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richardcooper2k richardcooper2k is offline

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  1. Audionorth
    20th March 2011 09:47 AM
    Thanks for the feedback about upgrades.

    I suspect at some point down the line I will explore the possibility of adding the 0B2 but I am not sure if at this point I will do it or not. . . I 'm in contact with the guy who has successfully implemented it so I will eventually get a photo and parts list once I get my 300Bs completely sorted . . .I'm getting close . . . I have finally figured out the 5U4G arcing problem via learning about effective plate supply impedance specs, max ripple current specs of that first input cap and associated esr. My power supply now looks a lot like the AN Conquest minus the 47R input resistor . . .I added 25R on each anode plate to increase the tx DCR to spec (170R total for the 5U4G) . . .

    I had my own filament supply PCBs made for both the 300Bs and the driver tube. I used the same general design as the kit but added back in the 100uf cap that Brian took out of the manual as a result of a their PCB error (hence designing and having my own built) . . .they work and sound great using BG std 2 x 4700uf with an LT1085 regulator 300R and 100R resistors and the final cap a 100uf 16v BG N type. The only change I made for the driver tube was substituting the 100R for a 75R. I ended up using Schottky 31DQ09 3A as the Cree T0220 package diodes picked up hum . . .which was really strange and took a bit of time to track down . . .but know they sound great and fit nicely . . .

    Thanks for the interstage advice as that is likely the route I will go starting with my DAC next time PCX has a sale that includes transformers/interstages . . .

    Regards and if you are interested in the 0B2 info when I get it I will be happy to pass it along . . .

  2. Audionorth
    6th March 2011 08:58 AM
    Hi Richard,

    Since being literally "banned" by Brian (truth is stranger than fiction) from the AN kits site for calling him on his BS, I am actually relieved to be relying more on the sites I used to frequent before AN kits. However, since this is such a AN specific question I thought I would see if you were willing to give your opinion/experience regarding upgrades. I have the L3, DAC, and AN kits 300Bs.

    I 'm having trouble with arcing rectifiers as I am using a 5U4G and the effective plate supply of the 400v transformer supplied with the kit isn't sufficient so I will be looking to find a custom pair of power transformers built. I'm currently using an NTC to survive until the new power transformers are made. But my point for this e-mail is about upgrading strategies:

    I anticipate my current upgrade path over the next year or two as follows: (after changing out the power transformer in the 300Bs)

    1- upgrade the L3 preamplifier output transformers to either the Supers or Ultimates (copper) -- (I currently have the HiB Improved); or upgrade the interstage transformers of my preamplifier to either the Supers or Ultimates (copper) -- (I currently have the stock kit interstage transformers.)

    2- upgrade the interstage transformers of the 300Bs to either the Supers or Ultimates (copper) -- (I currently have the Marmah stock txs supplied with the kit)

    3- upgrade the output transformers to my DAC (I currently have the HiB improved); or upgrade the interstage transformers to either the Supers or Ultimates (copper) -- (I have the stock kit interstage transformers.)

    Do you have any opinions about the reasonableness of this strategy . . . would you change the order?

    Another way to ask this globally would be is there a generally considered "better" benefit by focusing on upgrading the output tx first (I have either HiB improved in the L3 and DAC and the Supers in the 300Bs already) or the interstage txs? All well okay most parts have been maximized where possible with AN tants, Black Gates, high quality point to point wiring with mostly soft annealed solid silver wire, a custom built attenuator, etc. both copper and silver AN caps. I realize synergy, room and speakers are all relevant as well . . .

    However, do you have any recommendations your willing to share as a result of your experience? I should of sprung for the Ultimates with my 300B output transformers but only got the Supers however, the amps are sounding very good and are dead quiet. . . strangely enough I had custom PCBs made for the 300B filament supplies and using T0220 Crees resulted in Hum and when I removed them, the hum disappeared with no other changes (I replaced them with 31DQ09 (3.3A 90v Vishay axial lead diodes) . . .I certainly can't explain that one.

    Any way, any thoughts about my proposed upgrade path will be appreciated. This is clearly a plan that will be put in place over the next year or two depending on finances and PCX sale prices . . .:-)

    Thanks in advance!

  3. Audionorth
    18th December 2010 08:23 AM
    Hi Richard,

    I just came across this message for the first time tonight. A bit late in my response needless to say. Unfortunately I don't have the full schematic you reference. I periodically talk with "Tubeheadz" from the asylum BB but my tolerance for his narcissism gets over-loaded and I need to take periodic breaks . . .:-)

    I know he is working on adding the OB2 tube as a regulator to replace the Zener in the M2 PS. However, I'm still completing my 300Bs which will be done in the next couple of weeks as well as upgrading my speakers. Same woofer driver but will be using the Accuton 6.5" mid and Raal OEM 70-20XR tweeter. Once all this is complete I will look to upgrade my M2 PS bridge to individual diodes and possibly convert to the 0B2 if Tubeheadz completes it, reports an improvement, and then is willing to share it with me which I assume he will. . .

    That's the current status for me at the moment.


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