Does the rectifier tube really affect tone?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dzook, Jan 13, 2005.

  1. dzook

    dzook Guest

    Does the rectifier tube have a significant tube have a significant effect on tone? I'm not talking sag - I mean in the way that different preamp tubes affect tone. Does changing the rectifier change the change the amp significantly?
     
  2. BUDDADRIVE

    BUDDADRIVE Guest

    you talking changing for the same rect type? (Mullard GZ34 for an American 5AR4 - not subbing a GZ34 for a 5Y3 etc?) Assuming so....

    It is not supposed to, but I swear when I put a big bottle Philco, GE, whatever 5U4G in my Budda SD30, I can hear a "bigger" tube sound than a small bottle RCA 5U4GB.
     
  3. fullerplast

    fullerplast Senior Member

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    Why yes, of course they do.....:D ;)

    It's all here:

    rectifiers and tone
     
  4. dzook

    dzook Guest

    I was thinking of changing the same tube type for a different brand.

    Fullerplast - thanks for that link - I'll have to set aside a bunch of time to read through it.
     
  5. fullerplast

    fullerplast Senior Member

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    Welcome to the gear page, dzook.

    As you can see, you've jumped right into the deep end with your first question to the forum. It's just one of those "special topics"...:cool:
     
  6. dzook

    dzook Guest

    So I see - I guess I didn't know what I was getting into there.
     
  7. grantster

    grantster Member

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    I never used to think that there was much of a difference in rectifier tubes until my tech and I were voicing one of my deluxe reverbs. I would play for a while and then change to a different rectifier tube. I was amazed at the difference in tone. I did not think I would hear much of a difference.
     
  8. goneracin

    goneracin Member

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    I know in my personal experience, it can and does change the tone, and the feel of the amp. I have several times changed from 1 brand ez81 to another, and had the character and presence change, sometimes a subtle change, sometimes a much more noticible change, to the point my wife heard it in another room. This was with 2 tubes that tested fine, and the b+ voltage stayed pretty similar.
    Just my .02
    Bob
     
  9. Wakarusa

    Wakarusa Member

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    For those of you who hear a difference...

    Is the effect predictable by brand (like general differences between manufacturers), or is it pot luck (like differences between two tubes from the same manufacturer)?
     
  10. larrylover

    larrylover Member

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  11. Wakarusa

    Wakarusa Member

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    Been waitin' all day to drop that one, eh? ;)
     
  12. TheAmpNerd

    TheAmpNerd Member

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    Folks,

    It works like this. There really is only once tube
    and they ALL sound exactly alike.

    The come in different sizes and shapes just to make
    you think they are different.

    They come in different ratings and numbers,
    just to make you thinik t hey are different.

    The make amps look differenct just so you
    think they are.

    ALAS,

    Every "Fricking" one of these is exactly the same as
    every "Fricking: one of the other ones.

    The only difference is Y O U.

    That is right, only Y O U make the difference.
     
  13. larrylover

    larrylover Member

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    That's right. As Wakarusa and Ole Teleman know, they are all the same, it is just anyone with an ear can tell they sound different.
     
  14. TheAmpNerd

    TheAmpNerd Member

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    Todd,

    Yep is sure is. I have these old black plate square getter
    5751 from the 50s and every amp I plug them into
    brings out their MOJO.

    Same can be said for the hand selected Sperry branded
    RCA Black Plate 6V6s...Much more so then just the regular
    6v6s, these really are the ****!

    Then there is that Tong-Sol 5881 tube that just does
    it consistant majic in a tweed bassman.

    Same with the NOS Chinese MesaBoogie tubves, these
    have great hi gain tone and last forever...AND when you
    put a silver special in the hole slot, it makes these amps
    sing.


    Kinda like Caps too. Had an 70s FTdeluxe reverb in hfere
    that the the output tube sockets blew out.

    opened it up and sure nuff, the CC screen resister had
    flailmed and took ouit the realated sockets components.

    So I replaced the sockert with a ceramic one (I've got them in inventory....and rebuilt the rese with the wirewouind for the screen and a verticle mounted CC grid stopper. Same thing I do at the preamp sections, remove the resisor from the jack and place it riight atop the
    grid.

    Plug in and played, sounds good....

    ... next step, blackfaceidng it and getteing rid of the Fender blue caps and putting in some much better stuff.
    This will yield in more clarlity, touchrsponsisveness,
    harmonics, and expression fo the musician as artist.

    They love em!

    Hey whe I see these guys again, they tell me thei drummer loves their tone AND the studio engineer
    loves it too.

    Can't ask for more than that, other thank cash flow,
    right guys?
     
  15. Wakarusa

    Wakarusa Member

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    Not really the question I asked. Well aware of (and have my own personal opinions on) the different flavorings of preamp and power tubes.

    What gives me pause is the claim of mojo associated with rectifier tubes. In my personal experience I haven't found much tonal/dynamic difference from one manufacturer's rectifiers to another (though there are marked differences in durability and reliability), nor much difference from tube to tube in one manufacturer's line. Then again, I haven't listened very carefully to diffs from rectifiers either.

    So, there are enough people that claim they can hear a difference that the topic is worth investigating a bit further... hence the question: in your (everyone's) opinion, are there particular manufacturer's rectifiers that you find "sound" better, or is it more luck of the draw and kismet -- sometimes you just hit on a rectifier that's a little magical?

    If the feedback points to a particular brand, I can run some pretty exhaustive tests to try to figure out what real physical differences there might be.
     
  16. goneracin

    goneracin Member

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    Todd
    My guess is it has to do with the tubes internal resistance, and response time from when it sees a demand to when it recovers. How much it drops, its lag time untill recovery, speed of recovery etc. which will vary with parts tolerences just like any other tube or part. All I can say for certain is I can hear it, but it doesnt always follow brands. I have 1 old NOS mullard EZ81 that is my standby, its never going to be sold in an amp, just to use as a reference. I also have 1 old Sylvania that has sucked in every amp its been in, and it will never be sold either, as Im afraid of it sucking :D .
    I dont think the rectos change tone like say a preamp tube, but it does affect its character and feel, and for lack of a better term its "springyness" and bounce. ****, that made no sense :D
     
  17. Blue Strat

    Blue Strat Member

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    What Todd said, though I don't have tbe best ears (after 30+ years of gigging with DRUMMERS) and tend to adapt to whatever rig I'm playing. I also have great difficulty distinguishing between tubes that I'm hearing 1+ minutes apart.

    I'd say that the difference is subtle at best but many of my customers disagree...especially when it comes to replacing a "third world" 5AR4 with a NOS 5AR4. I would think that the "feel" could be different due to varying forward resistance resulting in different "sag" response. This can influence at what volume the "sweet spot" of an amp is which could make a huge difference in some situations.

    BTW, if in testing/comparing ANYTHING for tonal differences, if you're not doing a "blind test", one in which someone else is changing the variable and you have no idea which one is being used at a particular moment, your results are generally going to be BS.
     
    Last edited: Jan 20, 2017
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  18. fullerplast

    fullerplast Senior Member

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    After all the previous discussions, I think there are two components to consider.

    One is the instantaneous response to load, as mentioned, affecting the sag and feel of the amp. The amp's filtering also plays a part in this so certain amps may be more or less affected. This would be only be noticeable at high volume.

    The second component would be the difference in voltage drop between rectifiers affecting the bias current. A two percent difference in plate voltage (say 460 to 450V for example) could result in a change of almost 1ma of bias current. To the extent that someone can hear a difference between 35ma and 36ma of bias, that difference could be attributed to a rectifier change. This would be noticeable at any volume and may account for the difference some people hear at lower volumes. Again, the amp design would play a part as cathode biasing would be more immune to this effect, relative to fixed bias.

    That's my theory, FWIW, on the rectifier's possible impact on tone. IMHO, YMMV.
     
  19. Wakarusa

    Wakarusa Member

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    It's the dynamic internal resistance that I think might be interesting to explore. Keeping in mind that internal resistance (and therefore voltage drop and sag) is mapped as a curve I'm wondering how much variance there is in that curve (brand to brand, tube to tube) and whether or not you can predict the difference in amp dynamics based on that.
     
    eclecticsynergy likes this.
  20. larc

    larc Member

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    Categorizing general characteristics of tubes between different manufacturers is no easy task. I'm not sure there's a simple black and white answer. Some manufacturers change and tweak their designs...this fact alone complicates things. Depending on the era in which a particular tube was made, it's possible to find differences in tubes of the same designation. In other words, tubes coming from the same manufacturer could sound different depending on the period, date, revision, run, batch they are from. If it will help provide more insight, here's my observations pertaining to all the 5AR4/GZ34 rectifiers Ive experienced.

    Chinese 5AR4's (purchased in the late 80's early 90') provide a good amount of low end (bottom). They have thickness, punch and presence in the lower mids, but they lack highs and are noticeably darker than Sovteks. Sovteks that I purchased during the same period have extended highs, but lack bottom...they sound and feel thinner. Mullards on the other hand are the best of both worlds...neither bottom heavy or top heavy; more balanced sounding with good presence.

    In 2003, I acquired 2 new Sovteks and discovered they changed their tube. The new ones sound better compared to older versions. I detect more bottom (lows). They still have "highs" and seem better balanced...notes seem to have more presence and possibly more gain. Comparing their internal parts, I notice differences in the size of serrations on the plates...also notice different shaped spacers and getters. In one of my boutique amps, I prefer the performance I get using the new Sovtek over a Mullard.

    I have a bunch of Mullard GZ34's which bear the "F32" coding. Comparing their construction, I can separate them into 5 different styles (and they do sound different). To make things simplier (more general), I'll just basically divide them into 2 groups...those with 4 serrated edges on each side of the plate and those with 7 serrated edges... For the large part, I'd say those with 7 serrations tend to be brighter sounding than those with 4 serrations. Those with 4 serrations don't seem as bright, but feel smoother and thicker...possibly more lows and maybe creamier...it's all pretty vague (my Mullard comparisons happened several years ago using different amps). To make things more interesting...I have a hunch Sovteks might've been patterned after Mullards with 7 serrations. Their plates look similar and both tend to be brighter compared to Mullards with 4 serrations. Mullards with 4 serrations seem more like Chinese tubes.

    Sylvania (big bottles) Only have 3. Compared to my Mullards, these provide a bigger bottom (deeper lows). I don't recall for sure but I think the bottom seemed rounder and saggier. Over all this tube has a sweet round presence to it.

    JJ GZ34...I only have 1 and it came in my Sex Amp. Last year I replaced the JJ with a Mullard (7 serrations / silver flashing on the top and bottom of the glass envelope). Several of us were in the room and we all heard a drastic difference! It wasn't subtle...the impression I got was similar to comparing a good preamp tube with a crappy one. The JJ bumped up the presence in the mids vs. the Mullard sounded noticeably scooped. The JJ also seemed to add more gain or sustain...this observation could be due to the fact that I got much more harmonic complexity in the mids (notes just bloomed and sustained more). It occured to me that perhaps something was wrong with the Mullard. Yesterday I took the same exact tubes (Mullard and JJ) and put them in another boutique amp (even tried a Sovtek too), all 3 tubes performed fine and the difference was much more subtle compared to the Sex Amp. This experience really shows how some amps vary and respond differently to tubes...go figure.
     

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