Is my receiver clipping? Shutting down when volume is high.

[Cartrivision1]

Hi, I have a Bang & Olufsen Beocenter 7700 system. It is an "all in
one" center with turntable, FM tuner, and tape deck. It is rated at
40w x 2. It has hookups for 2 sets of speakers.

I bought this thing called a Quatravox Synthesizer, which is some kind
of 70's surround sound/quadraphonic processor. It is supposed to turn
a 2 channel system into a 4 channel. I hooked it up to my system to 2
sets of bookshelf speakers, one set is a Baby Advent II, and the other
set came from a Mitsubishi bookshelf system. The latter set handles 80
watts. When I turn my stereo up past around 36 for a length of time
(it goes to 60 I think) the receiver will power itself down.

I remember hearing about amplifier clipping and I am wondering if this
is what is going on? That the receiver is not putting out enough power
to drive the speakers. The Beocenter does have a set of what looks
like RCA plugs on the back labeled "Preamp Left/Right Out". I am not
sure exactly what these do. Can anybody shed any light on my
situation?


thanks
CTV

[Michael Ware]

"Cartrivision1" > wrote in message
oups.com...
> Hi, I have a Bang & Olufsen Beocenter 7700 system. It is an "all in
> one" center with turntable, FM tuner, and tape deck. It is rated at
> 40w x 2. It has hookups for 2 sets of speakers.
>
> I bought this thing called a Quatravox Synthesizer, which is some kind
> of 70's surround sound/quadraphonic processor. It is supposed to turn
> a 2 channel system into a 4 channel. I hooked it up to my system to 2
> sets of bookshelf speakers, one set is a Baby Advent II, and the other
> set came from a Mitsubishi bookshelf system. The latter set handles 80
> watts. When I turn my stereo up past around 36 for a length of time
> (it goes to 60 I think) the receiver will power itself down.

Have you tried it without the Q box? Just hook up the speakers to the
speaker terminals and see if it behaves the same. My guess is it is just
overheating the amp and shutting itself down.
>
> I remember hearing about amplifier clipping and I am wondering if this
> is what is going on? That the receiver is not putting out enough power
> to drive the speakers. The Beocenter does have a set of what looks
> like RCA plugs on the back labeled "Preamp Left/Right Out". I am not
> sure exactly what these do. Can anybody shed any light on my
> situation?

The preamp out jacks were probably intended to be used with an equalizer or
other signal processor. Are there preamp in jacks as well, connected with a
metal jumper on the back?
>
>
> thanks
> CTV
>

[**THE-RFI-EMI-GUY**]

I may be mistaken, but seem to recall that older B&O stuff used 16 ohm
speakers, you could be overloading the amplifier.

Cartrivision1 wrote:

>Hi, I have a Bang & Olufsen Beocenter 7700 system. It is an "all in
>one" center with turntable, FM tuner, and tape deck. It is rated at
>40w x 2. It has hookups for 2 sets of speakers.
>
>I bought this thing called a Quatravox Synthesizer, which is some kind
>of 70's surround sound/quadraphonic processor. It is supposed to turn
>a 2 channel system into a 4 channel. I hooked it up to my system to 2
>sets of bookshelf speakers, one set is a Baby Advent II, and the other
>set came from a Mitsubishi bookshelf system. The latter set handles 80
>watts. When I turn my stereo up past around 36 for a length of time
>(it goes to 60 I think) the receiver will power itself down.
>
>I remember hearing about amplifier clipping and I am wondering if this
>is what is going on? That the receiver is not putting out enough power
>to drive the speakers. The Beocenter does have a set of what looks
>like RCA plugs on the back labeled "Preamp Left/Right Out". I am not
>sure exactly what these do. Can anybody shed any light on my
>situation?
>
>
>thanks
>CTV
>
>
>

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

[ScottW]

"Cartrivision1" > wrote in message
oups.com...
> Hi, I have a Bang & Olufsen Beocenter 7700 system. It is an "all in
> one" center with turntable, FM tuner, and tape deck. It is rated at
> 40w x 2. It has hookups for 2 sets of speakers.
>
> I bought this thing called a Quatravox Synthesizer, which is some kind
> of 70's surround sound/quadraphonic processor. It is supposed to turn
> a 2 channel system into a 4 channel. I hooked it up to my system to 2
> sets of bookshelf speakers, one set is a Baby Advent II, and the other
> set came from a Mitsubishi bookshelf system. The latter set handles 80
> watts. When I turn my stereo up past around 36 for a length of time
> (it goes to 60 I think) the receiver will power itself down.
>
> I remember hearing about amplifier clipping and I am wondering if this
> is what is going on? That the receiver is not putting out enough power
> to drive the speakers. The Beocenter does have a set of what looks
> like RCA plugs on the back labeled "Preamp Left/Right Out".

Preamp outputs are just what it says... preamp outputs...
the signal before it goes through the power amp.

> I am not
> sure exactly what these do. Can anybody shed any light on my
> situation?

I have no idea what Quatravox does... but I'm quessing the
Beocenter is shutting down for its own protection.
Are both sets of speakers at least nominally 8 ohms?
You might be presenting to low an impedance to the amp.
Try hooking one set of speakers straight to the B&O
and see if it still shuts down. Then the other.
Then both. If it only shuts down with both...its most likely
because one pair or the other or both are less than 8 ohms.
I'd yank the Quatra thing anyway and see how stereo
sounds.

ScottW

[Cartrivision1]

I checked and it seems that my particular Bang & Olufsen stereo uses 4
ohm speakers:

Power output RMS DIN: 2 x 40 W / 4 ohms
Harmonic distortion: <0,1%
Intermodulation: <0,3%
Frequency range + / - 1,5 Db: 20 - 30000 Hz

Could this be the root of my problem?



thanks,
CTV

[ScottW]

"Cartrivision1" > wrote in message
oups.com...
>I have been running the Advents with the Beocenter for a a couple years
> now with no problems. And the other set of speakers are definetly 8
> ohms, I just checked. I wanted the Quatravox processor because it is
> supposed to do a good job of decoding both surround and Quad sources.
> And it also gives me an excuse to hook up 2 sets of speakers in my
> living room! I could just hook up the other set straight to the
> Beocenter as it has 2 sets of speaker connections, but it uses special
> speaker cables which I don't have right now.

I think that is what you need to try to see which piece is at fault.
Try just one set of speakers. Does it still fault..then it is has to
be the B&O or the speakers... most likely the B&O.
If that works add the second pair of speakers.
If that works its obviously the Quadrovox.

Good luck.

ScottW

[ScottW]

"Cartrivision1" > wrote in message
ups.com...
>I checked and it seems that my particular Bang & Olufsen stereo uses 4
> ohm speakers:
>
> Power output RMS DIN: 2 x 40 W / 4 ohms
> Harmonic distortion: <0,1%
> Intermodulation: <0,3%
> Frequency range + / - 1,5 Db: 20 - 30000 Hz
>
> Could this be the root of my problem?

No... it you hook up both sets of 8 ohms speakers
to the B&O you have 2 speakers in parallel on each channel
which should be ~4 ohms. It could be one of your
speakers isn't really 8 ohms or that Quad box
presents a less than 4 ohm load and the B&O
is just protecting itself.

If you have 8 ohm speakers, hooking up both pairs
to the B&O should not be a problem.

ScottW

[**THE-RFI-EMI-GUY**]

Nope should be OK. Another problem could be if the B&O requires the
speakers to be floating without reference to ground. Your quad convertor
or external speakers may be shorting the output to ground.

Cartrivision1 wrote:

>I checked and it seems that my particular Bang & Olufsen stereo uses 4
>ohm speakers:
>
>Power output RMS DIN: 2 x 40 W / 4 ohms
>Harmonic distortion: <0,1%
>Intermodulation: <0,3%
>Frequency range + / - 1,5 Db: 20 - 30000 Hz
>
>Could this be the root of my problem?
>
>
>
>thanks,
>CTV
>
>
>

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P