Paul Anwiler's Epiphone Valve Jr. and
Mercury Upgrade Comparison Clinic

[Ed. Note: Paul and his friends took it on themselves to conduct their own A-B testing of a stock Valve Jr. vs. a Mercury Mod version. This type of response is not uncommon, we receive enthusiastic responses like this all the time.]

Dear Mercury,

Attached are a few photos from the clinic we had on March 3rd comparing an Epiphone Valve Jr. with the Mercury Upgrade to a stock amp. For all comparisons we used a stock Fender Twin cabinet with 2-12 inch speakers running at 4 ohms.

A number of instruments were used in the comparison: an Indonesian Strat, a pretty good Chinese Strat, a real Strat, a real Tele, a Custom Shop Les Paul, an old Les Paul recording model, a nice Yamaha solid body and a harp player using an Astatic Bullet mic.

Additionally, we tried a number of tubes swaps in both amps. Not surprisingly, a GT EL84-S produced dramatic results over the stock Sovtek output tube. I liked #4s but some preferred #6s. Various preamp tube swaps were effective, as well.

The benefits of the Mercury Upgrade were obvious to everyone: better tone, increased volume, smoother and more pleasant sounding distortion plus greatly increased sustain. Another interesting observation was that the stock amp would only feedback steadily on three notes whereas the modified amp would feedback reliably over a nearly two octave range. In short, the amp had a much more linear response using The Mercury transformers.

This photo shows the setup with the Strat copy.


This photo is of Rick German a local musician who plays both guitar and harp and has quite a collection of amps. Rick owns the stock amp used in the clinic.


This photo reveals a couple of serious musicians: Eric Schatte, a hard core touring pro on the left with the Telecaster and Terry Selfe, a local player and happy owner of the modified amp.


Thanks also to Jason Schwanger for his input on the preamp tubes, Rick Szempias for adding his perspective as a harp player and Mike Dearth, a seasoned local pro, for pointing-out the change in feedback characteristics.

A lot of good ideas were exchanged including a number of suggestions for additional mods and speaker combinations. We all looked forward to having another clinic, perhaps late spring or early summer.

Thank you for your help with this project. I look forward to working with you again. 


Paul Anwiler

Paul Anwiler Technical Service

Authorized Mercury SSN

Toledo, OH

(419) 349-2207


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(818) 998-7791

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