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Old 14th February 2011, 01:43 PM   #3661
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Quote:
Jim Leach posted:

2) If I understand correctly, I could run balanced OR single ended output. Could I possibly have two sets of connectors on the back of my unit to allow both? If so how?
Yes, See "Typical Application" on the first sheet of this:

http://www.jensen-transformers.com/datashts/11ympc.pdf

Note: You don't try to use both at the same time...
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Old 14th February 2011, 02:51 PM   #3662
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Old 14th February 2011, 02:55 PM   #3663
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Originally Posted by Ed LaFontaine View Post
Yes, See "Typical Application" on the first sheet of this:

http://www.jensen-transformers.com/datashts/11ympc.pdf

Note: You don't try to use both at the same time...
Hey Ed!

I cannot open that link (blocked by my blocker) do you know another way into that?

EDIT=> I got it! (now some reading...)

Second Edit => And I know I can't run both at the same time, but thanks!
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Last edited by Jim Leach; 14th February 2011 at 02:58 PM.
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Old 14th February 2011, 11:54 PM   #3664
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Originally Posted by Jim Leach View Post
OK. I am getting back to this project after a long hiatus.

I am up to date on the reading (my eyes hurt!) and had a couple questions.

1) the Lundhal LL1690s seem to be the favored transformers from several sources, some of whom have tried many flavors. What is the best place to get these babies today?

2) If I understand correctly, I could run balanced OR single ended output. Could I possibly have two sets of connectors on the back of my unit to allow both? If so how?

3) in the case of the transformers, there apparently needs to be filter caps and some resistors as well. I have seen several examples, and at least one person using it 'bare'. What is the current 'state of the art' with regards to the components to be used in conjunction with the transformers?

4) I read something regarding the use of caps rather than transformers for output (but transformers seem to be favored). Are there any advantages to this scheme over the transformers?

5) I am reasonably certain the coax input will be relocated to the rear of the unit (remote of the board). I believe I therefore need a 'proper' RCA connector- i.e. not just a plain old audio one right? What exactly do I need, and where is a good place to get it? (or will an audio one work fine?)
There really is no proper RCA for digital, they are the wrong impedance, but the manufacturers use them any way. You can switch to BNC or even F connectors if you like, or just use RCAs.

The Lundahl 1690 and the Jensen JT11-DMs or BMs seem to be the top choices, but the Jensens are way cheaper over here.
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Old 15th February 2011, 06:16 AM   #3665
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hi guys

i am learning bout LOT. as 600:600 is used in this application. i am wondering what happen if 1k:1k is used? whats the effect to the sound in particular?

thanks in adv

erwin
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Old 15th February 2011, 12:59 PM   #3666
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The impedance rating has no direct bearing on the sound, the quality of the design and construction has everything to do with it.

Please go to the Jensen website and read the article by Bill Whitlock about audio transformers. Your questions will be answered.

Best, Bill
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Old 15th February 2011, 01:05 PM   #3667
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Originally Posted by milen007 View Post
hi guys

i am learning bout LOT. as 600:600 is used in this application. i am wondering what happen if 1k:1k is used? whats the effect to the sound in particular?

thanks in adv

erwin
Bill is correct about the Jensen article, it is quite useful.

One thing that will probably differ between the two transformers is the inductance in the windings. The consequence is that that depending on the load input impedance (somewhat) and the source output impedance (strongly), you will be creating a high pass filter and reducing the low freq response. Most manufacturers do not list the inductance, so you may need to experiment.
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Old 15th February 2011, 01:24 PM   #3668
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Originally Posted by Bill Fuss View Post
There really is no proper RCA for digital, they are the wrong impedance, but the manufacturers use them any way. You can switch to BNC or even F connectors if you like, or just use RCAs.

The Lundahl 1690 and the Jensen JT11-DMs or BMs seem to be the top choices, but the Jensens are way cheaper over here.
Thanks for that info Bill. Since I am integrating with 'commercial' transport and preamp before and after, respectively, I want this to be 'robust' and able to handle future changes before and after if they occur. Obviously tailoring everything in the chain is best; however I have to be practical for myself as well.

I have no doubt this gizmo will sound so much better than my Aragon D2A (version 1!) so I will be happy!

PS a member here has provided me with some Lundahls so I'm going for them! Just a few details to sort out and I'll be sniffing solder fumes!
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Old 17th February 2011, 06:17 PM   #3669
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Hi All. I recently received a completed DAC that is based on this diy project. It came with the dual LME49720HA op-amp installed and with 2 others in reserve : a dual LT1363 and a dual OPA627. I presume the effect of exchanging one op-amp for another would be tonality changes. Can someone point me to a page or link where I could learn of these differences in tone?

Thanks very much.
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Old 17th February 2011, 06:40 PM   #3670
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Originally Posted by msjjr View Post
Hi All. I recently received a completed DAC that is based on this diy project. It came with the dual LME49720HA op-amp installed and with 2 others in reserve : a dual LT1363 and a dual OPA627. I presume the effect of exchanging one op-amp for another would be tonality changes. Can someone point me to a page or link where I could learn of these differences in tone?

Thanks very much.
To be honest the whole op-amp thing is subjective and opinions will vary as much due to equipment and set up as well as musical tastes.

I preferred LME49720HA to OPA627 but don't ask me to use subjective hi-fi speak - it just made the music sound better.

You could do a search on the forums for the op-amp models in question but really you should plug them in and have a listen. It's the only way to find out
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