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 17 Feb 2018, 22:36

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 64 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7  Next
Author Message
PostPosted: 06 May 2009, 16:15 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
18V. then to a pair of 8ohm drivers.


Top
 Profile  
 
PostPosted: 06 May 2009, 21:25 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4529
Location: Winnipeg, CANADA
Ok, so 18VAC is about 25VDC once rectified. Therefore your Vcc is 50V (|V+| + |V-|). From the plot, go up from 50V till you hit the 8 ohm line and then go across and you will see Pd is about 16-17W. Keep going across and if you guess it will be about 40°C or 50°C in the enclosure, you can see that you will want a heatsink with a maximum rating of about 5°C/W.

So your sink is too small.

_________________
[ 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: 07 May 2009, 16:13 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
Hey,
Took me a bit to get that info logged, but with you 100% now. Good eyes gio. Off to RS for new sinks.
Laters


Top
 Profile  
 
PostPosted: 02 Jun 2009, 14:27 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
i think maybe i went mad on the sink!!!! is this too big??? or could i attach two chips to one sink?
Attachment:
LM3886-Chipamp-PCB-Heatsink.jpg


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



Top
 Profile  
 
PostPosted: 02 Jun 2009, 18:00 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 971
Location: Houston, TX
That sink looks fine for a LM3886. I KNOW you wont kill your chips if you put 2 properly insulated chips on there. The sink might get hot depending on the load as far as Ohms and sensitivity and listening level. So try just one channel on it and push it hard for a while. If it gets HOT like 5-10seconds with hand on the sink and then you cant stand it then you are fine with one chip per sink. If it gets warm and not hot then pop the other on. Its not to sophisticated but really what we want is a chip thats not burning up right? My bet is its fine for 2.
RI

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 02 Jun 2009, 20:33 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4529
Location: Winnipeg, CANADA
Hi Sabs,
Do you have a rating for the sink? It is definitely big enough for one chip. If you mount that sink outside of the enclosure you may be able to put both chips on it. Can you should us a photo with the enclosure and where you were thinking of mounting the heat sink.
Cheers

_________________
[ 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: 04 Jun 2009, 16:01 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
Ok got some time to have a think and take some pics.
This was my original layout, imagine that there are wires an all, this is just a lay out of transformers, psu, the preamp and the two channel LM3886.
I was planning on putting a sink on each of the board, but these were too small as gio saw.
Attachment:
P6040016.jpg

This with the top on. I chose a ventillated top to aid convection
Attachment:
P6040017.jpg

With the new sinks (that are quite a bit larger) this is one inside the case with the cover on. There is just enough room.
Attachment:
P6040018.jpg

So i could use a sink on each channel, but i'm wondering is the psu will be too close or if it's overkill. I have space as the case is 45x39cm and 2U high.
Attachment:
P6040019.jpg

Ri said there was a possibility of putting the two channels on one sink. I thought like this.
Attachment:
P6040021.jpg

And in the case thus so. Have on channel upside down, towards the cover.
Attachment:
P6040022.jpg

How does this look? and is one way better than another?
cheers
sabs


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



Top
 Profile  
 
PostPosted: 04 Jun 2009, 16:09 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
Sorry gio,
the spec on the sink is:
Thermal Resistance R 1.3°C/W
Length 75mm
Width 120mm
Height 37mm


Top
 Profile  
 
PostPosted: 04 Jun 2009, 17:07 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 971
Location: Houston, TX
Just from guesses I think you are on the edge of needing two sinks. Without doubt that sink is fine for one channel. I would say, if you want to save sinks, try both on one. If it goes into protection mode (you will think it is dying) then try two. You could of course play it safe and use both. I dont see why not since you have both. But I feel you will probably get away with just one. Sorry, but what is the efficiency of your speakers? Dont know if you posted this before.
Ri

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 04 Jun 2009, 20:41 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4529
Location: Winnipeg, CANADA
You may be able to do both chips on the one sink. If you want to try that, you shoulf test it out before you start to put the enclosure together.

The ventilated top is good. Drilling holes on the bottom plate right below the heatsink will also help.
Cheers

_________________
[ 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  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 64 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 10 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