Monitor Audio BR5 tweeter blowout !! [Archive] - Audio & Video Forums


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02-25-2009, 08:12 AM
Can anyone help me. For the second time within a month I've blown 2 tweeters. It started after I bought my lovely Marantz CD6002 CD player but this may be a red herring. I'm using the Marantz CD player, an old Pioneer A-400X amp (50W @ 8 ohms, 70W @ 4 ohms). The volume meter never goes past halfway. Bi-wired Monitor Audio cable 5 metre lengths bananna plugged both ends. Thanks folks !

This Guy
02-25-2009, 11:01 AM
The volume meter as in the VU meter (volume unit)? If this is what you mean, everytime it goes pass the halfway point (0) the amp could be clipping, which could fry your tweeters. Maybe get an amp with more headroom (power) so that you don't clip it, or just turn the volume down. As soon as the speakers start to sound not as good as higher volumes, you gotta turn it down.

02-25-2009, 04:41 PM
But please clarify the statement about the volume meter. There are no meters on the Pioneer (or the Marantz). What meter are you talking about?

02-25-2009, 10:26 PM
I don't know why I said meter, I meant volume knob. The strange thing with this problem is the music never starts sounding bad, distorted etc, as the shop suggested. The tweeters just stopped working, I can't determine the point they packed in. I don't think I'm playing the music too loud but maybe for some reason this amp speaker combo doesn't work ? I'm bi-wiring them, maybe this is the problem ? Thanks for your help.

02-26-2009, 06:28 AM
I don't see how bi-wiring could be contributing to this.

It is not reliable to use the knob position to determine how hard you're pushing the amp or speakers.

My guess is that the new CD player is a red herring. I think the new CD player has a hotter output than what you were using before and so the same knob position on the amplifier plays the system at a higher level.

When you say you don't think you're playing the music too loud, what are we to take that to mean? Can you have a normal conversation while the stereo is playing? Do you have any neighbors?

For some reason, very few consumer or even audiophile amplifiers have clipping indicators. That's a shame because without the indicators it is difficult to know when you're putting your tweeters in danger.

02-26-2009, 06:42 AM
how long have you had these speakers? a while i'm guessing? same with the amp?

never had problems before?

audio amateur
02-26-2009, 06:50 AM
At 20$ a pop I'd be blowing 'em too. (as someone once put it)


02-26-2009, 09:34 AM
I've had the speakers about 8 months, the CD player 2 months, the amp 10 years. The previous CD player, Aiwa something or other, no problems and played at the same levels. I've been assured by the shop that it can't be the CD player.

How loud is loud ? I've played too loud years ago with a pair of Celestion Dittons 15XR's and you could hear the clipping when played too loud. I call loud, loud enough so you can talk, have a conversation but rather listen to the music. Hard to compare loudnest over the internet.
The speakers are rated at 6 ohms, do you think as they are easily driven they can't take as much volume ?

02-26-2009, 07:20 PM
If you're convinced you're playing the same loudness as in the past and your amp is not being overdriven (clipping) then another possibility is that someplace along the line ultrasonics have been introduced into your system. This is somewhat rare but does happen. The catch is they are beyond your range of hearing, but can deliver enough power to the tweeters to fry them.

The possible sources are your new CD player, a faulty or inadequately shielded interconnect or your amp has developed a bad part and is oscillating at this high frequency.

Unfortunately there is no good way to check this yourself. Checking the components will require test equipment that few people have at home. You could try a new set of cables but that is just a trial & error approach. You'll just have to see if another tweeter blows and even if it doesn't you still couldn't be sure its been fixed.

Good luck with finding the problem.

02-27-2009, 06:51 AM
Unfortunately there is no good way to check this yourself. Checking the components will require test equipment that few people have at home.Do you have a dog? Dogs can hear ultrasonics. Mice too.

02-27-2009, 08:11 AM
I've got two dogs but unfortunately don't speak dogese. ;-)

02-27-2009, 10:35 AM
Yes I have a white boxer called Charlie and he puts up with Rush for so long before he sulks off out of the room. I've been talking to my Dutch friend and he said when condensers within the amp age they become defective and can cause a peak in the signal which could possible blow the tweeters. I'll look into the ultrasonic idea, thanks for your help.

02-27-2009, 11:06 AM
unless you abused that amp seriously, the capacitors in the amp can't be failing already...
a defective cap usually is drying out, but this happens after 30 years or so. One possebility is that they are leaking, but in both cases, you'd hear a loud pop through the speakers when turning the amp on...

the marantz does have a higher output voltage than your akai, so the speakers will play louder at the same volume knob position...

I can't really find any other reason why they're fried than the amp clipping, but you'd hear it disort before that would happen...

Keep them spinning,

02-27-2009, 11:40 AM
...the capacitors in the amp can't be failing already
You've got to be careful with those "can't be" statements. While one can look at typical MTBF (mean time between failure) numbers for a component, there are certainly parts that fail before their time. No factory puts out a 100% perfect product all the time, including capacitors.

There are also other problems that can induce HF oscillation in an amp, ranging from cold solder joints to dirty or corroded contacts.

There is only one way to find out whether or not any of these are the cause of the original problem. That is to have the components checked with the proper test equipment.