Shunt or serie volume control

[maxpou]

Hi Guys,
I would like to know if i change my volume control ( Black beauty ) by stepped attenuator Elma, will I improve a lot my sound quality? And if yes what's the best shunt or serie. it's my preamp at this link post 32:
http://www.diyaudio.com/forums/showthread.php?postid=1541169#post1541169

Thank you in advance! Maxpou

 

[Zen Mod]

stepped is always better than plain pot

you'll hear difference as much your next stage is good ;

real shunt is always better than plain series

 

[tritosine]

alps black beauty is a stereo rotary switch with laser trimmed resistors, unless its a fake (there are plenty counterfeits) .

 

[maxpou]

Thank you guys for reply,
but the shunt stepped attenuator change my input impedance and change the sound too depending Charles Hansen, but if i read the borbely document he said there was no difference. Somebody can tell me who said true? Thank you! Maxpou

 

[maxpou]

Nobody can help me?

 

[Lumba Ogir]

maxpou,
is this your best shot for a good sounding circuit? I would in the first place make topological changes to get significant improvement.

 

[maxpou]

maxpou,
is this your best shot for a good sounding circuit? I would in the first place make topological changes to get significant improvement.

Hi,
thank you for reply Lumba Ogir, what do you want to change for improvement? thank you Maxpou

 

[AndrewT]

investigate the much simpler Pedja or Pass B1 buffers.

 

[lineup]

maxpou, this is my guess:

> You should change it, so it will be like one of Lumba Ogir JFET amplifiers
... the only drawback, is that it will no longer be your design
Lumba Ogir JFET amp circuits & projects topics,
which we have seen plenty many of (do I need to provide links?)
are those that can work very well and so not get critical comment from Lumba.
In fact, they are above John Curl class, if I have understood Lumba's posts correctly.


Personally, I like your amplifier very much.
You have done most everything possible to improve JFET Stages.
Using cascodes.
Maybe you have mentioned what Supply voltage you use?
It is not in schematic
http://www.diyaudio.com/forums/attachment.php?s=&postid=1541169&stamp=1213720316

My guess is like +- 18-20 Volt, regulated.

 

[Lumba Ogir]

maxpou,
are you sure you need any voltage gain?

 

[maxpou]

Hi guys!
thank you for fast reply!
I use 23V supply voltage look at: http://www.diyaudio.com/forums/showthread.php?postid=1524207#post1524207

I'm not sure if i need a voltage gain stage, i change the DAC in CD player and i think that i have 1,4Vp-p output.

thank you! Maxpou

 

[Lumba Ogir]

maxpou,
I`d go for a simple stage in keeping with this one.

 

[maxpou]

Hi guys,
i found this website for calculate the resistors for my shunt attenuator, but what's the best serie value and how many DB between each step because i have 24 step. Thank you! Maxpou

http://homepages.tcp.co.uk/~nroberts/shunt.html

 

[AndrewT]

Hi Max,
do you know what range of attenuation values you currently use?
Design each step to suit your needs.

It could be done with equal steps of 1dB giving a total attenuation -23dB.
or
steps of 1.5dB giving -34.5dB
or
steps of 2dB giving -46dB.
or
unequal steps.
Use big steps in the range you rarely or never use and small steps in the range you typically use. eg, 0, -6, -12, -18, -20, -22, -24, -26, -29, -30, -31, -32, -33, -34, -35, -36, -37, -40, -43, -46, -50,
-55, -60, -70.

You choose what best suits your use and your system.

 

[nelsonvandal]

maxpou,
I`d go for a simple stage in keeping with this one.

Lumba, I'm happy to see you recommending JFET/bibolar CFP, the best input stage. Just make it differential, and everything's honky dory.

 

[Lumba Ogir]

Nelson,
I have been doing that for years. Now, how far are you prepared to go?

 

[AndrewT]

r14=0r0?
only 2.5V cascode voltage on the CFP?

 

[AndrewT]

Hi guys,
i found this website for calculate the resistors for my shunt attenuator, but what's the best serie value and how many DB between each step because i have 24 step. Thank you! Maxpou

http://homepages.tcp.co.uk/~nroberts/shunt.html

that calculator does not make it easy to have constant Zin, nor does it take account of the Zin of the next stage.
Find a better calculator.

 

[Lumba Ogir]

Andrew,
R14 sets the (lowest) gain needed.

only 2.5V cascode voltage on the CFP?

Right, it`s not much of a cascode voltage.

 

[maxpou]

Thank you AndrewT,
i have elma shunt step attenuator and i never used step attenuator before, somebody can tell me your value resistors please. Thank you! Maxpou