Stromberg Carlson RF-475 Tweeter Diaphragm Replacement ??

[zoltm]

Hi fellow cohorts,

I have recently found another Stromberg Carlson RF-475 speaker to match with another one single unit I hunt down years ago.

Unfortunately, this one comes sounding OK to start with but a bit dull, I was hoping some run-in would improve things. Obviously, things do not improve much, upon opening up the tweeter chamber, I found that the tweeter diaphragm is damaged. Voice coil deformed and semi-detached from the phenolic diaphragm.

I am hoping to get some expert advice on possible "compatible" other brand diaphragm that I might use. I think the original Stromberg Carlson RF-475 replacement tweeter diaphragm would be rare as han teeth.

I did some basic measurement, of the whole diaphragm unit as follow,

1. Voice Coil : 1.5 inch
2. Diaphragm diameter in metal gasket: 2.3/4 inch
3. Impedence: Unknown
4. Power handling: 32W

Hopefully I can get some collective intelligence from the experts in this forum on how to revive this pair of Stromberg Carlson RF-475.

Thanks and regards.

Miko

 

[CopperWizard]

I've got an rf475 that doesn't get much play because the woofer section intermittently rubs. I'm hoping to one day fix it or get it looked at. The capacitor in these is unknown but there is one in there and could be your issue. There are pictures online if you dig enough..

 

[zoltm]

I've got an rf475 that doesn't get much play because the woofer section intermittently rubs. I'm hoping to one day fix it or get it looked at. The capacitor in these is unknown but there is one in there and could be your issue. There are pictures online if you dig enough.. View attachment 1915988View attachment 1915990

Thanks for jamming in. I do have those two photos. That was something I look at before I have enough confidence to break open the tweeter cover and access to the tweeter diaphragm and realising that the somewhat duller RF-475, is indeed having a damaged tweeter voice coil. It breaks my heart. I opened up the another one too and have a nice clean up on the slit, that one is performing admirably after the clean up.

 

[zoltm]

Just to give an idea how bad the damage is on the voice coil. I am surprised that it can still sound but just dull.

It looks like to me the tweeter diaphragm was previously repaired but may be a bit not so professionally.

 

[zoltm]

I've got an rf475 that doesn't get much play because the woofer section intermittently rubs. I'm hoping to one day fix it or get it looked at. The capacitor in these is unknown but there is one in there and could be your issue. There are pictures online if you dig enough.. View attachment 1915988View attachment 1915990

Regarding your woofer rubs, if I am in your position, I would try talking to Jason at Hempo. I hook up with him at eaby seeing a posting of him. It was a reddish / purple-ish colour cone replacement that looks like the characterizing red cone of Stromberg Carlson.

https://www.ebay.com.hk/itm/18-SPEA...469275?hash=item548179645b:g:CjEAAOSwoQlec86d

Talk to him briefly he seems to be very knowledgeable an able to procure customized cone solution base on the above 18" cone replacement. You may ask him to look at your driver unit and see any chance of restoration.

p.s. Jason has much more feedback on Reverb. He seems to be well received in the pro community.

 

[CopperWizard]

Regarding your woofer rubs, if I am in your position, I would try talking to Jason at Hempo. I hook up with him at eaby seeing a posting of him. It was a reddish / purple-ish colour cone replacement that looks like the characterizing red cone of Stromberg Carlson.

https://www.ebay.com.hk/itm/18-SPEA...469275?hash=item548179645b:g:CjEAAOSwoQlec86d

Talk to him briefly he seems to be very knowledgeable an able to procure customized cone solution base on the above 18" cone replacement. You may ask him to look at your driver unit and see any chance of restoration.

p.s. Jason has much more feedback on Reverb. He seems to be well received in the pro community.

That's awesome! I will certainly do that. Thank you.

 

[zoltm]

Friend shared these notes with me, which may be useful for your restoration too.

According to my friend, who owns 10+ units of this driver, told me that, the capacitor is seldom the faulty point.

The most faulted area is the tweeter.

 

[zoltm]

That's awesome! I will certainly do that. Thank you.

Do report back to this thread about your experience working with Jason @ PMR Hempo. My woofer is currently in ok condition, they are not perfect and have been repaired. As I am prepared to keep the driver long term, hence it would be great to know there is indeed dependable supplier who can look at possibly faithfully repair the driver.

 

[zoltm]

Any kind soul who would know a possible source for a phenolic diaphragm that I could use with the RF-475, please share your precious knowledge.

Many thanks.

 

[RxDx]

There's one at auction. US eb*y item number: 324218453984