This morning as I sat down in my office to check email and the like, I looked over at the amp in the corner of the room and made a snap decision. It was time to perform a SET swap.

For a while now, I’ve had the 6CY7 V2 Zebrawood playing music in my office as I work at the computer or at my work desk. I really enjoy this amplifier. It has a rich, full, and warm sound that really brings music to life. And in my 12ft x 11ft (3.6m x 3.4m) office it produces plenty of power for listening at any volume that strikes me.

However, sitting on the self right next to it was the 6EM7 Vertical Amp. I haven’t played the vertical amp in a while and I decided it was time for a change. So I took it off the shelf ( removed the embarrassing layer of dust) and swapped connections. When I powered it up an immediate smile came across my face. It opened up with a some moderately fast instrumental jazz and it sounded incredible!

Both of these SETs have excellent sound. However, at equal power levels, the Vertical Amp has about half the harmonic color of the Zebrawood amp. And this affects how it sounds with certain pieces of music. Not that one amp sounds better than the other, they just sound different. Sometimes it’s easy to forget that different amps have different sounds and that those sounds can be really enjoyable.

Technically the 6EM7 Vertical Amp has about 5dB more input sensitivity than the 6CY7 Zebrawood Amp and about 3dB more headroom. The bandpasses of the amps are, for all practical purposes, identical. At the 20Hz the 6CY7 is down about 1.7dB and the 6EM7 is down about 2.8dB. The ≈1dB difference is imperceptible. At 20kHz the 6CY7 is down about 0.6dB and the 6EM7 is down about 0.7dB. This is virtually identical rolloff and is probably due to the same output transformers used in both (Edcor GXSE10-5K).

But it’s really that 2nd harmonic response that makes all the difference. Don’t get me wrong. I really enjoy the Lacewood V2 which is currently my main A/V amp connected to the big screen television. And the Marblewood Amp (with a nice pair of 6L6s in the power stage) which also sounds excellent is a network connected amp in my family room which allows anyone in the family to simply stream music over the wi-fi network. These amplifiers are both solid performers which sound really good. But there is just something about the sound of these little SET amplifiers which is truly addictive.

So the 6EM7 Vertical Amp is back in play. I’m going to spend some time enjoying the 6EM7 while I work on new designs. I think the take away here is that just because you have an amp and it sounds really good, that is no reason to not try something different every so often.

As always, questions and comments are welcome.