Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

AKSA's Lender Preamp with 40Vpp Output
AKSA's Lender Preamp with 40Vpp Output
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 9th November 2017, 06:57 AM   #11
Ultima Thule is offline Ultima Thule  Europe
diyAudio Member
 
Ultima Thule's Avatar
 
Join Date: Jan 2004
Location: PKS, Finland
Beutiful result!
Can someone explain why we choose P devices in the IPS?
I asked same question 3 days ago under the link below where a similar schematics was presented by Zen Mod (~4 posts above mine), but no answer yet.
About possible Babelfish J interest
  Reply With Quote
Old 9th November 2017, 07:04 AM   #12
Nico Ras is offline Nico Ras  South Africa
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
So the output is 7mW, what will you do with that?
__________________
Kindest regards
Nico
  Reply With Quote
Old 9th November 2017, 07:22 AM   #13
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Output is low impedance (<5R), but limited to 12mA CCS. This can nicely drive a small output stage, single ended or PP. The buffer, Q4, could be made a FET or even increase current to 30mA. That would boogie!

UT, if you use pnp for the LTP, it mandates npn VAS, and my experience is that npn VAS has lower parasitics and greater GBW than pnp in the same role.

HD
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com

Last edited by AKSA; 9th November 2017 at 07:33 AM.
  Reply With Quote
Old 9th November 2017, 10:42 AM   #14
Samuel Jayaraj is offline Samuel Jayaraj  India
diyAudio Member
 
Join Date: May 2001
Location: Bangalore, India
Also generally PNP in LTP gives lower current noise, doesn't it? Reason why a lot of phono preamps were designed that way. Not sure if it matters here with signal levels involved. Ofcourse, as Hugh said, it also allows for NPN VAS which is just what you want for its desired characteristics.
__________________
Sam
  Reply With Quote
Old 9th November 2017, 11:01 AM   #15
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
I do not think it would be audible, but why is there that ninth of some 0.002%?? The 9th is usually 110 - 130 dB below the fundamental. Just curious where it is created.
  Reply With Quote
Old 9th November 2017, 12:14 PM   #16
juma is offline juma  Germany
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Berlin
Quote:
Originally Posted by PMA View Post
...why is there that ninth ...
Yes, and the 5th is way too high - maybe some measuring setup artifact ?

Using PNP LTP in single rail PSU circuit is good for the PSRR too.

Anyway I'd lose Q4 and unstrangle Q3, let the LTP breathe, change CCS and at least bootstrap the tail of of the LTP. Gain should be higher so that weaker sources and/or quieter recordings can bring enough voltage swing at the output. Drive capability should stay about the same.

Roughly, something like this (R1/R2 divider might need some adjusting to ensure symmetrical clipping and freq.compensation should be checked in vivo. Practical details like PSU bypassing and similar are logical addition) :
Attached Images
File Type: gif LeMo.gif (9.8 KB, 2047 views)
__________________
Please don't use private messages for question related to audio projects. It defeats the purpose of the forum.

Last edited by juma; 9th November 2017 at 12:24 PM.
  Reply With Quote
Old 9th November 2017, 12:29 PM   #17
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
AKSA's Lender Preamp with 40Vpp Output
I'm wondering where the 5th and 9th are from too as not in sim. I should change audio interface and PC to see if it clears up.

Juma, thank you for the suggested schematic. I don't believe it is the same topology anymore though. Have you simulated it yet? Looks interesting. It could be a headphone amp with a larger C2 and higher bias, as could Aksa' circuit.

AKSA's Lender Preamp with 40Vpp Output-lemo-gif

Quote:
...if you use pnp for the LTP, it mandates npn VAS, and my experience is that npn VAS has lower parasitics and greater GBW than pnp in the same role.
This now seems perfectly clear and a great reason. I have wondered myself.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio

Last edited by xrk971; 9th November 2017 at 12:47 PM.
  Reply With Quote
Old 9th November 2017, 12:47 PM   #18
juma is offline juma  Germany
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Berlin
Quote:
Originally Posted by xrk971 View Post
... Have you simulated it yet? ...
Sorry but no, I only built it. Yes, I know that these days simulation is more valuable than the real build but I'm an old-fashioned guy...
Actually, that sch. is part of the power amp I made some time ago (imagine one pair of Lateral MOSFETs added at the output, with one LED between the Gates to bias them).
__________________
Please don't use private messages for question related to audio projects. It defeats the purpose of the forum.
  Reply With Quote
Old 9th November 2017, 02:25 PM   #19
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
AKSA's Lender Preamp with 40Vpp Output
I looked at a similar topology many years ago but never built it (yet) TGM4 amplifier

However, what is shown in post#1 is not quite the Lender circuit. The original circuit, 'invented' by Rudolph Lender when he was at Motorola uses a different arrangement with two transistors. I do remember asking Hugh about it too...

Quote:
Originally Posted by AKSA View Post
Gareth,

Tried the Lender, simulated it also. No OLG advantage over a single ended drive to a stock common emitter VAS, and no discernible advantage sonically. However, it does combine some elements of CM, tending to force current balance in the LTP by adjusting VAS current. But this may not be very useful if the VAS current is fixed anyways, as it normally is.

Cheers,

Hugh
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 9th November 2017, 02:33 PM   #20
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
AKSA's Lender Preamp with 40Vpp Output
Quote:
Originally Posted by Bigun View Post
I looked at a similar topology many years ago but never built it (yet)...

However, what is shown in post#1 is not quite the Lender circuit. The original circuit, 'invented' by Rudolph Lender when he was at Motorola uses a different arrangement with two transistors. I do remember asking Hugh about it too...
Agreed, hence which is why I said "inspired by" Lender. Nice amp design the TGM4, what does TGM stand for?
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio

Last edited by xrk971; 9th November 2017 at 02:38 PM.
  Reply With Quote

Reply


AKSA's Lender Preamp with 40Vpp OutputHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: AKSA GK-1 (EL) Preamp kit kv2 Swap Meet 1 14th April 2017 11:04 AM
Alternative output transistors for the Baby AKSA 55 cs Solid State 10 13th September 2013 10:06 AM
preamp for aksa 55 Professor smith AKSA 98 12th February 2012 12:11 AM
Borbely-Lender True Symmetry steph_tsf Solid State 33 23rd August 2011 12:52 PM
Aksa preamp? rick57 Solid State 11 19th May 2006 09:26 PM


New To Site? Need Help?

All times are GMT. The time now is 12:47 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki