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| Romy the Cat's
personal site dedicated to advanced audio and evolved music reproduction
techniques
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Romy,I hate it when I realise I need a different transformer...The following is not an ideal solution because it breaks one of the Melquiades design features, but may be worth trying - cathode bias on the output stage? You could burn up some vol...
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Options are limited here... looking at the schematic, you're sorta pinned in by the biasing topology used. One typical method would be to use a resistor divider network at the input grid to the 6E6P. Problem is, this results in a huge bias offset. By...
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Do you mean a battery bias , Brian ? We didn't try it because of 1 V bias voltage - I don't know if the battery with this voltage does exist . I know only 1,5 V and 1,2 V cells ...... maybe using some chemical reactions we can obtain 1 V or little le...
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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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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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Thanks Romy,It is now fixed. I have left Channel B the same apart from adding a 390k positive bias resistor on the positive signal line (between C1 and R5) connected to the 14k resistor that also connects to Channel C and F. A 402k would have been ...
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Grid leak bias is not reliable itself . Grid current is very low and grid resistor is very big , the circuit become very sensitive to all destabilizing factors - capacitor leak , humidity , temperature . And when we apply a big input signal to t...
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With my limited experience of using pentodes (primary as phono corrector first stage) I think that the most mysterious in them is power supply of bias to "other" grids. Looking at the Milq schematics it is obvious that I pay too much attention to th...
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Decoud, When and if you but Milq then I would encourage you to make an experiment. Disconnect all basing schema that I implemented for Milq and bias the driver stage with regular fix, buttery or cathode bias. The amp will be working perfectly fine. N...
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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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Jim, yes, I use the 6E5P as triode, I never tried tetrodes, never has needs to do it. I have somebody tried them as tetrodes and commented negatively about their sound. I do not know if it is true – it what “they say”. Ironically I do not like how th...
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Interesting. I think that with testing just for:
- gain - bias - distortion - power output - hum level balance
It is not necessary give an objective picture about resources of a tube. We can monitor the change rate in the tube bias as some ...
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[quote user="G"]Should
the grid bias voltage change when I adjust VR1? In my case it does – if I keep
increasing dc on inputs I can get to -1.5v on the grid and around 60v on B+.[/quote]
Nope, it should not, well it is and it is not.
Are you s...
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[quote user="anthony"]I plan to
build a fullrange Melquiades for a friend and then if that works out the DSET 6
or 7 channel version for myself. [/quote]
That is very good approach in my view. The
problem is in this approach that you have t...
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[quote user="N-set"] I do have some serious concerns with respect to my design, the LF stability beeing the most important one (before we even approach talking about the Sound...if any); you may rememebr I was asking you about the stability and relia...
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I have huge AMCC800A cores for two such transformersand good winders with HV experience. I also have a lot ofquiality coax cable, good to few kV for the chassis hook-up.Again, if somebody is willing to take care of that, I can lend.I'm myself 3000km ...
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Hi Romy,What a busy year just gone! Finding enough time to just sit down and get the DSET's going has been impossible, but I have time now and have started the process.At the moment I am introducing some high voltage to the first amplifier chassis, ...
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[quote user="KOTriode"]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 ...
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[quote user="AnonymousUser"]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 sup...
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[quote user="N-set"]Romy, may I ask you why you've employed an autobias on 6E5Pin Milq's MF rather than your biasing technique (if there is any reason at all)?[/quote]If you look at the page #13 of the Milq DHT thread then you will see that the first...
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[quote user="KOTriode"]Romy,I have good confidence that it was the tubes and not the circuit. I have checked the cathode driver that bias the 6C33C and there was not any problem. Sure if the cathode bias failed, the 6C33C current will shoot way u...
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[quote user="KOTriode"]Romy,The normal bias for the Golden Grid tube for 200V Plate at 200ma is about 70V-80V for the good tubes, the bad tube read 0ma at this bias, when drop to -30V it start reading some current, but can't get to 150-200ma current ...
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Totally disappointed today, while I was listening to music, the left channel make a small pop and quit. The bias meter showed about 25ma bias instead of 200ma. Test the tube on bench showed that the tube current stay about 25-50ma max. This tube is g...
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[quote user="deemon"]Do you mean a battery bias , Brian ? We didn't try it because of 1 V bias voltage - I don't know if the battery with this voltage does exist . I know only 1,5 V and 1,2 V cells ...... maybe using some chemical reactions we can ob...
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After swapping all the tubes between the left and right amps, the cycling bias current issue (mentioned here in a previous post) seems to have settled.I now have another question, which I hope other ML2 users might answer; first the context: These am...
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Thanks, Jim, and thanks to everyone who replied in direct emails. Summarizing what was advised to me it looks like as now the input impedance of the amp is around 4.5K. That was roughly what I would like to have, though I would like to go even furthe...
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The 100W+ SE is pretty much uncharted teritory, not to mention Bass SE. Who can speak about the Sound?Only that who tries.Paul, the diodes in Chimera are for biasing purpose, but I agree, here there is no cathode feedback not ot loose power,the whole...
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[quote
user="anthony"]Hi Romy,
Further to my earlier message, I've measured the bias
voltages for the driver tubes in all Channels.
A -4.3V not adjustable
B -13.82V not adjustable
C -4.8V not adjustable
D -4.2V (ran out of potentiometer travel...
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I was searching for an answer why squire wave is so screwed and I was advised by the site’s visitors that it is due to HF restriction of my channel. My HF response does look too low to me – the 23kHz; with all my ultra low capacitance magnetic I ...
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I read one more page from the Tenor description, before the author begun to talk about sound. A correction need to be made, from the first pages I understood that the amp use 6N6P driver but on the next pages it was not the case. Perhaps I confused s...
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