All right. I'm beginning to see I am out of touch with the goals of this thread. My bad.
Forget the 24-bit DAC. How about analogue tone controls and one of those handy "loudness" buttons? Remember the loudness button?!! These will also coordinate with that retro DIN socket.
Am I back on plan now?
Forget the 24-bit DAC. How about analogue tone controls and one of those handy "loudness" buttons? Remember the loudness button?!! These will also coordinate with that retro DIN socket.
Am I back on plan now?
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For us oldies what we need is an anti-loudness button. Actually, I'm not joking as much as you might think. My ears get irritated by certain frequencies, sibilance and by response peaks in speaker drivers. These unwanted artifacts occur where our ears are more sensitive. I'd actually like to consider a 'De-Ess' circuit rather than a simple tone control. I've never found much use with tone controls in the past. What I would prefer is something more targeted at removing what I don't want to hear. An adjustable EQ, where a couple of bad frequencies can be dialed back is the simplest approach. But I believe this is too simple. It needs to be smarter, some kind of dynamic-EQ or as I said, a De-Esser.
I like the idea of throwing a DAC into the box but there are two issues that arise, a) it needs a low voltage higher current supply which currently isn't in the plans, b) there will be high frequency digital switching noise that must be isolated from the phono amp. It may be possible to install some EM partitions inside the box to keep a small DAC electrically isolated for airborne EM but it needs some more careful engineering to keep switching noise out of the signal and out of the power ground. A rpi-zero-w and DAC would be asking for 200mA at 5V. A DC-DC buck converter hanging off the +36V rail would do that at low cost and efficiently. But can it be kept quiet and clean. A linear regulator would be preferred from a noise perspective, which means burning off at least 6W in the regulator. Perhaps that's OK, bolted to the chassis sidewall.
I like the idea of throwing a DAC into the box but there are two issues that arise, a) it needs a low voltage higher current supply which currently isn't in the plans, b) there will be high frequency digital switching noise that must be isolated from the phono amp. It may be possible to install some EM partitions inside the box to keep a small DAC electrically isolated for airborne EM but it needs some more careful engineering to keep switching noise out of the signal and out of the power ground. A rpi-zero-w and DAC would be asking for 200mA at 5V. A DC-DC buck converter hanging off the +36V rail would do that at low cost and efficiently. But can it be kept quiet and clean. A linear regulator would be preferred from a noise perspective, which means burning off at least 6W in the regulator. Perhaps that's OK, bolted to the chassis sidewall.
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All right. I'm beginning to see I am out of touch with the goals of this thread. My bad.
Forget the 24-bit DAC. How about analogue tone controls and one of those handy "loudness" buttons? Remember the loudness button?!! These will also coordinate with that retro DIN socket.
Am I back on plan now?
NOW YOU ARE TALKING!
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Gareth, you can make a notch control for just about any frequency you want. Are you interested, I will post a typical design. If you recall bass, mid and treble used to be popular in the early Marantz, a tilt control as used by earlier Quad pre-amps is another option. I think AntrewT has a Quad he may indicate how well it does or does not work.
BTW I don't use a hearing aid yet
BTW I don't use a hearing aid yet
Regarding the DAC problem that you foresee, If you need quiet then follow your SMPS with a linear regulator. I am not sure why audio guys are so anti-switchers, a DAC is exactly that, a switching device, there is nothing linear about it. Besides a SMPS can be made to switch many times higher that a DAC why would there be artifacts in the audio range. 100 Hz is much more troublesome as the fundamental and all the harmonics are distributed over your audio band. Besides, diodes switch the mains in your linear supply.....
Believe me, you will be alright using a simple switching power supply, they are a dime a dozen on eBay and it is made already.
Believe me, you will be alright using a simple switching power supply, they are a dime a dozen on eBay and it is made already.
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What I expect will be handy is the option to tune down at least two frequencies by different amounts. These frequencies will likely coincide with where my ear is most sensitive to annoyances. I believe we evolved to be particularly sensitive to baby screams etc. And our ear canals have self resonance peaks in this area. The frequencies of interest are in the presence region, say 1kHz to 7kHz.
Most midwoofers are crossed above 1 kHz and almost all these midwoofers have problem at around 1 kHz to 1.2 kHz. If we create a notch around this frequency it will help sensitive ears. This isnt a common solution but it is effective for me but i do it at speaker level not in electronics.
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Yes, speakers - another source of irritant sounds.
For these issues I don't think tone controls will do. We need better tools in our preamps for dealing with the vagaries of recording technique, mixing and production, reproduction, room effects, our ears etc.
Any good quality circuit options for two-band dynamic EQ ?
For these issues I don't think tone controls will do. We need better tools in our preamps for dealing with the vagaries of recording technique, mixing and production, reproduction, room effects, our ears etc.
Any good quality circuit options for two-band dynamic EQ ?
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Here's a passive solution to the anti-loudness control, but probably too simple for dealing with annoyances: The Delicious One - Delicious Decibels
I could have written all of that. My speakes are a bit raw. Colleen prefers the sound that way. Little fixes I have done to the phase plugs show how a mix was done. She doesn't like that. I can understand why. My system sounds like a very loud and very open 1960's sound. The one we both would remember. I do fancy that a digital solution would be nice that could process all and everything if I choose. My BBC friend likes the BBC speakers yet has no rose coloured view of them. As she says they make 7 hour shifts at the BBC easier to do. She really loves the ATC speakers, me too. However not for 7 hour shifts. The only problem I find is a resonance is like a crime that never can be hidden. It is better to hide the crime rather than not to try. It never really goes away, it just hides 12 dB down or whatever.
As said before. If the 75 uS is passive you can change it as a free of charge tone control. It could be added to everything and be the useful 200R if not in use. 25 to 100 uS should be useful with a 2 uS option.
Would I be right in thinking even 24 bit is stretched to do this job?
BTW 10 x 10^-3 ohms regualtors are useles if 1 mV of hum is found on the 0V rail.
As said before. If the 75 uS is passive you can change it as a free of charge tone control. It could be added to everything and be the useful 200R if not in use. 25 to 100 uS should be useful with a 2 uS option.
Would I be right in thinking even 24 bit is stretched to do this job?
BTW 10 x 10^-3 ohms regualtors are useles if 1 mV of hum is found on the 0V rail.
I think it is a matter of power and quality. I bought some LED bulbs for my bathroom a few years back from a Chinese supplier at a very reasonable price. Unfortunately, whenever I switched the lights on my FM radio in the kitchen went dead. Major brand bulbs I've tried do not do this.
A SMPS is obviously good for size and efficiency. In general, I would put one in its own metal box and clean up the output with a downstream linear regulator.
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Simply do a before and after regulator test to be certain it isn't worse. If you never had this problem bet others will. The Meanwell SMPS don't seem to enjoy signal and chassis ground connected. I can understand why as the company uses a Y2 cap to take the power terminals to ground. This implies safety issues if an extra path is made.
Hi Traderbaumk, I meant these buck/boost types, not the the stuff for LEDs - remember Garerth wants to drop the 45VDC to lower for the pre-amp. I know some of those Chinese switchers some are very crude, not what I meant - sorry.
Look at these things, that is what I had in mind. Followed by some caps and a linear regulator, it is dead quiet.
DC-DC Boost Buck adjustable step up down Converter XL6009 Module Solar Voltage M | eBay
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Tone Controls
I remember reading on Linkwitz website about how he listened to a swept frequency source to identify ‘annoyances’ in the response of his earphones. I thought I’d give this a go. http://www.szynalski.com/tone-generator/
Interestingly, it was much harder than I thought. With a clean tone generator I found there wasn’t too much to be annoyed about. However, I was able, with some practice and time to sweep back and forth and focus in on areas where it was relatively less ‘nice’.
Interesting to compare with a plot I found on the 'net showing the 'gain' response of the ear.
Seems to me that 'tone' controls might be based on this data more than just 'treble-bass'.
I have also read a few interesting articles/blogs about how people go about mixing music for production. There are a number of cases where the presence region is boosted to give the music a more aggressive tone, especially so-called 'modern' recordings. There are a lot of powerful software tools available now for people to mix music with and thoughts about 'purity of sound' and worrying about capacitor distortion and similar ilk detracting from what the artist intended starts looking really silly when you read what these guys do to the music before it gets distributed.
I remember reading on Linkwitz website about how he listened to a swept frequency source to identify ‘annoyances’ in the response of his earphones. I thought I’d give this a go. http://www.szynalski.com/tone-generator/
Interestingly, it was much harder than I thought. With a clean tone generator I found there wasn’t too much to be annoyed about. However, I was able, with some practice and time to sweep back and forth and focus in on areas where it was relatively less ‘nice’.
Interesting to compare with a plot I found on the 'net showing the 'gain' response of the ear.
Seems to me that 'tone' controls might be based on this data more than just 'treble-bass'.
I have also read a few interesting articles/blogs about how people go about mixing music for production. There are a number of cases where the presence region is boosted to give the music a more aggressive tone, especially so-called 'modern' recordings. There are a lot of powerful software tools available now for people to mix music with and thoughts about 'purity of sound' and worrying about capacitor distortion and similar ilk detracting from what the artist intended starts looking really silly when you read what these guys do to the music before it gets distributed.
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