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Posts by gibosi

 I have been wondering about how the operating points in my OTL are affected by changing rectifiers... Specifically, Glenn, should I assume that when you designed my OTL with the original transformer and 5-volt rectifier, you used the 3DG4 as your reference? And as it is my understanding that the 3DG4 has a voltage drop of about 25, did you then factor in a voltage drop of 25 to achieve the desired operating points? And further, when you designed Whirlwind's OTL with the...
 To give you a little more to think about, your C3g are pentodes. But as X notes, Glenn has wired them up as triodes in your amp (and mine). :)
Recently received an early Hungarian Tungsram ECC40. To those who are new to the ECC40, it was developed by European Philips as a miniature all-glass replacement for the 6SN7. And thus, with a simple pin adapter, it is plug and play in most headphone amps designed to use the 6SN7 as a driver.   Only Philips and Tungsram manufactured this tube, likely due to it's non-standard 8-pin Rimlock base. In the 1950's, Philips manufactured this tube in 5 different factories:...
 And if you have an amp that uses 5U4-type rectifiers, a HEXFRED from Glenn gives you the best of both worlds in one amp. Having choices is always a good thing, IMHO. :)
HEXFRED   I haven't yet had a chance to directly compare the HEXFRED to any 5 volt tube rectifiers, but I did plug it in and spend some time with it last night. My initial impression is that the HEXFRED is a very fast and transparent rectifier. But upon further reflection, given that the voltage drop is very near zero, it might be more accurate to say that the HEXFRED has no affect on the sound. Nothing is added or subtracted, and therefore, with the HEXFRED installed,...
 I can only wish! lol :)
HEXFRED (For some reason I want to say Hexifreddie! lol) arrived today. Thanks Glenn! :)       From the outside, it is appears to be an octal socket filled full of epoxy (with a rather artistic arrangement of bubbles on top I should add) and it is very solid. Put it in and, of course, it works! But until I have had some time to compare it to my favorites, GEC U18/20 and Cossor 53KU, can't really say how it sounds....
 It really depends on how they have been stored. If there were stored in a temperature and humidity-controlled environment all these years, the boxes would still look new. I have some boxes from the 1940's that look and feel new.
 Thanks Glenn! I am really looking forward to it! :)
 I am quite sure that when these were manufactured they had rhodium pins. And it is important to remember that the plating on the pins, whether gold or rhodium, has absolutely no affect on the sound. These platings were applied because they are resistant to corrosion, and never having to clean pins is a very good thing. However, there is something about gold pins that causes people to go a little crazy... lol. And while I have no proof, I believe that when you see Voskhods...
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