Introducing the Starfire

[JasonP]

Expect a lot more to come in this thread, but the design is very promising (initial measurements look great):


Starfire - Early - Ugly by JasonP75, on Flickr

That is the RS28F and RS100P-8 in front, modded using ModerMasters metallics for effect, and a HiVi M8A on the bottom side without mods. This is all in a knockdown tower box from PE (300-7066), I could not pass them up at the sale price of 55$. I'm thinking the box finish will be some kind of distressed steel effect or something, time will tell.

The side firing M8A close to the wall is flat, needing no baffle step at all. Nice. There is some ripple, +/- 2db in its range, but that isn't any worse than room modes normally anyway (likely better than most).

I'll keep this thread updated as I progress!

[Paul Carmody]

Re: Introducing the Starfire

Something different and bold. I like it!

[lowpolyjoe]

Re: Introducing the Starfire

Cool! First design to hit the street using the Rs paper line?
And they were just dotd too...

[jsr]

Re: Introducing the Starfire

Looks cool. What frequency are you crossing the M8 to the RS100Ps? I was thinking of something like that too to avoid needing multiple smaller drivers on the front baffle.

[JasonP]

Re: Introducing the Starfire

Building the prototype XO now, here is the measured drivers in the PCD model. Its all 2nd order, LR2 on the tweeter/mid at 3khz has me leaning the speaker back 8 degrees to get the phase right. Not unexpected though, and it looks kind of neat leaning back a bit Does this XO qualify as minimum phase? I'm not sure how that is judged. The mid/tweeter share perfect phase alignment an octave up and down. Hmmm.


Starfire Test XO 1 by JasonP75, on Flickr

The grey overlay is the midrange reversed.

Also, I suppose based on the naming the speaker is female and has a mascot!



*chuckle*

[JasonP]

Re: Introducing the Starfire

Looks cool. What frequency are you crossing the M8 to the RS100Ps? I was thinking of something like that too to avoid needing multiple smaller drivers on the front baffle.

I think my last post indirectly answered that: just below 300 Hz. Still subject to initial listening tests mind you!

[Wolf]

Re: Introducing the Starfire

Where's the ports?
That is an ideal box size for the M8 if you use the whole box and tune to around 30 Hz with a pair of 2" ports.

I'm with Paul- I like it!

Mind you- the M8 is some of the best bass I've heard from an 8" driver.
Later,
Wolf

[Whitneyville1]

Re: Introducing the Starfire

If I followed his photos correctly, it looked like about a 3" port at the top back tuned to ~38Hz by the impedance dip. A quick-n-dirty in WinISD says that can work (elbow?) If I looked at the wrong photo, well, you'll just have to kill me.

[JasonP]

Re: Introducing the Starfire

If I followed his photos correctly, it looked like about a 3" port at the top back tuned to ~38Hz by the impedance dip. A quick-n-dirty in WinISD says that can work (elbow?) If I looked at the wrong photo, well, you'll just have to kill me.

Well you are mostly right. The port is 2.75" diameter, just below the middle on the back, 5.25" long, part number 260-410. It is tuned to just below 40 hz.

The box is actually too small for the measured M8A, which measures way off its spec (Qts much higher), but with 1 cubic foot of acoustic-stuf that seems to be mitigated ok.

[JasonP]

Re: Introducing the Starfire

That is an ideal box size for the M8 if you use the whole box and tune to around 30 Hz with a pair of 2" ports.

I'm with Paul- I like it!

Mind you- the M8 is some of the best bass I've heard from an 8" driver.
Later,
Wolf

The whole box, stuffed with 1 cubic foot of acousta-stuff as I mentioned above, with a 2.75" port tuned to just under 40 Hz.

Yes, the M8A has great bass. I didn't know what to expect going in, but honestly with the floor boost I moved them out from the back wall. There was actually too much bass close to the rear wall, and it was nice for a change I originally planned on using the RS225-8 for an all Dayton design, now I feel glad I saved the twenty spot and picked these. I won't lie though, the choice was cosmetic. These HiVi cones are damn sexy!

[[email protected]]

Re: Introducing the Starfire

Pretty cool Jason.

[BOBinGA]

Re: Introducing the Starfire

Those are intriguing. You might experiment with a 150hz crossover. The lower you can take it, the better. In my view, the more midrange from a single speaker you can get safely, the better, especially with the woofer mounted that far away.

-Bob

[Wolf]

Re: Introducing the Starfire

Well you are mostly right. The port is 2.75" diameter, just below the middle on the back, 5.25" long, part number 260-410. It is tuned to just below 40 hz.

The box is actually too small for the measured M8A, which measures way off its spec (Qts much higher), but with 1 cubic foot of acoustic-stuf that seems to be mitigated ok.

I used 32 ltrs for mine. Lining and a good wad.
Later,
Wolf

[JasonP]

Re: Introducing the Starfire

Inital XO now under listening tests, smooth smooth smooth. Maybe too smooth? Its hard to point out anything wrong when listening though... wow, nicely played PCD. The initial XO may be the final! Measurements:


Starfire Test XO 1 measure near wall 24 inch 90db by JasonP75, on Flickr

That was still almost on the back wall, since then I've moved them out a foot more and they sound much less heavy. Can't recall the last time I had too much bass...

[50 watt head]

Re: Introducing the Starfire

Very cool, Jason. I've been lately thinking of trying a 3-way with the RS100P as a mid, and your results are all the more encouraging. Looking forward to seeing your xover specs.