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Old 23rd June 2012, 02:59 AM   #3381
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Choky

I looked at the data sheet and believe on the input side the two primary windings should be hooked up in parallel. ( 2 and 4 connected ; 1 and 5 connected.) positive phase connected to 2/4 and negative phase to 1/5.

Alternately 1 and 4 could be grounded and positive connected to 2 and negative to 5.


On the secondary side the center taps (6,9) should be grounded as you mention in previous post and plus output connected to 7 and negative phase to 10.

With a gain of 4x the 2V RMS from DAC should be raised to 8V

Thanks
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Old 23rd June 2012, 03:18 AM   #3382
Zen Mod is offline Zen Mod  Serbia
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what sort of signal you are using ?

ballanced ,symmetric , non-ballanced ?

if you use primaries connected in series , with CT grounded at signal side , and secondaries in series - with their CT connected to gnd at receiving side .......... you'll have both perfect symmetric balanced ........ and gain of 2:8

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Old 23rd June 2012, 03:18 AM   #3383
regal is offline regal  United States
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Quote:
Originally Posted by flocchini View Post
Choky

I looked at the data sheet and believe on the input side the two primary windings should be hooked up in parallel. ( 2 and 4 connected ; 1 and 5 connected.) positive phase connected to 2/4 and negative phase to 1/5.

Alternately 1 and 4 could be grounded and positive connected to 2 and negative to 5.


On the secondary side the center taps (6,9) should be grounded as you mention in previous post and plus output connected to 7 and negative phase to 10.

With a gain of 4x the 2V RMS from DAC should be raised to 8V

Thanks
That looks ideal for the Hifimans, only gotcha would be the transformer distortion at low frequencies (which are usually worse the larger the winding ration ie gain). Would be nice to find a simple low distortion 2-4x jfet gain/buffer design to compare.
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Old 23rd June 2012, 03:32 AM   #3384
Zen Mod is offline Zen Mod  Serbia
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well , sometimes is nice to use xformer to get rid of absolute DC offset , as is case with diff. DAC chip output

several times I found that solution better than Jfet buffers with caps in signal route

whatever - there is supplement pic to my previos post
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Old 23rd June 2012, 03:36 AM   #3385
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Thanks regal and Zen Mod

My input signal is balanced.

May be time to experiment
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Old 23rd June 2012, 03:42 AM   #3386
Zen Mod is offline Zen Mod  Serbia
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off course that you can skip connecting primary CT to signal gnd side

as I'm saying frequently - gnd is just state of mind

few tips :

-depending of signal source impedance , freq. sweep will show does secondaries need some loading or not

- it's worth trying xformer as in M1 - nested between input buffer and output stage

- it's worth trying xformer connected as autoformer ; if you need drawing of that ,just say .
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Last edited by Zen Mod; 23rd June 2012 at 03:49 AM.
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Old 23rd June 2012, 02:45 PM   #3387
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Quote:
Originally Posted by Zen Mod View Post
off course that you can skip connecting primary CT to signal gnd side

as I'm saying frequently - gnd is just state of mind

few tips :

-depending of signal source impedance , freq. sweep will show does secondaries need some loading or not

- it's worth trying xformer as in M1 - nested between input buffer and output stage

- it's worth trying xformer connected as autoformer ; if you need drawing of that ,just say .
I would need drawing
Thanks
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Old 23rd June 2012, 03:01 PM   #3388
Zen Mod is offline Zen Mod  Serbia
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when you choose exact xformer for first test , just say
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Old 23rd June 2012, 04:07 PM   #3389
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will do
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Old 24th June 2012, 10:34 PM   #3390
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Choky as you said

"- it's worth trying xformer as in M1 - nested between input buffer and output stage

- it's worth trying xformer connected as autoformer ; if you need drawing of that ,just say ."

With your schematic as reference would it be possible to connect transformer between junction of R4/R3 and junction of C1/C2.

I would use Jack Ellianos PVA2-N as generg favored it in post 23 of MAGMA thread - Introducing the MAGMA front end for BA-2 and F4

I believe it could also be wired as an autoformer. Cost is nice as 4 of these would be less than the Lundahls

Thanks

Bob
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