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| Romy the Cat's
personal site dedicated to advanced audio and evolved music reproduction
techniques
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Contemplating now how to organize biasing for 3 singe stages of my 6-chanls amp I was faced the dilemma: do I need to bias my tubes. The 6E5P/6E6P are Russian tubes and it means that are very different right from the boxes. The Milq, driver tubes, be...
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Hi!Could you tell a bit about how does this:"I end up with 360V on B+, 15K plate load, grounded cathode, 160V on plate and -3.5V on grid via a series battery."sound as compared to the normal Milq bias?Thanksbe...
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Well, I would say that “something is wrong” as what you report it is not how it shall be. I had my doubts about the rational to use 6C33C in direct heating coupling but the “danger” in direct coupling uselessly coming from the plate of the driver...
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Thanks for your help Romy. Have a look at this (barely legible) sketch so we have a common reference:This is Channel B First Stage bias circuit. All is identical to your published schematic apart from R9 which I had to increase to get the other sta...
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Hi Romy,Further to my earlier message, I've measured the bias voltages for the driver tubes in all Channels.A -4.3V not adjustableB -13.82V not adjustableC -4.8V not adjustableD -4.2V (ran out of potentiometer travel...may have to adjust a resistor)E...
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[quote user="decoud"]I shall try it; do you suggest it as a test of whether or not mating the Milq with the SH50 screws up the sound irredeemably anyway? Rgds, d[/quote] Nope, it has nothing to do with ability or disability of Milq to drive SH50. Mil...
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Hi Romy
I have a mono completed full range Melquiades and another only with the bias circuit hooked-up.
The bias voltage I get on the 6e5p is around minus 4.4v on both the circuits. This is with the inputs shorted. With the inputs connected to adj...
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[quote user="cb"] Yes, it is imposable to have + 0.4V on the grid, 0.0V at input, with R5 resistor in place and the gas tubes outputting +150V and -150V. My apologies, I meant to say I have minus 4.4v on the grid with the inputs shorted. Then I...
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[quote user="Chirag"]The 6E5P is an interesting device (I did some research after you dropped the "tetrode" hint and bought a few :-)), but the bias scheme with the OA2's is still incomprehensible to me. [/quote]Ok, I will try to explain.
The...
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Thanks ml8, do you know how much it could swing before problems, either due to clipping or grid current?Rgds. be...
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[quote user="Romy the Cat"] Celsius wrote:The problem is that my target is drive a 211 as full amp, and my CD player give a litle bit more than 1v to grid. What do you think 1V x 33times x 2.8 give 93ppV enought to drive the 211. Well, you nee...
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hi RomyNice bias battery gimmick for the el-caps!But, i see the hardcore analogue teams are having a hard time with room modes and time alignment :)I wonder what it takes to admit one day that you can’t neglect DSP anymore, and just having so much ea...
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I've never tried anything but self bias. Do you think fixed bias is better in every case, or does it depend on the output tube?
Paul...
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Hi Romy,Thanks for your response! I have never tried grounding the cathode in any of my tube projects. Even my amp output stages have been mostly cathode biased. But I am going to try grounded cathodes (and the +/- input stage supply) in my next amp,...
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Some people bias 833 at 0V. Some in A1 but to get teh stated powerit must go into A2. Do you or anyone have normal plate curves for 833 instead of that multiampidiocy usually published? Say up to 200mA. Same for 304tl.Outpur tranny--this is the funct...
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Paul, again the diodes are there not because they are diodes and one needs a diode action there, but because they wanted to substitute cathode bias resistor with something that would have a big static resistance (to set the DC point and stabilize) an...
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Hm, in an idea come to me today I think I will try very soon. Why do not combine my Injection Channels with Horizontal Bias Channels? Since my Injection Channels have HF transducers then it will introduce a tremendous lobbing BUT… But my Injection Ch...
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Since renewing all tubes in both ML2s, over the period of about 3-5 minutes, the V2 bias on one of the amps cylcles between .27 and .33VDC. Is this behavior indicitive of a defective 6C33C?jd*...
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ml8 wrote:"This few tubes was 6E5P, 6S45P (which i've found a little better for my single-stage amp that 6E5P) and... perfectly god-like sounding (output beam tetrode) 6P6S!!! Triode-connected, for sure. Absolutely the MOST clear sounding driver, and...
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Yes, it is imposable to have + 0.4V on the grid, 0.0V at input, with R5 resistor in place and the gas tubes outputting +150V and -150V. My apologies, I meant to say I have minus 4.4v on the grid with the inputs shorted. Then I unshort the ...
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Romy,Could you help me understand your biasing scheme with this version? I thought I understood the original Milq circuit - but the only channel that looks like that to me is the D channel. I don't get A and B at all! what is the 50 ohm resistor doin...
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Romy, in this situation, 70' of 8 ga. cable is effectively a variable reactive load and a sink. If nothing else, voltage drop will play a part here, 8 ga. notwithstanding. Whatever you use to span a gap like that will probably need to be biased to ke...
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Romy,I looked at your Melq schematic : http://www.goodsoundclub.com/PDF/Melquiades_SET.pdf regarding the 6E5P bias. Would it be simpler to use two alkaline battery in place of R5 to provide 3V , or 3 Rechargeable for 3.6V in place of R5 ? Did you tr...
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Hi Shannon and thanks for the answerI guess i have to try it when i m able to build itRegardsTom...
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Now we're talking!Romy, I have long nodded in agreement with your observations about the critical nature of "plate loading". Meanwhile, my own recent experiments have shown that dialing in voltage and current is just as Big a Deal with SS as it is w...
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Romy, thanks, as usual, you seem to have been right. The system is on and I just checked V2 voltage; its way off, above .4VDC, so I grabbed a hot pad from the kitchen and rocked the V2 tube. The socket made the familiar a dry creaking sound and see...
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No, I did not try to use grid chokes. The setting for Milq was flowing: the highest voltage in the gas tube and the highest value of resistor to the grid. Frankly there is a LOT of mystery how it all works out together and how it all inflicts s...
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[quote user="be"]ml8, could you tell what voltage and anode load you used the 6s45p without bias? What about grid stopper, etc.?[/quote]Kinda of 100-110 V on a plate. I didn't measure current cause by looking at curves i was confident that i'm not ov...
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Hi all ! I thought about this resistor bias idea that Chris proposed , and found some some problems here . One of them discovered Chris himself - it is a big serial resistor in the grid chain , and it can cause not only HF rolloff ( it isn't a big pr...
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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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