Ampeg V4 Noise Floor

Discussion in 'Amps and Cabs [BG]' started by Slaplord88, Jun 28, 2022.

  1. No, it's 100% silent.

    3 vote(s)
  2. There's very, very little hiss or buzz, practically unnoticeable.

    5 vote(s)
  3. Yeah, it makes some audible noise, but it's an old tube amp and sounds great otherwise!

    1 vote(s)
  4. Loud consistent noise, only covered up by the two guitarists' Marshall stacks in my band.

    0 vote(s)
  5. Call me Buzz Aldrin this thing sounds like a Saturn V during takeoff

    0 vote(s)
  1. Slaplord88


    Jun 11, 2013
    For those with Ampeg V4's of all era's including the reissue:

    How quiet is the background noise of your amp when powered on?
    Patrice B likes this.
  2. Celen


    Aug 25, 2018
    Gothenburg, Sweden
    I have a new V4B, it does hum a little (regardless of volume and other settings). The hum is quieter than the cooling fan on my previous amp, though, so it doesn’t bug me too much.
    Buster Brown and Kevin Sullivan like this.
  3. coreyfyfe


    Nov 19, 2007
    boston, ma
    I have/have had a few older models, not a modern one, but they’re generally pretty quiet when running up to spec. I’ve had issues with one where the isolation washers on the speaker outs were missing which caused some induced hum, but other than that mostly just normal tube related issues if any.

    The catalogs for the old V4B and others are in the portaflex wiki, they say 80db signal to noise ratio.
    Sales Literature and Advertisements |

    The new amps say the same’s Manual - English .pdf
    Kevin Sullivan likes this.
  4. Jim C

    Jim C I believe in the trilogy; Fender, Stingray, + G&L Supporting Member

    Nov 29, 2008
    Bethesda, MD
    I had an older model with 7027A power tubes.
    Probably owned it 20+ years and it was super quiet.
    Sold it with the original tubes.
    Probably the best sounding bass amp I've ever owned but 100 watts was not enough clean headroom with a 2x15 cabinet.
    Al Rivera and Kevin Sullivan like this.
  5. beans-on-toast


    Aug 7, 2008
    Do you have one that hums or hisses?
    Kevin Sullivan likes this.
  6. LetItGrowTone

    LetItGrowTone Gold Supporting Member

    Apr 2, 2019
    Closely related to hum itself is the problem of the hum mixing with notes from the bass, especially low notes on the E string, to produce "sum and difference products" - beats. Sounds a little like tremolo. I suggest this as something to listen for (in the context of the thread) because I don't notice the hum, but do hear these beats. In my case it's worst on G, E string 3rd fret.
    I don't have a V4B but my SVT-CL does this a little. I have no idea whether or not this small amount is normal for this amp.
    Also closely related - if the V4B has the toroidal inductor for the mid control and I think it does - at least one (apparently technically advanced) member here replaced that toroid in an SVT-2 with a better one to reduce hum being picked up in the inductor (like an antenna). There was a service bulletin (I think that's what it's called) covering this for at least one model of Ampeg amp with that inductor. That's all I remember.
    Last edited: Jun 28, 2022
    Kevin Sullivan likes this.
  7. C2012 model V4B RI here.

    And as far as I recall, it's pretty much silent. I s'pose it's got a hum like they do. But I've not noticed it... that I recall
    Kevin Sullivan likes this.
  8. Slaplord88


    Jun 11, 2013
    Thanks for the replies. Mine has a bit of a background hiss. Nothing that would be even remotely audible when performing, but it's there. Was just with the tech for a tube socket tune-up and some cap replacements and I'm taking it back there today to diagnose. We're almost certain it's nothing more than a a bad preamp tube, but I wanted to check in with others and see what's considered acceptable
    beans-on-toast likes this.
  9. beans-on-toast


    Aug 7, 2008
    A tube is a possibility and a good place to start. Wire layout to the tone switches and pots should be looked at. Check the shielded wires inside the amp, if they were moved something may have broke. Pay close attention to the ext amp jack and wire. Unsoldering it on the PCB can be revealing.

    Your tech should be able to trace through the circuit to locate the source of the hiss. Could be a bad component or solder joint.

    If your speaker cab has a tweeter, it can reveal hiss that wouldn’t normally be heard.

    A common source of hum is the chassis input jack contacts, this is the main ground. Oxidation here can be a problem. Also, the two speaker out jacks require isolation washers.

    For the record, my ‘74 is very quiet.
    Kevin Sullivan and Jim C like this.
  10. JeezyMcNuggles

    JeezyMcNuggles Supporting Member

    Feb 23, 2018
    Santa Maria, CA
    I suck, but nobody really notices
    Mine's a couple years old. It's dead silent.
  11. My old V4 is noisy at idle but with @beans-on-toast and @Wasnex help, I have a couple of strategies to try in the following weeks.
  12. I have a 1974 V4 and the only time I get any noise is when the spring reverb is turned up (I leave it off 99.9% of the time). The bass-specific V4Bs don't have a reverb.
    Patrice B likes this.
  13. Slaplord88


    Jun 11, 2013
    Thanks for all the replies on this thread. Convinced me to not accept the slight hiss/static in my V4 that remained after a recent servicing. Took it back to the tech, and it turned out I just needed to replace two old preamp tubes (and I guess some coupling caps for good measure), it is now running silent and sounding great!
    Last edited: Jul 25, 2022