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morleyc
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Jul 5, 2021

4 x 125W speakers from 600W amp

Dear all, I currently have 2 x DM6SE (125W 8 ohm) speakers wired in parallel back to a P2600A 600w per channel amp (the other channel i am using for another zone) for my home background music setup.

 

I would like to expand out the coverage with an additional 2 matching speakers, to wire in two parallel pairs - this would give a total of 500watts being driven by 600watts, into what is seen as 8 ohms (8+8/2) by the amp i believe.

 

Are there any issues with this, or do I not have enough headroom on the amp?

 

The specs of speakers and amps are below:

 

https://pro.bose.com/en_us/products/loudspeakers/background_foreground/designmax/designmax_dm6se.htm...

 

https://pro.bose.com/en_us/products/amplifiers/powerspace/powerspace_p2600A.html

 

It is possible to switch from low-impedance to high-impedance line voltage mode on the speakers and amp, if that were to make any difference.

 

Thanks in advance for the advice.

1 ACCEPTED SOLUTION

Accepted Solutions
NickD-at-Bose
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Feb 7, 2017

Re: 4 x 125W speakers from 600W amp

Author Accepted Answer selected by morleyc

Given the amp is 600w, and the transformer tapping on the speakers can be set to 80W at 70V, that would give 4 x 80W = 320W. I presume you can go up to as many speakers within the output of the amp (or some limit thereof ~80%?).

Yes, that's correct. Depending on how you will be using the system, you can elect to provide more or less headroom. For standard musical program playback, 5-10% head room is appropriate.

 

Specifically would like to understand how we seem to be able to drive more speakers using HZ than LZ - I will dig that out from the links if you can kindly point me in the right direction.

The answer to this has to do with how a high-z (high impedance) loudspeaker system works. Basically, there are transformers on either end. The amplifier's transformer normalizes the output voltage to 70VRMS, and the loudspeaker's transformer steps it down with tap settings that have a higher and different impedance with each setting. This varying impedance together with the normalized voltage allow a calculated RMS power to pass to the loudspeaker. You simply add the cumulative tap settings of the loudspeakers together to calculate the total power draw. So long as you don't exceed the 70V power rating of the amplifier, your system will work well.

 

There are several resources to learn more about 70V distributed systems. An internet search will yield lots of results. As for a system design tool, click here.

 

Nick

 

View solution in original post

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NickD-at-Bose
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Feb 7, 2017

Re: 4 x 125W speakers from 600W amp

Hi there, your best option here would be change each loudspeaker to the 70V input (requires re-wiring the phoenix block), and changing the amplifier to HIGH-Z for that channel.

morleyc
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Jul 5, 2021

Re: 4 x 125W speakers from 600W amp

Many thanks @NickD-at-Bose

 

Given the amp is 600w, and the transformer tapping on the speakers can be set to 80W at 70V, that would give 4 x 80W = 320W. I presume you can go up to as many speakers within the output of the amp (or some limit thereof ~80%?).

 

Above anything, I don't want to damage the speaker or the amp, but 320W from 600W sounds like decent buffer and not driving anything to the max.

 

Sorry to ask, any links to design guides or calculators would be appreciated just for my own learning so I don't need to bug others.

 

Specifically would like to understand how we seem to be able to drive more speakers using HZ than LZ - I will dig that out from the links if you can kindly point me in the right direction.

 

Many thanks for the time.

NickD-at-Bose
Bose Employee
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Registered since

Feb 7, 2017

Re: 4 x 125W speakers from 600W amp

Author Accepted Answer selected by morleyc

Given the amp is 600w, and the transformer tapping on the speakers can be set to 80W at 70V, that would give 4 x 80W = 320W. I presume you can go up to as many speakers within the output of the amp (or some limit thereof ~80%?).

Yes, that's correct. Depending on how you will be using the system, you can elect to provide more or less headroom. For standard musical program playback, 5-10% head room is appropriate.

 

Specifically would like to understand how we seem to be able to drive more speakers using HZ than LZ - I will dig that out from the links if you can kindly point me in the right direction.

The answer to this has to do with how a high-z (high impedance) loudspeaker system works. Basically, there are transformers on either end. The amplifier's transformer normalizes the output voltage to 70VRMS, and the loudspeaker's transformer steps it down with tap settings that have a higher and different impedance with each setting. This varying impedance together with the normalized voltage allow a calculated RMS power to pass to the loudspeaker. You simply add the cumulative tap settings of the loudspeakers together to calculate the total power draw. So long as you don't exceed the 70V power rating of the amplifier, your system will work well.

 

There are several resources to learn more about 70V distributed systems. An internet search will yield lots of results. As for a system design tool, click here.

 

Nick

 

View solution in original post

morleyc
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Jul 5, 2021

Re: 4 x 125W speakers from 600W amp

Amazing products and even more amazing support - thank you NickD for the patience and detail in response, greatly appreciated and BOSE fan for life.