Speaker problems

[addzup]

I just bought an ancient Denon AVR-800. Hooked up my Bose 301 speakers and it worked fine for one night. Now only one speaker works. I've switched speakers around and the problem is not the speakers. They both work but only one set of outputs functions on the receiver. The person from whom I bought the receiver said I fried it hooking up the speakers incorrectly. I went on line to find the manual but the receiver is too old. Denon does not even have one in it's archives. I did find a post on line that said you can reset the receiver if the speakers malfunction. My question is, is it fixable? Could it be old speaker wires are faulty? Is there a way to reset it (post said to follow instructions in the manual) Am I wasting my time with this?

 

[TLS Guy]

I just bought an ancient Denon AVR-800. Hooked up my Bose 301 speakers and it worked fine for one night. Now only one speaker works. I've switched speakers around and the problem is not the speakers. They both work but only one set of outputs functions on the receiver. The person from whom I bought the receiver said I fried it hooking up the speakers incorrectly. I went on line to find the manual but the receiver is too old. Denon does not even have one in it's archives. I did find a post on line that said you can reset the receiver if the speakers malfunction. My question is, is it fixable? Could it be old speaker wires are faulty? Is there a way to reset it (post said to follow instructions in the manual) Am I wasting my time with this?

You are wasting your time. That is an old prologic receiver and won't have a reset. It likely did not like the load of your Bose speakers. One amp is now blown.

Take it to the recycling center. Those old prologic receivers are no use now and have minimal value.

 

[jeannot]

Am I wasting my time with this?

I have never seen an amplifier blown because of difficult to drive speakers. If that channel sounded fine before it stopped, then it is likely not a short circuit in the wiring. May be a bad switch, or connection on that channel on the source side (try tuner), or headphones half unplugged, something of the like.

Depends how much you value your time, but beyond that if it was me, that receiver would be on its way to the Environment right now.

 

[TLS Guy]

I have never seen an amplifier blown because of difficult to drive speakers.

I have. All it takes is an wide impedance dip below 400 Hz and highly positive phase angles, and all but the most robust amps will blow if they have no protection. I suspect that old receiver has either no, or rudimentary protection.

 

[addzup]

Thanks. I was afraid of that. The guy hung up on me when I called him back.

 

[highfigh]

Thanks. I was afraid of that. The guy hung up on me when I called him back.

Move all of your controls and switches- if they're dirty, you won't get sound on the channel with the dirty controls or switches.

 

[jeannot]

I have. All it takes is an wide impedance dip below 400 Hz and highly positive phase angles, and all but the most robust amps will blow if they have no protection. I suspect that old receiver has either no, or rudimentary protection.

I take your word that you have seen it, although I can imagine the warranty nightmares it could lead to for manufacturers. Do you think the Bose 301 would display such a harmful impedance?

 

[TLS Guy]

I take your word that you have seen it, although I can imagine the warranty nightmares it could lead to for manufacturers. Do you think the Bose 301 would display such a harmful impedance?

I have no idea, as Bose never publish specs. But in the manual it says the amp has to be four ohm capable. There are two woofers, both different and three tweeters, one different.

So you know the speaker is going to be around four ohms. Since the speaker like all Bose products will be a total mess, Heaven knows what the phase angles are.

A receiver of the vintage the OP has would not like anything less than eight ohms and if the phase angle goes anywhere into positive territory, which is highly likely, then blowing a receiver like that is pretty much a certainty.

Unfortunately few speaker manufacturers are honest about impedance ratings and the phase angles are seldom mentioned. Most speakers are in fact four ohm these days no matter what the manufacturer says. These days you should never select a receiver or amp that is not highly four ohm capable, or it will have a short life with a lot of speakers.

Here is an ATC bookshelf speaker, which is excellent and in my view comes from a series of bookshelf speakers that are right at the front of the pack.

Now if you look at the impedance curves it can honestly be represented as a a 6 to 8 ohm speaker. However look at how far the phase angles go into positive territory. This speaker will seem like almost a dead short at certain frequency. For this series of speakers, robust powerful amplifiers have been found to be mandatory.

Now when you design a speaker you have to take the impedance curve and phase angles you get. Smooth response must trump everything.

Now the late Peter Walker founder of Quad maintained that any self respecting amplifier must be stable into all loads. His were, few others are. That probably goes a long way to explain the extreme longevity of his amplifier designs.

In other words, it is the amplifier designer's responsibility to build amplifiers that will drive any speaker, not the speaker designer's responsibility not to blow amplifiers.

 

[markw]

Unless I missed something here, we're talking about Bose 301's, and they are, or at least were, a two way system with one woofer and one tweeter and, arguably, one of their better values.

 

[Rickster71]

The person from whom I bought the receiver said I fried it hooking up the speakers incorrectly.

Can you elaborate; what would give him that impression?
Did you make your hookups with the power on? Or short the speaker wires?

 

[TLS Guy]

Unless I missed something here, we're talking about Bose 301's, and they are, or at least were, a two way system with one woofer and one tweeter and, arguably, one of their better values.

I failed to notice the manual ran the 201 and 301 together. But the 301 has an 8" woofer and two tweeters. However although it does not give the speaker impedance, it does amps and receiver need to be 4 to 8 ohm load.

This is straight from the 301 user manual.

Driver complement
201®: One 6.5-inch (16.5 cm) woofer. One 2-inch (5 cm) tweeter.
301®: One 8-inch (20 cm) woofer. Two 2-inch (5 cm) high-sensitivity tweeters.
Compatibility/impedance
201: Compatible with amplifiers and receivers rated from 10 to 120 watts per channel.
Rated 4 - 8 ohms
301: Compatible with amplifiers and receivers rated from 10 to 150 watts per channel.
Rated 4 - 8 ohms

And that is as much detail as you can get from their website except for dimensions

 

[addzup]

I hooked up the CD player and speakers before I turned it on. I was careful not to have any stray wire sticking out. The back of the Denon is labeled "Impedance FRONT/6~10 omhs CENTER, REAR/ 8~16 omhs. The Bose speakers are small, bookshelf speakers. I didn't think this receiver would have any trouble handling them and it didn't - for one night.

When I bought the thing the seller told me the center speaker outputs were not working but the front and back were working fine. I find that 99.9% of the people of the world are honest. He told me the reciever was only 10 years old, that it worked and that I could return it if it didn't. I should have done my homework but I believed him. So when I called to tell him it did not work, he said I didn't know what I was doing and I blew it up. Lesson learned.

I am curious, though, if it could be the speakers or speaker wire? I was using a Sony receiver (for years) and it began to sporadically cut off the sound on both speakers. If I turned the receiver off and back on, it would work again for a little while then cut out again. I had the Sony for about 20 years and moved it and hooked it up many times. But maybe it is something that I'm doing? It's hard to believe that receivers can be so sensitive. Or maybe the wires are too old? Can that be true? A friend of mine is willing to lend me her old Pioneer but I'm afraid to try it. And if it is my fault, I'm afraid to buy a new one for the same reason.

 

[jcmccorm]

Have you tried what others have suggested and manipulated the the front panel controls on the receiver? bass/treble/volume. Speaker A/B switch, Loudness switch, whatever. Cycle all of the switches and knobs.

I've got more than one piece of vintage gear and from time to time, one or both speakers will totally drop out and it's always fixed by cycling the switches or knobs.

Cary

 

[markw]

Perhaps, perhaps not.

I failed to notice the manual ran the 201 and 301 together. But the 301 has an 8" woofer and two tweeters. However although it does not give the speaker impedance, it does amps and receiver need to be 4 to 8 ohm load.

This is straight from the 301 user manual.

If you check a little further you'll find that the original 301's were one woofer and one tweeter and satyed that way until the mid eighties. So, depending on what he's packing, either of us could be right, or wrong.

In any case, it does not, and never did have:

There are two woofers, both different and three tweeters, one different.

 

[TLS Guy]

I hooked up the CD player and speakers before I turned it on. I was careful not to have any stray wire sticking out. The back of the Denon is labeled "Impedance FRONT/6~10 omhs CENTER, REAR/ 8~16 omhs. The Bose speakers are small, bookshelf speakers. I didn't think this receiver would have any trouble handling them and it didn't - for one night.

When I bought the thing the seller told me the center speaker outputs were not working but the front and back were working fine. I find that 99.9% of the people of the world are honest. He told me the reciever was only 10 years old, that it worked and that I could return it if it didn't. I should have done my homework but I believed him. So when I called to tell him it did not work, he said I didn't know what I was doing and I blew it up. Lesson learned.

I am curious, though, if it could be the speakers or speaker wire? I was using a Sony receiver (for years) and it began to sporadically cut off the sound on both speakers. If I turned the receiver off and back on, it would work again for a little while then cut out again. I had the Sony for about 20 years and moved it and hooked it up many times. But maybe it is something that I'm doing? It's hard to believe that receivers can be so sensitive. Or maybe the wires are too old? Can that be true? A friend of mine is willing to lend me her old Pioneer but I'm afraid to try it. And if it is my fault, I'm afraid to buy a new one for the same reason.

It appears you need something four ohm capable to drive your speakers. I suspect they are trying to draw too much current from your Sony and your Denon.