[pippen99]

$750 is incredibly cheap for a new pair of KR 2A3. KR makes two varieties of 2A3. The HP with a white base and a regular with a black base. Make sure the new pair matches the pair you have on hand.

 

[musicinmymind]

$750 is incredibly cheap for a new pair of KR 2A3. KR makes two varieties of 2A3. The HP with a white base and a regular with a black base. Make sure the new pair matches the pair you have on hand.

Thanks for let me know, I have four white base so it should be HP.
if I peak inside when it's on, I can see three of them glow and one doesn't. Should I replace with matched pair or just the one that is broken?

 

[pippen99]

I think tube matching is probably overrated. If you can find someone to sell you a single that is how I would go.

 

[trekker140]

Hello fellow Woo owners/enthusiasts! I am a new owner of a WA5-LE with the premium parts upgrade, and while I am generally delighted with the performance and sound of the amp, I do have a few questions as I am new to the world of high powered tube amps.

Firstly, what level of hiss is considered normal? There is a moderate level hiss in the right channel that is present on all of the headphones I own, both high impedance/low sensitivity and all the other permutations of such. The hiss increases in volume when switching on high impedance mode, and further increases on high power mode. I can’t hear it when music is playing, but I am used to solid state amps that are inky black in their background. For reference, I am using new production Western Electric 300B power tubes, Sophia Electric Aqua 274B rectifiers, and RCA NOS ”brown base” drive tubes.

Second, I have a buzz that sounds like some sort of grounding issue. It’s present in both channels, and remains at a constant level no matter what settings are applied. It is more noticeable on high sensitivity headphones. Might a power conditioner/transformer isolator be a good fix for this?

I’ve emailed Woo with these questions, but I wanted to see what you all think about these issues.

 

[ColSaulTigh]

Hello fellow Woo owners/enthusiasts! I am a new owner of a WA5-LE with the premium parts upgrade, and while I am generally delighted with the performance and sound of the amp, I do have a few questions as I am new to the world of high powered tube amps.

Firstly, what level of hiss is considered normal? There is a moderate level hiss in the right channel that is present on all of the headphones I own, both high impedance/low sensitivity and all the other permutations of such. The hiss increases in volume when switching on high impedance mode, and further increases on high power mode. I can’t hear it when music is playing, but I am used to solid state amps that are inky black in their background. For reference, I am using new production Western Electric 300B power tubes, Sophia Electric Aqua 274B rectifiers, and RCA NOS ”brown base” drive tubes.

Second, I have a buzz that sounds like some sort of grounding issue. It’s present in both channels, and remains at a constant level no matter what settings are applied. It is more noticeable on high sensitivity headphones. Might a power conditioner/transformer isolator be a good fix for this?

I’ve emailed Woo with these questions, but I wanted to see what you all think about these issues.

Welcome to the "Woo Crew"!!!

I'll take these in reverse order. Hum/Buzz issues are almost always either a ground/impedance mismatch issue in your system or phantom DC coming from your AC lines. If you're not using any kind of "surge protector" product, I highly recommend one with DC blocking. I personally use THESE and they work perfectly. My amp is dead quiet.

Regarding the hiss, start with the driver tubes and work your way back. I have some RCAs which perform fine, but you can get the occasional noisy pair. With the WA5, you hear everything in the tube chain. You can always try reflowing the solder in the pins on those tubes, which can help quiet noisy tubes (video on how to do this HERE.) As a simple test, pick up another cheap pair online or at your local Guitar Center (or other guitar amp retail store) and see if the hiss changes. The Sophia Aqua 274Bs are not likely to cause the hiss, nor are the WE300B's.

If you haven't read this in the manual yet, ***WARNING - DO NOT FLIP THE "HI POWER" SWITCH ON OR OFF WITH HEADPHONES PLUGGED IN AND/OR THE UNIT TURNED ON!!*** This will produce a headphone-damaging "POP!" which can not only destroy your headphones but can also cause hearing damage.

You will get some hiss when you have the impedance or level settings set too high on sensitive headphones. Having said that, I run mine at full power, high level, and only adjust impedance based on the headphones I'm listening to at the moment. I will get some minor hiss on very sensitive headphones (Meze Elite come to mind), but nothing distracting at all. At a 12:00 level or lower, you should be dead quiet.

Final thought - if you're using RCA cables to connect source gear, those can also introduce hum into the system. It's for that reason I almost exclusively use XLR (which isn't without it's own problems). Feel free to ask any additional questions, we're here to help!

 

[SteveHulk]

Hello fellow Woo owners/enthusiasts! I am a new owner of a WA5-LE with the premium parts upgrade, and while I am generally delighted with the performance and sound of the amp, I do have a few questions as I am new to the world of high powered tube amps.

Firstly, what level of hiss is considered normal? There is a moderate level hiss in the right channel that is present on all of the headphones I own, both high impedance/low sensitivity and all the other permutations of such. The hiss increases in volume when switching on high impedance mode, and further increases on high power mode. I can’t hear it when music is playing, but I am used to solid state amps that are inky black in their background. For reference, I am using new production Western Electric 300B power tubes, Sophia Electric Aqua 274B rectifiers, and RCA NOS ”brown base” drive tubes.

Second, I have a buzz that sounds like some sort of grounding issue. It’s present in both channels, and remains at a constant level no matter what settings are applied. It is more noticeable on high sensitivity headphones. Might a power conditioner/transformer isolator be a good fix for this?

I’ve emailed Woo with these questions, but I wanted to see what you all think about these issues.

Is it a buzz (very nasty edgy sound) or a (smooth) hum?

If it is a buzz you would need to get onto Woo about that.

If it is a hum have you tried adjusting the trimpots (aka "humdinger" or "humbucker" pots) located under each handle of the amp section?

They can be adjusted (awkwardly) with a small screwdriver. The maximum range of rotation is just over half a turn end to end. Hopefully you can find an adjustment near the middle which reduces or eliminates the hum completely.

As to the hiss...

Firstly, are you sure your source device is silent? A high-quality source device should be completely silent.

If it is then switch your attention to the 6SN7 tubes.

These tubes have indirectly heated cathodes. This means that the cathode is a small pipe with an oxide-coated heater filament inserted. The oxide coating provides the insulation between the heater and the cathodes. The two triodes in the 6SN7 envelope share the same heater filament.

However, the two cathodes in the WA5-LE setup are at rather different voltages above ground. This places a quite heavy burden on the heater insulation.

As far as I can tell, Woo have left the heater more or less at ground potential and have not even split the difference between the cathode potentials to ease the electrostatic stress on the heater insulation.

Leakage current from the heater to the cathodes will cause hiss as this current is effectively an electrostatic discharge through the insulation.

The only fix for this is to find (and hang on to) a pair of 6SN7 that have good heater to cathode insulation.

With a good pair of 6SN7 your amp should have no discernable hiss.

 

[trekker140]

Welcome to the "Woo Crew"!!!

I'll take these in reverse order. Hum/Buzz issues are almost always either a ground/impedance mismatch issue in your system or phantom DC coming from your AC lines. If you're not using any kind of "surge protector" product, I highly recommend one with DC blocking. I personally use THESE and they work perfectly. My amp is dead quiet.

Regarding the hiss, start with the driver tubes and work your way back. I have some RCAs which perform fine, but you can get the occasional noisy pair. With the WA5, you hear everything in the tube chain. You can always try reflowing the solder in the pins on those tubes, which can help quiet noisy tubes (video on how to do this HERE.) As a simple test, pick up another cheap pair online or at your local Guitar Center (or other guitar amp retail store) and see if the hiss changes. The Sophia Aqua 274Bs are not likely to cause the hiss, nor are the WE300B's.

If you haven't read this in the manual yet, ***WARNING - DO NOT FLIP THE "HI POWER" SWITCH ON OR OFF WITH HEADPHONES PLUGGED IN AND/OR THE UNIT TURNED ON!!*** This will produce a headphone-damaging "POP!" which can not only destroy your headphones but can also cause hearing damage.

You will get some hiss when you have the impedance or level settings set too high on sensitive headphones. Having said that, I run mine at full power, high level, and only adjust impedance based on the headphones I'm listening to at the moment. I will get some minor hiss on very sensitive headphones (Meze Elite come to mind), but nothing distracting at all. At a 12:00 level or lower, you should be dead quiet.

Final thought - if you're using RCA cables to connect source gear, those can also introduce hum into the system. It's for that reason I almost exclusively use XLR (which isn't without it's own problems). Feel free to ask any additional questions, we're here to help!

Thank you for the welcome! I’ve been wanting a Woo product for quite some time and am glad I finally took the leap.

I will try your suggested DC blocking equipment and see if that helps. I also bought a better shielded power cable as the amp is close to my computer.

As far as the hiss goes, I will try using the stock tubes that came with the amp instead of the RCAs to see if that makes a difference. I will be able to test this out this evening.

And good to know regarding the power switch! I will be very careful with it as I would weep if I cooked any of my headphones.

Thanks a bunch for your suggestions!

 

[ColSaulTigh]

Thank you for the welcome! I’ve been wanting a Woo product for quite some time and am glad I finally took the leap.

I will try your suggested DC blocking equipment and see if that helps. I also bought a better shielded power cable as the amp is close to my computer.

As far as the hiss goes, I will try using the stock tubes that came with the amp instead of the RCAs to see if that makes a difference. I will be able to test this out this evening.

And good to know regarding the power switch! I will be very careful with it as I would weep if I cooked any of my headphones.

Thanks a bunch for your suggestions!

Ooooh - PC's are notorious for creating all sorts of noises in the system. Are you running USB to a DAC perchance? If so, try using a powered USB hub (one that requires a wall-wart, not powered by USB) in between the PC and DAC. That should also help.

 

[trekker140]

Is it a buzz (very nasty edgy sound) or a (smooth) hum?

If it is a buzz you would need to get onto Woo about that.

If it is a hum have you tried adjusting the trimpots (aka "humdinger" or "humbucker" pots) located under each handle of the amp section?

They can be adjusted (awkwardly) with a small screwdriver. The maximum range of rotation is just over half a turn end to end. Hopefully you can find an adjustment near the middle which reduces or eliminates the hum completely.

As to the hiss...

Firstly, are you sure your source device is silent? A high-quality source device should be completely silent.

If it is then switch your attention to the 6SN7 tubes.

These tubes have a indirectly heated cathodes. This means that the cathode is a small pipe with an oxide-coated heater filament inserted. The oxide coating provides the insulation between the heater and the cathodes. The two triodes in the 6SN7 envelope share the same heater filament.

However, the two cathodes in the WA5-LE setup are at rather different voltages above ground. This places a quite heavy burden on the heater insulation.

As far as I can tell, Woo have left the heater more or less at ground potential and have not even split the difference between the cathode potentials to ease the electrostatic stress on the heater insulation.

Leakage current from the heater to the cathodes will cause hiss as this current is effectively an electrostatic discharge through the insulation.

The only fix for this is to find (and hang on to) a pair of 6SN7 that have good heater to cathode insulation.

With a good pair of 6SN7 your amp should have no discernable hiss.

I will listen closely this evening to hear exactly what kind of noise it is. I think it‘s closer to a buzz than a hum, but it isn’t super loud. I will ask Woo’s people about that. I will also try adjusting the trim pots to see if that makes a difference.

The source is a Burson Timekeeper 3i which has never made any kind of noise. It’s connected to my computer with a good quality USB cable, and then again from the pre-out on the Burson to the RCA on the Woo. I do have some XLR cables lying around and will try those.

I will also do some research on 6SN7s. I would hate to send the RCAs back, as I am otherwise quite pleased with their sound.

Thanks very much for the reply!

 

[trekker140]

Ooooh - PC's are notorious for creating all sorts of noises in the system. Are you running USB to a DAC perchance? If so, try using a powered USB hub (one that requires a wall-wart, not powered by USB) in between the PC and DAC. That should also help.

I will give that a try. Yes, I’m running from my PC to a DAC (Burson Timekeeper 3i) via USB-C and then to my Woo via RCA.

 

[mab1376]

Hello fellow Woo owners/enthusiasts! I am a new owner of a WA5-LE with the premium parts upgrade, and while I am generally delighted with the performance and sound of the amp, I do have a few questions as I am new to the world of high powered tube amps.

Firstly, what level of hiss is considered normal? There is a moderate level hiss in the right channel that is present on all of the headphones I own, both high impedance/low sensitivity and all the other permutations of such. The hiss increases in volume when switching on high impedance mode, and further increases on high power mode. I can’t hear it when music is playing, but I am used to solid state amps that are inky black in their background. For reference, I am using new production Western Electric 300B power tubes, Sophia Electric Aqua 274B rectifiers, and RCA NOS ”brown base” drive tubes.

Second, I have a buzz that sounds like some sort of grounding issue. It’s present in both channels, and remains at a constant level no matter what settings are applied. It is more noticeable on high sensitivity headphones. Might a power conditioner/transformer isolator be a good fix for this?

I’ve emailed Woo with these questions, but I wanted to see what you all think about these issues.

Try this for the high channel hiss:

https://static1.squarespace.com/sta...cbbc126b6/1521133798858/WA5_Owners_Manual.pdf

 

[magiccabbage]

Hey guys

I just bought a hifiman Arya v2 which I will primarily use with a Ragnarok 2 but I will also try it with my wa5. I have the original with the K1000 port. I don't have a high low power switch just high low for impedance

I'm wondering if it's possible to get a cable for the Arya that uses the k1000 port. Does anyone know?

Also has anyone tried the Arya here with wa5.?

Edit.... The k1k port is a normal balanced input actually. I have never used it before. I'm assuming I use the hi low impedance with this input as I would with the single ended. So low impedance for the Arya's?


Sorry for the convoluted questions. Been a while since I was on these forums

 

[mab1376]

Taking the WA22 out for a spin with my HE-500 this morning.

TS 5998, TS 6F8G, Sophia 274B mesh

 

[MRHiFiReviews]

Woo Audio WA2 OTL Headphone Tube Amplifier Sennheiser High Impedance Headphones best friend!

 

[trekker140]

Thank you to everyone who had very helpful and informative tips for my new WA5's hiss and buzz issue. I am delighted to say that both issues are almost completely resolved. The buzz went away after installing a good quality Moon Audio power cable and a Tripp Lite isolation transformer. The hiss has faded to be almost completely inaudible on every pair of headphones I own except my IEMs, which is perfectly normal. Also, the hiss no longer increases in volume when I advance the volume knob. It's very quiet even when the volume is maxed out. I do still get a little hiss on high impedance mode, but it seems to be growing fainter and fainter by the hour. Who knows. I am now 100% satisfied with my Woo. I think I've reached my endgame (at least for now!). Last night, while relaxing with a nice Maker's Mark, listening to Eric Clapton's Riding with the King on my Dan Clark Audio Expanses had to be the single best audio experience of my life. Wow.