DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 26 May 2018, 16:24

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
 Post subject: KT120 tubes in Oddblocks
PostPosted: 05 Oct 2017, 15:52 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3649
Location: Arizona, USA
Hi Everyone, I'm looking for info....has anyone used Asian tubes in the KT120 Oddblocks or even in class A single ended amps. I'm hunting for something to replace the Tungsol ones as the new ones can not handle the dissipation (at about 85%) in the amplifiers.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 06 Oct 2017, 00:01 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2208
Location: Chilliwack, BC
KT-120 seem to be tied up by T-S this side of the pond... I see images for Shuguang Treasure KT-120, but no places to buy them :confused:

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 06 Oct 2017, 16:27 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3649
Location: Arizona, USA
Hi Everyone, I had a request for photos of the differences. The new tubes are only able to handle 75% (absolute max) of the rated dissipation in Class A U/L. Still about 25% better than KT88s and they cost the same. We knew it was too good to last. The early ones can do as much as 90%. I have a pair in my personal amps (for longevity testing) running 94%. Been there nearly 5 years and are just fine.

Notice the changed fins and different support structure in the new tubes. It kind of looks like they had to change the supports and then discovered the fins didn't clear them. So they squashed the fins. In off line correspondance I suspect that there ar enow two versions of the tube type. One for everyone except the big companies. Those are more like the old ones and bear the company's names and logos. Seems like we are all second class citizens.

Good listening
Bruce
Attachment:
KT120s Ae.jpg
Attachment:
KT120s Be.jpg


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 07 Oct 2017, 03:01 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2208
Location: Chilliwack, BC
If it were me, I'd just terminate all KT120 designs if I didn't have the funds to lawyer-up :bawling:

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 07 Oct 2017, 17:13 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 3649
Location: Arizona, USA
Maybe I'll use 6C33s next :evil: 4CX1000s might do the job...except where whould I put the massive radiator needed to cool them? :hot:

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
PostPosted: 08 Oct 2017, 12:23 
Offline

Joined: 25 May 2016, 16:30
Posts: 45
I don't recommend 6C33s. Notoriously unstable and no production for many a year. 845s last forever and are really reliable. Could they run at eg 600v?


Top
 Profile  
 
PostPosted: 08 Oct 2017, 18:31 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2208
Location: Chilliwack, BC
I was pondering your issue, Bruce and came up with the same as Juancho, LOL!

845's IMHO are "mosfetty" in sound, so you'd need to squeeze some sonics from the driver. I'll happy share some circuits via email with you if you're interested :)

@Juancho - 845's are very forgiving of anode voltage, but they don't come into their glory under 800V. A good, ol' fashioned doubler supply a-la Citation-II (only more voltage) would be called for as Edcor won't make them (we designed the XPWR169-120) HV due to CYA liabilities. However, we did design with Edcor an 845 OPT, the EM0774 (unlisted, but available. See thread - http://edcorusa.com/boards/topic/241/mi ... m-the-list ).

Cheers!

*edit*
I just remembered the Oddblocks are PP.

850-900V B+ and this wee beastie should do:
http://edcorusa.com/cxpp100-42k

1KV-1100V this:
http://edcorusa.com/cxpp100-5k

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 09 Oct 2017, 08:55 
Offline

Joined: 30 Aug 2017, 09:49
Posts: 35
I have used over 20 pair of edcorCXPP100-10K transformers at 1000v to 1100v with no problems for years with no prolbems. The only problem I ever had with Edcor was power transformers. Every one that I used went to a dead short with out any warning. I am talking about the 1100 volt 400ma 6v 4a 6v 2a that are no longer made. Ever since then I use only Antek power transformers. All of the edco r power transformers lasted a little short of 5 years. Never had problem with outputs though.

_________________
Alpha Wolf


Top
 Profile  
 
PostPosted: 09 Oct 2017, 16:34 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2208
Location: Chilliwack, BC
Alpha Wolf wrote:
The only problem I ever had with Edcor was power transformers. Every one that I used went to a dead short with out any warning. I am talking about the 1100 volt 400ma 6v 4a 6v 2a that are no longer made.


Probably why Edcor discontinued my 1500V XPWR169 :confused:

Never had a PT problem from them, but I also overdesign.... I use a transformer that's only at 50-65% of its ratings when the amp is full tilt. Preamps I'll do 75%.

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


Top
 Profile  
 
PostPosted: 09 Nov 2017, 13:31 
Offline

Joined: 25 May 2016, 16:30
Posts: 45
Good news guys, the latest set of KT120s I bought are completely happy at 124ma dissipation. I've set the amps there specifically for a customer. Once he's done his home demo I'll try at 137ma but these 120s are doing much better than 20 out of 24 KT150s tried over recent months


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy