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Pass XP-17 + MM carts “clip/distort” on peaks, but low-output Paua II is fine — Overload?

 

Hi everyone — I’m trying to troubleshoot a phono issue and would love advice from folks who’ve run a Pass XP-17 with high-output moving magnet carts.

Setup

  • Turntable: Technics SL-1200GR2
  • Phono stage: Pass Labs XP-17
  • Integrated amp: Pass Labs INT-60
  • Speakers: Volti Razz

Cartridges tested

  • Ortofon 2M Black LVB 250 (MM, ~5 mV output)
  • Sumiko Olympia (MM, ~4 mV output )
  • Soundsmith Paua II (very low output, spec is around 0.4 mV)

Problem
With the Ortofon LVB and the Sumiko MM, I get what sounds like clipping/overload (severe distortion + occasional “popping” type artifacts) specifically on high energy / dense musical peaks. It’s not subtle.  On quiet/soft passages it sounds very good.  The Sumiko plays much better but still has the problem a few times on each track.

But with the Paua II, everything plays cleanly — no clipping/distortion on the same passages.

What I’ve tried

  • Verified this happens at the lowest gain setting I can select on the XP-17.
  • Tried RCA outputs from the XP-17 (still happens).
  • Same system, same records, same volume range.
  • Switched to Sutherland KC Vibe MkII phono preamp and everything works great with all three cartridges.

Why I think it’s overload (not mistracking)

  • Two different MM cartridges behave similarly (LVB + Sumiko).
  • The low-output Paua II behaves perfectly.
  • The distortion feels like “headroom running out,” not subtle sibilance or inner-groove distortion.
  • KC Vibe sounds perfect.

Questions

  1. Has anyone experienced XP-17 output overdriving the INT-60 line input stage with high-output MMs?
  2. Any known best practices for XP-17 + high-output MM into INT-60? (Pads/attenuators? Use RCA vs XLR? Any preferred gain strategy?)
  3. Is there a way to confirm whether this is clipping inside the XP-17 vs overloading the INT-60 input stage?

I’m happy to post XP-17 DIP settings (gain/loading/capacitance), cable lengths, and INT-60 input used if that helps. I’d really like to keep using the Ortofon LVB with the XP-17 if possible.

Thanks in advance — any troubleshooting ideas welcome.

 

brighamdoc
dover
2,504 posts
 

@brighamdoc 

In my mind there are 3 possible causes -

1. phono is faulty

2. phono is overloading

3. there are resonant peaks from the cartridge/arm/cable upsetting the phono

phono overload

most MM phonos run 40db - 50/56 is very high, particularly with your cartridges at 4-5mV.

I would suggest using the lowest setting 50db, which means you have to run single ended RCA's. On the INT60 for unbalanced you need to use inputs 3 or 4. If you use input 1 or 2 for a single ended input you have to use a shorting plug on the INT60. When you tried RCA's to get 50db did you set up the INT60 correctly ?

Resonant peaks generated by tonearm cable and cartridge

After setting the input to 50db, using unbalanced from phono to INT60, if you are still getting the problem - try increasing the capacitance loading, this will roll off the high frequency from MM's and will dampen ultra high frequency resonances that may be upsetting the phono.

Trying a different tonearm cable may work - bit hit or miss on this - testing changes to the capacitance load will tell you more.

If these steps do not work, your phono is either faulty, or unsuitable for MM cartridges with 4-5mV output.

 

brighamdoc OP
22 posts
 

Thanks for all the input, especially suggesting I contact Pass labs.

Kent English a technical support specialist from Pass Labs contacted me less than 12 hours after emaililng them.  That is pretty surprising since I picked this equiptment up gently used and he knew that.  He gave me some setup ideas as well.

I did try the 50 db gain through RCA using input 4 when I was trying things out.  It didn't help much if at all.  I have a new phono cable on order to see if resonance could be an issue.  I'm using a BlueJeans inexpensive cable and I'm going to try Nordost.  

I'm convinced none of the equiptment is faulty given the fact with different combinations I can get them all to work well.  Just not the combo I was hoping for.

I'll let you know when the new cable gets here and I try Kent's suggestions.

Hope all have a great New Year

Stan

audphile1's avatar
audphile1
8,106 posts
 

Kent’s great! I talked to him several times. 
 

As to cables, if you are not using phono cables from your tonearm/turntable to phono stage, it would not impact moving coil carts but would impact moving magnet due to wrong capacity. It shouldn’t result in clipping though. It would cause a frequency response roll off. 
 

I’m thinking the phono could be faulty. Pass will fix it for you. But it’s annoying nonetheless if it’s busted. 

brighamdoc OP
22 posts
 

I used a BlueJean phono cable and a Pro-Ject phono cable and didn't hear a difference.

audphile1's avatar
audphile1
8,106 posts
 

If these are phono cables then nordost will not fix the issue. 

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