Buf-03

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#21
carlmart said:
Walt Jung's latest version of his "diamond" discrete buffer can be seen here:

http://213.100.118.115:7000/HaloFiles/HIFI-AMPS/HiFi Discrete Buffer - Schematic.gif

I am trying to find this buffer article on the Web but it doesn't seem to be there.


Carlos
Click to expand...


Even if it doesn't look (at least to me) totally similar to the BUF634 (the 634 has 4 output transistors, and more diodes), the designs are interesting


BTW, on your schematic, what does the dotted lines represent?
I don't understand the roles of all of these diodes in this schematic and in the BUF634
 
#22
Christer:

The reason for RC = RS is to balance out source impedance/resistance seen by the two input (+ and -) of U1A, minimize DC offset wich is a product of the Input bias current into + and -.

Calmart:

I did think about it but, it have to be something with his grounding in the measurement system.

If you look closer it is there also when he just make a loop on his sound card (blue baseline)....
So it has nothing to do with the MINT module at all.

It adds nothing to this measurement! Very important... So the MINT is just fine
 
#23
sonnya said:
Christer:

The reason for RC = RS is to balance out source impedance/resistance seen by the two input (+ and -) of U1A, minimize DC offset wich is a product of the Input bias current into + and -.
Click to expand...

I understand that. My "problem" is that as far as I understand
RC = RS is an approximation to the optimum value, although a
reasonable one, given the values in the diagram for the other
resistors. Howver, since Jung seems to discuss the general
theoretical issue and supplies the diagram merely as an
example, I am not 100% sure whether he tacitly makes an
assumption that RC can be approximated as RS, or if that
actually is the theoretical optimum (in which case I have not
understood the theory).
 
#24
Bricolo said:

Even if it doesn't look (at least to me) totally similar to the BUF634 (the 634 has 4 output transistors, and more diodes), the designs are interesting

BTW, on your schematic, what does the dotted lines represent?
I don't understand the roles of all of these diodes in this schematic and in the BUF634
Click to expand...


You're right on the 634, but it does resemble it. The original buffer circuit was a "discrete LH0002".

It is not my schematic, but Jung's. The link was a reference to the first article, but I couldn't find the rest. The dotted lines were options probably, but I don't remember the rest of the parts role.

I think I did cut the articles from the mag, but I'm not sure. If I find them I let you know.

You can always ask Jung himself, if the mail address still works.


Carlos
 
#30
I am at my workplace now, so i have to post the result later.

But the Background noise is my problem. My sound card is the one build into my computer.

Via chip by the way.

There is a small level 50Hz..

The only thing i can see is that the AD8610AR adds nothing to the IMD test.

MY soundcard has a level of .004% in loop through.

But your card is very fine.... Which one do you use?

I have thought of buying the new AUDIGY2 PLATINIUM EX. Is has low noise level and SPDIF IN and OUT.
 
#33
PMA said:
Sonny,

I have imagined that AD8610AR adds nothing.
We had the biggest troubles with in-card generators. So we use external ones. It is all done by a colleague of mine, great job.
Click to expand...

It looks like it adds nothing. Under all circumstances it is masked by the soundcard.

Bricolo said:
PMA and Sonnya: what software do you use?
Click to expand...

I use DazyWeb software. It does a good job
 
#40
PMA,

Indeed, you are right. The 6171 and 6272 don't have quite the
same specs. So many people both here and at AA have claimed
6172 to be a double 6171. Since the specs are very similar and
I haven't compared the datasheets side by side, I have found
no reason not to believe that. Until now, that is.
 
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