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Hercules  
#1 Posted : Monday, January 10, 2011 12:02:03 AM(UTC)
Hercules

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Joined: 4/16/2009(UTC)
Posts: 56
Location: Hong Kong
Hi Russ and Brian, I made my own Ventus2 and sharing with Head-Fier in HK, they like it very much, and my friend would like to me to build one for him. So I'm going to order Ventus and Bi-Polar PS very soon if the configuration once decided.

The new Ventus he would like to drive mainly High-Impedance Can from 250 Ohm to 600 Ohm (Also AKG K-1000), and sometimes low impedence portable ear monitor from 32 to 120 ohm, also as pre-ampilifer for line level sources, all in single-ended connection. The volume control and source selection by Tentlabs volume control module, 64 steps volume control with 4 input and 1 output port. http://www.tentlabs.com/Components/page31/page31.html
connection as section 4 here
http://www.tentlabs.com/Compone...Note_V0_AN07_19_6_10.pdf

And He would like to made as much swing as possible without worry and re-work of the Ventus with difference headphone he purchased in future as he have no DIY skill, he would like I setup the Ventus for him plug and play, without sending me back to setup again.

And one Bi-Polar Supply will serving one Ventus board (one channel), +/- 18V rail with 2 x 30VA 18VAC transformer (+/- 15V and +/-18V tested at my setup, +/- 18V perform better on AKG K-1000)

Questions:

Powering Options

Q1. Does the Ventus2 current requirement varying with the load impedance of difference headphones plugged in, also impedance changing with frequency? If I use Shunt Type like Placid BP, how to decide the amount of shunted current at idle without making too much heat, and not hurting performance when current requirement suddenly raise? From Placid Manual, seems +/- 15V recommended, so +/- 18V not recommended?

Or LCBPS is better option here?

Gain Setting

Q2. If an external switch on the panel will be install to set gain for low-high impedance headphone and Pre-amplifier Line driver, by switch R3 between 2 set of resistors, what's the value you will recommended for Low and High imp Headphone and Pre-Amplifier? If R5 remain as 2K.

Input impedance:

Q3: Input from normal consumer line level source of SACD player, CD Player, and DAC with single-ended connection, Tentlabs volume control module placed in front of the Ventus input, what's R4 value recommended, or leave it open?

From Tentlabs website Specification:
Input impedance: > 40 k-ohm (actual value depends on volume setting)
Output impedance: < 8 k-ohm (actual value depends on volume setting)

Grounding
Q4: Should the Chassis grounded to IEC inlet grounding lug?

LME49600

Q5: What's the BW mode of LME49600 in Ventus kit?


Thanks for the advise! and any ideas can further improve the current usage and setting would be much appreciated!!



Edited by user Monday, January 10, 2011 12:42:41 AM(UTC)  | Reason: Not specified
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Russ White  
#2 Posted : Thursday, January 13, 2011 1:01:19 PM(UTC)
Russ White

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

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Was thanked: 89 time(s) in 83 post(s)
Hercules wrote:
Hi Russ and Brian, I made my own Ventus2 and sharing with Head-Fier in HK, they like it very much, and my friend would like to me to build one for him. So I'm going to order Ventus and Bi-Polar PS very soon if the configuration once decided.

The new Ventus he would like to drive mainly High-Impedance Can from 250 Ohm to 600 Ohm (Also AKG K-1000), and sometimes low impedence portable ear monitor from 32 to 120 ohm, also as pre-ampilifer for line level sources, all in single-ended connection. The volume control and source selection by Tentlabs volume control module, 64 steps volume control with 4 input and 1 output port. http://www.tentlabs.com/Components/page31/page31.html
connection as section 4 here
http://www.tentlabs.com/Compone...Note_V0_AN07_19_6_10.pdf

And He would like to made as much swing as possible without worry and re-work of the Ventus with difference headphone he purchased in future as he have no DIY skill, he would like I setup the Ventus for him plug and play, without sending me back to setup again.

And one Bi-Polar Supply will serving one Ventus board (one channel), +/- 18V rail with 2 x 30VA 18VAC transformer (+/- 15V and +/-18V tested at my setup, +/- 18V perform better on AKG K-1000)

Questions:

Powering Options

Q1. Does the Ventus2 current requirement varying with the load impedance of difference headphones plugged in, also impedance changing with frequency? If I use Shunt Type like Placid BP, how to decide the amount of shunted current at idle without making too much heat, and not hurting performance when current requirement suddenly raise? From Placid Manual, seems +/- 15V recommended, so +/- 18V not recommended?

Or LCBPS is better option here?

Gain Setting

Q2. If an external switch on the panel will be install to set gain for low-high impedance headphone and Pre-amplifier Line driver, by switch R3 between 2 set of resistors, what's the value you will recommended for Low and High imp Headphone and Pre-Amplifier? If R5 remain as 2K.

Input impedance:

Q3: Input from normal consumer line level source of SACD player, CD Player, and DAC with single-ended connection, Tentlabs volume control module placed in front of the Ventus input, what's R4 value recommended, or leave it open?

From Tentlabs website Specification:
Input impedance: > 40 k-ohm (actual value depends on volume setting)
Output impedance: < 8 k-ohm (actual value depends on volume setting)

Grounding
Q4: Should the Chassis grounded to IEC inlet grounding lug?

LME49600

Q5: What's the BW mode of LME49600 in Ventus kit?


Thanks for the advise! and any ideas can further improve the current usage and setting would be much appreciated!!


Q1: Current demand does change with load impedance, yes. But this is not a problem even for Placid BP, just set the shunt current to the max anticipated current draw + 10-20% margin. Otherwise the LCBPS is a very good choice.

Q2: I really can't answer this as it really depends on the desired output swing you want. How much gain do you need? In any case I would be very careful doing this. Those feedback nets should be very short. Running a switch to a panel will likely compromise signal length.

Q3: That volume control has a very high output impedance. That is not going to be ideal for the Ventus, but it should still work fine.

Q4: Yes but only the chassis.

Q5: High BW.
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Hercules  
#3 Posted : Saturday, January 15, 2011 3:15:21 AM(UTC)
Hercules

Rank: Advanced Member

Groups: Member
Joined: 4/16/2009(UTC)
Posts: 56
Location: Hong Kong
Thanks Russ, order placed!
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Hercules  
#4 Posted : Friday, February 25, 2011 8:47:29 PM(UTC)
Hercules

Rank: Advanced Member

Groups: Member
Joined: 4/16/2009(UTC)
Posts: 56
Location: Hong Kong
Just complete everything today!

UserPostedImage

UserPostedImage
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Russ White  
#5 Posted : Friday, February 25, 2011 9:02:59 PM(UTC)
Russ White

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Joined: 10/24/2006(UTC)
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Location: Nashville, TN

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Wow nice work! How are you enjoying it?
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Hercules  
#6 Posted : Friday, February 25, 2011 10:24:34 PM(UTC)
Hercules

Rank: Advanced Member

Groups: Member
Joined: 4/16/2009(UTC)
Posts: 56
Location: Hong Kong
Well, the volume control module seem defective one, stepping after 33st step have pop noise. Now using gain of 4, just right for both headphone and pre-amplifier, no switching R3 resistor required I think,
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