Building Custom 2way Towers, design questions

[sonenelson]

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 so I have spent the last month researching before posting.

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 with drivers/parts of my choosing 3; The experience gained and having a speaker I can put my name on is priceless to me.

here is my current design plan

2way Tower

42x11x13 WITH 1"MDF
One 3" port (length pending)
2" spacing between -top edge-tweeter-woofer-port, all centered
separate tweeter chamber

- DRIVERS - (1 tweeter 1 driver per tower)

$86 X2 - Hi-Vi RT8II Isodynamic Tweeter http://www.madisound.com/catalog/pro...oducts_id=1491

$174 X2 - Fostex FW208N 8" Woofer http://www.madisound.com/catalog/pro...roducts_id=301

172
348
=$520


- XOVER -

- HIGHPASS - 2nd order linkwitz

INDUCTOR
$34.47 X2 - 1.00mH 12ga FoilQ - .217Ω 1000W - Copper Foil Air Core Coil.
http://www.erseaudio.com/Products/Fo...uge/EAF12-1000

CAP
$34.08 x2 - Audiocap PPT Theta 5.0uF 200V Film/Foil Capacitor

- LOWPASS - 2nd order butterworth

INDUCTOR
$26.12 X2 - .65mH 12ga FoilQ - .156 1000W - Copper Foil Air Core Coil.
http://www.erseaudio.com/Products/Fo...auge/EAF12-650

CAP
$49.64 x2 - Audiocap PPT Theta 10uF 200V Film/Foil Capacitor

- BYPASS CAPS
$4.32 x4 - Audiocap PPT Theta 0.01uF 600V Film/Foil Capacitor

$ ??? - mdf skiing ninja like boards
$ ??? - stand offs

68.16
68.94
99.28
52.24
17.28
=$305.90

(PROBABLY DOWN GRADING TO SONICAPS FOR BETTER VALUE AND LOWER DISSIPATION FACTOR. Also planning a cascading bypass cap design http://www.northcreekmusic.com/Bypassing.html http://www.skiingninja.com/Articles....9&Redirected=Y )


-PARTS-

$12 X2 - 3" FLARED PORT
$4+/ X2 - BINDING POSTS
$41 - Belden 1311A 12/2 OFHC Oxygen Free High Conductance 50 ft http://www.broadbandutopia.com/1311a50.html


MIN GRAND TOTAL $898


-EXTRAS-

$38 X8 - NOREZ
http://www.gr-research.com/index.asp...ROD&ProdID=103
+/-$4 X8 - BANANA PULGS
$ ?? - FEET/OUTRIGGERS

304 - NOREZ
32 - BANANA PLUGS

=$ MAX GRAND TOTAL??

(I use CAPLOCK in my notepads so I know what I write vs copy/past)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I chose the isodynamic ribbon tweeter because I like it's properties and most of what I have read about it.
The fostex woofer was one of few left after a long process of elimination.
I have researched bypass/cascading caps and everything I have read makes me want to try them for myself.
these will be the first 2 of 6 for a HT setup. I will be using subs/low frequency transducers but would like these to be as full range as they can be without sacrificing vocal clarity .
My original goal was studio quality, low distortion, high sensitivity, full range towers good for Home Theater and Music.
by budget is about $1000/pair not including "extras"



the bottom right graph shows three different port lengths I am debating. The top right graph shows two of the port lengths, and the higher 'high end' is with the recommended caps/inductors the lower is with the values I have chosen for a smoother crossover.


- Questions -
What do you think?

Should I sacrifice some low end and find a driver with a higher sensitivity for a flatter response curve/better matching with tweeter or can I level things out with an equalizer?

How well will the fostex driver reproduce vocals? how well if I Increase the bass level (a lot)? how well with out much equalizing? vocals are the most important in HT audio to me.

Any suggestions on improving parts quality or price on the cables, Xover, misc parts, etc?

What will the total power handling of this setup be? I plan on using the Emotiva UPA-7 SEVEN CHANNEL AUDIO POWER AMPLIFIER
125 watts RMS x 7 into 8 ohms | 185 watts RMS x 7 into 4 ohms

should I tune the box with the middle 30hz line or would a 52hz tuned port be better?

Any other suggestion comments questions are welcome and very much appreciated!


Lots of questions/ long post but thanks in advance for any advice short or long.

[doug20]

Why did you pick those drivers?

I have no idea about them, Im just curious!

[sonenelson]

originally I wanted to keep the drivers under $100 each and was thinking of doing a 2.0 way or 2.5 way tower with 6.5" drivers but couldn't really find much in the way of a midrange/woofer that had the specs I was looking for; paper cone, high sensitivity, 30hz to 3000hz range, above average power handling, good Xmax. so to simplify things I decided a 2.0 way speaker would be better. the 8" fostex has good stats has been one of the best in my models/simulations and also looks cool( I think). Also as far as I know fostex has good value in the price to performance ratio.

For the tweeter I wanted something with a range up to 40K, to begin with, but after reading about the isodynamic/planar ribbon tweeters I decided that for under $100 they were the best for me. Also the Hivi ribbons are used in some high end speakers.

the rt8II in this one
Ed Momkus reports the feat that is the $15,000 Coincident Speaker Technology Total Victory IV speakers
http://www.dagogo.com/CoincidentTotalVictoryIV.html

And the lesser isodynamic HIVI ribbons in these
Swan M1 reference class minimonitor $729
http://www.theaudioinsider.com/produ...products_id/28

Reimer Tetons GS
http://www.6moons.com/audioreviews/r...oadtour10.html

The HIVI/Swan site describes there tweeter best
http://www.swanspeaker.com/product/htm/view.asp?id=18

If I were to upgrade the woofer I would probably go with this SEAS Excel W22NY-001 http://www.madisound.com/catalog/pro...oducts_id=8176
But I'm not sure if it would be worth $70 more ?; if it would over power the rt8II?, and I can't get a very smooth crossover in Xover pro 3 using any 2nd order Xovers.
If I were to upgrade the tweeter I don't know what I would upgrade to. I like these http://www.zaphaudio.com/ZRT.html ZRT 2 way towers but I don't believed Scanspeak to be a High value brand although they do seam to be good sounding.

however with the seas 8"woofer/RT8II the best I can get the crossover is with a 4th order which would also raise the cost and is not much better than the the fostex.
This is the fostex tuned to 60 hz compared to the SEAS tuned to 50hz.

fostex in yellow SEAS in purple. I don't know why but the fostex fw208N has been the only speaker to get a 2-3db boost at the tuned frequency.


More questions

Would a sealed enclosure really make a difference in distortion in the 85hz-2000hz range vs a 60hz tuned port?

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

If I tuned the port to 60 hz would the tweeter or woofer max out first(with/without equalization)

Is and Lpad worth using? when should someone use an Lpad? in simulations it only drops the very high end and does not make the cross over any smoother. It seams to me I would be bette off using and equalizer to lower treble.

[chris661]

Have you tried lowering the tuning frequency for the fostex?
It's hard to believe it will make a 2-3dB peak anywhere on the frequency range.

It is rare for tweeters to go before the woofers. There is very little power behind them and the power ratings on them are only so they can compare to woofers.

Have you considered a high-pass for these? around 10Hz maybe to stop any really low bass damaging the drivers (it would be well below port tuning, so driver would bottom out quickly).

If there's too much treble, get another woofer.

[sonenelson]

I have changed the drivers to 2 SEAS 7" woofers and Xovers to 4th order. this gives me much better modeling results in Bassbox/Xover pro.

I have considered using a high pass Xover on the woofer but was unsure if it would be necessary or worth it.