A New Wave of Class D Integrated Amplifiers

Kal Rubinson

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May 5, 2010
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Kal - If I use the REW software with a calibrated mic (either the one you suggest or the Drayton one that comes in ML's PBK kit), would you suggest that the mic is pointed towards the speakers or upwards towards the ceiling?

I ask because the Dirac instructions say point upwards, but my results were poor, probably as there's a pendant light above some measurment positions. This causes the left speaker to play louder when the filter is engaged. I hope you'll say it's usually best to point towards the space midway between the speakers. Thanks. Peter
The problem with pointing them towards the speaker is the significance of the speaker's radiation pattern, aiming accuracy and specific goals. The three are interactive.
1. If your goal is purely to fix low frequencies and modal-range EQ, it does not matter how you aim the microphone since LF radiation of most speakers (not panels or dipoles) approaches omnidirectionality as does the directional response of the microphone.
2. If your goal is to extend the EQ above that range (i.e., above the Schroeder or critical frequency), you can aim the mic directly at the speaker with REW and take measurements from one speaker at a time, although the mic is likely to be more directional than your ear(s).
3. With Dirac and many other EQ systems which sweep both/all speakers from each mic position, aiming the speaker upwards provides equal treatment for all the speakers above the critical frequency and is also suitable for all the speakers below the critical frequency.
4. Pointing the mic to the mid-way point between the speakers is possible but I'd suggest you consult John Mulcahy at REW. I've done it to characterize a pair of speakers but not for EQ purposes.
 

Hear Here

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Feb 14, 2020
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Portsmouth, UK
The problem with pointing them towards the speaker is the significance of the speaker's radiation pattern, aiming accuracy and specific goals. The three are interactive.
1. If your goal is purely to fix low frequencies and modal-range EQ, it does not matter how you aim the microphone since LF radiation of most speakers (not panels or dipoles) approaches omnidirectionality as does the directional response of the microphone.
2. If your goal is to extend the EQ above that range (i.e., above the Schroeder or critical frequency), you can aim the mic directly at the speaker with REW and take measurements from one speaker at a time, although the mic is likely to be more directional than your ear(s).
3. With Dirac and many other EQ systems which sweep both/all speakers from each mic position, aiming the speaker upwards provides equal treatment for all the speakers above the critical frequency and is also suitable for all the speakers below the critical frequency.
4. Pointing the mic to the mid-way point between the speakers is possible but I'd suggest you consult John Mulcahy at REW. I've done it to characterize a pair of speakers but not for EQ purposes.
Thanks Kal - all very helpful and logical.

In fact I have 2 EQ options in my present system. Dirac Live in my NAD 33 amp and Avantgarde XD in my Duo speakers.

The former measures the response and provides a visual display of each speaker's performance. It scans the full range but only allows for adjustment below 500 Hz as I haven't bought the full-range upgrade.

The latter doesn't include the response scanning facility but does allow comprehensive adjustments to each active bass speaker's response curve (and crossover type (but I'll stickwith Butterworth 24dB) - so below about 200 Hz. All adjustments have to be judged by one's ears so starting points are difficult to assess.

It's only the bass I'm able to adjust by either system, so your opinion that pointing the mic towards the speakers for bass-only measurement suits me. Thanks for that.

My initial Dirac filter (produced by pointing the NAD-supplied mic upwards as recommended) resulted in poor sound. The obvious problem was the left speaker has become louder - presumably as there's a light fitting above the left side measurements points, possibly affecting 4 of the 9 single-chair readings. Also the bass became rather lightweight, so perhaps it was set on the speakers a bit high.

I've been hesitant in doing more measurements, but perhaps I'll raid the PBK for its calibrated Drayton mic and re-do Dirac, but pointing the mic forward. The resultant response graphs will allow me to make adjustments to the XD speakers and this may avoid the need to engage the Dirac filter altogether - but I'd still have this as an option if it improves the sound.

Many thanks again. Peter
 

Kal Rubinson

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May 5, 2010
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PBK for its calibrated Drayton mic
? Can you access and use the calibration file in DL? I tend to use the Umik-1, OmniMic2 or GoldLine mics rather than the device-provided mics.

BTW, DL up to 500Hz should do it but you might want to pay attention to the choice of target curve.
 

Hear Here

Well-Known Member
Feb 14, 2020
292
121
45
76
Portsmouth, UK
? Can you access and use the calibration file in DL? I tend to use the Umik-1, OmniMic2 or GoldLine mics rather than the device-provided mics.

BTW, DL up to 500Hz should do it but you might want to pay attention to the choice of target curve.
Not sure but I'll check about importing the calibrations. Thanks again. Peter
 

Kal Rubinson

Well-Known Member
May 5, 2010
1,972
332
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NYC/CT
www.stereophile.com
Not sure but I'll check about importing the calibrations. Thanks again. Peter
If you can't import the calibration curve, you can't transfer the "calibrated" mic to the other device.
 
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KyoichiOda

Member
Feb 10, 2021
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Hello everyone, I listened Technics SU-R1000 with following system:
Speakers: Focal Kanta N2
Analog source: Acoustic Arts Player 1 (as CD player)
Digital source: io-data fidata HFAS1-H40 (NAS as music server)

As you know, SU-R1000 works as full digital amplifier for digital input,
with direct conversion from PCM or DSD to PWM.

It sounds very clean, clear and smooth like nice breeze in summer mountain with high resolution.
However mid and bass are thin and light. I recalled the sound of Magnepan.

Digital input from fidata sounds better than analog input, as its resolution and tonality.
In my view it is the best except phono input I didn't listen this time.
 
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