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  • Help me please! Problem with SPX900

    Hi,

    I did sound for our gig last saturday, and I've found that there is a trouble with my Yamaha SPX900.

    The trouble which I've found is the "noise". Awful digital noise... Very annoying. I thought I'd fried my speakers first, but then I realized the problem was coming from a stereo channel (15/16ch- fx return) of my CFX20.

    My SPX was +4 mode and I feed from CFX's post aux, then return to a stereo channel. The gain pot of the stereo channel was quite low and fader was at U. The input of my SPX was about 12 o'clock.
    And balanced cables was OK...

    What do you think the problem is ? Do I have to replace with a w unit??? Or should I need to clean the print board and jackes???

    Thanks in advance

    YOSHI

  • #2
    The SPX-900 is one of my favorite units... and this is a common problem.

    I'll bet that your console was still set with too much input gain. The 900 on +4 mode will really put out +4 so typically, you will need to run the input trim all the way down AND the pad on. This will put you at +4 sensitivity on most consoles. This will mean that yo will need to drive the input to +4 also, so gain structure will be important. Since channel effects sends are post chanel fader, running with channel fader and/or trim on input channels very low may not generate enough drive signal on some (typically lower grade) consoles. Be sure that you see the -10 led flash on the 900 input otherwise s/n ration will suffer.

    Also, be sure that you are not sending phantom power to the 900. I don't think it likes phantom, and may also cause noise problems by interfeering with the servo balancing circuit on the 900's balanced output line driver.

    Hope this helps.
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

    Comment


    • #3
      Thank you, Andy..

      I was feeding 3 vocals (one main vocal & 2 backup vocals) to my SPX900 through a post aux mix. I set the main vocal channel fader at U and the rest were at around -10. All channels were far from clipping level. The post aux send was about 9-10 o'clock at channnel stripe and U at aux master.

      I use a stereo channel to return from the SPX and gain trim was at about 8 o'clock. The fader was at U. Input of my SPX was at about 12 o'clock and the wet:dry ratio is 50:50.

      Do you think I was putting to much to overload my SPX?

      I know that my console isn't the best one, but they (CFX and SPX) usually work great enough.

      YOSHI

      Comment


      • #4
        Yoshi...

        I did the same thing with my Rev 7 when I used my CFX20. First off, you should have the wet/dry mix set to 100% wet for the return.

        You should use the EFX 1 send of each channel, this is pre-fader.
        The EFX 1 on the vocal channels should be a unity. The EFX 1 send(master section) should be a unity. When your returning to the stereo channels, The gain should peak at 0 when soloing.

        Be sure you have EFX 1 return OFF. Assign the return channels to the same group at the vocals. You'll control the the amount of effects sent to the mains with the channel fader. All the way down is off, unity is a 50/50 mix send to the mains.

        Make sure you don;t have the EFX 1 send on the return channels on. If you do, you'l have an extremely nasty feedback loop.
        www.thebritins.com
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        • #5
          Originally posted by MichaelSTE
          Yoshi...

          I did the same thing with my Rev 7 when I used my CFX20. First off, you should have the wet/dry mix set to 100% wet for the return.

          You should use the EFX 1 send of each channel, this is pre-fader.
          The EFX 1 on the vocal channels should be a unity. The EFX 1 send(master section) should be a unity. When your returning to the stereo channels, The gain should peak at 0 when soloing.

          Be sure you have EFX 1 return OFF. Assign the return channels to the same group at the vocals. You'll control the the amount of effects sent to the mains with the channel fader. All the way down is off, unity is a 50/50 mix send to the mains.

          Make sure you don;t have the EFX 1 send on the return channels on. If you do, you'l have an extremely nasty feedback loop.

          Yes, agreed!
          Also, be surethat you are seeing an input signal peaking around -10 on the SPX's input meter.
          -------------------------------------------------------------------------------------------------------------------------------------------------------------------
          Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

          Currently product development engineer: Mesa Boogie

          Comment


          • #6
            Michael and Andy,

            Thank you for your advice!! I'll try your suggestions at next gig.

            Best regards

            YOSHI

            Comment


            • #7
              Hi,

              I've solved my problem. My aux output signal (Efx1 output) was way lower and I had to increase the gain at input pot of my SPX and the return channnel gain pot.

              Now I set my aux send and maset at "U". Healthy signal goes to SPX (above the "-10" position) and very sexy reverbration is coming back to my mixer.

              Thank you!! This (HC) is really great board for a newby like me!!


              Yoshi

              Comment


              • #8
                Originally posted by whsjosh
                Hi,

                I've solved my problem. My aux output signal (Efx1 output) was way lower and I had to increase the gain at input pot of my SPX and the return channnel gain pot.

                Now I set my aux send and maset at "U". Healthy signal goes to SPX (above the "-10" position) and very sexy reverbration is coming back to my mixer.

                Thank you!! This (HC) is really great board for a newby like me!!


                Yoshi

                This is a common problem with both the SPX line AND many modern (but wimpy) consoles that do not contain enough gain at typical operating control positions to achieve +4.

                By the way, you have have a great pro audio and MI dealer in Osaka for many products (including ours). It's "E-Spec", and they are really sharp guys for figuring out technical problems.
                -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                Currently product development engineer: Mesa Boogie

                Comment


                • #9
                  Andy,

                  "E-Spec" is a one of the good local pro shops in Osaka. I'm planning to update my Mackie to something better at "E-Spec" in the future. Now soon.... I need more lessons!!

                  Yoshi

                  Comment


                  • #10
                    E-Spec is the Japanese distributor for the Genz Benz product line that I design for. They seem to run a very nice operation.
                    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                    Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                    Currently product development engineer: Mesa Boogie

                    Comment


                    • #11
                      Hi,

                      My SPX started making noises again. I found the noise was coming only from the L channel. The gain sturucture was fine. So I opened the unit and found 2 cold joints near the L output.

                      I just re-solderd, then all the noises have gone !!

                      My SPX is quite old. I guess the solder point went bad by its age...


                      YOSHI


                      PS: Andy, I've just bought a new mixer at "E-SPEC". They gave me the best price !!

                      Comment


                      • #12
                        Originally posted by whsjosh
                        Hi,

                        My SPX started making noises again. I found the noise was coming only from the L channel. The gain sturucture was fine. So I opened the unit and found 2 cold joints near the L output.

                        I just re-solderd, then all the noises have gone !!

                        My SPX is quite old. I guess the solder point went bad by its age...


                        YOSHI


                        PS: Andy, I've just bought a new mixer at "E-SPEC". They gave me the best price !!


                        Yes, that is a common problem with the Yamaha products (AND many others) since they use a paper-phenolic laminate pcb material with soldermask over bare copper on many products such as the 900. Glad that the noise reappeared. It's hard to solve the problem on an intermittent unit.

                        Glad to hear about your new mixer. Joe Akiyama is a very good resource and is technically very knowledgeable about the equi-ment his company sells, and they are extremely competative also. He is also a really nice guy. Did he show you any of the Genz Benz product he represents over there?
                        -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                        Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                        Currently product development engineer: Mesa Boogie

                        Comment


                        • #13
                          Cold solders on Yamaha products...... Every piece of processing I have ever owned from Yamaha had this problem after a few years. If you have it apart you might as well do them all.

                          Comment


                          • #14
                            Originally posted by J Kylez
                            Cold solders on Yamaha products...... Every piece of processing I have ever owned from Yamaha had this problem after a few years. If you have it apart you might as well do them all.

                            It really depends on the piece... not all of them are a problem. Thi Chinese stuff like the new MG series mixers will not have that problem since they use a really good quality pcb, 2 sided and plated through. A very impressive piece for the price.
                            -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                            Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                            Currently product development engineer: Mesa Boogie

                            Comment









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