[realmassy]

And actually it is the other way around, at least for impedance match: OTLs sound better with high impedance cans

 

[avsBuddy]

Actually Tube amps, in general, like high impedance loads (cans, speakers). That's because Tubes can provide high voltage but not a lot of current. On the other hand, solid state can push a lot of current, but not a lot of voltage, thus they have no problem driving lower Ohm loads.
V = I*R (where I = current and R = impedance).
 
That's why, I assume, WA6 drives a broader range of loads  - from low to high impedance cans - it has Transformer to deliver power, just like solid state amps do.

 

[skeptic]

Quote:

Interesting, Skeptic.
I've heard just an opposite when it comes to tube OTL amps vs OT coupled amp. I was told that transformer coupled is exactly what makes amps like WA6 sound more solid state vs pure tube powered design of output transformerless design.

I've seen contradictory statements posted on the topic.  But from the limited comparative listening I've done at meets, among the Woo Audio lineup for example, the OTL options (WA2 and 3) sounded less "tubey" to me than the WA6/WA22, for example.
 
My perception is reinforced by at least a couple of head-fi posts - see post no. 2 in: http://www.head-fi.org/forum/thread/320731/tubey-tube-amp and post no. 1 in http://www.head-fi.org/forum/thread/239029/woo6-versus-doge-6210-shootout
 
(See also the comment by "Dr. Toobz" comparing the OTL "crack" amp kit to bottlehead's alternative transformer-coupled "s.e.x." kit, at http://www.bottlehead.com/store.php?crn=44&rn=442&action=show_detail)
 
I'd definitely be interested to see/hear about your source for the opposite proposition though.  I've yet to read any technical paper nailing this down completely.   
 
Edit - also, you seem to be operating under the impression that most solid state amps use output transformers.  I have no personal knowledge on this issue, but in the thread cited by Golden Monkey on page one, Uncle Erik comments: "As a side note, solid state tends to have a good low output impedance, which is why you almost never see a solid state amp with output transformers."  See: http://www.head-fi.org/forum/thread/388373/can-someone-explain-what-otl-means

 

[Golden Monkey]

I think there's a little confusion here regarding transformers...yes, SS amps have them...they are power transformers (they take AC and transform it to DC). Any amp has a power transformer.  Output transformers (as in, Output Transformerless or OTL), provide output impedance matching (high impedance tube amplification to relatively low speaker/headphone impedance). Uncle Erik's statement "solid state tends to have a good low output impedance, which is why you almost never see a solid state amp with output transformers   "psidfgjnvopewi 

 

[Golden Monkey]

I think there's a little confusion here regarding transformers...yes, SS amps have them...they are power transformers (they take AC and transform it to DC). Any amp has a power transformer, usually a torroidal transformer.  Output transformers (as in, Output Coupled or Output Transformerless aka OTL), provide output impedance matching (high impedance tube amplification to relatively low speaker/headphone impedance). Uncle Erik's statement "solid state tends to have a good low output impedance, which is why you almost never see a solid state amp with output transformers ." is accurate and vaild.

 

[nikongod]

You seldom see SS amps with output transformers because output transformers cost more money than high current SS transistors and a high current power supply. It has very little to do with output impedance - you can get very low output impedances using either method.

 

[skeptic]

Quote:

You seldom see SS amps with output transformers because output transformers cost more money than high current SS transistors and a high current power supply. It has very little to do with output impedance - you can get very low output impedances using either method.

Thanks for the clarification!

 

[regal]

Quote:

You seldom see SS amps with output transformers because output transformers cost more money than high current SS transistors and a high current power supply. It has very little to do with output impedance - you can get very low output impedances using either method.

But when you compare distortion figures and bandwidth it only makes sense for the SS amps to use high current transitors instead of output transformers. 
It is tough for any headphone output transformer to get a very low output impedance,  one simple reason is the secondary DCR of headphone impedance windings. On paper output transformers make little sense to use in any headphone amp:  they cost more, have more distortion, less bandwidth, and higher output impedance than output BJT transistors.   Yet we still use them,  probably because there is some unknown factor at play?
 

 

[Uncle Erik]

Some of the early McIntosh solid state power amps have output transformers.  I especially like the MC2100 because they built it on a tube amp chassis.  It doesn't light up, but still, a very cool old amp.  If I recall, AudioXpress ran a nice article some years back about restoring the MC2100.  I've always wanted to pick one up, but I don't have any use for one.  Though I'd probably cave if I come across one at a good price that needs some TLC.

 

[LAmitchell]

Hey avsbuddy, I heard the same thing you did.  
 
now i don't know what to believe!

 

[Uncle Erik]

Quote:

Hey avsbuddy, I heard the same thing you did.  
 
now i don't know what to believe!

Take a look around AMB Labs since he has a lot of solid state amp projects.
 
Read the parts lists and you won't see a single output transformer.
 
You won't find them anywhere else, except for the early McIntosh power amps and a handful of early transistor designs from 40+ years ago.

 

[Zebra]

I recently read a review in Tone where the reviewer powered a pair of Rethm speakers from the headphone output of a WA3 and was pleased with the result.  Does anyone know if the WA6 or WA6SE would be able to perform the same task?

 

[Vansen]

I'm in the same boat as LAmitchell, I recently purchased a pair of HD650s and am looking for an amp to pair with them. These are the first full sized headphones of any merit that I have owned. I own a few decent IEMs though, such as UE triple.fi 10 and ER-6i. 
 
I wanted to go the tube route rather than SS for an amp. After trolling through these forums for countless hours, I've decided that I want to get a WA3, seems there is some good synergy there with my headphones. I do plan to do a little tube rolling in the future, and I noticed that there is a option on the Woo Audio site to upgrade the tube sockets for $75. Is this something I want to get with my amp, or should I pass on it?

 

[avsBuddy]

I was wondering about the Teflon tube socket upgrade as well. There doesn't seem to be consensus on whether they improve anything. Some people go as far as claiming that Teflon sockets are actually worse because they can deform because of the heat. Woo advertises their superiority over stock because of their gold plated connectors. Can anyone post picture of the stock sockets on Woo amps? How is their quality?

 

[nikongod]

Im not sure if Teflon tube sockets improve SQ, but swapping tubes in an amp with teflon sockets & tulip pins is a positive joy compared to ceramic sockets. IMO this alone makes its worth it. It took me several years of owning amps with only ceramic sockets and 30 minutes with an amp with teflon to adequately appreciate it.
 
Regarding the deformation of teflon sockets, they dont.
Ceramic sockets can shatter, they dont. 
If you can afford the extra expense, DO IT!