gartenman Posted February 6, 2010 Share Posted February 6, 2010 Here again is an assumption, the RCAs have more gain.? be sure you didn't put the 12AX7 tube in the 12AU7 slot in the Peach, but if they are in the right slots than your assumption is about more gain is true, those RCAs you put in from Brent are very good tubes, all 4 would have cost close to $200 whereas the 4 JJs cost around $60...you get what you pay for (usually)... do you like the sonic improvements? tell me what changes you hear other than the increased gain... Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 6, 2010 Author Share Posted February 6, 2010 Humm, describe sound.... 1) A little more bass, can feel it in the chest without cranking it up. 2) The drum brushes on cymbals come out a bit more, can hear them being drug across the cymbal 3) The "circle of sound" floating in the center stage is lower by about a foot or so, in my case a good thing it was a little too high at my sitting level. It's now just a bit higher then the top of the Belles. 4) Seems like the left and right channel material is more discreet while the center stage remains fixed. "be sure you didn't put the 12AX7 tube in the 12AU7 slot in the Peach"; I have not touched the Peach yet, only the amp. Quote Link to comment Share on other sites More sharing options...
gartenman Posted February 6, 2010 Share Posted February 6, 2010 1) A little more bass, can feel it in the chest without cranking it up. 2) The drum brushes on cymbals come out a bit more, can hear them being drug across the cymbal 3) The "circle of sound" floating in the center stage is lower by about a foot or so, in my case a good thing it was a little too high at my sitting level. It's now just a bit higher then the top of the Belles. 4) Seems like the left and right channel material is more discreet while the center stage remains fixed. Sounds like a good description, the improvement in the soundstage you refer always amazes me along with bass and treble definition and extension Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 7, 2010 Author Share Posted February 7, 2010 Today I replaced the Valve Art KT-88s with the Gold Loins. Very subtle change noted after biasing to 0.60, perhaps the bass notes 'hold' a little longer. Listening to Dire Straits B.I.A. XRCD. I do like the GL's glow reflecting off the polished surface of the VRD-St. I'll let them settle in for a while. The change made by swapping small signal tubes was very dramatic in comparison. I appreciate the earlier tip provided about the tube receptacle sockets, I checked and sure enough the VA pins had them spread open and would have had a loose fit. Using drapery hooks I tightened them up, any hints on a better method? Quote Link to comment Share on other sites More sharing options...
gartenman Posted February 7, 2010 Share Posted February 7, 2010 i have a friend who is a dentist and he gave me one of his instruments that works great but if the method you used worked i'd stick with it...sounds like you troubleshooted into finding what i think is a very good idea...i'd give the GLs 50 hrs with 100hrs recommended before making my final decision, replacing power tubes does not make as big a difference in tone as changing the signal tubes as you have noted but they will make a discernible difference in tightening bass, improving treble extension and soundstage, i know 100 hrs seems like a lot but i think those are new tubes and from what i've experienced with them and read they really improve as they burn in, (not unlike a new car's engine)...if you do a search about the GLs online you'll see what i mean about their improvement with time and the general consensus on how well they are liked... i'm happy with your progress... Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 7, 2010 Author Share Posted February 7, 2010 After about an hour of play I turned the pre-amp off and left the amp powered up thru the Superbowl. The bias had drifted only about .001-.004 over the 4 tubes. I shut it down and will check again when I get another opportunity in a couple of days. I need more info. Somehow I got the impression that the rectifier tubes provided the power/current to the output tubes. If that's the case then...huumm gotta do more goggling on the topography and exactly what biasing is. Quote Link to comment Share on other sites More sharing options...
gartenman Posted February 7, 2010 Share Posted February 7, 2010 Craig at NOSValves can explain it to you better than I ever could. I'm sure That the tubes only drifted that much is very good. 50 hrs is not set in gold. They may wake up after 17 hours. Debatable topic, although conscience is tubes sound better after burn in Think of a power supply in terms of a water supply. The transformer is your big lake... where all the water (power) comes from. All the water to your town has to pass through a big pipe. The rectifier is that pipe, all current going to the output devices passes through that rectifier. Amps deal with slew rate, which is how much instantaneous power demand the power supply is capable of delivering. Everything is fine with the water supply in your town as long as everybody is using water at a reasonable rate. But, what if every single person in that town decides to open their taps simultaneously? You can imagine the demand that pipe (the rectifier) is going to have to meet. Well, that's slew rate. If your pipe isn't big enough, you're going to have unhappy water customers. And if your rectifier isn't big enough, you're going to have unhappy output devices. And that's why rectifier tubes do make a difference. The purpose of an amplifier in the basic sense is to take a small AC current and AMPLIFY it into a large AC current (going to your speakers). There are two basic ways to do this in modern amps, using solid state transistors or vacuum tubes. Both require that your AC wall current be converted into a smooth DC voltage. Tubes and transistors both use the small AC signal as sort of a gate to let this larger DC voltage pass through, think of it as opening and closing the valve of a firehose--coincidentally why vacuum tubes are called 'valves' in the UK. If the power tube bias is incorrect for the power tubes being used, they can sound bad and/or can literally burn themselves out by dissipating too many watts, sometimes with disastorous effects. Setting the power tube bias within specs will make the tubes last longer and will also help the amp to sound its best. Of course, like most everything else, this is a subjective topic, and everyone seems to have a different opinion about what is best. Put it all together and you see how the tube rectifiers power handling capacity coupled with slew rate demands and properply biased tubes all effect each other dynamically... Quote Link to comment Share on other sites More sharing options...
frankphess Posted February 8, 2010 Share Posted February 8, 2010 Here again is an assumption, the RCAs have more gain.? be sure you didn't put the 12AX7 tube in the 12AU7 slot in the Peach, I think you may mean "VRD and not "Peach" as there are no 12AX7's or 12AU7's in the Peach. The Peach takes 6922/6DJ8's and or a 6H30 depending on the version. Quote Link to comment Share on other sites More sharing options...
gartenman Posted February 8, 2010 Share Posted February 8, 2010 Here again is an assumption, the RCAs have more gain.? be sure you didn't put the 12AX7 tube in the 12AU7 slot in the Peach, I think you may mean "VRD and not "Peach" as there are no 12AX7's or 12AU7's in the Peach. The Peach takes 6922/6DJ8's and or a 6H30 depending on the version. my bad got mixed up which we were talking about Quote Link to comment Share on other sites More sharing options...
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