Anybody run Tung Sol 6550 in their Eiclone?

a DIY, modified Mullard 5-20 monoblock design

Anybody run Tung Sol 6550 in their Eiclone?

Postby justmikey » Sat Jul 28, 2012 8:11 am

I am just finishing up my new Eiclones and its time to get a quad of decent tubes. I have the rev B boards with 485V B+, fixed bias version, with Edcor 380-0-380 PTs and 4.3K-8 OPTs. I am considering ordering a set of the new production Tung Sol 6550s. Anybody out there use them in an Eiclone? The other option would be some KT88s like the Gold Lion. I love the look of the Tung Sol and they seem to get good comments on the various HiFi boards out there in internet land. My concern is the voltage ratings on the 6550 vs the KT88. The 6550 has a screen rating lower than my B+, BUT I have heard many times that this rating is somewhat negotiable when running in UL. The rating is more applicable to standard pentode operation. So... has anybody run 6550s in an Eiclone with its 485v B+? And what would the KT88 users recommend for a tube - the Gold Lions are pricey, are the EH any good? Is the JJ quality decent these days? Thanks
justmikey
 
Posts: 14
Joined: Mon Feb 20, 2012 12:22 pm

Postby TerrySmith » Sat Jul 28, 2012 9:03 pm

I've got a set of the Tung-Sol reproduction tubes in my Mark 3's that have the Eiclone front end. So far they sound excellent and have held up well.

FWIW, I also have a set of the new T-S EL34B's in my ST-70 and those are really good sounding also.

Image
T. Smith
User avatar
TerrySmith
KT88
 
Posts: 973
Joined: Sat Jan 31, 2004 12:51 pm
Location: Maryville TN

Thanks

Postby justmikey » Mon Jul 30, 2012 3:15 am

I just fired up an Eiclone last night for the first time. I used a pair of KT88 borrowed from a SE amp I built last yesr. Sounds good. My plate voltage at pin 5 of the KT88 is 505 vdc, screen voltage a couple of volts higher. I set the bias at -60 vdc. What do you have for voltage on your Mk III plates and screens?
justmikey
 
Posts: 14
Joined: Mon Feb 20, 2012 12:22 pm

Re: Thanks

Postby Shannon Parks » Mon Jul 30, 2012 6:13 am

justmikey wrote:I just fired up an Eiclone last night for the first time. I used a pair of KT88 borrowed from a SE amp I built last yesr. Sounds good. My plate voltage at pin 5 of the KT88 is 505 vdc, screen voltage a couple of volts higher. I set the bias at -60 vdc. What do you have for voltage on your Mk III plates and screens?


What's the bias current at this setting?

Shannon
User avatar
Shannon Parks
Site Admin
 
Posts: 3762
Joined: Tue Mar 18, 2003 5:40 pm
Location: Poulsbo, Washington

Postby justmikey » Mon Jul 30, 2012 9:58 am

What I should have said is -600mV across the 10R test point resistors, or 60 ma. That would put me at approx 30w or approx 71 or 72% of the 42w max for a KT-88. Given the screen voltage of just over 500v, it looks like I should stay with KT88 vs 6550 - although it seems to me that the new production Russian tubes have the same guts inside of different bottles - ie they use 6550 or KT88 interchangeably as a marketing ploy.
justmikey
 
Posts: 14
Joined: Mon Feb 20, 2012 12:22 pm

Postby Shannon Parks » Tue Jul 31, 2012 6:12 am

Sounds like you've got them biased perfectly.

I just tested all my KT88s recently and my two old stock (Tungsol? Mullard?) 6550s looked exactly my Sovtek KT88s. FWIW, all of them - including the well abused power supply sourced Genalex KT88s - tested in the 90 to 100% range. Great tubes! EL34s seem to be much more finicky and prone to wear - the price one pays for the extra Gm, I guess.

Shannon
User avatar
Shannon Parks
Site Admin
 
Posts: 3762
Joined: Tue Mar 18, 2003 5:40 pm
Location: Poulsbo, Washington


Return to eiclone

Who is online

Users browsing this forum: No registered users and 1 guest