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| Romy the Cat's
personal site dedicated to advanced audio and evolved music reproduction
techniques
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I agree, I like the idea of glue or resin to attach components to a chassis. It adds a nice layer of damping material. I used to to this with step-up trannys for mounting in a box. Works great with the Cinemag or similar style cans.jh...
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My first answer would be "3". But then I think some more...Is "A" really a shunt? Where is the power dissipated? Certainly not in the capacitor. The signal is burned off (converted to heat) in the series element! In circ...
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I'm not convinced a constant side load on bearing is good. It causes assymetrical wear. Just seems to me a center balanced bearing with no lateral loads would be better. Merely an intuitive hunch.
As for the copper, yes, it...
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Wow, I never thought of that before. But you could be right. Perhaps the only section of belt contact that matters is that last inch or two before it leaves platter. Clearly the belt does not push, it can only pull. And if bel...
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I was not there! But I like the idea of the halved horn. Does that work? Seems to me it creates a huge wavefront discontinuity. Clever in terms of usability, anyway. Also, the pillows. They have to be messing with ...
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Sounds like a Tesla turbine.
jh...
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Paul, I think that is a very good observation. Seems to me that a really thick grease or oil in a large bearing would offer enough friction such that the motor was always biased into an active positive torque region. Such would be the equ...
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[quote]I wonder what would be the 7721’s plate impedance at 12mA[/quote]According to the chart on the last page of data sheet, I'd say roughly 2.4k (as a triode). You can always add resistance in parallel with the load.jh...
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I believe a lot of the issues with earlier DD tables was that they were all servo controlled. That is, a feedback loop kept the average velocity constant. As a musical passage of complexity would slow the platter, the loop would respond w...
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So why wouldn't you just copy what was done with most cutting lathes? Seems to me that stylus drag would be roughly the same (geometrically) for both cutting and playback. Thus, the cutting lathe slows down in response to large orch...
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[quote]Will the final appearance be similar to the prototype in the picture?[/quote]Yes, I can't imagine it changing much. Parts may change, but the layout is fixed. Size of box is 10x10x4 in inches. Weight, I think is only 15 pound...
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[quote]very short tube, shorter then it should be[/quote]Hmmm, I'll have to double check. This is actually one of the tubes you sent me. It is a little taller than a 6H30. I bought a bunch more off of eBay but haven't fired them up ...
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[quote]I feel that listening evaluation are the only objective measurement that we have[/quote]You are lucky to be able to bask in such luxury! It is one thing to build an amp for yourself, constantly tweaking and upgrading. Quite another...
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Ok, I did it a little different this time. At full power levels, the dB meter still showed wideband response. However, looking at the scope I could see distortion in the waveform. So instead, I lowered the input level to -3dB from f...
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But here it is. I made this monoblock fit into less than a square foot. It is tight. I use Hammond iron throughout. Their stuff usually works pretty good for power supplies. I have some photos at my blog. [img]http...
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I chose the 170V point as midway between the 250V supply I had for the CCS plate load. The choice was for maximal signal swing in both directions. [quote]in a properly designed amplifier a transformer should clip before the active stages[...
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[quote]Do you plan to develop this amp to a commercial product?[/quote]Yes, this is slated for production. But I really doubt I will sell many. Perhaps a few pairs. It's a bit out of the mainstream. Really need to us...
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I run the driver tube at 170V @20mA. I don't think you need to run this tube at high current. It is very linear with wide signal swings at this bias. I can get roughly 70Vrms out of it. Output stage clips first, driver continu...
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Oh, I forgot, the input sensitivity is roughly 0.95Vrms. At 6W power, the output sinewave looks like this:[img]http://www.hagtech.com/blog/images/pa-10power.jpg[/img]When driven into overload, a +6dB input (1.9Vrms) generates 13W output and it ...
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I got my second version of new power amp up and running, this time using the 6E5P Romy recommended. Output tubes are 2A3. Amazingly, this amp runs at 0.12% distortion at 1W. No feedback anywhere. It is simple two stage amp run...
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The answer will be a complicated one, as the preamp is driving an active crossover. The many storage elements means the impedance is a function of frequency. There is no "10k ohms" answer. I hope you are driving these network with s...
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That 8233 might do it. Also noticed the 6CL6 in triode mode will get you almost there, but only a mu of 20. The 6688 could be a substitute.jh...
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Romy, you were right. I just got in another pair of 7788 from eBay. This time, one tube has a little bit of microphony, not bad, really. The other was dead quiet! No ping at all. Very impressive, that sample. So no...
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I bet if you take that RTX off it don't sound as good.
jh...
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Wait a minute ... will a choke input work with a gas tube as a load? The choke-rectified input is designed to work into a resistive type load, but basically acting itself as a voltage source, capable of psuedo regulation over a wide range of lo...
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Maybe I was a little hard on these tubes. I have this habit of listening to noise floor at extra high gains. Maybe 20dB above loud. It is part of the design process for me. I like to hear all of the hiss, whine, buzz, hum,&nbs...
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[quote]a sufficiently-large last capacitor with using in input choke make the sound or transformer, rectifier and choke less relevant[/quote]I have to agree with Dima. The power supply has to be harmonious with the amplifier yet separate at the...
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[quote]biggest problem was the effing electricity?[/quote]I was thinking the same. Maybe due to the snowfall? Or the reaction of all the other folks in your neighborhood to the snowfall? Behaviour patterns and power usage are out of...
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I'll buy some more 7788 and give them a try. I'd hate to change tubes at this point. My triode connection has pin 8 (g3) to anode, not ground). I wonder if that makes a difference. Also, the power supply chokes are nearby, per...
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I guess I need to try out some more samples. Only have a few here. And only one has a long time constant 5kHz ring. Heaters are 6.2Vdc with 20mVrms sinewave ripple at 120Hz. Fed from schottky - L - C. Other side of heate...
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