Question about the 2225H

[pangea]

The other day I replaced one of my 2225's and I immediately noticed the severe stiffness of the cone.

Is that normal with the 2225?
The suspensions on my newly reconed 2220A's are softer, so I'm thinking if it's possible that the fabric surrounds can dry up and stiffen that much?
If so, is it possible to soften up the surrounds again somehow, or do I have to have them replaced?

BR
Roland

[GordonW]

A new 2225 should be pretty stiff. They will loosen up upon use.

The 2225 has a heavier cone and a stiffer surround in general, than the 2220. So, it's normal for it to be stiffer, by a moderate amount.

Regards,
Gordon.

[pangea]

OK, thanks for the info!

Well, they have been at work for some time now, but they have never been driven hard. So, perhaps I shoud give them a bit more than the mW's they usually have to take.

Perhaps I should let them perform at a few parties now and then, at least feeding them with a few watts or more.
You think that'll soften them up a bit and perhaps lower the fs?

BR
Roland

[jbl]

My 2225's took quite a while to break in. Are your cones original or after market? They should be paper not material.

Ron

[pangea]

My 2225's took quite a while to break in. Are your cones original or after market? They should be paper not material.

Ron

Hmmm...The surrounds are definitely made of some sort of very stiff and almost rigid fabric, that looks somewhat like the surrounds of the 2123's, but are much stiffer though.

Does this mean they have been reconed?

If so, is there anything available out there, which could soften up the surrounds somewhat?

BR
Roland

[jbl]

They should have a somewhat wet look to the outside of the driver. Almost a tacky feel. Could you post some pictures?

Ron

[pangea]

They should have a somewhat wet look to the outside of the driver. Almost a tacky feel. Could you post some pictures?

Ron

There is no "wet" look and the surface is absolutely dry and quite hard.






BR
Roland

[Mr. Widget]

That looks about right... how stiff? Is it noticeably stiffer than your other 2225? I would assume the surround should be identical to your 2220 surrounds.

By stiff do you mean the entire suspension, i.e. the surround and spider together, or are you pushing in on just the surround?


Widget

[pangea]

That looks about right... how stiff? Is it noticeably stiffer than your other 2225? I would assume the surround should be identical to your 2220 surrounds.

By stiff do you mean the entire suspension, i.e. the surround and spider together, or are you pushing in on just the surround?


Widget

The surround on both 2225's are equally stiff, but they are both significantly stiffer than the surrounds of the 2220's, which both are newly reconed by an authorized reconer.

Unfortunately I don't know anything about the history of the 2225's.

I would say however that most of the the stiffness comes from the surrounds, though I can't exclude that the spider is also adding to the stiffness of the entire (2225) cone, to some extent.

BR
Roland

[Mr. Widget]

I just looked up the TS parameters... the 2225H has a free air resonance of 40 Hz! (I assumed it was like the 2205A at 30Hz) with a cone weighing 105g, the 2220A/H has a free air resonance of 37Hz with only 70g. Based on that I would expect the 2225H to be significantly stiffer.

Do you have an audio oscillator and ohm meter to measure the free air resonance?


Widget

[pangea]

I just looked up the TS parameters... the 2225H has a free air resonance of 40 Hz! (I assumed it was like the 2205A at 30Hz) with a cone weighing 105g, the 2220A/H has a free air resonance of 37Hz with only 70g. Based on that I would expect the 2225H to be significantly stiffer.

Do you have an audio oscillator and ohm meter to measure the free air resonance?


Widget

I've got the Ohm-meter and I probably have a tone generator in the computer, but I'm still not sure how to measure.
Would it be OK to have the woofer mounted in the baffle if the back of the box is open, or does the woofer have to be suspended in mid air, hanging in a thread?
If so, then what do I do?

BR
Roland

[Mr. Widget]

You must hold the woofer out of the cabinet in free air.

Here is a site that describes the process. It is really straightforward.

http://sound.westhost.com/tsp.htm


Widget

[pangea]

You must hold the woofer out of the cabinet in free air.

Here is a site that describes the process. It is really straightforward.

http://sound.westhost.com/tsp.htm


Widget

Many thanks, I'll check it out tomorrow, it's a bit too late for that right now.

BR
Roland

[Earl K]

Hi Roland

I must own around 20-30 odd 2225 woofs and a hand-full of 2226(s).

It's a stiff-ribbed cone with a very stiff compliance which can make it seem almost "stuck" or "seized" ( compared to anything with an Fs of around 20 hz ) . That 2220 has such a "flimsy" cone in comparison - that it'll give you a misleading reference point ( even though it's Fs is similar at around 37hz ).

It is hard to believe that a 2225 has a 40hz Fs, when you first feel it .

I happen to have a couple at home. I'll post some pics tomorrow. One is a recone that's 21 years old. I've recently measured its' Fs at @ 40.5 hz .

FWIW: The surrounds are not a simple extension of the paper-cone / they are a double-roll of treated fabric ( assumed by me to be glued on ). I think this surround type was first introduced around 1972-3 - see "PRO-NOTE" Volume 1, Issue 3 -7 ( for some time references ).

Ooops - those "PRO-NOTES" are not yet in the "Library" .

[Mr. Widget]

Ooops - those "PRO-NOTES" are not yet in the "Library" .

Widget