show an underhung motor, what voice coil former did you choose? Hopefully you picked an aluminum former, otherwise you do not get very tight bass.

Good luck

[Bredin]

I actually don't know :|. The driver should be stock, but with a higher QTS. I don't think that I will be unsatisfied with the bass if it's with kapton coil. You can always compensate the bass by adding a subwoofer + active crossover, but the midrange..
The spec paper that came with the driver said that it was a bass driver. So maybe it's alu. But by puing the in the cone, comparing with my B&W 705, I can feel that there is way less resistance in the AT driver. Hopefully the transmission line+room will compensate for the bass anyhow.
My 705s are crossed at 3700@12dB and sounds great in the midrange. So I'm not skeptical of a >3500 XO point.
Well, can't hopefully be worse than if I've to buy a new set of CQ15s
The coil is silver.. if that says something :T



Aluminum VoiceCoil



kapton VoiceCoil
Source complains over the alu and kapton VCs.

[rc white]

The points made about transmission lines are true, I have demonstrated many times that anything a given driver can do in a transmission line it can do better in a reflex box.
At Rod Elliots ESP website I have published two articles, the first "Satellites and subs", describes QB5II filter assisted reflex alignments which optimize the coupling between resonator and driver and greatly increase the power handling of small drivers.

http://sound.westhost.com/qb5align.htm

In the second "Compliance scaling" I present a method of getting an exact target f3 with a particular driver.

http://sound.westhost.com/articles/cscaling.htm

With these it is easy to get 15db. more excursion limited power handling than a t line, and if you are going to use all the space to the floor anyway I would have thought a 2.5 way would be called for, with the techniques I described you can easily get a usable 40Hz. f3 with two six inch drivers.
rcw

[JonP]

Image not available

can something like this work? A thinner baffel for less turbulence and than thicker walls and then a real thick one in the middle?

Not sure what you mean by less turbulence with a thinner panel, unless you mean the thickness would mask the backwave of the driver. Then, chamforing the backside with a 45 deg router bit will help.

Usually, you want to make the front baffle thicker, to better make a solid non-vibrating slab for the drivers. The sides, back and divider should be as thick as needed to be for a solid, well dampened box.

[Bredin]

Not sure what you mean by less turbulence with a thinner panel, unless you mean the thickness would mask the backwave of the driver. Then, chamforing the backside with a 45 deg router bit will help.

Usually, you want to make the front baffle thicker, to better make a solid non-vibrating slab for the drivers. The sides, back and divider should be as thick as needed to be for a solid, well dampened box.

Can say that that design is out of the question now.


that kind of line is more "effective" in my short design.
Thinking of making the baffle 4cm and the rest of the box 2cm.

I've heard that Baltic birch plywood is pretty stiff.

[tf1216]

I wish I saw this thread sooner. I have a 2-way design at home with the !8H and the 6600 tweeter. My 18H is the pretty much the equivalent to a standard 15H driver with the underhung motor and similar kapton former. Mine is the one tested on Zaph's website. As you could figure, the bass is not prominent but it was meant to be played with a woofer and be played LOUD.

Keep plugging away, you will love the speaker when you are finished.

[Bredin]

ATM, the drivers are parallel wired to my amp, and playing some music at low a low level. just to burn them in abit.

How reliable are these calculators?
And what do you think is the best way go get rid of the peak in the CQ 15?

[Dennis H]

How reliable are these calculators?

Such "textbook" calculators are nearly worthless. For the cost of one of your woofers you can buy LspCAD and a measurement mic. If that is too much, Speaker Workshop is a free download. Either one will let you take real measurements and model the real response of the speaker.

[TacoD]

....
The coil is silver.. if that says something :T

The stock driver has an aluminum former, and if it looks "silver" at the point it attaches the cone, then it's a metal former. The suspension is very light, that's the reason you need some kind of "electrical" brake, which is the case with the aluminum voice coil former.

You need a notch filter for the peak in the AT. As I described in an earlier post, a series coil with a rightly tuned notch will do the trick. I cannot give you some values, because I never used the version you got. So you need to do some measurements.

[Bredin]

The stock driver has an aluminum former, and if it looks "silver" at the point it attaches the cone, then it's a metal former. The suspension is very light, that's the reason you need some kind of "electrical" brake, which is the case with the aluminum voice coil former.

You need a notch filter for the peak in the AT. As I described in an earlier post, a series coil with a rightly tuned notch will do the trick. I cannot give you some values, because I never used the version you got. So you need to do some measurements.

What kind of measurements?

And for box material. I think I'll begin with simple MDF and test it.
Everything in the design is clear but one part! How does the area of the line effect the sound? I've asked that question at 3 forums without any answear.

[rc white]

the tl

The major fact about the transmission line is that it is a resonant pipe that has resonances when one end reaches an impedance maximum, and the other a minimum.
You only want the quarter wave resonance to radiate so you stuff the line to absorb all the other resonances.
In practice what you end up with is a harmonic series of more or less damped low q resonances that research shows are very audible.
Putting a port in the bottom turns the overall enclosure into something that can be best modeled as a badly designed reflex box with heavy damping in its port, with the addition of a low q harmonic resonant series as output.

Added to all this is the fact that the excursion limited power handling of this is barely more than that of a a fully sealed box and given the driver size it will only have useful non excursion limited bass down to 80-100Hz. and be grosely overloaded at lower frequencies.
In short you want a good two way floor stander, and the one you seem intent on isn't one.
rcw

[Bredin]

The major fact about the transmission line is that it is a resonant pipe that has resonances when one end reaches an impedance maximum, and the other a minimum.
You only want the quarter wave resonance to radiate so you stuff the line to absorb all the other resonances.
In practice what you end up with is a harmonic series of more or less damped low q resonances that research shows are very audible.
Putting a port in the bottom turns the overall enclosure into something that can be best modeled as a badly designed reflex box with heavy damping in its port, with the addition of a low q harmonic resonant series as output.

Added to all this is the fact that the excursion limited power handling of this is barely more than that of a a fully sealed box and given the driver size it will only have useful non excursion limited bass down to 80-100Hz. and be grosely overloaded at lower frequencies.
In short you want a good two way floor stander, and the one you seem intent on isn't one.
rcw

I've seen some T-lines with small drivers. And the port on my design is only a port, not a tube. Just as a replacement of the normal quadratic slit.
I've found ports with the same area as my driver, and they only costs like 7$ 8)

[TacoD]

What kind of measurements?

And for box material. I think I'll begin with simple MDF and test it.
Everything in the design is clear but one part! How does the area of the line effect the sound? I've asked that question at 3 forums without any answear.

You need to measure the actual frequency response, so you know exactly the frequency of the peak in the response. In combination with information of actual impedance measurement you can calculate the the right correction network.

The tapered line 'loads' the loudspeaker, a different area will result in a different resistance to the woofer. How this exactly translates to sound, I do not know. The line primarily affects the low frequency response. As with all things in loudspeaker construction you need to find a balance between tuning, crossover, cabinet which works out for you. As you already found out it is not as easy as it looks .

[rc white]

excursion limiting

No matter what the actual physical arrangement of a tl the model remains the same.
Many years ago Small came up with the power handling constant 'kp', this is related to other parameters by.

w = kp*f3^4*vd^2

w= acoustic power in Watts, vd=volume displacement of driver in m^3, f3=desired lower cut off.

The value of kp varies from .85 for a sealed box, 1-1.2 for a tl, and a typical reflex comes in at 3, filter assisted reflexes vary between 6 and 70.

If you put a few numbers into this using the manufacturers rated linear cone excursion as I mentioned before you will find that drivers of the size of yours start running out of linear excursion before they are producing usable sound levels unless f3 is restricted to 80-100Hz. for sealed boxes and transmission lines, reflex boxes having 6db. more excursion limited output, some filter assisted alignments can have as much as 18db. more.
This is the unfortunate physics of the situation and despite inferences to the contrary tl cannot by some cunning means get around it.
rcw

[Bredin]

No matter what the actual physical arrangement of a tl the model remains the same.
Many years ago Small came up with the power handling constant 'kp', this is related to other parameters by.

w = kp*f3^4*vd^2

w= acoustic power in Watts, vd=volume displacement of driver in m^3, f3=desired lower cut off.

The value of kp varies from .85 for a sealed box, 1-1.2 for a tl, and a typical reflex comes in at 3, filter assisted reflexes vary between 6 and 70.

If you put a few numbers into this using the manufacturers rated linear cone excursion as I mentioned before you will find that drivers of the size of yours start running out of linear excursion before they are producing usable sound levels unless f3 is restricted to 80-100Hz. for sealed boxes and transmission lines, reflex boxes having 6db. more excursion limited output, some filter assisted alignments can have as much as 18db. more.
This is the unfortunate physics of the situation and despite inferences to the contrary tl cannot by some cunning means get around it.
rcw

So you think that I should go for a sealed box instead?

And I don't play as loud as you other guys.. My room is 10,5m^2 and I'm sitting 2,3meters away from the speakers. And I never play louder than 98dB.
Don't know how loud I usually play, but not over 98dB. that's for sure

[TacoD]

For such a small room a closed box is ideal.

[rc white]

If for instance you use the largest 'air suspension' box, vas/3, the driver is -3db. at around 60Hz. and to play at a peak of 98db. needs getting on for 7mm. peak excursion, this drops to 1.9mm. for a typical reflex box.

As you live in Sweden I imagine your room is well sealed and will give useful room gain, but even so you are driving the woofer very hard, (you do not specify peak linear excursion, but I imagine it is less or at maximum 7mm.), and that is not good for overall quality.
rcw

[Bredin]

If for instance you use the largest 'air suspension' box, vas/3, the driver is -3db. at around 60Hz. and to play at a peak of 98db. needs getting on for 7mm. peak excursion, this drops to 1.9mm. for a typical reflex box.

As you live in Sweden I imagine your room is well sealed and will give useful room gain, but even so you are driving the woofer very hard, (you do not specify peak linear excursion, but I imagine it is less or at maximum 7mm.), and that is not good for overall quality.
rcw

So you think that I should go for a basreflex solution rather than a transmissionline?
And what resonance frequency of the tube and how large should the box be?

After reading some articles, like Huble Homemade HIFI's optimo or the swedish DR.krupps transmissionline princip description , atleast I can't find anything that says that BR is better than TL.
But today I saw This article. I'ven't read it yet, just looked at some frequency comparisions between all the different box types, and the TL response wasn't all to pretty ops: . Humble homemade Hifi's TL measured better than the BR he tested, and in the report/article the BR seems to measure alot better. I'm confused :x

[TacoD]

Stick to the plan I would say. Your driver should work for in a TL enclosure. A bassreflex enclosure is more efficient and measures better. But you can always try that after your TL endeavor.

[Bredin]

Well.. This thread is about me trying to build a great loudspeaker. And if a BR solution is better, it's more ontopic . And a BR solution gives more freedom in the box design part.
Maybe a Sonus faber Amati design with Magico Mini box solution. Would look way better than the TL i thought of, that's for sure

[rc white]

This driver has T-S parameters that make it fit an almost exact B4 alignment, at 20 liter box tuned to 43 Hz. it has an f3 around 42Hz.
Personally I would use two of them in a 2.5 way configuration in a 40liter tower for a floor stander, the low cone excursion gives very low modulation and odd order harmonic distortion in the upper bass and midrange, always a problem with a small cone used over such a wide bandwidth.
The consequence of this, if done properly, is that elusive "effortless" and "clean open" quality.
rcw

[Bredin]

This driver has T-S parameters that make it fit an almost exact B4 alignment, at 20 liter box tuned to 43 Hz. it has an f3 around 42Hz.
Personally I would use two of them in a 2.5 way configuration in a 40liter tower for a floor stander, the low cone excursion gives very low modulation and odd order harmonic distortion in the upper bass and midrange, always a problem with a small cone used over such a wide bandwidth.
The consequence of this, if done properly, is that elusive "effortless" and "clean open" quality.
rcw

I would use 4 of these drivers in my project, if they didn't cost so damn much . Well, lets finnish this project, then later I might throw some more money into the pit :Z

And woulden't it be the same if I added a subwoofer later? I've heard subwoofer making a great difference in clarity to normal speakers.

[TacoD]

Well.. This thread is about me trying to build a great loudspeaker. And if a BR solution is better, it's more ontopic . And a BR solution gives more freedom in the box design part.
Maybe a Sonus faber Amati design with Magico Mini box solution. Would look way better than the TL i thought of, that's for sure

:T Why do you buy woofers before you do more research (e.g. a standard C-quenze is optimized for BR). Your woofer will also work, but maybe it is better performing in TL.

[Bredin]

:T Why do you buy woofers before you do more research (e.g. a standard C-quenze is optimized for BR). Your woofer will also work, but maybe it is better performing in TL.

Becuse the reseach I did before I bought the AT drivers said that TL was superior to BR. And becuse this is actually a school project, I need to keep atleast some deadlines. And CQ15 with 0,4 QTS seemd to work well in TL,BR and seald enclosures and still give some kind of deep bas. I picked the 0,4 qts cq 15 over the cq18 becuse the CQ15 still has a higher acceleration factor, and is physically smaller. I'm looking for the same thing as almost everybody else, a small speaker with deep bass . But now in secound hand, I'm almost starting to doubt my 0,4 was for any improvment at all.

[rc white]

If its for a school project all you need to do is to point out what I posted about Smalls power handling coefficient and the reason why bass reflex is to be preferred and the amount of total crap you find on the net about the magical properties of transmission lines.

As I and others have pointed out a transmission line is basically a complicated way of making an overlarge bad reflex, and if you want the deepest bass from the smallest driver filter assisted reflex boxes win every time, this is not opinion but demonstrable fact.
rcw

[Bredin]

If its for a school project all you need to do is to point out what I posted about Smalls power handling coefficient and the reason why bass reflex is to be preferred and the amount of total crap you find on the net about the magical properties of transmission lines.

As I and others have pointed out a transmission line is basically a complicated way of making an overlarge bad reflex, and if you want the deepest bass from the smallest driver filter assisted reflex boxes win every time, this is not opinion but demonstrable fact.
rcw

About the filter assisted reflex box, it's simply just a box tuned to the wanted resoance than the filter is used to cut of the lower frequencies from the driver. Am I right?

I think that my B&W 705 delivers deep bass without to much cone movement, and the filter is only 2coils, 2capacitators and 2resistors, and it seems to work fine for me.

And about building a 2.5way speaker, and if a subwoofer will give about the same effect, is there any answears to that? Seems pretty much the same to me, as long as the 2drivers are in seperate boxes.

[EdL]

I believe you would be well served to check out Martin King's website:

http://www.quarter-wave.com/

There's more there than can be summarized in a few sentences. I think it is the best source for the science behind the idea.

I've completed the Modula MTM as a MLQW and am very happy with it. The fact that it is -3dB @ 30 Hz (in room) doesn't bother me a bit. It is excursion limited. I don't have the need for sound that low to play much above 105 dB

[Bredin]

I believe you would be well served to check out Martin King's website:

http://www.quarter-wave.com/

There's more there than can be summarized in a few sentences. I think it is the best source for the science behind the idea.

I've completed the Modula MTM as a MLQW and am very happy with it. The fact that it is -3dB @ 30 Hz (in room) doesn't bother me a bit. It is excursion limited. I don't have the need for sound that low to play much above 105 dB

The more I can avoid excurison the better it is, and if a subwoofer does the same to the harmonic distortion, there's no need for my speaker to go very deep. If so, the best alternative that I can see is if I could send them back to Skaaning and have the driver fixed with a <0.35 qts, and maybe some other customisation I never thought of before.

I was only into transmissionline becuse of all the things I read said that it was so good, and deliverd deeper and faster bass than BR and had the same or better impuls response than a seald enclosure, and that it hade lower distortion and stressed the driver less. But now when I know that that isn't the case, my driver is starting to feel missfit, and that I seriously could consider recalibrate it, if it is possible. So. Would you have done any more changes to my driver more than the QTS? In wich case, what and why?
The normal CQ 15 has a qts of 0,33. So incase that a subwoofer works the way I want it to, it's maybe an idea to lower the QTS even lower? Like 0.28 QTS? @120W the driver would not reach its excurison limit above 50Hz, but with my driver, it hits the roof above 100Hz, and I guess that that could be pretty bad for the midrange :rofl:

[rc white]

This is an article I wrote regarding the application of filter assisted reflex alignments to satellites.

http://sound.westhost.com/qb5align.htm

This is a satellite I have made along these lines.

http://sound.westhost.com/articles/ssl1.htm

The filter assisted alignments differ according to group, group I give the best extension for box size and the filter is around q=2, i.e. 6db. boost, the group II optimize the coupling between the Helmholtz resonator and the driver, this greatly increases the excursion limited power handling and these alignments are very useful for small satellites.

In the quarter wave link note that King himself says that the transmission line acts as a pseudo reflex, I would add it is a complicated overlarge and poorly performing one.
rcw