LM1875 Micro Clone - 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 30th June 2006, 08:14 AM   #1
diyAudio Member
 
Join Date: Apr 2006
Location: Goulburn NSW
Default LM1875 Micro Clone

Here are a couple of pics of a LM1875 based micro clone now under construction, it is small but I have an even smaller purpose built tweeter amp also under contruction with all point to point smd parts.

What you see here is without the input caps and a few other bits, but it gives the idea, witht he ground plane on top earth lenght are about as shaort as possible.

The overall amp design is the final incarnation of 12 experimental modules. its been up and running and it sound brilliant to me anyway, in fact I have the same layout on a regular PC but the micro clone sound clearer and more detailed. In fact pretty much like a good valve amp without the bass issues.

A few specs. 12V smps or 18V battery supply, 13,000 uf cap per rail, remote from module, gain of 18, and lots of small tweaks etc.

The whole module is in a sealed alloy housing which attaches to the heatsink for additonal cooling duty, however the whole things runs virtually stone cold.

I will post a full set of build details and pics in a fortnight or so.
Attached Images
File Type: jpg micro1-a.jpg (56.6 KB, 1191 views)
  Reply With Quote
Old 30th June 2006, 08:17 AM   #2
diyAudio Member
 
Join Date: Apr 2006
Location: Goulburn NSW
Here is another pic of the module without the ground plane.
Attached Images
File Type: jpg micro2-a.jpg (45.3 KB, 1133 views)
  Reply With Quote
Old 30th June 2006, 04:36 PM   #3
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
With such low supply voltages it will run pretty cool. Is that a single supply voltage of 12 - 18V or split so it needs two batteries? Why did you use the LM1875 verses something like the LM4701? Just curious. Nice little amp you got there.

-SL
  Reply With Quote
Old 30th June 2006, 06:38 PM   #4
diyAudio Member
 
Join Date: Mar 2003
Location: Windsor
I realy like these little mini LM1875 designs. I did one myself some time ago, but it was on a PCB. Here is the link to a shot of it.

http://www.diyaudio.com/forums/showt...179#post760179

It's a double sided board, very minimilist design. If I want to add some small decoupling caps I can solder them to the bottom side, but I haven't bothered. For an imput cap I just solder it in series with the phono connector.

I imagine soldering those SMD resistors P2P was fun!

G.
__________________
If you take something apart and put it back together again enough times, eventually you will have two of them.
  Reply With Quote
Old 30th June 2006, 11:55 PM   #5
diyAudio Member
 
Join Date: Apr 2006
Location: Goulburn NSW
(Is that a single supply voltage of 12 - 18V or split so it needs two batteries? Why did you use the LM1875 verses something like the LM4701? Just curious. Nice little amp you got there.)

Hi there Lama, the amp modules are dual supply and currently they are running of 4x 18V battery drill packs, until I build the power supply, which will be an auto charging dual 18v using 6 x 6v SLAs.

I have tried other chips, but to me the LM1875 sounds the best on low volt supplies, if you look at the spec sheets for all the Nat Semi chips you will find the power output of all the chips is pretty similar for the same voltage, the higher output is only obtainable with higher Vs and the 1875s top out at about 25V where as the higher powered chips handle higher voltages and thus give higher output.

Something very sweet happens to the sound with these chips if run at lower voltages, and in fact the LM1875 seems to work the best of the lot at 12V for example, in fact it actually produces just a little more power on 12V than the other chips in the Nat Semi stable, though you wouldn't notice.

The chips are very sensitive to the quality of the supply, after tryiing torroids, smps and battery power in different voltges, 18V battery power seems to be the ultimate source with 12V smps and lots of capacitor reserves a close second and regular transformer power in 25V-30V a very distant last.

Power output is not an issue if you are using very efficient full range speakers, which I am, however this isn't a good set-up for a pair of hard to drive speakers.


(I imagine soldering those SMD resistors P2P was fun!)

Yep you can say that again, I nearly went mad until I worked out a good technique, its pretty easy now, but I have to be very careful not to break anything while still in the construction phase, as it is very hard to fix and of course it is a littel fragile, hot melt glue in the right spots helps to keep things solid once finished.
  Reply With Quote
Old 5th July 2006, 05:36 PM   #6
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
Thanks for the info. I have never listened to a LM1875 but I know the LM4700 and LM4701 are the same chips used in the LM1876 and always thought it sounded very good. You're right on the output power are lower supply voltages. I like your supply idea, pretty cool.

-SL
  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
Micro MR-711, My first DD Turntable bulgin Analogue Source 0 31st May 2009 03:14 PM
Micro Jacks and Micro Pins for board-board connection jazzist Parts 1 12th May 2008 03:02 PM
micro-amp SE with 2,5k OPT+ boergars Tubes / Valves 3 11th July 2007 02:58 AM
Micro DQ-5 TT anyone? Lorne Analogue Source 0 22nd November 2004 03:36 PM
Question regarding ProAc 2.5 Clone and Tempo 2 Clone zoooh Multi-Way 5 11th March 2003 08:19 PM


New To Site? Need Help?

All times are GMT. The time now is 01:12 AM.


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