Pre3 Driving 3 amps?

[david]

Hi,
My Pre 3 seems very happy driving two amps at the moment, with the phono outputs paralleled. Is there any reason why it might be less happy driving 3 outputs?

And has anyone used those Phono splitters? If so, do they work with no loss of sound quality if decent quality?

Thanks
David

[Richard]

Hi David,

I'm assuming you are passive bi-amped at the mo using bi/tri wired speakers and are looking to go passive tri-amp using tri-wire speakers.

Pre3 has a very low output impedance of around 12 ohms iirc so will drive most loads easily. It will see the amps paralleled as a combined load so if they are all 100K it will see 33K and if the cables/inputs are 120pF each it will see 360pF etc.

Good splitters shouldn't make any difference at audio frequencies but you could always swap them between amp connections to see if you can hear anything.

The amps themselves will all see a common source and so will still be individually affected by your choice of cables and cable capacitance. Pre will see a combined load as said so if it is too low or combined capacitance is too high f response may suffer.

So I would use 3 amps of same or adjustable sensitivity and high'ish impedance around 100K (perhaps not 20K as some modern ss amps are) and cable them up with similar low cap cables, at least as a starting point.

You won't do any harm trying different amps and cables but it's good to be aware of what may be happening and if you can check audio f response with Pre and 3 amps connected with their cables and splitters it would be ideal.

[david]

Hi Richard,
The amps are actually a: 300b push pull with around 100k input impedance, a Roksan Kandy around 20k input impedance, and a Rel sub probably around 20k too.

So the Pre 3 will see less than 10k resistance. I guess I will try it and see.

This layout works with evryday listening thru the Roksan + sub. When we want a real listen, we switch off but don't disconnect the Roksan, and listen thru the 300b push pull + sub.
David

[Richard]

Hi David, ok give it a go it won't hurt anything

[John Caswell]

Hi David,
Pre III has an output impedance of about 10R so will drive pretty well any highish impedance (above 2K) to distraction.
The only problem I see is if he sensitivities of the units are drastically different in which case you may have to fit attenuators to the higher sensitivity amplifiers.
Suck it and see.

John