• Registered: 2023-10-17
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Topic: [Solved] Issues with new Topping A70 Pro amp

All,

I just received a Topping A70 Pro amp and have hooked it up to the RME ADI-2 DAC fs using both SE and XLR. I have DC Protection set to "filter" and have the volume on the RME set to -20 dBr. Gain on amp is set to low and volume -30. This happens regardless of SE or XLR inputs used. The amp routinely switches the sound off temporarily using a relay.  When I tried my iPhone as an input direct to the amp, it played just fine. This makes me think maybe the issue is on the RME end? I've asked on AudioScienceReview forum and they provided me with some help but I haven't been able to solve teh problem yet. Any thoughts?

Link for reference: https://www.audiosciencereview.com/foru … st-1782405

2 Reply by KaiS (edited by KaiS 2023-11-22 15:04:00)

  • KaiS
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Re: [Solved] Issues with new Topping A70 Pro amp

Check with ADI-2’s PEQ preset “Rumble Filter” or just a HPF set to 20 Hz.
This removes all DC and subsonics that might trigger protection.

Does the problem persist?

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  • Registered: 2023-10-17
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Re: [Solved] Issues with new Topping A70 Pro amp

I put in a -12dB low shelf (q=0.9, f = 20hZ). This seemed to reduce the frequency of cutouts, but not eliminate them. If I raise the volume on the RME above the -20 to say -10, it cuts out even more frequently. Driving the amp with another DAC has had no cut outs. I also have the DC Protection set to "Filter" which is supposed to start reducing output at 7Hz and completely eliminate it by 0Hz. Is the Rumble Filter over kill?

4 Reply by KaiS (edited by KaiS 2023-11-22 16:01:41)

  • KaiS
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Re: [Solved] Issues with new Topping A70 Pro amp

antagron wrote:

I put in a -12dB low shelf (q=0.9, f = 20hZ). …
..I also have the DC Protection set to "Filter" which is supposed to start reducing output at 7Hz and completely eliminate it by 0Hz. Is the Rumble Filter over kill?

It‘s just for clearly isolating the source of the problem, not for everyday use.

Use a High Pass (= Lo Cut) - Filter.
A Shelf-Filter is the wrong tool.

7 Hz might be too low, leaving too much subsonics, in case those are responsible.

antagron wrote:

… If I raise the volume on the RME above the -20 to say -10, it cuts out even more frequently. Driving the amp with another DAC has had no cut outs.

What if you set ADI-2‘s output to about the same loudness as  “the other“ DAC?

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  • Registered: 2023-10-17
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Re: [Solved] Issues with new Topping A70 Pro amp

OK! I didn't appreciate the distinction, now I'm using Band 1 High Pass, -12dB @ 20Hz, q=0.8 ... will keep testing! Thank you so much for helping me. smile

6 Reply by MC

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Re: [Solved] Issues with new Topping A70 Pro amp

With a High-Pass the gain is disabled (clearly visible on the graphic display as nothing changes).

Before you mentioned that 'Filter' is set to On. Are you sure you looked at the correct channel - Line Out?

Also you did not provide an example of the audio that you play. Would be interesting to analyze it.

Regards
Matthias Carstens
RME

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  • Registered: 2023-10-17
  • Posts: 17

Re: [Solved] Issues with new Topping A70 Pro amp

So, as an update... I disabled all the rumble filters and whatnot and reverted to using the RME and A70 amp as normal and the amp is basically not cutting out anymore (or at least it hasn't happened in like a week). It's almost like it "burned in" after a couple dozen hours and sorted itself out. I don't have an explanation, but it seems to be working! I'll follow up if the behavior resumes.

  • Registered: 2023-10-17
  • Posts: 17

Re: [Solved] Issues with new Topping A70 Pro amp

Hopefully final update - other users of the A70pro amp reported the same problem to Topping who issued a 2.02 firmware today to hopefully fix it. I think this was not a DAC issue at all, just something on the amp side. False alarm for RME! smile