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preamp - tubes overrated ??

Discussion in 'Amps and Cabs [BG]' started by ingmar, Nov 6, 2002.


  1. ingmar

    ingmar

    Oct 14, 2002
    Normandy, France
    Just wondering:

    Out of couriosity, I bypassed the preamp section on my SWR Bass350 and used a Focusrite Tone Factory Platinum (mic/line/inst preamp with compressor, 2 sets of EQ, gate) to preamp my bass.

    I went back and forth between the SWR preamp input and the Focusrite, listening through my EBS 410 cab.

    The subjective result seems like this: the SWR 12AX7 preamp enhances the mid frequencies and reduces dynamics a bit. With the Focusrite, I can fairly welll imitate the tube preamp tone with proper EQ, excellent for defined finger style. When going to slap EQ however, the SWR pream is boring compared to the Focusrite only setup which delivers a very present and much more dynamic tone.

    Is this just me or are tubes overrated
     
  2. ingmar

    ingmar

    Oct 14, 2002
    Normandy, France
    Can you be more explicit Chris?:D
     
  3. I can't really tell how any equipment effects my playing until I try it on the job. It really comes down to how you sound to yourself while you are playing with other instruments. If a piece of equipment makes your bass sound better to YOU then it is worth it. A/B comparisons don't really mean much unless they can be done on the job with drums, guitar, monitors, keyboards, and a few loud drunks in the back ground. jmho:D
     
  4. ingmar

    ingmar

    Oct 14, 2002
    Normandy, France
    I know that A/B-ing by myself is not ideal, but I am pretty sure the mosfet sound is more useable than the tube. As a former sound engineer, I would definitely prefer the Focusrite tone.

    Couldn't it be that we're all so used to tube amps that mosfets were completely forgotten?
     
  5. Yeah, I was just kidding around. Just don't rule out tubes in general due to one experience. SWR ain't my thing, so I would never say what it was putting out portrayed tubes in the best light.

    Anyway, some folks dig the tube sound, some can't stand it. If you've got to have a tweeter in your bass cab, you probably won't dig the tube sound at it fullest. A lot of folks dig the full range modern clickety-plink-plink that solid state gives them. Tubes are more of a boom-boom-bawow kind of sound most of the time. That's a bad generalization, but my point is, to each his own. You just may not like the tube sound. No biggie. Just try out a bunch of different gear, and set the EQ and boosts and cuts for flat, then go from there. Every time I try an amp out in a Guitar Center or somesuch, the dang EQ is so whacked out it has no life to the sound. Try running flat and then gradually make some small adjustments to see what you get, with tubes and solid state.

    Chris
     
  6. Different Preamp Tubes have different tone characteristics. Try different tubes.
    SWR's preamp voice is preamp tube dependent.
     
  7. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Different tube circuits can give you different characteristics, usually even more so than different tubes will. The mere presence of a tube in a preamp might allow it to be marketed as a tube preamp but does not guarantee what most call the "tube sound."
     
  8. VicDamone

    VicDamone

    Jun 25, 2000
    Sounds like your comparing apples to oranges. even without a tube in the mix these two components are going to sound different. You might try a comparison with an Avalon tubed preamp before you pass judgement on vacume tubes alltogether. As I learn more about amp/preamp designs, the ability or quality of output seems to have more to do with the design, quality of parts, capacitance, power supplies, and the VAC quality, than tubes or solid state.

    As an ageing bassist I've lived with vacume tubes for many years and to be honest, I am so done with them. Their tone can be duplicated and even bettered (except for overdriving/soft clipping) by some modern solid state designs. From the day you install a new valve it's sonic virtues begin to degenerate. There're also somewhat limited at the frequency extrems.

    That said I'm still hunting for another creampuff SVT. We're on the brink of digital amplification, and shunt attenuation in pro audio. This will be a large step foward in the clarity of tone and timbre in the lower frequencies as well as the entire band.
     
  9. What does the tube pre-amp circuit do different than say a solid state pre-amp circuit? Can one sound like the other?
     
  10. ingmar

    ingmar

    Oct 14, 2002
    Normandy, France
    " With the Focusrite, I can fairly well imitate the tube preamp tone with proper EQ"...

    is this what you mean or are you talking about particular preamp design when you say this?
     
  11. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    There's no the tube preamp circuit; there are many, many different ways to implement tubes, transistors, or both into preamp circuitry.

    You can design a circuit to be very linear, to be very non-linear, somewhere in between. It's easier to make tube preamp circuitry linear and sound like solid state than to make solid state circuitry non-linear to have a "classic" tube sound, but the latter is not impossible.
     
  12. Bob I love it when you post cause it gives me chance pick your brain a little. What non-linearaties (is that a word) does a classic tube sound usually have?
     
  13. VicDamone

    VicDamone

    Jun 25, 2000
    Well, yes and no. Yes, because your able to get the same tone with the Focusrite. No, because it is possible to design an amp or preamp to have a signature sound or a warm tube like sound (with the exception of a tube amplifiers soft clipping characteristic) wheather its solid state or tubed.

    Sounds like you've stumbled into the world of microphone/studio preamps.
     
  14. jokerjkny

    jokerjkny

    Jan 19, 2002
    NY / NJ / PA
    Just plug into a Demeter VTBP-201s, or Kern IP777, or an Aguilar DB680, and you come back and tell us, k? hehe... ;)

    but seriously, these great preamps, which are a bit of a cut above the rest, do amazing things in bass rigs and really do its best to milk the tone of those 12AX7 tubes, and utilize them in the best fashion for those rigs.

    with my VTBP, i can hear a palpable difference from the stock pair of EH 12AX7's (thin, buzzy), to my current Tungsram ECC83 / Jan Philips 12AX7 combo (creamy, yet steely low end, and singing highs).
     
  15. What and how you play the instrument is a combination of the way your bass feels and responds and the way your amp/speaker/whatever sounds to you when you do your thing. Some people want tubes and only tubes in their amp. What they play just doesn't sound right to them unless it is coming all through tubes. I have never played through a tube amp that sounded like a SS nor have I ever played through a SS that sounded like a tube amp. To my ears when you add a tube to a pre-amp with a SS power section, the sound picks up TUBEishness but it still lacks that "Spongy smoothness" that tubes empart. I have a Alembic F1-X and I also have a Line6 Pod pro. that I play through a SS power-amp. To be honest the dif between the Line6 set to "tube pre-amp and no cab" and the F1-X is small. Played alone, the F1-X is a bit cleaner but they feel the same. But there will be others who hear something entirely different. That is because what you hear is the interaction of playing and listening at the same time.
     
  16. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    If you plot an X-Y graph of output voltage (on the X axis) versus input voltage (on the Y) of a circuit, you'd be plotting its transfer function. If the circuit is linear, the line you plot would be straight, at least up until you reach the clipping points. If the circuit is non-linear, it won't be a straight line. That means the circuit's gain changes as the input signal's instantaneous value does. Often in single-ended circuits with little negative feedback, the transfer function has a curve to it; perhaps the positive signal peaks might get squashed while the negatives get elongated. This is distortion, although it would probably sound pretty nice because it is asymmetric about the zero-volt axis--that is, the negative and positive voltages aren't treated equally--which produces even-order harmonics.

    Tube circuits are often purposely designed this way. Transistor circuits can be, too; in fact, I remember when we first started building single-transistor common-emitter circuits in one of my EE 10-something labs, I was playing with the resistor values to change the gain and the bias, and I found that with outrageously high gain and the right quiescent point, my 1 kHz sine wave started looking increasingly like an epicycloid. ;)

    Here's an article that does a decent job of illustrating tube non-linearity: http://www.tubecad.com/articles_2001/Inv_Dist_Cancellation/index.html

    There are probably better articles out there, but I just did a quick search.
     
  17. Bob! You are the man. I'm not worthy:D