Tuning the Natalie P's (RS180-RS28) after building them

[mslatter]

I built Jon Marsh's Natalie P's (RS180-RS28 MTMs in a 9x22" baffle sealed cab) a few years ago after looking for a good mid-price project. I've been really pleased with them. I like the clarity and detail of the combination, and it was a pretty simple build with a series cross-over. They've been my workout speakers in my bedroom for a while now.

I've moved them into a different room and set up a bit more of a traditional listening position for them about 8 feet away, and now that I'm spending a little more detailed time with them, I hear a little harshness that I'd like to tweak out. I hear it primarily in electric guitars and saxophones. Voices sounds great, and other instruments are fine but with a little bit of volume behind it, the guitar and sax grates on me a hair, and I turn the volume down. In the past, when I've tuned car stereos, I've attenuated around 6kHz, if I recall, based on personal preference, but don't hold me to that.

So, the question is whether there's something I can do, short of getting an equalizer, to try to reduce the little bit of harshness I hear? Here's Roman B's comparison of the predicted frequency response curves for various cross-over designs with that speaker combination, by the way. http://www.rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

Thanks in advance for the help!

[jonasz]

Re: Tuning the Natalie P's (RS180-RS28) after building them

Ask the designer himself over at htguide forum.

[Chris Roemer]

Re: Tuning the Natalie P's (RS180-RS28) after building them

If I knew which "band" you wanted to passively lower (and by how much), I could take a run at it.

[donradick]

Re: Tuning the Natalie P's (RS180-RS28) after building them

Sorry to bring this up, but you mention Roman Bednarek.
Even he said that he developed a couple of different crossovers that sounded (and measured IIRC)
better than the stock Natalie P crossover.

If you are willing to spend a bit of money, I'd strongly suggest using the Jeff Bagby RS180 MTM crossover.
Simple and smooth.
http://techtalk.parts-express.com/sh...ighlight=rs180

[speedle]

Re: Tuning the Natalie P's (RS180-RS28) after building them

I may be mistaken, but I believe he was referring to the stock PE kit crossover, not the Natalie P one. It's been awhile since I looked at that site though. IT would be really cool to see that comparo updated with a couple new crossovers in the mix.

[rpb]

Re: Tuning the Natalie P's (RS180-RS28) after building them

You might consider improving the damping of the box. Now I don't have a clue what you used, but some stiff fiberglass would be a necessity for anything I build. One inch on about 70% of the walls would be a good start. And, I'd place a piece between the two woofers, notched for the tweeter if need be.

[fastbike1]

Re: Tuning the Natalie P's (RS180-RS28) after building them

Nope, NatP was one of the XOs

I may be mistaken, but I believe he was referring to the stock PE kit crossover, not the Natalie P one. It's been awhile since I looked at that site though. IT would be really cool to see that comparo updated with a couple new crossovers in the mix.

[mslatter]

Re: Tuning the Natalie P's (RS180-RS28) after building them

You might consider improving the damping of the box. Now I don't have a clue what you used, but some stiff fiberglass would be a necessity for anything I build. One inch on about 70% of the walls would be a good start. And, I'd place a piece between the two woofers, notched for the tweeter if need be.

It's been awhile, but I don't think I dampened with anything more than a good stuffing of polyfill. I could always add more or different types. I've always considered damping to be more of a woofer-tuning thing, though, that adds resistance to the air cushion behind the cone. I've been thinking the harshness I get from the speakers is more in the tweeter, though. Would changing the damping help with the issue I've identified, or is it just more a general suggestion for this combo of drivers?

For those that suggested new crossovers, I'll take a look! The rjbaudio comparison have a couple that take the tweeter down a hair from the Nat P's (which was Jon Marsh's original design, not a stock piece.) I did use decent quality components to build this cross-over back in the day, so I'd prefer perhaps to modify it to retain my investment. But I'll spend if that's the answer. Unfortunately, I don't know exactly what freq range I'd want to lower at this point. It'd be a best guess.

[rpb]

Re: Tuning the Natalie P's (RS180-RS28) after building them

It's been awhile, but I don't think I dampened with anything more than a good stuffing of polyfill. I could always add more or different types. I've always considered damping to be more of a woofer-tuning thing, though, that adds resistance to the air cushion behind the cone. I've been thinking the harshness I get from the speakers is more in the tweeter, though. Would changing the damping help with the issue I've identified, or is it just more a general suggestion for this combo of drivers?

For those that suggested new crossovers, I'll take a look! The rjbaudio comparison have a couple that take the tweeter down a hair from the Nat P's (which was Jon Marsh's original design, not a stock piece.) I did use decent quality components to build this cross-over back in the day, so I'd prefer perhaps to modify it to retain my investment. But I'll spend if that's the answer. Unfortunately, I don't know exactly what freq range I'd want to lower at this point. It'd be a best guess.

Your description of the problem sounds like it could be in the midrange, or lower treble range. Sound bouncing around inside the box can come back out through the cone. If you absorb most of it in the box, or at least reduce its level, you may hear an improvement.

[johnastockman]

Re: Tuning the Natalie P's (RS180-RS28) after building them

Jeff Bagby has one, and if you're looking for a smoother, less harsh experience, he definitely knows how to work up a XO properly. I've heard a few people talk about his efforts on that design, and they all say great things, with no issue of harshness in that particular range at elevated volumes. It would require a new XO build-up, but I'll have to compare the diagrams to see if any parts can be re-used. Let us know how it's coming along.


John A.

[speedle]

Re: Tuning the Natalie P's (RS180-RS28) after building them

Nope, NatP was one of the XOs

I know it'll sound like a fanboy beating a dead horse, but I know the Nat P's were one of the ones, and he (Roman) specifically refers to the Dr K version as being one that several others sound and measure better than.