2. amps-preamps
  3. 189170-23267

This One has Me Stumped

I recently purchased a Pass XP-12 to replace my aging ML 38s. After installation, I noticed gobs of high frequency distortion, especially in Operatic female voices.

I measured every component in the signal chain separately. All are performing in spec.The XP-12 has very impressive test results.

Re-installing the 38s gets me immediately back to more mellow sound.

In my system, I have an EQ and crossover between the XP-12 and my Bryston 2.5b^3 power amp. I removed the EQ and the XO, plugging the XP-12 directly into the power amp. The distortion remains.

I am puzzled. I am a measurement guy. I use REW extensively. I can measure and troubleshoot almost any problem in my system. This one is a stumper.

Can anybody suggest a measurement or a way to solve this apparent component mismatch?

 

My system in order from source to output :

Shelter 901 MKIII MC or Koetsu RS MC cartridges

Parasound Zphono XRM phono preamp

Technics SL-1200G TT

Oppo BDP-105 Universal player (digital)

Bryston BDA-3 D/A ( feeds the Oppo signal to the XP-12 or 38s)

Sansui TU-X1 tuner

XP-12 (38s) line amp

dBx 1231 EQ

Rane AC22 2 way crossover

Bryston 2.5B^3 power amp

Usher 604 floorstanding speakers

HSU ULS-15 sub (when using the XO)

 

Thanks,

Kevin

 

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Showing 1 response by jji666

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jji666
445 posts
 

Similar experience when my source component was overloading my preamp.  I suggest you try every source and see if it's consistent or just a single source.

I suppose the preamp could also be overloading the EQ or your EQ settings are too high relative to the new preamp's signal and overloading the crossover.  Try turning the gain down on everything a bit, including if you have any variable gain on any source so you can be sure you're not overloading the pre. Basically turn it down young man! 

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