B1 Buffer Preamp

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#682
there is no need for complicating ...
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I would hardly call two resistive dividers a complication unless you are ultra-orthodox; the question is really does the proposed method bring any advantage, such as cancelling out common mode signals, or does it not work. If you are going balanced you might as well try the best alternative.
 
#684
Zen Mod said:
there is no need for complicating ;

one stereo B1 per channel , and that is balanced B1

if simplicity is goal , one can't make it much different
Click to expand...


Is it really this simple? So each half of the balanced signal could go through this buffer, without say a negative rail voltage needed for the side the negative signal goes through?

If I just have to make two of these, that is easy.
 
#685
I would like to use the DS1802 digital pot in front of the B1 (or B3:clown: ). NP uses the DS1802 in INT-150 and XP-10.

The main issues. More than 5V Vcc drives the pot into clipping. Proposal of Maxim: A wheatstone bridge!

The following stage should have a high impedance cause the DS1802 has 45kOhm impedance.

So, what solutions would be best to fit these two issues? How can I increase the input impedance of B1?

Perhaps NP could lift a little secret?😉
 
#687
New subject maybe:

Hello All

Can someone tell me what a typical measured vgs is, when you do the test on LSK170's type "B" N FETs as outlined in Nelson Pass's article on matching?
These devices are headed for duty in the B1 buffer.

Ive measured about 20 of these devices now and I'm getting anywhere between .220V and .240V.

Does this sound correct?

I just want to make sure Im doing the test correctly by seeing if the results sound right.

I set up a little test setup based on Nelson Pass's device matching article and think I've followed it exactly as laid out in the article.

I used a 15 volt regulated supply, and a 2.2 K source resistor. The only way that I changed the procedure was to put a DC ammeter in series with the power supply.
I get a measured 6.67mA with just about every device.

So, is this in the ballpark? Thanks for the help.

Curt
 
#689
I used a 15 volt regulated supply, and a 2.2 K source resistor.... I get a measured 6.67mA with just about every device.
Click to expand...

Small wonder, a 2,2K source resistor will, at 6,67 mA, have 2200 * 0,00667 = 14,674 Volts across it, that allows the JFet barely to turn on and sets the limit for the current you can measure. First, a 100 Ohm resistor would be more appropriate for this JFET, at, say 10 Volts. Secondly, some basic reading on electronics would be in order, you should at least be able to calculate voltage/current/resistance.
 
#690
Zen Mod said:



hardly 😉

input imp. of B1 AFTER the pot is well near 1M , so you really don't need to increase it
Click to expand...

so for an inpedance variing relay attenuator like Joshua (realatively low 2k to 3k typical) it would be most suitable to place it after B1? As long as the ground(s) of the different inputs is shared, it won´t produce earthquake Plops when "hot pluggin´" rca- connects, i guess.
 
#693
Zen Mod said:



considering what ?

you mean - using B1 as buffer between source and (heavy loading ) Joshua ?
Click to expand...

Yes. JT has approx 750 Ohms output imp. I would use it like source to little box with input select (i ´d have to dtudy how to manage the "divided input signal"), Joshua and than B1. This would be a quiet universal Buffer. And maybe for additional gain (for F5 for example) one could even put some tubegain after it?

or…isit nonsense
:apathic:
stefan
P.S: I´m running the B1 with cheap 1€ 50kpot at the moment and maybe my phono pre would not have a problem to drive even Joshuas imp. But just to be shure and sleep tight, i would prefer a higher input imp (and not throwing joshi away)
 
#695
I know I will never get a job at Pass Labs...

but here is my humble effort with the B1 Buffer...
or, while you argue I construct...


http://picasaweb.google.com/maxlorenz24/PassB1Buffer#5251640095436181634
There are 5 picks on the album. You can use the magnifying lens option.
Yes, the box is obtained from a computer-s SMPS.
Any advice is welcome 😀

This is the plain B1, safe that I use a voltage regulator, the TeddyReg, which can be hardly seen on the picks.

Million thanks to Mr Pass for his altruism and sorry to be so late...I am building some amps to match with it 😀 especially the also single ended ZCA or zero component amp...😎
Zenmod, you will see what monster speakers I will build next! :clown:
They will need only a few watts and this transparent pre.

Cheers,
M
 
#698
Music!!!

Woe, boys!

There is a saying on Hungary at us here:

The child gets lost between many midwives:

THE MUSIC

http://www.diyaudio.com/forums/showthread.php?postid=1618657#post1618657

From this direction nobody has an opinion?
This is not too important for you?
More important thing to trample into somebody else soul on the reason of this, possibly?
I ask everybody this!
Because this is the deafs dialogue really then, already again once.

Let there be peace with us.

Gyuri
 
#699
This is from Dr. Pálhegyi Ferenc, a Hungarian psychologist:

"The communication has two elements: reception and transmission.

The reception of the message.

It may be one of its reason if the other man's message does not get to me, that I cannot catch his broadcast, there is a mistake so is in my customer apparatus.

The deaf brother-in-law's anecdote exemplifies this:

– Good day, brother-in-law!
– I patch a boat.
– Back what your old man does?
– His bottom wore out.

(The text of Zoltán Kodály choral work)


The reception of the transmission at many times, not bodily, but spiritual deafness, which is the egocentric one because of an attitude, causes it to arises.
That is not the fail of communication in technique, but the man fails."

I ask indulgence because of my stunted knowledges of English only again now. But according to me understands the message that I tried to interpret if somebody wants it.

Gyuri

PS.
We do not draw a distinction between his and its in the Hungarian language. So in the lyrics his equal its.
 
#700
Gyuri said:
This is from Dr. Pálhegyi Ferenc, a Hungarian psychologist: ...........

Gyuri
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Gyuri .......... gimme a break ........ I live with one psychologist :clown:

I found that your posts are goodwilling and amusing , but I have suspicion that you're using some sort of Hu-English translator ........

so - sometimes is deciphering your posts even harder than understanding mine ..... :clown:
anyway - you can write whatever you wish , just because you already does your homework with basics .
 
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