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

Solid State Talk all about solid state amplification.

The AMNESIS amp: a good amplifier, like a gentleman, has no memory.
The AMNESIS amp: a good amplifier, like a gentleman, has no memory.
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 12th June 2019, 05:52 PM   #621
indra1 is offline indra1  Indonesia
diyAudio Member
 
Join Date: Nov 2010
Location: Bogor
Quote:
Originally Posted by N101N View Post
Those are veritable V-FETs (SIT) all right, very valuable, except the Tokin parts that are not in the same class.
Would you take a look at this please:

http://www.amplimos.it/images/hiraga2_Vfet.gif
I'd like to warn that the circuit has a fatal failure mode close to clipping due to output VFET cross conduction. Please avoid at all cost.
  Reply With Quote
Old 12th June 2019, 10:17 PM   #622
N101N is offline N101N
diyAudio Member
 
Join Date: May 2018
Cross conduction is one of many confusedly used notions. Instead, keep in mind that static induction transistors do not constitue a light load. The grounded emitter drivers must be selected and biased with great care and the appropriate choices are few.
  Reply With Quote
Old 12th June 2019, 10:33 PM   #623
gaetan8888 is offline gaetan8888  Canada
diyAudio Member
 
Join Date: Apr 2007
Hello

In input the stages and the VAS most memory distortion is caused by changes in Vce. Thus a low-gain amp with high input voltage would have more memory than a high-gain amp with low input voltage. One simple way to reduce memory distortion distortion is to use transistors with larger dies, having higher thermal mass, how about ksc3503 or ksc1381 ? I have lot of them, they may need a bit more current from the ccs.

Any thought or ideas about that ?

Thank

Bye

Gaetan

Last edited by gaetan8888; 12th June 2019 at 10:39 PM.
  Reply With Quote
Old 12th June 2019, 10:58 PM   #624
N101N is offline N101N
diyAudio Member
 
Join Date: May 2018
I have got thoughts or ideas. I entirely dismiss your assumptions on memory distortion. Those Korean fakes are worthless.
  Reply With Quote
Old 13th June 2019, 12:44 AM   #625
indra1 is offline indra1  Indonesia
diyAudio Member
 
Join Date: Nov 2010
Location: Bogor
Quote:
Originally Posted by N101N View Post
Cross conduction is one of many confusedly used notions. ...
What I meant was both SIT will conduct and self destruct on output close to clipping.
  Reply With Quote
Old 13th June 2019, 03:07 AM   #626
N101N is offline N101N
diyAudio Member
 
Join Date: May 2018
Cross conduction plagues enhancement-mode switching MOSFETs in synchronous buck converters. Firstly, keep the rail voltages at a decent level. Have you built the amp according to the schematic diagram?
  Reply With Quote
Old 13th June 2019, 03:52 PM   #627
maxlorenz is offline maxlorenz  Chile
diyAudio Member
 
maxlorenz's Avatar
 
Join Date: Oct 2003
Location: osorno , Chile
Quote:
Originally Posted by gaetan8888 View Post
Hello

In input the stages and the VAS most memory distortion is caused by changes in Vce. Thus a low-gain amp with high input voltage would have more memory than a high-gain amp with low input voltage. One simple way to reduce memory distortion distortion is to use transistors with larger dies, having higher thermal mass, how about ksc3503 or ksc1381 ? I have lot of them, they may need a bit more current from the ccs.

Any thought or ideas about that ?

Thank

Bye

Gaetan
It should be easy to test. Watch for pinout config.
Bigger mass usually means bigger capacitance, right? Not a good thing...

On the other hand, one could flip over the schematics to use N JFETs as input: Hepha´stos found that KS30 had the best behaviour of all tested devices (30 years ago, it seems) in relation to MD. It has low gain, though...

Cheers,
M.
__________________
https://youtu.be/tcXg9t24JFA
  Reply With Quote
Old 14th June 2019, 12:25 PM   #628
maxlorenz is offline maxlorenz  Chile
diyAudio Member
 
maxlorenz's Avatar
 
Join Date: Oct 2003
Location: osorno , Chile
Two news, one bad and one good:

The bad, one the four channels of Amnesis started oscillating yesterday, as I heard funny "AM radio-like" noises when music stopped, and it got hot. I went back to my 200W light-bulb power cable (the improved DIY cable does clean the picture a lot) and it has behaved today.
I cannot really test it but I will try one or two ideas as soon as the weather improves: coil between amp sections; LEDs instead of Zeners for Vref of the bootstraps.

I believe a two section amp cannot oscillate right?
Mine never did...
That is a good way to try the LTMD input mod. I have been willing to mod my J2 clon but it would be too difficult to dismantle...


The good one is that my 26AWG gold plated OCC copper enamelled wire arrived. I think I can make a 50cm interconnect with it. After listening tests, I will have to decide if a need to double the strands.
I have an appetite for gold these days...



Cheers,
M.
__________________
https://youtu.be/tcXg9t24JFA
  Reply With Quote
Old 14th June 2019, 02:10 PM   #629
indra1 is offline indra1  Indonesia
diyAudio Member
 
Join Date: Nov 2010
Location: Bogor
Quote:
Originally Posted by N101N View Post
... Firstly, keep the rail voltages at a decent level. Have you built the amp according to the schematic diagram?
I consider everyone in this thread sufficiently warned. I have no need to sacrifice my vfets.

Last edited by indra1; 14th June 2019 at 02:13 PM.
  Reply With Quote
Old 14th June 2019, 08:48 PM   #630
maxlorenz is offline maxlorenz  Chile
diyAudio Member
 
maxlorenz's Avatar
 
Join Date: Oct 2003
Location: osorno , Chile
Quote:
Originally Posted by indra1 View Post
I consider everyone in this thread sufficiently warned. I have no need to sacrifice my vfets.
Vfets seem to be quite resilient...at least the industrial type should be.

What do you think about a bootstrapped VFET output, like in the SONY TA-N7?

Cheers,
M.
Attached Images
File Type: png AMNESIS BOOTSTRAPPED VFET OUT.png (50.4 KB, 71 views)
__________________
https://youtu.be/tcXg9t24JFA
  Reply With Quote

Reply


The AMNESIS amp: a good amplifier, like a gentleman, has no memory.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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
new memory for PC AndrewT Everything Else 36 24th October 2015 10:09 AM
down the memory hole? tomtt Everything Else 16 9th September 2014 01:27 PM
My memory is failing me I think?? Moondog55 Analogue Source 3 31st January 2011 03:57 AM
LCR and of course Memory Resistor impsick Parts 2 3rd May 2008 08:30 AM
Notebook Memory eag Swap Meet 4 24th April 2006 04:20 AM


New To Site? Need Help?

All times are GMT. The time now is 08:06 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki