PRS Archon 100 biasing

Discussion in 'Amplifiers' started by Lyric, Oct 11, 2019.

  1. Lyric

    Lyric New Member

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    Hi everyone,

    I purchased some new power tubes from Tube Depot online and received them today. I went with Tung-Sol 7581a and not to be confused with the 7581. I checked with PRS Techical Support prior to buying the power tubes to make sure they’d be good to run and I was given the thumbs up by Sean with PRS Technical Support.

    Anyways I got the power tubes installed and I had to make the slightest adjustment to get them close within 30 +\- via PRS recommendations. Anyways here is a short less than 1 minute clip of the bias adjusted. I’m curious to know if these power tubes are close enough within spec for being matched or are they to far off? Are these acceptable? I was only slightly concerned with the power tube that’s
    around 26, almost 27.



    Thank you and appreciate all the feedback
     
    Tony Hayek likes this.
  2. DreamTheaterRules

    DreamTheaterRules New and improved member

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    So, I’ll preface this with a disclaimer. I’m not amp building guru, although I play one on TV.

    That said, I can’t answer your question, because I’m not sure how closely they were supposed to be matched. It seems to me, they should be closer than that. But maybe not...

    That said, several high end amp builders have gone on record saying that they intentionally want a difference in the two tubes (or two pairs), and one has even said that they have a particular amount of mismatch for which they test and install tubes when the amps leave the factory. The mismatch affects the clipping wave form and they actually have a preferred amount of mismatch that they believe makes their amps sound the best!

    Other amp makers tell you to get tubes matched as closing as possible and they intentionally mismatch the specs on the other side of the power tubes to create their preferred asymmetrical clipping.

    I’d ask the store if that was within their spec, and then I wouldn’t worry about it. Then maybe ask PRS Customer Service if that match is close enough. It might even sound better.
     
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  3. bodia

    bodia Authorities said.....best leave it.....unsolved

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    I’m not sure what the tolerance is really supposed to be on “matched” tubes. I had a similar experience on replacing tubes on my HXDA, they were about 4 off. And that was with an NOS set of Mullards.
     
  4. Lyric

    Lyric New Member

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    Sounds good, I’ll shoot Tube Depot the video ask them what they think and see if it looks ok. I’ll shoot PRS the video as well and see what they say.

    Btw I finally got my speaker situation figured out. I ended up going with 2 Celestion Vintage 30’s and 2 Celestion G12H-75 Creambacks in a X pattern. These speakers with the Archon are amazing, love the sound - super happy. These Celestion speakers went in flawlessly compared to the Eminence which I had to fight to get the mounting screws to line up correctly. Once I was finished I couldn’t believe how easy and quick it was compared to the Eminence speakers.

    Hope your doing great and thanks for the help :)
     
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  5. Lyric

    Lyric New Member

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    Thanks Bodia, did you just continue running those tubes? Any issues or anything? My main concern was mainly the one tube being 26 compared to the highest being around 32.8 or so.
     
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  6. Lyric

    Lyric New Member

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    So a small little update. I just played on the new tubes for about 30 minutes or so just seeing what occurs and here’s what I’m reading.

    27.15 - top seems a little more dim
    30.03
    29.55
    32.71

    I’m thinking of Tube Depot will send me another for the 27.15 one that I should be good. Only worry I have like it is is wearing out the other tubes because one is running a little under compared to the others so the others work harder. All tubes on their labels and boxes were written 26 except for the one which was written as 25. Probably that right there is probably it. I’ll update tomorrow.

    Otherwise I will say the Tung-Sol 7581a tubes sound a lot better. Some people claim tone is all in preamp tubes mostly but I seriously can tell a difference shockingly and maybe that’s cause these run at 35 watts vs 30 watt 6L6. I like these much better than the stock Ruby 6L6GCMSTR. I would say if you enjoyed the Archon as is you might just love it more with these tubes.

    Plus after playing for a bit and enjoying the Tung-Sol 7581a’s, I next popped in the new balanced/low noise/low microphonics Sovtek 12ax7lps in the Phase Inverter and placing a balanced/low noise/low microphonics Tung-Sol 12ax7 in V1. I previously had a Tung-Sol 12ax7 in the V1 slot but it was not balanced/low noise/low microphonics.

    - But here is the big one for anyone with one of these amps and this is actually the most stunning part of it all. Placing that Sovtek 12ax7lps in the Phase Inverter made this amp quiet as a mouse, silent. From the first day this amp always have a small annoyance in sound but sometimes you’d forget it after playing 10 minutes. It wasn’t like omg loud but the hum was a little excessive to most amps I’ve played but again nothing to make you hate it. I had even tried swapping a couple of the factory JJ 12ax7’s around with the phase inverter one and nothing changed. But now I’m like WOW, it’s like I woke up the beast in this amp. I don’t mean to be rude here but I don’t know why they “PRS” stuck that JJ 12ax7 in the phase inverter or V1 because there is much better out there. So new power tubes, phase inverter tube and V1 tube and this thing sounds better than factory that came with the Ruby’s and JJ’s. I know some say they have tube rolled these and never noticed a change but maybe it’s in that Sovtek 12ax7lps and Tung-Sol 7581a’s that made that change. I think the balance/low noise/low microphonics helped also too for the phase inverter and V1. And maybe those who didn’t notice much difference are tube rolling similar tubes to the factory ones. Heck I don’t know and I went into this thinking I wouldn’t hear a difference at all because of what I read on some posts but I certainly was shocked big time. I think now I know what tubes I will buy from now on and the amp sounds exactly how I want. I just gotta get that one power tube figured out.
     
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  7. bodia

    bodia Authorities said.....best leave it.....unsolved

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    I did. I set them as close as possible so the average between them was 30. No issues. I don’t have the amp any longer, but the guy I sold it to has had no problems.
     
    Lyric likes this.
  8. elvis

    elvis Hamfisted String Banger

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    The tubes will drift over time anyway. Not a Swiss watch by any means.

    I also dig the LPS for the PI. Good tube.
     
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  9. Tony Hayek

    Tony Hayek Musicianship is Dead

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    I like your Revstar
     
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  10. Lyric

    Lyric New Member

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    Thank you,

    it’s a really solid guitar and I love it. One of my favorites I’ve ever purchased. Anyone looking in the Gibson Les Paul/SG market it’s definitely worth looking at.

    It’s a 2018 Yamaha Revstar RS820CR
     
  11. DreamTheaterRules

    DreamTheaterRules New and improved member

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    I’ve read a few really great reviews of that guitar at TGP
     
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  12. Tony Hayek

    Tony Hayek Musicianship is Dead

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    I just got mine with p90’s and it’s outstanding, what a hidden gem. In fact, the pups sound better than my PRS.
     
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  13. Lyric

    Lyric New Member

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    P90’s sweet ;) I have a Reverend with P90’s and absolutely love it.

    When buying the Yamaha Revstar 820CR I looked an awful lot at the P90 version and came very close to it. I still believe I’ll grab one one day soon.

    I’m not surprised you liking the pickups better. I’ve read and seen nothing but great about PRS guitars and the Yamaha Revstar guitars too. Some say that some PRS guitars are kind flat sounding at times, I don’t know this for myself as I haven’t spent time on PRS guitars much but would like to buy one one day. But the Yamaha Revstar guitars like yours or the one I have get nothing but top reviews for sound, feel and quality. Once you hold one and play it, you know it’s a perfect guitar. Yamaha doesn’t skimp and always made great instruments.
     
  14. Tony Hayek

    Tony Hayek Musicianship is Dead

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    Absolutely I’m a bit disappointed with my PRS, not for the quality, it is kind of dark and flat sounding, the Revstar has more character.
     
    Lyric likes this.
  15. Lyric

    Lyric New Member

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    Yep, that’s exactly what I’ve heard a lot. I don’t know if that’s all PRS guitars but I hear it from time to time a bit often. But yes the Revstar’s are amazing, I couldn’t agree more.
     

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