hypex ncore - Page 404 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Vendor's Bazaar

Vendor's Bazaar Commercial Vendors large & small hawking their wares

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 17th May 2012, 11:32 AM   #4031
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Is it really possible to turn the NC400 into a transconductance amp ? I would expect stability issues, as the switching signal residual at the output would be fed back to the amp's inverting input.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 17th May 2012, 11:35 AM   #4032
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
The level of the switching signal residual will of course be attenuated by the value of the sense resistor (perhaps around 0.22 Ohm?) compared with the impedance of the load at the switching frequency.
  Reply With Quote
Old 17th May 2012, 11:42 AM   #4033
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
I'm just waiting for the first guy willing to try this ...

An other question: should not the open loop gain of the "op-amp" (the NC400 in this case) be as high as possible? The NC400 has just 26 dB of gain, while a typical op-amp chip is in the 100 dB territory.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 17th May 2012, 11:47 AM   #4034
ChrisPa is offline ChrisPa  United Kingdom
diyAudio Member
 
ChrisPa's Avatar
 
Join Date: Jan 2005
Location: Saddleworth
Quote:
Originally Posted by pos View Post
So how much watt would a NC400 be able to output in a 4/8/16 ohms load with such a feedback loop?
Choose your own Rf and do the maths

ncore is current limited to 24A max (typical) continuous (DC not RMS)
ncore load = Rload + Rf
work out total power avail (note: RMS not peak)
work out proportion of power available to Rload (and not being dissipated in Rf)

Last edited by ChrisPa; 17th May 2012 at 11:56 AM.
  Reply With Quote
Old 17th May 2012, 11:55 AM   #4035
ChrisPa is offline ChrisPa  United Kingdom
diyAudio Member
 
ChrisPa's Avatar
 
Join Date: Jan 2005
Location: Saddleworth
Quote:
Originally Posted by StigErik View Post
Is it really possible to turn the NC400 into a transconductance amp ? I would expect stability issues, as the switching signal residual at the output would be fed back to the amp's inverting input.
Surely Bruno's already done that for us?
If this were a problem wouldn't it already be a problem with the nc400 as a voltage amp?

Quote:
Originally Posted by StigErik View Post
I'm just waiting for the first guy willing to try this ...
Bruno says he already has, and it's in the Grimm LS1

Quote:
Originally Posted by StigErik View Post
An other question: should not the open loop gain of the "op-amp" (the NC400 in this case) be as high as possible? The NC400 has just 26 dB of gain, while a typical op-amp chip is in the 100 dB territory.
26dB is the closed loop gain - we need to open the loop

Section 6 of the data sheet specifies 56dB (open) loop gain (min) at 20kHz - ie. it's higher than that elsewhere,
but by inference it may be a max of 62 dB at 15kHz

Last edited by ChrisPa; 17th May 2012 at 12:09 PM. Reason: correctly format StigErik's quote
  Reply With Quote
Old 17th May 2012, 11:59 AM   #4036
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
Because the NC400 doesn't have infinite gain, then the actual output impedance will be lower than you would get in the 'text book' circuit using an ideal op-amp and a current-sense resistor.

It is a simple matter to calculate the Z(out) you will actually get for a gain block with less than infinite gain, or you could easily simulate it with one or other flavour of SPICE.
  Reply With Quote
Old 17th May 2012, 12:02 PM   #4037
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
How are you intending to open the NC400 normal NFB loop? All this talk about the O/L gain is not relevant otherwise. If you are going to add a simple current-controlled NFB loop around the amp and speaker unit then you need to use the C/L gain of the NC400 for the calculations.
  Reply With Quote
Old 17th May 2012, 12:11 PM   #4038
ChrisPa is offline ChrisPa  United Kingdom
diyAudio Member
 
ChrisPa's Avatar
 
Join Date: Jan 2005
Location: Saddleworth
Quote:
Originally Posted by Ouroboros View Post
How are you intending to open the NC400 normal NFB loop? All this talk about the O/L gain is not relevant otherwise. If you are going to add a simple current-controlled NFB loop around the amp and speaker unit then you need to use the C/L gain of the NC400 for the calculations.
Exactly - that was a question I was asking back in my original musings
  Reply With Quote
Old 17th May 2012, 12:43 PM   #4039
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Would it make any sense to turn the NC400 with its 26 dB gain into a transconductance amp, that is without making any modifications to the NC400 itself to increase the gain?

In any case we would have to sacrifice balanced input.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 17th May 2012, 01:18 PM   #4040
pos is offline pos  Europe
diyAudio Member
 
pos's Avatar
 
Join Date: Feb 2008
Location: Paris
Quote:
Originally Posted by ChrisPa View Post
Choose your own Rf and do the maths

ncore is current limited to 24A max (typical) continuous (DC not RMS)
ncore load = Rload + Rf
work out total power avail (note: RMS not peak)
work out proportion of power available to Rload (and not being dissipated in Rf)
So to me that is quite the same as putting a resistor inline with the driver? Will not Rf still be burning much of the outputted power? I don't really understand the practical difference.

in my experiment I was using a 44 ohms resistor inline with a 16 ohms driver (Re, but lets simplify). That gives a total load of 60 ohms, and only ~1/4 of the outputted power going into the driver.
My amp puts 690W into 8 ohms, so should be able to put max 100W into 60 ohms, so around 25W going into the driver itself.
With a 200W/8 ohms ncore the same logic would go down to less than 7W...

I am sure I am missing something here, though

Last edited by pos; 17th May 2012 at 01:27 PM.
  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
Hypex problem, who can help Hansms Class D 9 18th August 2013 07:49 AM
Hypex steveww Class D 14 18th November 2010 02:44 PM
Question for those who have tried hypex smps with hypex modules avian Class D 12 3rd March 2009 10:30 AM
Hypex UcD 180AD + signal wires, Power Supply ST, Hypex Transformer TR100A c10h12n2 Swap Meet 7 7th July 2007 04:55 PM
FS: Hypex UcD 400/180AD, hypex toroid Archmage Swap Meet 4 14th November 2006 05:23 AM


New To Site? Need Help?

All times are GMT. The time now is 12:31 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