no ferrofluid in poly dome tweeter?

printboy

I purchased a replacement tweeter for my Monitor 4As as advertised as a replacement on
ebay earlier this year. The tweeter with the phase plug. Its the only drop in replacement I have ever seen that exactly fits the square recess on the speaker baffle. The cost was minimal so I took a chance. Doesnt sound bad and has a more open top end than the original tweeter.

For fun I removed the dome/voice coil/flange from the magnet and discovered that there is no ferrofluid used in this tweeter. Not even a trace on the voice coil or in the circular gap in the magnet where the coil fits. Its bone dry.

I contacted the seller and he told me if thats how it was issued by the manufacturer then they know best and not to do anything. What are your thoughts on this and think it would be best to add ferrofluid for the tweeter to sound and operate at its best?

printboy

Thank you.

F1nut

Phase plug? That's just a piece to protect the tweeter, which never had ferro fluid.

printboy

Sorry I was just describing what the original tweeter and replacement tweeter look like regarding the phase plug for reference purposes. I believe the original Monitor 4A tweeter is the RD0202-1. The circular channel in the magnet part of the tweeter where the voice coil fits there is no fluid in the replacement. But there is fluid in the original tweeter.

For some reason I am having difficulty in attaching photos to my post. File keeps failing to upload. The design looks the same as compared to the stock tweeter. But not trace of ferrofluid on the replacement tweeter.

F1nut

Oh really, hmmmm......I was pretty sure they didn't have ferrofluid.

printboy

Thanks for responding F1.
Yes the square bezel 4A tweeter, mine which was produced in Taiwan, has ferrofluid. I saw it on the voice coil and in the channel in the magnet.
Guy I bought the replacement tweeter from said it is Japanese made by Tonegen but there are no markings not even for ohms. He said it was far superior to the stock 4A tweeters. I asked him how he knew all this and he responded by saying, well after awhile being involved in audio for 50 or so years one gets to know these things.
ahhhh yeah!
Now I can post photos for some reason of the replacement tweeter.
Excuse my lack of knowledge but are some tweeters like this designed not to have ferrofluid?

F1nut

That is not a 4A tweeter.

Nightfall

The plastic on the front is a little different but everything else does look similar.

printboy

It was advertised and sold as an improved drop in replacement for monitor 4A. Fits perfectly.

Just want to know if I should just leave it as is or would adding ferrofluid possibly improve SQ and performance of the tweeter?

Thanks

Nightfall

I wouldn't mess with them if they're designed to be air cooled. Adding ferrofluid will change the properties of the tweeter including impedance and frequency response.

https://stason.org/TULARC/entertainment/audio/general/12-17-What-are-fluid-filled-fluid-cooled-ferro-fluid-twee.html

The other big effect of this fluid is to add
mechanical damping. The frequency response and transient
response of the driver will change.

It is very risky to blindly add fluid to a driver. It may not
be compatible with the adhesives used in the driver, may not be
practical with the particular driver layout, and is impossible
to remove. Permanent driver damage is possible.

F1nut

printboy wrote: »

It was advertised and sold as an improved drop in replacement for monitor 4A. Fits perfectly.

Just want to know if I should just leave it as is or would adding ferrofluid possibly improve SQ and performance of the tweeter?

Thanks

That doesn't mean it's so. You said the replacement sounds different, which doesn't mean it's an improvement, just different. Either buy a used Polk tweeter or buy another replacement tweeter, so the speakers match. If it was me I'd look for an original.