Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error

Login


Options
View
Go to last post Go to first unread
deepc0re  
#1 Posted : Monday, January 16, 2012 2:58:17 PM(UTC)
deepc0re

Rank: Member

Groups: Member
Joined: 1/16/2012(UTC)
Posts: 8
Location: Norway

Hello,

Is it normal to have 9.290 VDC common mode DC bias (on the on - the and + relative to the GND) on the balanced outputs?

Is there any way to get this lower?
Russ White  
#2 Posted : Monday, January 16, 2012 3:50:03 PM(UTC)
Russ White

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN

Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
Yes, it is normal. Yes you can AC couple.
deepc0re  
#3 Posted : Monday, January 16, 2012 3:52:21 PM(UTC)
deepc0re

Rank: Member

Groups: Member
Joined: 1/16/2012(UTC)
Posts: 8
Location: Norway

Russ White wrote:
Yes, it is normal. Yes you can AC couple.


What caps do you recommend? Will I loose much sound quality ?

Im using Hypex nCore amplifiers. It will handle common mode DC, but 8-9VDC will probably clip the input stage before the amp. Will it help if I don't use GND and only - / + ? Or is the best way to use capacitors on the output?

Edited by user Tuesday, January 17, 2012 7:01:41 AM(UTC)  | Reason: Not specified

steinholien  
#4 Posted : Wednesday, January 18, 2012 9:04:25 AM(UTC)
steinholien

Rank: Advanced Member

Groups: Member
Joined: 6/12/2008(UTC)
Posts: 79
Location: Norway

As far as I can see from the datasheet from Hypex (NC400), it is a fully differential design. Ground is no part of the audiopath. My guess is that only connecting + and - should work.
deepc0re  
#5 Posted : Wednesday, January 18, 2012 11:13:03 AM(UTC)
deepc0re

Rank: Member

Groups: Member
Joined: 1/16/2012(UTC)
Posts: 8
Location: Norway

steinholien wrote:
As far as I can see from the datasheet from Hypex (NC400), it is a fully differential design. Ground is no part of the audiopath. My guess is that only connecting + and - should work.


Thanks Stein!
elviz  
#6 Posted : Tuesday, January 24, 2012 12:21:57 PM(UTC)
elviz

Rank: Member

Groups: Member
Joined: 3/29/2009(UTC)
Posts: 52
Location: Finland

Well, is it after all? If you look at the nc400 datasheet with a magnifying glass, you'll notice that the incoming signal ground is connected to the chassis, same as the nc400 signal ground. So those two things are connected.

I'd like to know the cap values as well. I tried to search the forum with no luck. Can't find the Legato 2 manual or bom either. Everyone is talking about them caps, but no one reveals the values.
steinholien  
#7 Posted : Tuesday, January 24, 2012 4:59:42 PM(UTC)
steinholien

Rank: Advanced Member

Groups: Member
Joined: 6/12/2008(UTC)
Posts: 79
Location: Norway

The best way to get a reliable answer on the need for caps, would be to contact Hypex.

To calculate capacitor value you can check this calculator: http://www.v-cap.com/cou...capacitor-calculator.php

They use this formula:

C=1/(2*pi*fc*ZL) where C is cap value in F, fc is cornerfrequency and ZL is load impedance (input impedance of poweramp).

elviz  
#8 Posted : Tuesday, January 24, 2012 5:20:32 PM(UTC)
elviz

Rank: Member

Groups: Member
Joined: 3/29/2009(UTC)
Posts: 52
Location: Finland

Thanks! That clears things out. So, i need to put the caps into the amp then. I thought i needed to implement an universal solution to remove the DC from the legato output with caps.
Rss Feed  Atom Feed
Users browsing this topic
GuestUser (4)
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.