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In Reply to: RE: Thanks. Is that all: "a unity gain 1:1 transformer"? I ask because posted by Frihed89 on February 18, 2009 at 23:38:08
one : measure AC voltage out from your DAC chip, say at 100Hz, 500Hz, 2kHz and 10kHz(from a test CDs. stereophile, chesky, etc...) (use an o-scope. most DMMs are frequency selective). two, measure AC voltage at the grid of your first triode (again use o-scope). three, measure AC voltage out of the unit, at the RCA output. Let us start from there ... BTW, what is/are your tube/s and how is/are they configured? Let's get the voltages and then we ask the guys at tube diy. For all we know, you already have the best there could ever be ... A transformer could provide magical mids, but soft lows and highs. You'd probably need, assuming you need a pair at all, a very small transformer. Get one encased in what is known as mu-metal shield (metal cylinders) like the ones used in microphones or just a little bit bigger. But transformer specs has to conform to your specific circuit. Another btw, a bigger "improvement" could be achieved by building a better and separate power supply for both the digital board and the output tube/s. Cheers
Thanks very much for the detailed information. I see where you are going. I don't have access to an O-scope, but i do have access to a local technician who upgrades AN equipment.
The DAC and output circuits (and parts) look identical to the AN Dac 1.1x/II Sig. I say this not as result of measuring anything, but poking around under the hood. Th tube output is 2xECC88s. It looks like a cathode follower. Is that possible?
I think you are right about new power supplies, but this looked like the easiest, cheapest first thing to do, but it may not be as easy as it looks. Maybe I was wrong. I have decided to stay away from the jitter issue. It's too complicated for me.
"Live free or die"
i started reading on digital-jitter, etc...I am afraid that by the time I would have a vague understanding, I wouldn't be able to handle a soldering iron anymore ...the great digital divide... hehehe. k-follower is possible, low Zout for dynamics. But you'd get "gain" of around 0.9. That means a voltage amp BEFORE the k-follower. I did see some AN stand-alone DACs and they used what they called an SRPP configuration, producing around 2V peak-to-peak output. Sitting down with a qualified tech would be the way to go. Enjoy the weekend.
I've been talking with a local guy and Lukasz Ficus, a polish guy who is called "The Lampizator". He has a home page that's fun under the last "name". He comes highly recommended by the chief designer at deHavilland whose name I will not drop, but i respect her openness and products a lot.
"Live free or die"
ya ... Lucas not only knows a lot, but more importantly, has had long experience with many digital circuits
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