Part 3
 
So anyways... The challenge was make the darn amp - while keeping it affordable. Obviously that huge linear power supply (two power supplies actually) sitting on top of the Teac DAC serving as place mat would put the price way past $1k territory. I believe another consideration was compatibility with 220V since it seems the American market is reaching a saturation point. Evidently a lot of EC orders are now from Asia.
 
Board #2 - pre-production: The PCB is now expanded to include a high-frequency charge pump, DC to DC. A cheap 12VDC wall wart compatible with 115/220 can now be used. Extra power supply capacitance has been added. You can turn off the amp, and it will run for a few seconds. Also, the input transistor pairs are changed out and replaced with a single package with matched parts.
 
I take this to work. Hmmm. Bummer. Kinda bright. Not totally nasty bright, but bright. Thin. Bass has good extension, but impact is lost. I say to Craig: "Fuck it, not worth making. It's decent, but it doesn't distinguish itself. I mean it's good, but there's so much other there, and everyone else has a better marketing strategy than you. And they also pay Jude. This won’t sell.”

“Is this the fault of the power supply? If the linear power supply is the secret, then there's no way for you to make this amp affordable."
 

Really fascinating...mirrors our experience with switching supplies. And charge pumps? Yark. Really interested to hear if he got it working. If so, kudos.

You can borrow this. I can drive to a meet, and take it out of the car. It's tiny and only a few pounds.

Will there be a 230V option? Does it handle more sensitive headphones such as the TH900?

Part 5 of 5

So to end this story quickly. EC found a source for the transistors. With the power brick, charge pump circuit, and Toshiba transistors, the pre-production amp now sounds about 80% of the original prototype. The original prototype with the linear power supply had a bit more slam, sounded a bit more organic, dug in with little bit more authority. The differences are were significant. Even less or possibly non-existent if you are using a modest DAC.

Now don't quote me on this, but there is a possibility that Craig will make an external tube power supply for the amp at later time, with an appropriate connector which bypasses the internal charge pump. That would be pretty cool. But it is not confirmed yet. Hopefully at least we can get a connector for an external PS starting from the first production units.

The Red Top is still very much a solid-state sounding amp, but with some of that Eddie Current organic quality and not harsh in the treble. Being a solid-state amp, it does do certain things better than the EC tube amps, namely precision, delineation, focus, and blackness. However, don't expect BA or 4-45 microdynamics, microdetail, or staging. In fact, I think the Krell Klones and prototype Rags I've heard were more resolving. The Mjolnir may even be a teeny bit more resolving. But for those who enjoy the EC house sound or want to get a taste of it in any easier to handle package, the Red Top may just fit the bill.

I'll leave the last line to quote Craig: "Are there better amps? Fuck yeah. Are there worse amps? There are plenty of them. Pick an amp that goes well with your headphones and be done with it."

+ treble is not harsh or etched
+ organic quality with almost a tube-like bloom, not dry sounding
+ hits fairly hard with DACs of sufficient capability
+ precise, focused, delineated
+ good stage for SS amp; open sounding, good center image
+ extremely flexible in terms of AC input voltages
+ works with a lot of different kinds of headphones
-  not as resolving as the best amps
-  not able to reproduce quick small volume changes as the best amps
o still better than most of the stuff out there considering price