Work In Progress... Leach Based Amplifier - Page 9 - 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 27th November 2013, 10:01 PM   #81
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
and don't forget, it is free for anyone to build....
__________________
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 November 2013, 10:17 PM   #82
diyAudio Member
 
Join Date: Apr 2012
Location: Florida & France
Quote:
Originally Posted by AJT View Post
and don't forget, it is free for anyone to build....
You betcha!!

And since we're all collaborating on the design and nobody is selling kits, then there is no fear of conflict of interest.

I know a lot of people out there are building the leach amp, some, like me, wish they had him as a teacher... So many have never even met the guy but are missing him! I haven't had the privilege to exchange emails with him, but I could have, if only I had known...

Marshall! We miss you!
  Reply With Quote
Old 27th November 2013, 10:28 PM   #83
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
i did exchange emails with him too...he is surely missed....
__________________
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 28th November 2013, 12:05 AM   #84
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by spookydd View Post
Have you built something like this that is not mosfet based?
Yes, quite a lot. This year only I made six different amps, last year a few, also the last one using bipolar outputs in BIGBT form.
__________________
First One VSSA
  Reply With Quote
Old 28th November 2013, 12:15 AM   #85
diyAudio Member
 
BobEllis's Avatar
 
Join Date: Sep 2003
Location: Upstate NY
Spooky, I have a separate chassis for my F5 so I will be comparing the two amps, not rebuilding my Leach.

I still think that you can do away with the INA134 and use the ground end of C12 as your negative input with a bit of fiddling with your input resistors. Saves a 15V PSU and the potential signal degradation using the INA134.
  Reply With Quote
Old 28th November 2013, 07:28 AM   #86
diyAudio Member
 
Join Date: Apr 2012
Location: Florida & France
Quote:
Originally Posted by BobEllis View Post
I still think that you can do away with the INA134 and use the ground end of C12 as your negative input with a bit of fiddling with your input resistors. Saves a 15V PSU and the potential signal degradation using the INA134.
I would like that, and I didn't do it because I wasn't sure exactly how to do this right. The input needs to easily be converted to unbalanced if need be, so that broken connection to signal ground on the negative input needs to be made right so it gets reconnected when going unbalanced. I'm not sure how to do this properly.

It would save space and several parts, without that extra psu for sure. That ina134 has rather good performance, so I wasn't too worried about its impact, however I am always in favor of having the least amount of parts in the signal's path, so obviously this qualifies.

There is one thing that I do want to be able to do though. I want to add a muting on that input, and I don't see how this can be done if we are in such a balanced arrangement. It must work either way.

I want to use a solid state input muting, avoiding relays and this circuitry needs to be easily triggered. I would make some kind of arrangement to mute the input at powerup, then the output mute is lifted first before the input, but then when powering off, the input mute should be done first.
  Reply With Quote
Old 28th November 2013, 08:19 AM   #87
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by AJT View Post
imho. "best sound quality possible" is based on personal realities and may not be good for another....
when someone praises a design as "best sound quality possible" and yet sells kits for those, i get scared....
Many people's consensus on their's subjective opinions becomes objective.

BTW I recommended other's guy design, not intended to promote anything implying on me.

It's just a shame to have a project with such high level design standards and so average sound quality.
__________________
First One VSSA
  Reply With Quote
Old 28th November 2013, 08:29 AM   #88
diyAudio Member
 
Join Date: Apr 2012
Location: Florida & France
Quote:
Originally Posted by Lazy Cat View Post
It's just a shame to have a project with such high level design standards and so average sound quality.
I don't think of the leach amp as "average" sound quality. I don't think there is something that much better out there. So I'm curious and I'd like to know what you propose. For the moment, what I've seen on the threads you mentioned, although I have yet to see it all, was all mosfet based, so that doesn't appeal to me at all. That's why I was asking about non mosfet based amps.

I'd like to take a closer look at what you're referring to and get a sense of that supposedly superior sound quality. I need to be convinced. As far as I'm concerned, I'm not using a design that's substandard, so let's compare, objectively if possible.
  Reply With Quote
Old 28th November 2013, 08:43 AM   #89
AJT is offline AJT  Philippines
diyAudio Moderator
 
AJT's Avatar
 
Join Date: May 2003
Location: Palatiw, Pasig City
Quote:
Originally Posted by Lazy Cat View Post
Many people's consensus on their's subjective opinions becomes objective.

BTW I recommended other's guy design, not intended to promote anything implying on me.

It's just a shame to have a project with such high level design standards and so average sound quality.
imho, the test of time is the verifier, will people still build your amps say 20 years from now?

the leach amp designed in the 70's and still being built even today, isn't that something?
__________________
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 28th November 2013, 09:04 AM   #90
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by AJT View Post
what is a "little obsolete" with this design?
any suggestions to improve?
Do following steps for better SQ:
- if needed use Lundahl input transformer for un/balanced input operation
- completely omit T1, T6 input cascode
- replace R5, R20 by j-fet CCS
- replace R1, R23 with zero ohm wire
- change FB network values to 2,2 k/100 Ohm/2200 uF
- change R2, R21 to 680 Ohm
- change R9, R10, R14, R15 to 22 Ohm
- change R25, R33 to 22 Ohm
- overall use of better modern transistors

There's more but for the start is OK.
__________________
First One VSSA
  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
Work in progress... Asio4All Q pcb121055 PC Based 3 25th November 2011 04:59 AM
FE167E finally ! work in progress... ow31 Full Range 27 28th June 2006 09:03 AM
progress pic MMTMM based on HIVI B3N Tazz Multi-Way 1 18th July 2005 05:03 PM
BZLS work in progress till Pass Labs 10 26th February 2004 07:34 AM
Aleph 5 - work in progress SuppersReady Pass Labs 23 14th November 2003 09:40 PM


New To Site? Need Help?

All times are GMT. The time now is 01:57 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