Chorus tweeters not working

[CECAA850]

12 hours ago, Alexander said:

Not to claim to be an expert by any means but usually only the tweeter gets hurt unless something in the crossover goes and then could take something else out with it. Maybe we can get some of the big boys in here and help out.

I could see a crossover being an issue but not both crossovers.

[CECAA850]

http://sound.whsites.net/tweeters.htm

[KA1J]

Possibly the answer. I don't recall if one was added with the recap kit I received from Bob Crites. We're fortunate to have his updates as a resource.

 

Here's a pic of one of the burnt coils.

 

 

[CECAA850]

Too much current.

[KA1J]

19 minutes ago, CECAA850 said:

Too much current.

 

Thanks for that, what would cause too much current?

[CECAA850]

13 minutes ago, KA1J said:

 

Thanks for that, what would cause too much current?

Did you read the link I supplied?

[Alexander]

1 hour ago, CECAA850 said:

I could see a crossover being an issue but not both crossovers.

The point I was making was his concern about hurting the other drivers in the process and that it might take a failure in the crossover to do that all at the same time. And of course that is not the only way the mid or woofer could fail.

[CECAA850]

4 minutes ago, Alexander said:

The point I was making was his concern about hurting the other drivers in the process and that it might take a failure in the crossover to do that all at the same time. And of course that is not the only way the mid or woofer could fail.

Gotcha.

 

I'm thinking that the only thing those two tweeters have in common is the amp and there's no protection on them from what was written on the first page.

[pzannucci]

3 hours ago, CECAA850 said:

Gotcha.

 

I'm thinking that the only thing those two tweeters have in common is the amp and there's no protection on them from what was written on the first page.

Overdrive and do tube amps like to DC?  Maybe that would have affected the other drivers too but obviously those voice coils overheated and fried.  DC or overdriven or both.

[Deang]

Most tube amps have coupling capacitors, and capacitors won’t pass DC. However, a shorted cap will pass all DC - and if that happens, you’ll have more than toasted tweeters. It happened to me once, and both loudspeakers caught on fire in my living room. 

 

Did you inspect the crossovers? 

 

It’s more than possible that you pushed your amp into clipping - and that will take out a tweeter (or two) in short order - about the time it takes to get through Lucky Man. :-)

[KA1J]

7 hours ago, CECAA850 said:

Did you read the link I supplied?

Hi,

 

Yes I did and thanks for the link, it was interesting. The things I have to wonder is about the power levels involved. From what I've read the tweeter is rated at 100W continuous and I've run the amp rarely above 60% and there's no music I have or listen to that would be compressed as the article described. Aside from some 60-70's rock & some country most of the music I have is acoustic, recorded with microphones. I have recently listened to some movies but rarely that loud. That said I did listen to Attack of the Clones loudly but that was to enjoy the pair of SVS PC-4000 subwoofers during the ship exploding and I turned it down after the explosion. BTW, with those subwoofers the house shook like an earthquake. As to music; most everything I have is stereo & wonder what issue issue in both amplifiers would distort cause this bilateral failure. 

 

The article might have hit the nail on the head, I don't know. That said... I've discovered the mids are sounding a tad distorted when the volume is turned up, not terrible but obviously not right. I disconnected the mid and played with just the new tweeter and the woofer alone and zero distortion at 60%, the power that caused the artifacts in the mids.

 

The Forte II pair are just fine at any volume and with that I have to wonder if it is the crossovers in the Chorus that might be the problem & with that, I just ordered a pair of Bob Crite's crossovers & will install them next week. I'm at a point where I have to fix the cause of the problem or it will happen again with the new drivers. 

 

The mids spec out properly resistance-wise 11.5 & 12.1 ohms and may be good so I'll wait till the crossovers are installed & see how the mids sound & if they're all good, that's that. If not, I'll have to find new phenolic mids for them and should be good to go.

 

I will report back with whatever I find.

 

Thanks again for all the thoughts.

[CECAA850]

Take a look at the mid diaphragms while you have everything apart.

[John Chi-town]

INMHO, you are expecting more than the MAC, 2 channel amp can support with swings well blow 4 OHM.  My guess is that you may encounter the same problem again.

 

Best regards,

John

[Alexander]

4 hours ago, John Chi-town said:

INMHO, you are expecting more than the MAC, 2 channel amp can support with swings well blow 4 OHM.  My guess is that you may encounter the same problem again.

 

Best regards,

John

In MHO too.

I could be wrong of course but to continue to wire your speakers in parallel you will most likely see this problem again.

In a SS amp it would hurt the amp doing this, how about tube amps?

 

[pzannucci]

8 hours ago, KA1J said:

Hi,

 

Yes I did and thanks for the link, it was interesting. The things I have to wonder is about the power levels involved. From what I've read the tweeter is rated at 100W continuous and I've run the amp rarely above 60% and there's no music I have or listen to that would be compressed as the article described. Aside from some 60-70's rock & some country most of the music I have is acoustic, recorded with microphones. I have recently listened to some movies but rarely that loud. That said I did listen to Attack of the Clones loudly but that was to enjoy the pair of SVS PC-4000 subwoofers during the ship exploding and I turned it down after the explosion. BTW, with those subwoofers the house shook like an earthquake. As to music; most everything I have is stereo & wonder what issue issue in both amplifiers would distort cause this bilateral failure. 

 

The article might have hit the nail on the head, I don't know. That said... I've discovered the mids are sounding a tad distorted when the volume is turned up, not terrible but obviously not right. I disconnected the mid and played with just the new tweeter and the woofer alone and zero distortion at 60%, the power that caused the artifacts in the mids.

 

The Forte II pair are just fine at any volume and with that I have to wonder if it is the crossovers in the Chorus that might be the problem & with that, I just ordered a pair of Bob Crite's crossovers & will install them next week. I'm at a point where I have to fix the cause of the problem or it will happen again with the new drivers. 

 

The mids spec out properly resistance-wise 11.5 & 12.1 ohms and may be good so I'll wait till the crossovers are installed & see how the mids sound & if they're all good, that's that. If not, I'll have to find new phenolic mids for them and should be good to go.

 

I will report back with whatever I find.

 

Thanks again for all the thoughts.

If you are looking for a fix, I would not be running both those speakers in parallel on that amp.  You are pushing extremely low loads which is likely causing the amp some "anxiety" (technical term ).  If the caps and crossover were at fault, I don't think your voice coil would have been toasted like that without some very high powers going into it.... IMHO.

[KA1J]

On 2/23/2018 at 7:41 AM, pzannucci said:

If you are looking for a fix, I would not be running both those speakers in parallel on that amp.  You are pushing extremely low loads which is likely causing the amp some "anxiety" (technical term ).  If the caps and crossover were at fault, I don't think your voice coil would have been toasted like that without some very high powers going into it.... IMHO.

 

I can appreciate that.

 

The MC275 has 4, 8 & 16 ohm output options, I'd think that the amp would be designed to deal with any of the combinations it was connected to. I think... even if the amp were connected at its 8 ohm terminals & the speakers were at 4 ohms, it would be even easier on the amp. Just conjecture, I don't know. It seems though if there are connections on the amp for 4 ohms, it would be designed to handle whatever swings come its way from the speakers. I remember how much fuller the sound when I had Advents hooked up in parallel, I liked the way the Chorus and Forte sounded together for the same reason.

 

That said, I suppose I could use one of the pairs elsewhere in the house, I have a NAD SS amp that hasn't been used since I picked it up, can't recall the model, weighs maybe 70 pounds with its huge toroidal transformer, can't think where it'd fit in. That, or I'd have to Craigslist one of the pairs, all four on the floor take up a lot of space.

 

So much I don't know the answers to.

[pzannucci]

3 hours ago, KA1J said:

 

I can appreciate that.

 

The MC275 has 4, 8 & 16 ohm output options, I'd think that the amp would be designed to deal with any of the combinations it was connected to. I think... even if the amp were connected at its 8 ohm terminals & the speakers were at 4 ohms, it would be even easier on the amp. Just conjecture, I don't know. It seems though if there are connections on the amp for 4 ohms, it would be designed to handle whatever swings come its way from the speakers. I remember how much fuller the sound when I had Advents hooked up in parallel, I liked the way the Chorus and Forte sounded together for the same reason.

 

That said, I suppose I could use one of the pairs elsewhere in the house, I have a NAD SS amp that hasn't been used since I picked it up, can't recall the model, weighs maybe 70 pounds with its huge toroidal transformer, can't think where it'd fit in. That, or I'd have to Craigslist one of the pairs, all four on the floor take up a lot of space.

 

So much I don't know the answers to.

You do know that is nominal impedance.  Likely going down into the 2's with both speakers.  You fried the tweeters, not bottomed them out, cooked.  A lot of stray power must have been at hand unless you have problems with the crossovers.  Doubtful because the don't look like they bottomed out.  Just a word of caution.  Also aren't the woofers 4 ohm on at least the forte's?

[Deang]

Both the Forte and Chorus drop to 4 ohms at around 140Hz - so 2 ohms or lower when run in parallel.

 

Next to go up in flames is the amplifier. 

[KA1J]

The Chorus is here  http://assets.klipsch.com/product-specsheets/Chorus-brochure.pdf

The Forte II is here http://assets.klipsch.com/product-specsheets/forte-II-brochure.pdf

 

They didn't list the individual speakers but a google said the Forte's K-25-K is 4 ohm by itself. I'm surprised the Chorus suffered as it did and all I can do is repair it, I have the two Crites Crossovers on the way and I know they'll be good. I'll have to listen to each speaker pair & decide which one to keep. I can as mentioned, use the NAD with them elsewhere in the house but it has far more output than the MC275 and I don't care to boatanchor the Chorus again.

https://www.stereophile.com/content/nad-218-thx-power-amplifier-specifications

 

To that end, maybe I should experiment with Ti mids on the Chorus and add on whatever circuitry needs to be to the new crossovers to work best with them. Sure would be nice to be able to A > B phenolic vs Ti with the Crites crossovers.

 

Perhaps my better bet would be to look into modern 3-way speakers with the MC ( I do have a pair of SVS PB16-Ultra Subwoofers to handle the lows) and use the smaller Forte as rear speakers with the NAD driving them for surround for theater & sell the Chorus on Craigslist this summer.

 

Lotsa decisions... The input has been very helpful.