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Old 23rd April 2010, 06:47 PM   #41
glt is offline glt  United States
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Quote:
Originally Posted by Rosendorfer View Post
Just to put my 2 cents and sign to the club of BuffaloII & Transformers.

P.S.
If I could suggested to TP the only “right way” of mounting the AVC Shunt reg is of cause GLT way .
This should be in Buffalo manual, specially when except of listening to Your DAC You intent to make an photo of it .

All the best

Rosendorfer
Hi Rosendorfer, thanks for the support :-) but that's just me because I also like taking pictures of the projects.

Some questions on the transformers: are you using them as Balanced to SE converters? Regarding the impedance of the transformer, does the DAC sees the 9.2 ohm static resistance (meaning very little voltage swing) or the >1K impedance (meaning much larger voltage swing).

Seeing so much interest with transformers, perhaps TPA can do some testing and custom build/order transformers just like Crystek custom builds the clocks for TPA
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Last edited by glt; 23rd April 2010 at 06:49 PM.
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Old 23rd April 2010, 10:17 PM   #42
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Mount AVCC on top or bottom. Technically neither is more right than the other. It is just a matter of which position is most practical for you.

When using IVY-III or Legato, mounting AVCC on the bottom will not be very practical.

When using transformers choose which ever you prefer.

Cheers!
Russ
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Old 25th April 2010, 12:22 AM   #43
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Default Supporting GLT way of AVCC mounting as the “right one”

Dear Russ

Supporting GLT way of AVCC mounting as the “right one” was just my humble suggestion.

It accidentally happen to fit perfectly “practical” with IVY as You can see and I keep my fingers crossed it will be OK with Legato as definitely I'm looking forward to it.

As for technical reasons one could say that Sabre IC is getting just bit worm and having more "open air" does not hurts.

And You have to agree that this way Buffalo looks much better.

This is just innocent OT and excuse for me so I could post some more pictures. and I hope You will not take it very serious.

All the best.
Attached Images
File Type: jpg AVCC_By_GLT.jpg (87.1 KB, 1461 views)
File Type: jpg Buff_IVY_GLT_AVCC_01.jpg (70.6 KB, 1434 views)
File Type: jpg Buff_IVY_GLT_AVCC_02.jpg (79.8 KB, 1420 views)
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Old 25th April 2010, 01:46 AM   #44
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Default Buffalo and LL1517

Dear GLT

Supporting You is my "privilege".

But getting back to Buffalo and LL1517 or any other transformers. It seems that I have to "support" You again as definitely it would be very nice if somebody more knowledgeable with this subject could share some light on this. As Russ is explaining Sabre works as current output DAC only when DAC sees IMPEDANCE close to zero. And this with any type of transformers is probably not possible and 10 Ohm of LL1517 RDC is not relevant in this case.
I'm not trafo expert it is my first experience with them so I will not be making any theory what is better or "right".
I did made some measurements of my Buffalo connected directly to LL1517 in 1:1 /serial primary- serial secondary/ working with different load resistor at trafo secondary.

On first picture:
CH1 working with 1kohm load and CH2 with 2 kohm load.
On second picture:
CH1 is working with 100 Ohm and CH2 with 200 Ohm Load.

As some additional test for me quite surprising what this Lundahl's are capable there is 90 Khz (!!!) sine ruining through them with 1Kohm load.

As You can see Buffalo is giving really lot of voltage or power for any needs.
From My experience Buffalo and LL1517 works extremely well even as Head Amp for HD650 (300 Ohm) plenty of power with amazing bas. And also with HD550 (60 Ohm) (!!!).

If there is any test You or any of the guys is interested please let me know I will try to do what I can with my setup.

All the best
Attached Images
File Type: jpg 1k_2k_ohm.jpg (76.5 KB, 1393 views)
File Type: jpg 100_200_ohm.jpg (94.2 KB, 1323 views)
File Type: jpg 90_kHz.jpg (68.0 KB, 303 views)
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Old 25th April 2010, 02:24 AM   #45
avian is offline avian  Australia
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Thats absolutely amazing. Out of interest would you predict similar results using an LL1690 or one of the amorphous cored options from lundahl?

Quote:
Originally Posted by Rosendorfer View Post
Dear GLT

Supporting You is my "privilege".

But getting back to Buffalo and LL1517 or any other transformers. It seems that I have to "support" You again as definitely it would be very nice if somebody more knowledgeable with this subject could share some light on this. As Russ is explaining Sabre works as current output DAC only when DAC sees IMPEDANCE close to zero. And this with any type of transformers is probably not possible and 10 Ohm of LL1517 RDC is not relevant in this case.
I'm not trafo expert it is my first experience with them so I will not be making any theory what is better or "right".
I did made some measurements of my Buffalo connected directly to LL1517 in 1:1 /serial primary- serial secondary/ working with different load resistor at trafo secondary.

On first picture:
CH1 working with 1kohm load and CH2 with 2 kohm load.
On second picture:
CH1 is working with 100 Ohm and CH2 with 200 Ohm Load.

As some additional test for me quite surprising what this Lundahl's are capable there is 90 Khz (!!!) sine ruining through them with 1Kohm load.

As You can see Buffalo is giving really lot of voltage or power for any needs.
From My experience Buffalo and LL1517 works extremely well even as Head Amp for HD650 (300 Ohm) plenty of power with amazing bas. And also with HD550 (60 Ohm) (!!!).

If there is any test You or any of the guys is interested please let me know I will try to do what I can with my setup.

All the best
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Old 25th April 2010, 03:02 AM   #46
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Indeed AVCC does seem to fit quite well on the bottom side even when used with the IVY-III.

I am certainly going to second the idea that it will will work quite well when mounted as you have done(that is directly so that the profile is short).

There is also something to be said for direct soldering. It is the best possible connection.

Cheers!
Russ
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Old 25th April 2010, 12:21 PM   #47
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Avian

As for LL1690 I can only speculate that it will be working just fine. Sabre can hapily work with Curent Output and with Voltage Output so it seems that almoust any trafo will be working. But if it is "the right" trafo that will give You the best possible resoults with Buffalo I have got no idea.
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Old 26th April 2010, 03:56 AM   #48
glt is offline glt  United States
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Rosendorfer,

Thanks for the info. I have to admit that I had my doubt about fitting both IVY and AVCC in the bottom. I mainly wanted to solder the AVCC and still see the Sabre chip :-). Regarding the photos for the trafo, thus it seems the resistance in the secondaries is reflected on the primaries... (corresponding to the winding ratio).
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Old 26th April 2010, 06:01 PM   #49
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I did measure trafo secondary with different loads. If You find this interesting to test I can try to measure trafo input and output.
What I'm looking for, right now is the question how to find the "optimal" load resistance. Maybe 195-200 Ohm , if I understand Russ correctly, this is output impedance of Buffalo, so maybe “impedance matching” would be the “optimal”, or should I go the way of pushing Sabre more into Curent Output by lowering the load resistance gaining in theory less distortion, but then I'm afraid dynamics could be badly hurt. Any advise on this anyone.?
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Old 27th April 2010, 08:30 AM   #50
Marek is offline Marek  Poland
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I think with 1:1 trafo you should use Buffalo in voltage mode (high load on secondaries) because in current mode you have to make DAC to see extremely low impedance and with 1:1 trafo it is possible with extremely secondary load and extremely low output amplitude.....

I think you should connect trafo to Buffalo and do not use any output resistor - connect directly to your amp.

Voltage mode is theoretically worse in specs than current mode but diffirence is totally unaudible because ultra low THD isn't discriminant of sound quality. -108 vs -120 really doesn't metter.
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