Is it okay to run two amplifiers for two speakers


I have a Nakamichi CA- 7 preamp that has two sets of line outputs. So I use two Nakamichi PA-7aii's per channel with one speaker for each amp. It sounds better. The amp does not have a mono switch. The instructions for the CA-7 preamp: This unit provides two sets of line outputs, so two power amplifiers can be driven simultaneously, if desired. Since exactly the same signal is supplied at these outputs, either set can be chosen when only one power amplifier is used. It doesn't say anything about the speaker connection. Your thoughts? Thanks.

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You may never connect the active outputs of an amplifier together. Even a tiny voltage difference can cause large and damaging current flows.

What you can do is bi-amp a speaker which has two separate binding posts IF the binding posts themselves are not internally connected.

If your amplifier is fully balanced AND you want to bi-amp a speaker you must check that there’s no continuity between speaker grounds or hots. For most amps just making sure the hots have infinite impedance is enough.

You may never connect the active outputs of an amplifier together.

 

To clarify this statement, I mean directly together such as via a speaker cable or even an accidental strand that shorts from one to the other.  However, in cases when the amp is bridged and :

  • there is a speaker in between the two (+) terminals
  • The speaker between the terminals equals or exceeds the minimum bridged impedance

it's OK to do so.

Don’t confuse bridging with biamping. Biamping is using the two channels on a stereo amp to run one speaker by connecting one channel to the bass and the other to the treble/midrange if the speaker is set up to do that. It has minimal effect other than to take some load off of the amp.

Bridging is using a stereo amplifier as a monoblock by using both channels to drive a single speaker (not biamped). But this is dangerous unless you know the amp is made to be bridged and you know how to set it up to do that.

ALSO, with bridging, you need to look at the speaker specs. You should not bridge into a 4 ohm speaker because the load on the amp is effectively 2 ohms which will blow many amps. If the amp is stable to a 2 ohm load then it may be OK.

I have a PA-7...it is a pretty powerful amp. I don’t think you need to use both unless your speakers are huge power hogs. Suggest you not bridge but you can consider biamping just to keep the gear in use, but it won’t have a major impact. Active biamping is different, but takes technical work - not recommended for the your average music fan.