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  • Vox Continental - High Pitched Noise

    Hello!

    I recently picked up a 1965 UK Continental and I'm just absolutely in love. After getting well acquainted with it however, I did discover that there were some scratchy/intermittent notes. I proceeded to fix them with contact cleaner. One of them was extra fussy and I actually had to dissemble the contact box completely to fix a cold solder joint on one of the contacts to get it perfect. That was a very tricky repair indeed, but I can't get that note to fail anymore (yay)

    After finishing all my work, I noticed that there's a very subtle high pitched noise that's constantly ringing. Doesn't seem to matter what keys I play or what drawbars I engage. It's always there. You reaaaaaally have to listen for it though -- reads under -60db. But I don't think it was there before I started working on it. I did a little recording with it when I first got it and listening back to that, I can't hear it in the silent parts of that recording. I recorded DI by the way. I can make it out while it's DI'd and through an amp.

    It's so quiet that when I'm playing even the quietest note it's drowned out completely... so I could totally live with it. But being quite certain that it was dead silent before all the work I did makes me want to sort this out for sure.

    Any idea what could be causing this?

    Thanks so much,

    - Jay

  • #2
    I was going to guess that you have a cipher, a key with a contact that is misaligned, and it continues to make contact with the buss bar even when the key is not pressed. But you say it doesn't matter which drawbars are engaged. To help me understand, if you pull out the four leftmost drawbars one drawbar at a time, do you hear this sound on each of the "solo" drawbars?

    If so, I have another theory...

    Alan
    Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
    See a preview: ClassicKeysBook.com
    Buy it now: www.amazon.com/dp/1574417762

    Comment


    • #3
      Edit: After further investigation, I noticed that the sound was being effected by the vibrato switch and it sounded like a high C note, which would likely suggest another contact issue. By the time this post was approved (about a day after submitting it) the problem had sorted itself out. If I had to assume, it was probably just some left over contact cleaner from the repair before that may not have dried completely and was possibly triggering some of the contacts. Hope this post helps someone else that may experience the same thing!

      - - - Updated - - -

      Thanks for the reply, Alenhoff! The problem is now solved (I posted an edit). Indeed, I was able to hear the sound no matter what I did. Even if all the drawbars were set to their lowest setting. I don't remember if I tested turning off the tone bars though...

      Comment


      • #4
        Good to hear you have it sorted out. I love my '65 Continental!

        Alan
        Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
        See a preview: ClassicKeysBook.com
        Buy it now: www.amazon.com/dp/1574417762

        Comment


        • #5
          Update! The sound has returned... it's quieter this time though (-72.2db) but I can definitely pick it out in my quiet studio. Since it's acting up again, I decided to test it a little more carefully: I can make it measurably quieter (not audibly) by pushing the ~ drawbar back, but it doesn't go away completely. Besides that, the story remains the same -- adjusting the other drawbars doesn't make it louder or quieter and the tone is effected by the vibrato. I recorded it into my DAW and gained it up a ton so I could confirm what note the ringing tone was. The fundamental reads roughly 4201.4hz on my EQ which as speculated earlier is nearly a perfect C8 (4186.01hz). There are some upper harmonics I could see in the EQ too but they're not audible. How strange! All that being said, the thread's back in action... thoughts?

          Thanks again,

          Jay

          Comment


          • #6
            This may be above my pay grade. But since this happened after you worked on the key contact assembly, I would suggest that you first rule out any problem with the contacts.

            With the keys at rest, each of the contacts should make good contact with its respective ground bussbar. When you press a note, each contact should make good contact with its playing bussbar (did I just make up that name?), and if drawbars are pulled out, the note will sound. When you release the key, if any contact is still touching a "playing" bussbar, you get a cipher, and the note still sounds when the key is released. (This is what I thought your problem might be, except that the note would not likely be so low in volume, nor would it be out of tune.) When you release a key, if any of the contacts fail to make good contact with their ground bussbars, you can get all sorts of stray sounds. This is really critical to having an organ that is silent "at rest."

            So, my first suggestion would be to make a careful inspection of the key contacts at rest, and make sure all of them are making good contact with their ground bussbars. If you see any that look like they might be barely touching, use a finger tip to press them against the ground bussbar and see if the stray sound goes away.

            Alan
            Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
            See a preview: ClassicKeysBook.com
            Buy it now: www.amazon.com/dp/1574417762

            Comment


            • #7
              If it were caused by a faulty contact, you'd expect the sound to go away when all the drawbars are retracted though... right? Maybe not! I'll post an update after I give this a shot. Also, I took that recording and digitally pitched it down 2 octaves so my guitar tuner could read it and it is a perfect in tune C after all. So this could still be a very plausible cause. Thanks Alan.

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              • #8
                Just one other thing to check, are you sure it is not just normal background chatter from the transistors? The Farfisa Compact Range that I am familiar with often have some background “crosstalk” for want of a better word. It is noticeable with full swell and reverb engaged. It always shows as a small signal fluctuation in my DAW.
                Hammond C3, M102, XB3, XB5, X5
                Lowrey Heritage DSO-1, H25-3, Yamaha E70
                Farfisa Compact Duo Mk2, Vox Continental 300, Korg BX3 Mk1, Leslie 122, 145, 910, 415
                www.drawbardave.co.uk

                Comment


                • #9
                  Hm... that I'm not sure! Considering just how quiet it reads on my meters, it very well could be. My only doubts are due to the fact that it's pretty recognizably a ghost C note and not just a very quiet cloud of cross-talking notes, which is would I would expect something like a background chatter to sound like. Also the sound has gone away and come back before. I'll try out your solution and see what happens :) Would it help if I sent an amplified recording of the sound?

                  Comment


                  • #10
                    I'm familiar with the background "beehiving" on Farfisa Compacts. But I've owned six Continentals in recent years, and if they are working properly, they are totally silent when idle.

                    (Actually, I kind of like that sound on the Farfisas -- not to mention the cool sound you get when you hold a chord and turn off the power.) ;-)

                    Alan
                    Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
                    See a preview: ClassicKeysBook.com
                    Buy it now: www.amazon.com/dp/1574417762

                    Comment


                    • #11
                      Yeah... this is definitely something weird. I tested every contact. First by just pushing each key in on the little metal comb thing, but then went even more in depth by using a guitar pick and pushing each contact right against the ground buss bar to make sure the issue wasn't one of them not grounding out properly. Didn't change anything. However, I did notice that if I press the highest C key down enough that the contacts lift off the ground buss bars but don't hit the hot, the sound drops dramatically. Enough that I can't hear it anymore, but it does still read in my EQ plugin. Doing so on the second highest C note also seems to have a similar effect. Maybe it's a grounding issue only effecting the C tone card?

                      Edit: It's DEAD silent when I tested it with the C tone board completely removed.
                      Last edited by JayCrafton; 12-19-2018, 01:30 AM.

                      Comment


                      • #12
                        Originally posted by JayCrafton View Post
                        Maybe it's a grounding issue only effecting the C tone card?
                        Excellent information.

                        Vox's plug-in card design is really convenient for servicing, but makes it easy to have bad connections between a board and the wiring loom. So lets explore what can go wrong there. With the card installed, the fourth pin from the right is the ground connection. Sometimes the pins get dirty. Just pulling the card in and out a few times can often clean the pins, but to be sure, use a little contact cleaner on them. Still hearing the sound? Is the ground pin properly soldered to the board? Inspect the traces connected to that pin for breaks. Is the pin making good contact with its receptacle? (Sometimes pinching the receptacle gently with needle nose pliers can tighten it up a bit and help it make better contact. Is the ground wire properly soldered to the pin receptacle?

                        I think you're getting close here...

                        Alan
                        Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
                        See a preview: ClassicKeysBook.com
                        Buy it now: www.amazon.com/dp/1574417762

                        Comment


                        • #13
                          Alright, I really gave those sockets a good cleaning and made sure the solder connections were strong. I reflowed the ground wire (fourth from the right as you said) just to be sure, but all that work didn't get rid of the sound. However, I did notice that if I short the second and third pin from the right with an x-acto blade, or the third and fourth, the sound goes away completely. I did all this while looking at the analyzer in my EQ. After grounding it, all that was left was an incredibly minuscule hiss which I'm certain is normal. We're talking like -90 db. Completely inaudible unless the preamp is maxed out. At that point, the preamp itself would be making more noise! There are no other visible broken wires I can see, but there are a lot of wires that go behind the tone cards that I'm not even sure how to get to. Would there be any ill effects if I were just to add a little wire shorting out those pins? Or am I better off really getting behind there and making absolute sure there's no broken wire. I've attached two pictures of me shorting the pins as well as two pictures of my assistant. His specialty is in moral support.

                          Edit: Shorting the pins will not work... oh well. It solves the ground issue, but it also causes some of the notes to not play properly. Should have expected! Must be a broken wire I haven't found?

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                          • #14
                            Your assistant appears to be somewhat disinterested. Tell him/her to get with the program! Some thoughts:

                            Have you checked that the wire soldered to Pin 4 is actually connected to ground? It should show continuity to the Pins 4 on each of the other TG boards.

                            You mentioned that you re-flowed the "ground wire" (singular). On my boards, there are two wires (both white) that are soldered to Pin 4 on each TG board. (Your color code may be different. Unless your organ was re-Tolexed, it appears to be a 1966 model. Mine is a '65.) If you only have one wire soldered to the Pin 4 socket, take a look at the same pin on other boards. Any dangling wire near the C board?

                            The quickest way to determine whether a fault is on a board or somewhere "downstream" of it is by swapping boards. Move the C board to the C# socket and vice versa. If you suddenly hear a stray C# sound, the issue is somewhere in the C wiring or contacts. If you still hear a stray C sound, the issue is something on the C board.

                            My guess here is that while I apparently know Vox organs better than you do, you may be far more experienced in electronics. Do you have a schematic? If not, I can provide one to you. (PM me with your email address and I'll send it to you.)

                            Alan
                            Co-author, "Classic Keys: Keyboard Sounds That Launched Rock Music."
                            See a preview: ClassicKeysBook.com
                            Buy it now: www.amazon.com/dp/1574417762

                            Comment


                            • #15
                              Oops! Sorry for the confusion. I indeed have two ground wires and they're both red on mine. Anyway, I checked for continuity on the fourth pin of each tone card (putting one of the multimeter leads on pin 4 of the C card and the other on pin 4 on the C# card for example) and that's definitely there, so that's cool! Also, I tried swapping the C and C# cards and it turned into a ringing C# note. Smart idea! So it would indeed make sense that there's something going on specifically in the C wiring. Pretty sure contacts are totally ruled out at this point due to the information gathered from all the previous tests I did trying to see if it was a cipher issue. I may just try desoldering and resoldering those two ground wires to the pin 4 tab just in case it's maybe a cold solder joint and the two wires aren't properly fused together anymore. Before I try that though, I'm curious what your next steps would be... thinking I might just have to take everything apart and see exactly where those two red wires come from. Also, on one of the points you raised, I've only done guitar electronics and very basic house wiring up until this point. More advanced repairs like this are certainly new to me and I'm just getting my feet wet in the world of amp and synth repair! I'm finding it really interesting to learn how these instruments work.

                              Jay

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