[Ken B]

I have recently acquired a 006t amp and have noticed that the IEC connecter (hot and neutral) is wired in reverse. I can determine this by using the Stax supplied two prong non polarized power cord and taking voltage readings with each plug orientation. The voltage on the chassis will be lower when the correct orientation is used. When the AC polarity is correct the sound is greatly improved. The bass is lower and tighter, upper frequencies are smoother along with a quieter background. So when using other 3 prong power cords the polarity will be incorrect and not benefiting fully of what this amp is capable of. Of coarse this is easily correctable internally, but I am curious if this issue applies only to amps that are purchased directly from Japan as this one is, as compared to ones designed for the North American market.

Anyway, I just wanted to make other owners of Stax amps aware of this issue if it actually is indeed an issue for others.

Regards,

Ken

 

[kevin gilmore]

I recently repaired a srm-313 for a friend. Both inputs wired together
so the unit not only made mono out of the headphones, but shorted
out the preamp too. Stax quality recently, very poor.

 

[sherkaner]

After lurking for years here, I just made an account to post a reply on this thread.  I just wanted to say thank you for mentioning that you noticed this difference in sound with AC polarity because I ran into exactly the same thing.
 
I have an old Stax Classic System (SRM-313 and SR-303) and recently had been really disappointed with the sound quality. I assumed a cap had gone bad or something else and I sent the system in to Yamas/Accutech for repair.  No fault was found with the system though (they were very nice and didn't even charge me the diagnostic fee).  When I got the system back I was grumbling about what was going on and started wondering if there might be something AC-related -- a search brought me to this thread. I tried plugging in my Stax with the 2-prong AC plug in both orientations and there was a very clear difference in sound in one orientation vs. the other.  One way the Stax sounded beautiful and the other they had the muddied treble and mildly distorted bass that made me send the system in for repair! I remembered that around the time I noticed the drop in sound quality, I had switched the location of my Stax and so I must have gotten "unlucky" with the orientation of the plug in the new location.
 
It's really odd that this isn't mentioned in the user manual at all. Maybe it doesn't cause a problem with all AC power or something, but it certainly did at my house at minimum.  Worth trying flipping that plug to anybody who has Stax out there.

 

[krl25sc]

Thanks for pointing this out, will examine my 353 later and see if it has this issue.