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Infinity Interlude IL40 8" woofer TS specs
So I bought a pair of these from Fleabay for around $65 shipped, which is a good price for any 8" woofer these days.
Deep drawn stamped basket, plenty of mechanical throw, doesn't bottom out when pressing all the way down on the cone, bumped and vented back plate, 8mm top plate.
Not unattractive to my eyes - although I have always liked how the Infinity CMMD drivers looked, not too mention these are from what I call the "golden age" of Infinity (The early 2000s). Loved how their products looked and performed from that period.
Nice modeling driver (with 0.8 ohms series resistance added - simulating what a 3-way crossover would add)
Also bought the matching 4" midrange/midbass drivers so could make a pretty cool Interlude IL40 tribute build.
Comments
They want stupid money for any actual CMMD tweeters, likely because they are what blows on these things. So I would substitute a Dayton since it is a small waveguided unit like the Infinities all used back in the day.
Anyways, interesting drivers with some interesting design possibilities.
Those look nice, not just the look but the specs as well. What’s the modeling look like with a tad lower tuning freq ( ie addressing the slight bump @ 40Hz ?
You should check the division I use on my scale - that "bump" is a quarter of a db. I will buy a steak dinner to anyone who can pick out a 1/4 db in that range
In all seriousness this is a good example of how relatively inexpensive commercial speakers do not all use crap drivers like we want them to.
Any plans to rear mount or fab some trim rings?
I might do so. I currently only have dreams about these, though. Might go in to the museum along with all my Rat Shack stuff.
Those woofers do have nice parameters. Seeing that Fs down in the 20's is always a good starting point.
Sehlin Sound Solutions
And the midrange. Will deo 71Hz in 0.1 cubic feet, although no idea how to port that bad boy lol.
In 0.05 cubic feet it has an F3 of 150Hz and a Q of 0.7 - should make for a fine midrange driver.
I am thinking of moving forward with doing a project with these.
Using the Fountek knockoff ribbon for the top end.
Yeah, something similar to the EMIT tweet they used.
Looks like the EMIT were planar style with traces. I wonder how much the FR would get messed up if someone were to make an EMIT style faceplate for these..
https://www.parts-express.com/Dayton-Audio-PTMini-6-Planar-Tweeter-6-Ohm-275-083?quantity=1
Someone here (John Hollander maybe?) measured those PTMini's and said they were unusable below 6k due to distortion.
^^I've got a pair of old EMIT tweeters, and I can say the same about them. Super-tweeters at best, they are bigger than the PTmini however.
Yes I measured them. 6K sounds right. They look cool and have a bit of sparkle. I had some quality issues with wrinkled membranes that made them annoying to look at.
These are off to Brad for some iec measurements. See how they perform.
Nice little midrange. 4”mid.
Distortion 0.5m
FR 0,15,30,45,60,75 degs.![]
The 8” woofer.
Distortion 0.5m
FR 0,15,30,45,60 deg.
Both drivers were pretty quiet during testing which is something I really pay attention to lately.
Not too shabby! JR can certainly work his magic with those!
Dang those beat the pants off most budget stuff. 45+db down from 120hz to near 3khz on the 4"? Pretty much cover your eyes and pick your xo point to the 8" too within reason. Looks like it should make for a refreshingly laid back design experience.
I've been staring at his graphs of the 1204 in visaton waveguide too long... But seems the polars would line up beautifully around 2-2.5khz to that 4". You know what they say.. with a hammer in your hand, everything starts looking like a nail.
Guess I will be doing something with these for sure. I am generally impressed with them - Infinity really leveraged Harman's R&D capacity when they were doing all their CMMD stuff starting in early 2000s.
Looks like the 4" will just barely reach to the ribbon, as well. Should be close to CD up to 30 degrees off-axis.
Bet this turns out really well, off to AutoCAD for some cabinet design!
Looks like the Interlude 12" subwoofer drivers list for around $80 on Fleabay... hmm...
Here's some "hard data" if anyone is interested about these old EMIT tweeters. If anyone asked me, I'd say these tweeters are shot, but I don't think that's the case, I think they're just crap.
Mounted in a bookshelf size speaker for testing. FR is awful, with a big hole where the treble should be.
Raw measured response to 90 deg, at 15 deg increments. As expected, Horizontal dispersion is wide.
For a estimation of infinite baffle response, I divided the on-axis by the diffraction simulation. The majority of baffle influence occurs <3kHz where this tweeter has next to no output, so a positive note is that it's fairly unaffected by baffle placement.
For distortion, I tested the raw response at 2.8V from 800Hz up, keep in mind that SPL here is not calibrated. I also tested with EQ to hammer the response to 4kHz LR4 and LR8 targets. Raw response and EQ response below.
Distortion at 2.8V. Yikes!
Testing again with an EQ for 4kHz LR4:
Testing again with an EQ for 4kHz LR8:
If it were me, I'd start rolling off this tweeter at 8kHz, in which case I'd ask myself "what's the point?". It's a super tweeter for "sparkle" only.
For a point of reference, here's a Scan-Speak R2604/8330 ring radiator on the same baffle, same 2.8V measurement with the same gear.
If that tweeter isn't bad, it's terrible. I don't think I've ever heard them before. Thanks for the data.
I'll be starting a thread dedicated to a build using these. I think they are good enough to use.
@dcibel R2604/8330 is really a gem in the rough. Overachiever.
I've been looking hard to find something better, at any price.
Here's a whopper, you'll never guess what it is. I'm trying to work through testing of all my drivers on the shelf over xmas break, maybe I'll have some semi-useful comparisons to share once I'm through them all. Some surprises for sure in my collection, this is one of them.
My other R2604 didn't test as well as the first, but still good.
Sorry, OT.