Review of DJ equipment?

[nagster]

These are measurement results for the AlphaTheta / CDJ-3000X.
There are a lot of them, so I'll only post a few. DJ equipment has too many variables.
This is an AP dashboard with a 997Hz / 0 dBFS sine wave and intersample peak test signal.
From what I saw, the response was similar when the tempo reset function was enabled and when the tempo slider was set to 0 %.

The Pioneer logo appears to be gone.
The screen is fast, vivid, and easy to read with no afterimages.
File operations and scrolling are very quick.
The response of each button was also direct.
I can't evaluate the DJ play functions.
Wired and wireless LAN are built-in.
It is advertised as being capable of streaming music from the cloud.
These days, DJs may be touring empty-handed, without even a USB stick.

CDJ-3000X - Next-generation professional DJ player - AlphaTheta

The CDJ-3000X offers speedy access to online music, and the “X” in its name embodies multiple meanings: transformation in the evolution of media, expanded connectivity with various devices and platforms, and extraordinary reliability and sound quality that surpasses the CDJ-3000.

alphatheta.com

 

[nagster]

I don't have access to a CDJ right now, but from what I remember, it was as follows:
44.1 kHz source -> 44.1 kHz coaxial output
48/88.2/96 kHz source -> 96 kHz coaxial output

I can only guess at the sampling frequency of the DAC section, but I will check the coaxial output again next time.

This is about the sampling frequency of the digital output of AlphaTheta / CDJ-3000X.
TEMPO slider is 0 % and MASTER TEMPO is OFF.
The CDJ-3000X's digital output was 96 kHz for 44.1 / 48 / 88.2 / 96 kHz sources.
The CDJ-2000NXS2's digital output was 44.1 kHz for 44.1 kHz sources and 96 kHz for 48 / 88.2 / 96 kHz sources.

 

[nagster]

This is the frequency response, J-test, and 32-tone of the AlphaTheta / CDJ-3000X.
The 32-tone measurement results were so bad that I repeated them several times, but the results were the same. This may be due to measurement artifacts.
That's all for now.

edit: Added explanation to 32-tone screenshots

 

[naagratrax]

Wtf is that big hole in the frequency response at 2KHZ ? It's horrible

I'm semi professional DJ and don't know that the master tempo impact the sound quality so much

Can you try with others players ? Like the Denon SC6000

 

[Reticuli]

Can you try with others players ? Like the Denon SC6000

See my prior post for RMAA of old Pioneer, Hanpin, Gemini, and new Denon over SPDIF. Not a full-on audio analyzer, but useful for comparison of the ones I looked at.

***
Odd that there appears to be little to no pad on the audio processed by the CDJ-3000 and X, because I believe it was Pulse that told me they had the necessary headroom already built into the processing to prevent intersample peaks. We got a substantial pad put into the firmware of the Denon DJ Prime series standalone players pretty early on to prevent this issue based on my recommendation, and previous to that we learned there was an omnipotent lookahead limiter that was in there to prevent any form of clipping in the player processing from the SRC, speed change, and key change... though obviously it was causing some additional roll off and limiting beyond the crude anti-aliasing filter. So, the pad added to the Prime playback later should have simply prevented the playback limiter from being utilized. On the Prime mixers, we also have the ability to disable both the FX and Master limiters, as well as change the mixer sample rate to 44.1, 48, or 96khz.

On the topic of SPDIF vs analog output on the Prime players, I'm still not certain if the former is fed the same exact data stream as the latter. A number of users have told me they don't believe that's the case based on their own ears. The AKM 4413 DAC is capable of much higher sampling rate than the 96khz the Prime SPDIF is set to.

 

[nagster]

Wtf is that big hole in the frequency response at 2KHZ ? It's horrible
I'm semi professional DJ and don't know that the master tempo impact the sound quality so much

The same thing happened with the CDJ-3000, but it's a shame that it hasn't been improved. (The overload issue, too.)

One thing I forgot to mention above is that the SD card slot has been changed to USB-C (host). SD cards have the advantage of being physically less likely to break, but having more USB ports might be more convenient. (The person who lent me the CDJ told me that one time, during a DJ change, a USB stick broke, stopping the sound, and they couldn't remove the remains of the connector, causing panic onstage.)

Can you try with others players ? Like the Denon SC6000

If I ever get access to a Denon DJ player I'll definitely measurement it out.

 

[kidprofessor]

This is really late in the game, but when the Pioneer CDJ decks were around they were considered, by far, the best.

It would be interesting to try one, play with the pitch controls especially since they were always said to be inferior to those on turntables.

I DJed for years and used CDJs a couple times. The pitch control isn’t inferior, but when you’re beat matching fast, it’s easier to manipulate the speed of a standard Tech 12 by brushing the side or turning the spindle

 

[Reticuli]

I can confirm the SC Prime player separates analog outputs measure similarly in RMAA to the digital outs. Same treble roll off. Same aliasing distortion causing the IMD hump that shows about 100X the original test signal's IMD + noise. I am inquiring on whether the analog outputs get the same data stream as the digital outputs, but them seem pretty similar. If the audio streams to both the DACs and SPDIF are the same all the time in the firmware, then obviously there's no advantage to using the analog outputs into a 96khz digital DJ mixer that has digital inputs. Here are the analog outputs with a 24/96 RMAA test wav file, pitch fader at zero, key lock off into a Tascam 366 set to 24/192:

 

[Reticuli]

More SC Prime player separates graphs of the analog outs, this time generated by Chat GPT:

"HF rolloff
raised noise
ultrasonic imaging spike
spectral time-domain smearing
loss of detail

Evidence of zero stuffing SRC, polyphase FIR resampler leakage, or imperfect anti-imaging filters. Possibly DSP running at only 48khz even with higher rate content, and the data stream could then be poorly upsampled to 96khz for marketing reasons at the SPDIF"

InMusic says these run at 96khz internally, but it looks like a 48khz data stream to the analog outputs even with 96khz files, and the SPDIF has nothing useful above 24khz except added noise. Actually, roll off begins at about 12khz.