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Woo Audio Amp Owner Unite
May 25, 2013 at 5:09 PM Post #25,696 of 42,298
Since a week I'm the owner of a used WA3 and now in need of some brainstorming from you guys. Unfortunately the amp hums lightly but too audible coming from the transformer (powered up doing nothing / source unplugged). Bear with me before you say it's normal for tube amps. I've found that the transformer hum vanishes when I unscrew and take off the ''hatch'' which covers the transformer. When I lay back the hatch the hum is back (with or without putting the screws back in). The enclosure looks flawless to me. No obvious problems to be seen. Any ideas what's going on and how to solve this?
 
Second issue is a hum in the right channel over different types of headphones. It's volume independent and already switched the left tube for right. Source unplugged and tried another AC outlet.
How likely is this a tube problem and if so, how can I know if it's the power tube or drivers?
 
May 25, 2013 at 5:35 PM Post #25,697 of 42,298
Do you hear it in the headphones or from the outside of the amplifier?

moriez said:
Since a week I'm the owner of a used WA3 and now in need of some brainstorming from you guys. Unfortunately the amp hums lightly but too audible coming from the transformer (powered up doing nothing / source unplugged). Bear with me before you say it's normal for tube amps. I've found that the transformer hum vanishes when I unscrew and take off the ''hatch'' which covers the transformer. When I lay back the hatch the hum is back (with or without putting the screws back in). The enclosure looks flawless to me. No obvious problems to be seen. Any ideas what's going on and how to solve this?


Second issue is a hum in the right channel over different types of headphones. It's volume independent and already switched the left tube for right. Source unplugged and tried another AC outlet.

How likely is this a tube problem and if so, how can I know if it's the power tube or drivers?
Click to expand...
 
May 25, 2013 at 5:55 PM Post #25,698 of 42,298
The WA3 is capacitor coupled between driver and outputs. You can turn it on with no driver tubes in place to see if the output tube is the one humming. Next question.....does your model have a choke in the power supply or just resistors? The newer ones had chokes and are quieter. You may also want to consult some of the power supply mods in this thread: http://www.head-fi.org/t/94853/woo3-modified/225#post_9269260

moriez said:
Since a week I'm the owner of a used WA3 and now in need of some brainstorming from you guys. Unfortunately the amp hums lightly but too audible coming from the transformer (powered up doing nothing / source unplugged). Bear with me before you say it's normal for tube amps. I've found that the transformer hum vanishes when I unscrew and take off the ''hatch'' which covers the transformer. When I lay back the hatch the hum is back (with or without putting the screws back in). The enclosure looks flawless to me. No obvious problems to be seen. Any ideas what's going on and how to solve this?


Second issue is a hum in the right channel over different types of headphones. It's volume independent and already switched the left tube for right. Source unplugged and tried another AC outlet.

How likely is this a tube problem and if so, how can I know if it's the power tube or drivers?
Click to expand...
 
May 25, 2013 at 6:41 PM Post #25,699 of 42,298
Quote:
mcdanderson said:
I'm so excited... my WA6-SE w/ sophia princess just came in!!! I'm installing the tubes right now. Can't wait to try it!
Click to expand...

 
Installing tubes... and typing... at the same time? Now, that's 
tongue_smile.gif
excitement! Though, you could be using 
rolleyes.gif
 dictation software.
 
CONGRATS! however you're workin' it.
 
May 25, 2013 at 9:16 PM Post #25,703 of 42,298
SO, you have the most epic avatars!
 
beerchug.gif

 
May 26, 2013 at 3:19 AM Post #25,704 of 42,298
talking about rectifiers, has any1 used a U52 tube in a WA6-SE?
 
May 26, 2013 at 3:56 AM Post #25,705 of 42,298
Quote:
grindingthud said:
Do you hear it in the headphones or from the outside of the amplifier?
Click to expand...

 
Both.
 
Quote:
grindingthud said:
The WA3 is capacitor coupled between driver and outputs. You can turn it on with no driver tubes in place to see if the output tube is the one humming. Next question.....does your model have a choke in the power supply or just resistors? The newer ones had chokes and are quieter. You may also want to consult some of the power supply mods in this thread: http://www.head-fi.org/t/94853/woo3-modified/225#post_9269260
Click to expand...

 
I'm happy with your pointers but the manual specifically says DO NOT turn it on without all tubes in it. Are you sure sure? About the choke/resistors, no idea. What do I look for? All I know is that it's build in October/November of 2011.
 
May 26, 2013 at 7:55 AM Post #25,706 of 42,298
Quote:
silent one said:
 
Currently, using only my iPod>HD650 combo. Everything else is in storage. Been on sabbatical for a few years; now returning home any month now. Hopefully June/July and then 
tongue_smile.gif
out comes the audio rig!
 
Basically over 24 moon period: (only a sample, as I do not want to SPAM the thread)
 

 

 

 

 

 

 

 

 
Click to expand...

 
 
Quote:
silent one said:
@ magiccabbage
 
My last Profile Page entry was 20 May 2012 - Sunday, 1545 hours (not updated): 
 
 
 
[size=1em]
Location:
 		 LA (away on sabbatical)
 
Forum Post Count:
 		 3641
 
Last Online:
 		 1 second ago
 
Interests (Hobbies, favorite activities, etc.):
 		 Letters; Cycling; Photography
 
Headphone Inventory
 		 Denon AH-D7000 - XLR (Balanced)
Sennheiser HD 280 pro
Shure E3C's w/Sensaphonics custom ear molds.
Audez'e LCD-2 - XLR (Balanced) On loan... (returned)
HiFiMan HE-5LE - XLR (Balanced) On loan... (returned)
HiFiMan HE-6 XLR (Balanced) On loan... (returned)
HiFiMan HE-6 XLR (Balanced & Hard-wired) Incoming...
Sennheiser HD600 (recabled) On loan... (returned)
AKG K702 (recabled) On loan... (returned)
Beyer DT-990 (600-ohm) On loan... (returned)
 
Headphone Amp Inventory
 		 6AS7 OTL Amp Custom Built by 2359glenn
Woo Audio WA 6 Special Edition SET Class A (sold)

drive tubes -
Tung-Sol 6SN7GT/VT-231 Black Glass Round Plate w/Oval Mica 1940's
Raytheon-USN-CRP 6SN7W 1949
RCA 6SN7GT Grey Glass

power tubes -
Tung-Sol JAN-CTL-5998 1952

rectifier tubes -
United Electronics Company USAF-596 1957
United Electronics Company USAF-596 1956
General Electric 3DG4
Emission Labs 5U4G Mesh Plate (gifted)
 
Source Inventory
 		 2010 Mac mini, Corsair 60GB SSD, 8GB RAM; Amarra; Pure Music; Audirvana
2011 Lenova Notebook; Lubuntu/LXDE; MPD/GMPC; Audacious
2012 Logitech Squeezebox Touch (Returned))
 
Cable Inventory
 		 WireWorld Headphone Cable
Zeus Quad22 OCC Copper 4x22 AWG - XLR (Balanced w/matching adapter) 


WireWorld Power Conditioning Cords 
Electra 5* OCC Copper w/Furutech 24k Gold connectors (Music server)
Electra 5* OCC Copper w/Furutech 24k Gold connectors (DAC)
Electra 5* OCC Copper w/Furutech 24k Gold connectors (Amp)


WireWorld Digital Audio Interconnect 
Silver Starlight 6 OCC Silver-Clad Copper 


WireWorld USB Digital Audio Cable
Silver Starlight 6 OFC Silver-Clad Copper


WireWorld Analogue Audio Interconnect 
Eclipse 6 OCC Copper + Silver Tube plugs 
Equinox 6 OCC Copper + ViaBlue 1/4 Mono plugs & Silver Tube RCA plugs
 
Power-Related Components
 		 APC AV H Type Power Conditioner H10 1000 VA
Monster Power Pro 2500 PowerCenter; Stage 2 v2.1 Filtering (Gone)
 
Other Audio Equipment
 		 Wyred4Sound DAC-1 w/Low ESR "Super Caps"
Mhdt Havana DAC Balanced Version - On loan... (returned)
Mhdt USBridge
Violetric V800 DAC - On loan... (returned)
EMU-0404 USB 2.0 w/Regal linear power supply
Pioneer SX-650 Integrated Receiver Vintage 1977
Gemini PT-2000 III TT/ Shure Whitelabel Cartridge 
Sony TCD-D8 Portable DAT Recorder
Sony Walkman Professional
 
Audio-Related Tweaks
 		 ViaBlue TRI Absorbers (Music server; DAC)
Dayton Audio DSS4-BK Black Speaker Spikes (Amp)
Maple Isolation Platforms - 15 x 12 x 4 & 17.5 x 16 x 2
Black Isoblocks - 2"
 
Music Preferences
 		 Jazz; Soul; R&B; Blues; World (African; Caribbean; Brazilian; Latin; Chinese; Indian; Middle Eastern ect); Zydeco; Classical and more...
 
Interests (non-headphone)
 		 Food; Music; Sports; Culture
 
Gear-Fi (Favorite Non-Audio Gear & Gadgets)
 		 Gaiwans; Road bike; Rhodia Notepads; Fountain pens
[/size]
Click to expand...

 
 
 
 
I actually remember some of those images now from a while back i just couldn't remember that they they were yours. You must have a lot of friends into hi-fi to get all that gear on loan. Are the wood blocks a microphonics thing? I love the look of the sansui but i never listen to the radio so i couldn't justify getting one. I would love to get a preamp that has the same look and finish as those old receivers though.
 
May 26, 2013 at 8:14 AM Post #25,707 of 42,298
The big gold transformer looking thing inside is the choke. Attached a photo. For the WA3, I've never had a problem running with the drivers out....and the circuit design supports it ok. For the external transformer noise, you can try tightening the retaining nut inside the transformer box or putting a bit of stiff padding under the round plate that holds the transformer and tightening down on that. That being said, getting a perfectly quiet 6AS7 type can be a bit of trial and error. The Tung Sol 6080WA tends to be a very quiet tube that is not expensive compared to many. Hum in drivers is pretty common. I find most 6DJ8 types are pretty quiet. Many have been particularly happy with Brimar 6DJ8. I like Holland A frames.


moriez said:
About the choke/resistors, no idea. What do I look for? All I know is that it's build in October/November of 2011.
Click to expand...
 
May 26, 2013 at 8:22 AM Post #25,708 of 42,298
Sorry about the clog up guys i meant to quote just the txt and not the images.
 
 
May 26, 2013 at 9:07 AM Post #25,709 of 42,298
@GrindingThud,
 
Wonderful. I will open it up and see what can be done. Are there any dangerous areas I should stay away from? Jack Woo also suggested to tighten or loosen the bold but that didn't do it.

As for the headphones right channel issue: I took out the drivers and still the hum is present.
 
May 26, 2013 at 9:37 AM Post #25,710 of 42,298
Unplug the amp before peeking inside. You will see bare solder joints and leads of resistors and capacitors and tube socket pins. To be safe if you are not familiar with electronics, just don't touch them.....but after 30 seconds of being turned off everything inside is discharged anyway, so the risk is very low.

Sounds like your output tube is humming....pretty common. Get a new one.

moriez said:
@GrindingThud,

Wonderful. I will open it up and see what can be done. Are there any dangerous areas I should stay away from? Jack Woo also suggested to tighten or loosen the bold but that didn't do it.


As for the headphones right channel issue: I took out the drivers and still the hum is present.
Click to expand...
 
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