Dayton RS180 / Seas 27TBFC 2-way Bookshelf Project

[Jay_WJ]

I'm a biginning DIYer and want to start my first (hopefully last, but I know it's addictive ) speaker building project. I appreciate any helpful comments.

The design goal is to build an excellent cost-to-performance 2-way bookshelf for HT/music use with a subwoofer added. For drivers, I chose Dayton RS180S-8 metal cone woofer and Seas 27TBFC/G metal dome tweeter, based on their excellent distortion measures reported in DIY circles.

I'm currently in a simulation stage using FRD Consortium tools and Speaker Workshop. Unfortunately, I don't have a measurement setup yet and won't be bothered to have one for this project---I know it's reckless but that's what I can afford at this time.

For consistent measurements between the woofer and tweeter, I used the same Zaph's data for them---measured on an infinite baffle using the same method and tools.

Using FRC tools, I simulated the frequency responses of measure box and baffle, and target box and baffle. And they were combined to obtain a frequency response to be used in Speaker Workshop for XO design. I found FRC tools very sophisticated---how much sophisticated? I'm not an expert, so I'm not sure, though---and easy to use.

I'll use PE .5 cu 2-way cabinet for vented design with a port tuned at 47Hz.

Using Speaker Workshop, I came up with two different XO designs. Actually, I benchmarked two existing network topologies for metal cones. One is Zaph's L18/TBFC and the other is Roman JB's modified Dr. K RS180/RS28 MTM design. After a lot of tweaking trials, I decided on two XOs (see attached figures). Their resulting frequency responses with individual driver responses are also attached.

As you can see, their FRs are virtually identical. The crossover point occurs at around 1.66k. Their impedance plots are also virtually identical with minimum 5 ohms around 3.5k (figures not attached).

A key difference between the two designs is the type of a notch filter used to attenuate the cone breakup peaks of RS180. The first one uses two series LC notch filters parellel with the driver (Zaph's L18 design bechmarked) and the second uses a parallel notch serial to the driver (RJB's RS180 design benchmarked).

A minor difference in their performance is their modeled reverse nulls when the tweeter polarity is flipped (figures attached). Design 2's reverse null is deeper that Design 1's.

My question is, which XO design is better? If you prefer one to the other, why?

[Jay_WJ]

XO design 2

[Jay_WJ]

Design 1 Frequency Response

[Jay_WJ]

Design 2 Frequency Response

[Jay_WJ]

Design 1 Reverse Null

[Jay_WJ]

Design 2 Reverse Null

[Jay_WJ]

Sorry for the multiple posts. My website doesn't work for now

[Jay_WJ]

My website works now. So I started a new thread here:
Simulation Results: Dayton RS180 / Seas 27TBFC 2-way Bookshelf

I'd appreciate any help.