I always liked the loudness feature on my Scott 222, was less “in your face” compared to the transistor stuff that had a similar thing. But maybe that was just that it didn’t have any wattage too.
I built this simple passive circuit and it works quite well to help poor sounding recordings with that annoying upper mid-range glare.
https://www.rfcafe.com/references/e...s-control-electronics-world-december-1963.htm
https://www.rfcafe.com/references/e...s-control-electronics-world-december-1963.htm
Yamaha variable loudness has been mentioned earlier in the thread - here is what it does on A-700:
positions 1...5:
positions 6...10:
Personally I consider it a good option to have available provided that the listener is not in the "direct only, no tone controls" camp.
positions 1...5:
positions 6...10:
Personally I consider it a good option to have available provided that the listener is not in the "direct only, no tone controls" camp.
Interesting posts. Loudness control was pushed on the basis of listening at night without disturbing others. The curves indicate that this isn't what they were actually achieving. A style of compressor would be more suitable. I have wondered if a modification to Dolby's 1st patent might be a good way of heading in that direction. Just the part used before music is recorded on tape.
Yamaha curves. I have been considering one of their dsp based units that offers loudness control. If it does what is shown it wouldn't do what I want. On the other hand it also offers "decompression".
Yamaha curves. I have been considering one of their dsp based units that offers loudness control. If it does what is shown it wouldn't do what I want. On the other hand it also offers "decompression".
My graphs are from an analogue amplifier, digital ones and dsp are probably behaving differently.
Well I can certainly see the value of reducing the dynamics when listening at low levels.
Any idea as to what percentage of compression is optimal?
Any idea as to what percentage of compression is optimal?
You are welcome Carl. I placed a small value cap (200-500pf) across the top half of the pot as I remember, this was to give some high end boost to more closely match the Fletcher curves of our hearing. Here is another link that you might like.
https://www.extron.com/article/loudnesscontrol_ts
Please keep the URLs coming. Ideally this thread will become a reference warehouse of information.
Ok, here is another site on the loudness control.
https://diyaudioprojects.com/mirror/members.aol.com/sbench/freqres3.html
https://diyaudioprojects.com/mirror/members.aol.com/sbench/freqres3.html
You will have to scroll down a bit to get to the loudness part of this article. It even has tube loudness circuit design!
https://www.tubecad.com/2021/08/blog0542.htm
https://www.tubecad.com/2021/08/blog0542.htm
Hello Forum Members,
Excuse my ignorance, I am somewhat new to diy audio. (I've built 3 preamp/amp projects successfully).
I know this will be child's play for most of you; can anyone point me in the direction of a quality pcb for a passive, three band tone control I could incorporate into a preamp build? I've seen several on sites such as Amazon but am unsure of the quality. Additionally, many of them are active circuits incorporating a volume control that would be redundant in that situation.
I am asking for my own purposes. But am hoping any responses will be helpful to others as well. Thank you in advance.
Excuse my ignorance, I am somewhat new to diy audio. (I've built 3 preamp/amp projects successfully).
I know this will be child's play for most of you; can anyone point me in the direction of a quality pcb for a passive, three band tone control I could incorporate into a preamp build? I've seen several on sites such as Amazon but am unsure of the quality. Additionally, many of them are active circuits incorporating a volume control that would be redundant in that situation.
I am asking for my own purposes. But am hoping any responses will be helpful to others as well. Thank you in advance.
Usually the tone control circuits include some sort of active (buffer/amplifier) stage - why do you think you can get away with a passive one?
And why do you think three (peaking, at least for the mid band) bands would be better then two shelving bands?
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@madis64
I'm not trying to "get away" with anything. As I said, I am fairly new to diy electronics, and as such, have limited knowledge of circuitry.
I am looking for something simple, that works. I'm not looking for some complex circuit with exotic parts and elaborate capabilities. Perhaps such a pcb does not exist. That might explain why I am having trouble finding one. I thought it was worth asking.
As far as why I was looking for a three band option, I prefer three bands.
I'm not trying to "get away" with anything. As I said, I am fairly new to diy electronics, and as such, have limited knowledge of circuitry.
I am looking for something simple, that works. I'm not looking for some complex circuit with exotic parts and elaborate capabilities. Perhaps such a pcb does not exist. That might explain why I am having trouble finding one. I thought it was worth asking.
As far as why I was looking for a three band option, I prefer three bands.
Yet you are discarding the boards sold at Amazon etc.
So the question is - what would it take to elevate the pcb/circuit to acceptable level?
As a workaround - find a broken amplifier in eBay with three band tone control and take the circuit/board from there. 😉
Edit:
Or you can buy the board only:
https://www.ebay.de/itm/225029060323
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This might be a good volume control to build a loudness network around.
The circuit is an active balanced volume circuit that supports a customizable log curve. If one wishes to use the circuit unbalanced, they also may do so. The key point is its excellent attenuation behavior for low listening levels. This was meant to address the sensitivity problem that several builders in the Preamp from Linear Audio # 5 thread had noted. The circuit shown below offers a truer curve than a linear pot with a resistor from wiper to ground, and is better early in the rotation than many expensive audio taper log potentiometers that I've measured, and it has a constant input impedance.
The 10k potentiometer is the volume control. The 11k and 470R resistors allow fine tuning of the log curve and one could be replaced with a multiturn trimmer pot; higher combines values (a single resistor can be used, if you wish) result in a more linear curve; and lower values exaggerate the log shape of curve.
The circuit is an active balanced volume circuit that supports a customizable log curve. If one wishes to use the circuit unbalanced, they also may do so. The key point is its excellent attenuation behavior for low listening levels. This was meant to address the sensitivity problem that several builders in the Preamp from Linear Audio # 5 thread had noted. The circuit shown below offers a truer curve than a linear pot with a resistor from wiper to ground, and is better early in the rotation than many expensive audio taper log potentiometers that I've measured, and it has a constant input impedance.
The 10k potentiometer is the volume control. The 11k and 470R resistors allow fine tuning of the log curve and one could be replaced with a multiturn trimmer pot; higher combines values (a single resistor can be used, if you wish) result in a more linear curve; and lower values exaggerate the log shape of curve.
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There is a little bit of work to be done to use a 5k or less pot, to lower the gain and alter the 11k/470R.
Fisher was another company that used the inverse loudness contour on the volume pot. It only boosted the bass.
I spent a couple of hours modeling my proposed loudness control in my ancient copy of Circuit Maker software. Below is the result. R32 and R33 pots (circled in red) form the contour control. The pot segments are wired opposite of one another so that the resistance increases on one while reducing on the other. A four gang pot is required for 2 channel stereo. Rotating the contour pot counterclockwise 100% passes only the unequalized signal and none of the loudness corrected signal. As you rotate the contour pot clockwise the ratio of equilized to unequalized signal increases. The gain and slope frequencies are adjustable for both the 'Hi' and 'Lo' portions of the loudness correction. My goal was to make all elements adjustable, at least for the prototype. The loudness EQ portion of the shown filter circuit is lifted from the recent article in AudioXpress by Douglas Self.
I have not actually built the circuit. I've only knocked it up in Circuit Maker. Circuit Maker predicts the filter behavior shown below. Assuming that I have time, I plan to build it during the holiday break. I invite any and all interested parties to make comments.
I have not actually built the circuit. I've only knocked it up in Circuit Maker. Circuit Maker predicts the filter behavior shown below. Assuming that I have time, I plan to build it during the holiday break. I invite any and all interested parties to make comments.
