Steve Deckert
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We'll you should know I couldn't just let it lie there... right?
I put a quad of Genalex KT77's in the TORII MK5 to see what would happen for the guy who wants to spend a bit more than an EL34, and dammit now to be 100% sure the ZMA is actually better I have to compare one more time...
The piano notes are harder and more lifelike with these tubes and the bass is more refined, flatter. Really nice sounding tubes in this amp which is no surprise.
Honest to God I couldn't tell you which amp will win with it's own favorite tube compliments in the end once they are both anniversary modded. The fact that this amp is cathode biased and has better output transformers means it is not impossible to beat the ZMA, but the ZMA power supply is so over the top that even against all that it may well still win.
Ahh, amp wars. Brings back memories. It's how Decware was started. No, actually it was the process that built the confidence to start Decware.
Pitting one amp against the other and pulling out all the stops for each trying to be the best sounding. It's how the Zen amp was developed. Four years of taking two Zen amps and modifying each in a never ending battle against each other. That is btw the secret. Build an amp. Like it. See if you can build another just like it, that sounds just like it. See if you can do it a 3rd time. This proves the layout. Then take one and put it in service in the garage and take the other two and listen to them to be certain they are identical.
Once this has been confirmed after months of burn-in, you take one and start to mess with it in an attempt to make it sound better than the other one. If you succeed and it stays that way for a month or two, then it becomes the new champion. You now take the looser, and see if you can refine it in such a way as to beat the present champion. It's a lot of fun and immensely enlightening. Like I said, this went on for almost four years before the first one was actually sold and then as we got past the first 25 amps, customer feedback refined it to another revision and another and another and another and another.
Any time you are the creator of two amps and are listening to them one against the other in the center of your universe with all your tools and toys and parts inventory only seconds away from the listening chair... wonderful things can happen. And interestingly in this entire process a computer or calculator is never used or needed because it is always faster to just solder-in and listen to 8 different value resistors than it is to model their effect on the circuit. Trust your ears. My guess is most spice models go through several revisions, at least 2 or more. In that four years I went through 111 different variations of the same amp via amp wars model. All the while I had the original in the garage to bring back in for reference to see where I have taken things.
People think it's about parts, or about circuit superiority, or power, or whatever, but in reality it's about how many different revisions did you actually build and listen to in a treated listening room on no less than 10 pair of reference speakers. If you build an amp with only one pair of speakers you will be sadly disappointed when you take it to your friends house and it sounds like crap... So as I listen tonight to the non-anniversary modded TORII MK5 with different output tubes against the ZMA is the MK5 has more presence and is a bolder sound. The ZMA is more polished and refined. I don't think Anniversary Mods are going to reverse this behavior. If anything it should push it harder in the other direction. That could well make the UFO transformers suddenly take things to a more lucid level making this amp sound more real.
I have to say the Russian interpretation of the British sound in this KT77 is really good. More weight and depth, but still that wonderfully flat and honest take on things. Very nice.
I can see this is going to become an ideal tube rolling amp. I sounds great on KT88's too and now curiosity is going to kill the cat...
I think KT77's will be the upgrade tube for this amp in the shopping cart if we can keep them in stock.
This is a good example of one of the advantages of a cathode bias amps... one of the many advantages so long as you can live with lower power. A ZMA can't use the KT77 because it bias too cold for the window I set in that amp. Fixed bias amps have windows that limit the tube choices to protect the user from melting tube plates by setting the bias too high. A Cathode bias amp is self regulating so the KT77 in the TORII MK5 bias up to 50 mills where it is happy. In the ZMA it only would adjust up to 30 mills.
And of course on 100dB speakers like the ZF15L Zen Master Series Baffles I am listening to tonight, there is zero difference in perceived power between the two amplifiers at any volume I could possibly stand to listen to.
Steve
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