Un-matched amps in an active system?

Posted by: London Lad on 29 December 2003

I seem to remember reading somewhere here a thread about running un-matched amps in an active system but I can’t find it now.

Could you for instance run a 150 for the HF and a 250 for the LF via a late SNAXO ?

I seem to remember the thread said something about all Naim amps having the same gain but this doesn’t seem right to me ?

Surely 50% on the volume control would give more output on a 250 than a 150 ?

Has anyone tried it ?

Graham.

Not a lad any longer and not from London!
Posted on: 29 December 2003 by Rockingdoc
The ability of the SNAXO to alter the input to each amp channel for both HF and LF means you could probably get a decent result. As supplied the SNAXO is wired for one stereo amp supplying each speaker. It has to be modded to allow one stereo amp for HF and another for LF.

BTW playing with the HF/LF levels in the SNAXO can be addictive. I now have to leave mine uncased as I find different recordings benefit hugely from little tweaks of the crossover. I'm using it as a tone control, I admit it.
Posted on: 29 December 2003 by London Lad
Rockingdoc

My snaxo (new last week) came wired and labled as 1 amp for LF and one amp for HF.

I was more concerned about the gain of each amp.

Graham.

Not a lad any longer and not from London!
Posted on: 29 December 2003 by Rich Jerskey
The NEW SNAXO 242 is set up differently from the older version. With this new SNAXO you are using one amp to power Hi-frq and one to power Lo-frq. You can adjust the relative levels inside by playing with the pots. Naim has marked the default positions in case you want to go back. I had them adjust mine for SBL's. I'm using an old chrome 250 for lo and a newer olive 250 for hi but I've tried each both ways and not much difference favoring one amp over the other (as long as amps are in excellent repair). This is a more robust way of going active I believe when you think about it. The whole point is to drive the different boxes separately and this is a more direct way of accomplishing that. In your case, try the better amp on hi freq and vice versa to see if you detect any mismatch. It's good to have both amps fairly close power-wise. This is all assuming you're using a new SNAXO. With an old SNAXO the amps should be virtually identical.
Hope this helps.

Regards,

Rich
Posted on: 29 December 2003 by Frank Abela
London Lad,

The gain on Naim power amps is the same across the board, so you can mix 'n' match without worry. It's another nicety of the Naim upgrade path.

Use the more powerful amplifier on the high frequency unit for the better result. I'm fairly sure Naim put this in their manuals.

Regards,
Frank.
All opinions are my own and do not reflect the opinion of any organisations I work for, except where this is stated explicitly.
Posted on: 29 December 2003 by London Lad
Frank,

I'm sure I'm just being thick but a 250 is louder at a given volume control setting than a 150 so how is the gain the same ?

Graham.

Not a lad any longer and not from London!
Posted on: 29 December 2003 by Frank Abela
No, not thick, just deaf. Smile

For a given volume setting the 250 should be the same loudness as the 150. It just seems louder courtesy of the extra grip, resolution blah blah, but the gain is the same.

Regards,
Frank.
All opinions are my own and do not reflect the opinion of any organisations I work for, except where this is stated explicitly.
Posted on: 29 December 2003 by London Lad
Frank

Thanks

Graham.

Not a lad any longer and not from London!
Posted on: 29 December 2003 by Boekster
You use the better amp for the more important part of the frequency band: Mid's and Hi's. Low end is a bit beyond our hearing, when concerning detail.