60 or 50HZ does it matter (Hogy)

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by abergdahl, Feb 8, 2004.


  1. abergdahl

    abergdahl Member

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    When buying an amp made for US current 120V 60Hz as step down transformer will make it usable with the 240v we have in Europe. But we also have 50hz, does it matter in any way what Hz an amp is designed for? Will amp made for 60hz sound different if fed with 50Hz? Also would an amp made in Europe (50hz) sound sound different in the US than it was designed to sound?

    Thankfull for help..
     
  2. John Phillips

    John Phillips Member

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    Not hogy, but my guess is that it does make a difference. I say 'guess', because I've never A/B'd it - you'd need an AC generator of some sort capable of running at either frequency... and I didn't play through any gear I was 100% familiar with when I was in Canada :).

    Certainly the PT will run slightly differently at the two frequencies. Whether it makes enough difference to be a concern I don't know.

    Do any of the power-conditioner type units or inverters that can run from a DC source have switchable output frequencies? I've never seen one...
     
  3. abergdahl

    abergdahl Member

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    Thanks John,

    Yes i thought that you would understand the issue, since you are a European. I have heard from some Swedish amp tech friend that MOST LIKELY its only hum thats affected.
    The Fire Amp has a 240V PT now would a 250V 50hz PT make the rest of the circuit work exactly as it would with a 120V 60hz PT?
    Looks like this area needs some research.
     
  4. hogy

    hogy Member

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    The power transformer will run more efficiently on 60 Hz. If the transformer is designed with mostly economic goals in mind, you'd want the smallest core possible. That's why the old Fender blackface amps used slightly bigger power transformers on the export models (with the red voltage selector in the back). They needed to make up for the loss of efficiency when run at 50 Hz., but didn't want to splurge and use the bigger transformer on the domestic amps.

    I can't speak for other manufacturers, but the Komet's power transformer is way overdesigned to begin with, so the efficiency issue really doesn't come into play.

    Check with your amp builder to see what he thinks. It won't affect hum, though, except the pitch of it.

    There is a way to convert 50Hz AC to 60Hz AC, I remember a Hammond player in Germany had something built because the tone generator of his B3 needed to run off 60Hz. I think it wasn't cheap, though, but if you need it, I can find out what he did.

    Hogy
     
  5. abergdahl

    abergdahl Member

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    So if i where to import an old BF Fender from the US the small transformer could be an issue.. The amp would be under powered, on the other hand i believe they where made for 110V and in the US you now have 120V which creates problems as well...

    Thanks Hogy, Im at least a bit wiser.
     
  6. reaiken

    reaiken Member

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    Hogy's right - a transformer core designed for 60Hz can overheat on 50Hz. Just as with an ouput transformer, the power transformer must have a larger core to work properly at a lower frequency (this is why aircraft power was always 400Hz - the transformer cores were smaller and weighed less).

    The amount of hum shouldn't change, just the frequency of the hum (for nitpickers, the filter circuit will allow a bit more ripple to get into the circuit because the choke/filter cap circuit has less attenuation at 50Hz than at 60Hz, but it is likely insignificant).

    Our PT's are designed for 50Hz/60Hz operation and all international voltages, and are rather large compared to most manufacturer's 60Hz only units.

    I wouldn't run a valuable vintage Fender on stepdown/50Hz for long periods of time without checking the power transformer temperature carefully.

    Randall Aiken
     
  7. SeanF

    SeanF Member

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    motor/generator? that's the simplest way I know, unless you wanna invest in a variable-speed AC drive.
     

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