Can anyone help with Alignment?

[Flaesh]

Strange FR.

This is HF144.
XT1464 with another drivers, from VoceCoil:

 

[Robbie010]

Good morning all.

Thank you for all your help with this. Given that the tweeter seems to be a point of contention I did loads of new sweeps this morning. The MDAT is attached, FR graph below for reference.

It seems the tweeter rolls off at 13khz is roughly -6db at 19khz.

I will do the same type of test sweeps on the midrange horn setup later today and then the woofer setup once the new baffle is in place. See where we go from there....

 

[voodooless]

Can you try this, but slightly off-axis?

 

[Robbie010]

At the same distances, 1m, 50cm & 5cm?

What do we call slightly off axis?

Does the Mic still point towards the driver or just point forwards i.e. do I just move the mic up/down, left/right or do I move the mic and angle its line of sight towards the driver?

Sorry for all the questions, I don't want to waste everyone's time by doing the test wrong.........

 

[voodooless]

At the same distances, 1m, 50cm & 5cm?

What do we call slightly off axis?

Does the Mic still point towards the driver or just point forwards i.e. do I just move the mic up/down, left/right or do I move the mic and angle its line of sight towards the driver?

50 cm should be fine, they all look similar. slighly off-axis would be like 5 or 10 deg. Just to see if the phase plug has some effect. You should normally keep pointing the mic towards the driver's center.

Sorry for all the questions, I don't want to waste everyone's time by doing the test wrong.........

Then it's better to ask upfront, right

 

[Robbie010]

Tweeter Off Axis

 

[voodooless]

So, all very similar.

According to this:

VISATON TL16H

Tweeter a tromba 16 mm, 8 Ohm, 200 Wmax

www.dibirama.it

Your result is still strange:

This looks similar to the Visaton datasheet.

 

[Robbie010]

Could it be down to the DAC filter in the Eversolo pre-amp?

 

[voodooless]

Could it be down to the DAC filter in the Eversolo pre-amp?

Well, I ruled that out because the HF144 didn't show a similar dropoff. To be sure: what filter do you use?

 

[Robbie010]

These are the options:

 

[voodooless]

The one selected should be fine.

And if your sample rate is more than 44.1 kHz, it shouldn’t even matter.

 

[Robbie010]

Could it be the Mic?

This is overlaid with the mic calibration:

 

[dualazmak]

As for time alignment among multiple SP-drivers in DSP based multichannel multi-SP-driver multi-amplifier active audio system...

In my case, I evaluated, validated (important!), measured, and applied;

1. Primitive but reliable reproducible "Time-shifted multiple-Fq-tone-bust method";
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493

2. "Multiple-Fq-simultaneous-tone-burst energy-peak matching method";
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494

3. "Single sine-wave matching method";
- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507

In case if you would be seriously interested in applying these methods in your setup, I would be more than happy sharing the test-tone signals I prepared and applied; please simply PM contact me writing your wish.

 

[Keith_W]

Could it be the Mic?

This is overlaid with the mic calibration:

View attachment 479761

Your mic calibration file shows a rising treble response, which means that it is likely to be non-inverted. Cal files may be supplied in inverted or non-inverted format, and measurement software sometimes inverts it for you (REW) or requires you to perform a manual inversion. In other words, your cal file is fine.

Can you please tell us (1) what mic you are using, (2) whether you are pointing it on-axis to the tweeter or straight up, (3) whether you have cal files for horizontal and vertical orientation?

 

[Robbie010]

Your mic calibration file shows a rising treble response, which means that it is likely to be non-inverted. Cal files may be supplied in inverted or non-inverted format, and measurement software sometimes inverts it for you (REW) or requires you to perform a manual inversion. In other words, your cal file is fine.

Can you please tell us (1) what mic you are using, (2) whether you are pointing it on-axis to the tweeter or straight up, (3) whether you have cal files for horizontal and vertical orientation?

The mic is Umik 2.

Measurements were taken with mic pointed at the driver with 0 degree cal file loaded.

I also have the 90 degree cal file.

 

[Keith_W]

Okay, in that case it appears that you are taking measurements correctly. So something is faulty - either it's your mic, or both tweeters. The next diagnostic step is to do borrow a mic and measure those tweeters. If that really is the frequency response, then write to the manufacturer asking them why the measured performance does not match the data sheet.

 

[Robbie010]

I'll need to get another mic from somewhere.

I just tried factory re-setting the DSP Crossover as a test, I ran the sweep again and no change.

I then bypassed the DSP crossover entirely and directly connected the pre-amp to the power amp, no change.

Finally, I tried running the sweep via REW on my MAC, rather than my windows PC, no change.

That only leaves the pre-amp, the power amp of the mic.

I do have another little Class D power amp here that I can wire up to test.

 

[Robbie010]

Just tested the the power amp theory, no change.

So that just leaves the Eversolo pre-amp/DAC or the mic.

 

[voodooless]

You could just choose to ignore it for now… did you load the microphone calibration file?

Plenty of other stuff to worry about.

 

[Robbie010]

Yes, I think I’ll need to until I can borrow another mic and/or preamp.