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 29 Mar 2020, 14:22

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 484 posts ]  Go to page Previous  1 ... 20, 21, 22, 23, 24, 25, 26 ... 49  Next
Author Message
 Post subject: Re: KT120 Oddblocks
PostPosted: 26 Feb 2017, 18:23 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2229
Location: Chilliwack, BC
gofar99 wrote:
Hi, I would attach the screen via a resistor to the anode. Something in the 470 ohm range would seem appropriate.


And for luck's sake, non-inductive.

Had a Gold Lion KT88 monoblock with a 1K metal film on the screen... *just* enough g2 to A mu to make a little 470MHz transmitter. Changing them to carbon film cured it :D

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


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 27 Feb 2017, 05:24 
Offline

Joined: 18 Jun 2016, 06:52
Posts: 28
Thanks guys. Better safe than sorry.


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 27 Feb 2017, 10:21 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 4097
Location: Arizona, USA
Hi, I never had one transmit, but one did a 0.5HZ full power square wave and another made for a nice arc welder....beautiful display. :firefighter:

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 04 Mar 2017, 05:58 
Offline

Joined: 25 May 2016, 16:30
Posts: 56
The arc welding display was nothing to do with running in triode mode I hope?


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 04 Mar 2017, 14:34 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 4097
Location: Arizona, USA
t'was the super double duper pentode plus mode :up:

good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 18 Mar 2017, 14:27 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 4097
Location: Arizona, USA
Hi Everyone, It seems that Tungsol has changed the design or build of their KT120s and KT150. Right now it seems that it is necessary to reduce the voltage on the screens to avoid re-plating the anodes near the screen supports. This was not the case in the earlier tubes but now may be needed. Earlier you could use the full B+ on the screen in U/L mode. Now it seems that you will need to add resistance to get it under about 250 vdc. This really should not matter to the amps and ought to be sonically transparent. Still it would have been nice to get a manufacturer's notice of such a change. More to follow.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 29 Apr 2017, 14:40 
Offline

Joined: 07 Mar 2017, 03:14
Posts: 103
Hi Bruce,
Are the following transformers correct for kt120 monoblocks.

Output transformers: http://www.edcorusa.com/cxpp70-35k

Power transormers: http://www.edcorusa.com/xpwr267

If xpwr267 is correct transformer for this project, I see it can provide 4 amp heater current. Is this enough? When I look at kt120 specs, I notice it needs 1.7-1.95 amp heater current. 12SL7 needs 0.15 amp. So the needed current for heaters may be over 4 amp in some cases. Even it does not go over 4 amp, since it's very close, do we overload the power transformer?


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 30 Apr 2017, 08:43 
Offline
Project Author
User avatar

Joined: 04 Jun 2008, 20:59
Posts: 4097
Location: Arizona, USA
Hi, The KT120 heaters are in series and need only about 2 amps for the pair (at 12 volts). That transformer was designed by Edcor for these amps. I use it in the commercial versions. BTW you do need to go the DC heater route with it. When rectified and filtered you get the needed 12vdc. The other transformer is fine. Same size with the 4.2K primary is also OK. The differences in performance are quite small and not audible.

Good listening
Bruce

_________________
Some of my DIY Tube Amplifier Projects:


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 30 Apr 2017, 14:34 
Offline
User avatar

Joined: 08 Aug 2009, 03:11
Posts: 2229
Location: Chilliwack, BC
gofar99 wrote:
Hi Everyone, It seems that Tungsol has changed the design or build of their KT120s and KT150.


Talked to my distributors about this. Seems T-S is committing some economic suicide as they lost three fair sized manufacturers to Shuguang doing this.

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


Top
 Profile  
 
 Post subject: Re: KT120 Oddblocks
PostPosted: 01 May 2017, 09:45 
Offline

Joined: 07 Mar 2017, 03:14
Posts: 103
Thanks Bruce. Have you tried 0.47uF caps on the signal path before? Some think they provide the most frequency bandwidth.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 484 posts ]  Go to page Previous  1 ... 20, 21, 22, 23, 24, 25, 26 ... 49  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Guavatone and 16 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