Connect Amp With Outdoor Bose 151se's

  • 16 June 2018
  • 5 replies
  • 1699 views

I am using the connect amp with a pair of Bose 151se's which say they are 4/8 ohm compatible. Does anyone know how this works for them to be 4/8 compatible? I read 3.6 ohms across each one, indicating they are 4 ohm. And the Connect Amp needs 8 ohms. My Amp is overheating and i'm trying to eliminate reasons why. My speakers are at the back of my property line with no way to get wires that far, so the Connect Amp is in my shed. I identified that my shed was way above recommended operating temps for the connect, so I put a little window A/C unit in the shed to solve that problem. But through my troubleshooting, it led me to the question on the speaker ohms.

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5 replies

What is the ambient temperature around the amp when it is working? And all Connect Amps run warm/hot when in use, depending on ambient temperatures/ventilation, so why do you conclude yours is over heating?

The Connect Amp is able to drive a pair of 4 ohm speakers, and the Bose are not the problem here. By the way, it is the amp that has to be able to drive the speaker load and therefore be compatible with the speakers; the speakers impedances are just a fact, and speakers don't have to be compatible with the amp in terms of their ohm spec, but have to be so in terms of power they can handle which they draw from the amp.
Deep6Pak,

I’m certainly no expert on this subject, but from the things I have read, 4/8 ohm Speakers, means that the impedance of the speaker moves around with the frequency being output, as most speakers do. It's basically an "8 ohm" speaker but at some frequencies, it's often down around 4 ohms, or even lower.

A 4/8 ohms speaker, in general, often has a higher impedance treble driver, usually around 8 ohms. It also usually has a 4 ohm bass or mid driver, or alternatively the speaker has a pair of 8 ohm bass/mid drivers arranged in parallel. These types of speakers can present themselves quite substantially at 4 ohms impedance to the majority of 'current' that is flowing from the amplifier.

To drive a 4 to 8 ohms speaker, the amplifier specification should really state it is suitable to drive 4 ohms speakers, just to be on the safe side.
These types of speakers can present themselves quite substantially at 4 ohms impedance to the majority of 'current' that is flowing from the amplifier.

A small correction to just the quoted part: the speakers need more current to reproduce lower (usually) frequencies, so they draw more current from the amp by dropping resistance( impedance). The speakers do the pulling of current from the current reservoir that is the amplifier; it isn't the amp that is pushing the current.

And the better designed speakers do less of this, while others can drop impedances to even 2 ohms to increase current draw. But I doubt that this is the problem in this case.
Thanks Kumar for that info... I did go off to look at the tech specs of the Bose 151SE's and the Connect:Amp and I do agree with you that these speakers are well within the capabilities of the Amp.

I think it’s possible that the heat being noticed here by Deep6Pak is possibly the Sonos devices normal working temperature. Digging a little bit further into this, I believe the Connect Amp recommended upper operating temperature should be no more than 40°C or 104°F. So hopefully that will help him to check out if his device is getting too hot, or not.
With even a small window AC running, he should be having ambient temperatures well below 30 celsius, well within the referred operating temperatures. As long as the amp is in a ventilated part of that space, there should be no problem.