Why does my Fisher sound kind of lean vs. my Rega Brio-R?

Discussion in 'Audio Hardware' started by action pact, Apr 15, 2019.

  1. action pact

    action pact Music Omnivore Thread Starter

    I have a '59 Fisher X-100 that was restored a few years ago. The tubes are:
    • '58 long black plate RCA 12AX7's
    • Reflektor (USSR) EL84's
    • GE phase inverters
    • Mullard Blackburn rectifier

    Since upgrading my speakers to Spendor SP3/1R2's, I've been less than thrilled with the Fisher. I don't think that efficiency is the issue - the Spendors are 88dB efficient @ 8 ohms, and there is no indication that the Fisher is working overtime (the volume is normally set around 9 or 10 o'clock).

    Conventional wisdom says that vintage tube amps typically have a lush, fulsome character, and yet my Rega Brio-R when paired with the Spendors has a fuller midband, more bass, and a less strident top-end. The Fisher has less weight and is tonally unbalanced vs. the Rega. (All of the tone knobs on the Fisher are set to 12 o'clock, ie: flat.)

    I have experimented with driving the Spendors off the Fisher's 4 ohm taps, and that sounded really awful - dull and slow.

    So what's going on here? Is this simply a synergy mismatch or is this indicative of the Fisher needing some attention? Or are the Spendors just revealing the limitations of the Fisher?
     
  2. Helom

    Helom Forum Resident

    Location:
    U.S.
    Have you replaced the power tubes recently?

    Have you tried switching polarity?
     
  3. action pact

    action pact Music Omnivore Thread Starter

    No! And EL84's are cheap enough that it wouldn't hurt to start there...

    It also occurred to me that they could just need re-biasing, which I've never done before, but doesn't seem that hard to do.

    There is no polarity switch on the amp, and it has been upgraded with a 3-pronged power cable.
     
  4. action pact

    action pact Music Omnivore Thread Starter

    Hmm, I've doing some research, and read that EL84's typically last 500 hours. Assuming that I use the amp one hour per day (a very conservative number), that's way less than two years; I've had this amp for maybe four years!
     
    jupiterboy likes this.
  5. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Looks like your speakers have their low impedance (6 Ohm) around 200 Hz, so maybe the amp can't really handle the demands. The phase angles in that area are also pretty steep. I bet the Brio just has better driver control.

    Does the Fisher have a 4 Ohm tap? Yeah, I see it does. I'd try the 4 Ohm tap if you are not using it already.
     
  6. action pact

    action pact Music Omnivore Thread Starter

    Yup, I tried the 4-ohm tap, and it sounded very dull.
     
  7. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    I hear you. I used to have some Vandersteens that were 6 Ohm and I moved them from 4 to 8 many times over the 20 years I owned them. Eight was punchier, and I think most people would have chosen that in an A/B comparison, however the 4 Ohm taps gave a really deep and rich soundstage. I always had to turn the volume up more touset 4 Ohm, but the result was much better. That amp was a hybrid with a SS output for the lower frequencies and EL34s for the mids/highs, so my experience probably won't transfer.
     
  8. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    Use good non-Russian NOS EL84 tubes and you'll be rewarded.

    I'm wondering if there is a way to bias the power tubes in the Fischer. Assuming there is, it possibly could've been biased on the cold side.

    Also, the rate at which tubes get used up is impossible to determine. If you have 2 NOS-measuring power tubes and run them 24/7 for 200h and measure them again, one possibly could measure far less than the other one. It's a crapshoot.
     
    action pact likes this.
  9. action pact

    action pact Music Omnivore Thread Starter

    [​IMG]
     
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  10. action pact

    action pact Music Omnivore Thread Starter

    That was my experience with both the KEF LS50 and Wharfedale Denton 80 as well. They liked the 4 ohm taps much better.
     
  11. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    All power tubes drift over time. Besides yours being old, you'd probably do well to check them at least every 6 months.
     
    action pact likes this.
  12. action pact

    action pact Music Omnivore Thread Starter

    So, here's what I'm thinking of doing, in order...

    1.) check the bias and adjust as needed.

    If that doesn't make a significant difference:

    2.) buy a quad of matched NOS Russian tubes and see how those work out.

    Then, if that sounds good...

    3.) Buy GE's or something more well-respected.
     
    Dennis0675 likes this.
  13. action pact

    action pact Music Omnivore Thread Starter

    So you agree that my 4+ year old tubes are possibly getting long in the tooth?
     
    Last edited: Apr 15, 2019
  14. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    Be careful about adjusting the bias. It shouldn't be done liberally as they need to be measured. There's a safe range and beyond that, I wouldn't attempt it. If you don't possess the proper measuring equipment and the tubes are biased too hot,... let's just say you wouldn't be happy with the outcome. :D

    I wouldn't suggest any NOS Russian tubes. With very few exceptions, they sound like the junk they are.

    If you're after weight and slam, get some NOS Amperex. But it'll cost ya... :(
     
    action pact likes this.
  15. action pact

    action pact Music Omnivore Thread Starter

    I think I can handle this...

    [​IMG]
     
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  16. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    I use mine a bunch and will usually put a new set in every year. I've always noted a pretty dramatic difference.

    My old amp didn't have a fancy biasing system that was user friendly. I had to first adjust the voltage for each channel. Then I would adjust each tube. I had to open the thing us and used a specialized clip with a tiny hoop that would link over the connecting wires on the tube pin socket then resistor. You'd adjust one, but the the adjustment would throw the other tube in that channel off just a little. It was a back and forth and one false move and you could kill yourself of the amp. I'm pretty happy I don't have to do that anymore.

    FWIW, the Fisher bias seems very basic and you use the chasis ground.

    Fisher | Audio Manuals Page 3
     
    action pact likes this.
  17. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    Good. Now, keep in mind that is the optimal reading the manufacturer chose. You can bias hot, meaning over the 44 volts shown here. That will give you a warmer thicker sound but also less headroom. How much you can overbias is dependent on the transformers' ability to cope. Guitar techs do it all the time on guitar amps.

    I wouldn't suggest you bias more than 10% but feel free to try it and see if you like the change.
     
    action pact likes this.
  18. action pact

    action pact Music Omnivore Thread Starter

    OK, I just bought a quad of matched NOS quad of 1991 Reflektors for $16.50 from a Ukraine eBay'er. I liked the amp before with those tubes, so let's see if it will sound "right" again.
     
    timind likes this.
  19. thegage

    thegage Forum Currency Nerd

    I don’t think it’s speaker efficiency or tubes as much as it’s the quality and size of the output transformers. So, yeah the Spendors are showing the limitations of that vintage amp driving those particular modern speakers.

    John K
     
  20. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    I also remember reading that the Brio had a heft and power, making it a great buy for those into classic rock but maybe not so much for, say, Jazz. Something to consider...
     
    Ivand likes this.
  21. bhazen

    bhazen Fab Fourever

    Location:
    Newcastle, WA
    ... and the current Brio (no -R) is a really stonking amplifier. Jus' saying.
     
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  22. VinylSoul

    VinylSoul Forum Resident

    Location:
    Lake Erie
    Mullard EL84 if you want punchy sound and long life. Andy at Vintage Tube Services.
     
    Strat-Mangler likes this.
  23. by all means, let us know how it works out.
     
    action pact likes this.
  24. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Not necessarily. If they still sound good with your other speakers it is not necessarily the tubes.

    But as tubes age, they will get duller and sloppier in that bass.

    You have an amp that is going to sound "soft" and not have the control of a modern day tube amp that is more linear and has larger and better output transformer's.

    Plus, most modern speaker's are voiced to sound their best with modern SS amps, because that is what people use with them.

    Most of those English design speakers are designed to be forgiving, not "accurate" and then not to be overly dynamic in the first place.

    I only use my tube amps on my vintage Altec A7's and the Zu, Omen Definition's.

    With every other speaker I own or have owned, I drive them with SS amps. There is one exception, the vintage Wharfedale W60's, W70's and W90's, which sound good with either a tube or SS amp, but I do prefer to use a 22-Watt or better amp with them.

    I wouldn't use a lower powered tube amp with your Splendor's. I would use a SS amp, just the way you are now.

    I don't think that most speaker's will perform their best with tube amplification.

    Tube amps are better matched with high sensitivity speaker's like Klipsch or similar dynamic speaker's.

    While some of these speaker's also will sound good with powerful tube amps, I don't think that the expense and the bother is worthwhile.

    I have three powerful Rogue tube amps, M-150 monoblock's, a Cronus Magnum I and a KT88 based Stereo 90 and I don't see any point in using these amps on speakers which sound perfectly good with SS amplification.
     
    Last edited: Apr 15, 2019
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  25. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    Another good option.
     

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