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  1. #1
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    Default Interesting Viking DR clone developments

    So, I'm not sure if I had mentioned this before, but right after I finished recording the first song (not the Gries demo), my Viking DR clone (we're calling it the ODR, for Overdrive Deluxe Reverb..:) ) died on me - well..it wouldn't power on. After a few emails with Eric, pulling out the fuse and putting it back in, it came on and seemed to work fine. I was using TAD 6L6s in it at the time, since Eric had beefed the amp up to take them and a SS rectifier. But, since I was using the Suhr reactive load, I had the master (its a PPIMV) wide open, and the volume at edge of breakup (I guess around 6 or a tad higher), doing take after take.

    Eric seemed to feel that with the bigger tubes and the SS rectifier, what I had done was ill advised, and suggested I cut down the MV. So in the second song, I had the MV at 6, and everything else about the same. The amp didn't blow, but the power tranny was blistering hot after an hour and a half. Eric then suggested that given my preference for running the amp wide open into the Suhr, I'd be better off using 6V6s, and using a 5Y3 rectifier to lower the plate voltage - and then rebiasing but not too hot, preferrably on the cool side.

    So...long story short, I found a couple of NOS RCA 5Y3s online (big risk, I know!) for 50 bucks, and got them. I then popped in a set of Brimars I've had for years, so not exactly NOS, but they were when I bought them. But then, I haven't stressed them at all, so I expect they'll still last a while. Anyway, I biased them at about 19ma on average (they're about 2 ma apart now, which I guess isn't too bad).

    Bottom line - wow!!!! Its a different amp altogether. The clean is much softer, rounder and sweeter, and reminds me of the '64 DR I used to have many moons ago. The OD section has taken on a slightly different character. Its not as immediate to the touch, and almost a tad more forgiving, but very, very sweet - and less fat. Far better in some ways, but perhaps a little less D-like - I like it though. I think I've lost some power, so its probably putting out less than 20W, but thats not relevant to my application.

    That said, I do miss the fat 6L6 tone.....

    FWIW...:)

    Srini

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    I'm glad you worked it out, Srini! Sounds like it sounds great!

    And then if you really want fat 6L6 tone, get yerself a Twin Reverb. Oh, but you better get some earplugs for the neighbors too.
    Some contend that rock 'n roll is bad for the body & bad for the soul
    Bad for the heart, bad for the mind, bad for the deaf & bad for the blind.
    It makes some men crazy and they talk like fools.
    Makes some men crazy and they start to drool.

  3. #3
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    Hahaha...thanks, Stan! And don't forget a new back for me - basically a new body for me - if I try to move that Twin anywhere! But, seriously, I think I can still use 6L6s if I put the GZ34 recto tube back in (as opposed to the SS recto) and bias the TADs somewhat cool, and make sure the MV doesn't go past 5. Oh..and also, practice the hell out of my parts so I get them down in as few takes as possible and turn the amp off! Eric did suggest one more option, which is a mod, and that is to add switchable cathode biasing. Apparently that will lower the plate voltage even more. Thats probably why the Gries seems to take a 6L6 with no problems (its cathode biased), and Dave said to think nothing of running the master at 10, which I do for extended periods of time. So, in a sense I do have the fat 6L6 one, only in a single ended format, which can be a beautiful thing in and of itself.

    But, I always thought that single ended amps inherently ran hotter anyway. Hmmmm....maybe the good Capn will enlighten us..:)

    Srini

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    Call me a flake!

    So, taking a break from recording, I'm sitting in my recliner, plugged into the Viking and just playing along with the iPod and TV and stuff, as usual. The amp was sounding very sweet and all, but a touch anemic to my ears. I figured I needed an A/B test, or as close to one as I could get. I swapped the 5Y3 for the SS recto and put the TAD 6L6s back in and biased them at roughly 33.5 ma - and they were almost the same.

    After about a 20 min gap, I was afraid I wouldn't remember the 6V6 tone, but holy moly!!! The old magic was right back! Fat, muscular, touch sensitive......I guess I'm a hard core 6L6 guy. I guess I'll just keep the MV down a bit while recording and take frequent breaks, but I can't see going back to 6V6s again.

    Tell me I'm not weird!

    Srini

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    You're not weird. You're pretty normal for a hypersensitive tone freak.
    Some contend that rock 'n roll is bad for the body & bad for the soul
    Bad for the heart, bad for the mind, bad for the deaf & bad for the blind.
    It makes some men crazy and they talk like fools.
    Makes some men crazy and they start to drool.

  6. #6
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    Quote Originally Posted by Srini View Post
    ...I always thought that single ended amps inherently ran hotter anyway. Hmmmm....maybe the good Capn will enlighten us..:)

    Srini
    Single ended Class A amps are inefficient and run hot, which means the OT needs a lot of iron to dissipate the heat.

    As you get into the 10-15 watt range, the single-ended transformer gets very expensive, which is why you rarely see a single ended amp over 15 watts as a result.

    Above 15 watts the more efficient Class A/B in push-pull design is usually employed with a less beefy (less expensive) output transformer.

    Srini, Another option might be to fit a cooling fan in the back of your amp to remove some of that heat.
    Last edited by Captain Bb; 05-13-2015 at 06:36 AM.
    I'm a riddle, wrapped in a mystery, inside an enigma.

  7. The Following User Says Thank You to Captain Bb For This Useful Post:

    Srini (05-13-2015)

  8. #7
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    Thanks, Cap'n! I like the cooling fan idea for the Viking, which by the way, is an A/B push-pull (I think thats what Deluxes are). Eric did beef it up to take 6L6s, so I wonder what got it so hot that first time I recorded with 6L6s. I'll just keep the MV no higher than 6 from now on, and take frequent breaks. His PPIMV is so well implemented that you notice absolutely no tone change until you get it down to around 3.

    Oddly enough, my single ended amp, the Gries, was also intended to take a 6L6 tube, which it uses. I've had it on for hours and, yeah, it gets somewhere between warm and hot, but its built like a tank!

    I'm going to get a small fan, and just aim it at the PT in the Viking....great suggestion, thanks!

    Srini

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    Haha Stan! I need to stop obsessing about tone, and just play more.

  10. #9
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    Hah! I know where you're coming from, my friend. I can't ever play without getting analytical about my tone. The best I can do is to try not to obsess over it. But like you, I do have a love for those big glass 6L6 bottles.
    Some contend that rock 'n roll is bad for the body & bad for the soul
    Bad for the heart, bad for the mind, bad for the deaf & bad for the blind.
    It makes some men crazy and they talk like fools.
    Makes some men crazy and they start to drool.

 

 

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