xlr8or Posted April 17, 2021 Share Posted April 17, 2021 (edited) 6 hours ago, Ihearmusic said: I could have put a set of KR 300B in for him to compare against the Gold Lions but since a pair of the KR cost as much as the MingDa, there was no point. I run KR 300B in my amp and the difference it made is phenomenal. No going back from here. I have KR Enterprise/Audio 300B balloon shaped, 300BXLS and VV32B toobs. I find them all to run particular well with 300B amps that run at higher B+ (400-450V) and higher plate current (100mA). Their specs indicate they should be run at these higher power dissipation values as average operating conditions when compared to 'standard' 300B specs such as the Genalex PX300B that has the same values specified as the absolute maximum operating conditions. Some of these specs also indicate the preferred primary output impedance for the tube, which is a bonus. Edited April 17, 2021 by xlr8or 1 Link to comment Share on other sites More sharing options...
Ihearmusic Posted April 17, 2021 Share Posted April 17, 2021 I have found that certain 300B tubes do not like high B+. They are prone to arcing due to their construction of the anode, grid and cathode interfacing so to speak. 1 Link to comment Share on other sites More sharing options...
xlr8or Posted April 17, 2021 Share Posted April 17, 2021 (edited) Yes, fully agree RE the red plating and arcing. Several TJ 300B/n mesh plates and Shuguang ST shaped 300B/a's showed symptoms of this not operating anywhere near their maximum limits. You've got to be really conservative with dialling in the bias to be well less than 60mA when the B+ is anywhere near 400v. Fortunately, Eric's designs are tuned in using 350v for B+ and 50mA allowing the Chinese variety to be used safely. For peace of mind I checked with New Sensor when the PX300B was first introduced into the market. I was advised back then by one of their chief senior engineers that the tube can operate safely running at 400v and 60mA, which I can confirm has been the case ever since running tbe PX300B for a few years now without any issues. With the Chinese tubes in there you had to be like a hawk. Any intermittent red plating and I was up in a flash to turn the power off hoping to save the tube. This was a most uncomfortable listening experience watching for the tube plates to turn red. Edited April 17, 2021 by xlr8or 1 Link to comment Share on other sites More sharing options...
RoHo Posted April 18, 2021 Share Posted April 18, 2021 On 16/04/2021 at 8:18 PM, crtexcnndrm99 said: There’s fair talk of interstate transformers here so... Any of the tube gurus know of some good el84 or kt88 circuits that use interstate transformers? Looking for something ‘more iron than glass’ like above, and in the vein of Sakuma San I'm no guru but my 2 cents worth is that the more difficult an output valve is to drive, WRT peak drive volts and Miller capacitance, the more likely an IT will be better. An EL84 is real easy to drive, the amps are usually quite cheap and so using an IT will blow the budget for no improvement. EL34 and KT88 need more drive volts but still significantly less than a 300B. The price of the valve comes into it as well. With 300B's being much more exxy the cost of an IT is less as a % of total amp cost. So you never see IT used with EL84 and I can't remember seeing an EL34 or KT88 amp with them. But...go look at Lynn Olson's Karna amp for an example of lots of transformers. Push-pull 300B, 3 stages all transformer coupled. http://www.nutshellhifi.com/triode2.html 2 Link to comment Share on other sites More sharing options...
doogie44 Posted April 18, 2021 Share Posted April 18, 2021 On 17/04/2021 at 11:28 PM, xlr8or said: With the Chinese tubes in there you had to be like a hawk. Any intermittent red plating and I was up in a flash to turn the power off hoping to save the tube. This was a most uncomfortable listening experience watching for the tube plates to turn red. There is a medical condition called 'orgasm-induced headache'--it can be quite severe. This 300B experience you mention sounds remarkably similar in the listening leadup...! 2 Link to comment Share on other sites More sharing options...
Odyssey Posted April 19, 2021 Share Posted April 19, 2021 What do you say.... should I ask Eric to remove the lettering on the gold front panel? Yes I opted for the gold instead of silver... for a change. 1 Link to comment Share on other sites More sharing options...
BLAH BLAH Posted April 19, 2021 Share Posted April 19, 2021 Just now, Odyssey said: What do you say.... should I ask Eric to remove the lettering on the gold front panel? Yes I opted for the gold instead of silver... for a change. Oh I do like that gold front panel!...I wish I had that option available when I ordered my bespoke 300B SET from Eric! Personal choice in regards to the front panel lettering...I do not have any on my 300B...and it makes no difference to me in audio function choice... Visually no front panel lettering imo gives a nice clean uncluttered appearance... What about the dials and power switch?!? Will they be sourced as gold or another colour?!? Link to comment Share on other sites More sharing options...
dwbasement Posted April 19, 2021 Share Posted April 19, 2021 Mmmm... gold would be hard to get nice knobs and switch to match well. 2 Link to comment Share on other sites More sharing options...
Odyssey Posted April 19, 2021 Share Posted April 19, 2021 5 minutes ago, BLAH BLAH said: What about the dials and power switch?!? Will they be sourced as gold or another colour?!? They will be in gold as well. 1 Link to comment Share on other sites More sharing options...
Odyssey Posted April 19, 2021 Share Posted April 19, 2021 Now Eric ask me if I want the irons painted in Satin semi gloss or gloss black. I feel like asking him to paint it gold lol. Link to comment Share on other sites More sharing options...
BLAH BLAH Posted April 19, 2021 Share Posted April 19, 2021 31 minutes ago, Odyssey said: Now Eric ask me if I want the irons painted in Satin semi gloss or gloss black. I feel like asking him to paint it gold lol. 3 Link to comment Share on other sites More sharing options...
xtiva2000 Posted April 19, 2021 Share Posted April 19, 2021 Eric has changed my driver tube to 6DN7/6EW7 and been testing 6EW7 today and a little disappointed with its soundstage. Bass extension and treble detail, still was very good. Overall tonality or separation has not been affected much but soundstage width suffered .... in my opinion... Aesthetically it looks good with the socket converter but might have to give this one a miss, as genre I listen is 99% classical music... Will now test 6DN7 for a day two and report back. 1 Link to comment Share on other sites More sharing options...
Odyssey Posted April 20, 2021 Share Posted April 20, 2021 How's this now Blah Blah? 1 1 Link to comment Share on other sites More sharing options...
BLAH BLAH Posted April 20, 2021 Share Posted April 20, 2021 12 minutes ago, Odyssey said: How's this now Blah Blah? 3 Link to comment Share on other sites More sharing options...
dwbasement Posted April 20, 2021 Share Posted April 20, 2021 Looks good Matt! 2 Link to comment Share on other sites More sharing options...
Midget Posted April 20, 2021 Share Posted April 20, 2021 My McChanson 10 2 Link to comment Share on other sites More sharing options...
xtiva2000 Posted April 20, 2021 Share Posted April 20, 2021 1 minute ago, Midget said: My McChanson WOW looks great is this with Meze transformers? Link to comment Share on other sites More sharing options...
Odyssey Posted April 20, 2021 Share Posted April 20, 2021 Very nice looking @Midget !!! What color is the front plate? How long did you have this? It's gorgeous. This is with marzE transformers all the way. Link to comment Share on other sites More sharing options...
Odyssey Posted April 20, 2021 Share Posted April 20, 2021 Knobs are in and Eric ask, blue or red LED light above the power switch? What do you think? Link to comment Share on other sites More sharing options...
BLAH BLAH Posted April 20, 2021 Share Posted April 20, 2021 (edited) With the gold face plate I would be tempted to go the blue LED...for the CCC effect...Cooler Colour Combo! Edited April 20, 2021 by BLAH BLAH Link to comment Share on other sites More sharing options...
dwbasement Posted April 20, 2021 Share Posted April 20, 2021 May be ask Eric to take photos with red and blue led for you to decide... should be easy to do. 1 Link to comment Share on other sites More sharing options...
xlr8or Posted April 20, 2021 Share Posted April 20, 2021 (edited) Forget the red and blue and go for the green or orange. Do you want your listening room to become the red or blue light district of the town? Edit: Also added orange. Edited April 20, 2021 by xlr8or 2 1 1 Link to comment Share on other sites More sharing options...
BLAH BLAH Posted April 21, 2021 Share Posted April 21, 2021 1 hour ago, xlr8or said: Forget the red and blue and go for the green or orange. Do you want your listening room to become the red or blue light district of the town? Edit: Also added orange. Oh yes the green/orange LED appeals as well... Orange LED to compliment the gold front plate... Green LED to match the envious eyes of onlookers! :)... 2 1 Link to comment Share on other sites More sharing options...
dwbasement Posted April 21, 2021 Share Posted April 21, 2021 I actually prefer no led at all, just the tubes glow! Unfortunately Eric can't do that... Link to comment Share on other sites More sharing options...
Ihearmusic Posted April 21, 2021 Share Posted April 21, 2021 Go for Blue. You can tone the blue one right down so it is not blinding but you can easily see that is on. Since the blue led is clear when not powered up. With the other colors you can not tell, should sun light hit them, whether they are on or off. Plus blue is neutral. It is not a stop and go thingy... 3 Link to comment Share on other sites More sharing options...
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