The making of: The Two Towers (a 25 driver Full Range line array)

Not if one wants a smooth bass line over a large wide area. Then distributed bass just works wonders :). Part of that distributed bass concept are the arrays, that do things that the subs can't. Because there are many of the little drivers, all positioned slightly different. Averaging is the key here.

Sorry, the concept here isn't new (to me). 5 dB of boost is nothing, when one distributes it over 25 drivers. And that's the maximum boost number.
I have 2 subs, there aren't any more coming (let's just say: simply not allowed). 2 Subs cannot do as well as 2 subs helped out by 2 arrays that get support from the room. It's as simple as that. It might not be conventional, but nothing I do really is. :D But I didn't grab it out of thin air or braking any rules either. Except for some old wisdom perhaps, that stems from a different kind of thinking. What I do and how I do it has been a lot of work, most of it detailed in this thread. I've always used the arrays below their Fs, and even made sure to let them share that load evenly when there weren't any subs to help out. Making sure they weren't overused.

Don't worry though, no 10F's are going to be tortured if they cannot take it. No TC9's ever were...

Bottom line: if the arrays weren't as close to a wall as they are, yes... you'd be right. But they are and that helps them play low and pretty clean. The room size matters too. We will see if the 10F can do the same, the TC9's never had a problem with it. That may be hard to believe, but if they could stand 14 dB of maximum boost (*)
for 5 years, the 5 dB of boost, left after adding the subs was peanuts. The 10F's are 3 dB more sensitive in the bass notes. I expect them to be able to match
the TC9's. If they fall short, I will adapt. No one figured the TC9's could ever produce useful bass.

Recommended or not, it just works. Due to the large number of drivers, their specific position and the averaging of reflections. End result is way smoother results than any of them by themselves. Which really works well over a large area.

Did I try a simple crossover? Yes. Was it better? Most certainly not. Sorry... but this is rather old news after playing with these things for years. I know what the can do and what they can't do. There isn't much I did not try.

P.S. for fun try looking up where I announced I wanted to add subs to my arrays. There were a few members here that had heard my arrays in my home that did not feel I needed to add subs. And for music I really did not need them. These things can do way better than many would ever think they could. When used properly.

I have proof that the TC9's that broke down all suffered the same faith: failure of the lead wire to voice coil connection. Right under the dome. I checked all but one.
A failed solder connection. So no driver ever failed due to overuse or too much power put trough them.


(*)= at peak efficiency for the array's around 200-250 Hz, there is a 10 dB cut
 
Last edited:
One more note: the true benefit of adding subs was for movies. But it has been documented here, complete with measurements...

For music? I did not experience a vast improvement after adding the subs and relieving the arrays from sub duty. Having them share the load with the subs did have some advantages as there were more options to share the load, to create more even bass (over a wide listening area). Using each of the "player's" strong points.
 
it's not being conventional (or not) and all (don't really care about that part).

But I am just looking at the distortion curves as well as maxSPL, plus that issue with Cms (which is real)
Even with so many you just touch around 100dB at 40Hz maxSPL.
Nothing to be super proud of. But true, in the corner it does give some extra boost.

An 8 or 10 inch in on the bottom of the array (so two in total left and right) will easily blow these numbers away.
Purely talking about just musical performance, not about breaking things.
With this construction EQ'ing and delaying the low-end to get rid of those pesky standing waves is also more difficult.

I was just mentioning it, if you're totally happy with it, no worries and happy days! (y) :cool:
 
b_force,

are you looking at the TC9 graphs from the company or from wesayso's shared data?
If you are looking at company's graphs, I suggest you look at the post counter of this thread.

that's over 7,000 posts, in a span of 9 years.
Maybe, just maybe, there is some info in there regarding your concerns.
The owner has been over that a few times already.
Dropping in at post 7000-something and saying, "I think you are doing it wrong," is kinda low respect, especially since wesayso has been testing his theories and sharing his data for everyone to see in the last 9 years.

You just can't look at the graphs from one driver, and think that 50 of them, working in unison, will be exactly the same.
Those 50 3.5" drivers will blow your dual 10" at the bottom of the arrays, anytime. Don't believe me, just look at the data shared in this thread.
 
Last edited:
@perceval
ehm I have over 10-15 years of professional experience, don't need 7000 posts to know what I am looking for?

Again, it was just a thought, I also never said that anyone did anything "wrong" (in fact, quite the opposite!!)

Respect goes both ways, but I know @wesayso long enough that we both know that.
There is also nothing wrong looking at something again from a fresh set of eyes.
In fact I would highly recommend doing that, even to ones own work.
 
Congrats on being an expert.

You did say that a single 10" at the bottom of the line would be much better, so in a sense, telling that using only the TC9 is wrong, but didn't post anything to support your theory.
And you still didn't mention which data you are looking at to base your own theory.

As I said, it's been discussed over here. It's nothing "new" to this thread.
Thinking that in 7,000+ posts, you'd suddenly come up with this "fresh approach" is funny. :)
 
Congrats on being an expert.

You did say that a single 10" at the bottom of the line would be much better, so in a sense, telling that using only the TC9 is wrong, but didn't post anything to support your theory.
And you still didn't mention which data you are looking at to base your own theory.

As I said, it's been discussed over here. It's nothing "new" to this thread.
Thinking that in 7,000+ posts, you'd suddenly come up with this "fresh approach" is funny. :)
If the approach is a bit more friendly and constructive, I am more than happy to explain things.

In a sense I absolutely did not say something is wrong.
It's also not just an theory.
 
You're right. At this point, we've past the point of "theory."

But yes, by all means, if you do know much better than all the great minds (don't worry, I'm not including myself here) that passed through this thread already, then please, explain yourself.

I'm not being "unfriendly", you, yourself, just said that we should keep our eyes opened. So, you do understand that I could question what you are saying as well?

So, kindly explain why you think your approach is better, supported by data, and we can all have a more meaningful conversation.
Cheers!
 
An 8 or 10 inch in on the bottom of the array (so two in total left and right) will easily blow these numbers away.
Purely talking about just musical performance, not about breaking things.
With this construction EQ'ing and delaying the low-end to get rid of those pesky standing waves is also more difficult.
A 25 driver TC9 array has a Vd of about 230cm3 each, this falls in between an average 8" or 10" woofer. It is sufficient for normal home music levels when EQ'd but certainly it is no SPL monster. The array runs out of volume potential at the top just as it does at the bottom so adding woofers does not remove that restriction.

These arrays really do produce great sounding in room bass. I bought 2 Dayton RSS390 15" sub drivers, they have never left their boxes, they will eventually but nothing about the sound of the bass I already get makes me in any hurry.

The comparison between an outdoor measurement and an in room measurement I did was quite surprising to me. Apart from some boundary gain and a few dips and bumps they were very similar. More similar than most conventional speakers manage.

Sometimes things work better than the numbers would suggest, for me this is one of those times.
 
@perceval
ehm I have over 10-15 years of professional experience, don't need 7000 posts to know what I am looking for?

Again, it was just a thought, I also never said that anyone did anything "wrong" (in fact, quite the opposite!!)

Respect goes both ways, but I know @wesayso long enough that we both know that.
There is also nothing wrong looking at something again from a fresh set of eyes.
In fact I would highly recommend doing that, even to ones own work.
Don't worry. Everything I have done or tried I've done or tried at least twice. I'm still an engineer at heart. :)
Usually I only change one thing at a time. Adding the filters and remodeling my home was one of the first times I deviated from that.
I get why perceval reacts the way he does, as we have been over this same routine more than once in this thread.
I get it that there are people that want PA levels. I want a reasonable level that I can sustain for hours on end without damage.
-- looking for an average of 85 to 87 dB, see further up --

I have tried the conventional crossover (at least twice). But one sub in one spot reacts to a room in a certain way. It won't have a flawless output at the listening spot plus it's direct environment. 2 Subs do better, if we use the strong points of both subs we can get some averaging going to smooth out the response.
Adding the 2 arrays goes one step further. But I only use them where they do get extra help from their specific spot inside the room. Lots of work, yes. But after all those years I do know what it can and can't do. Where they make the easy SPL levels.

100 dB at 40 Hz is the start, of 25 drivers added in a simple calculator. It isn't factoring in the corner placement and the fact that we've spread the source over a long thin line. So what we get at the listening position is more than that of a 10" woofer of similar size. As it is acting as a distributed source plus being a line source. So over a distance I get to keep more of that SPL level than I do of the single woofer, and a lot smoother output with less dips and/or peaks.

Sd = 36,3 cm2, 25x 36,3 = 907 cm2, but... only usable over 2.55mm x-max. X-mech will be 7 mm, but we need to obey the safety of x-max.
As fluid said, depending on the woofer we're in the 8 to 10" category, depending on their x-max. But one 8 or 10" isn't a line source.
Even though the line is too short below 100 Hz to really look at it that way, when the floor and ceiling mirror's are factored in it still behaves as a line,
as in the drop per doubling distance isn't far from the known 3 dB figure. So we make SPL but get to keep more.

I'm looking for average playback of 85 to 87 dB. A Radioshack SPL meter never is far from the listening position. On top of that I'd like to sustain the dynamic range of music. We have 2 speakers and due to pretty much excellent summing I can get pretty close to my goal inside my room.
I think I have found 3 tracks I could not play at the mentioned average level. (JRiver is making sure each song is being played at similar SPL levels, despite it's dynamic range) 2 of them I forgot about (lack of interest), they may be in this thread somewhere. The one I do remember is a lullaby. to be more exact: "A Perfect Circle - Lullaby"
The pumping bass on that song is marvelous. I think most users have never heard that song in full, with speakers that have 'output' down to ~20 Hz.
I had to bypass JRiver's level feature for that song and adjust volume by hand. JRiver wants the whisper voice to be 85 dB on average. That will make the bass line go
above what I could handle. Dropping it about 5 dB I could still play the song. By memory the peak of the pumping bass is at ~25 Hz. With the Arrays sans sub, I used to add a (safety) first order crossover for movies.

Most songs I play fall between a 12 to 15 dB of dynamic range. I have some silly new stuff that has 6-7 dB of dynamic range as well, just to try it. But hardly any song really has the 20 dB of dynamic range that I want to keep for safety/sanity. I don't need to play louder that what I mention here. I'm not running a PA show, my room is
about 8 meter long, 4 meter wide and 3 meter high. (not large by any means, which helps) I'm using half of that room for the entertainment area.
Room-a-smaller.jpg

With the sub-woofers added to the mix, I get what I need plus some decent head room. I can play Lullaby at the right level. It remains a cool track.
Bass is never bloated here, that is a surprise for many listeners. What you do hear has enough impact to feel alive. One can follow all bass lines and most unsuspected
listeners hear new things they never heard before. One can feel it, and hear it. It isn't the kick on the chest that steals away your breath, nor am I looking for that.
It has moved my stomach and even flapped my pants though, to my surprise. That first one was a very weird sensation.
 
I figured I'd have to re-analyze the Lullaby song (again) to show how it deviates from most regular songs:

A_Perfect_Circle.jpg


This is a 'chunk' of the middle part of the song being analyzed. What can be seen clearly is how 40 Hz dominates everything. it is way above mid frequency levels.
25 dB still is loud, trailing about 9-10 dB behind. Unless you have a system that is flat, by EQ or design, you haven't heard this song in it's full glory.
JRiver's analyzing gets into trouble and plays this song too loud for comfort and the bass was overpowering my arrays.

It isn't following the patterns of regular main stream songs... never do the mid frequencies come close to the bass parts.

If we take the live version of Hotel California off of Hell Freezes Over and we analyze the Bongo drums:
Eagles-bongo.jpg


It shows a remarkable resemblance to the "Perfect Circle Lullaby" scan.
But if we get further into the song, with background and main vocals:

eagles singing.jpg


We see why JRiver has less problems analyzing this song. Even though that Bongo drum still hits hard, and never fails to impress listeners,
the level of playback of 87 dB on average can be reached (talking about arrays only, no subs) without upsetting anything.
I love the look on peoples faces when they hear this song for the first time at my house. They always look surprised, upon that first bongo hit. Fully awake! (lol)
This song being one of the all time favorites among audiophiles it's almost required to play it. My son fell in love with this song.
It's one of his all time favorites now, possibly his favorite song. I can't blame him, I like it too.
 
A 25 driver TC9 array has a Vd of about 230cm3 each, this falls in between an average 8" or 10" woofer. It is sufficient for normal home music levels when EQ'd but certainly it is no SPL monster. The array runs out of volume potential at the top just as it does at the bottom so adding woofers does not remove that restriction.

These arrays really do produce great sounding in room bass. I bought 2 Dayton RSS390 15" sub drivers, they have never left their boxes, they will eventually but nothing about the sound of the bass I already get makes me in any hurry.

The comparison between an outdoor measurement and an in room measurement I did was quite surprising to me. Apart from some boundary gain and a few dips and bumps they were very similar. More similar than most conventional speakers manage.

Sometimes things work better than the numbers would suggest, for me this is one of those times.
230cm3 is rather sad for a 10 inch at full SPL. Not that we want to run at full SPL.
Also the sensitivity of an 8 or 10 inch speaker is significant more.
Usually we neglect that, but the difference is quite substantial at this point.
Any modern 10 inch will easily do around 104-106dB around 40Hz

But it's not the maxSPL nor the Vd that's important here.
It's the distortion doesn't scale up the same.
Which is a given fact for any small speaker.
Usually this is not that much of a big deal (for like a 6inch or so).
But the differences are quite extreme here.

If you look at measurements from HifiCompass for example, one get an idea.
Even at just a small 2.83V, the distortion flies of the chard.
With 25 drivers per side, you will get 28dB reduction or 34dB in total.
More important, is that for small drivers, rule of thumb is that distortion mostly exists of uneven order.

Also, once again, using any driver way below the Fs does weird things with the Cms.
There is plenty of very easily accessible research available to back that up.
But some people here clearly seem to know everything after all those pages, so I assume that you guys are extremely familiar with all of this.

But most importantly, it has the same issue of any full-range system, which is you are not able to do anything at all about standing waves.
To kind of answer a part of that issue myself (which is the difference between having years of experience and not), is that in this case the listening position is at the opposite wall.
So a EQ notch will do ok'ish (not perfect), although you still will have some issues in the other direction.


But in general, this is all theoretical talk.
I just really don't appreciate at all that if someone has another idea, that's just being slapped down as dumb and so extremely negative.
First of all, the pure thought that a person is gonna read 7000 posts is totally bizarre and insane!
Second of all, there are people on this forum with years of knowledge and experience. Not just me.
Some of them go way back.
Just the pure fact that something like that is not even taking into account or being taken serious AT ALL (by saying that someone just has to read some pages), is from the highest degree of disrespect in my opinion.
Again this IS a general statement, I see this often in other topics from other people as well.

The reason why I am mentioning it, is because it creates a VERY toxic environment.

One were people apparently don't wanna grow and learn from each other.
People apparently also don't want to learn from people who have experience in the field.
Second is the always luring "i know better" attitude of some people.

Let me put it this way, I just respond to people, because of good intentions.
I personally don't give a **** at all if people get happy by listening to a cardboard box or using the most expensive speaker in the world. The only thing I care about is to help them to improve things (if they are open to that), and that they don't get ripped off from their hard earned money.
 
distortion3m.jpg

Distortion graph of array at 3 meter.

But most importantly, it has the same issue of any full-range system, which is you are not able to do anything at all about standing waves.

I think you need to learn about array behavior, because if you knew more about it, you wouldn't be mentioning things like these.
That has been documented ad nauseam and is the sole reason why I invested as much time into this as I did. Clearly you do miss some parts of why an array works.

Sorry, but here you are the fellow who is misinformed and not that well versed on array use inside a home.

Let me put it this way, I just respond to people, because of good intentions.
I personally don't give a **** at all if people get happy by listening to a cardboard box or using the most expensive speaker in the world. The only thing I care about is to help them to improve things (if they are open to that), and that they don't get ripped off from their hard earned money.

We do think, we do read, we do know the basics. What you are suggesting is all fun and games, but it has been tried. Something better was found and that concept stayed. I did try to tell you that but you are so convinced that you are right on this point, yet you are missing one of the sole benefits of using arrays.

You go play with single driver systems, I have no interest in doing that. Not even in those 8" or 10" monsters. As in theory they do very well. It is within a real room that it falls apart. What I do here is meant to use the room, to it's advantage. That part is flying by you like a steam train on steroids. Possibly because you never gave it another thought.

I just really don't appreciate at all that if someone has another idea, that's just being slapped down as dumb and so extremely negative.
My point exactly!
 
Last edited:
Not to be abrasive or mean, that last quote resembles exactly what you have been doing. Personally I do have another idea than the one you presented here.
The one you presented has been the way it has always been done and isn't that foreign to any of us. Heck, more than one array member has done it that way and we are aware of what it presents and does. And I've even done so myself, to have something to compare to.
But it isn't the idea that stuck, and that doesn't seem to bode that well with you, as it goes against your own experience, gut feeling and more.
If you don't have a good grasp on what these little drivers in multiples do different than a single driver, than you haven't even given any thought to it at all.
And you haven't read any of this thread, or watched our sims that make it far more clear, as they do follow the practical measurements very closely.

Maybe start by reading some theory of infinite lines and their difference compared to point source: https://www.diyaudio.com/community/threads/infinite-line-source-analysis.314917/

That's a fun read for starters, but more theory is available. Coming in here with good intention can never be bad. The bad reception isn't due to that, it is because the things you are saying have been said many times, as it comes from conventional wisdom. But we aren't straying that far from wisdom here, if you invest a little time to research what has been done, not only by me as I just combined a few ideas to make my whole. Why are arrays different. Is it just about the sum of 25 drivers or is there more to it?

Spoiler: there is more to it. As soon as you place them in a room.

Back to washing the car. Much more entertaining at the moment.
 
Last edited:
In other news today :)...

Finally got my new rims, my car is dropped and I managed to clean it (partly before it got too dark):
cleanTT.jpg


I'll finish it up tomorrow. Anyway, glad I got it finished (the rims + the drop) before the Scan Speak drivers arrived.
I picked out new rims in Hyper Black that react chameleon like to light and darkness...
It's quite a bit more sporty with Kony shocks and H&R springs and these 19" rims. But after driving many sporty cars for years
that's what I'm used to. I don't know why but I love to feel every bit of the road.
I guess I'm officially in a midlife crisis :D. The car does look and drives good though for a 23+ year old....
it will work out well as a substitute for the 911. It has been in my possession for 4 years, but right now it starts to feel like my car.
If the speakers are up and running again I'll reinstall the stereo from the old car into this one. The standard stereo is a mess.
 
Last edited:
If you look at measurements from HifiCompass for example, one get an idea.
Even at just a small 2.83V, the distortion flies of the chard.
With 25 drivers per side, you will get 28dB reduction or 34dB in total.
More important, is that for small drivers, rule of thumb is that distortion mostly exists of uneven order.
Wesayso and I do not need to look at measurements from HifiCompass or make any extrapolations form his excellent data. We have built and measured the said device up, down, inside, outside and back to front countless times and shared the data publicly.
But in general, this is all theoretical talk.
That is our point that we are not talking theoretically but from personal experience.
First of all, the pure thought that a person is gonna read 7000 posts is totally bizarre and insane!
Indeed but if you did you might have seen that this topic has ben discussed to death before.
Second of all, there are people on this forum with years of knowledge and experience. Not just me.
Some of them go way back.
You are talking to two experienced and knowledgeable members right now, with actual practical experience of the device in question.
Just the pure fact that something like that is not even taking into account or being taken serious AT ALL (by saying that someone just has to read some pages), is from the highest degree of disrespect in my opinion.

Second is the always luring "i know better" attitude of some people.
The first statement is true and unfortunate, the second is how your posts in this thread read to me.
Let me put it this way, I just respond to people, because of good intentions.
Me too.
 
First of all, the pure thought that a person is gonna read 7000 posts is totally bizarre and insane!
Second of all, there are people on this forum with years of knowledge and experience. Not just me.
Some of them go way back.
Just the pure fact that something like that is not even taking into account or being taken serious AT ALL (by saying that someone just has to read some pages), is from the highest degree of disrespect in my opinion.
Again this IS a general statement, I see this often in other topics from other people as well.
That is why there is a wonderful, and often overlooked function at the top of the forum called a "Search" button.

What I find disrespectful is someone barging in at more than 7000 posts thinking their opinion (all theoretical by his/her own saying) is way better and why no one has thought about it!?
I did mention that it had been discussed prior in the thread, but you brushed that aside and continued as the only expert who knows stuff, and you didn't want to see that maybe in this case, there was more to the story than your theoretical knowledge.

They have replied to you with actual data, but you keep coming back, mentioning some information you once saw at hificompass.
If that is your level of expertise that you brushed me away with, than we can safely put this aside and move on...

Hopefully, this little repartee might get you interested to know more about line arrays and seek out better information than what you think is happening.
I did at the time. I built myself smaller 16-driver per side line arrays just because I was curious. I learned a lot.

But I'm not holding my breath.
Cheers!