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Is it OK to use an 8 Ohm tubed amp to power 16 Ohm speakers?

There’s a lot of emotion and conflicting answers when I Google this. I have an Air Tight ATM-1s and Zu Audio Druid speakers. The Air Tight is factory-set at 8 Ohms and is switcheable to 16 Ohms but requires removing the base plate and resoldering which I’m reluctant to do — or at least not until listening at the current configuration. Air Tight says it’s fine to have 8 Ohm to 16 Ohm speakers — which I suppose is definitive, but I’m asking the question all the same to this experienced community. Btw, I am not an electrical engineer so please don’t be overly technical in your opionions.

Many thanks.
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almarg's avatar
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almarg
9,670 posts
 
You’ve received many excellent comments above, from particularly knowledgeable members.

I would ask, though, if you are certain about this statement which you made in the initial post:
The Air Tight is factory-set at 8 Ohms and is switcheable to 16 Ohms but requires removing the base plate and resoldering which I’m reluctant to do — or at least not until listening at the current configuration.
Are you sure that it is switchable to 16 ohms, as opposed to (or in addition to) being switchable to 4 ohms? From Stereophile’s review:
The making of loudspeaker connections was only slightly puzzling: Air Tight’s specifications indicate output impedances of 4 and 8 ohms, and the spare but decent instruction manual advises the user to "select the red terminal between 4 ohms and 8 ohms in accordance with the impedance of your loudspeakers"—yet only a single pair of terminals is supplied for each channel, and I found no provisions, inside or out, for switching. In any event, I heard no indications of a mismatch with either my 16-ohm Altec Valencia or my 10-ohm Devore Fidelity Orangutan O/96 speakers.
Also, FWIW, the following is stated in the measurements section of that review, although I’m not sure I agree with the statement that the impedance measurements suggest that the tap is "optimized for a 4 ohm load."
As is usual with a transformer-coupled amplifier using a push-pull pair of EL34 or 6CA7 tubes, the Air Tight’s output impedance was high, ranging from 3.6 ohms at 20Hz to 3.3 ohms at 20kHz. This suggests that the single output-transformer tap is optimized for a 4 ohm load, but it results in response variations of ±1.1dB with the magazine’s standard simulated loudspeaker.
Regards,
-- Al

noromance's avatar
noromance
9,844 posts
 
My Quad ESL57 do not sound good unless I use the 16 ohm tap on my tube amps.
tatyana69
269 posts
 
My recently purchased Proac d80s are 4ohm, which I have never encountered in practice before

I presume that normal 8ohm type amps are all ok to use?

i.e. the reverse of this original thread



bdp24's avatar
bdp24
9,831 posts
 
Modjeski's light-loading recommendation may be based entirely on implementation with his amps. I have found him to be relatively unaware, and uninterested, in what other designers are doing. Interestingly, I found the same to be true of many musical artists---they are so focused on their own art and career that they are unaware of what their contemporaries are doing.
larryi
4,043 posts
 

tatyana,

If you are talking about using tube amps, your circumstance might be a bit more problematic than using a speaker with a higher nominal impedance.  Low impedance speakers tend to be harder to drive and are more prone to having problems with frequency response anomalies when driven by amps with higher output impedances, such as many tube amps. 

That is not to say that your ProAc will not work well with tube amps, you just have to be more careful and accept that some amps will not work well.  I have heard other ProAc speakers, such as the D48, with tube amps and the particular combinations I heard sounded very good. 

The 4 ohm rating of your speaker should be no problem with any decent solid state amp, and given the particular model you have, I am assuming something far better than decent would be used. 

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