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Old 15th September 2011, 05:33 PM   #201
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With the quality and price of the Feastrex transformers, a top notch quality resistor is in my oppinion mandatory. You might want to try these resistors:

* TX2575 bulk metal foil type
* Caddock Mk132
* Caddock USF TF020/USF340
* Tantalum by Shinkoh
* PRP PR9372


/S.

Quote:
Originally Posted by wktk_smile View Post
Hi, staccatiss,

I had simply inserted load resistor in secondary as their recommendation.
I used 2.4k ohm generic metal film I just found in my junkbox.

I felt "brightness" in treble decreased with Finemet transformer in comparison to previously used I/V stage. That's not always, but with some recordings.


Later I realized this kind of brighter treble of previously used discrete op amp I/V tend to have fogginess - this actually masked details in some extent - at the same time.

Here's related article in Mr. Yukihito's blog. (in Japanese only)

Feastrex????????????????? | SD????????????????

Cheers,
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Old 19th September 2011, 01:03 PM   #202
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Default I must correct impressions in my previous post

I have recently noticed that my BII hadn't work properly at least during borrowing the Finemet transformers.
Somehow one of the 8 outputs in the dac failing to output (+) correctly.

After receiving the transformers that I had ordered, I had re-checked the dac and made sure working properly.
Now BII with Finemet transformer sing much better.

I have to correct my previous impression of them, especially about treble and soundstaging.
High frequencies now have enough sparkle and more airly presentation.


Cheers!
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Old 23rd September 2011, 07:39 PM   #203
Ciu is offline Ciu  France
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Quote:
Originally Posted by Joe Rasmussen View Post

NOW TRY THIS:

Click the image to open in full size. C:

What you might call this, I don't know. It is not current I/V in the regular sense. But do note that we now have traded some of the offset voltage for current offset. Again the maths is simple, same as above:

1.65V/(195+330R) = 3.1mA

The offset voltage will be just above 1V DC. That DC will not go through the transformer, only AC current will be seen by the Primary. Looking AC wise, it also looks like a voltage divider:

(330R(195R+330R))*2.1VRMS = 1.3VRMS

But there is also another way of looking at it: The 3.1mA DC current offset is at least less that a tenth of the peak AC current required on the Secondary of the 1:1 transformer in pretty much all circumstances. The Sabre DAC is essentially modulating that current. Think of it as an iddle current being modulated.

Some kind of current processing is going on, but not in the sense of a proper I/V converter - which I still believe to be ideal, but maybe we are not looking for the ideal, just a better compromise for transformer use.

Bottom line, IF only 1.3V RMS output does not ruffle your feathers (it does some, but shouldn't), then like any good soup, how does it taste? [B][COLOR="Red"]

Cheers, Joe R.
Hello Joe !

I've tested this one ....Excellent !!!
I had on my shelves, an very good Jensen JT11-EMCF, a 600:600, 80% nickel core, 40 Ohms DCR Pri/sec
I've spent my afternoon to play music (about 60 p.) , listening with a special care my "reference playlist"
This simple combination gives a very good resolution with details, opened-air music ...

Thanks to Joe, for this excellent suggestion !!!

Richard
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Old 24th September 2011, 07:34 AM   #204
loreliv is offline loreliv  Italy
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Quote:
Originally Posted by Ciu View Post
Hello Joe !

I've tested this one ....Excellent !!!
I had on my shelves, an very good Jensen JT11-EMCF, a 600:600, 80% nickel core, 40 Ohms DCR Pri/sec
I've spent my afternoon to play music (about 60 p.) , listening with a special care my "reference playlist"
This simple combination gives a very good resolution with details, opened-air music ...

Thanks to Joe, for this excellent suggestion !!!

Richard
Hello Richard
I think, I read that you were using the jt-11p-1, these jt11-EMCF sound better with the buffalo II ?
thanks for the reply, greetings Loredana
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Old 24th September 2011, 09:49 AM   #205
Ciu is offline Ciu  France
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Quote:
Originally Posted by loreliv View Post
Hello Richard
I think, I read that you were using the jt-11p-1, these jt11-EMCF sound better with the buffalo II ?
thanks for the reply, greetings Loredana
Yes, I was using JT-11-P1, that was during several months...after a quick start with TPA first output stage bought with Buff-9008


Then ,until now, I tried an Edcor, wired ~7x, with 1800 Ohms on secondary, followed by a tube buffer...

If I compare JT11p1 with JT11-emcf, the sound was more "concentred" to mids and hights, with a bit of "metallic" in upper frequencies

The main difference now, is in "natural sound" , and an "opened air", with strong low freq.

I think to test in some weeks, "current mode" with 3 ohms and tube output stage ~40-50x gain

Richard
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Old 26th September 2011, 03:08 AM   #206
fulken is offline fulken  United States
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Default Premum Finemet Transformers

(I do not want to hijacking this thread)
I just prepared thread for Finemet DAC transformer for ES9018. You can find detail for getting your evaluation unit and process.

Please try this link below.
Premium Finemet Transformers
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Old 16th October 2011, 09:07 PM   #207
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Quote:
Originally Posted by Ciu View Post
Hello Joe !

Thanks to Joe, for this excellent suggestion !!!

Richard
I too switched over from loading my LL1684's with ~2K to running the 3.1mA offset, and I am very happy with the results! Thanks!
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Old 17th October 2011, 02:21 AM   #208
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I have a pair of BIIs running in dual mono mode. The outputs are fed directly into a pair of Joe's quadfillar wound transformers (195ohm impedance). When Joe first shared his resistor loading trick with me, I tried 150ohms, then 75ohms and now 47.5ohms. The results were truly pleasing. I am now tempted to go even lower as I have more than enough gain in my line-amp.
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Old 21st October 2011, 01:06 AM   #209
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Anyone compared Lundahl transformers with legatto?
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Old 22nd October 2011, 02:05 AM   #210
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Quote:
Originally Posted by Ciu View Post
Hello Joe !

I've tested this one ....Excellent !!!
I had on my shelves, an very good Jensen JT11-EMCF, a 600:600, 80% nickel core, 40 Ohms DCR Pri/sec
I've spent my afternoon to play music (about 60 p.) , listening with a special care my "reference playlist"
This simple combination gives a very good resolution with details, opened-air music ...

Thanks to Joe, for this excellent suggestion !!!

Richard
I still think somebody should try this with a Sabre DAC using Tubes.

Click the image to open in full size.

Normally Tubes are only good for voltage DACs, but use a transformer like this and you will have a Tube I/V stage - and it is the Sabre DAC that makes it possible - offset current = 8mA (I wouldn't do this with any other DAC I could think of). It can be pulled all the way to ground on the Primary and the Secondary grounded - and just input to the grid of your favourite Tube - and away you go.

Somebody should try it - requires gain about 50.

Cheers, Joe R.
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Last edited by Joe Rasmussen; 22nd October 2011 at 02:07 AM.
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