“A low-wattge, single-ended amp without the drawbacks of a low-wattage, single-ended amp!” – Dr. Z

Having a love of small, single-ended class A amps since hearing the opening bends of Joe Walsh and the James Gang’s staple “Funk 49,” a huge tone that was recorded with the tiny 5-watt tweed Champ, Dr. Z followed his ears in his latest offering, the PHD. The attraction to class A, single power tube, single-ended amps is in their hallmark of swirling, even order harmonics and the additive play-feel you get from pushing a power tube towards its limits, especially without blowing the roof off with volume. Yet, the Champ’s small 5w output has its limitations, with minimal headroom and a looser, narrower bandwidth as the volume increases. Dr. Z aimed to retain the charm of the Champ’s raunchy overdriven sounds but increase the sonic potential with better headroom, clarity, and control.

Looking to other amps in the same single-ended camp, Dr. Z noted that Telecaster master Steve Cropper’s crisp, accurate clean tones were played through the rare tweed Harvard. Looking for that broad bandwidth coupled with punchy headroom, Z replaced the common 12ax7 preamp with the robust octal-based 6SL7 tube for a richer, muscular sound signature. Selecting a Gold Lion KT 66 power tube to replace the smaller bottle 6V6 added depth, articulation, and the frequency bandwidth he was looking for. Finally, substituting the low voltage 5Y3 rectifier with the more powerful 5U4 gave the PHD more wattage, cooking it up to a useful 10 watts and sitting in the sweet spot of enough clean headroom to reproduce pedals through the front end but still give the player the churning grind and responsive feel under the fingers that a class A KT66 pushed into overdrive generates.

The PHD is equipped with a single tone control, a note taken from the classic Harvard design, and adds a master volume to achieve great overdriven tones at lower volumes or maximize clean headroom. The PHD 1×10 combo is build around a WGS G10 C/S speaker in a lightweight and highly resonant poplar ply cabinet, weighing in at 29lbs, making a portable amp with a big sound, without the boxiness typically heard from compact combos. Also available as a head, marry the PHD up to a 2×12 or even a 4×12 for a very lightweight head that will surprise you in its sonic footprint, opening up two big bottle octal tubes and pushing them to the brink without clearing out the front row.

Specifications:

• Power Output:    10 Watts
  
• Output Tube:    1 – KT66, Cathode Biased
  
• Preamp Tube:    1 – 6SL7 (octal preamp)
  
• Rectifier:    1 – 5U4GB
  
• Controls:    Volume, Master, Tone
  
• Configuration:    1×10 Combo with WGS G10 C/S
  
• Dimensions:    17 1/2” W, 17” H, 10” D
• Weight:     29 lbs
  
• Other:    4, 8, & 16 ohm outputs