[radarnyc]

Does anyone have any experience or impressions of JWN tube amps?

http://jwnamplifiers.vpweb.com/default.html

[kgcdc]

There's a nice review in December's PFO.

He's building mine right now. Been great to work with so far.

Very well-regarded on Audiogon.

[skriefal]

I'm listening to mine right now.  It's a push-pull design using two rectifier tubes (5AR4 or 5U4GB), four output tubes (6L6GC or EL34), two 12AU7 phase inverters, and one 6SN7 driver tube.  Built on a Baldwin organ chassis with massive power transformer, huge choke, and output transformers from a Rowe jukebox (IIRC).  Each output tube is independently cathode-biased, as are all of his amps I believe.  Makes swapping tubes very easy.

I current have a quad of Electro-Harmonix 6CA7 power tubes installed, plus RCA(?) cleartop 12AU7s, and Sylvania 6SN7.  It's a great sounding amp.

What is PFO?  I don't recognize that.  (Acronyms have never been one of my favorite things...)

[Mortsnets]

What is PFO?  I don't recognize that.  (Acronyms have never been one of my favorite things...)

Positive Feedback Online

Lynn Olson has an article on JWN which refers to and earlier article by Dick Olsher.
http://www.positive-feedback.com/Issue58/jwn.htm
http://www.enjoythemusic.com/magazine/equipment/1010/master_builder.htm

[santacore]

I currently own a JWN amp and have been very impressed by it. Both build quality and sonics are excellent. His communication has always been prompt and helpful. The only negative I could find was that the packing was adequate, but not excellent. Thankfully my amp arrived without issue.

[Alexdad54]

I'm currently having an amp built by Jim as well right here here in Philly  and designed to drive my Salk Song Towers with a projected rating of about  50w/channel. He's building it around KT88 / 6550 / or KT90 power tubes and 3 6SN7 drivers.

Can anyone give me some suggestions on the best brands and sources for these tubes?

I've done some researching but must confess to being pretty lost in all the opinions so I thought I'd ask here as I always get great info from AC members.

[jackman]

I'm currently having an amp built by Jim as well right here here in Philly  and designed to drive my Salk Song Towers with a projected rating of about  50w/channel. He's building it around KT88 / 6550 / or KT90 power tubes and 3 6SN7 drivers.

Can anyone give me some suggestions on the best brands and sources for these tubes?

I've done some researching but must confess to being pretty lost in all the opinions so I thought I'd ask here as I always get great info from AC members.

Google Jim McShane.  He's a good guy and he sells new and NOS tubes.  I've bought lots of stuff from him over the years and he is fair with great customer service.

[ken]

I'm currently having an amp built by Jim as well right here here in Philly  and designed to drive my Salk Song Towers with a projected rating of about  50w/channel. He's building it around KT88 / 6550 / or KT90 power tubes and 3 6SN7 drivers.

Can anyone give me some suggestions on the best brands and sources for these tubes?

I've done some researching but must confess to being pretty lost in all the opinions so I thought I'd ask here as I always get great info from AC members.

Sounds like he's building for you the identical amp he built for me.  You're gonna love it   Don't be fooled by the 50 wpc rating  This  amp has some serious power.  I'm currently using Genelex Kt 66 tubes and they sound great.  The el34's I tried weren't that good a quality buts still sounded excellent as well,  Just not as good as the KT66 though. 
  Jim says these are excellent tubes and said he would install them for me as well.  If your amp is still being built I would definitely buy these now and have them shipped to Jim.  Great price as well
http://www.vacuumtubes.com/6BG6.html

[skriefal]

Those are 6L6GC equivalents (as are your KT-66s), which won't give the same output as a 6550 or KT-88.  Probably closer to 30 watts/channel.  Still should be great tubes, though, if the reduced output is okay and you don't mind building the plate cap adapters needed to use them in your amp.

[ken]

I'm using the Kt66 tubes because it's all I currently have at the moment but I do believe the amp is optimized more for Kt6550 - Kt88 tubes although all are supposed to sound very good.  If all I'm getting is 30 wpc with the KT66's it's definitely the most powerful 30 watts I've heard.  I am anxious to try some good Kt88's like the Pentas as well as those 6l6 tubes.  Should be fun.

[Alexdad54]

So based on the input here and some further reading it seems to come down to either the Penta KT88SC or the Shuguang Black treasures. I gather that the latter usually runs about twice the price of the Pentas but I saw some on fleabay for about the same as the Pentas from Dougstubes.com.

Would this be a reliable source?:
http://www.ebay.com/itm/1-Matched-Quad-ShuGuang-50years-TREASURE-Tubes-KT88-Z-/230606628836?pt=LH_DefaultDomain_0&hash=item35b139e7e4#ht_1103wt_1163

I'm not really keen on buying a quad of tubes (the treasures) that cost more than a third of the price of the amp itself.....

Also gotta get a pair of good 6SN7's.....