Loudness stage

[anchorman]

That’s something entirely different to what I was talking about. But it is interesting!

 

[Brinkman]

See also this post in another thread

 

[jfetter]

I have found in junk store, Onkyo TX-82 with 'variable loudness' and will be auditioning for a while before transferring to a test ckt. Its called Selective Tone
and uses a two terminal pot.

 

[Brinkman]

This is a passive loudness circuit that can be put on the end of a pre amp...

The effect as you turn the pot over full rotation is...

The 33k resistor is just to simulate a typical load and is not needed it will drive a following circuit over about a 20-100k range withought very much change in the frequency response.

The component values can be scaled to for instance use the 10k motorised pot widely available here in Oz. In this case just double all resistors and halve capacitors.
rcw

I purchased a 24-position balanced stereo attenuator and I’m wondering if the above circuit would work with it (I will stuff it so that each deck is 5K nominal). I like the LF compensation but would prefer to omit the HF compensation. I am assuming omitting the 5.6k resistor and 2.2nF cap would accomplish this. See the attached for my desired boost. Any thoughts/advice are welcome.

 

[Brinkman]

The attachment above was accomplished with the following stepped attenuator circuit:

 

[Brinkman]

So I did the math for the above ladder network from 1949 and calculated that the attenuator is roughly a 12.7k ohm load at 1000Hz. Sorry for the poor picture quality, I am outside and it is 1:00AM locally.

 

[isbarbato]

I built the circuit from post #10 in a very handmade way, I liked it a lot, I just added an on and off button and made it separately for each channel, as I didn't have a potentiometer I used a trimpot.

 

[diyralf]

Unfortunately, the circuit @#10 is not a working loudness circuit. If you're happy with that, then it's okay. If the loudness is correct, the level is below -40dB at the 8 o'clock volume pot position. In this circuit it is almost 0dB. These are all auxiliary circuits that work terribly. The problem is you can't get tapped potentiometers anymore. Attached is a correct loudness curve according to the human ear. And by the way, the loudness circuits in 95% of all hi-fi equipment do not work correctly. Yamaha is still the best but not quite correct.

 

[tiefbassuebertr]

check out post #7 in this thread:
https://www.diyaudio.com/community/...ndependent-loudness-effect-what-rules.365053/
I want to know, how I convert a loudness function from a level dependent in a level independent version.