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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
audioquest4life
788 posts
 

I would experiment with a bold loading setting such as 47k to see if the issue diminishes or goes away. Also, adjust the phono amp settings as much as possible such as lowering the gain to about 35db. A .4mv output MC cartridge requires higher gain, more close to 55-65db range. Actually, adjusting the gain down would be my first step towards trying to reduce the amount of output and lower the overloading you are hearing. 

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
8,102 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.

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