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Old 15th August 2010, 01:52 PM   #101
sureshm is offline sureshm  Australia
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Transformer newbie here. Transformer cores become magnetized when dc flows in a winding. Any idea how much DC is fine and at what levels the magnetization kicks in? Thanks
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Old 19th August 2010, 10:24 AM   #102
Tyimo is offline Tyimo  Hungary
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Default Buffalo and LL1517

Rosendorfer!
Could you please show me how did you connected the LL1517 to your circuit?

Tyimo
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Old 25th August 2010, 08:38 PM   #103
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Dear Tyimo

Sory for late answer but for some time I was not looking hire.
As for LL1517 conection diagram I did use serial primary and serial secondary connection exactly as per http://www.lundahl.se/pdfs/datash/1517.pdf datasheet. I did experiment with diferent resistor at trafo output and end up with about 1kOhm, but this could greatly depends on Your next stage. In any question Please ask.

Rosedndorfer
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Old 26th August 2010, 04:32 AM   #104
Tyimo is offline Tyimo  Hungary
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Hi Rosendorfer!
Thanks!
Some more question:
- Where did you connect the secondary's pin 9th? The shield's wire?
- Where do you have the volume pot in your system?
- what is your next stage input impedance?

greets:
Tyimo
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Old 26th August 2010, 10:18 PM   #105
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Hi Tyimo

So Some answers:

Pin no 9...no connection... I did listening tests with my headphones and my Power Amp and did not find any differences so I have left it with no connection.

Volume pot.....Who needs expensive pots when you have buffalo..and Volumite... OK I know that there are guys that do not like this solutions but I'm personally big fan of Buffalo+Volumite this combo solves so many problems and works so nice that right now I even do not look at my precious AlpsPots and even more expensive hand made attenuator made out of military grade resistors with silver solder ...

If I could recommend go with Volumite...this will save You lot of problems...

And then You can go directly from trafo to Your Power Amp..no Pre.../OK with Volumite Pre is in the dac.../.

And this starts to be bit tricky...
I hope some wise guys will tell something about this if I'm relay wrong ..but ....

At output of Buffalo and as mather of fact the same is at output of LL1517 as this is 1:1 trafo You will have plenty of power please see my post #44 and see my scope shots with different resistors at trafo primary....And with 1kOhm this is about 4vp-p at 0dB. You can go lower with resistors but somehow I did not like the results of this and below 300-200 Ohm I did find that "dynamics" get cut...but this is just me and other guys could thing/listen diferent... .

So we have got 4V p-p and...this is too much to connect to "regular/standard" power amp @usualy about 20 times amplification...
So actually there are two solutions ...or use Volumite or Pot "hard way" about -40to -60 dB but this is just waste of dynamics....and no good...
Or... cut Your PowerAmp amplification...
Thing about...
Your Dac+LL1517 with PowerAmp should be set up to work together in "optimum" configuration...Buffalo is giving You 4Vp-p Pure Music/Dynamics so do not waste this by 300W Power Amp ....with -80dB Pot..@.input.
What for 20x amplification when all you need is 2-5 times in "normall" listening situations...

So back to Your questions ..... next stage input impedance...

In my system it is about 10kOhm and my PowerAmp has amplification about 4x and then Volumite is set at 8 or 9..out of 10max..at usual listening level ..

OK and very nice Trafo feature is that You can remove Caps at Your Amp Input...No DC ....

Vell I hope that will answer some of Your questions...

If I could help please ask...

Rosendorfer
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Old 27th August 2010, 07:01 PM   #106
Tyimo is offline Tyimo  Hungary
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Hi Rosendorfer!
Thanks for the answer and help!
One more question:
What is the output impedance of your Dac? The LL1517 likes under 10 Ohm to be drive the primary.

Greets:
Tyimo
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Old 27th August 2010, 09:28 PM   #107
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Hi Tyimo

Well from Russ White informations that he shares on this forum, Buffalo output impedance is about 195 Ohm in stereo mode..if I understand him correctly.
If LL1517 likes this or not I did not ask, but I know that this is working realy nice...

Greets
Rosendorfer
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Old 27th August 2010, 11:14 PM   #108
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Hi Rosendorfer,

Thank you for sharing!

Did you remove the input caps at your amp? If so, how substantial is the sonic improvement?

I'm also using Lundahl transformers (LL1527) with my Buffalo, and I really like what I'm hearing

Cheers,
Alex
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Old 28th August 2010, 01:02 AM   #109
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195 ohms for each phase, so it's 390 ohms total .... higher than ideal for most transformers, not that it can't still sound good of course.

Quote:
Originally Posted by Rosendorfer View Post
Hi Tyimo

Well from Russ White informations that he shares on this forum, Buffalo output impedance is about 195 Ohm in stereo mode..if I understand him correctly.
If LL1517 likes this or not I did not ask, but I know that this is working realy nice...

Greets
Rosendorfer
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Old 28th August 2010, 05:09 AM   #110
Tyimo is offline Tyimo  Hungary
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Hi Rosendorfer!
Quote:
Well from Russ White informations that he shares on this forum, Buffalo output impedance is about 195 Ohm in stereo mode..if I understand him correctly.
If LL1517 likes this or not I did not ask, but I know that this is working realy nice...
Thanks for the info!!
May be your load resistance (1K) is optimal in this situation.

greets:
Tyimo
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