A LM3886 "Stasis" Power Buffer - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 22nd April 2005, 05:01 PM   #1
diyAudio Member
Join Date: May 2005
Location: TN
Default A LM3886 "Stasis" Power Buffer

Only for the little that go across the border inverting OPamp and non- inverting, my complete cookies.
This configurations don't see easily in the forum, because anyone has the abilities to develop usually uses it for money. I hope that some is able draw an advantage. The draw is 2 schemes. Schemes first are a circuit that I have built "the flight" to do some test, and I have thought that were able be of interest to some beginner. In practice this is an OPamp shaped in Tracking, or in degree to develop a range of tension in exit much more tall, on account of the V power floting. The second circuit is that more original. Trade of a Power current/current converter, that is it may use as buffer (unit gain) for audio circuits to ample swing. if it connects directly, without insert it in the negative feedback , himself you produce a "Stasis" amplifier. This technique has been invented and patented by Nelson Pass, and second-hand commercially. In practice, this special type of buffer "sense" the current to the load from the amplifier of tension, and from it amplifies the value, but without influence on the performances. If they use this buffer with preampli to valves to ample swing, or to discrete in class A to the results can be exceptional. For a fast evaluation, it may use the Tracking circuit enclosure. To do it works at the best the buffer, suggestion to using a Voltage amp. with Zout<10 ohms and output current +-50mA. the more experts are able modify the parameters of the buffer using the formulae take root. I hope that some does a favor to publish to forum a " Hi-end "drive circuit. I creed to have done broadly my part, and withdraw me.

Ciao and good work

Mauro Penasa
Attached Files
File Type: pdf cc_driver.pdf (16.8 KB, 2183 views)
  Reply With Quote
Old 22nd April 2005, 06:05 PM   #2
homer09 is offline homer09  Canada
diyAudio Member
homer09's Avatar
Join Date: Jan 2004
Location: Montreal
mauro, i think its really amazing that you contribute this completely new and radical implimentations of the national chips. i just wish i had close to enough understanding to even be able to understand what you're talking about.

maybe your ideas will eventually trickle down into future PCB kits that i could understand a little better.

thanks mauro.
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote
Old 22nd April 2005, 07:00 PM   #3
diyAudio Member
Russ White's Avatar
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
Default Thanks!

More weekend schematic rading for me! Great stuff Mauro!! Keep it coming.
  Reply With Quote
Old 23rd April 2005, 12:39 AM   #4
diyAudio Member
apassgear's Avatar
Join Date: Nov 2002
Location: Vińa del Mar, Torreon
It looks great Mauro!!! Stasis always sounds interesting and intriguing to me but have not built anything similar to have an opinion on it.
Would love to see others follow this road and maybe some PCB for the circuit and I might give it a try.

Did not quite understand what you said regarding the buffer and the use of a pre with this circuit, could you explain in other words?

  Reply With Quote
Old 23rd April 2005, 03:02 AM   #5
diyAudio Moderator Emeritus
lumanauw's Avatar
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Hi, Mauro,

Nice designs

This technique has been invented and patented by Nelson Pass
Sorry, I still dont get it. Which patent? Or which Statis does it related to?
  Reply With Quote
Old 23rd April 2005, 06:45 AM   #6
Electrons are yellow and more is better!
diyAudio Member
peranders's Avatar
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
maupenas, good idea but LM3875 can't be used for this purpose because it isn't stable for gains less than 10. Have you tested your idea in real life?
/Per-Anders (my first name) or P-A as my friends call me
PA03 LM4780 amplifier group buy, SIGN UP HERE for the group buy 0 boards left. 118 paid.
  Reply With Quote
Old 23rd April 2005, 07:26 AM   #7
diyAudio Moderator Emeritus
lumanauw's Avatar
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
maupenas, good idea but LM3875 can't be used for this purpose because it isn't stable for gains less than 10. Have you tested your idea in real life?
The voltage gain maybe 1 (voltage buffer). But the current gain in right schematic is 100/0.1ohm=1000x. Is this making chipamp unstable?

Does this kind of "Current Amplifier" suitable for driving ordinary speakers (which is designed for voltage source amplifiers)?
  Reply With Quote
Old 23rd April 2005, 07:32 AM   #8
diyAudio Member
Join Date: Aug 2003
Location: Prague,Czech Republic
So called " Stasis stage " use floating rails in power stage, not in VAS. With LM .... is this method used in professional active boxes, for example in one small box from firm KV2Audio.
  Reply With Quote
Old 23rd April 2005, 08:28 AM   #9
diyAudio Member
leadbelly's Avatar
Join Date: Dec 2002
Location: Calgary, Alberta
Grazie Mauro!

I've been very interested in current drive and varying output impedance with LM chips ever since reading about it on Rod Elliot's site and of course all the hype with FirstWatt. Now here is something detailed to chase!
The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts. Bertrand Russell
  Reply With Quote
Old 23rd April 2005, 11:43 AM   #10
diyAudio Member
Join Date: May 2005
Location: TN
Various precise statements:
The "stasis" brevet is operational after 1978 and is in use by Threshold.
My scheme has not commercial intentions and then it is can make a will.
Datum that the "Stasis" idea is not mine, and it is broadly divulged by Pass, not time perderoes to describe it in the detail. The circuit that I have proposeded is not a "normal" buffer to unit gain voltage, but a current/current converter with input connected directly to the exit.
the Voltage amplifier that it connects to the input furnishes a tide directly to the load, but for effect of the bridge it "sees" a load with 1000 times + tall (our case) in comparison with that reality.
Datum that the circuit of tide is external a the Neg. feedback of the voltage driver amplifier, produces to all the effects the "stasis" mechanism ( is not a hypothesis,it is a certainty ). If they measure the distortion of the circuit discover that is equivalent perfectly to that of the Voltage stadium. The fact that Threshold has always used this technique with "current mirrors" and with discrete components, change the medium. If then some shows me that get it same effects of "Stasis" without respect from it the parameters, means that have invented a new system and I am able patent it.
I don't know other applications as this ( Threshold to depart ) but even for effect of the brevet, I doubt that other builders have used it.
For what concerns the doubts concern to the stability, for fortune sees that some expert takes part in explain ( better than my)
the dynamics of operation. I never don't expose circuits that doesn't work well, because this circuits have been make a will in laboratory on real prototypes. If have good bases of electronics, discover that my nets never are not banal, and itis able help you even for Your projects. in this particular case, the stability is guaranteed by R8 and C1, that I am not optional, but it creates of the pole/zero conjugated with the rest of the bridge and make it stable. this technique is second-hand ( a few ) to stabilize "on external" the no-compensateds OPamp, as LM3875 and LM3886 ( still more unstable ) and the point of work is calibrated on the prototype.

For the beginners:
For Voltage stadium I intend an amplifier to discrete or OPamp that produces the necessary voltage-gain to drive the loudspeakers ( es. 1Vin > 20Vout). If they connect my buffer to your pre-amplifier, works all well but they don't succeed to have a greater power of 5-10W. to get an amplifier in "stasis" has to build an pre-amplifier In degree to produce a voltage swing about 30Vpp and Zout<10ohm, capable of output current furnish with at least 20-50mA.
It may use a tracking circuit as what I have proposeded or other technology, as the valves circuits, or the Mosfet circuits of Pass. The output distortion and the general sound are that of the driver.


  Reply With Quote


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
What Does Fostex "Rated Input" and "Music Power" mark02131 Full Range 5 13th October 2012 05:18 AM
Need your opinion, how small gain can I use with LM3886 (how close to "flat amp")? danielwritesbac Chip Amps 20 30th November 2008 12:27 AM
Simplified LM3886 amp pcb "organic" style Groundloops Chip Amps 0 23rd May 2006 02:46 PM
Fostex "rated input" and "music power" hugz Full Range 12 16th March 2006 04:33 PM

New To Site? Need Help?

All times are GMT. The time now is 01:50 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2