Wurlitzer 200a grounding? or normal...

[garagebandking41]

My wulri 200a's line out has a lot of hum/hiss. the volume of the hiss is constant from 0 volume, to 100%. it's even there when the amp is off. of course, when i unplug the wurli from the wall, there is no hum.

I was wondering what could be causing this type of hum/hiss. its alright in some amps, but very noticeable in a recording setting, or on PA's. I've looked for any loose grounds, but Im a bit inept when it comes to troubleshooting something like this...

[pianotuner steveo]

In general, the first thing always recommended in wurlis is to replace the caps. Old dried out caps will eventually cause other problems, so I would check into that.

[garagebandking41]

Could old caps cause this symptom? Considering the hum is still there when the power is off, i would think it was a grounding issue. But you're right, I've been wanting to do a rebuild anyways, just didnt think the caps would cause hiss when the power was off.

I've done some minor stuff like replacing the soldering in fuses with easy access ones, and i've been meaning to get a new pre-amp for it as well. I'm trying to make the darn thing studio ready, so i can make some recordings...I should have stuck with just Rhodes...hah!

[pianotuner steveo]

I find it odd that you hear hum if the power is off.....is the hum through the speakers or is it coming from the transformer?

[jim]

I'd really like to know the outcome of this, am having exactly the same problem.

[jim]

bump bump bump?

[jim]

really? nobody has anything?

[pianotuner steveo]

Jim, in your case, could it have anything to do with you being in Australia?

( The difference in your electricity,with whatever transformer you use?)

Just for the record, what is the electrical standard in Australia? Is it 220v 50 Hz?

[jim]

Hi Steveo, long time no chat!
we are 240V down here.
the transformers in our wurlys are different, but i've played others without this sound many times so it doesn't seem to be an australian thing.

If this where a passive rhodes i'd be putting my hands all over it trying to lower the noise by grounding it. But I'm not doing it on a wurly! i'm scared!

[Legato72]

Same issue here. (and I'm American thus 120 V.) Even when the wurli is off and it's plugged in an amp it will have horribly loud hum. I had always figured it was because mine is a 200 and needs the AC fix where you twist the wires and shield them, then replace the neon bulb. That doesn't make sense on second thought, because it hums when its off. I'm a little shocked to hear someone with a 200a having the same issue. I'm doing a lot of fixes to it right now and I am checking all the grounds, I'll let you know how it goes. won't be done for a while though, have an amp rebuild ahead of me.

[Legato72]

I have successfully installed the VV hum killer kit into my 200. In the back of my mind the whole time I was installing it I thought it probably won't fix this problem, because it still hums when the wurli is off, and is unaffected by the volume knob. I was right.

The obscenely annoying hum is still there. It's sounds like when you hold your finger on the end of the 1/4 inch guitar cable when it plugged into an amp. Also please note that this only happens on an external amp plugged into the aux (or headphone) jack. This hum doesn't exist on the on-board speakers.

I checked and double checked all my grounds. I can't figure out what it could possibly be if it seems to be grounded alright. It cant be the transformer because that's only activated when you turn the switch. As the topic author stated, when you pull the power cable it stops.

Maybe a bad input cable? the one that runs from aux to the circuit board? but the headphone jack causes hum too. A real head-scratcher.

[Legato72]

GROUND LOOP.
The issue is a massive ground loop. A circuit formed through the grounds between my vibrolux (external amp) and my wurlitzer. To solve the problem I went to Lowe's and got myself 3 to 2 prong ground lifter for 77 cents. put it on the end of my wurli power cable and problem solved. all that awful hum disappeared. I imagine you could also solve the problem with a guitar cable that is tip only on one end, not having the ground connected on one end of the sheild. I think that too would eliminate the loop, but it is a lot easier to just use a ground lifter. Its still safe because the wurli then becomes grounded through the external amp.

Again, if you are having external amp hum that is constant no matter the volume of the wurli (or if it is switched off even), you have a ground loop. I can't believe this isn't a more widely known issue in the wurlitzer community. but then again, maybe its so obvious to some people its not even worth mentioning.

EDIT: Don't quote me on the safety thing. I'm actually not sure how safe it is exactly.. a guitar cable that is only tip and no ground on one side would probably be "safer" because you eliminate the loop and both the amp and wurli would be grounded safely to the wall on their own. But then that cable becomes purposed soley to plug the wurli into an external amp.

[pianotuner steveo]

That is great news. I have been collecting Wurlis since the 70's and have never heard of this problem before this thread, and I dont think it was ever brought up on the yahoo wurli board.

[mickeyziggyk]

Hi

My first post.

Not wanting to start a new post, but i have this issue too.

Wurli 200a on the headphone output with power on or off hums like crazy through certain amps.

To a normal guitar amp it is fine (koch se6 or orange crush), but to a hifi,  class d yamaha amp or a hifi or an elektron octatrack it hums like a giant bee. It's also fine with headphones. I've noticed that the aux output does not have this issue at all just the headphone out.  Naturally if I disconnect from the mains, the issue goes away too. Passing the signal to a radial jdi sorts it out too but then the signal is very quiet and needs a heap of boost.

It's quite bizarre. As a workaround I'm thinking of disconnecting the internal speakers so i can use a quiet line out.

Would anyone care to comment on the quality of the signal via headphone or aux as the aux out seems more 'open' in its quality and the headphone out seems 'narrower'.

[pianotuner steveo]

The headphone out should not be used in lieu of a line out. The signal is hotter, and can distort easier.
That's my 2 cents worth.

It sounds like you may need to ground your power cord also?

[mickeyziggyk]

Thank you for your input Pianotuner Steveo

I decided to mod my wurli and add a switch to kill the speakers so i can have dedicated line out via the aux.

I'm not good at these sorts of things but I've got it working and for my 200a and I'm very happy with the sound via the aux than the headphone. Just in time for a wee jam, as the fellas should be round soon.

The reason i want a dedicated line out is that i love fx and processing the wurli via delay, vibrato, phase, chorus, filters, volume pedal, and synths.

And the reason i posted is that maybe someone else whi is struggling to get a good line out signal might come across this post, as the previous posters helped me.

[cinnanon]

You didn't need to add that switch. All you needed was to plug in a 1/4" to 1/8" stereo adapter

[Max Brink]

I have successfully installed the VV hum killer kit into my 200. In the back of my mind the whole time I was installing it I thought it probably won't fix this problem, [because it still hums when the wurli is off, and is unaffected by the volume knob. I was right.]

Wurli 200a on the headphone output with power on or off hums like crazy through certain amps.

...If the Wurlitzer is off and you still have noise it is definitely because of a ground loop between the Wurlitzer and the amplification circuitry. Wurli's are incredibly prone to electromagnetic interference and ground loops just due to their design. Where to address this symptom within the instrument is going to be hard to diagnose over the internet and if you're uncertain I would take it to a Wurli expert or EE.

I imagine you could also solve the problem with a guitar cable that is tip only on one end, not having the ground connected on one end of the sheild.

^^^I would be very surprised if this ever works. Respectfully, to the person who wrote this years ago, I wouldn't try this ever.

[pianotuner steveo]

I agree with Max on that last point, I don't see how that would solve anything.

[agarcia]

Old thread but figured I'd give my thoughts on troubleshooting a ground loop issue.
First thing to try with a ground loop is making sure both the wurli power cord and the amp power cord are on the same outlet or right next to each other in a power strip.
This reduces the length of the loop path and should help mitigate the issue, but there will still likely be hum.

Personally, my favorite way to break a loop is to buy line isolator. They're kind of like a DI box but with 1/4" in and 1/4" out (instead of xlr).
These are pretty much just a transformer that provides isolation between the wurli output and the amp input and keeps their grounds on either side of the transformer. ex. Radial Engineering makes the SB-6.

While theoretically the cable with shield connected on one side should work, if done incorrectly, you'll have a bad shield and a lot of unwanted interference.
And like many have said, this is easy to get wrong and I'd be surprised if this works like you'd expect.

In regards to the 3 to 2 prong ground lifter, you are now effectively "floating" the wurlitzer signal ground to eliminate the ground loop.
However, not having a connection to actual earth ground may adversely affect noise and interference.
Looking through the schematic nothing stood out as blatantly unsafe if you use a ground lifter, but I wouldn't feel comfortable without an earth ground connection(3prong) so I wouldn't recommend this.