What was going on?

[GranteedEV]

I had some EMP E5Bis lying around. something like 85db, 8 ohm nominal speakers, though I can't say for sure. They're there for when I eventually add some rear surround mounts and wiring for 7.1

I figured I'd set em up in my bedroom for fun. What I've lacked is something to drive them with.

And then I came across some sony boombox thing my sister had gotten a long time ago, in a galaxy far far away.

Now the speakers it came with were interesting in their own right. I don't think I've ever bothered to give them a listen at all... some 3-way bookshelves with a little 6" or so MCM or visaton type woofer and a tiny midrange, tinier tweeter. On the back of them they say they've got a rated impedance of 6 ohms.

Now you know that I know that rated impedance never means much.

But I figured an amp that says "recommended load 6-16 ohm" on the back would drive some 8 ohm bookshelves... it's not like I was looking to blast them. It was (is) like midnight with everyone else asleep. I was just curious to see if I got sound out of them.

So I turn the little integrated amp/cdplayer thing on, hook it up, and turn it on. No sound. So one-by-one, i start to raise the volume. By the digital volume indicator, it went something like Min..1...2..3..4..5..no sound...6...no sound...and then it was very loud, probably like 75db. Now it wasn't consistently loud. It was shifting from nothing to sound back to nothing. Confusing to say the least.

Nothing i particularily care about, as it's just a junk plastic boombox receiver, but i did get curious. It's easy to mess around with perfectly fine electronics... it's the poor ones that are intruiging.

My two theories are

1) Crossover distortion?
2) Ridiculously low RMS power (Possibly not even a few mW?) with decent dynamic power (probably closer to a watt?) couped to some sort of electronic limiter?

but i'm curious. maybe when i get time and no one is asleep i'll try it again at a higher volume to see if i still get this effect.

 

[jcmccorm]

Dirty contact on the volume control?

Cary

 

[KEW]

Ideally, if you have a source to provide a steady sound (so it is not subject to the pulses of music), you can turn it up until the sound comes on, then turn it back down. Most likely, once the connection has been made, it will continue to play a lower levels.
I had a unit that behaved similarly-but mainly on one channel. It turned out that the muting toggle switch spring had broken. The switch would still go to either of the two positions, but did not have enough force behind it to fully make the contacts in the mute off position.

 

[highfigh]

I had some EMP E5Bis lying around. something like 85db, 8 ohm nominal speakers, though I can't say for sure. They're there for when I eventually add some rear surround mounts and wiring for 7.1

I figured I'd set em up in my bedroom for fun. What I've lacked is something to drive them with.

And then I came across some sony boombox thing my sister had gotten a long time ago, in a galaxy far far away.

Now the speakers it came with were interesting in their own right. I don't think I've ever bothered to give them a listen at all... some 3-way bookshelves with a little 6" or so MCM or visaton type woofer and a tiny midrange, tinier tweeter. On the back of them they say they've got a rated impedance of 6 ohms.

Now you know that I know that rated impedance never means much.

But I figured an amp that says "recommended load 6-16 ohm" on the back would drive some 8 ohm bookshelves... it's not like I was looking to blast them. It was (is) like midnight with everyone else asleep. I was just curious to see if I got sound out of them.

So I turn the little integrated amp/cdplayer thing on, hook it up, and turn it on. No sound. So one-by-one, i start to raise the volume. By the digital volume indicator, it went something like Min..1...2..3..4..5..no sound...6...no sound...and then it was very loud, probably like 75db. Now it wasn't consistently loud. It was shifting from nothing to sound back to nothing. Confusing to say the least.

Nothing i particularily care about, as it's just a junk plastic boombox receiver, but i did get curious. It's easy to mess around with perfectly fine electronics... it's the poor ones that are intruiging.

My two theories are

1) Crossover distortion?
2) Ridiculously low RMS power (Possibly not even a few mW?) with decent dynamic power (probably closer to a watt?) couped to some sort of electronic limiter?

but i'm curious. maybe when i get time and no one is asleep i'll try it again at a higher volume to see if i still get this effect.

Crossover distortion? That's way beyond where I would be looking. If it has been sitting idle, the controls and switches are dirty.

 

[3db]

+1 on what jcmccorm and highfigh have said. Thereis definately a dirty and or oxidized volume control. Don't over think this.