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Building Custom 2way Towers, design questions

post #1 of 13
Thread Starter 
I am designing a custom 2 way tower from scratch and am at the point that I need some advice, This is my first Home Theater project. I have custom built dozens+ of subwoofer enclosures for cars, but custom crossovers and matching tweeter's with woofers/midranges is unfamiliar territory, I have over a month of researching a couple hours every night but still have a lot to learn.

I have read a lot of diy threads and I don't want to go with a proven design because 1; This is fun for me 2; I was not able to find a design using the parts I wanted to use and would like to be able to make future designs of my choosing 3; The experience gained and having a speaker I can put my name on is priceless to me.

my current design plan is pending but I plan on it being a simple 2 way tower with with a 8" woofer and the widest range planar/isodynamic tweeter. As of now my top choice is the BG NEO8 with a Peerless or SEAS woofer. crossed as low as possible 500Hz-1kHz. I am planing on a sealed enclosure with separate tweeter chamber for tight fast bass. Separate subwoofers will be used to supplement the LFE's.

>EDITED<<br />
these will be the first pair for a HT 7.1 setup. I will be using subs and later low frequency transducers but would like these to be as full range as they can be without sacrificing clarity/ causing distortion.
My original goal was studio/pro quality, low distortion, high sensitivity, full range towers good for Home Theater and some Music. but since I believe music is harder to faithfully reproduce then HD HT sound these will be a experiment to suit my taste for ultra high definition, resolution and fidelity in a HT environment.
by budget is about $1000 for the first pair

- Random Questions -


Would a sealed enclosure really make a difference in distortion in the 85hz-1000hz range vs a port design?

What difference does it make if I placed the port lower? I prefer forward or down firing because they may be closer to walls than I would prefer.

Any suggestion comments questions are welcome and very much appreciated!



Edited: edited first post some post may not make sense since... oh well better than starting a new post.
post #2 of 13
Well first off, what do you plan on using that FR spike before tune for? There's a lot of better choices for woofers in that price range IMO. Given your available volume, a 2.5 way MMT with 6.5 inch woofers is a better option. If your heart's set on a 2way with an 8" woofer check out this one



http://zaphaudio.com/8test/compare.html

If you want to go LR2 at 2k, it's a much better option and a SEAS 27TDFC waveguide modified would be a solid match.

In 2cuft ported, you can tune it to 35hz with the Visiton. making it a solid performer for 2 channel music....which i suppose is your reasoning for the extension?
post #3 of 13
Thread Starter 
The low end extension IS so my system can double as a HIFI stereo for music and front LR for HT.

I'm not set on 2.0 way. A 2.5 TMM design with 6.5" drivers is my second choice. but since this is my first HT project I have explored the 2.0 way design much further. some of the complications of the 2.5 made the 2 way seem a better option for a first time experiment.

I get what you're saying about better options but what did you mean by the "what do you plan on using that FR spike before tune for"?
post #4 of 13
That's a heck of a lot of money for a modelled FR that looks that bad!
Have a look at an MTM of dayton RS150/s (or 180's possibly) and a vifa xt25 tweet.

Also have you calculated your impedance correction for your XO?
post #5 of 13
Quote:
The experience gained and having a speaker I can put my name on is priceless to me.


Yes, that would be cool but its your first project and with that your lofty goals may not pan out

Those drivers do not seem like good choices at all. There is a reason some drivers are picked all the time for projects. HINT: Its because they are great drivers
post #6 of 13
Thread Starter 
Quote:
Originally Posted by mayhem13 View Post

Well first off, what do you plan on using that FR spike before tune for? There's a lot of better choices for woofers in that price range IMO. Given your available volume, a 2.5 way MMT with 6.5 inch woofers is a better option. If your heart's set on a 2way with an 8" woofer check out this one



http://zaphaudio.com/8test/compare.html

If you want to go LR2 at 2k, it's a much better option and a SEAS 27TDFC waveguide modified would be a solid match.

In 2cuft ported, you can tune it to 35hz with the Visiton. making it a solid performer for 2 channel music....which i suppose is your reasoning for the extension?

The plan I'm sure will change many more times before I put it into production but with Bassbox/xover pro I got much better modeling results using 2 SEAS 7" woofers so I think a TMM or MTM design will be better. I know I have a lot of research and learning yet to do I am taking any and all suggestions.
post #7 of 13
Which seas woofers were you looking at?
post #8 of 13
You are wasting your money on expensive XO components if you're designing the XO without actual frequency response measurements of your drivers in your enclosure.

Also, as others have mentioned, this woofer is a lousy choice for a full range HT speaker, especially with 3.5 mm of excursion.

Good luck,

Regards,

Dennis
post #9 of 13
Thread Starter 
Quote:
Originally Posted by djarchow View Post

You are wasting your money on expensive XO components if you're designing the XO without actual frequency response measurements of your drivers in your enclosure.

Also, as others have mentioned, this woofer is a lousy choice for a full range HT speaker, especially with 3.5 mm of excursion.

Good luck,

Regards,

Dennis

the Fostex is lousy? I agree it's not the best choice but it has a 6.5mm Xmax?

I was looking at this SEAS - SEAS Prestige ER18RNX (H1456) 7" Reed Paper Cone Woofer http://www.madisound.com/catalog/pro...oducts_id=8181
And I am looking at some Peerless 6.5" to 8" inch woofers now.

I would prefer to keep it a 2.0 way design, and I don't plan on using the most expensive Xover parts but thought sonicap was one of the best for the money and I don't mind having extra parts for another project if this one needs tweaking, the inductors I may also change depending on if I use a 2nd order or 4th order Xover.
I also do plan on buying measuring equipment for the tweaking and I am researching ways to use other peoples real world measurements to design a better starting Xover.
post #10 of 13
Quote:
Originally Posted by sonenelson View Post

the Fostex is lousy? I agree it's not the best choice but it has a 6.5mm Xmax?

I was looking at this SEAS - SEAS Prestige ER18RNX (H1456) 7" Reed Paper Cone Woofer http://www.madisound.com/catalog/pro...oducts_id=8181
And I am looking at some Peerless 6.5" to 8" inch woofers now.

I would prefer to keep it a 2.0 way design, and I don't plan on using the most expensive Xover parts but thought sonicap was one of the best for the money and I don't mind having extra parts for another project if this one needs tweaking, the inductors I may also change depending on if I use a 2nd order or 4th order Xover.
I also do plan on buying measuring equipment for the tweaking and I am researching ways to use other peoples real world measurements to design a better starting Xover.

Sorry, I read the Fostex spec as 6.5 mm peak to peak, not peak. 6.5 mm is OK.

BTW, measurements are not really for tweaking, they are for doing the intial XO design.

Regarding an earlier question you mentioned. An L pad is used to lower the volume of the tweeter while maintaining a constant impedance to the tweeter XO. You need to lower the tweeter level across it's entire frequency range to match it to the level of the woofer, in this case once you factor in about 4-5 db of baffle step compensation on the woofer, your tweeter is going to be 10 db louder than your woofer. Hence the L-pad.

Good luck

Dennis
post #11 of 13
Thread Starter 
Yes I didn't mean tweaking as much as fine tuning and design experimenting

As I continue to research and learn my entire plan is pretty much scrapped. I would like to do a proven and well documented 2way design for my first project but have not found the right one yet.

Does anyone know of a proven or well documented 2way design for a planar/isodynamic/ribbon or bending wave driver? or a 2way NEO8 design?
post #12 of 13
Quote:
Originally Posted by sonenelson View Post

As I continue to research and learn my entire plan is pretty much scrapped. I would like to do a proven and well documented 2way design for my first project but have not found the right one yet.

Does anyone know of a proven or well documented 2way design for a planar/isodynamic/ribbon or bending wave driver? or a 2way NEO8 design?

Let us know when you get to waveguides:

http://www.avsforum.com/avs-vb/showthread.php?t=1140175
post #13 of 13
Quote:


Does anyone know of a proven or well documented 2way design for a planar/isodynamic/ribbon or bending wave driver? or a 2way NEO8 design?

how about a 2way with a ESS AMT from parts express and a TD15M from AEspeakers.com

Zilch is right though, many of us are discussing waveguide designs and we are looking for 2-way designs.
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