ENGL Thunder E325 tube question

I have an ENGL Thunder head E325, I was wondering about the 12AX7's in this...

I bought this, I had played through a friends Thunder combo I was so impressed i got the head used. I instantly opened it up after a trial sound check and found that it had the original tubes in it....all ENGL branded. Holy crap! no wonder it sounded so dead and fluctuating loudness. I ordered some Ruby Cryo Power tubes matched of course, I always put these in my Marshalls, their reliable and sound good to me.

So I'm having a problem getting good info from ENGL. After repeated emails about tube positions and recommendations, I have come here for real professional help.

What are the pre amp positions and any recommendations for tubes. My idea was V1- Ruby 12AX7 HG, V2- Tung-Sol, V3- Tung-Sol, V4 Sovtek 12AX7LPS... I'm assuming the phase inverter is V4...which is my main question.

I'd guess V1 input and V4 the phase inverter, based on the online descriptions. In my experience "tube rolling" each individual tube will likely have some audible change when compared against others. My method of optimizing preamp tubes is to A/B them one at a time and pick the best one before moving to the next position. For instance: compare V1 existing tube (X) against another (Y) and let the best sounding (X or Y) remain. Now, try again with another preamp tube (Z). Keep trying that in V1 position until you have (to your ears) the best tube in V1. Now move on to V2, etc.

Be aware of utility tubes such as reverb drivers. Phase inverter may or may not fall into that category, depending on the circuit. If your amp has a post phase inverter master, then I'd go to that spot immediately after choosing the best for V1.

thejaf said:

I'd guess V1 input and V4 the phase inverter, based on the online descriptions. In my experience "tube rolling" each individual tube will likely have some audible change when compared against others. My method of optimizing preamp tubes is to A/B them one at a time and pick the best one before moving to the next position. For instance: compare V1 existing tube (X) against another (Y) and let the best sounding (X or Y) remain. Now, try again with another preamp tube (Z). Keep trying that in V1 position until you have (to your ears) the best tube in V1. Now move on to V2, etc.

Be aware of utility tubes such as reverb drivers. Phase inverter may or may not fall into that category, depending on the circuit. If your amp has a post phase inverter master, then I'd go to that spot immediately after choosing the best for V1.

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Thanks You were the only help I got from all the forums I belong to, and one was Rig-Talk...they had no clue whatsoever, ya know the best answer i got from them? "try google" ! lol I've never been able to depend on those idiots...imagine a forum dedicated to guitar rigs and having no clue where the phase converter would be on my amp...or any amp.

You guys were correct, although I assumed the phase inverter was the lat one, I had read it's not always, and by the way ENGL finally got back to me and confirmed what I thought and what you knew.
I also did checking tubes vs each other. I found that Sovtek LPS in the V4 really gave my amp warmth. So to reiterate Ruby Cryo power tubes, V1 Ruby 12AX7ACS HG+, V2-V3 Tung Sol 12AX7, V4 Sovtek 12AX7LPS. Sounds great!
Thanks again! :yah

I think this problem is down to the fact that the 5881/WGC

Glad it worked out! :hank