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Low output from Eden WT800 in Bridge Mode

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  • #31
    Originally posted by Helmholtz View Post
    I don't see a reason why the phase of one scope channel should jump if you leave both probes connected to left and right outputs. Maybe some trigger instability. If the two outputs would actually be in phase, current would be zero.

    BTW, there is no reason to not connect the probe grounds to the amp's ground. Just never connect probe grounds to one of the (hot) output terminals.
    Hey, I thought I heard a click coming from somewhere! haha. I think it may have been from the scope. I was still reading current through meter, so I guess the phase didn't flip after all. Geez.
    I always believed that in bridge mode, one should NOT ground the scope probes.
    I'm learning some stuff here. Thanks!

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    • #32
      Originally posted by nevetslab View Post
      I think in this setup with the 5-Amp Variac, it's core is saturating, since your amp at full power is pulling too much current thru it. What did you measure unloaded in Bridge Mode?
      Measured around ~95V across terminals (no load). I always thought I needed a load to determine anything. Can you explain what this no load voltage means?
      Man, you guys are inspiring me to bring out all my electronic books I've acquired but never read in depth.
      I'm in awe of the knowledge here on this forum.
      The reason it was brought to me is the guy thought it lacked in power.
      Just wondering if these measurements I've been posting are that of a correctly working bridged 800 watt amplifier.
      Sorry, I just don't work on a lot of there high current SS amps to be totally confident to tell owner to pick up.
      Last edited by Stan Keith; 03-27-2020, 03:46 AM.

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      • #33
        Originally posted by Stan Keith View Post
        Measured around ~95V across terminals (no load). I always thought I needed a load to determine anything. Can you explain what this no load voltage means?
        Man, you guys are inspiring me to bring out all my electronic books I've acquired but never read in depth.
        I'm in awe of the knowledge here on this forum.
        The reason it was brought to me is the guy thought it lacked in power.
        Just wondering if these measurements I've been posting are that of a correctly working bridged 800 watt amplifier.
        Sorry, I just don't work on a lot of there high current SS amps to be totally confident to tell owner to pick up.
        One thing the no load measurement tells me is the amp IS working correctly in Bridge Mono mode. With no load, you don't have the copper losses that loose power under speaker-driven loads. You no doubt saw clean & significantly higher output swing vs the loaded condition. Without using your 5Amp Variac, you'd get higher output since there isn't the copper loss in the variac to loose AC mains voltage. As for the Eden WT800, I'm always amazed they work as well as they do, with so few output xstrs in the output stage. But, there is a VERY large Toroidal Power Xfmr in it, and they do kick butt quite well. And, like most solid state power amps, they do sound better in Bridge Mode...more head room! It might be the guy who brought it to you felt it lacked power relative to an even higher powered amp.
        Logic is an organized way of going wrong with confidence

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        • #34
          Originally posted by nevetslab View Post
          One thing the no load measurement tells me is the amp IS working correctly in Bridge Mono mode. With no load, you don't have the copper losses that loose power under speaker-driven loads. You no doubt saw clean & significantly higher output swing vs the loaded condition. Without using your 5Amp Variac, you'd get higher output since there isn't the copper loss in the variac to loose AC mains voltage. As for the Eden WT800, I'm always amazed they work as well as they do, with so few output xstrs in the output stage. But, there is a VERY large Toroidal Power Xfmr in it, and they do kick butt quite well. And, like most solid state power amps, they do sound better in Bridge Mode...more head room! It might be the guy who brought it to you felt it lacked power relative to an even higher powered amp.
          Speaking of copper loss, the mains voltage drops 5 volts as I near clipping. Difficult to get a good reading, so I guess I can tell him it's in the ballpark at this point.
          And maybe I should talk to my landlord about the 1930s area wiring. haha
          Thank you so much for taking time to guide me through this.
          I learned a few things.
          You, and the others who posted here are some cool dudes!

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          • #35
            might be the guy who brought it to you felt it lacked power relative to an even higher powered amp.
            Actually, he thought his lower powered amps sounded louder. So that's why I'm reluctant to give back to him.
            Is it possible some of the current load is coming from "copper loss" within the toroidal transformer?
            Or, being that I'm getting a clean signal up to the shortcomings of my AC source, and measurement equipment, I'm likely in the "ballpark," and ready to hand back to owner?

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            • #36
              I got a little behind on this one, sorry. Your 7.3ohm load calculation means your 72VAC was producing around 710watts. Very close. You said your mains voltage was sagging which would probably make up for the rest. Not sure why you are using the variac at this point, you shouldn't need it. (unless you are trying to make up for very poor mains voltage).
              If you still have the amp, here's something to try as far as the phasing. Same setup bridged into load but put ch.1 scope probe on input signal. Ch.2 probe first to (+) output, then move it to (-) output. One should be in phase with input, other should be out of phase.
              "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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              • #37
                Originally posted by g1 View Post
                I got a little behind on this one, sorry. Your 7.3ohm load calculation means your 72VAC was producing around 710watts. Very close. You said your mains voltage was sagging which would probably make up for the rest. Not sure why you are using the variac at this point, you shouldn't need it. (unless you are trying to make up for very poor mains voltage).
                If you still have the amp, here's something to try as far as the phasing. Same setup bridged into load but put ch.1 scope probe on input signal. Ch.2 probe first to (+) output, then move it to (-) output. One should be in phase with input, other should be out of phase.
                Yes, I tried all of your suggestions. Everything is in phase (or out) as designed.
                I was using the variac to make up for the drop in line voltage, but only for a few seconds. Variac is rated for 5 amps, so didn't trust for accurate measurements.
                Thanks for your help.
                Really appreciate it.
                Stay healthy.
                Stan

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