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

I have terminal strips in divided compartments in my line arrays. 3 way actives with external servo subs.

Only picture I have of the terminals..

. P_20190617_123532.jpg P_20200217_130306.jpg
 
I've spent the weekend reading and its almost impossible to take all the information in.

I posted another thread Looking for a project - large room, large sound

Line Arrays were our first thought and after advice/checking out things for our room the Line Array does make the most sense.

I read through your website but are you making the CAD for the pieces available or selling them?

Is there a different driver decision you would have made at any point in time. If your driver budget was 2X, 3X, etc?

Would you have chose a larger driver given the chance or adding a tweeter line as you allude to?

Can the front face be broken into 2 or 3 sections? We have always wanted a 2D CNC and finally are going to get one but it is limited to 29.5" square.

Very impressive passion for something.
 
@troystg, a smart choice! Giving you options down the road!

@ericspt, I did see your thread and the mention of line arrays, both straight and CBT shaped arrays were mentioned.

Sorry that this thread became as long as it did :). But there's lots of good info in it, both on what to do and what not to do :D.

There were a couple of warnings that came along with straight arrays like I have here. You need EQ! That's not negotiable. Preferably the FIR kind, as that gives you a lot of power to adjust these to your liking.

I haven't shared the templates I used. At some point I did consider making and selling speakers, but I don't see it happening. The shape can be reproduced though from all drawings and pictures I posted. I'm still a bit reluctant to share them. You should think long and hard if you want to build stacked arrays like I did. You'd need to do something to prevent what happened to me, a cracked enclosure due to seasonal changes. I have been successful to repair it and prevent it from happening again, but you'd need to be a little crazy to build it like that.

I wouldn't want a segmented baffle. The drivers are mounted as close as possible (center to center) and there simply isn't much room to make sure everything is sealed properly.

On the driver front? I did not get the driver I used based on price. I based it on the published results in many tests etc, it is a marvelous driver. You'll find some other opinions, no doubt, but I wouldn't hesitate one moment to use it again. An upgrade could be the TG9 FD10-08, but I haven't seen them in stock lately, you can get them in quantities of 2000 though :eek:.
The 4 ohm sister to that one (TG9 FD10-04) is more easily available, but I'm not quite sure it is performing as good.

Another, way more pricey option would be the Scan Speak 10F, in an 8 ohm shape. There are a few versions, some of them have a closed off spider which wouldn't be ideal (if you want to make bass with them). Plus the driver has a circular frame which needs to be "shaved" to get the drivers closer together.

The TC9 simply is an honest, well designed driver and it looks like it was made for this job. In your relatively large room I'd advise using subs for the bottom end. I could do without easily in my ~8 meter x 4 meter room, but others with bigger rooms were less lucky/successful. I'd aim for a 2 litre to 2.2 litre enclosure for each driver.

I've picked this driver/size to be able to get a full range sound out of a single (well, 25 of them) driver. An array with crossovers is simply going to be a different beast. And quite honestly, I don't think I'm going there, at least not unless we'd find a way to keep all that is good in this full range type of array.
This driver size is the biggest I would consider for this job. You need a special combination, clean performance (no ringing up top) and enough x-max. Check out the different line arrays by Halair, fluid, nc535, koldby, OPC and many more that I forgot to mention.

In my humble opinion, there is a lot to like about these arrays, and I do believe part of it is the absence of a crossover.

While I'm currently playing with filters etc, that is just curiosity driven. It may make things better, but sometimes I do wonder why I even try. This speaker has been more than satisfying for over 5 years of use.

There simply is more to learn, and that's part of this crazy hobby for some of us.

Do think it trough, most important: how will you solve the needed EQ?
I have a PC Workstation that does that part for me, with a lot of handy programs. But it isn't for everyone. My other half does not dare turn on my system (not that I'm sad about that ;)). My son has no problems with it though.

You could do the EQ with other tools, but a PC is one heck of a tool to play with. As a former IT professional it was an obvious choice for me. As that allowed me to make it into my own personal play-garden. The PC is running all audio tasks, doubles as my Home Theater server and is the heart of 6 channels of audio, steering the two main arrays, the subwoofers and 2 ambient channels. I still have 2 more channels available should I ever get bored. :p

As I'm a bit long winded in my response already I'll stop here to not overload you with information. Feel free to ask more questions though. I'll help where I can if you decide to go this route. And there are other generous members with arrays that I'm sure would chime in as well.

Plan it good, it might just be the last speaker you'll ever need! Did you see the links in the first post of this thread? That's an easy way to navigate through the enormous amount of info, and there are some reviews by a few visitors, which should provide some idea of what to expect.

You wanted a project for you and your wife, right? Well... this sure would give you something to do! :D

**edit** the driver mark100 mentioned, that are used in Jim's CBT's sure are another good option. more expensive, but they can be mounted closer together which is an advantage. They won't do the bottom octaves, you'd definitely need subwoofers. (preferably more than one to keep up)
Check out nc535's thread as he used the same driver in his corner arrays.
As subwoofers would be advised in a larger room anyway, it sure could be another valid option.
 
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@ericspt, I did see your thread and the mention of line arrays, both straight and CBT shaped arrays were mentioned.

SNIP!

You wanted a project for you and your wife, right? Well... this sure would give you something to do! :D


Thank you for all the info. EQ is not a problem. I noticed a lot of talk of Jriver. I run a Roon server with Raspberry Pi's with a re-clocking daughterboard as Roon Bridges into various DACS or Integrated amps. I am not a fan of Jriver, I've tried it in the past but just never cared for it but that is just me. Roon integrates your local library with Tidal which is huge for me. I can play an incomplete album and it will pick up the missing tracks from Tidal seemlessly plus the phone app is well integrated for a whole house system since we have 4 zones.

I do not know what Roon offers as far as EQ but I assume I can put an EQ in the middle somewhere.

We both come from manufacturing/engineering and technical backgrounds so I'm not too concerned about the construction part although she is the more creative/patient one and I am the more technical in vision, she is more technical in doing.

What we want is something uncompromised while still doing it ourselves.

As far as the last speaker we will ever need...we still have our main listening area in the basement :)

Thanks for your thoughts.
 
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I just love JRiver, because it allows me to do this:
attachment.php

The subwoofers are missing in the above flow chart. this is just the stereo/ambience setup.

With 65356 taps FIR filters and I'm using all the EQ banks within JRiver plus I added a few :). But hey, I'm just a little bit crazy.

Be sure you can run plugins, like convolution etc, you'll be alright.
I'm on the extreme end of tinkering I think, it that wasn't obvious already. ;)
 

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I just love JRiver, because it allows me to do this:

The subwoofers are missing in the above flow chart. this is just the stereo/ambience setup.

With 65356 taps FIR filters and I'm using all the EQ banks within JRiver plus I added a few :). But hey, I'm just a little bit crazy.

Be sure you can run plugins, like convolution etc, you'll be alright.
I'm on the extreme end of tinkering I think, it that wasn't obvious already. ;)

So sounds like it from what I read as long as that particular Roon bridge is a Windows based PC. I originally had Lenovo Nano's as end points but switched to RP's because the daughter board fixed a lot of issues with USB timing and control from the phone was better.

They specifically talk about REW but if Roon is just the source anything should work....except JRiver :)

If the EQ App just sits before the USB audio driver and adjusts what ever is playing from the source then I should be able to do whatever correction is necessary only limited by the software itself.

I need Room EQ now as it is since the Cambridge CX81 does nothing for subwoofer correction, just hasn't been something I've really looked into as its not that bad because our volume level is pretty consistent and I've adjusted it the sub itself.
 
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I like JRiver for what it means to me, a platform I can build upon. Adding VST plugins to make certain things more accessible etc. I got used to the user interface, but it's the DSP section where I live, really. Jriver can run as a WDM driver, meaning it could be chosen as the standard Windows driver and play anything from other sources.
Only video would need more work, but I even ran Netflix trough JRiver with manual audio/video sync.

Not trying to promote it though. One would only need access to all channels and be able to run a couple of plugins, even a plugin host like Metaplugin could provide you that, inside a plugin host program like that you can route whatever you want or need.

There are a couple of freeware plugin hosts too, Metaplugin is just what I ended up using.

In your quest for speakers, you can go in a lot of directions. Seeing as you are both technical, you might also look at the Small Syns from bwaslo as an option.
 
Couple of points based on the last few posts. Most CNC machines with open ended beds can cut the panels in sections if reference dowels are used, like halair did with his and many youtube videos will show. This removes the restriction on the baffle height being cut with CNC.

Jriver is an awesome platform for DSP processing. Roon is a long way behind on that front. The two can work together though to get the best of both. Dallas Justice on Audio science review has an active M2 setup with Jriver and roon together to run multiple convolution files from Acourate.

Jriver can apply DSP processing to any streaming device I use volume levelling when streaming to my Sonos devices but anything that can be added to the DSP studio can be streamed too. It isn't quite plug and play but once you find the right settings you will be away.

Arrays need EQ measuring and tweaking to get great sound. If you do that they will reward but if you skimp on it or can't be bothered go with something else.
 
Output of the corrected array (with notches) with a single driver FIR correction on it:
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(same circumstances as the alternatively wired array from a few days ago)

Plotted from -102 to + 102 mm, every 17mm.

No room reflections present in this prediction. It shows well behaved output up to high frequencies, fitting within +/- 1 dB over a wide range. With the advantage that you get to keep most of that with floor and ceiling reflections.
 

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It seems one cannot do too much sims. The sim above has thought me something new.
If I drop my listening axis by 2 cm, the top end will behave even closer to the one driver result. Which means all of the other vertical angles will be slightly better behaved as well.
I never would have figured that out by myself.
It's quite specific to my array and driver distances, filters used etc. But it would even matter in an unshaded array.
One of the objectives in my specific filter generation was to get closer to that one driver result with my correction. That's where I kept a close eye on what shape the correction would show. By running the array with the filter generated for one driver I could see which height was close to flat in the top end. that ends up as 980 mm from the floor.
 
Don't worry, as you get older you will lose some height :)

Its a lot of work to take as much data as you plotted in the previous sim. Don't you wish you could script it!

I could script it, but that's a lot of work too :D.

As long as the weather isn't cooperating, I guess I'm still trying to study the plots...
(with plenty of time to do that, while I try and make sense of it ;))
 
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Here's a comparison of vertical heights between a FIR correction at 1000mm and 980mm.

First the original correction height:
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compared to the position 20mm lower:
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The listening positions are exactly the same, only the correction height is different. So no sawing of chair legs etc ;). Not even an adjustment of the array height.
(don't look at results below 1 KHz, as I didn't bother straightening out the prior 1000mm correction there)
The absorption of floor and ceiling are set at -6 dB.
 

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I tried the vertical averaging (for a line array of all things) and I decided it was better to EQ at my preferred listening height and, as you said, tweak the EQ to even it out over a limited range. Otherwise I ended up with a good average but my nominal height response had ripples, albeit small ones.

I know I have been putting a lot of effort into various other designs but I'm seeing how hard it is to beat these line arrays.