Leach Amp Project - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 18th August 2011, 11:10 AM   #1
Toltec is offline Toltec  United Kingdom
diyAudio Member
 
Join Date: Aug 2011
Location: Birmingham
Default Leach Amp Project

Hi All,

After many years away from hobby electronics I've decided to get my hands dirty again and build the Leach 4.5. My plan is to build it precisely as per Prof Leach's plans. Besides the enjoyment of doing this, I'd like to know that the end result will be better than my current setup, which is:

CD Player: Marantz CD7300
Amp: Marantz PM7200
Speakers: Bowers and Wilkins DM603 S3

I intend to reuse the CD player and speakers, possibly upgrading in the future sometime. In the opinion of the forum, can I expect as good or better performance with the Leach? Any opinions will be appreciated.

Toltec
  Reply With Quote
Old 18th August 2011, 11:25 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I don't know your amp nor your speakers.
Are the speakers 4ohm or 8ohm or some other impedance?

I would expect the Leach Lo Tim 4.5 to drive 8ohms very well, but with a two pair output stage and low efficiency, 4ohms speaker, it may not be at it's best. A big PSU will help.

The Leach is pretty good, I think you will be pleased.
__________________
regards Andrew T.
  Reply With Quote
Old 18th August 2011, 11:36 AM   #3
diyAudio Member
 
Join Date: Apr 2011
Location: Pretoria
Will you limit the pre-amp to a volume pot with no input selector, tone controls or (oh my goodness) loudness button?

Would work fine of course.

Just bear in mind that the Leach amp is not really a beginner project, but if you have wielded a soldering iron before you should be OK.
  Reply With Quote
Old 18th August 2011, 12:07 PM   #4
Toltec is offline Toltec  United Kingdom
diyAudio Member
 
Join Date: Aug 2011
Location: Birmingham
Thanks for the replies. The speakers are 150W 8 ohms 90dB/2.83V/m floor standers. The amp 95W into 8 ohms.

Yes, since I only use my amp for CDs I only intend using a volume pot. I'm on the brink of ordering the components from Mouser... looking forward to the smell of solder again!
  Reply With Quote
Old 18th August 2011, 12:26 PM   #5
diyAudio Member
 
Join Date: Apr 2006
Location: PARIS
Hi,
Leach amp is a very good choice. Why ? Because you will find all documentation on Leach's site, see FAQS for more details.
Regarding speaker impedance : No probleme for 4 ohms. This amp use two pairs of Bipolar (140 V 20 A 250 W !!) But it could be necessary to adjust current limiter. But is it realy necessary ? For normal use, i am not sure.
Please see those links :

Leach Amp Protection Circuit

The Leach Amp - Part 2

Regards,
Frédéric
  Reply With Quote
Old 18th August 2011, 12:45 PM   #6
osscar is online now osscar  Latvia
diyAudio Member
 
osscar's Avatar
 
Join Date: May 2009
Location: Riga, LV
For your speakers Leach amp power will be sufficient IMHO. Many do not like the TO-3 transistor assembly - for such there are also versions for Leach with on-board plastic transistors. good luck !
__________________
If time is money then I'm out of time
  Reply With Quote
Old 18th August 2011, 01:32 PM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
expect a lot more than 95W into 8r0 from the Leach.
I don't know where that figure came from.
I built the Leach clone with the 3pair output stage.
From 230:40+40Vac transformer I got 170W into 8r0, one channel driven. My 3pair of 230W plastic (MJL) devices has similar SOA to a 2pair To3 using 250W devices.

I got over 300W into 4r0, one channel driven, but that does not prove it is 4ohms capable.

Look at using the NJL devices with the integrated diodes. These 4 diodes would fit exactly into the Lo Tim 4.5
__________________
regards Andrew T.

Last edited by AndrewT; 18th August 2011 at 01:35 PM.
  Reply With Quote
Old 25th August 2011, 08:54 PM   #8
Toltec is offline Toltec  United Kingdom
diyAudio Member
 
Join Date: Aug 2011
Location: Birmingham
Thanks all for your input.

I'm in the process of buying components. I intend making the pcb myself. I'd prefer to use 2 oz copper but it seems that getting it in the UK is all but impossible unless you're willing to pay mad shipment prices from the US or the East. Is 1 oz ok?... perhaps doing as someone else suggested elsewhere and soldering copper wire along the high current traces. Any input would be appreciated!

Gary
  Reply With Quote
Old 26th August 2011, 09:37 PM   #9
diyAudio Member
 
Join Date: Jul 2004
Location: Edmonton, AB Canada
I would recommend 2oz copper and laminate thicker than 1.6mm (0.062") for power amps. A PCB house starts with 1oz and electroplates to 2oz, for typical double-sided boards. Solder has almost 10X resistance of copper, so adding solder to PCB traces does not help as much as we think.
diy member Jens Rasmussen did some nice Leach amp clone PCB's that you should checkout:
DELTA AUDIO - Leach Amp Clone
  Reply With Quote
Old 26th August 2011, 10:48 PM   #10
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Here's a great Leech build ....

The Double Barreled Amplifier 300watt HOMEMADE - YouTube
  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 Leach Amp Clone (LEACH 150) panson_hk Solid State 32 22nd May 2014 11:25 AM
High Current Leach/leach super amp bowdown Solid State 41 2nd March 2011 02:15 PM
leach amp pics first diy project larryg Solid State 13 14th December 2004 08:36 PM
Leach amp vs super Leach amp supernet Solid State 0 21st February 2002 10:16 PM


New To Site? Need Help?

All times are GMT. The time now is 11:33 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