Carr Amplifiers Hammerhead Mk II FAQ
Answers to frequently asked questions about the Hammerhead Mk II.
- How is the Hammerhead Mk II different from the original Hammerhead?
- What tubes are used in the Hammerhead Mk II?
- When and why was the Hammerhead Mk II discontinued?
The General FAQ on the Support page addresses additional questions about tubes, speakers, purchasing a Carr amp, and more.
How is the Hammerhead Mk II different from the original Hammerhead?
The main difference is that the Hammerhead Mk II has a relatively traditional Tone control in addition to the Impact and Grip tone shaping controls. The Mk II also has a little more power supply filtering to make it a little tighter in the bass frequencies.
What tubes are used in the Hammerhead Mk II?
We refer to the tubes and their positions in the amp as V1, V2, etc. for preamp tubes and P1, P2, etc. for power tubes. The number indicates the position of the tube as counted from right to left when looking at the back of the amplifier. The right to left progression follows the circuit from input to output.
| P2 | P1 | V2 | V1 | |
|---|---|---|---|---|
| Type | E34L | E34L | 12AX7 | 12AX7 |
| Manufacturer | JJ | JJ | Electro-Harmonix | Electro-Harmonix |
| Function | 1/2 Push-pull power stage | 1/2 Push-pull power stage | Phase inverter | 1/2 Initial gain stage, 1/2 in parallel with phase inverter |
The Hammerhead Mk II is a cathode bias (self bias) amp and as such does not require a bias adjustment when changing tubes. Please use well-matched pairs of power tubes for maximum performance. The Hammerhead Mk II can only use matched pairs of EL34, KT77, KT88, or 6550 power tubes. (The JJ E34L is their premium EL34-type tube.)
Carr Amplifiers selects and tests the finest current production tubes specifically for each amplifier model. Caution should be used when buying replacement tubes from any dealer who does not have a return policy as all tubes can have problems (NOS tubes are susceptible to microphonics and failure too).
When and why was the Hammerhead Mk II discontinued?
The Hammerhead Mk II was officially discontinued on 01 Jan 2010. Though it is a versatile and great sounding amp, it was not a big seller. When our stock of Hammerhead transformers and chassis began to run out at the end of last year, we couldn't justify the expense of ordering a new run of parts.