Two amps, one set of speakers

hi all, I ask the question on behalf of a friend.
He has a pair of Allaes attached to a NAIT 5si.
He recently got a tube amp, a Synthesis Roma 96DC. He would like to alternate amplifiers without manually connecting and disconnecting.
As a remedy, he found a Dynavox AMP-S which is nothing more than a switch.
The question is: can this device cause damage to the NAIT considering that it is a bit “picky” in the use of speaker cables and therefore consider the Dynavox a load / impedance?

I wouldn’t risk it personally.

1 Like

Leaving aside whether the switch itself may degrade the sound, the primary questions are:

  1. Is it two pole for each channel, so the so-called + & - cables are both switched?
  2. Is it “break before make”, so the two amps are never connected to one another?
  3. Is it non-shorting, so does not short the unused amp output?

If the answer to any of these questions is no, then depending on amp design it could have the potential to damage one or both amps. If all are yes then there is nothing to suggest that the switch would present any risk to the amps.

As for cable, if the cables from the switch to the speakers meet Naim’s inductance and capacitance requirements then then I would expect that to be OK for loading the NAIT. Whether the same cable is optimal for the other amp is another question, but AFAIK most amps are not themselves likely to be damaged by a cable meeting Naim’s spec. I am assuming the cables between amps and switch would be short and therefore negligible even if different from the cables from switch to speakers.

this is the back.
he should use the naim naca 5 for the 5si and the QED 79 strand for the tube.
Naturally, one amplifier will be used at a time as the nait will use the CD as the source and the Roma Synthesis will use the turntable as the source.

I use a Beresford TC7220 Mk II. I have an AV amp and my Nap135s attached, with the speaker cables going to the switch. Then two sets of speakers one set in the main listening room and another set going to the conservatory.

I have had this set up for around 4 years and have had no problems and there is no degradation of sound.

1 Like

IIUC the intent is to have two sets of speaker cables connected, one in use at a time, so one cable carries the signal from switch to speaker and the other goes back to the switch where it is effectively disconnected (swapping over at the switch to change amp & source). The unused connected cable will alter capacitance and inductance, and if they lie alongside each other all the way from switch to speaker that may complicate matters depending upon the construction of the cables, making calculation of capacitance and inductance difficult. I presume there is a reason for wanting a different speaker cable for each amp?

However, that appears to be academic: the pic you posted of the terminals only has connections for one pair of speaker cables if two amps are connected (or you could presumably wire the other way and connect one amp to switch between two pairs speakers)

Speaker cables are Symphony 400 from AV amp into Amp A switch.

Witchhat N2 to switch from Nap135s into Amp B switch.

Linn K20 from switch to conservatory speakers (speaker 1)

NACA5 from switch to main listening room (speaker 2)

I recognize something:

1 Like

Been using this for years now. No degradation in sound and not one problem. SImple solution to people wanting two amps with one speaker

1 Like

And two amps with ability to switch speakers between two rooms!

The K20 with nakamichi banana plugs. Works for 2nd room absolutely fine. Quite a long run from my switch so when I did it I wanted to save some cash on speaker cable!

No. At some point your Friend will blow up something. NO

1 Like

Yup. I have 2x10m which I use when I’d like to experiment with positioning.

1 Like

There should be no issue in the case of the Nait, as there are no problems normally with a solid-state amp open circuit on the output. This is the case when Unitis/SuperNaits are run with NAPs. The one I’d be much more concerned about is the Tube amp - they don’t like open circuits in general and it’s possible to damage the output transformer.

1 Like

Sounds like should be some caution here with tube amp then. They are more sensitive!

I don’t know whether modern tube amps are upset by no load, however if so ideally the switch would change over to a dummy load.

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.