did i ruin this receiver i just bought?

[_shadowFIX]

hi all, relative newbie, so go easy on me haha.

i just bought a Kenwood vr-407 (100 watts/channel, 8-16ohm variable) and unwittingly connected my old c. 1975 Tandberg speakers to it (4 ohm, 40w). the receiver started distorting pretty bad after a couple short minutes. it is now distorting even through properly impedance matched speakers. did i ruin it in just a few short minutes of overworking the amplifier with the low impedance?

for context, i drove these speakers for over 2 decades with a Denon AVR 1403, which upon investigation has a minimum impedance of 6 ohms. it started distorting after over 20 years of faithful service, which in hindsight may be the result of an impedance mismatch that finally caved in.

thanks for the assistance, happy to provide any additional information as needed.

 

[TLS Guy]

hi all, relative newbie, so go easy on me haha.

i just bought a Kenwood vr-407 (100 watts/channel, 8-16ohm variable) and unwittingly connected my old c. 1975 Tandberg speakers to it (4 ohm, 40w). the receiver started distorting pretty bad after a couple short minutes. it is now distorting even through properly impedance matched speakers. did i ruin it in just a few short minutes of overworking the amplifier with the low impedance?

for context, i drove these speakers for over 2 decades with a Denon AVR 1403, which upon investigation has a minimum impedance of 6 ohms. it started distorting after over 20 years of faithful service, which in hindsight may be the result of an impedance mismatch that finally caved in.

thanks for the assistance, happy to provide any additional information as needed.

I think the more likely scenario is that your speakers are blown. I suspect the speakers have been overdriven and now have damaged voice coils likely to lower the impedance and blow receivers and amps.

The first thing you need to do is to check the DC resistance of both your speakers with a multimeter. The DC resistance of each speaker should be at least 3.2 to 3.5 ohms and probably should be around 3.5 ohms. The DC resistance will always be a little less that the impedance rating.

My strong hunch is that those Tandberg speakers are now lethal to amplifiers.

 

[jinjuku]

I find it hard to believe that you fried your AVR unless there is something wrong with the load (your Tandbergs) you gave it.

Do the other channels still work or are they distorted also?

 

[_shadowFIX]

I think the more likely scenario is that your speakers are blown. I suspect the speakers have been overdriven and now have damaged voice coils likely to lower the impedance and blow receivers and amps.

The first thing you need to do is to check the DC resistance of both your speakers with a multimeter. The DC resistance of each speaker should be at least 3.2 to 3.5 ohms and probably should be around 3.5 ohms. The DC resistance will always be a little less that the impedance rating.

My strong hunch is that those Tandberg speakers are now lethal to amplifiers.

oof, man it makes sense, but i hadn't even considered that as a possibility. i don't have a multimeter, but it looks like i can pick one up at like Walmart for pretty cheap. so essentially, something could be faulty in the Tandbergs, possibly changing the impedance even lower than what they're rated for, causing them to kill basically any amp i plug them into?

I find it hard to believe that you fried your AVR unless there is something wrong with the load (your Tandbergs) you gave it.

Do the other channels still work or are they distorted also?

just tried a properly matched speaker on one of the surround channels, also distorted. at least this was a (relatively) cheap accident if in fact i killed it. picked up the AVR cheap on Craigslist, so i won't be broke and destitute over this haha.

 

[lovinthehd]

What kind of levels are you driving these speakers to?

 

[_shadowFIX]

What kind of levels are you driving these speakers to?

i only did easy listening/testing levels, definitely wasn't trying to bring the roof down.

 

[lovinthehd]

i only did easy listening/testing levels, definitely wasn't trying to bring the roof down.

Then I'd tend to think of a speaker problem as well (rather than user). How does the distortion manifest itself particularly?

 

[_shadowFIX]

Then I'd tend to think of a speaker problem as well (rather than user). How does the distortion manifest itself particularly?

i think i know what you mean by "how does it manifest" - for what it's worth, it definitely isn't physical like a damaged cone or surround would sound like. it was faint at first, almost like the speakers just weren't happy being driven a little hard, but then it became obvious that it was originating from the amplifier when it happened even at the softest volumes and on other speakers as well.

i've got a friend stopping by with a multimeter later this afternoon, i'll report back what we find!

 

[_shadowFIX]

ok gang the answer is decidedly user error! i had my source (a Tascam audio interface for my computer) volume up high enough that it was clipping. a better balance of source and receiver volume control resulted in a lovely sound from the Tandbergs!

so, for my final question: i understand that running 4ohm speakers on a receiver with a minimum rating of 8ohms is "fine, but." the but being, just keep volume in check and it should be fine...right?

 

[lovinthehd]

ok gang the answer is decidedly user error! i had my source (a Tascam audio interface for my computer) volume up high enough that it was clipping. a better balance of source and receiver volume control resulted in a lovely sound from the Tandbergs!

so, for my final question: i understand that running 4ohm speakers on a receiver with a minimum rating of 8ohms is "fine, but." the but being, just keep volume in check and it should be fine...right?

Nice, perhaps an example of providing details of the whole system, too. Yes, generally keeping volume in check will work just fine.

 

[diwit]

hi all, relative newbie, so go easy on me haha.

i just bought a Kenwood vr-407 (100 watts/channel, 8-16ohm variable) and unwittingly connected my old c. 1975 Tandberg speakers to it (4 ohm, 40w). the receiver started distorting pretty bad after a couple short minutes. it is now distorting even through properly impedance matched speakers. did i ruin it in just a few short minutes of overworking the amplifier with the low impedance?

for context, i drove these speakers for over 2 decades with a Denon AVR 1403, which upon investigation has a minimum impedance of 6 ohms. it started distorting after over 20 years of faithful service, which in hindsight may be the result of an impedance mismatch that finally caved in.

thanks for the assistance here skateboards guides, happy to provide any additional information as needed.

It is possible that connecting the 4-ohm Tandberg speakers to the Kenwood VR-407 receiver caused it to distort and potentially caused damage to the amplifier. The lower impedance of the speakers compared to the receiver's specified range could overload the amplifier and cause it to work harder than it is designed for.
Distortion is often an indication of strain on the amplifier, and prolonged operation under such conditions can lead to overheating and damage. It's important to match the impedance ratings of the speakers and the amplifier to avoid these issues.
To assess the extent of the damage and determine if the amplifier can be repaired, it would be best to consult with a professional audio technician or contact Kenwood's customer support. They will have the expertise to diagnose the issue and provide guidance on potential repairs or replacements.

 

[Teetertotter?]

This thread is a month old and wonder if there was a solution or not. A response would be nice to possibly help others.