Shunt or serie volume control

[nelsonvandal]

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

Lumba, I have plans for a power amp based on my experience from the folded cascode headphone amp. I'll be using JFET/bipolar CFP in the input stage and maybe cascodes as well. SK170/SK246 as CCS to the LTP. Not sure about the current mirror. I'm quite happy with the folded cascode topology, so I think I go for that. I think I'll hang on to the diamond buffer output stage but with double EF. I've tried diode biased EF, but I don't like it as much as the diamond buffer. Since I know the importance of how the speakers return currents are handled, I'd like either a BTL or fully balanced amp.

Very nice amp Lumba, I'll bet it sounds absolutely fantastic. What output stage do you favor? I have a hunch you've already told me but I'm sorry I've forgotten it.

 

[nelsonvandal]

Lumba, I've been reading some of your old posts. Your ideas about CFP bipolar/MOSFET output stage looks interesting. Could you please show an example of a low power amp with MOSFETs available from ELFA so I could do some experimenting.

And sorry to you others for this threadjacking.

 

[Lumba Ogir]

Nelson,

I'll be using JFET/bipolar CFP in the input stage and maybe cascodes as well.

JFETs should always be cascoded in common source mode.

SK170/SK246 as CCS to the LTP.

You will need at least 10mA.

Not sure about the current mirror.

Check out the effect of R14 in your headphone amp.

I'd like either a BTL or fully balanced amp.

No dirty ground as far as the eye can see.

Take your time to plan the topology in detail. We can discuss it later.

 

[maxpou]

Hi Guys,
nobody can help me?

 

[Lumba Ogir]

maxpou,
what was the question?

 

[maxpou]

Hi Lumba,
look at post 13 and 20. Thank you! Maxpou

 

[Lumba Ogir]

Maxpou,
maybe I`m not the right person to answer your question but I would be happy with the values provided by that program.

 

[hifimaker]

You could leverage the best of both worlds and go with a ladder attenuator.

-David

 

[maxpou]

Hi Dw8083,
the ladder and shunt attenuator it's not same thing? What's the difference? Thank you! Maxpou

 

[AndrewT]

max,
you have not told us what attenuation steps you NEED to allow your system to operate at the levels you normally require.
Post 14.

 

[maxpou]

Hi AndrewT,
i don't know what is -70db as level, but i want the logarithmic level with soft start. I don't know if 2db step is too high? somebody can teel me the best curve? Thank you! Maxpou

 

[AndrewT]

measure your signal voltages.

 

[maxpou]

resistor

Hi guys,
i want order my resistors for my step att. but i have a question. I think PRP for shunt but What's the best resistor in serie. Thank you! Maxpou