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post #31 of 298
Sclamb, sorry to hear of these issues you are having. FWIW, my WA6 (not SE) is at 220V/50Hz and is dead quiet. I think the WA6SE is quite different though and does exhibit some low level hum from what I have been told. As takezo mentioned, it does seem to occur in some tube amps.
Thanks for the info about the 274B. If you are going to try a different rectifier, any NOS American RCA, JAN, Sylvannia or TungSol 5u4g, 5u4gb, 54rgy or gz34 tubes would be a great tube to try and they are relatively inexpensive. Even cheaper might be to swing past a guitar shop and get a new 5u4g or gz32 or gz34 which some Fender amps use, so they should have plenty in stock.
post #32 of 298
Thread Starter 
Thanks musicmind. Good idea about the guitar shop, I'll see if I can get to one tomorrow. I believe from another poster in this thread that a 5AR4 would also be fine. Hopefully I can find something tomorrow to see if I can narrow the fault down to the tube or otherwise.
post #33 of 298
Quote:
Originally Posted by sclamb View Post
INteresting. Does your amp hum at all?
Nope, no hum.
post #34 of 298
every tube amp i've owned has or had a low level mechanical hum
from the power transformer... it's a low range "drone"-like hum
and should be inaudible from 2 to 3 feet (or 1 meter) away with
the headphone on... if your amp is humming louder than a very soft
whisper then you may have a serious issue with the power transformer,
or the attachment of it to the amp chassis causing oscillation
or vibration... good luck

and yes, all tubes hum to a certain degree... almost no exceptions as
far as i know... some hum louder than others however... using a
tube damper may help a little... any cheap damper should work...
post #35 of 298
Thread Starter 
The hum is low level and is a 'drone' like humming sound. I cannot hear it at all with the headphones on (even with no music playing), and I can hear it faintly up to about three feet away in a quiet room with the headphones off. It certainly is not loud.

I wonder why everyone else with a WA6 or WA6 SE is reporting that their amps are dead quite with no hum at all. Seems odd that mine hums and others don't.

I have Halo-O tubes dampers on all the tubes.

I really hope this is a tube fault though!
post #36 of 298
mine hum too... but barely audible and only when i'm close to the
amp with the music paused... maybe that we're just sensitive
to the frequency...
post #37 of 298
Quote:
Originally Posted by sclamb View Post
I also just noticed this. When I turn on the power, I see a white flash go up the mesh plate on the Sophia tube before it start to glow orange. Is this normal?
No, this is not normal. This will ruin the tube. It is too much current being drawn to fill the first cap. A GZ34 most likely would not do this but the 274B and 5U4G etc are rated for a 4uf first cap or a 15 to 20 henry inductor right after the rectifier.
post #38 of 298
Thread Starter 
Could be sensitivity to that frequency. To be honest, what started out as a thread about the humming sound has turned into 'why is my 274B getting white sparks on start-up?'. If they are related, then perhaps my amp needs to go back to the US for a check-up.
post #39 of 298
Thread Starter 
Quote:
Originally Posted by jamato8 View Post
No, this is not normal. This will ruin the tube. It is too much current being drawn to fill the first cap. A GZ34 most likely would not do this but the 274B and 5U4G etc are rated for a 4uf first cap or a 15 to 20 henry inductor right after the rectifier.
Surely Jack would have the amp set up correctly as he offers the 274B as a rectifier tube upgrade. I have only just seen this white sparking tonight after a couple of weeks of usage. I assume my WA6 SE (I also had the performance parts upgrade so not sure if that has affected things) is the same as everyone else's and they seem to be OK with the 274B tube.
post #40 of 298
yeah, take advantage of the warranty when you still have it...
for peace of mind... i've never noticed a spark on my valvart 274b
nor on the sylvania 274b in the past...
post #41 of 298
Damping of the transformer can cut down on the hum or just the way the transformer is made can cut it down. I have worked with tube amps and preamps and made up circuits for tubes and not all tubes produce audible hum and not all transformers hum. I have a preamp I built with two large transformers and the transformers are totally quiet, even with your ear next to them. The preamp, no hum at all. It is in the way everything is worked, implementation.

Sure a tube can be bad and arc but from what I have read here aren't there two amps doing this? Also a new tube can work fine at first but as it is stressed the arcing can start to show up and it will get worse and worse until the tube fails and normally takes out the fuse do to high current enrush.

Transformers can hum due to DC on the line. Factories with large electrical motors can induce this into the line as well as other current using devices. Bad transformers on the power line can also cause problems. You can also try to reverse the power cord but then you would lose the ground by using a cheater. With sparks dropping on the Sophia it is already toast.
post #42 of 298
Thread Starter 
Thanks jamato8. I guess I need to wait until I hear from Jack and see what he suggests I do. Shipping back to the US will be a pain and expensive.

I will try another tube and see if the hum is reduced or stops, but from what you say I guess another tube won't make much difference. It is sounding like I have a faulty amp.
post #43 of 298
Quote:
Originally Posted by sclamb View Post
Thanks jamato8. I guess I need to wait until I hear from Jack and see what he suggests I do. Shipping back to the US will be a pain and expensive.

I will try another tube and see if the hum is reduced or stops, but from what you say I guess another tube won't make much difference. It is sounding like I have a faulty amp.
It is hard to say for sure. Measuring different voltages etc is what would need to be done.

Did it do this from the beginning? It is always possible that you have a bad tube. I would try an 5U4G or GZ34 and see how the transformer section sounds or doesn't sound.
post #44 of 298
surprising considering the SE has two large inductors between the
rectifier and the first caps... but if one or both have failed somehow,
shouldn't he be hearing humming during the pause or even behind
the music?

oh right... it could just be a faulty rectifier...
post #45 of 298
Thread Starter 
I cannot remember if it hummed from the beginning, but the 274B tube definitely did not have the white spark until today.
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