FST tweeter is dead in my new RM 40's

zybar · « **on:** 6 Jan 2004, 07:29 pm »

Well I had Frank (Horsehead) over and he was doing a masterful job of tuning my 40's (looks like I really was doing a ppor job

) when tragedy struck - I started to hear a ringing come from the left speaker. We stopped the music and checked everything and still had the ringing from the left speaker.

The ringing stopped but something didn't sound right. We checked and the FST tweeter on that speaker was not outputing any sound.

I immediately stopped all music and called Brian.

Unfortunately, Brian had just left for CES and wasn't available.

Looks like I will have to wait for him to come back to get a new tweeter.

Has anybody had a tweeter failure? How easy was it to replace in the field?

Thanks again to Frank for his tuning skills and I look forward to having him back up once the speaker is back up and running.

GW

Brian Cheney · « **Reply #1 on:** 6 Jan 2004, 07:51 pm »

Due to the miracle of the laptop I can solve your problem. Sounds like you had an oscillation. Three things to check:

The tweeter itself. Is the diaphragm broken, sagging or shredded? If not take it out by unscrewing the four woodscrews holding it on the baffle (screws are under the foam masks), tilting the speaker forward while holding your hand under the tweeter, and it will fall out. Take a VERY low level music signal and place it across the tweeter input posts (use your speaker wire, just make sure the signal is barely audible) and see if it plays. If it does there are two other possibilities.
#2 is the tweeter level control. If the knob turns freely without detents, it's OK.
#3 is the tweeter cap. TRT caps can be damaged by oscillation. I will send a new one for you to try. You'd have to open the speaker to get to the cap. Not easy but not hard. If you can't solder get a friend who knows how to help.
And have your amp checked.
It's OK to play the speaker with a blown tweeter, so go ahead.

cametz · « **Reply #2 on:** 6 Jan 2004, 07:51 pm »

Been there done it twice. Actually I blew the tweeter and the cap of my RM2. I imagine the tweeters are the same in the RM2 and the RM40 but Brian would be the one to check with.

Replacing the tweeter was done by removing four screws located under the foam covering. A soldering iron or gun will remove the two wires. On the tweeter was a mark for the positive and nevitive terminels. I believe the blue wire was negitive. Resoder the new one on and your set...
that is if it is the tweeter.

Brian instructed me that the only to check was to also take out the tweeter of the working speaker and test it in the non working speaker.
On my second mishap I found the speaker did work and then Brian told me I needed to replace the cap. That's a whole nother story...
Clyde

zybar · « **Reply #3 on:** 6 Jan 2004, 08:10 pm »

Thank you very much Brian for the response.

The membrane is not broken and the pot turns freely.

I will try taking the tweeter out. Silly question, can the tweeter come up out without taking off the foam pads? I don't think so, but don't want to assume wrongly.

GW

Brian Cheney · « **Reply #4 on:** 6 Jan 2004, 08:13 pm »

You may have fried a cap. Give me your shipping address and I'll put one of my spares in the mail to you. Send the old one back please. And check your amp. HF oscillations you can hear are VERY rare.

cametz · « **Reply #5 on:** 6 Jan 2004, 08:14 pm »

If you peal back a little of the foam to find each screw the foam will come out on the tweeter.
Clyde

zybar · « **Reply #6 on:** 6 Jan 2004, 08:29 pm »

B,

I do get sound on the tweeter when I hook up to it directly.

My pair of 40's has the TRT upgrade.

What is an oscillation? Was that the ringing we heard?

GW

warnerwh · « **Reply #7 on:** 6 Jan 2004, 08:49 pm »

If possible it may be a good idea to hook that amp up to some junk speakers and see if you can hear any ringing. If the amp is oscillating it will certainly damage your good speakers again. Also I'd call the amp manufacturer and see what they have to say.

zybar · « **Reply #8 on:** 6 Jan 2004, 09:48 pm »

I am going to bring my amps to Blackie Pagano (best tube repair guy in NYC) tomorrow morning.

Is there anything specific I need to have him look for?

What causes an oscilation?

GW

ekovalsky · « **Reply #9 on:** 7 Jan 2004, 02:16 am »

Sorry about the fried cap. Hopefully it won't be too hard to replace. Sounds like Big B is taking good care of you.

My advice is to sell the Koras and Adcom get a pair of JRDG 201 monoblocks, retail $4700/pr. You may have a little chump change left over. With 500 watts per channel into four ohms, clipping distortion will be a thing of the past. And there will not be any spurious high frequency noise in the output which will fry your precious capacitors or drivers.

If an ICEpower module in a JRDG amp fails, a new unit can be sent to you overnight and easily installed. No soldering, just unscrew a hex nut, pull the connector, remove the bad board, and replace. Beats shipping a huge piece of equipment across the country...

... or to Scandinavia. The Acoustic Reality eAR mkII is probably a near equal of the 201 monos at a lower price. But the service center is in Denmark, just opening the unit will void your warranty, and the connnectors are weird and very cramped. Stay away unless Peter organizes a USA dealer network and service center!

Redbone · « **Reply #10 on:** 7 Jan 2004, 03:42 pm »

zybar, bad news. Well, stuff happens. Hope you can get it fixed easily, sounds like it is the cap. I am wondering what might have caused it, as I am doing a lot of screwy things with mine and would like to avoid blowing a speaker for at least a month or two.

itcperry · « **Reply #11 on:** 8 Jan 2004, 08:43 pm »

Talk to Brian - I have had tweeter cap issues recently and he has done what he can to help me remedy problems. Email sent to you eariler.

Good luck

zybar · « **Reply #12 on:** 8 Jan 2004, 08:54 pm »

Thank you Perry.

I am sure I will talk with Brian as soon as CES is over.

George