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 21 Aug 2018, 01:22

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 76 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8
Author Message
PostPosted: 08 Nov 2010, 18:56 
Offline

Joined: 23 Jul 2010, 18:23
Posts: 23
Thanks for the offer. Here is a pic of the assembly. I welcome any criticisms of my construction.


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



Top
 Profile  
 
PostPosted: 08 Nov 2010, 19:48 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1446
Location: US Pacific Northwest
Your build looks very clean :up:, so I would begin looking for a ground loop problem. The return signal paths should never from a loop of any kind. And the signal ground should only connect to the chassis ground at one point. In this way you keep ground currents to a minimum.

I did notice one thing that looked suspicious. It looks like your circuit board ground is tied to the chassis at two separate points but I can't be sure because the one wire is obscured by the transformer primary wire.
Attachment:
grounds.jpg

I cannot emphasis enough the need for careful grounding when working with voltages this high. I speak from (a bad) experience. :worried: http://www.linxure.net/~renaudnw/tubes/Tube_Site/The_First_Amp.html

I would begin looking for places where you could have ground loops. Some common examples are shield leads with the shields tied to ground at both ends, grounded input jacks, grounded output jacks, potentiometers cases tied to signal ground, using the chassis as a power supply return, etc. I think you should get the idea. Also look at where you mounted the circuit board to the chassis and make sure that one of your screws doesn't unintentionally carry the signal ground back to the chassis.

I hope this helps. Your amp interrior looks very good, it could be just one or two wires giving you the problem.


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


_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
PostPosted: 08 Nov 2010, 19:58 
Offline

Joined: 23 Jul 2010, 18:23
Posts: 23
Matt -

Thank you for the comments. I know nothing about this. I just followed the directions. So, I connected one lead from each output transformer to the PCB at the points indicated in the directions with the kit. Your arrows do point to the two separate connections I used. If you say that the two wires should be connected at one point, I will do that.

I also used a ground loop interrupter on the input cables but it made no difference.

Thanks again I will keep working on it.

-- Chuck


Top
 Profile  
 
PostPosted: 19 Nov 2010, 17:39 
Offline

Joined: 27 Oct 2010, 20:27
Posts: 28
Similar question: I'm mounting my transformers on the top of an aluminum chassis, should I then only ground ONE of the transformers to the PCB and make that my single ground connection from chassis to pcb to avoid ground loops... this should ground all three transformers if they're all mounted on the aluminum chassis, correct?


Top
 Profile  
 
PostPosted: 19 Nov 2010, 20:41 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1446
Location: US Pacific Northwest
A good way to think of transformer end bells and frames is as a chassis to protect the circuit portions of the transformer. They shield the transformer in the exact same way that a metal chassis shields the internal parts of the amp. As such, transformer end bells and frames should be grounded to the chassis ground. The circuit grounds should all be tied to a signal ground. Then the chassis ground and the signal ground should be tied together at one and only one point. This will prevent chassis ground loops.

Make sense? :?:

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
PostPosted: 20 Nov 2010, 09:54 
Offline

Joined: 23 Jul 2010, 18:23
Posts: 23
Thanks Matt for that explanation.

One thing that I wondered about this kit. In the stock build on a breadboard, each of the frames on the output transformers have a ground wire running to the PCB but there is no ground from the frame of the power transformer. I just figured it was OK like that. Then, I was told by Mark on this board to add a ground for safety - (thank you, Mark)

So, now with your explanation, Matt, it seems that I should tie together the grounds from the chassis and xfmr frames. I guess S5 Elec had the grounds running to the PCB because there is no chassis in stock form. I assume that all the grounds on the pcb are connected. So, hooking up the grounds as they instruct combines chassis and signal grounds? I will rerun the grounds and see if it eliminates the hum.

-- Chuck


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 76 posts ]  Go to page Previous  1 ... 4, 5, 6, 7, 8

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Majestic-12 [Bot] and 15 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