Preamps. I'm skeptical or explain to me what I don't understand.

Discussion in 'Fred's Barcalounge' started by NJDevil, Oct 26, 2021.

  1. Synchro

    Synchro The artist formerly known as: Synchro Staff Member

    Jun 2, 2008
    Tucson
    Admin Post
    If the PI is unbalanced it will drive the power tubes unevenly and that can cause some interesting effects in the power stage. At the extreme, this could be unpleasant, but asymmetrical signal processing can sound pretty good at
    lower levels. The long lived Boss SD-1 Super Overdrive uses asymmetrical overdrive, and sounds very good.
     
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  2. NJDevil

    NJDevil Country Gent

    Age:
    48
    Jul 9, 2014
    Commack, NY
    You make good points but all of the demos I have heard accent the presence of the preamp with not just additional tonal dynamics but increased volume. I do not think I have seen a preamp demo where any attribute is not accompanied by a very noticeable increase in volume.

    I know that any pedal, preamp or effect pedal, that dials in the tonal effect also boosts the volume. My Vertex SSS is a dumble emulator, or as I like to say clean tone SRV in a box. It boosts the volume in accenting additional dynamics....same with my Blue Note by J. Rockett. The same can be said about both the Ventris (although it thickens the tone w/ just a slight boost in volume( and my Catalinbread RAH.

    The nice thing is I can enjoy the additional tonal dynamics on my Roland Blues Cube Artist with a built in attenuator. The tone I love that neighbors can probably hear houses away, never loses an ounce of tonal character when I dial it down to .5 W. This can still be really loud but the master volume is adjusted accordingly on the Roland.
     
  3. calebaaron666

    calebaaron666 Friend of Fred

    Aug 15, 2018
    Portland, Maine
    That’s really very very kind of you to say.
    It’s mostly just Filtertrons thru the mystery brain preamp into a blackface fender amp (or blackface fender-style amp) with the volume on the verge, the bass set low, and the treble set high. Fast tremolo and the reverb around 4.
    I also always have an echo going. I have it set with many repeats so it’s not just the typical one repeat slapback. I think that effect dirties things up in a good way. I don’t really like using distortion except when using Fuzz on occasion.

    In all honesty, Ivy’s tone from this live recording is what I chase. It’s as if the repeats knob and the echo volume on her delay was turned way up by mistake because her sound doesn’t normally sound like it’s set like this.
     
  4. Synchro

    Synchro The artist formerly known as: Synchro Staff Member

    Jun 2, 2008
    Tucson
    Admin Post
    I’m not sure of what to think about the flowery descriptions of power amp breakup. I have heard high quality pedals that are supposed to emulate power amp breakup, and I didn’t care for the sound. It can run the gamut from crunchy and pleasing, to jackhammer abrupt.

    I’ve heard amps that sound harsh and abrupt when they break up, and others that sound great. The sound a Deluxe Reverb makes at 4-5 strikes me as an example of airy and light overdrive. It would make sense that most of this is preamp overdrive. As you increase the gain, the sound takes on a different character and a truly cranked Deluxe Reverb can get pretty nasty. Surmising a bit, it makes sense that as you push harder, the power amp becomes saturated and breaks up.

    But that’s just one amp design. The Tremor doesn’t have a high gain preamp, and it overdrives subtly. Early stage overdrive is more warm a than the Deluxe Reverb circuit, Crank it way up and the power amp starts to break up, which is hard to describe. Mostly, I use it for Surf, so I don’t really run it saturated.

    But that’s just one more amp design. If you have never played a ‘59 Bassman RI, you should seek one out. They have a very complex natural breakup with oodles of harmonic overtones. It’s a completely different thing. IMO, the overdrive I’ve heard on the ‘59 Bassman sounds like preamp overdrive, but the architecture of the preamp is nothing like that on a Blackface Fender.

    They all differ, and there are many varieties. A Marshall Bluesbreaker, or a Marshall 1974 (18 Watt combo amp), or a Marshall 2021 (20 watt, small piggyback), or an Ac-15. Crank up a Vox AC-30 (after prenotifying the seismological community) and you hear something completely different.

    As to which amps have more preamp overdrive, as opposed to power amp overdrive, that would take some serious testing with a scope, and I’m not so sure that the results would be worth the effort involved. I’ve played all the amps listed above at fairly high volumes and have the impression that most of what you hear is preamp overdrive. The AC-30, IMHO, may have more power amp breakup, which I think is consistent with the crunchy sound of these amps at mid song. Crank ‘em higher and the preamp breaks up, and passes a somewhat compressed waveform to the power amp, so the nature of the sound changes.

    There is no last word, on this subject.
     
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  5. TV the Wired Turtle

    TV the Wired Turtle Gretschified

    Jul 25, 2009
    Sandy Eggo
    Also maybe look at a guitar and a preamp to amp source, in a different context.. instead of what does this preamp DO TO MY AMP...
    Look at it instead like; What does the preamp DO with the guitar pickups?
    Many of you record or have recorded in the studio or w your own DAW.. and one of the things engineers get caught up in, add nauseam ('cause its amazing) is Mic and Mic Preamp relationship before it hits
    the recording console's channel strip be it analog or digital.. Very famous mixes have resulted in iconic pairings in the studio that we hold as benchmarks.
    ( ex. U-47s so favored by George Martin into the REDD.47 for that band, the Bagels or Bengals I dont remember. I think the Guitarist was George Foreman)

    The dance between a given Mic's character and the color and gain of a Mic preamp, is really important as the Mic Preamp is letting the Mic "hear" its
    subject in a particular way. Male, female human or guitar amp, drum head, woodwind, brass, etc. See where I'm going? So even if you have the corkiest of sniffer, scatter wound, semi wax potted, with cunife magnet, or alnico II, IV, V mags and grey fiber bobbin PICKUPS aka MICS (old school name for them)... simply turning up the amplifier yields ONCE response all the time.. while different preamps for those pickups changes the ballgame. Dynamics, texture, eq all interplay w those pickups on that guitar and vary the instruments response before it hits the amp source be it tube amp, solid state amp, soundboard.

    so much fun, so much variety and opportunity for a new muse
     
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  6. swivel

    swivel Country Gent

    May 13, 2018
    PNW
    "...presence of the preamp with not just additional tonal dynamics but increased volume?"

    I guess what you are saying is the presence of any pre amp results in more volume.... if the power amp setting is left the same for the comparison? Yeah, I get that. It boosts the input.
    Why wouldn't turning the pre amp down and amp up illustrate that the Volume is actually adjustable, implying you CAN change it? It's kinda like a Master Volume and a Channel Volume pot on an amp. The amp sounds different with the MV cranked than with it turned low and the Channel Volume cranked....
    You can do the same thing with a Pre Amp Pedal. Crank the pedal and turn the amp very low will sound different than the amp Cranked and the pedal very low.
     
  7. oneforsorrow

    oneforsorrow Synchromatic

    783
    May 15, 2020
    Iowa
    But what does a bagel cooked on an indoor/electric grill taste like? And does the cream cheese running into the grease trap act as a hi-pass filter or more of a tilt eq? Personally, I prefer lox to be pre-gain but post impedance adjustment to compensate for ... ok, I'll stop.
     
  8. TV the Wired Turtle

    TV the Wired Turtle Gretschified

    Jul 25, 2009
    Sandy Eggo
    what do you think of this?

      • Volume is how loud the OUTPUT of the channel or amp is. It controls loudness, not tone.
      • Gain is how loud the INPUT of the channel or amp is. It controls tone, not loudness.

    The difference between Gain, and Volume, must be understood that they are different from each other.

    Basically, volume is how loud something is after it’s been processed.

    So really, volume = loudness. It’s the loudness you hear.
    Here’s the important thing: The volume does not change the tone of the sound. It just makes it louder.

    Gain is the decibel (dB) input of a system.

    the gain controls how loud something is before it goes through any processing. It’s the volume level being sent into your plugins, preamps, and amplifiers.
    This is an important distinction. How loud something is AFTER processing doesn’t change the tone of the sound.
    But how loud something is BEFORE processing definitely will.
    Back in the analog days, gain was used in two ways:


    There was the gain on the microphone preamp. This turned up the level of the mic, which would change how the analog tech in the recording console would affect it.


    There was also the gain on a guitar amp, which turn up the level of the guitar. Most guitars had both a gain knob and a volume knob, meaning that you could send a ton of gain into the amp, overload it, then keep the volume reasonably quiet with the volume knob.


    That’s how guitar distortion was created. Overloading the guitar amp with gain so that the speaker can’t process the guitar cleanly.


    *Also regarding power amps power amplifiers usually have fixed gain, about 20x, or 26 dB. They need this to translate the input voltages (often around 1-2 V) to the speaker voltages. They may have adjustment pots in the input, but the gain of the circuit itself is fixed.
     
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  9. markeebee

    markeebee Country Gent

    Sorry, I don't want to be all sniffy, but that's just incorrect.

    Gain is the factor by which power or voltage is increased in an amplifier or other electronic device. Its a relative measurement, you can't have a signal of a particular gain in and of itself.
     
  10. NJDevil

    NJDevil Country Gent

    Age:
    48
    Jul 9, 2014
    Commack, NY
    You misunderstood me in that I did not make that statement object to fact as a constant to the way a preamp works. Rather my statement simply was that upon the demos I have seen, the engagement of the demoed preamp raised tonal dynamic and volume.

    Yes I get the fact the preamp, like many pedals, have a volume knob. We plug our guitars into our amp...really our preamp and we can control volume there also.

    So no. I did not state "the presence of any pre amp results in more volume" as if a universal delivery of all preamps from the very nature of how they are used is an automatic increase in volume. So what I was implying was that the greater volume witnessed in the demoes will bring whatever presence the preamp pedal brings to the mix will automatically "boost all the goodness you need and that is why you need a preamp." Whether by design or not, increased volume is innuendo for better performance/expanded dynamic/goodness of heaven, blah,blah, etc, etc..... The increased volume is just a variable I notice in many 'tube demonstrations.....including the recent preamp one from That Pedal Show.

    So by innuendo, the greater volume heard expands the dynamic and therefore the listener thinks the secret sauce of the preamp-in-pedal universe is the pure magic one must have because it can only be delivered this way. This lends to people being sold something vs. buying out of pre-defined specified requirement/design/wish.

    This is why I included "skeptical" in the title of the thread because I'm not ready to "drink the kool-aid" that is spooned out. The power of persuasion is always there.
     
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  11. NJDevil

    NJDevil Country Gent

    Age:
    48
    Jul 9, 2014
    Commack, NY
    That is how I understand it also.

    This is how I see it from a resource I read a while back I think is applicable here.

    A boost pedal is really just an amplifier with a single volume control and an on/off switch. The job of an amplifier is to take a low power signal and increase it’s power level. In the case of our boost pedal, it takes the low level output from a guitar pick up and increases it before passing on to the next part of the signal chain. The number of times the amplifier can increase the output power over the input power is referred to as the gain. A gain of two means the amp should output twice the input signal, and so on.

    Boost pedals normally list the amount of boost in dB, so how does that relate to amplifier gain? Let’s take a common boost pedal value of 15dB. To convert that to gain in voltage we use the formula:

    Vr= antilog(db/20)

    Where Vr is the voltage ratio and db is the increase in dB.

    Converting +15dB gain to voltage gives us 5.623413, or about a 5.5 times increase if we round it. So with our boost pedal, a 1V input signal would be increased up to about 5.5V.
     
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  12. swivel

    swivel Country Gent

    May 13, 2018
    PNW
    • "Volume is how loud the OUTPUT of the channel or amp is. It controls loudness, not tone.
    • Gain is how loud the INPUT of the channel or amp is. It controls tone, not loudness."

    • I think in the real world, layman's terms, that's not a bad description.
    • Although I disagree a little with "It controls loudness, not tone." We all know the tone of an amp or guitar changes when you turn it up or down. Even when there is no "Gain" control in the circuit.
    PS: There may be a technical description for a Pre Amp. I'm not using that if there is, I'm just considering anything in front of the power amp as part of the preamp. Why? Because a preamp could, I suppose, just have a volume control, no tone control, no notch filters, nothing else. Or it can have all kinds of things including what is in some pedals built in.​
     
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  13. NJDevil

    NJDevil Country Gent

    Age:
    48
    Jul 9, 2014
    Commack, NY
    I thought this video addressed your comment spot on around 1:40 and then expanded into some cool content.....also just sharing because I like the guy from JHS.

     
  14. oneforsorrow

    oneforsorrow Synchromatic

    783
    May 15, 2020
    Iowa
    This has always been one of my concerns with demo's. No matter how hard I try to objectively listen knowing that the volume change is like the flashing lights of a casino beckoning me in to help me part with my money, it's just too hard to tell what is volume and what is "pixie dust". The crazy thing is that the overwhelming majority of these videos are produced by folks who have the means to level match accurately by way of metering on their recording rigs. Yet, nary a one does. And to soapbox on the theme, one "influencer" who I actually get some good info from also tends to switch pickups right before he steps on the pedal. So whatever tonal reference point was just established has been thrown out the window at the same time the pedal is engaged.
     
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  15. oneforsorrow

    oneforsorrow Synchromatic

    783
    May 15, 2020
    Iowa
    I think this a great way to understand it. I would possibly note that while volume does not change tone, it may change perceived tone in that the Fletcher Munson curve illustrates our ears hearing frequencies more linear around 85 db. So, if an amp is turned up or turned down from that point, the perceived frequencies change.
     
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  16. NowEarThis

    NowEarThis Gretschie

    Age:
    70
    231
    Jun 23, 2021
    Northern Rivers NSW Australia
    Pre-(before)Amp = Amp feeding another Amp.

    Nett result, gain of first (pre-)amp times gain of second (and subsequent amps) = total gain. Eventually, one stage is going to overload, clip, distort or overdrive and so will subsequent stages, each adding harmonic content to the original signal relative to the amount of gain dialled in.
     
  17. gtrs

    gtrs Electromatic

    11
    Nov 29, 2020
    USA
    I've had and still own quite a few Kingsley offerings. At one point I was using a Maiden BF in front of the Minstrel (V2) and it wasn't night and day with/without the Maiden pushing the front end. BUT it was a fuller response across the spectrum if that makes any sense at all. The Minstrel (and his other pedals similar to it) is very amp-like. The Maiden made it more so. Also, I can lift the tone stack on the clean channel of my Bogner Shiva and the Maiden could give me a really nice BF clean tone.
    Fun stuff!
     
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  18. stevo

    stevo Friend of Fred

    May 1, 2012
    Atlanta
    The question becomes how out of balance are they? I'm not sure I've ever seen my PIs so far out of balance that it made a difference. And if there is that much difference that you can hear it, I would think you're about to loose a triode?
     
  19. gretsch-to-go

    gretsch-to-go Gretschie

    192
    Oct 2, 2019
    Palm Coast, FL
    I see the pedal as getting to the preamp of a more expensive amp in a magic box. Does one have the time to try to emulate an amp thru trial & error, do you trust your ears to do that ? If they can do it for under $ 50, the pedal is a instant solution to get the range of the amp you're trying to sim. I have a Behringer V-Amp 3 that has quite a collection of amp sims on it. I found it preowned for $ 40 and drive to go get it that was a couple of counties away. I think it was quite worth the investment, put that into any solid state practice amp and it makes an incredible difference. I bought it to enhance a sub $ 100 Pyle PVAMP60 R. It most likely would transform a Frontman 10g/15g into anything you would ever want in a tube amp really.
     
  20. petecarlton

    petecarlton Electromatic

    25
    Feb 10, 2021
    Nottingham, UK
    What a brilliant idea!
     
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