Reverse of the old Loudness Control

[Pano]

Yeah, but it sounds so good. Just something about a DC coupled amp.

OK, back on topic, sorry.

[pheonix358]

[Don Hills]

Ok,

I've been through my back issues of Silicon Chip.

The July 1996 issue has a 3-band parametric equaliser. It's a very basic circuit, all 3 bands are standard boost/cut variable Q (bandpass). It wouldn't be very suitable for loudness compensation, where we require a relatively shallow LF boost and then a sharper cut for excursion control.

But as I was putting the magazines back on the shelf, I glanced at the cover of the December 1997 issue. "Loudness control for car hi-fi." It appears to be intended to do almost exactly what I have in mind. I'll summarise the article later.

[pheonix358]

Originally Posted by Don Hills

Ok,

I've been through my back issues of Silicon Chip.

The July 1996 issue has a 3-band parametric equaliser. It's a very basic circuit, all 3 bands are standard boost/cut variable Q (bandpass). It wouldn't be very suitable for loudness compensation, where we require a relatively shallow LF boost and then a sharper cut for excursion control.

But as I was putting the magazines back on the shelf, I glanced at the cover of the December 1997 issue. "Loudness control for car hi-fi." It appears to be intended to do almost exactly what I have in mind. I'll summarise the article later.

Have a look , if my memory serves me well, at the 4th section. The parametric was three stage as you said, there was a fourth stage.

Terry

[Don Hills]

Originally Posted by pheonix358

Have a look , if my memory serves me well, at the 4th section. The parametric was three stage as you said, there was a fourth stage.

Terry

Nope, definitely just 3 bandpass stages. But like you, I'm sure I've seen a circuit for a parametric with a shelving filter at the LF end somewhere.

I'll take a look through the yearly indexes and see if there were any others.
According to the SC Web site, there was a subwoofer controller with parametric EQ in the December 1995 issue. It was updated in 2007:
Silicon Chip Online - Subwoofer Controller
Maybe that was it?

I've now looked at the loudness control from the December 1997 issue.
It's not suitable. The LF boost starts too far up the frequency range, and the amount of boost actually starts to reduce again as the volume setting nears minimum. It also boosts the treble as well as the bass, which I have always found unnatural. The response curves were apparently arrived at by experiment, which likely means the curves were chosen to suit a typical car stereo rather than a home environment.

[davygrvy]

Originally Posted by jamikl

I guess I am looking for a circuit to reduce boost with increasing volume but operated off the volume control so that two separate controls are not needed. This is to reduce xmax at high volumes. Thanks for any help, negative or positive.
jamikl

See Reading driver displacement with radar!

Why not monitor actual displacement and use that as a key to limit input signal to the LF driver? No preamp mods required.

[Artie]

Originally Posted by Don Hills

What is needed is a progressive bass boost/cut control linked to the volume control, along with a gain setting control that lets you calibrate your system to the standard.

Sorry to revive this old thread, but I found this while doing a search for "subsonic filters".

Isn't the above exactly what Yamaha was doing with their older recievers and amps from the 70's and 80's? They all had the variable loudness control that worked in conjunction with the volume control. One could simply download an old Yammy schematic and copy their loudness technique.

[Don Hills]

I'll take a look, thanks. I even have an old Yamaha receiver awaiting restoration, I'll check if it has the control. (It's so old it has tiny vacuum tubes (nuvistor 6CW4) in the RF stages of the FM tuner.)

[AJinFLA]

Originally Posted by Artie

Isn't the above exactly what Yamaha was doing with their older recievers and amps from the 70's and 80's? They all had the variable loudness control that worked in conjunction with the volume control.

I recall the Yamaha's with the variable loudness controls, but I don't think they were tied to the volume.
The Chase that I mentioned previously, did just that.



cheers,

AJ

[Key]

I tried this out last night and it seems to work. It works for increasing and decreasing and the first volume is for calibration.