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

Notification

Icon
Error

Login
Resistor help: IVY max gain in multichannel setup
Options
View
Go to last post Go to first unread
Previous Topic Next Topic
opnordahl  
#1 Posted : Saturday, February 2, 2013 7:51:55 PM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
I am going to use 4 IVYs connected directly to poweramps (balanced input of 6 Hypex NCORE and 2 Ucd700). For 6 of the channels I plan to use 4 VRMS output. However for two of the last channels I need more gain. The IVYs are connected to one Buffalo II (2 channels) and one Buffalo III (2 + 4 channels). The I2S source is the ExaU2I.

For the IVYs connected to Buffalo III i plan the following:
2+2 channel with no channels combined:. Wanted output: 4 VRMS
Values for resistors: R1-4 = 3kOhm, R13-16 = 356ohm
Are these resistor values correct?

For the last two channels from the Buffalo III I am planning to combine two channel pairs into two channels.
However I need more gain than 4 VRMS. What is the maximum recommended gain I can get from the IVY?
If I want 8 VRMS output are the following resistor values correct to use?
R1-4 = 1.5kOhm, R13-16 = 750Ohm.

Edited by user Saturday, February 2, 2013 8:13:56 PM(UTC)  | Reason: Not specified
Back to top

Wanna join the discussion?! Login to your Twisted Pear Audio Support forum accountor Register a new forum account.
Back to top  
Russ White  
#2 Posted : Sunday, February 3, 2013 2:38:37 AM(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)
To get 4VRMs you need only double R13-R16. No other changes.

I wouldn't try to get more than maybe 6VRMs. Above that and the THD+N will really suffer.

You could try 499R at R13-R16 and see if that gets you where you want to be.
Back to top
WWW
opnordahl  
#3 Posted : Sunday, February 3, 2013 2:38:07 PM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
Thank you very much Russ.

I assume you approve the values I have chosen for R1-4 in my setup.
Back to top
Russ White  
#4 Posted : Sunday, February 3, 2013 3:58:15 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)
No - do not increase R1-4. That stage would clip for sure. Only make R13-R16 356R and you have ~4VRMs.

Edited by user Sunday, February 3, 2013 3:59:20 PM(UTC)  | Reason: Not specified
Back to top
WWW
opnordahl  
#5 Posted : Sunday, February 3, 2013 7:14:40 PM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
Maybe I have really misunderstood something but the Buffalo III Integration guide clearly states that the IVYIII value for R1-4 needs to be changed when more than 2 outputs from the Buffalo III board are used.

The calculation in the guide states: R=3000/amount of parallel output channels og Buffalo III

In my example I am planing to not combine any parallel output channels for two channel pairs (2+2)

R1-4=3000/1 = 3kOhm

For the last two channels I am planning to combine two parallel output channels into one

R1-4=3000/2 = 1.5kOhm

What am I missing?

Edited by user Sunday, February 3, 2013 7:16:14 PM(UTC)  | Reason: Not specified
Back to top
Russ White  
#6 Posted : Sunday, February 3, 2013 10:51:44 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)
I may have missed something not you. :)

Still I would prefer to add the gain at the second stage.
Back to top
WWW
opnordahl  
#7 Posted : Monday, February 4, 2013 10:53:15 AM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
Do you have any suggestions for R values for IVYIII in both cases using the BIII then?

Case 1: Not to combine any parallel output channels from the BIII. Output = 4RMS

Case 2: Combine two parallel output channels from the BIII. Output = 4RMS or more if advisable

Edited by user Monday, February 4, 2013 5:10:01 PM(UTC)  | Reason: Not specified
Back to top
Russ White  
#8 Posted : Wednesday, February 6, 2013 1:19:44 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)
I have not forgotten about you.

I am doing some simulation to determine a good set of resistors for your application.
Back to top
WWW
opnordahl  
#9 Posted : Thursday, February 7, 2013 10:47:46 PM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
Thank you. I am a bit at a loss here...
Back to top
opnordahl  
#10 Posted : Thursday, February 14, 2013 8:25:35 PM(UTC)
opnordahl

Rank: Member

Groups: Member
Joined: 1/31/2009(UTC)
Posts: 18
Location: Norway
Originally Posted by: Russ White Go to Quoted Post
I have not forgotten about you.

I am doing some simulation to determine a good set of resistors for your application.


Hi Russ,

I have done some tests with my speakers and 4vrms will do for all channels. I also have the option of increasing the gain slightly with the Hypex power amps.

According to your simulations do I already push the IVYs too much with 4vrms for case 1 and 2 mentioned above?
Which resistor combination gives the lowest SNR?
Back to top
Rss Feed  Atom Feed
Users browsing this topic
GuestUser
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.

Youtube
Copyright © Twisted Pear Audio