Pass amp for newbie?

I've been wanting to build a system for quite a while and now I am about ready to take the plunge. My goals for this system are to build it myself and create something that is visually impressive and allows hours of fatigue-free listening.

Currently the speakers the amp will run (until I change my mind, again) are a line array with a Raven tweeter.

I had planned to power them with a SE 2A3 or 300B amp kit but after seeing some measurements (I didn't expect to be impressed) I was appalled and decided to rethink my decision. I was attracted to the tubes because they were different, looked neat, and fans of them are so fervent. But after seeing the Zen-lightenment article I decided to check out

From his site, I see many different options. I don't think need a lot of power so I am not too worried about heat dissipation. What design would people recommend that would put my Adcom GFA-545II to shame?

I should note that I've never built anything very complicated but I can solder well. Is a Pass design right for me?

The pass designs are simple but on some of them you must!!!! pay attention to the power requirements. This includes getting rid of the heat. The A75 article at pass labs has some info on heat dissipitation in it. Don't be fooled by specs, they can be misleading when it comes to our ears. As a matter of fact the specs on some of the pass stuff isn't all that great either, but electronic instruments don't listen to music we do. I have built a number of Pass designs and will be first in a very long line to praise them. That said, I'm going to build a SE tube amp very soon to see what the fuss is all about. After building the pass stuff, I don't pay attention to specs anymore. Good luck


2001-06-01 4:53 pm
The Pass project articles give detailed information on power requirements. The SOZ is the worst because it is so simple and uses a resistor for a current source, but all Class A designs throw out a lot of heat.
What kind of output power are you looking for? We can start from there.
I second Skippy's advice about not getting hung up on specs. It cost me untold thousands of dollars to learn that one, simple lesson.
That said, be realistic in your assessment of how much power you'll need. If you think you can get away with five or ten watts, and build an amp of that general power rating, you could come away with a bad taste in your mouth, blaming the amp (whether tube or solid state) for sound problems that were actually caused by pushing it beyond its capabilities...

I agree with the advice on specs. I knew they would not be in line with those of mass market solid state amps. I just didn't realize how different they could be. I'm over that now.

Power requirements? Well I plan to drive a fairly efficient line array (Axon Array 3R or Orca Array). I plan to keep using a Velodyne F1000. Wouldn't 20-50W be more than enough?

I don't know when I will tackle the speakers so it would be nice if it could drive my Snell K/IIs (90dB?) at moderate listening levels.
Most SE tube amps of 6 watts or lower would have a problem driving the snells. They work well with higher SPLs. I listened to a pair of snells one time and fell in love. They cost too much though. 20 to 50 watts would drive the snells alright though a larger Son of Zen would be a risky venture due to the power supply req.

Mass market electronics always spec out good due to a number of things. The biggest one I can think of is deception. They don't always lie mind you. They just don't have standardized tests. Some of my favorites are "Total Music Power" and any spec measured at a single freq ( typically a burst test at 1khz). The problem is most consumers don't really understand what their reading to begin with. Years ago they used to all out lie about wattage. Even today most wattage specs are peak and not continuous. Good luck.

P.S. someone in the trading post section has a parts package for sale for the Son of Zen that incl. all of the hard to find items. If you decide to go that route.