What's the latest best x-over for GPA 604-8III

[drummerwill]

I had my DIY Jeff Markart designed 604-8K cross over for some time now and was getting bored with the sound of the speaker.

After cranking the HF L-pad all the way up. I decided to bypass the L-pad all together. I like that much better. I built my cross over about
4 years ago, I'm wondering has anyone came up with a simpler designed 1200hz x-over. Something maybe a little more elegant ,maybe lesser part count.

Thanks

Willie

[bowtie427ss]

Active.

Honestly, no experience here with the GPA stock.

I went active with my 8G's a few years ago, and now with the PAS duplexes, i'm not looking back.

My next crossover horizon is going to be mini DSP. Depending on what you have on hand for amplifiers, a DSP solution can nearly challenge the economics of a passive solution these days.

[Twodawgz]

I also went active with my 604E's several years ago with a unit from these guys:
electronic crossover, active crossover, discrete opamp, custom amplifier, passive preamp

By far the best upgrade I ever made to my system in 35 years.

[gortnipper]

I have only heard two with my GPA 604-III - the stock N604-8A and a custom one made by Rick Craig at Selah Audio. Rick's is much, much nicer - very smooth and not nearly as much "shout". I am very happy with it, even with basic "stock" parts. I have talked to several other 604-III buyers who have also bought Rick's xo, and are very happy with it.

From Rick:

"I didn't really pay any attention to the stock crossover or specifications when creating the new design. The drivers were tested for frequency response and impedance and then everything was imported into our software optimization program.

This combination presents a difficult challenge in that there's very little overlap of the driver response curves due to the fairly small horn and large diameter woofer. The woofer has a significant breakup in the 1.8K-3K area The tweeter also has resonance issues in the 1-2K area. The shaping of the filters around the crossover point is critical and choosing the place to cross isn't easy.

I started first with a lower parts count crossover and experimented with different topologies. The objectives were to maintain good phase response in the crossover region, minimize the resonance and frequency response issues, maximize horizontal dispersion coverage, and provide plenty of headroom to keep the horn distortion low.

The crossover's acoustic slope target around the crossover point was 24db/octave. There are different ways to achieve this and a third order electrical filter was implemented for the tweeter. The woofer filter is a first order combined with a parallel resonance trap. Both are far from textbook values and designed to work in tandem with the driver responses to achieve the desired acoustical transfer function.

I also added a conjugate filter which creates a smooth system impedance. This is important for tube amps, in particular SET designs which typically have high output impedances. The less reactive load will provide better results and insures compatibility with virtually any tube amp."

I also know of a couple of people who have used Werner's mast_mutter | eBay xo's with several different Altec related projects, including 604-IIs and the WVL 604 field coils based on the GPA 604-III and they were all well pleased with it, but I have not heard those systems.

[Steve M]

bowtie427ss, which brand and model of active crossover are you using at the moment on your 8G's, may I ask?

Active.

Honestly, no experience here with the GPA stock.

I went active with my 8G's a few years ago, and now with the PAS duplexes, i'm not looking back.

My next crossover horizon is going to be mini DSP. Depending on what you have on hand for amplifiers, a DSP solution can nearly challenge the economics of a passive solution these days.