That's very not normal. The sound from WOz is usually quite good.

Try the headphone jack and see if it's buzzy there, too?

Check your connectors. One is loose. From the speakers to the amp to the coin door.

As Pinchroma says, first make sure all the audio cables are attached firmly.

Even with that, however, both my game and a friend's game had a distinct hum coming from the speakers, that was related to how many LEDs were lit at a given time. In the menus, all three colors of every LED will be lit, so this is the worst case.

In both our games, we were able to get rid of nearly all of the noise by taking the ground loop isolator (black box on the right side of the metal box) out of the audio path and re-routing the cable that runs from the PC motherboard to the pink jack on the amp. The exact location that worked for the two games was different, and we were able to find the sweet spot by moving the cable around while the game was on and in the menus.

Here are some pictures of what I did to my game, but yours will likely need to be routed slightly differently.

IMG_2451.JPG

IMG_2452.JPG

IMG_2453.JPG

HI Guys.
I recommend leaving the isolator in to keep the LED noise currents out of the Amp input. The transformer stops LED any current from flowing on the ground of the audio cable. If ground current exists, the current will couple into the L+R audio +inputs.

I agree with rerouting the audio cable. Move the cable out of the bundle it's ty-wrapped to. This will prevent other LED noise from coupling into the cable. (Thanks to Dave for finding this).

There are two methods being used to get the audio from the CPU board to the isolation transformer.
#1. Female connector that is pressed onto the audio out header connector on the CPU. (Shown in the pictures above)
Keep an eye on this connector. If you find that wiggling it makes the audio cut in and out then you have a poor connection. I recommend swapping the cable to method #2.

#2. Later games tap the audio out on the 3.5mm Green connector on the back of the CPU. It's a better connection (IMO) BUT it's not perfect. Wiggle that connection and if your cabinet speaker cuts out then your connection is not great. Some of the 3.5mm audio cables used have a slightly smaller diameter ground barrel and this causes the ground to open up causing static noise in the audio and the cabinet speaker output to drop. Position the cable so you get a good connection for now.
Thanks,
Mark

Mine is one of the games Herg is referring to that we removed the isolator and re-rerouted and eliminated pretty much all the noise.
My question is why not use a shielded cable to reduce electromagnetic coupling noise? The isolator did not appear to have any effect on the speaker hum caused by the LEDs. If anything, the isolator appeared to have made it worse.

The cable should be shielded but I have not dissected one to make sure.
A shielded cable will not help with magnetic coupling. It will help with capacitive coupling.
Here is how I understand it. A magnetic field in proximity with the shield of the cable will induce a current on the shield of the cable. In this case, the voltage difference across the ground of the CPU board and the Amp causes a current to flow in the ground shield of the cable…which may couple onto the L+R audio lines.
Even with the isolation transformer in place, there is still a small ground loop present through the L+R input impedance. I suspect this is what might be picking up the other noise.
I did some testing on my machine and I did get a good reduction in LED noise when I used the isolation transformer.
I suppose there may be cases where it behaves differently. I'm open to understanding how and why.

One more question. Does your game sound reasonably loud when you set the volume to 30?

Thanks,
Mark

When you say loud, do you mean the signal volume or the noise volume? At setting 23, which is pretty loud, that is about as loud as I want the game in my house. Also, with the isolator removed, the sound at 23 in the re-routed position is essentially noise free.

Signal Volume.
I'm running my System volume at 30. That's about my comfort limit in my basement.
I don't hear any noise at that level.
I'll play around with my cable the next time I have the glass off.

Well sound like you are in good shape.

Thanks,
Mark

Here is some general info about audio cables and how shielding on an audio cable can ground/shunt out unwanted electromagnetic interference (or radiation):

http://www.bluejeanscable.com/articles/humrejection.htm

Hey guys. I just wanted to resurrect this thread since I just ran into this issue with a HUO standard WOZ I picked up. The buzzing from the speakers was really bad. Bad enough to where I couldn't even start playing the game without fixing it first. The posts above may be talking about the same fix here, but I couldn't really tell. I just thought my take on it might help some others with the buzzing noise.

Here's what I did to fix it.

1. Pull off CPU box cover in the bottom of the cabinet.
2. Cut zip tie off the noise isolator/ground loop isolator (pictured above). This is the little black box on the right side of the CPU box, about 1/2 way up. There is a black 3.5mm wire coming off the sound board that goes into and out of it.
3. Lay the noise isolator flat at the bottom of the cabinet and zip tie it as low as possible back to that white/creme plastic, away from the wires above.
4. Cut the zip tie above the noise isolator that is holding in the two black speaker wires. Re-route these away from the noise isolator box. Zip tie them out of the way. There wires are running along the right side of the CPU box and out a hole in the back above the fan. So make sure to zip tie them out of the way of the fan. You wouldn't want those to fall and stop the fan from cooling. I ran them up the center of the CPU box all the way to the back of it, then a 90 degree turn over to the exit hole.

So basically all you are doing is moving the noise isolator lower away from wiring, and then moving the two black speaker wires away from that box.

After I did this, I have absolutely zero speaker buzz at all. I hope this all makes sense. Feel free to ask me any questions. I can also try and shoot a short video to explain if anyone wants me to.

A short video would help...I'm getting a hum when all LEDs go white in test mode. Does this fix that?

He is correct,move the noise isolator. You will be amazed! I did it months ago after many hours of trying different things.

Yes. Mine was humming/buzzing pretty loud when in test mode and all LEDs white. No noise at all now. I can toggle the speaker mute button now and not even know when it's muted or not.

I'll try to take a quick video of it tonight.

Here's a video.

Great video--thanks!

Wanted to resurrect this thread. Played a WOZ locally, couldn't hear any sound and only static. Is this the right place, or is it a different issue?

Finally got around to doing this and just moving the noise filter from vertical to horizontal eliminated 99% of the speaker buzz. Found out my wire ties are out so I didn't move the cabling yet. Don't know if I'll even bother though because it's pretty much quiet except for that fan. Thanks for the video!