Bad crossovers?

bhood

I just purchased a pair of Monitor 70's and hooked them up to a Denon AVR2808. I played around a little last night and everything worked great. Today, I ran the EQ setup using the microphone attached to the receiver. I am now getting no high frequencies.

I have since removed the jumpers from between the binding posts and have hooked the cables up to each pair to test. I am getting the mid/bass from the bottom pair of posts, but nothing from the top pair. Not even a scratchy signal from the tweeters.

This is the same situation on both speakers.

Any advice?

Thanks.

bhood

I am running a single pair of wires to each speaker, so I am using the same pair to test both sets of binding posts with the bridge removed.

What has me puzzled is that they sounded fine before I ran the mic test from the receiver. I have reconnected the Klipsch that I replaced and have the full sonic spectrum.

Thanks.

apphd

bhood, welcome to CP. It does sound like maybe the tweeters are blown, just strange the way it happened. When you brought the Klipsch back into the picture did you rerun the EQ setup? You could try running it again with the Polks, maybe look in the manual to see if there is a reset procedure to get the Denon back to original settings first, then run Audyssey. Maybe it picked up something strange that caused this, I find it hard to believe it would EQ out the whole upper end, but it's worth a try.

bhood

apphd, I did not rerun the EQ setup after re-hooking the K's. I'll give it a try, but if I am getting no high end sound from the upper posts, it sounds like an electrical failure in the Polks.

Do you know if it would void the warranty if I were to remove the tweeters and test at Very low volume?

Thanks.

F1nut

How far did you turn up the volume?

bhood

Ok. I've pulled a tweeter from the Polks and hooked one of the horns from the Klipsch and am getting audio. I don't know what could have blown the tweeters. They were fine before trying to set the EQ. I did not have the volume higher than -15.00 +/-.

Can Polk C/S help me to get replacement tweeters?

F1nut

I did not have the volume higher than -15.00 +/-.

Ah, one of those types....ugh. Anyway, I'm willing to bet that is simply too much volume, which resulted in your AVR clipping, which in turn cooked the tweeters.

ben62670

I hope you weren't boosting the treble, or running any sort of sine wave at that volume. Do you know how to use/have an ohm meter?

royalty

Is that bad of clipping (bad enough to blow the tweets) normal for that level of volume? Just seems kind of low....

F1nut

There is no such thing as good clipping. It takes is less than a second to cook a tweeter...well, two in this case.

nms

royalty wrote: »

Is that bad of clipping (bad enough to blow the tweets) normal for that level of volume? Just seems kind of low....

Depends on how hard your amp was working to produce that "arbitrary" level. The indicated "-15 dB" really doesn't mean anything.

For instance, with certain low-impedance speakers, my amp clips out about 3/4 of the way to max volume. Fortunately, it has overload protection so it won't send a clipped signal to the speakers and break something.

At high volume levels the tweeters do a LOT of work and are really small for the amount of power they absorb. Their watts/area is much higher than midrange or bass drivers.

bluzrip

My older Monitor 10 Polks have fuses on the tweeters. Same with my Monitor 5's. I am uncertain if your model has any such tweeter protection.

BTW, a tweeter can be safely tested to see if it is 'dead or alive' by using a C or D flashlight battery to MOMENTARILY complete a circuit that includes the battery and the tweeter's + and - terminals. Some scratchy sounds should present themselves.

Good luck.