UMIK-1 arrived

[slartibartfast]

Nothing wrong with that.

The term "phase" usually describes a variation in timing relative to a full 360⁰ sine wave. The 0⁰/180⁰ "phase" switch is actually a bit of a misnomer because it doesn't shift anything in the time domain. It just inverts the polarity (or "absolute phase") of the signal.

Surprisingly, quite a number of amplifiers do not preserve the absolute phase and human beings are usually not sensitive to it. However, if you combine two separately amplified sources (like e.g. a sub and an amp with passive speakers or a a pair of active speakers) you should always check which polarity results in clean summation with no dips.

0⁰ or 180⁰, it doesn't really matter as.long as.the outcome is OK

I wonder if the WiiM Amp preserves absolute phase. I get a better result with the sub output switched to 180 degrees but I actually use a delay of 6ms which is half a cycle at 80Hz. I wonder if I should use 180 degrees instead.

 

[EddNog]

I wonder if the WiiM Amp preserves absolute phase. I get a better result with the sub output switched to 180 degrees but I actually use a delay of 6ms which is half a cycle at 80Hz. I wonder if I should use 180 degrees instead.

Nothing wrong with doing this.

The SVS subs, in fact, have phase adjustment in 1-degree granular increments, from 0-180 degrees, and then a separate polarity toggle, so it really covers anywhere from 0-360 degrees in single degree increments. There have been scenarios (before I bought a miniDSP) where I even had to turn on the 180 degree toggle and then add some additional phase on top of that, effectively going past 210 degrees.

-Ed

 

[harkpabst]

I wonder if the WiiM Amp preserves absolute phase. I get a better result with the sub output switched to 180 degrees but I actually use a delay of 6ms which is half a cycle at 80Hz. I wonder if I should use 180 degrees instead.

I never tested this but @dominikz found out that the WiiM Amp Pro currently inverts the phase at the speaker terminals (but not the subwoofer output).

My pragmatic approach would be to try either polarity and see which requires the lesser amount of delay for perfect acoustical summation.

 

[slartibartfast]

I never tested this but @dominikz found out that the WiiM Amp Pro currently inverts the phase at the speaker terminals (but not the subwoofer output).

My pragmatic approach would be to try either polarity and see which requires the lesser amount of delay for perfect acoustical summation.

Interesting, that would make sense. It would explain why I need a 6ms delay when the sub is sitting right next to the right speaker.

 

[EddNog]

Interesting, that would make sense. It would explain why I need a 6ms delay when the sub is sitting right next to the right speaker.

Any subwoofer that has DSP also has its own inherent delay/lag. On average, SVS subs with DSP suffer an additional ~7.4ms delay. KEF subs with DSP also have some degree of lag, etc. Should expect this with WiiM Sub Pro too.

-Ed

 

[slartibartfast]

Any subwoofer that has DSP also has its own inherent delay/lag. On average, SVS subs with DSP suffer an additional ~7.4ms delay. KEF subs with DSP also have some degree of lag, etc. Should expect this with WiiM Sub Pro too.

-Ed

My BK XLS200 doesn't have any DSP though which is why the 6ms always bothered me.

 

[harkpabst]

There are still some purely analogue subwoofers, like e.g. the entire BK Electronics range.

Edit: Too late ...

 

[EddNog]

My BK XLS200 doesn't have any DSP though which is why the 6ms always bothered me.

There are still some purely analogue subwoofers, like e.g. the entire BK Electronics range.

Edit: Too late ...

Honestly, had my budget allowed it, I would've preferred servo-controlled subs through my entire system, but that was WAY beyond the realm of affordability for me. Almost impossible to find Rythmik subs in the secondary market, and prices for new units, especially now in the age of tariffs driven by the asshole you couldn't have paid me to vote for, is truly prohibitive. I got all of my subs either refurb or open-box (minimum one-year if not full manufacturer's warrantied), which is very easy to find with SVS.

-Ed

 

[slartibartfast]

I never tested this but @dominikz found out that the WiiM Amp Pro currently inverts the phase at the speaker terminals (but not the subwoofer output).

My pragmatic approach would be to try either polarity and see which requires the lesser amount of delay for perfect acoustical summation.

This thread from ASR mentions better results with the sub output inverted.

Time align with Wiim amp using Rew

Yes, I used one channel only. I made the choice without any expectation that it makes much of a difference. Left channel is nearer to the door, so I figured it might have slightly less room reinforcement in the low frequencies, so I preferred that one for that reason, assuming that either gain...

www.audiosciencereview.com

 

[harkpabst]

Still, I wouldn't go by other buyers' experience. You never know what's different in their setup. The amp built into a certain sub could also invert the case. By (careless) design.

Or - even worse - some trainee might have mixed up the polarity when connecting the woofer on his side of the workshop desk while his pal on the other side did it right.

Yes, 100% QA would detect such errors in theory, if this check is part of the routine. In mtiway loudspeakers it is often necessary to invert the polarity of one or more drivers. Usually this is dealt with by connecting the cables out of phase at the crossover, so trainees assembling the speakers don't have to think about it, but you never know.

The first batch of Fosi V3 Mono amps (those obtained throug Kickstarter) came with inverted polarity, which was corrected during series production. Imagine a pair of monoblocks being ripped apart for other use cases and later paired with single units from a different batch.

And finally such behaviour might even be changeable through software with digital devices ...

Long story short: Better trust your own measurements, especially if you've already experienced strange behaviour.