H8000FW Unusual crackling noise only on DSP#2 Analog out.

[TubeAmpNut]

I recently acquired a H8000FW that exhibits strange noise only on the analog outs and DSP#2.  It almost sounds as if there is a dedicated DAC for DSP#2 that has a bad clock reference (I would think the DAC is on the mixer not the DSP).

I made a little video to demonstrate the issue:  https://youtu.be/-uVDVKlrEwU

Both DSP#1 and #2 are on patch 9010-TF Digital delay.  100% H8000FW with 47% internal mix.

 

The routing is in the following order:

 

1. Analog in — DSP#1 — Analog out (clean)

2. Analog in — DSP#1 — AES out (clean)

3. Analog in — DSP#2 — Analog out (**digital crackling**) You can even hear a slight crackle at start.

4. Analog in — DSP#2 — AES out (clean)

5. AES in — DSP#2 — Analog out (**digital crackling**)

6. AES in — DSP#2 — AES out (clean)

7. AES in — DSP#1 — Analog out (clean)

I have run through every internal diagnostic without any errors, I have also performed a re-install of the latest firmware (5.6.1).

 

If this noise were on the analog out for both DSP’s, I’d be certain it were an analog output board issue.  What stumps me is it only occurs on DSP#2.

 

Any ideas?  Time for an RMA?

[nickrose]

It sounds as though there is a fault in the routing engine. Probably has to come back.

Does it vary with different presets ?

Do you get it on DSP bypass ?

Does it occur on all analog outputs when driven from DSP 2 ?

 

[nickrose]

Changing U501 might help. This is a surface mount part, so not for everyone.

If U500 is socketed, it might be worth wiggling it in the socket in case of bad contacts.

But, it probably has to come back.

 

[TubeAmpNut]

Thank you for the prompt reply,

Testing on a few 8 channel presets, as well as the “Thru” preset, the crackles are on all 8 DSP#2 channels and both analog out pairs 1/2 & 3/4

I should add I also tried all internal clock rates as well as wordclock at 48K.

Bypassing machine B does not remediate the issue, only using the digital outs does

Is a routing engine repair a complicated/time consuming one?  Does it require major motherboard fixes?

thanks,

BK

 

nickrose wrote:

It sounds as though there is a fault in the routing engine. Probably has to come back.

Does it vary with different presets ?

Do you get it on DSP bypass ?

Does it occur on all analog outputs when driven from DSP 2 ?

[Author]

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