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 22 Feb 2018, 21:20

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 51 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6  Next
Author Message
PostPosted: 24 Dec 2016, 08:05 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
Just for interest,

I had to try a Mills resistor just for fun. (Pic)
Interestingly the Mills resistor on the CCS made it sound like the SS discreet version I tried earlier using the transistor.
I didn't like the result. Some may like it. It was still quite good but not what I'm looking for.

I still prefer the Ohmite audio gold or Welwyn W22. YMMV

Regards
M. Gregg


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


_________________
What is the sound of one hand clapping?


Top
 Profile  
 
PostPosted: 26 Dec 2016, 11:16 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
For info,

More explanation about the board connections.
Its probably moot most people will just transpose the circuit if they are interested enough.
For any that "May" be struggling. Its pretty straight forward.
At that exit stage left..

Regards
M. Gregg


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


_________________
What is the sound of one hand clapping?


Top
 Profile  
 
PostPosted: 06 Jan 2017, 12:40 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
PSU modification,

Important first cap ground mod.
Note boxes A and B in the negative supply.
Basically it puts the HF inductor between the 600uF cap and the 100uF cap.
This creates the filter with 600uF and 0.1 green cactus >>(10H choke and HF inductor return) >>100uF cap.
This gives more depth to the sound.
The inrush limiter NTC is in series with all caps (Box A in the drawing).
I have also changed the fuse bypass caps to Jupiter red Astron 0.022uF however this is not critical.

Regards
M. Gregg


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


_________________
What is the sound of one hand clapping?


Last edited by M. Gregg on 06 Jan 2017, 13:06, edited 1 time in total.

Top
 Profile  
 
PostPosted: 06 Jan 2017, 12:52 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4834
Location: Australia
Fuse bypass caps? First time I've heard of this. I can see the the logic, what are typical values and what a best caps to use, I'm thinking X2s?

_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 06 Jan 2017, 13:14 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
mwhouston wrote:
Fuse bypass caps? First time I've heard of this. I can see the the logic, what are typical values and what a best caps to use, I'm thinking X2s?


I always bypass fuses on the DC lines.
I use high voltage polypropylene 0.01 uF 1000V on 450V rails and 600V on 250V rails.

The capacitor value is down to damage limitation on DC (charge time) I have uprated to 0.022 red astron on the 250v rails.

You can bypass on AC but only on none safety critical positions. Think of the application as the same as supressing an arc on a switch.

The cap works as an arc quench and stops exploding fuses on the DC rails once the fuse has opened the cap blocks the DC.
However if your going to ask can you hear a difference the answer is I can. YMMV.

Years ago fuses would explode on DC rails and the fuse voltage rating is different on AC compared to DC due to the sine wave creating a quench on the AC as opposed to DC which never changes value and is also supplied with a high current capacitor storage.
You can use X class caps it depends on how safety critical you want to be, I use polypropylene for sonics.
Obviously you don't want the cap to short under fault conditions.

Regards
M. Gregg

_________________
What is the sound of one hand clapping?


Top
 Profile  
 
PostPosted: 06 Jan 2017, 19:01 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4834
Location: Australia
Thanks mate. I rarely fuse my DC. I should though.

_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 07 Jan 2017, 02:45 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
mwhouston wrote:
I rarely fuse my DC. I should though.


Just for interest,
I use inrush suppressors (NTC) on the input to circuits, then you can fuse closer to the running current and the fuses don't blow on magnetisation or capacitor charge on power up. You can fuse the DC rails on the AC before the rectifier then you don't get the problems of trying to break the fault on the DC rail. The problem with that is the capacitor bank can cause a lot of damage by supplying the fault current even after the AC fuse blows. So its a catch 22, how many fuses do you use vs damage limitation to the high voltage winding on the power Tx if the rectifier goes short.

In the past I have used solid state fusing (PolySwitch) on things like heater supplies or DC heaters to protect the mains transformer.
http://www.littelfuse.com/products/resettable-ptcs.aspx
However you have to select carefully due to the low resistance on startup.
Years ago in industry all valve heater circuits used barretter limiters. The incorporation of NTC on the primary winding helps reduce the heater "Shock" high current start up.

The problem with delaying heaters is with DC coupling, then you have to apply damage limitation using things like neon's or diodes from grid to cathode to stop grid overvoltage and arching..LOL it never ends :D

Regards
M. Gregg

_________________
What is the sound of one hand clapping?


Top
 Profile  
 
PostPosted: 07 Jan 2017, 04:45 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4834
Location: Australia
Golly!!

_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


Top
 Profile  
 
PostPosted: 14 Jan 2017, 11:54 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
For interest,

Rectifier test back to cap snubbing:
I tried the BA159 with ferrite bead on the cathode and 0.01uF high voltage ceramic cap bypass.
This gives a closer sound to "real sound" ideas. (Pic)

Just an Alice in wonderland moment:
While rummaging in the spares box I found a short length of 9K Gold wire, I thought its got to be worth a try in the CCS LM317t adjust ground.
So I soldered it with Oyaide SS47. It lasted about half an hour and some 1mm silver went back in.. :D (sounds smoother)

The effect was actually quite good with what sounded like a rounding of the very high frequencies.
This initially sounded like an increase in bass but the sound was less focused (imaging was not so sharp).
The amp also sounded quieter I guess that's the lack of focus having to increase the volume to get the imaging.

That's all folks...perhaps that explains the gold plated silver hook up wire you can now buy and the Mundorf silver gold solder.

Regards
M. Gregg


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


_________________
What is the sound of one hand clapping?


Top
 Profile  
 
PostPosted: 22 Jun 2017, 14:56 
Offline
User avatar

Joined: 01 Jun 2013, 09:05
Posts: 599
Ignore...

I don't want to drag the thread up again but its the only way to add some info.
this its just some extra info and playing about,

Regarding the 1st cap ground mod:
It is possible to put the first cap 600uF negative return on the supply side of the inrush suppressor.
I wasn't sure of the surge capability of the rectifier diodes on start up but it seems OK.

By doing this the transient recovery is better and the HF response is improved.

So the 1st cap is direct after the rectifier and the others are charged via the inrush limiter.
So as you can see in the pic its just the black wire moved to the other side of the suppressor.

Just running 6L6 at the moment..with amperex 12at7<<that's why I wanted to try the heater flash mod.
Again its just for info and testing.<<long term will see if it has any detrimental effects.

Regards
M. Gregg


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


_________________
What is the sound of one hand clapping?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 51 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 17 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