tube vs solid state rectifiers

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by toneman335, Mar 1, 2008.

  1. toneman335

    toneman335 Member

    Messages:
    527
    Joined:
    Dec 30, 2006
    Any tonal effect using solid state rectifers instead of tube? Guess I am wondering if tube rectifiers sound better.
     
  2. Free

    Free Member

    Messages:
    1,305
    Joined:
    Jun 18, 2005

    Absolutely! It's one of the most crucial aspects of any amplifier's tonal response. You get varying degrees of voltages and sag to the output section with each type of tube rectifier. Solid-state rectifiers give out the most voltage of any rectifier - about 20v more on average than a GZ34, which is the highest voltage tube rectifier. The higher the voltage to the output section, the more volume/wattage, bass-response, attack, headroom and punch an amp usually produces. One same amp, with the only difference being whether you use a 5Y3 or solid-state rectifier, would produce around 14 watts (5Y3) or 20 watts (SS) RMS respectively.

    ***Just make sure your amp can handle the voltages that GZ34 or SS rectifiers produce before using one.***

    From lowest to highest voltage or most to least sag:

    5Y3 -> 5U4 -> 5V4 -> GZ34 -> SS Rectifier

    Not better at all - just DIFFERENT. Tube rectifiers don't sound any better than solid-state, just because they are tube. Tone difference come down to voltage and sag characteristics only. The rectifier stage is not even in the direct signal path, so a SS rectifier can still be run in a signal path that is considered "all-tube". Each rectifier type has it's own virtue in a given amp design. Some amps could use less voltage at the rectifier, some could use more. If you already have a saggy Class A design, for example, a GZ34 or solid-state rectifier works wonders for getting more punch, bass, attack and volume. If you want sag city with more warmth and less attack that distorts fat on vol 4, use a 5Y3 up to a 5U4. Etc, etc...
     
  3. booj

    booj Member

    Messages:
    173
    Joined:
    Jan 18, 2008
    Marshall sound - S.S. rectifier
    Fender sound - tube rectifier
     
  4. Free

    Free Member

    Messages:
    1,305
    Joined:
    Jun 18, 2005
    It's a bit more complicated than that. A Fender will sound like a Fender with ANY rectifier, as will a Marshall. And, there are many tube-rectified Marshalls both vintage and boutique, which sound as every bit "Marshall" as a Super Lead.
     
  5. jh45gun

    jh45gun Member

    Messages:
    409
    Joined:
    Dec 29, 2006

    Not really there are lots of Fender amps that used SS rectification
     
  6. epluribus

    epluribus Member

    Messages:
    9,175
    Joined:
    Dec 14, 2005
    So how would you determine whether the PT can handle a "bigger" rectifier, like going from a 5Y3 to a GZ34? (Or in my case, a 6X4 to something bigger?)

    As for the rest of the amp, I can see what you mean about setting the circuit up to make use of the higher available voltage--lotsa things may change and need adjusting.

    Thx in advance.

    --Ray
     
  7. Free

    Free Member

    Messages:
    1,305
    Joined:
    Jun 18, 2005
    Hi, Ray. Exactly, sir - "lotsa things may change" indeed. The best route is to ask the tech who built your amp. If it's mass-produced, ask around in tech forums or try here in the a Amp Tech section of TGP. Good luck!

    -Mike
     
  8. slegros

    slegros Member

    Messages:
    499
    Joined:
    Sep 9, 2007
    Cesar Diaz SRVs late amp tech had this to say about tube rectifiers in an article he did for Tonequest:

    We never used tube rectifiers. We always
    replaced them, and I don’t recall a single amp that he used
    that had the original tube rectifier. What happens with tube
    rectifier is, not only does it get hot, but it’s right there is front
    of the power transformer, and it’s really susceptible to power
    supply spikes. When that happens, the tube will see it immediately.
    It’s a common complaint – “I turn on my amp and it
    sounds fine but by the end of the set it’s sounding really distorted.”
    That’s the rectifier, because they are just really inconsistent.
     
  9. epluribus

    epluribus Member

    Messages:
    9,175
    Joined:
    Dec 14, 2005
    Hi Mike.

    That would be me. :)

    No kit, no plans--scratch-built 2x12AX7, 1xEL84, tone stack, various inter-stage attenuation. Now in about the 87th iteration on the breadboard. Been to tweed, blackface, cathode-follower, cascading-gain, channel switching, etc...with varying degrees of success at building an oscillator along the way...:rolleyes:

    Yeah, it's out of a '66 Kalamazoo Model II. The OT is a Woodward-Schumacher, but I've found no data on the PT yet.

    Actually, I've spent considerable time learning to alter the entire voltage environment in the circuit, both as a whole and as isolated stages, to see what tone- and response-shaping tools were available. In the process I've been able to measure and observe the results vs. the theories outlined in several books and online resources. Most important, upon establishing in quantifiable terms the impact of such things, I have an advantage ya don't get from books--an audition. I'm learning to anticipate the impact of my circuits while still pencilling them in.

    But I've not yet fiddled with anything south of the rectifier. In the interest of saving $ on lots of transformers, I thought I'd get the rest of my theory nailed down before tinkering with expensive hunks of iron. This thread struck me as a good place to start thinking about matching rectifiers to power supplies.

    Nobody told me soldering smoke was habit-forming...

    --Ray

    No trem or verb...don't need the detours...yet. :)
     
  10. Tone_Terrific

    Tone_Terrific Member

    Messages:
    25,264
    Joined:
    Dec 26, 2004
    Location:
    Canada-GTA
    I was of the mindset that the rectifier and power supply were out of the signal circuit and their tonal effect was limited to the times where the PS was pushed hard enough to cause actual voltage variation due to current demand.

    And then, I saw an explanation of how the speaker is actually driven via the mains power through the power supply and the PS is really just modulated by the signal line to produce the current variations through the output transformer i.e. the classic 'valve' explanation. This viewpoint puts the rectifier right into the signal path and justifies all sorts of variation in tone due to PS design.

    I have NO clue about the relative merits of each theory but it does suggest a lot of investgation could be done. Somebody probably has done it. Links?
     
  11. Free

    Free Member

    Messages:
    1,305
    Joined:
    Jun 18, 2005
    Good for you, Ray, so you're the builder. Cool. Well, note that 6X4 rectifier general voltages are even lower than 5Y3 voltages, so I'll use that tube as an octal rectifier reference for the 6X4, as the 5Y3 is the lowest voltage common octal rectifier. As a general orientation, a 6X4 has about 75 volts less max capacity than a 5Y3. Additionally, a 6X4 has about double the voltage drop across it, so it produces considerably more sag. A 6X4 has only about half the current capacity of a 5Y3 too.

    All that said, YES, look into your rectifier situation if you want more beef and output before you go into the expense of transformers. You're going to have to do some research, buddy, as this project is beyond my knowledge. I know it involves different power supply (5 volt) from the transformer and other things, if you want to go up to octal rectifiers. If the stock transformer doesn't have a 5 volt supply, you'd have to replace it anyway, if you went with an octal rectifier.

    Instead, I would take a serious look at installing a solid-state rectifier - a lot easier and would turn that amp into a beast potentially. In my experience nothing beats the tone of a SS rectified cathode-bias amp. All the compression and sag one needs is in the cathode-bias circuit, so there's no need for rectifier sag. The SS rectifier brings in more punch, attack and headroom. Hope that helps.
     
  12. VikingAmps

    VikingAmps Member

    Messages:
    395
    Joined:
    Feb 21, 2007
    Location:
    VA
    A true class A amp doesn't have power supply sag, at least not until it's saturating. That's because the current being pulled from the power supply is the same from idle all the way up to the point of saturation. At that point it's very hard to tell the difference between power supply sag or the power tubes themselves saturating.
     
  13. Free

    Free Member

    Messages:
    1,305
    Joined:
    Jun 18, 2005
    Most play Class A amps to the point of saturation, which doesn't take more than about 12:00, and it's dropping voltage to the cathode resistor constantly. Though my comment is actually correct, as all Class A conduction designs are cathode-bias (I sometimes use those terms interchangeably), I meant to specify CATHODE-BIAS. That is where the sag comes from. There is no such voltage drop with fixed-bias - this is the distinction I made. There's no question that cathode-bias creates sag. It's a fact of electronics and a fact of TONE. All one needs to do is play any such amp to make this clear, even if solid-state rectified, as one of my cathode-biased amps is.
     

Share This Page