Phase control.....no effect?

[brijenjas]

Hi, I've been lurking here for awhile, some good reading.

I bought an eD A3-300 around 3 weeks ago and though I'd measure it'd response.

I did have a bit of trouble getting my sound card calibrated, but I pretty sure I finally got it.

Although the sub sounds very good with movies and music, according the graph I have a dip in the high 30's and a huge peak in th 40's.

I thought (probably mistakenly) that the phase control would change the response somewhat, but no matter where I set it , no change.

Should the phase control have an effect on the response, or does it just have to do with phase as related to the other speakers?

Thanks.

[Otto]

Hey there,

What's your crossover point? I'd expect to see the most change around that area.

Is there perhaps a "bypass" switch for the phase control?

I don't have a phase control myself, but I can invert phase (180 degree shift), and I measure a difference. I would expect that you should at least see some minor changes. When using REW, you can overlay all your measurements on one set of axes; it's much easier to see differences that way. Just select "All Measured" on the tabs across the top of the measurement display.

[brucek]

Should the phase control have an effect on the response, or does it just have to do with phase as related to the other speakers?

Yeah, you'll only notice phase changes in the sub in relation to the mains. It becomes apparant around the crossover area when you play both the sub and mains. Try a measurement with both on and you'll see a difference.

Anyway, you should be sure to set the target level to 75dB when you set up REW. You're measuring way too low. The left panel of REW where it says Set Target Level - that's actually a button. Once you have set the SPL level with your meter to 75dB at the listening position, then Calibrate the REW SPL meter to 75dB and then Set Target Level to 75dB, then measure...

brucek

[brijenjas]

Crossover at 70.

No bypass for phase, variable from 0 to 180.

Thanks for that info about the overlay, I was looking for that option, but looked in the wrong places.

REW has a bit of a learning curve for us noobs new to measuring.

I'll do some more testing later this week.

[Otto]

Oops, I guess I wasn't thinking straight last night. brucek is right -- you have to measure with mains on at the same time.

[Wayne A. Pflughaupt]

What brucek said:

brucek wrote:

Yeah, you'll only notice phase changes in the sub in relation to the mains. It becomes apparant around the crossover area when you play both the sub and mains.

To elaborate a little, an octave or so above and below the crossover point, if there are phase-related response issues. My experience has been that response will look real ragged there, with sharp peaks and depressions.

In your situation, the response problems you’re having are far too broad, and/or pretty well too low to be phase-related.

Regards,
Wayne

[brijenjas]

Thanks for the input guys.

I thought I was testing at 75db, but looking at the graph I see I wasn't.

I'll do as brucek suggested and recalibrate and run it again.