Dr. Klaus Heinz of HEDD Audio (ex ADAM Audio) - measuring speakers, in particular speaker dynamics

[tuga]

You asserted the lack of low level measurements. Make up your mind.

See above. I meant distortion when reproducing low-level signals as opposed to the usual ≥ 90 dB measurements.

 

[SIY]

See above. I meant distortion when reproducing low-level signals as opposed to the usual ≥ 90 dB measurements.

The limit there is room noise floor. If your room is really quiet, it might be at 25-30 dBSPL. So if you run the speakers at, say, 50 dB, you’re limited to 10% as the measurement floor. Doable, but not useful.

GedLee metric and similar measures are a better way since they’re weighted heavily towards the area near zero crossing.

 

[tuga]

The limit there is room noise floor. If your room is really quiet, it might be at 25-30 dBSPL. So if you run the speakers at, say, 50 dB, you’re limited to 10% as the measurement floor. Doable, but not useful.

GedLee metric and similar measures are a better way since they’re weighted heavily towards the area near zero crossing.

I live in a quiet residential area and the noise-floor on a windless day is just over 40dB still.

By not useful do you mean that the S/N ration would be too low to reveal distortion? If so, what if the measurements are made in an anechoic room?

I will try to inform myself on the GedLee metric. Cheers.

 

[andreasmaaan]

The limit there is room noise floor. If your room is really quiet, it might be at 25-30 dBSPL. So if you run the speakers at, say, 50 dB, you’re limited to 10% as the measurement floor. Doable, but not useful.

It is possible to measure distortion somewhat below the ambient noise floor, though. And, at least in the case of transducers, it’s possible (and preferable for most purposes IMO) to measure at distances below 1m, which increases the SNR.

Having said that, I can’t speak for @tuga, but when I said “low-level”, I had in mind levels more in the 65-85dB range, which represent average SPLs for moderate-level listening, or peak SPLs for quiet listening. Basically, i had in mind SPLs below the more commonly measured 90 to 100dB/1m.

I agree there’s generally not much point measuring at such low levels that it’s difficult to separate distortion from noise (e.g. 50dB/1m): if our instruments struggle to do this, our ears certainly will, too.

 

[SIY]

It is possible to measure distortion somewhat below the ambient noise floor, though. And, at least in the case of transducers, it’s possible (and preferable for most purposes IMO) to measure at distances below 1m, which increases the SNR.

Having said that, I can’t speak for @tuga, but when I said “low-level”, I had in mind levels more in the 65-85dB range, which represent the average SPL for moderate-level listening, or peak SPL for quiet listening. Basically anything below the more commonly measured 90 to 100dB/1m.

I agree there’s generally not much point measuring at such low levels that it’s difficult to separate distortion from noise: if our instruments struggle to do this, our ears certainly will, too.

I don’t know about every reviewer, but all my speaker reviews have measurements at lower SPLs.

Unsurprisingly, distortion nearly always reduces with level.

 

[andreasmaaan]

I don’t know about every reviewer, but all my speaker reviews have measurements at lower SPLs.

Which in particular? Of all the online sources I’m familiar with that publish loudspeaker distortion measurements, Amir’s 86dB/1m is the lowest SPL measurement I’m aware of.

Unsurprisingly, distortion nearly always reduces with level.

I can’t disagree with that in general

The thing is IME that symmetrical transducer nonlinearities tend to produce distortions that do not change significantly with level. So, a speaker’s THD may appear to be quite low at say 96dB/1m (which is the lowest SPL at which Soundstage takes distortion measurements), even though its odd-order distortion at 80dB/1m is just as high in the midrange as it is at 96dB/1m.

 

[tuga]

Unsurprisingly, distortion nearly always reduces with level.

Where can I find your measurements?

Unsurprisingly, distortion nearly always reduces with level.

I was thinking very low-levels, where the diaphragm displacement is slight.

 

[SIY]

Which in particular? Of all the online sources I’m familiar with that publish loudspeaker distortion measurements, Amir’s 86dB/1m is the lowest SPL measurement I’m aware of.



I can’t disagree with that in general

The thing is IME that symmetrical transducer nonlinearities tend to produce distortions that do not change significantly with level. So, a speaker’s THD may appear to be quite low at say 96dB/1m (which is the lowest SPL at which Soundstage takes distortion measurements), even though its odd-order distortion at 80dB/1m is just as high in the midrange as it is at 96dB/1m.

I do them for print, not online. But certainly you subscribe to AudioXpress, right? RIGHT?

 

[andreasmaaan]

I do them for print, not online. But certainly you subscribe to AudioXpress, right? RIGHT?

Haha. TBH, I subscribe to Voice Coil (mostly for the transducer measurements and new patent updates) but not the print edition of Audioxpress... Should I?

And on a more serious note, how are the shipping and taxes on it in Europe? Or is there a distributor here? I’d def be interested.