Starting my LM4780 today... Some Q's. - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 11th September 2013, 06:18 PM   #1
mortron is offline mortron  Canada
diyAudio Member
 
Join Date: Aug 2011
Location: Town
Default Starting my LM4780 today... Some Q's.

So I finally have all the essential parts other than a few connectors, and am ready to begin my AudioSector LM4780 kit.

I have a 400VA 22V SumR transformer with dual secondaries, and two rectifier boards worth of parts with my AudioSector kit. Based on a Peter Daniel thread, I seem to recall it best to utilize one rectifier board only for some reason? Is this correct? What would be my best course of action here?

Is there a thread or post that would indicate how to put input potentiometers on the amplifier? I have an imaging issue I currently solve with the use of the power amplifiers input controls.

In the How to Build a Gainclone Power Supply, there is a 35A rectifier used in the safety ground... Is this just a generic one, or would I be using the other one I have the parts for?
http://www.decdun.me.uk/gc/groundlift2.jpg

I have thought about building separates, but am under the assumption there is more to the modification than a few extra power connectors, yes?

Any other advice is welcome, as this will be my first power amplifier build. Thank you. I will be posting pics in my next post.
  Reply With Quote
Old 11th September 2013, 07:33 PM   #2
diyAudio Member
 
Join Date: Oct 2006
Link doesn't work.
Write down what parts do you have.
  Reply With Quote
Old 11th September 2013, 08:02 PM   #3
mortron is offline mortron  Canada
diyAudio Member
 
Join Date: Aug 2011
Location: Town
What do you mean? The link works fine... It takes you to a diagram of a power supply with a safety ground, no?

I'm not sure what youre asking, I listed the parts I have... a 22V Toroid with dual secondaries, and the LM4780 kit from Peter with two rectifier boards. Naturally I have heatsinks as well.
Attached Images
File Type: jpg image.jpg (604.2 KB, 252 views)

Last edited by mortron; 11th September 2013 at 08:31 PM.
  Reply With Quote
Old 11th September 2013, 08:43 PM   #4
diyAudio Member
 
THUMP LUMP's Avatar
 
Join Date: Aug 2007
Nope...Link doesn't work.

But it does now. After I went to the decibel dungeon

Last edited by THUMP LUMP; 11th September 2013 at 08:45 PM.
  Reply With Quote
Old 11th September 2013, 10:16 PM   #5
diyAudio Member
 
Join Date: Oct 2006
As Thump Lump sad, it didn't. If you go to decibel dungeon, then is starts working, or copy paste the link manualy.
You should use 1 rectifier for 1 amp. That is a simple bridge rectifier, I guess you didn't get one then.
I would suggest to ask Peter here on this forum, or directly about the building.
  Reply With Quote
Old 11th September 2013, 10:33 PM   #6
davym is offline davym  Scotland
diyAudio Member
 
Join Date: Jul 2013
Location: Under a cloud
The link doesn't work here either but from what i can make out, you are describing a diode bridge used as a ground lift (see pic below) i didn't bother with one for my LM3886 but i see the attraction. Your spare PSU rectifier board would be wasted if used in that way (my opinion) if you want a ground lift circuit, a common diode bridge would be perfect.

Unless i am very much mistaken (it happens) the two rectifier boards you have are for making dual mono amp's, in which case you would need two transformers.

I would stick as close to the build instructions as possible though, get it working and make any modifications later.


Good luck!


(copyrighted image removed by moderators)

Last edited by davym; 11th September 2013 at 10:39 PM.
  Reply With Quote
Old 17th September 2013, 05:13 PM   #7
mortron is offline mortron  Canada
diyAudio Member
 
Join Date: Aug 2011
Location: Town
I understand the above schematic is not essential to operation, and will consider it, but moving ahead, I have come to this point:

Boards are populated, said for a jumper and the SMD resistors. I have to go pick up IEC sockets and a fuse holder as well as my connectors but was now wondering if this was the appropriate layout for the chassis.

How far fore or aft should I mount the chip along the sink? They measure 4" high, 10.080" deep and the fins are about 2.75" IIRC. As far as possible from the transformer? I assume these sinks are more than adequate for cooling so centreing them won't be as critical, correct?

For my back panel, am I better to use a non-conductive material or? I am planning a wood faceplate with no switches etc, so will likely require an aluminum backing plate. As well, the star ground that Peter Daniel shows is for a much smaller amplifier, is it still logical to run a buss bar for the star ground? Ill try to find the link...
Attached Images
File Type: jpg 20130917_130108_resized.jpg (621.7 KB, 181 views)
  Reply With Quote
Old 17th September 2013, 06:25 PM   #8
diyAudio Member
 
Join Date: Oct 2006
These are insanly huge for 1 chip. I think they would handle 3 per side easily, so I would put them to the 1/4 back and 1/3 from the bottom. But anywhere you like, as you sad as far as you can from the transformer. These are radiators for 100W A class map.
For the back you can use conductive plate, only the conenctor have to be insulated, what is usually true.
Also I know audiosector doesn't use psu caps, but you should. Especially for 4780 chips. Without it the rail voltage jumps like a mad horse around.
  Reply With Quote
Old 17th September 2013, 06:59 PM   #9
diyAudio Member
 
Join Date: Oct 2006
Quote:
Originally Posted by mrWagner View Post
Also I know audiosector doesn't use psu caps, but you should. Especially for 4780 chips. Without it the rail voltage jumps like a mad horse around.
My bad , 2x 10uF Panasonic FC Capacitors.

Do you also have them? For that power you should use at least 4, maybe more. I mean did you buy the 2 rectifier boards only or also the full kit? Just because you didn't show the big caps in the first picture.

Last edited by mrWagner; 17th September 2013 at 07:06 PM.
  Reply With Quote
Old 17th September 2013, 07:53 PM   #10
mortron is offline mortron  Canada
diyAudio Member
 
Join Date: Aug 2011
Location: Town
The two caps on the rectifoer as supplied woth the kit are 10uf and the ones on the amp boards are 1000uf two per board.

Do I need more? I was under the impression its optional if you employ a snubber psu with large caps.
  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
My cabinet treatment project ... starting today TurboFC3S Multi-Way 28 7th September 2006 09:53 AM
Starting my first LM4780 Gainclone amp duelbox Chip Amps 20 24th February 2006 05:29 AM
Starting with my first sub buggsson Subwoofers 5 20th September 2005 08:34 AM
Help, Just Starting Out jawbreak Tubes / Valves 12 11th November 2004 05:19 PM


New To Site? Need Help?

All times are GMT. The time now is 12:51 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