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 Jan 2020, 13:35

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 52 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6  Next
Author Message
PostPosted: 11 Aug 2008, 15:35 
Offline

Joined: 29 Jul 2008, 08:12
Posts: 182
Location: Wiltshire, UK
A little news, I have begun building the newer variant of this amplifier; (http://www.tcaas.btinternet.co.uk/jlh1996.pdf) mainly to see if it an improvement on the old design in my view.

For the power supply, I am going to go big, it'll be at least 500VA, so I have plenty of headroom as far as the suppy goes. Each amplifier has a quiescent current of 1.5A so there'll be plenty left over.

Drawings are coming along too, I'll be posting some screen shots in due course. :D


Top
 Profile  
 
PostPosted: 11 Aug 2008, 16:47 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4580
Location: Winnipeg, CANADA
Is your first one finished up now or are you still working on the supply? Where did you find the original transistors?

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 11 Aug 2008, 16:59 
Offline

Joined: 29 Jul 2008, 08:12
Posts: 182
Location: Wiltshire, UK
The first one's not finished. The friend who's making the case for me is away on holiday, so that's on hold until he gets back. I'm now looking into the power supply. I haven't used the original transistors, as far as I know, they are obsolete. I am using 2N3055s, I have gone for a UK supplier RS, they're far from being the cheapest, but they are at least reputable. 2N3055s are good power transistors, but they're unfortunately a victim of their own success...someone out there is making counterfeit versions of this transistor, and from what I have read, they sometimes slip through the net.

Do you think a 500VA supply is a bit overkill?


Top
 Profile  
 
PostPosted: 11 Aug 2008, 22:19 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4580
Location: Winnipeg, CANADA
500VA is overkiil! :) You likely only need less than 1/2 of that.

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 12 Aug 2008, 02:16 
Offline

Joined: 29 Jul 2008, 08:12
Posts: 182
Location: Wiltshire, UK
Maybe I might go for 300VA in that case.... ;-) The thought Of having a bigger supply now was for future upgrades, just in case. That said, I can always build the supply big, and use a lower rated transformer for now. :)


Top
 Profile  
 
PostPosted: 12 Aug 2008, 06:47 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
Here is a nice 400VA toroid that will likely cost you the same as a 250VA or 300VA. I use this for a chip amp. Its overkill there to, but it was cheap and works like a charm. The 18V seems to be what you need to get 22V rails as specified in your pdf.
http://cgi.ebay.com/18-18V-400VA-Toroid-Transformer-Stepper-Motor-Driver_W0QQitemZ370075436273QQihZ024QQcategoryZ4660QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Actually it will give you about 24V rails but I think that will be fine for you.
This is what it says for specs
1. Primary I = 0.02A, Secondary V = 18.4VAC at 0.0A, Power = 0 Watt
2. Primary I = 0.65A, Secondary V = 18.1VAC at 3.61A, Power = 65 Watt
3. Primary I = 1.20A, Secondary V = 17.7VAC at 7.08A, Power = 125 Watt
4. Primary I = 2.77A, Secondary V = 16.6VAC at 16.59A, Power = 275 Watt
5. Primary I = 4.00A, Secondary V = 16.4VAC at 24.11A, Power = 400 Watt

When I rectify this transformer I get EXACTLY 24V. This is with very small load. So a bit larger load would seem to indicate you will get 22-23V.

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 12 Aug 2008, 12:06 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4580
Location: Winnipeg, CANADA
Hi johnmcquay,

Yeah, 300VA should be more than enough, but as you mention, you can always use the bigger transformer somewhere else later on.

Ri, I have looked at that guys auctions before, but shipping to Canada is excessive.

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 12 Aug 2008, 15:03 
Offline

Joined: 29 Jul 2008, 08:12
Posts: 182
Location: Wiltshire, UK
I wonder what shipping to the UK is like.... ;-)


Top
 Profile  
 
 Post subject: Q
PostPosted: 12 Aug 2008, 17:42 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
But Mr McQuay had no known location til now :) So I figured he might be US and be able to use this. Yeah out of the country would be pretty expensive.

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 12 Aug 2008, 17:48 
Offline

Joined: 29 Jul 2008, 08:12
Posts: 182
Location: Wiltshire, UK
Indeed. I was the self-designated homeless. lol ;)

Not mentioned it until now, but I'm going to be working on a pre-amp too. Going to be ordering a kit from Rod Elliott, I don't know if anyone else here has tried his Project Project 37-A, but I'll be ordering one soon. http://sound.westhost.com/project37a.htm


Last edited by johnmcquay on 12 Aug 2008, 17:52, edited 1 time in total.

Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 52 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: Google [Bot] and 1 guest


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:  
cron
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