Any Good DIY projects for center channel?

[TLS Guy]

I am very interested in this concept of coaxial speakers for an entire 5 channel system (at least center and mains). It seems like building 3 of TLS_Guy's center channel TL design would make a great front soundstage.

I have always been interested in TL designs but the designing of said speakers is a little over my head. A TL that I could mount to the front wall is right up my alley of what I'm after for my future system.

Very cool thread.

Here are the plans. I would put the file on a CD and that have a large set of plans printed at Kinkos.

The stuffing density is 0.78lb of polyfill/cu.ft.

These pictures may help with construction.

 

[Guiria]

...What polypropylene drivers would you recommend...

??

Given the cost of the stand alone coax loki driver, is there a cheaper replacement that won't adversely affect performance? You would think there is a similar driver without the tweeter built into it.

 

[TLS Guy]

??

Given the cost of the stand alone coax loki driver, is there a cheaper replacement that won't adversely affect performance? You would think there is a similar driver without the tweeter built into it.

I have searched and searched for a driver, with close TS parameters, to avoid using a coaxial for the fill driver. I have not found one that can match the all important VAS, Fs, Qt and sensitivity. One of the things that makes that driver unusual is the low Fs for the size of driver.

There are lots of good PP drivers out there, but then you need a different line. The SEAS are the only decent OEM line of coaxial speakers.

If you don't use a coaxial, then you end up with the horizontal MTM, which is something to avoid. The other solution is a three way, but then you need a mid range driver with a large bandwidth, that can be crossed over at 400 Hz and 4 kHz, so you don't have drivers separated in space, crossed over in the speech discrimination band. You then have a costly mid range unit, and three other drivers besides, with a costly three way crossover.

The other problem is that you end up with a closed chamber for the mid range within the line. If you make a standard ported enclosure, you can correct the step response with a different driver, by having the drivers in isolated compartments, but that is obviously not practical for a TL.

I will bug SEAS again and try and persuade them to make the driver without the tweeter, to use to correct the step response.

 

[Guiria]

Thanks for the healthy explanation. I should have known that you would have already exhausted all options and found the best performing configuration for the given project

Now, how do I convince my wife...hmmm

 

[Guiria]

For TLS...

How would you say your center channel handles dynamic movie passages? If I were to build these as mains as well will they sound full at moderate to loud dynamic levels? Would they provide that feeling of tight strong midrange on gun shots, etc?

I am about an 80/20 movies/music guy on my system so movie performance is key.

 

[lsiberian]

For TLS...

How would you say your center channel handles dynamic movie passages? If I were to build these as mains as well will they sound full at moderate to loud dynamic levels? Would they provide that feeling of tight strong midrange on gun shots, etc?

I am about an 80/20 movies/music guy on my system so movie performance is key.

I imagine anything that TLS uses in his home will be amazing in your place. In fact If I had the place and money I would build 7 of these and use them for all my speakers.

These drivers are very good, but if you have a large space you may need more drivers.

 

[Guiria]

...but if you have a large space you may need more drivers.

My room is about 2300 cubic feet.

 

[lsiberian]

My room is about 2300 cubic feet.

I think you could easily fill the room with the drivers mentioned. It also may be possible to do 3-ways with those drivers. If that's your fancy.

They do take a lot of power so be aware of that.

 

[TLS Guy]

For TLS...

How would you say your center channel handles dynamic movie passages? If I were to build these as mains as well will they sound full at moderate to loud dynamic levels? Would they provide that feeling of tight strong midrange on gun shots, etc?

I am about an 80/20 movies/music guy on my system so movie performance is key.

It will handle it better tan most 2.5 way towers with similar sized drivers. If you want something with higher power, you will have to step up to the expense of the SEAS Excel drivers, Scanspeak drivers or the Morel Line.

I can drive my center line very hard. Biamped with 500 watts, it performs very well in movies.

 

[Guiria]

good to know.

I would speculate that the coax build would be sufficient for my listening preferences in my 2300 cubic foot room.

 

[lsiberian]

good to know.

I would speculate that the coax build would be sufficient for my listening preferences in my 2300 cubic foot room.

If not you will need to up your budget significantly.

The Excel Drivers aren't cheap.

But driving the speakers to full potential requires an external amp with a lot of power.

 

[TLS Guy]

good to know.

I would speculate that the coax build would be sufficient for my listening preferences in my 2300 cubic foot room.

Just one word of caution. Since the tweeter is at the base is the cone serving as a wave guide, the tweeter dispersion is restricted as you move 30 degrees off axis. The off axis response mirrors the on axis response well except for the matter of off axis HF roll off. My researches showed this to be desirable in a center channel speaker, to reduce interference with the left and rights. However it having a speaker with broader off axis dispersion might be desirable in the mains. There are some cost effective drivers in the SEAS prestige range and the Peerless line which are suitable for TL loading.

 

[Guiria]

If not you will need to up your budget significantly.

The Excel Drivers aren't cheap.

But driving the speakers to full potential requires an external amp with a lot of power.

The budget has already been up'd and exceeded

If I did this I would end up with a Behringer DCX2496 so that I could actively control the step response for the center, and then most likely for the mains as well, and while I'm at have seemless integration with my sub. That means external amplification for everything.

I wonder how well a single A500 would run this center channel. I could wire in parallel the main coax driver with the fill driver and get 500 watts at 4 ohms. That would be the cheapest method for amplication that I can think of, but cheapest always isn't the answer, as I've already learned.

My current DIY bookshelves would become my rear surrounds. Man, just thinking about this system is making me drool...I love it

 

[Guiria]

Just one word of caution. Since the tweeter is at the base is the cone serving as a wave guide, the tweeter dispersion is restricted as you move 30 degrees off axis. The off axis response mirrors the on axis response well except for the matter of off axis HF roll off. My researches showed this to be desirable in a center channel speaker, to reduce interference with the left and rights. However it having a speaker with broader off axis dispersion might be desirable in the mains. There are some cost effective drivers in the SEAS prestige range and the Peerless line which are suitable for TL loading.

Are there other drivers in the SEAS Prestige line that would allow a TL enclosure that is close to the size of the center channel to be used as mains? Putting these on or in the walls would be ideal.

 

[TLS Guy]

Are there other drivers in the SEAS Prestige line that would allow a TL enclosure that is close to the size of the center channel to be used as mains? Putting these on or in the walls would be ideal.

Yes, almost certainly. I think an MTM layout would work well for an in wall solution. You really do need to limit vertical dispersion.

I will work on this next week. For a TL you have to do the alignment the old fashioned way.

What are the ranges of height and depth you can tolerate, and can the enclosure protrude from the wall at all? If so how far.

 

[Guiria]

Yes, almost certainly. I think an MTM layout would work well for an in wall solution. You really do need to limit vertical dispersion.

I will work on this next week. For a TL you have to do the alignment the old fashioned way.

What are the ranges of height and depth you can tolerate, and can the enclosure protrude from the wall at all? If so how far.

That would be great, however, I just want to let you know that building the mains would be something I do down the road so of course, if you've got the time great and it would defnitely be appreciated but I wouldn't be building the design for several months.

I'm hoping I can convince my wife to allow me to build the discussed center as my bday present coming up in April. Now that would be cool.

Now on to your questions.

What are the ranges of height and depth you can tolerate

About 7' of wall space until the wall starts to angle in towards the ceiling. I alsohave a chair rail that would need negotiating through and around if the speaker were taller than about 39 inches. The walls have a sloping ceiling behind them and about 8 feet deep of space at the base of the wall. The other side is dead attic space so reasonable speaker depth shouldn't be a problem.

can the enclosure protrude from the wall at all? If so how far.

Yes, in fact I would prefer the enclosures to protrude some to give them their defined space.

Perhaps a picture or two would be helpful

 

[Mike82]

I have been doing a lot of research for my mains the last couple weeks considering mine are sold and need to be replaced within 2 to 3 weeks. I have come up with this as my best option for price vs performance http://www.geocities.com/woove99/Spkrbldg/ER18RNX_MTM_2Way.htm
I am not sure if his calculations are correct on the crossover or the box size but these are the speakers I am looking at to do a MTM design. Does this look good to you TLS Guy.

On a side note what are your guys thoughts on used speakers I might have the option of buying 2 SEAS Excel millennium tweeters http://www.madisound.com/catalog/product_info.php?cPath=45_229_324&products_id=779 and 4 SEAS Excel 7" Woofers http://www.madisound.com/catalog/product_info.php?cPath=45_228_256&products_id=784 for $500. Which would be a steal but I am not sure if speakers start to go down hill after so much use.

 

[TLS Guy]

I have been doing a lot of research for my mains the last couple weeks considering mine are sold and need to be replaced within 2 to 3 weeks. I have come up with this as my best option for price vs performance http://www.geocities.com/woove99/Spkrbldg/ER18RNX_MTM_2Way.htm
I am not sure if his calculations are correct on the crossover or the box size but these are the speakers I am looking at to do a MTM design. Does this look good to you TLS Guy.

On a side note what are your guys thoughts on used speakers I might have the option of buying 2 SEAS Excel millennium tweeters http://www.madisound.com/catalog/product_info.php?cPath=45_229_324&products_id=779 and 4 SEAS Excel 7" Woofers http://www.madisound.com/catalog/product_info.php?cPath=45_228_256&products_id=784 for $500. Which would be a steal but I am not sure if speakers start to go down hill after so much use.

No they will not go down hill unless they have been abused. That deal is too good to pass up. with those drivers you can build the Thor TLs. You cant go wrong with those.

 

[just-some-guy]

Here are some links to my pics considering I could not just get them to show up.
http://img15.imageshack.us/my.php?image=img1582j.jpg

http://img13.imageshack.us/my.php?image=img1581c.jpg

lovin that stand

 

[Guiria]

What are the ranges of height and depth you can tolerate, and can the enclosure protrude from the wall at all? If so how far.

I think this will help me answer the question more clearly...

This is the wall the speakers would go into or on. There is plenty space behind the wall. I planned on mounting the main speakers above the chair rail while I will put the center just below. Wall above the chair rail is an absolute 44.5 inches but at that height no in wall mounting would be possible because of the sloping roof behind the wall. Of course this will happen when I get a flat panel and ditch the entertainment center. Everything will go into the wall at that point.