Newbie Xmas present problem )o:

Hi Group,
Sorry if my question is a bit "lame" for your group but I'm more
expert with PC related problems.
So what I need enlightened in is that my 15yo son has his existing
Cambridge Audio A1v2 amp and has (in the past ..now blown !!) been working
fine with a pair of standard old 30w rms Pioneer spreakers.
He's now went out after Xmas and spent just over £120 on A pair of Eltax
Symphony 8.3 speakers that have had decent reviews within their
price bracket.
The probem is when he connects the speakers and turns the volume up above
half-way (ok I know it pretty loud.. but he's a teenager (o; ) the speakers
cut out and stutter ... I don't mean distorted and loud but actually
stopping and starting every 1/4 second or so.
I've put the speakers on my kenwwod amp (100rms p/c) and they seem to
perform as you would expect at all volumes.
So we've come to the conclusion that his amp (30w) is not powerful enough
for these new speakers and is in some way malfunctioning.
I'm out of my depth with this one as I've never been aware of this type of
problem before !

ANY advice or confirmation on my conclusion would be greatly appreciated
as my son is now pretty gutted that he may have to wait for
another year to save up for another more powerful amp when up until now he's
been really happy with it.

Cheers

Ian

In article , Ian
wrote:
Hi Group,

He's now went out after Xmas and spent just over £120 on A pair of Eltax
Symphony 8.3 speakers that have had decent reviews within their price
bracket. The probem is when he connects the speakers and turns the
volume up above half-way (ok I know it pretty loud.. but he's a teenager
(o; ) the speakers cut out and stutter ... I don't mean distorted and
loud but actually stopping and starting every 1/4 second or so.

It sounds as if one or the other of two things is happening.

1) The impedance of the speakers is too low or too reactive, and is
triggering a protection circuit in the amp.

2) The impedance of the speakers is inducing instability in the amp, again
triggering a protection circuit.

Afraid I don't know enough about either the amp or the speakers to say
more. If it is (1) then the initial solution is to turn down the power. If
it is (2) it might be possible to modify the connections by adding a small
series inductance.

You could try adding 1 Ohm series resistors to see if this helps. It might
help avoid the problem, but at the expense of a slight reduction in volume,
and a change in the overall tonal balance.

It is possible that the amp is no longer in spec, and may benefit from a
service, but it may just be that the limitation is inherent in the design.

ANY advice or confirmation on my conclusion would be greatly
appreciated as my son is now pretty gutted that he may have to wait for
another year to save up for another more powerful amp when up until now
he's been really happy with it.

Alas, these days, magazines often don't give enough data to allow you to
see the warning signs in advance for things like this. However when looking
for new speakers, watch out for speakers that have an impedance that dips
below about 4 Ohms and avoid them unless you know the amp has a good
current and stability performance.

OTOH not playing the music at mind-squashing levels might help. ;-

You might also like to check the actual power ratings of the Eltec's.
Afraid I don't recall anything about these off-hand. However if he is going
to play loud into them using a low-power amp, then they may eventually be
damaged unless they are generously rated. The standard 'power rating' given
to speakers does not necessarily gurantee you will be 'safe' with a *lower*
power amp if it is clipping or the mean level is consistently very high. It
is not always as simple as "Amp is 30 W, speakers are 50W, so all is safe".

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Ian
wrote:
Hi Group,

He's now went out after Xmas and spent just over £120 on A pair of Eltax
Symphony 8.3 speakers that have had decent reviews within their price
bracket. The probem is when he connects the speakers and turns the
volume up above half-way (ok I know it pretty loud.. but he's a teenager
(o; ) the speakers cut out and stutter ... I don't mean distorted and
loud but actually stopping and starting every 1/4 second or so.

It sounds as if one or the other of two things is happening.

1) The impedance of the speakers is too low or too reactive, and is
triggering a protection circuit in the amp.

2) The impedance of the speakers is inducing instability in the amp, again
triggering a protection circuit.

Afraid I don't know enough about either the amp or the speakers to say
more. If it is (1) then the initial solution is to turn down the power. If
it is (2) it might be possible to modify the connections by adding a small
series inductance.

You could try adding 1 Ohm series resistors to see if this helps. It might
help avoid the problem, but at the expense of a slight reduction in volume,
and a change in the overall tonal balance.

It is possible that the amp is no longer in spec, and may benefit from a
service, but it may just be that the limitation is inherent in the design.

ANY advice or confirmation on my conclusion would be greatly
appreciated as my son is now pretty gutted that he may have to wait for
another year to save up for another more powerful amp when up until now
he's been really happy with it.

Alas, these days, magazines often don't give enough data to allow you to
see the warning signs in advance for things like this. However when looking
for new speakers, watch out for speakers that have an impedance that dips
below about 4 Ohms and avoid them unless you know the amp has a good
current and stability performance.

OTOH not playing the music at mind-squashing levels might help. ;-

You might also like to check the actual power ratings of the Eltec's.
Afraid I don't recall anything about these off-hand. However if he is going
to play loud into them using a low-power amp, then they may eventually be
damaged unless they are generously rated. The standard 'power rating' given
to speakers does not necessarily gurantee you will be 'safe' with a *lower*
power amp if it is clipping or the mean level is consistently very high. It
is not always as simple as "Amp is 30 W, speakers are 50W, so all is safe".

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html