$3 1" dome tweeter.

[biscuitbarrell]

Re: $3 1" dome tweeter.

Cabrini MKII uses a different woofer. I have a design using the MCM woofer and the MCM tweeter, just gotta get the info together in one place.

So it does! I'm looking forward to that MCM design.;)

[dlr]

Re: $3 1" dome tweeter.

Considering the limited room to work with, Dave, do you have any recommendations for something to stick behind that dome?

I am not over concerned about it, it is just academic curiosity

You can buy self-stick cotton and cut it to fit, but by the time you spend money on that (probably have to order it online), just buy a better tweeter. If you have something on hand or similar, it won't hurt to test it, since it will be reversible as long as you take car with the dome when doing this.

One thing I would try, because I have it, is some cotton I removed from an old printer years ago. Cotton has been used at times to damp vibrations in some of them. I wouldn't spend any real money on this unless you just want to experiment. I've done that a lot and have a lot of tweeter parts lying all around on my shelves. :eek:

dlr

[PWR RYD]

Re: $3 1" dome tweeter.

Interesting thread guys. I have only taken one tweeter apart, a Dynaudio D-28/2 that I bought back in 1992. It was constructed exactly as dlr descibed the SS tweeters. It had a medium density cotton plug right behind the silk dome (with the same profile as the dome), a vented pole piece and a rear chamber that was stuffed with yellow fiberglass. It also had ferrofluid.

[johnnyrichards]

Re: $3 1" dome tweeter.

Considering the limited room to work with, Dave, do you have any recommendations for something to stick behind that dome?

I am not over concerned about it, it is just academic curiosity

[dlr]

Re: $3 1" dome tweeter.

Ferro-fluid in the gap makes drilling an even riskier venture. I have some felt furniture feet that I planned on trying.

That is probably more reflective than absorptive, but even so it may make an improvement. The dip probably won't be as deep. It may also be spread in a way that would allow for some equalization. The positive aspect of EQ of this problem is that it helps in the polar (off-axis) response as well since these resonances are usually also seen to be similar in the polar response, contrary to baffle diffraction that changes. EQ can be more effective here.

What you'll need to be very careful about is trimming the edges to ensure that there is no contact with the dome.

dlr

[johnnyrichards]

Re: $3 1" dome tweeter.

Cabrini MKII uses a different woofer. I have a design using the MCM woofer and the MCM tweeter, just gotta get the info together in one place.

Yes, very nice midrange out of this $5 woofer, though.

[biscuitbarrell]

Re: $3 1" dome tweeter.

Biscuit - I have a design close to ready using those MCM drivers. We should compare notes

I doubt if my notes have anything to offer you, as I'm VERY new to this hobby! I'll offer my impressions thus far FWIW; I started with the mcm drivers in a .63cu.ft. vented box, ( 2-inch dia. x 7-inch length, flared one end ) lined with half-inch, high-density carpet underlayment foam. I was liking the sound; better than expected bass from a 6.5-inch cheap driver, but was able to get a bit of 'flabbiness' at very high volumes. These volumes were higher than I'd normally play, but still I didn't want it there. Sealing the vent took care of it, and I didn't lose as much of the bass as I thought I might, but of course there was SOME loss. The bass that remains is quite punchy. I really dig sealed bass sound!
The mids in these are very clear on vocals, and I'd like to try a 3-way tower with the 6.5 pulling midrange duty. Standout vocals I noticed were Norah Jones, Janiva Magness, Diana Krall, Alison Krauss, Kathleen Edwards, Warren Zevon, and Johnny Cash. Good rockin' thump listening to John Fogerty's "Blue Moon Swamp", Collective Soul's "Youth", The Refreshments' "Fizzy Fuzzy Big and Buzzy", Mike Ness's "Cheating at Solitaire", and a little Jackson Brown, "Redneck Friend".
Norah Jones in particular sounded "in the room" with me. (A happy thought!)
Since I knew I'd be running these with a passive sub, I thought I'd see how small a box would still remain practical. I modeled in BassBox6 and came up with a box 6x12x8, for a whopping .33 cu.ft.! This models an f3 of about 75 and f10 of around 45. They are very listenable, even without the sub, at low levels. As configured, should cross easily at 80Hz to any sub.
I've been looking at your Cabrini MKII XO, and comparing it to mine. Mine is way different! ( i.e. amateurish) I was working with a limited amount of material and budget, and you know- "when the only tool you have is a hammer, all problems begin to look like nails." But they are listenable, not bad at all!

[johnnyrichards]

Re: $3 1" dome tweeter.

Bummer. It would be hard to justify taking a drill press to it even it it wouldn't be too difficult. Maybe one of those self adhesive felt pads for chair legs would help?

All of the cheap tweeters I've taken apart had something behind the dome. Even an AR 2" dome mid, which had a dome shaped wooden slug glued to the pole.

Thanks for looking in to that.

Zach

Ferro-fluid in the gap makes drilling an even riskier venture. I have some felt furniture feet that I planned on trying.

[Zach C.]

Re: $3 1" dome tweeter.

It appears rear chamber mods will be more trouble than it is worth, however - there does appear to be hope for possibly throwing a small wad of polyfil or something directly behind the dome as there is currently nothing there, and many of the tweeters I took apart seem to have something behind the dome.

Bummer. It would be hard to justify taking a drill press to it even it it wouldn't be too difficult. Maybe one of those self adhesive felt pads for chair legs would help?

All of the cheap tweeters I've taken apart had something behind the dome. Even an AR 2" dome mid, which had a dome shaped wooden slug glued to the pole.

Thanks for looking in to that.

Zach

[domwilson]

Re: $3 1" dome tweeter.

This may sound gross, I've wondered if lint from the lint trap of a drier would make a difference.

[dlr]

Re: $3 1" dome tweeter.

It's not what I had thought, I figured that there was at least a pole-piece vent opening. The distance from dome tip to top plate must be close to 1/2".

A soft wad of cotton won't be nearly enough. That one is much like many (very) old tweeters. The better ones had a hard cotton near-hemispherically shaped piece glued to the top plate that left a small gap between that dome and the diaphragm. This eliminates most of the lower and mid frequency resonances and is somewhat absorptive of higher ones. It's not ideal, but with a solid top plate there's not much else you could do. Some of them also had a foam dome rather than hard cotton, but that's much less effective, especially at lower frequencies.

Interestingly, drivers like the Scan-Speak 9300, 9500 and 9700 all have a hard cotton (?) plug over a real vent to a real chamber and the top part is shaped to somewhat match the shape of the dome. This still allows for low end output due to the much larger effective volume.

Whatever you may try, be very sure that nothing can get into the voice coil gap and size it to prevent any dome contact.

dlr

[johnnyrichards]

Re: $3 1" dome tweeter.

The faceplate is a separate piece of plastic that is very easily removable. Beneath that is a secondary piece of plastic removable by taking out four screws. That holds the VC assembly in place.

Removing the VC assembly exposes a a solid slug:


It appears rear chamber mods will be more trouble than it is worth, however - there does appear to be hope for possibly throwing a small wad of polyfil or something directly behind the dome as there is currently nothing there, and many of the tweeters I took apart seem to have something behind the dome.

[Zach C.]

Re: $3 1" dome tweeter.

Why yes, it does appear to be openable.

Interesting.

Thanks

[johnnyrichards]

Re: $3 1" dome tweeter.

Johnny,

Does it look like these can be opened up for mods?

Pics sure don't look like it. If I ever ordered from mcm, I'd just give it a try, but I couldn't tell you the last time I needed anything from them.

Why yes, it does appear to be openable.

[Zach C.]

Re: $3 1" dome tweeter.

Johnny,

Does it look like these can be opened up for mods?

Pics sure don't look like it. If I ever ordered from mcm, I'd just give it a try, but I couldn't tell you the last time I needed anything from them.