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BamaMike

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    VRD Tube Biasing

    in Talkin' Tubes

    Posted

    On 12/9/2019 at 2:20 PM, rplace said:

     

     

     

    Brining this old thread back to life as it has lots of info for my question. I found this while searching for an answer I can't yet find. I do have an email out to Craig at @NOSValves but figured with so many VRD owners here you all might be able to help.

     

    I've got some EL34s that I want to try just because I have them on hand and never run anything but KT88s in my VRDs. I've acquired some vintage GE 5U4GB rectifiers so I'm good there. I have my original manual from when I bought the VRDs new. In it with respect to biasing it says bias them at .50-.65 and Craig said he ran his at .55. I've always kept mine at .55 since I bought them. This thread seems to suggest .70-.80 is the range.

     

    1. So what is the proper bias for KT88s and if EL34s need to be run lower what is a good number for them?
    2. Was there a few different version of the VRD thus my manual says .50-.65 the one quoted above says .70-.80?
    3. If there are two different types of VRDs and mine are the .50-.65 variety AND EL34s need to be run lower what would be a good number? 
    4. I've got some Russian military 6P3S-E (GL6GC equivalent ) inbound, what should I run them at based on the above answers?

     

    This thread has my curiosity as well. I'm running Quicksilver Silver Mono's and my PAIR of KT88's COMBINED bias is around .80 VDC. I think I'm at .78. I was told a KT88 alone should be around .40 so .80 made sense and this is what Quicksilver told me as well. Just curious if the above advice was for a PAIR of tubes. 

     

    Also - Golden Lions were red plating on me at this bias so I switched to JJ's on Quicksilver's recommendation and no issues since. They DO NOT recommend Golden Lions. 

    Tube Amp Kit Recommendations

    in Talkin' Tubes

    Posted

    On 12/3/2019 at 6:19 PM, thebes said:

    No.  Just contact him via this place. He's our own Tube Fanatic.  If you do a search he's already got some of his schematics and builds posted here. Often he includes a parts list, which is very helpful.

     

    Fellow hobbyist and great guy.

     

    If you are not up for building one, I think he may still have a few of his creations left. Due to parental pressure (his wife!) he's been forced to sell off some of his babies.

    Roger that!

     

    Thanks

    Tube Amp Kit Recommendations

    in Talkin' Tubes

    Posted

    On 11/29/2019 at 6:54 PM, thebes said:

    Obviously your better half can read a schematic so why not build one of Maynard's creations?  The parts are readily available, he doesn't use exotic tubes and you can design you own platform. I've done amps in acrylic, wood, a cake pan (yes a real cake pan) and I'm thinking my next build will use pottery or stone.

     

    Also his designs usually incorporate a circuit which serves as a preamp and or an attenuator.

     

    Unless you need tons of power, you will be thrilled at how they sound, and shocked at how cheaply they can be built.  Schematics are free, free, free because Maynard's one hellava guy:

     

    image.jpeg.cc65192811aba7d6b6a3f40c1c743b47.jpeg

    Does he have a website or ???

    Tube Amp Kit Recommendations

    in Talkin' Tubes

    Posted

    On 11/13/2019 at 6:57 AM, BadChile said:

    Couple other thoughts:

    Bottlehead is releasing a pair of 2A3 based monoblocks for under $2,000 in the coming months but I can't find the link to the amp (early morning / lack of coffee / general tiredness).  If I recall correctly they're priced under $2,000 for the pair.  Will edit this post if I find information on the amps.

     

    The Elekit amps are well finished and well reviewed.  I built and run a TU-8200 (6L6GC based, also runs EL34, KT88 and associated tubes), and if in the states, now that VK ships these out with JJ tubes I suspect they'll gain more of a following as the 12AU7 that was shipped previously was a major weak link in the amp as-built.  In addition to the TU-8600 (300B based amp) listed above, there is a soon-to-be released single ended TU-8800 based on the KT88 that produces slightly more power than the TU-8200 and has a tube cage unlike the TU-8600.  Additionally, the upgraded transformers are available for the TU-8800 at launch while TU-8600 owners are still in a holding pattern.  As a bonus - headphone tap off the tubes so all Elekit amps double as a quality headamp.

     

    Note that Bottlehead and most of the Elekit prices include tubes with the exception of the TU-8600.  But the reality is you can't go wrong going down this path rabbit hole of DIY audio.  I remember silently laughing at people who spent $60 on four coupling capacitors and now here I am one of them....

     

    Thanks... I'm headed off to find more info.

    Tube Amp Kit Recommendations

    in Talkin' Tubes

    Posted

    16 hours ago, jimjimbo said:

    You can say that again......just looked at her FB page......

    LOL... thanks.

     

    Plus - She hates shopping, loves martial arts and action flicks, wears little to no make up and does not carry a purse... AND... she shares my love for fine bourbon and tequila. HA!

    Tube Amp Kit Recommendations

    in Talkin' Tubes

    Posted

    So my wife, the electronic technician, recently diagnosed and repaired an issue with one of my Quicksilver Silver Mono Blocks. God bless her! So now she wants to build an amp or a pair of mono blocks. I have started researching kits but thought I would ask you all for any recommendations. Want something that looks as nice as it sounds.

    20191101_175435.jpg

    output.jpg

    • Like 1

    Preamp Recommendations for my QuickSilver / Cornwalls

    in 2-Channel Home Audio

    Posted

    Sadly, one of my mono blocks went down in "flames". I put new Golden Lions in and re-biased. They were red plating so I switched back to the tubes that came with it. About 30 minutes in the fuse blew. I replaced it and during warm up one of the KT88's flared up! POP! Fuse gone. I need to find a schematic to test the internals before I throw another set of power tubes in and fire it up. :(

     

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