PS-100 Day One Red Plate Tube using cab parallel out method

I utilized the method I found online in a youtube video utilizing parallel out from cab back into AMP IN on PS-100 to allow use of WARM and BRITE toggle switches. It worked until it didn’t. After about 15 minutes the sound sputtered and the left tube turned red hot before I turned the unit off.

I used the Mesa parallel box. SPKR OUT to Mesa box. Mesa box Out 1 to Marshall 4x12 Cab 4/8ohm input (set to Mono). Mesa box Out 2 into AMP IN. SPEAKER switch set to 4ohm, AMPLIFIER to 8 ohm.

Is this method okay to use? Was it improperly done and caused the failure? Is my unit damaged or do tubes need replacing?

Hi @UsernameU and welcome back to the forum

What’s your serial number, date of purchase and place of purchase?

I need a bit more clarity on exactly how things were connected when the failure occurred.

Hello Fryette Support:

I purchased my second PS-100 in November. the Sapphire Blue Chuck Levin’s Edition (local/near me as well in the DMV vicinity as we call it

  • PS-100 Purchase date: November 24, 2025
  • PS-100 Purchase location: Chuck Levins
  • PS-100 Serial number: PHID244071
  • Link to this forum post

Here is the link to the video that shows the technique I was trying to achieve.

https://youtu.be/8UAHpELWaCk?si=JSu3Z7_tcEXRtjCt


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Hi @UsernameU, I think you already edited it.

OK, this unit likely has fault tubes.

Please write to support@fryette.com

Subject: PS-100 replacement tubes and fuses

Include this information:

They should send you out replacement tubes and fuses. This might not be fast…

Take a look here for how to open the unit,

I purchased new tubes and fuses and replaced the faulty ones

Same configuration, everything is working as it should.

Happy to hear that worked. Did you write to support in the end? I think during Feb people were away, sick and too busy in general.

Yes I did. No problem and no rush on that. I think we had two email threads going on this, one email, one linked to forum. Easy to understand.