Current conveyor as a voltage amplifier - Page 8 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

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

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 December 2012, 11:17 AM   #71
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Default practical implementation

My Lineamp is ready to be build and tried in my system.
I made three different schematic, but I will try one of them. All three simulate very similar but I will make this one to see how it sounds.
Here is PCB layout I am going to make. Any suggestion for improvement is appreciated.
Distortion(simulated) is very low and here is FFT for 20kHz and at 3.2 v p2p.
dado
Attached Images
File Type: jpg GainWire-new.jpg (227.3 KB, 183 views)
File Type: jpg GainWire-2SA-2SC-JFET.LAY].jpg (184.9 KB, 180 views)
File Type: jpg GainWire-FFT20kHz.jpg (163.6 KB, 154 views)
  Reply With Quote
Old 27th December 2012, 11:24 AM   #72
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Here are two more schematics, one for low voltage and very similar distortion pattern. Very important thing(in my opinion) is uniform distortion throughout whole bandwidth. With my first version, I hope I can drive 300 ohm headphones with easy(even with 30 ohm it is quite good with some more distortion).
dado
Attached Images
File Type: jpg GainWire.jpg (237.1 KB, 168 views)
File Type: jpg GainWire-lowvoltage.jpg (209.8 KB, 164 views)
  Reply With Quote
Old 27th December 2012, 12:33 PM   #73
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
Why are you using the A970/C2240? These will in all likelihood mess up those low THD figures. Use the OnSemi BC327/337 (if not, the BC5xx). I've proven these transistors to have good low-Vce behavior. Q1/2/5/7/9/10 (first schematic) all need to be low-quasisat types.
  Reply With Quote
Old 27th December 2012, 01:21 PM   #74
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by keantoken View Post
Why are you using the A970/C2240? These will in all likelihood mess up those low THD figures. Use the OnSemi BC327/337 (if not, the BC5xx). I've proven these transistors to have good low-Vce behavior. Q1/2/5/7/9/10 (first schematic) all need to be low-quasisat types.
Because I have those transistors at home, latter I could order the types you suggested.
Could you suggest from were to order.
I am curious whay you do not like A970/C2240, I have good experiance with them??
dado
  Reply With Quote
Old 27th December 2012, 01:37 PM   #75
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
It's not that I don't like them, they just are not right for the application. High-voltage transistors typically do bad at low-Vce. Thus it is a good idea to always avoid high-voltage BJTs in current mirrors. The BC327/337 have low internal resistance and great Vcesat behavior (the OnSemi ones did, but not NXP IIRC, haven't tested Fairchild but I would think they are okay). Thus they are pretty much perfect for a current mirror. The SMD dual versions would be perfect. Furthermore I have measured a number of BC series transistors and they are mostly matched within 300uV IIRC (this was for BC560C). A smaller test with the BC3x7 suggested they are no different.

The A970/C2240 have relatively good Vcesat behavior, but I would rather use them where they work best, in input stages.

Last edited by keantoken; 27th December 2012 at 01:41 PM.
  Reply With Quote
Old 27th December 2012, 04:30 PM   #76
Account disabled at member's request
 
Join Date: May 2006
Why is q9 and q10 connected that way ??, I thought of asking earlier. In sims of one of my power amps which uses super pair as vas, distortion is worse and after having it measured the sim results are confirmed.
  Reply With Quote
Old 27th December 2012, 04:51 PM   #77
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
It is supposed to improve PSRR. Edmund uses a similar technique in his Super TIS. It conserves the rail-modulated currents through the 150k resistors, and combines them so they cancel. I seem to recall that in the original configuration, asymmetric rail variations would cause higher PSRR than normal. Forcing the 150k resistor current to flow through both loops caused asymmetric PSRR to improve. But I also seem to recall there were some innocent gaffes made on that part of the circuit that got corrected later.
  Reply With Quote
Old 27th December 2012, 07:10 PM   #78
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
I couldn't explain better, it was Kean suggestion.
  Reply With Quote
Old 27th December 2012, 07:36 PM   #79
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Kean, when I change a970/c2240 for BC550/560 on the the positions you suggested I've got 14dB higher THD20k simulation then, but still with benign harmonic distribution. It could be that BC transistors(Cordell's models) are more realistic.
dado
  Reply With Quote
Old 27th December 2012, 07:43 PM   #80
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Blog Entries: 2
Probably. I don't have any models for those transistors, because I've tested the models and found they are not anything like the real devices. In simulation it is better to use an inferior part with an accurate model, than to use a superior part with an inferior model. Else you'll just mislead yourself and anyone who trusts your skill.
  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
The InSense Current Conveyor bcarso Digital Source 17 20th August 2012 09:11 AM
An inverting current conveyor approach bcarso Digital Source 0 30th July 2012 06:12 PM
High voltage, low current output stage for class D amplifier ionomolo Class D 45 15th February 2011 06:03 PM
voltage vs current Raj1 Solid State 1 12th June 2004 05:35 AM


New To Site? Need Help?

All times are GMT. The time now is 12:35 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