click on image to see full size. If you do, you will see the laminations in the right hand output transformer... each of those is actually three laminations. So three dark, three light, and so on.
And I'm back. The first thing I did wrong was hook two resistors to the wrong spot on each channel. Of all the resistors in the amplifier, there are only two that if omitted or misconnected can open
the portal.
The Portal is a passage to underworld, a world where physics are bent around the humor of the punisher... For example, this particular mistake can take a DC power supply in an amplifier that is only capable of putting out 350 volts under load and 450 volts with no load climb all the way up to 600~700 volts or more. I never had the nuts to see how high it would go before the entire amplifier exploded in my face, so I usually killed it at 600. Remember an amplifier is an oscillator designed not to oscillate ; ).
Other things the portal can make happen is a perfectly working amplifier to really mess with you or one that will not pass a signal at all or any combination of the two depending on the humor of the punishers. I said punishers this time (plural) because by now there are several standing around the crystal pool watching you.
In the case of this amp, it did neither. Instead it found something new and caused the cathode biased tubes to climb to hundreds of mills until smoke started coming off the cathode resistors and I had to pull the plug.
No worries, I found this one fairly quickly, having recognized that when something impossible is happening, the portal has been opened and the only way to open the portal is to leave out the grid bias resistors that follow the coupling-caps. Without that reference, turning on the amp immediately opens the portal. So I knew to look at those and sure enough I had them wired on the wrong side of the caps.
This is what happens when doing a new layout, because you are highly focused on the layout rather than the circuit and often make stupid mistakes.
My only thought after finding this, is that the amp probably will work now. It didn't. Still wouldn't pass a signal. This is about the time when you know it's time to buckle in and ride it out, or walk away.
The next day I gave it another shot and found that the reason it would only put out 500 milliwatts at full volume was because I forgot to wire the high voltage to cathode follower tube plates. HA, this is just like when I forget to plug an amplifier into the wall and wonder why the damn thing won't turn on... this is going to be easy.
My only thought after finding this, is that the amp probably will work now. It didn't. Still wouldn't pass a signal. This is about the time you have to balance the negative forces at play with some profanity. Without profanity man would still be trying to get the wheel to work. So I did that.
Sadly the amp didn't fix itself and jump to life so let it set for another day.
Today I fixed it.
Here's what happened... Even though this amp uses the exact front-end of a Zen Mystery Amp, I deliberately did not look at our working sample of the ZMA because I wanted to invent a completely different internal layout without being influenced by the original one on the ZMA. So instead I used my schematic of the ZMA to built the front-end and as a result did in fact come up with a better layout.
During that experience I became obsessed with the .1uf cap used in the tail of the long tail splitter (phase inverter). I became compelled for some reason to revisit it. Why did I make it .1uf? Can it be smaller? After diving down that worm hole I found out I made it .1uf because that is the only value that will work properly to balance out the low frequency response of the phase inverter. I was also obsessed about where to locate the cap in the layout. It really became all about the cap there at the end...
This obsession with the cap turned out to be a
misinterpretation of a warning from the Audio Gods who were trying to tell me there was a problem with that cap. The problem was that I drew the schematic wrong. Specifically when I drew the schematic, I drew on lead of this cap connected to the wrong place so when I followed the schematic I build the new amp wrong and wasted a lot of time comparing my work to the schematic in defiance unable to find anything wrong.
Once I looked at the ZMA, I could instantly see what happened.
So tonight it is on the bench doing some chin-ups as I write this. I will listen to it tomorrow.
I am pleased to report the biggest challenge being to get the 'TORII Harmonics' right, and at 1 watt they nearly perfectly match a Zen Triode amplifier, which is actually better than the TORII MK4, also, the distortion is lower. Depending on tubes used, the range is between 0.2% and 1% total THD. Of course if you stripped out that first harmonic which we all so dearly love, the figure would drop closer to 0.02%.
This will be a rich textured amp just as it has always been but with far more forgiving front-end with even lower distortion. The bandwidth also improves with the UFO transformers and overall resolution will be higher.
This weekend will be nice as I will start breaking it in tomorrow at work and by Friday night, we'll be ready to hear the results.
P.S.
I want you all to know that the hellish feeling of trying to fix something that you can't find anything wrong with happens many times to all of us as we put together your amplifies via this painful process. Circuit boards eliminate this. You can see why Decware amplifiers sound like Decware amplifiers. It takes real men to face this dragon on a regular basis and always come out victorious because there is no other choice. The longest the Audio Gods will punish you is 24 total hours. That's basically four work days. But they can be defeated in numbers, so if two or three of us look it over, the hours melt off quickly. That's how we overcome the dragons during the daytime, but this particular project like all new amps, I just fight alone so as not to burden my crew.
Steve
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