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Walter Woods tech ?'s

Discussion in 'Amps and Cabs [BG]' started by Brad Maestas, Nov 23, 2005.


  1. Hey guys, maybe you can help me out here:

    1. Does anyone know the amount of current inrush there is with a Walter Woods Ultra? I can't measure it with a multi-meter, right? I don't know anyone close by that has the proper gear. I first became aware of inrush when I got a Stewart 2.1. It has tripped breakers dozens of times whenever I first plugged it in. My tech in KC told me that the 2.1's inrush regularly exceeded 15 amps. Unlike the Stewart that initially draws power when its' power cord first being connected to mains, the WW exhibits current inrush only after I engage the power switch. There seems to be no noticeable inrush when I first plug it in.

    2. Is it safe to run a WW without a speaker load connected to the outputs? Sometime I want to be able to use the WW just as a preamp. I searched and couldn't find anything specific. I would assume it would be okay but you never know. :)

    3. A related question: Should the amp be off when I'm inserting and removing speaker leads from the amp or the cabinets? I know Acoustic Image warns that their amps can be damaged if you short the connection, something apparently easy to do with a 1/4" when it's moving through a jack. I'm not sure if that's something I have to worry about with the WW. When I'm testing cabs it becomes a pain to have to power it up and down all the time plus I worry about that not being good for the amp, either. Thanks! :D

    -Brad
     
  2. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    1. No idea about the inrush.

    2. Yes, it is safe to run with no speaker connected, I'd turn down the master gain though.

    3. It is best to have ANY amp using 1/4" speaker jacks turned off when connecting speaker cables. This is a major advantage to Speakons and bananas, no way to short hot to ground.
     
  3. +1 What is 'inrush'? It sounds like it has something to do with a spike when you turn the unit on (people have mentioned blowing circuit breakers when turning on the DB750). If that's what you are talking about, this as absolutely not an issue with the WW. I've been using an Ultra for years and have yet to have any issue when turning the amp on or off.
     
  4. zombywoof5050

    zombywoof5050

    Dec 20, 2001
    Have you tried plugging the SW2.1 into a power strip (that is in the off position), and then turning on the power strip? Maybe that will help.

    If you 'must' unplug 1/4" speaker jacks from the amp while it is on, turn all the volumes down first and always unplug the cable from the amp first. Unplugging a 1/4" plug from the amp side first should avoid shorting the connection on the amp.
     
  5. Ken, before I just now looked for a definition, I knew inrush to be the amount of current that is drawn into the unit to charge the various capacitors and such so that the amp is ready to perform.

    As I understand it, the Stewarts latch onto the main AC as soon as you plug it in whereas most units start drawing only after the unit is turned on. The Stewart's instructions state that about one minute is needed after you plug it in for the amp to bring itself into "ready" mode.

    After doing a search I came up with this:

    From www.systemconnection.com/downloads/poweradapterkb/switchingtransfo.html
    "When a power supply is first turned on there are a lot of capacitors and inductors that are empty. Inrush current is the transient amount of current that it takes to charge these capacitors and inductors and thus start up the power supply."

    And from Wikipedia
    "Inrush current or input surge current refers to the maximum, instantaneous input current drawn by an electrical device when first turned on. For example, incandescent light bulbs have high inrush currents until their filaments warm up and their resistance increases. Power converters also feature high inrush currents relative to their steady state currents. This is typically the charging current of the input capacitance."

    zombywoof: Yes, I've tried the power strip trick to no avail. Again, this isn't something that's happening every time. I hardly ever use it anymore so I don't deal with it much. I even had trouble with it plugged into a Furman AR-1215 voltage regulator. I would plug it into the unit and then turn on the regulator and sometimes it would still trip a breaker. :mad:

    Thanks, guys! :)
     
  6. Oh and BTW, no problems whatsoever with my WW! She runs clean as Willie's veggie car!
     
  7. landru64

    landru64

    Mar 6, 2005
    fyi. it says on my new Ultra manual/warranty (3 weeks old) that "Use of the preamp section only without both post gains at zero and without connection to a speaker will also void the warranty"

    maybe talk to walter directly about this stuff?
     
  8. Interesting... that's something new for Walter. A lot of us have been running his amps as preamps into a board with no load for years and years. Per our recent Walter mega-thread, I wonder if this is due to the change in design for the Ultra's that happened a couple of years ago?
     
  9. landru64

    landru64

    Mar 6, 2005
    maybe so... i'm not sure how long ago he started making this warning. i have a stereo greenlight amp that's not more than a couple of years old and it doesn't have any such warning.

    has anyone compared the current ultras to previous ones sonically?