Leach amp - 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 25th May 2004, 07:00 PM   #1
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
Default Leach amp

I've never heard anyone criticise the sound of the Leach amp. In fact, it seems like everything I've read about it has been positive. I've seen criticisms of some of the general features of the amp, e.g., triple darlingtons, fully complementary, old transistors, etc., but just as many positive comments about the same structural features; i.e., use of the same output transistors in the JLH amp, etc. Looking for positive/negative discussion on the amp schematic, and how it compares with other amps.
  Reply With Quote
Old 26th May 2004, 04:45 AM   #2
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
I build the Leach some years ago using original PCB's from Mr. Leach.

It was tested for app. 14 days and then scrapped again due to it's weak bass reproduction....
However I find the mid and trebble reproduction very fine, so I would maybe use it again for in an active system, but only for frq's above 100 Hz.

Please note that sound is objective to the individual person, so you may find it as the "right" amp for you....
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 26th May 2004, 06:04 AM   #3
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
hi,
i built my first leach amp in 1984, before that, in the mid to late 70's i cloned a poineer sx770 power amp, and other amps in the tiger series of Dan Meyer....

about the leach amp...it is not tiring to listen to at high levels, the amps seem to work effortlessly....mids and highs are crystal clear, bass is decent....the tigersaurus on the other hand provided a lot of puch in the low end, even with just 10kufd in the supply rails...but mids and highs are nowhere near the leach amps in clarity....i'd choose the leach over the tigersaurus anytime...
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 26th May 2004, 06:10 AM   #4
meat is offline meat  United States
diyAudio Member
 
Join Date: Jan 2004
Location: AZ
I can only get one channel working on my Leach amp. I don't like the mounting scheme of the transistors outside and all of the wires to the inside. I understand you have to keep the heat out, but a connector seems like a better option, but it may effect sound quality. There is no silkscreen on the board. Not that I could design anything better.
  Reply With Quote
Old 26th May 2004, 07:05 AM   #5
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default I was collecting my whole courage to say

And i say that very ashamed, Mr. Leach is a reference man!

But, unfortunattelly, i perceive some loss of deep bass.

Carlos
__________________
Convertion of 8 speaker output wire into standard 2 wires; https://www.youtube.com/watch?v=toZjKw3uUMo; Unbeatable!; https://www.youtube.com/watch?v=u4tGBiqMnzQ
  Reply With Quote
Old 26th May 2004, 07:58 AM   #6
diyAudio Member
 
Join Date: Mar 2001
Location: Auburn, WA (somewhere between Seattle and Tacoma)
Blog Entries: 1
Send a message via ICQ to Damon Hill
Quote:
Originally posted by meat
I can only get one channel working on my Leach amp. I don't like the mounting scheme of the transistors outside and all of the wires to the inside. I understand you have to keep the heat out, but a connector seems like a better option, but it may effect sound quality. There is no silkscreen on the board. Not that I could design anything better.
I assume you're talking about TO-3 style cases?

This amplifier works fine with the MJ21193/94 and should
work equally well with the MJL plastic case series. Haven't
tried it with the popular Toshiba transistors yet; they might
be fast enough to cause stability problems with the stock
circuit. BrianGT designed a Leach board that has the exact
hole spacing for the plastic case leads.

I'm curious about the perception of lack of deep bass, but I've
never had the chance to listen to an amplifier of similar quality
and power on my system so it's hard to comment. I need to
get out more. :/

It would be fun to compare the Leach amp against ASKA, one
of the OPTIMOS amps and some of the other popular solid
state amp projects, and some really good commercial amps.
I'm sure there's some room for improvement, maybe just
good parts tweaking.
  Reply With Quote
Old 26th May 2004, 11:21 AM   #7
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
People that don't like the bass on the Leach like ...

MUD.


What you all perceive as 'bass' is power supply mud from un-bypassed large electrolytic capacitors.

If you want your Leach to sound just like the Tigersaurus in the bass, just take out the four pieces of 22F that bypass the main rail filter caps.

If you want the Leach to sound like the Tigersaurus in the highs, just remove the 0.1F bypass from the feedback cap and add a Tantalum input coupling cap.

Want your Leach to sound like a Stasis? Move all the feedback to the feedforward point on the pre-drivers (v4.5), even with un-matched outputs the distortion will be less than 0.5% With matching you can get less than 0.05%
  Reply With Quote
Old 26th May 2004, 11:41 AM   #8
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default I have strong suspection that AKSA will be the one!

Just read entire forum and you will see who's the men.

Not only hugh, but some others too are special, some of them do not like to show themselves, " but has also ".

Some of them we love because they know they are special and take care not to say, others we hate them because special but no shy to show us, others we are tollerant because they hardly knows their quality than has no patient enough related treat our poor insignificance mortal. And others, as a computer (sorry, but only chocoholic knows what i am telling about.. and choco is not the person) ... those, make analises without no feeling going together.

I know one, that is the most precise brain in earth, sinthetic, clear and very kind... but you have to be precise with him, if not, a red lamp start to flash and a buzzer start to run:

- No register!!... bad income information!... attention.!... failure error in register!..... chocked in windows register!
Do not misunderstand, this one i like him very much, but have to be precise when you speak, this way:

- I will be happy to see the schematics!

He do not move itself, you have to say:

- Please, can you send me schematics!

He move fast and gladly.

So, more than technologies, we have to understant one each other. In my language we talk inverted related english, the small sentence;

Can I? in my language i ask I can?

So, whats real meaning.... can or cannot..... i can?, is it some kind of joke, ironic words?... there are cultural an languages problems to understand one each other.

My culture, man value, for a big part of my society, is how good he is, how patient and delicated with sons, how much time spend with family related to their own things, the tolerant way he understand the world, and how much he is not "defended" inside... those that can see error only in others and never can see their own defects and problems. Last evaluation your degre, and money you have. In a society were money is not well divided, this difference, if great, can be a "bad evaluated" person, because has 10 tv sets listening one each time. 5 cars and driven only one each time....... and, others walking.... this way, rich can have bad evaluation.

Indians teached us that we have nothing, we own nothing, we are passing some time in mother earth, ground, sand is our mother, we will return to be dust, ground, earth and some material forming plants and bacteries... how can we be the owner of something?... this feeling make us flexible... if world finishes figthing, i am sure, we will survive (Gloria Gaynor song i suppose).

Never heard AKSA, and i will not, unemployed, can not face those things, also schematic do not exists, and i suppose can be so simple you understand looking into the board 5 seconds!.... the secrets are!.... and i already discovered with kind of secrets are there. It may be the Best!.... because philosophy precise in this imprecise world, where "values" are changing a lot, adapting persons one each others... and this is profound... deep as ocean!

Carlos
__________________
Convertion of 8 speaker output wire into standard 2 wires; https://www.youtube.com/watch?v=toZjKw3uUMo; Unbeatable!; https://www.youtube.com/watch?v=u4tGBiqMnzQ
  Reply With Quote
Old 27th May 2004, 10:08 AM   #9
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
come to think of it, i have not found any other amp commercial or diy that i really liked better than a leach amp....

i repaired a lot of japanese amps as a means of livelyhood, sansui's, pioneer's and marantz and etc, but none of them comes close to a leach amp.....
__________________
the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
  Reply With Quote
Old 27th May 2004, 11:35 AM   #10
pooge is offline pooge  United States
diyAudio Member
 
Join Date: May 2003
Location: Northern Va.
I built the first Leach amp right after it appeared in Audio magazine. I took it to a friend's house and swapped it for his Dynaco SS amp that he built. I normally don't advocate making evaluations like this, but it stomped the Dynaco. Everyone in the room was amazed at the difference. I subsequently bought the version 4 boards and upgraded the parts to 4.3, but have not yet improved to 4.5. I have not had an opportunity to compare the amp with other amps since my initial build. Has anyone noticed a difference between the 4.3 and 4.5 versions, which added back the diodes in the cascode front end? BTW, the schematics of the amp are here: Leach amp schematic
  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 12:25 PM
High Current Leach/leach super amp bowdown Solid State 41 2nd March 2011 03:15 PM
anyone have leach PCB? ilyash Group Buys 2 7th September 2007 11:36 AM
Leach Superamp vs Leach 4.5 Samuel Jayaraj Solid State 4 26th October 2002 10:20 AM
Leach amp vs super Leach amp supernet Solid State 0 21st February 2002 11:16 PM


New To Site? Need Help?

All times are GMT. The time now is 11:45 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