Salas hotrodded blue DCB1 build - Page 247 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th November 2012, 10:38 AM   #2461
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Is it PSU or BUFFER fault ??

Check output voltages of the PSU.
  Reply With Quote
Old 26th November 2012, 10:44 AM   #2462
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by dtses View Post
thanks! is it safe to keep them above 60c? Anyway I was planning to attach them to the chassis.

Its true those diodes have a high 175C internal junction break point, but electronics do last 4 times longer each time you halve their operating temperature. So don't be much afraid for them during testing but help them when finishing the build because it is likely they are going to live in high ambient in that hot rod box. For the electrolytics, especially the big ones,they will fair best if 105C rated.
  Reply With Quote
Old 26th November 2012, 10:45 AM   #2463
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by KatieandDad View Post
Is it PSU or BUFFER fault ??

Check output voltages of the PSU.
What fault? He is referring to voltage drop across CCS setting resistors. Not rails voltages.
  Reply With Quote
Old 26th November 2012, 12:07 PM   #2464
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
I was referring to POST 2449. He seems to have afaulty amplifier ??
  Reply With Quote
Old 26th November 2012, 12:15 PM   #2465
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by dtses View Post
..............0.71 1 W/(m.K).......for Mica and .............0.6 for Kapton......or even 0.12
note the units, W/mK
The 0.71 looks like the highest Watts. That makes it the best. But you must also take account of the thickness.
Mica generally comes in thicknesses varying from 1thou (1mil= 0.001") to 6thou (6mil = 0.006")
Kapton tape in thickness varying from 1.5thou to 6thou.
Coated Kapton in thickness varying from 3thou to 9thou.

The very thinnest mica outperforms all the coated Kaptons and is just about equal to a gooped Kapton of 1.5thou if you can find any uncoated Kapton tape that thin. Uncoated Kapton will need goop on both sides. Makes it just as messy as Mica.
__________________
regards Andrew T.

Last edited by AndrewT; 26th November 2012 at 12:20 PM.
  Reply With Quote
Old 26th November 2012, 12:17 PM   #2466
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by KatieandDad View Post
I was referring to POST 2449. He seems to have afaulty amplifier ??
Ah, that was in another page. He must check his semis and everything really.
  Reply With Quote
Old 26th November 2012, 07:54 PM   #2467
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
Put evrything in the case and attached the fets with metal bolts, closed the lid and let it warm up for about 40 mins. So here is what i got:

-1.87 & 1.97vdc across 3ohm R
-0.01 & 0.09 mA offset
-10.79 & 10.79 vdc output
-42c on the fets
-about 40c on the sinks (barely warm when I touch them)
-62c on the surface of poor little toroid placed out of the case

The whole case i kind of a heatsink. I didn't use any thermal paste yet. The are ventilation holes only on the top lid, so I assume need to add some to the bottom...

How more may I torture this little toroid, is it safe to put another 6R across, making it close to 1A per rail?! I do not have any spare transformers, only if I borrow 100VA 2x18vac from MyRev FE, but I'm not sure if that is a good idea and would give similar result as with a decent 2x15vac toroid.

Another question is how far could I go with these heatsinks and what toroid to buy in the end. As it should be less than 78mm in diameter according to my layout, this narrows the choise to <80va toroid or I should be looking for R-core (65w and it would suit the case) like this one. Alternatively some custom toroid, 50-55mm in height needs to be found.

Btw, sorry for probably stupid question but is it possible to connect 2 x 50va transformers in some way?! That woul solve the problem

Last edited by dtses; 26th November 2012 at 08:08 PM.
  Reply With Quote
Old 26th November 2012, 09:10 PM   #2468
diyAudio Member
 
dimkasta's Avatar
 
Join Date: May 2010
Location: Athens
Offset you mean mV?
A photo of the case should help us see any possible solutions to your trafo real estate problem.

About the 2x18V trafo, if you decide to try it make sure that the V on the filter caps does not exceed the V rating of the caps (~25V expected for 18V secondaries)
  Reply With Quote
Old 26th November 2012, 09:39 PM   #2469
diyAudio Member
 
dimkasta's Avatar
 
Join Date: May 2010
Location: Athens
I finally wired everything together on the chassis. That thing ended up HEAVY!!!

First impressions with the Caddocks are very very very very very very positive
Although having everything securely screwed on that dense and heavy chunk of metal and wood might also played a part.

Imaging and separation are in a completely new level. Mids are amazingly sharp and precise. It sounds a bit shy on the mid-lows, but it is probably the fresh soldering/wiring. It will show in a few days.

With no lid on and after 2 hours the temperature on the fets is 48C which is very close to what I wanted. The heatsinks stay at about 35C. A properly vented lid should not create any additional issues. I am thinking glass or some more wenge.

What troubles me a bit is the wire spaghetti because of the pot on the front and the DPDT switch on the back for the source selection (That one is a switchcraft and is of very nice quality (a bit pricey though)). I bet that with shorter and better separated wires the results would be better... Even better with a dual mono build but... meh...

The only thing remaining for now is to properly drill the knob and install it.
Oh and do something about that damn white led which is too bright

Click the image to open in full size.
Attached Images
File Type: jpg DIM_1322.jpg (182.1 KB, 419 views)
  Reply With Quote
Old 26th November 2012, 10:37 PM   #2470
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
@dtses
You could attempt 1A it looks like with your now sinking and measured temps. The limiting factor is your little hot transfo obviously. 2x18V forget it, the spare voltage will convert to high heat on the CCS and sink. Ebay R-Cores are a gamble. When made right its the best solution, when not, a downright failure for heating and buzzing. Feeling lucky on the one you linked? China is slow shipping lately except HK have in mind. About the using two little ones question: You can in general stack or arrange side by side 2x15V 50VA toroids (or any other type) and wire them in parallel. There are restrictions when paralleling though. Thus they should be coming from the same manufacturer and be same model having very low tolerances between them, and they should be wired with same magnetic polarity. Toroid's central screw should not touch the top lid. If it will you are for witnessing a catastrophic magnetic short. But you already have 630mA on average which is decent hot rod in the compact. Another option would be a 100VA single toroid in another box, saving you the hum field also. You decide based on discussed info.

@dimkasta
Nice.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
dcb1 buffer with shunt reg. merlin2069er Swap Meet 0 3rd August 2010 05:25 PM
F2 and DCB1 parts selection - please advice! DQ Pass Labs 6 25th November 2009 03:20 PM
Y B Blue - how blue LED improves the CD playback Peter Daniel Digital Source 176 25th September 2003 07:40 AM


New To Site? Need Help?

All times are GMT. The time now is 12:03 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2