Strange issue with Pioneer Equipment

[HiddenAgenda]

I have a Technics SL1210 turntable, Nagaoka MP-110 and a Pioneer DJM 400 mixer/amp, focusrite scarlett soundcard

When recording a vinyl I noticed something odd in the spectrograph (Spek) which I use to ensure the recording is truly 96kHz shows that the signal from the DJM400 seems to peak at 38kHz

I pulled out a rip I had done months earlier using the same setup but instead of the DJM400 I had a numark DJ mixer.

Same track:
Numark

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Pioneer DJM400:

An externally hosted image should be here but it was not working when we last tested it.

Direct from SL1210 into Focusrite (RIAA curve applied in audacity and amplified 38db):

An externally hosted image should be here but it was not working when we last tested it.

To me it seems the pioneer phono stage is so bad it is not hitting the signal that I was getting with the numark mixer.

I was going to buy this to temp solve the issue until I can buy a new mixer that I can trust:

Pro-Ject Phono Box MM Amplifier - Black: Amazon.co.uk: Electronics

 

[Xoc1]

If the 3rd spectrograph is the most accurate representation of what to expect then the Numark seems to be over emphasising the ultrasonic while the Pioneer is filtering it out.
I am more concerned about the constant signal at approx. 33Khz with the Pioneer spectrograph - does this infer that the pioneer is oscillating ?

 

[JonSnell Electronic]

The audio spectrum for our ears stops at best at 18kHZ. Why allow any clocking and harmonics above this?
Filter it out and that stops instability.

 

[HiddenAgenda]

The audio spectrum for our ears stops at best at 18kHZ. Why allow any clocking and harmonics above this?
Filter it out and that stops instability.

I do take your point but if it's "there" (i.e. I can see "it" in all 3 recordings above 18kHz) then why not include it when taking a master recording? Space isn't an issue.

When I convert down to 16bit 48kHz wav for listening I may not be hearing the extra but may aswell I figure.

 

[HiddenAgenda]

If the 3rd spectrograph is the most accurate representation of what to expect then the Numark seems to be over emphasising the ultrasonic while the Pioneer is filtering it out.
I am more concerned about the constant signal at approx. 33Khz with the Pioneer spectrograph - does this infer that the pioneer is oscillating ?

Yes there is a electrical hum somewhere the problem is here I cannot hear it until I record silence and normalise the recording to hear (and see) the hum. Bearing in mind its came in at -89db and I cannot hear it during playback on any tests.

Pioneer utterly useles piece of kit I was warned about their poor phono inputs.

** Edit I just tried pulling various cables in and out, turning various knobs up and down/off and on and the hum is constant on spectrograph (until you plug out the turntable obvs from the mixer but thats pointless).

No such issue with the numark so im blaming the Pioneer. Utter rubbish

Im almost on the verge of buying a Rega Fono Mini A2D Phono Pre-Amplifier but really id rather have a dj mixer which has good phono connections. I have heard allan & heath are very good.