|
Home | Forums | Rules | Articles | diyAudio Store | Blogs | Gallery | Wiki | Register | Donations | FAQ | Calendar | Search | Today's Posts | Mark Forums Read | Search |
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 |
![]() |
|
Thread Tools | Search this Thread |
![]() |
#21 | |
diyAudio Member
Join Date: Nov 2009
Location: algeria/france
|
Quote:
The subject was much discussed by Olivier73 in a thread by there. |
|
![]() |
![]() |
#22 |
diyAudio Member
Join Date: May 2003
Location: Belgium, Limburg
|
|
![]() |
![]() |
#23 | |
diyAudio Member
Join Date: Apr 2011
Location: Pretoria
|
Quote:
![]() Most MOSFET amps seems to use BJTs for temperature compensation. The Crescendo Millenium Edition is one of the few designs that uses a MOSFET. As far as I know anyway. Last edited by ingenieus; 13th October 2011 at 09:07 PM. |
|
![]() |
![]() |
#24 | |
diyAudio Member
Join Date: Apr 2011
Location: Pretoria
|
Quote:
![]() The current mirror in my post above is the solution suggested by Bob Cordell. There is a third way: http://www.diyaudio.com/forums/solid...ml#post1413451 ![]() I have to admit that I haven't figured it out yet... Last edited by ingenieus; 13th October 2011 at 09:44 PM. |
|
![]() |
![]() |
#25 | ||
diyAudio Member
Join Date: Apr 2011
Location: Pretoria
|
Quote:
Here is a SPICE model for it: Quote:
|
||
![]() |
![]() |
#26 | ||
diyAudio Member
Join Date: Nov 2009
Location: algeria/france
|
Quote:
![]() Quote:
implementation is not that trivial. Surely that Bob s solution works although that s quite a lot of complexity. Anyway , as already said , an amp dedicated to feed a subwoofer will have inherently low THD since NFB will be quite efficient at those frequencies , and a crescendo like amp , with compensation, seems to me the best option. |
||
![]() |
![]() |
#27 |
diyAudio Member
Join Date: Apr 2011
Location: Pretoria
|
I have done an LTspice simulation with an IRFBF20 in the bias stage. It does work but THD at 20kHz is significantly worse. This is not important in a sub-woofer amp, but this is a very promising circuit and further investigation might yield some answers.
|
![]() |
![]() |
#28 |
diyAudio Member
Join Date: Apr 2011
Location: Pretoria
|
FYI: the original Crescendo Millenium Edition from Elektor, April 2001.
|
![]() |
![]() |
#29 |
R.I.P.
Join Date: Jul 2004
Location: Scottish Borders
|
The output impedance of the cascoded VAS is comparatively high cf. a Follower.
Most Designers that suggest the cascode also say you must lower that output impedance by using a Follwer after it. Since there is no separate driver stage. The Crecendo is flouting those design recomendations. Even D.Self who adopts the double EF as a VAS says there are attractions to using the cascoded VAS + EF.
__________________
regards Andrew T. |
![]() |
![]() |
#30 | |
Account disabled at member's request
Join Date: May 2006
|
Quote:
Its all myth, every manufacturer looks at trying to fool potencial clients into believing some circuit part is bad and why his amp is better, one has to consider here, not necesarily better, just different. Last edited by homemodder; 14th October 2011 at 10:59 AM. |
|
![]() |
![]() |
Thread Tools | Search this Thread |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
Subwoofer Amp Design Suggestions | SpikedCola | Chip Amps | 45 | 28th February 2011 01:31 AM |
Offline SMPS duty cycle, core & bridge | JohnT_diy | Power Supplies | 10 | 16th May 2008 10:22 PM |
Advice on a 15"+ sealed subwoofer design | gwgjr31 | Subwoofers | 25 | 27th April 2006 04:18 PM |
I need help with my 30" subwoofer design | jhung1983 | Subwoofers | 11 | 13th December 2005 12:48 AM |
Just a little note : When you wideband amp oscillates at 200KHz and you dont know why | sonnya | Solid State | 6 | 1st August 2003 06:08 PM |
New To Site? | Need Help? |