[j5brock]

I got this thinking it would warm up my W5000s a tad.. But WOW - I plugged in the HD650s and they sound like new headphones - bright but detailed with great lows.. not that the W5000s don't sound good - but the difference between the Grace M902 with the HD650's and the Woo6 with 650s is unbelievable.. perhaps with a Mullard NOS 5U4G I will find the real warmth I am looking to add to the W5000s.. Anyway - very impressed with the Woo6.

Jeff

 

[phaseshift]

Jeff, My Woo 6 should be coming Monday. Sounds like ours were built a day apart. I'll be driving AKG K701's. Can't wait to get it. Are you happy with the build construction? Do you get any hum at all? Does it have enough drive on low impedance headphones? I'm wondering what the 6ed7 tubes can be substituted with? Let me know all about it. Waiting till Monday, perhaps Tuesday is just killing me. Got any pics?

 

[Tech2]

I didn't know that Mullard made a 5U4G, maybe a GZ37?...or a Mullard 5AR4?

Regardless, I also recently got a Woo6 and have been running it with various rectifier tubes. Tube purchases can add up quickly. I have spent a few bucks on tubes over the past few weeks including a Philips Miniwatt 5AR4 and a Japanese 5AR4. I also have several 5U4Gs (JAN RCA, Raytheon, GE). I also have purchased several pairs of driver tubes (Amperex, RCA, GE, Dumont). This in addition to the Chinese 5AR4 and Svetlana 5U4G that I got with the amp. In total, I have 6 pairs of 6DE7s, 6 5U4G 'coke bottles', 1 RCA 5U4GB, and 3 5AR4s. That's a lot of potential combinations to try.

And this is a meager collection compared to what I've seen here on the forums.

I will say this:

When I first got the amp I listened with my HD600 for the first few days and it sounded wonderful (still does). I've been listening mainly with the Raytheon rectifier and the GE driver tubes. Then I got out my 325i, and haven't looked back. The Woo6 seems to warm them up nicely, at least compared to the only solid state amp I've used with them (Gilmore Lite, which I sold).

The Woo amp is a great amp with exceptional build quality. I've definitely become a fanboy.

 

[GreatDane]

I demand pics

Enjoy

 

[j5brock]

Your right about the Mullard - actually have a Bugle Boy 5AR4 on the way to try with the W5000s.. I will post some pics late tomorrow or Sunday - as I am at our lakehouse - previous commitment keeps me from the new toy.. Build quality seems great - had a little problem getting the 5AR4 to seat correctly - once in - completely black with no source... No buzz at all.

 

[Tech2]

I had the same problem when I initially changed the rectifier tube. It resisted a bit, but now I think the socket pins have loosened up a bit and the tubes pop right in and out.

As for hum/buzz, I initially had none with my HD650, but I did detect a very slight buzz with my 325i. I lopped the ground pin off of my el-cheapo computer-grade power cord and it's gone. Must have been 60hz interference or ground loop. I think my next purchase might be a power cord with a removable ground pin. I don't usually go in for expensive interconnects and power cords, but I've seen a 1-meter PS Audio XStream Super Punch power cord which has a removable ground for $35. I can live with that.

 

[phaseshift]

Do you get any buzz or hum with a source plugged in? Please tell me no.

 

[Tech2]

Yes, I had a very minor buzz that I couldn't detect with my HD600. I could only hear it with my 325i. I tried swapping out some tubes but it didn't go away, so I cut the ground pin off of my power cord and it disappeared. I haven't heard it since.

 

[phaseshift]

I thought running with no ground was a bad thing? Are you saying you had a ground loop then?

 

[sacd lover]

Quote:

Originally Posted by Tech2 /img/forum/go_quote.gif Yes, I had a very minor buzz that I couldn't detect with my HD600. I could only hear it with my 325i. I tried swapping out some tubes but it didn't go away, so I cut the ground pin off of my power cord and it disappeared. I haven't heard it since.

I would be very careful about lifting the ground on a tube amp. You could have a shocking experience.

 

[Tech2]

Quote:

Originally Posted by phaseshift /img/forum/go_quote.gif I thought running with no ground was a bad thing? Are you saying you had a ground loop then?

It's possible.

I didn't know what might be causing the buzz, so I searched google and found some info on ground loops, which may cause a 60hz hum or buzz. The remedy in many cases was to remove the ground pin, which has seemed to work for me. Whether or not it's merely a coincidence, I don't know. All I know is that the buzz is gone.

As far as whether or not it's safe, I imagine it shouldn't be a major problem since I'm not sitting in water or being rained on while I listen. Seriously, I don't think it's dangerous. As I posted above, some of the 'better' power cords have a removable ground pin that unscrews from the plug for this very purpose. I used a hacksaw blade on mine.

Edit - I will say this: I suppose that the amp may have had a component that was causing the buzz, and that it has settled in and stopped. I don't know for sure, so I intend to try it again with a grounded cord to see what happens and then I'll know for certain if that was the cause. I'm not advocating that anyone use a cord without a ground, I'm merely stating my experience.

 

[Tech2]

Quote:

Originally Posted by sacd lover /img/forum/go_quote.gif I would be very careful about lifting the ground on a tube amp. You could have a shocking experience.

Well, apparently it can be dangerous, but so far I've suffered no ill effects such as headphone-electro-shock-therapy. Hopefully I won't.

 

[phaseshift]

Has anyone else had hum or buzz with Woo amps? This is very discouraging.

 

[GreatDane]

Quote:

Originally Posted by Tech2 /img/forum/go_quote.gif I tried swapping out some tubes but it didn't go away, so I cut the ground pin off of my power cord and it disappeared.

I hope it wasn't an expensive cord. I keep cheater plugs handy:

I've never heard any hum with my WA3.

 

[Tech2]

Quote:

Originally Posted by phaseshift /img/forum/go_quote.gif Has anyone else had hum or buzz with Woo amps? This is very discouraging.

I wouldn't get bummed out about it. I think it's an isolated incident with my set-up. It could have been anything really, and now it's completely gone. I was disappointed when I heard it, but I haven't heard anything for the last couple of weeks, and believe me I'm listening for it now. It's completely gone. If you'd like, I'll plug in a grounded cord and have a listen right now and report back with my result.

Really, give the amp a chance. Jack has a reputation for building a very nice amp, and nobody that I know of has had any type of background noise, at least in the threads that I've read here. I'm certain yours will be fine. I'd bet on it.