Scan-Speek 4" for 49 cents?

[dlr]

Re: Relapse

The DAP Alex Plus Clear caulk has been an unqualified success as a damping compound for slits and surrounds. I have used it on surrounds for 5 years and on slits for 1 year so far with perfect results.

The Wet Look was not effective for slits.

That's interesting. I found the Wet Look good for surrounds, never tried making slits. I'll have to get some of the DAP caulk to test. It will be good if it's better for surrounds, too.

dlr

[jbruner]

Re: Relapse

The DAP Alex Plus Clear caulk has been an unqualified success as a damping compound for slits and surrounds. I have used it on surrounds for 5 years and on slits for 1 year so far with perfect results.

The Wet Look was not effective for slits.

[fatmarley]

Re: Relapse

There's a calculator here - LINK. I don't know how accurate it is though because it doesn't ask where you are adding the mass.

[dlr]

Re: Relapse

If the resonance problem is coming from the spider, perhaps adding a bead of damping compound to the edge of the cone where it meets the pole piece would help?. Got to be worth a try.

The one thing to keep in mind with damping at the cone/former junction is sensitivity. Damping of the surround seems to have almost no affect on that, but near the former it's all highly moving mass and causes a drop in sensitivity.

dlr

[dlr]

Re: Relapse

Nice job. I would not have expected to see so much change top end. The impedance indicates that the problem was indeed due more to resonances than to geometry of the cone. The off-axis response should also be smoother as a result.

dlr

[fatmarley]

Re: Relapse

Great work! It's funny but I was thinking about his thread today and just before reading this post I ordered some stuff to try damping the cone of some cheap full range drivers I have.

If the resonance problem is coming from the spider, perhaps adding a bead of damping compound to the edge of the cone where it meets the pole piece would help?. Got to be worth a try.

[jbruner]

Relapse

I was sitting here the other day and just picked up a TB W4-1320 that was on the desk and started cutting the cone. Don't let anyone tell you they are cured. Once an addict, always an addict.


The cut driver is very pleasant to listen to. I didn't want to unhook it to measure it because I was enjoying the music. The stock driver just sounds wrong. The W4-1320 will never be a good fullrange driver because of inherent problems in the top octave and a weak midbass, but this will make shallow slopes easy when used as a mid.

For bumps and wiggles... Red line is before, Blue is cut.


There was no significant change in non-linear distortion products, so that is not shown. Distortion in the mid and treble is generally quite low.

I managed to clean up the impedance curve, too, but read carefully...

There are 4 distinct problem areas with the stock driver. The 7k spike is the primary cone break-up and is easily killed with 4 slices. The secondary cone breakup at 4-5k was controlled with 4 more slices. The 1.6-2k area is a surround/cone edge resonance that is partially addressed by the factory, but I simply added more damping compound to the first 1/3 of the surround. The 630hz resonance is the spider, and I don't want to talk about that one, grrrr.

[dlr]

Re: Scan-Speek 4" for 49 cents?

Just found THIS and thought it belongs here.

I've never seen anyone do this to a speaker cone before, so thought some may find it interesting.

That's been done in various forms over the years. Dunlavy used large pieces of felt on some of his woofers.

dlr

[fatmarley]

Re: Scan-Speek 4" for 49 cents?

Just found THIS and thought it belongs here.

I've never seen anyone do this to a speaker cone before, so thought some may find it interesting.

[feyz]

Re: Scan-Speek 4" for 49 cents?

You cut up a pretty expensive driver there, feyz!

dlr

:D, it was long time ago, when I could afford such attempts now and then once in a while.

[dlr]

Re: Scan-Speek 4" for 49 cents?

I took a look back at the 12 M dustcap I had removed. I remembered wrong. The dust cap attachment glue is like hot glue and is clear. The cuts are filled with some different glue. And as DLR wrote, they are applied from behind, for cosmetic advantage. The cuts are also like DLR described, about 1 mm slots, not just cuts.

You cut up a pretty expensive driver there, feyz!

dlr

[feyz]

Re: Scan-Speek 4" for 49 cents?

From my experimentation with 12M, the glue for me looked like a kind of hot glue.

I took a look back at the 12 M dustcap I had removed. I remembered wrong. The dust cap attachment glue is like hot glue and is clear. The cuts are filled with some different glue. And as DLR wrote, they are applied from behind, for cosmetic advantage. The cuts are also like DLR described, about 1 mm slots, not just cuts.

[aaronm]

Re: Scan-Speek 4" for 49 cents?

Double post, sorry.

[aaronm]

Re: Scan-Speek 4" for 49 cents?

I would look into this:

http://www.ebay.com/itm/1-oz-Pro-Gra...item460ff7430e

I use it for shoes & speakers. It needs a couple days to fully cure.

[feyz]

Re: Scan-Speek 4" for 49 cents?

Thanks. I posted a note to him. The 15W is what I have for midrange in my 3-way. I'm going to have to keep my eye on them now. :(

Looking at his photo, I think it's fairly clear that the damping compound is pulling away from behind, leaving an opening in the cone. It doesn't appear to be a simple slice in the cone.

dlr

From my experimentation with 12M, the glue for me looked like a kind of hot glue.