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 30 May 2020, 14:37

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 251 posts ]  Go to page Previous  1 ... 21, 22, 23, 24, 25, 26  Next
Author Message
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 08 Jan 2020, 17:23 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5226
Location: Australia
john55 wrote:
My wife turned up with a 1947 Marconiphone radio the other day. She thought I might want to try to get it working.
I don't have much interest or knowledge in radio but decided to give it a look over. I managed to salvage the little mono amp that I can play with later, but as for the receiver..... I didn't have a chance (I don't know about the USA but here in Spain I don't think anyone broadcasts on SW / MW / LW anyway).
Then I looked at the case, dull brown bakelite but not a scatch or crack on it anywhere. A bit of soapy water and dasboard polish and look what I've got.
This is going to house the 6V6 and tone stack that I've been asking questions about in the last two or three posts on this thread. It might be a bit of a squash but I've got height as well as width and depth. Any thoughts?

Looks good.

_________________
Projects:"Zeus" - Holton inspired 300W AB amp | "Pass F5 trubo” - dual mono high-end amp | “MWH” - 1920s UX-171A preamp | ”Image” - Low Profile 100W Class D amp |


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 13 Jan 2020, 12:22 
Offline

Joined: 13 May 2016, 02:02
Posts: 152
Location: Javea, Spain
This chassis is a bit tight to fit everything, but that's all I've got if I want it to fit in the Marconiphone case.
I've kept the two 12AU7's and the 6SN7 as far away from the mains transformer as possible. Are they far enough away or am I asking for problems?
I would prefer to keep the 32uF+32uF capacitor on the top plate if possible but could move it underneath if the heat from the 5U4GB and the 6V6 on either side of it would cause problems. Asking for advice here as I have read that capacitors don't like heat.


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



Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 24 Mar 2020, 06:34 
Offline

Joined: 13 May 2016, 02:02
Posts: 152
Location: Javea, Spain
If nothing else, a four week lockdown concentrates the mind. I’ve been trying to get this finished for months.


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



Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 24 Mar 2020, 17:44 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1651
Location: US Pacific Northwest
john55 wrote:
If nothing else, a four week lockdown concentrates the mind. I’ve been trying to get this finished for months.
John;

It looks superb! As always you workmanship is top notch. The integration with the case is really nice.

I'm here in the USA outside of Seattle, WA and we are just starting a 14 day lockdown to contain virus spread. I'm still working but saving a couple of hours a day in commute time. I really should put all that extra time to good purpose. ;)

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


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 30 Mar 2020, 11:39 
Offline

Joined: 13 May 2016, 02:02
Posts: 152
Location: Javea, Spain
I noticed something strange when I turned off my latest amp (pictures above) today. The ammeters needles bounce instead of dropping smoothly. Could someone take a look at this short video and perhaps tell me what's going on. https://theleathershop.biz/page212.html


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 30 Mar 2020, 14:34 
Offline

Joined: 19 May 2011, 05:38
Posts: 46
Possible "pop" sound when you turn off the power. Will cause power spike with gradual bleed off of the capacitors


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 30 Mar 2020, 16:14 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1651
Location: US Pacific Northwest
john55 wrote:
I noticed something strange when I turned off my latest amp (pictures above) today. The ammeters needles bounce instead of dropping smoothly. Could someone take a look at this short video and perhaps tell me what's going on. https://theleathershop.biz/page212.html
Your power switch should be behind the power transformer and PS filtering. As such, the currents should just slowly fall as the B+ fall while current is pulled off the PS filter. Does this happen on both channels or only one? If both, do the needles move in synchrony?

The power switch transition on the primary side of the power transformer should not cause this behavior. Do you have an As-Built schematic? We need to see details of exactly how the power supply was wired. Honestly, for the time being I am at a loss.

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


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 31 Mar 2020, 05:04 
Offline

Joined: 13 May 2016, 02:02
Posts: 152
Location: Javea, Spain
I have wired the power supply as per the schematic on the previous page (dated 13th April 2019) with the exception of the 350 ohm 5 watt dropping resistor which I've left out (I always have slightly less voltage here in Spain). I have to do this with all builds.
My voltage readings are: 280v to output transformers, 250v to 6SN7 and 275v to tone stack pre amp. All readings taken with amp fired up and under load.
No "pop" when switching off.
It happens on both channels and the needles move in synchrony.


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 31 Mar 2020, 07:27 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1651
Location: US Pacific Northwest
Where exactly is the power supply bleed resistor connected and what is the value of the resistor.

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


Top
 Profile  
 
 Post subject: Re: "Lacewood" Amp V2.0
PostPosted: 31 Mar 2020, 10:34 
Offline

Joined: 13 May 2016, 02:02
Posts: 152
Location: Javea, Spain
Matt, My understanding of a bleed resistor is a resistor in parallel with the cap or caps so I would expect to see it across the power supply outputs. I assumed the resistors in the schematic (20k and 2k7) somehow do the same job.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 251 posts ]  Go to page Previous  1 ... 21, 22, 23, 24, 25, 26  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users 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