On Sun, 15 Feb 2004 09:37:28 GMT, Bob Latham
wrote:

I've been trying for some time to get to the bottom of a problem I've been
having with an AV8. I have come close to buying one because in general it
is an excellent piece of kit and sounds very, very good indeed.

My problem is to do with centre speakers. My front left and right are of
late 1970s design and I'm not going to change them (still think they're
great) but matching a centre speaker would be all but impossible and in
all probability very expensive. I also don't care much for centre jobbies
as they are difficult to place and most sound quite boxy to me.

So you guessed it, for some years now I've used my Yamaha surround decoder
in phantom mode which has been fine. If I try this with the AV8 then
everything is not fine, there is just far too much centre channel in the
mix. Vocalists are in your face whilst the band is in the garden and film
dialogue is loud with sound effects diminished substantially.

I contacted Arcam and asked them if either in software or hardware a
change to this balance could be made in the factory prior to despatch.
Their reply whilst polite, was unhelpful and was just short of telling me
I was barking mad. They insisted that no change of this nature was
possible and that no one else had complained about phantom mode.

I think the truth is that ARCAM have not spent any real time trying the
AV8 in phantom mode because I suspect they falsely believed that anyone
spending that much money on an AV processor would not be trying to do
without a centre speaker.

Has anyone else tried phantom mode on a decoder and found problems and/or
solutions?

So I'm left wondering....

1) Why does the balance seem so wrong to me in the first place?

Is it just possible that your speakers are to blame?
Try another pair to see if they exhibit the same problem.
I'm thinking that maybe due to the high quality of the AV8 it is
giving a really good center image, which your speakers due to design,
materials etc.. are just doing a really good job of producing.

2) Why is it so difficult to change the mix?
Because you are not doing anything special in the decoding process.
The center channel is being decoded as required by the DD or DTS
formats. It is then simply split and given in equal quantities to the
front pair. The AV8 shouldn't be doing anything to the center level at
all.


3) Why have they disabled the centre volume control when in phantom mode?
Because all that does is change the level of amplification to the
center speaker terminals, if they are not being used then you arn't
going to hear a difference. No sound level calibration is done during
the decoding process (other than that stipulated by DD or DTS formats)
therefore all AV AMP's can do is adjust the amplification levels.

4) Have ARCAM tried the AV8 in phantom for any length of time?
Probably not, but I'm betting they are not doing anything different to
the other manufactorers.

Have you tried setting up the system in full 5.1, adjusting the center
level right down and then switching back to phantom mode?

I have owned 3 AV AMPS (Kenwood, Yammy and Denon) and none have ever
been able to adjust the center level in phantom mode.

Regards.

Ray.

I've been trying for some time to get to the bottom of a problem I've been
having with an AV8. I have come close to buying one because in general it
is an excellent piece of kit and sounds very, very good indeed.

My problem is to do with centre speakers. My front left and right are of
late 1970s design and I'm not going to change them (still think they're
great) but matching a centre speaker would be all but impossible and in
all probability very expensive. I also don't care much for centre jobbies
as they are difficult to place and most sound quite boxy to me.

I couldn't agree more. I've got a pair of Monitor Audio MA202
floorstanders (8-9 years old now). They are hooked up to an Arcam
Alpha 9, which is connected to the line-outs on a Yamaha DSP-A595. On
several occasions I have tried using various centre speakers, and
every time I go back to using the mains with a phantom centre. It
seems to be pretty much impossible to get a good tonal match between a
centre and main speakers unless the manufacturer is deliberately
selling the same drivers in the same cabinets for both roles.

I have owned 3 AV AMPS (Kenwood, Yammy and Denon) and none have ever
been able to adjust the center level in phantom mode.

A bit puzzled here - I'm pretty sure I can adjust the centre level on
my Yamaha DSP-A595a in phantom mode. I haven't actually needed to, as
in theory it shouldn't be necessary with a phantom centre, but I seem
to recall the adjustment being there if I want it.

Simon