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akione  
#1 Posted : Tuesday, May 6, 2008 2:58:29 AM(UTC)
akione

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Location: U.K.

Hi Russ & Brian,

I'm wondering about trying out a slightly different configuration of my pre-amp/dac.(see gallery)

At present the Ballsie is on the output of the DAC and is fed as one of the inputs to the Balanced Input Darwin.

I'm thinking that, if I put the load-balancing resistors directly on the output of the Dac, and replace the Ballsie

with an IVY, but placed AFTER the Darwin, then the IVY would provide:

a) A first stage buffer for the pre-amp effective for all inputs.

b) A single-ended to balanced conversion for the SE inputs.

c) A true SE 'Tape Out' capability for all inputs, instead of the 'Direct DAC out' which I have at present from Ballsie.

The balanced outputs are, of course, then fed through the balanced Joshua Tree and then the output IVY giving a Balanced Headphone

driver and multiple SE outputs (via output Darwin).

Can you see any problems with this configuration?

My concern is in the comparison of Ballsie to IVY, ie THS4131 vs 2 x LM4562 inst. amp. Which is better?

Is the Ballsie in the current system providing something (lower CMRR perhaps?) which I would lose?

Do you think I'll need to do anything different with the 'first stage' IVY, other than changes to input and feedback resistors?

Thanks,

Colin

akione  
#2 Posted : Wednesday, May 7, 2008 6:06:00 AM(UTC)
akione

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Posts: 33
Location: U.K.

Anybody home ? Whistle
akione  
#3 Posted : Saturday, May 10, 2008 3:23:28 AM(UTC)
akione

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Joined: 2/8/2008(UTC)
Posts: 33
Location: U.K.

If anyone is curious about this, I've now removed the Ballsie and have used 1% 100 Ohm resistors

as a temporary set-up for load-balancing the DACs. I'm using the IVY for the output stage, but

have upped the gain slightly by using 1.3k resistors for Rf.

IMO the sound is smoother than with Ballsie in, and the SE output when fed to an external

headphone amp seems a bit cleaner.

I still want to try it with the additional stage, but at this stage I prefer the IVY.
Russ White  
#4 Posted : Wednesday, May 14, 2008 5:50:07 PM(UTC)
Russ White

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Hi akione,

Very sorry I did not get a thread notification. Did not mean to leave you hanging.

As you may have noticed, the IVY is indeed a very good match for the opus. It sounds great. 100 ohms resistors are a good choice, though you could go lower. I would suggest 10-21R.

Glad you got it sorted out. :)

Cheers!
Russ

akione  
#5 Posted : Wednesday, May 14, 2008 10:49:13 PM(UTC)
akione

Rank: Advanced Member

Groups: Member
Joined: 2/8/2008(UTC)
Posts: 33
Location: U.K.

No Problems, Russ :)

Thanks for the reply.

I've actually changed them now for 47 Ohm, 0.1% and it sounds superb. I may try something lower, but I find

it hard to believe it could be improved. :)
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