Advice on center setup

[Pat.M]

Hi guys,

Been reading around different audio forums for the past few days now and decided to register here because you guys really now what ur all talking about. How do I know this? well its because half the time I have no idea what ur all talking about :??
I've recently caught the bug of wanting to learn how to set up a well tuned speaker system.
After searching around for quite some time I've decided to go along with a horizontally WMTW center speaker. The L/R will follow shortly after.

-For the woofers I chose 2 W18 from Seas
-A TB W4-1337sd for the 4'' mid
-Finally I went for the ScanSpeak D2904/9800 tweeter.

This is where I need your help understanding which setup would be best to mate these to achieve a clean and balanced sound. I have skills in woodworking, so the box construction won't be a problem. May need help on volume size and design.
As for circuitry(resistor and cap formulas), well I forgot most of it that I've learned from elevator school :roll: . So your thoughts on xovers will be much appriciated.
Shopping with my cash is out of the question here for you guys since these items have already been paid for. sry

[Jed]

The driver choices are certainly nice. However without a crossover or the ability to measure it's going to be difficult to get good sound regardless of the drivers. Do you know someone that can measure?

[Pat.M]

No Jed, I don't know anyone who can measure. Would a crossover and enclosure be needed in order to take readings? If so, how can I get started to get anywhere close to the proper setup?
How acurate is Bassbox and X-over pro software to achieve a well tuned enclosure and xover?

[Jed]

No Jed, I don't know anyone who can measure. Would a crossover and enclosure be needed in order to take readings? If so, how can I get started to get anywhere close to the proper setup?
How acurate is Bassbox and X-over pro software to achieve a well tuned enclosure and xover?

I recommend Unibox. It's free and is always spot on for the simulations for box design. It will not help for crossover design however. That needs to be done with the drivers mounted in the finished box. Something like ARTA is great for the measurements. Then, after you measure you have to import the files into a crossover modeling program, such as LSPcad. That's not the end of it... knowledge of crossovers and circuitry is a must so that you can design an appropriate electrical circuit.

Textbook crossovers are a No-No.

Jed

[Curt C]

The W18’s like a fairly large enclosure. To give you an idea of how large, look at the Statement CC design, which incidentally also uses the same mid you chose.

Building the Statement CC enclosure as a sealed design would suit the W18’s quite well. This would result in a reasonably useful f3 in the low 60’s, and likely acceptable for your HT purposes. A vented enclosure for the W18's would require nearly double the volume, but would have a much lower f3. Of course the Statement CC is already a pretty large enclosure as it is.

As Jed alludes, crossover design is not necessarily straightforward, nor simple. The learning curve and calibrated equipment necessary for proper driver measurements alone can prove to be daunting for the uninitiated. That said, if you are up to the challenge, I’m sure the forum will be glad to offer moral and technical support as necessary.

To assist you on your speaker design sojourn, I’d recommend reading the following books, likely in this order:
Speaker Building 201 by Ray Alden
The Loudspeaker design Cookbook by Vance Dickeson
Testing Loudspeakers by Dr. Joe D’Appolito

They should all be available from Parts Express, Madisound, or Old Colony

C

[Pat.M]

Thanks for the advice Curt. I will be definatly be getting those books you listed.
I like the idea of having the W18's being sealed in the enclosure for quality wise. I have the HK 3550hd reciver for my HT.

http://www.harmankardon.com/specifications.aspx?Region=USA&Country=US&Language=ENG&cat=REC&ser=&prod=AVR%203550HD&sType=

Will it be capable of running the cc enclosure to achieve frequencies in the lower 60's since it will be sealed?
All of my speakers including the tweeter are 8 ohms. Will the final result once the crossover is complete have a 8 ohm load to match my reciever's output?

[HareBrained]

You made a very common newbie mistake. You've selected the drivers before you knew what to do with them. Without the ability to measure the drivers and then the final system, you're going to have to work in the simulation domain.

It is possible to design a crossover if someone else measured a representative driver. There are other free tools that allow you to import the frequency response and impedance (digitized curves) and design the crossover. You'll need Response Modeler and Passive Crossover Designer from Jeff B (http://audio.claub.net/software/jbagby.html). Because this is a process, and certain things have to happen in a certain order, you should take an existing design and model it. You'll find that the predicted response can be very close to the measured system response. I suggest you model Zaph Audio's ZMV5. I've done it and I know it come out very close.

Zaph Audio measured both a W18 and 1337. This data can be digitized using SPLTrace. He has not measured the 9800. You'll have to find that elsewhere or select a tweeter he has measured.

[Curt C]

I have the HK 3550hd reciver for my HT. Will it be capable of running the cc enclosure to achieve frequencies in the lower 60's since it will be sealed?
All of my speakers including the tweeter are 8 ohms. Will the final result once the crossover is complete have a 8 ohm load to match my reciever's output?

If you run the center w/o any high pass filter it will have its expected f3 in the low 60's, and a 2nd order roll off. Applying a hp filter of 80 Hz for instance will result in a 4th order roll off at 90 Hz.

The 2 W18's in parallel will present a 4 ohm impedance through their passband. I'd consider this a 4 ohm design.

C

[Pat.M]

Thanks for all the info guys.
I decided to go ported for the two woofers in my enclosure. In this case is it a good or bad idea to have the mid and tweeter in the same open volume of the woofers or should I make a seperate chamber in the center to conseal them alone? If so should it be ported or sealed?