Hi. After an exhaustive search of this and other forums' discussions on loudness, loudness circuits, PCBs and kits and not finding much that I can understand, I conclude that I need some help.
I'm seeking a standalone variable loudness compensation control that can sit between my pre-amp and amp and can handle two channels and a sub. Preferably passive with a bypass switch. I've read through a lot of loudness threads here and on other sites and it has become apparent that I don't know enough to read a circuit diagram, understand how good of an implementation any given design is, how modify a design for my purposes and put a complete BOM together. My experience is limited to assembling kits with PCBs. Is there a kit for this somewhere? If not, does anyone know of a BOM? I might be able to figure out how to do this point-to-point or find someone to make a one-off PCB (if that's a thing).
Thanks in advance for any guidance you can provide!
Aaron
I'm seeking a standalone variable loudness compensation control that can sit between my pre-amp and amp and can handle two channels and a sub. Preferably passive with a bypass switch. I've read through a lot of loudness threads here and on other sites and it has become apparent that I don't know enough to read a circuit diagram, understand how good of an implementation any given design is, how modify a design for my purposes and put a complete BOM together. My experience is limited to assembling kits with PCBs. Is there a kit for this somewhere? If not, does anyone know of a BOM? I might be able to figure out how to do this point-to-point or find someone to make a one-off PCB (if that's a thing).
Thanks in advance for any guidance you can provide!
Aaron
I saw that one. It's a little confusing because they say "volume control" which from the description I take to mean a variable control of the curve and not the volume of the music. So, for my purposes I would buy two and also get a 12V power supply with a momentary switch to switch the loudness off and on to both modules simultaneously. I get 8 RCA enclosure mountable jacks for L R and Sub1 Sub2 inputs/outputs, two knobs, an adequately sized enclosure with some kind of mount for that board, and an enclosure mountable power supply jack. Correct? Any amperage for the power supply?
Thanks!
Thanks!
Ah. Then this device sort of assumes a certain level of amplification and sensitivity downstream. That wouldn't work for my application, unfortunately. I've been seeing this as a criticism of loudness buttons on integrated amps in the past: that they assume speaker sensitivity. The current Yamaha A-S series of amplifiers have a variable loudness knob. The easiest solution would be for me to get one of those, sell my power amp and I'm done. It's less fun though.
Hi Aaron. You are encountering the same issues I have in my similar loudness control endeavor. Hopefully I can help by sharing my experience.
Basically, there are two impediments to successfully implementing a loudness control: 1) Loudness controls are incorrectly lumped in the same category as tone controls and as such are eschewed by “purists”. OTOH, Folks who want to achieve spectral balance at less-than-reference listening levels (ie what a loudness control does) often find it simpler to adjust by ear using standalone EQ which leads to 2) Loudness controls are difficult to implement because doing so in an ideal fashion requires correct gain staging. Put simply, for a loudness control to work according to theory, one has to make sure the 0dB setting on a loudness control/attenuator delivers the same absolute in-room acoustic level regardless of what source is selected. This is an issue that must be corrected “upstream” of the loudness control, by adjusting the gain of all source components to be equal. Loudness control theory also dictates that such a system requires recalibration anytime a power amplifier and/or loudspeaker change is made. This is because different power amplifiers have different levels of gain and the more obvious issue of different loudspeakers having different levels of sensitivity (ie. acoustic SPL at a given voltage). This requires that gain adjustments can be made downstream of the loudness control/attenuator, such as at the input of the power amplifier.
You can now see how the number of gain controls has multiplied considerably and also how developing a one-size-fits-all kit would prove daunting. There’s also the issue of throwing away gain left and right simply to fit a loudness control into the paradigm. There really isn’t a free lunch here.
My solution was to purchase a through-hole stepped attenuator (Goldpoint) that I could populate myself according to prior loudness attenuator projects I had researched. This attenuator would be sandwiched between the most transparent buffers I could afford, such as the ones made by Neurochrome. My total number of buffers is four; one for each of my three sources and one post-attenuator buffer. Between the three input buffers and my attenuator is a selector switch for source selection. Source level equalization is to be made via gain adjustment of the input buffers. Power amplifier/loudspeaker gain compensation is to be made with a gain selector switch wired to the gain setting resistor eyelets of the post-attenuator output buffer.
0dB on the loudness attenuator will be calibrated at the main listening position using pink noise and a SPL meter on the C-weighted setting. The target SPL is 83dB per speaker, or 86dB when calibrating in stereo.
Another alternative is integrate software-based controls into the system which can approximate target loudness curves in a continuous manner digitally.
hope this helps.
Basically, there are two impediments to successfully implementing a loudness control: 1) Loudness controls are incorrectly lumped in the same category as tone controls and as such are eschewed by “purists”. OTOH, Folks who want to achieve spectral balance at less-than-reference listening levels (ie what a loudness control does) often find it simpler to adjust by ear using standalone EQ which leads to 2) Loudness controls are difficult to implement because doing so in an ideal fashion requires correct gain staging. Put simply, for a loudness control to work according to theory, one has to make sure the 0dB setting on a loudness control/attenuator delivers the same absolute in-room acoustic level regardless of what source is selected. This is an issue that must be corrected “upstream” of the loudness control, by adjusting the gain of all source components to be equal. Loudness control theory also dictates that such a system requires recalibration anytime a power amplifier and/or loudspeaker change is made. This is because different power amplifiers have different levels of gain and the more obvious issue of different loudspeakers having different levels of sensitivity (ie. acoustic SPL at a given voltage). This requires that gain adjustments can be made downstream of the loudness control/attenuator, such as at the input of the power amplifier.
You can now see how the number of gain controls has multiplied considerably and also how developing a one-size-fits-all kit would prove daunting. There’s also the issue of throwing away gain left and right simply to fit a loudness control into the paradigm. There really isn’t a free lunch here.
My solution was to purchase a through-hole stepped attenuator (Goldpoint) that I could populate myself according to prior loudness attenuator projects I had researched. This attenuator would be sandwiched between the most transparent buffers I could afford, such as the ones made by Neurochrome. My total number of buffers is four; one for each of my three sources and one post-attenuator buffer. Between the three input buffers and my attenuator is a selector switch for source selection. Source level equalization is to be made via gain adjustment of the input buffers. Power amplifier/loudspeaker gain compensation is to be made with a gain selector switch wired to the gain setting resistor eyelets of the post-attenuator output buffer.
0dB on the loudness attenuator will be calibrated at the main listening position using pink noise and a SPL meter on the C-weighted setting. The target SPL is 83dB per speaker, or 86dB when calibrating in stereo.
Another alternative is integrate software-based controls into the system which can approximate target loudness curves in a continuous manner digitally.
hope this helps.
Yes I think you're right. TBH, I've never heard a loudness control that worked. Yamaha is an exception, but unless you have some sort of calibration I find it's just a midrange knob. Loudness button on an old 70's POS stereo was basically "bass and treble boost" to me - it didn't seem to vary with volume - especially when the amp would clip at 1/4 volume with a modern source.
Broskie wrote about his idea of a "high end loudness control" --> https://www.tubecad.com/2021/08/blog0542.htm
https://www.ebay.com/itm/312652559182
Look around, they have them with 100k pots as well. None say what the input / driving Z is. None have a dedicated subwoofer output.
It's a starting point. At $15 a pop, I'd expect you could try more than one to see which works out best. Hmmm, this one (https://www.ebay.com/itm/265474973540) has a stepped potentiometer, 100k though. You can even get a vintage unit in this listing https://www.ebay.com/itm/255021296717 and here https://www.ebay.com/itm/133860758124.
Unfortunately, I couldnt find a "plug 'n play" finished product for your specific situation.
Look around, they have them with 100k pots as well. None say what the input / driving Z is. None have a dedicated subwoofer output.
It's a starting point. At $15 a pop, I'd expect you could try more than one to see which works out best. Hmmm, this one (https://www.ebay.com/itm/265474973540) has a stepped potentiometer, 100k though. You can even get a vintage unit in this listing https://www.ebay.com/itm/255021296717 and here https://www.ebay.com/itm/133860758124.
Unfortunately, I couldnt find a "plug 'n play" finished product for your specific situation.
Loudness controls with HF boost compensation seem unnecessary; the delta is just not that great IMO. Yes, over a 40dB range there is a few dB of perceived change of loudness at 10kHz but anything more than that and the loudness control is asking to become abused as a quasi-smiley-face EQ knob. Which is perhaps why they fell out of favor among purists.
There was a german diy-shop, http://www.thel-audioworld.de/ who claimed he had the loudness-control module.
It looks like mr. Thel has retired, and the folks running the shop don’t offer it anymore. But I haven’t investigated the matter ans so I don’t know the present situation there. Maybe, with luck and charme…
It looks like mr. Thel has retired, and the folks running the shop don’t offer it anymore. But I haven’t investigated the matter ans so I don’t know the present situation there. Maybe, with luck and charme…
Wow. That looks spot on. I trust given Broskie's expertise, that the circuit below would be a good one to try to build. I might be able to figure out a point-to-point assembly of his diagram with switches. I'm guessing that I'd need to do this three times. One for L, one for R and one for the Sub. The trouble is, I don't know exactly what to buy.
It's unclear to me whether those are independent variable loudness pots or combo volume & loudness pots.
There seem to be many implementations for Loudness and Tone boost.
In the process of collecting as many as I can.
In particular I am keen on the implementations made on old Akai Amps from the late 70s early 90s.
These worked with a simple on/off switch. i.e. push it in to activate and push it again to turn it off.
If anybody has a collection of loudness circuits pls share. Is there a universal standard which explains what the perfect loudness circuit does.
In the process of collecting as many as I can.
In particular I am keen on the implementations made on old Akai Amps from the late 70s early 90s.
These worked with a simple on/off switch. i.e. push it in to activate and push it again to turn it off.
If anybody has a collection of loudness circuits pls share. Is there a universal standard which explains what the perfect loudness circuit does.
Not to butt in here, but I do remember Yamaha using a loudness control that worked on reducing the midrange and leaving the bass and treble alone. Rather than boost, there was cut, making for less distortion. It was not an on/off circuit but variable at any volume IIRC. Made the most sense to me, and I used it occasionally with the modest but musical 2020 (20 WPC) model way back when.
This has been discussed:
https://www.diyaudio.com/community/...ndependent-loudness-effect-what-rules.365053/
https://www.diyaudio.com/community/...ndependent-loudness-effect-what-rules.365053/
Attachments
Here is one more option I found.
https://www.eleccircuit.com/audio-loudness-control/
I have a doubt. He uses a special trim pot with 8 pins. There is a link in there to amazon but the trim pot costs 75$.
My question is why cant I used a regular double gang trim pot Or no trim pot at all.
https://www.eleccircuit.com/audio-loudness-control/
I have a doubt. He uses a special trim pot with 8 pins. There is a link in there to amazon but the trim pot costs 75$.
My question is why cant I used a regular double gang trim pot Or no trim pot at all.
How did I miss this?
There were a few "variable loudness" controls back in the day. I have a Nakamichi receiver (in mothballs) that has one that works very well. You set the volume control for a typical volume level (86 dB was mentioned in this thread) and then dialed in the loudness compensation. It's pretty much "set and forget."
It is true that gain structure must be optimized for it to work properly. Most "loudness controls" I have encountered have way too much boost in the bass register. The only way to adjust the gain structure would have been to use less efficient speakers.
I worked on this problem for a while, emulating circuits from commercial units and trying an active summing circuit. The only suitable circuit I found was quite traditional and used old school potentiometers made of unobtanium. However, you can switch an array of networks between the fourth post on those potentiometers for a very useful circuit. Adding a second volume control after the loudness plus buffer(on the back of the unit) to adjust the gain structure makes it work even better.
There were a few "variable loudness" controls back in the day. I have a Nakamichi receiver (in mothballs) that has one that works very well. You set the volume control for a typical volume level (86 dB was mentioned in this thread) and then dialed in the loudness compensation. It's pretty much "set and forget."
It is true that gain structure must be optimized for it to work properly. Most "loudness controls" I have encountered have way too much boost in the bass register. The only way to adjust the gain structure would have been to use less efficient speakers.
I worked on this problem for a while, emulating circuits from commercial units and trying an active summing circuit. The only suitable circuit I found was quite traditional and used old school potentiometers made of unobtanium. However, you can switch an array of networks between the fourth post on those potentiometers for a very useful circuit. Adding a second volume control after the loudness plus buffer(on the back of the unit) to adjust the gain structure makes it work even better.
https://www.radioshack.com/products/radioshack-100k-dual-ganged-stereo-volume-control
It looks like these are still available. I have a few (from when RS was still a real company) and they're pretty good.
It looks like these are still available. I have a few (from when RS was still a real company) and they're pretty good.