MY GOALS FOR THIS AMPLIFIER
This amplifier has been designed using a Sadowsky SS-15 hollow body guitar for tuning and playing. I desired to have the best clean tone possible and is the primary goal for this amp. Here are some of my other requirements:
1. A class A single ended guitar tube amplifier with an output of around 10 watts, and one that provides a very rich tone with nice harmonic content.
2.The amp is to be hand wired using 4 turret boards. Layout and grounding must be the best and requires experimentation as well as prior experience to accomplish.
3. My pre-amplifier tube of choice is the EF86. The 12AX7 and cathode follower circuit is to add back the gain that using a tone stack removes. In this way, this amp isn’t compromised when using the tone stack (treble, mid, and bass).
4. In order to provide tonal options, I test all power tubes that can be usedto determine which sounds the best for this amp (KT88, 6550, EL34, 6V6, etc). Hence, the power voltage needs to be kept under 400 VDC. By doing so, you can run almost any popular output tube and also only need 1 and not a matched pair or quad’ using this design.. The 6V6 requires a lower cathode resistor value, but the other power tubes all use the same higher value and are easy to compare.
5. I need a full EQ tone stack (bass, mid and treble) to sculpt my tone. Using a cathode follower circuit to drive the tone stack eliminates a big reduction in gain (by adding the tone stack) and doesn’t degrade the tone.
6. My ultimate goal is for this amplifier to also be very quiet and I’ve accomplished that.
It’s difficult to design an amp to do both clean and overdrive well and that’s why many amps that attempt it have one channel that’s “not so great.”
I’ve designed this amp to have the best quality clean tone and highest amount of headroom for the power tube used. This amp has also been “tuned” for the Psvance EL34PH new production power tube. This tube has a nice linear presentation and the shimmer added is beautiful. Bass is huge (when played through a 12” speaker) but again, not overpowering. This of course can easily be adjusted using the bass pot installed in the amp. When the tone stack pots are adjusted well for your guitar and speaker, the entire frequency range sounds beautiful. There is no ice pick sound quality nor does it sound thin in any way. Sound quality is optimized and beautiful. This is exactly what a hollow body guitar is designed for – this kind of tube amp – and is why I’ve created it.