UPDATE - June 2015 - See the
6EM7 Single-Ended Triode (SET) Vertical Amplifier project page for more details.
So, I've been working on a couple of different small amps (as I mentioned
here) and I finished one of them today. And this amp is just a little bit different from what one normally sees. Let me explain.
I decided a while back that I needed to take a different tack with respect to my amp chassis. Things just seemed to be getting a little too predictable. After discussing the matter with my son (he studies human design as one of his hobbies), we decided that it would be interesting to change the default form factor from planer to vertical. So I laid out a plan for a big 807 triode strapped amp in the new form factor. However, before tackling the main project I decided to prototype the idea in a smaller package. This would allow me to study the issues associated with this type of build so that I have a better idea of how to attack to big amp. So this amp, is really all about the chassis design. Well,
mostly about the chassis design.
For the electrical design, I settled on the V2 version of the
6EM7 amp that I designed for Mark way back in October 2011 and modified in December 2013. And while building it, I even ended up modified the power supply design somewhat. First let me show you how it looks.
Attachment:
Finished Front.jpg
Attachment:
Finished Right.jpg
Attachment:
Finished Left.jpg
The chassis is all black walnut with several coats of Birchwood Casey "True Oil" finish. It then has a couple coats of a quality furniture wax applied to give it a slightly aged look. The handle is a reinforced leather amp handle for easy portability. The amp weighs in at 22.8 pounds (minus the power cord).
In this design the tubes fit in little cubby holes made of the same walnut as the chassis for the sides and back and aluminum plate (painted black) on the top and bottom. Each cubby has vent holes in the top. The back plate has vent holes at the top so that the natural convection airflow is in through the front, up inside the amp, and out the back vents at the top. The amp also sports dual current meters to monitor the power stage cathode current in each tube. Power switch and indicator light (with amp jewel) are on the front along with the master volume control. The lower tube is a 6CA4 rectifier for the power supply. Various electrical connections are on the sides. Overall the amp is 17-1/2" tall (not counting the feet), 12" wide at the widest point, and 7-1/4" deep. This compact size will allow this amp to sit on the back of a desk, or on a book shelf, without taking up an undue amount of space (only 7-14"x12").
The amp sounds great. It is dead quiet at full volume with a paused iPod attached. It has a special split filter power supply for each channel that gives it an unbelievably deep and wide sound stage. Every instrument and vocal shows up in it own position while listening. Here is a picture of the amp playing it's first music.
Attachment:
Finished First Music.jpg
I consider this amp to be a great success. It sounds wonderful, it looks good, and I have learned a whole set of lessons for attacking this type of design. Now when I attack the big 807 Triode Strapped amp, I'll know exactly how to proceed for best results.
So what do people think of the approach? Let me know.
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