4 ms·

This looks an EE‘s approach who hasn’t had a lot of exposure to speaker design. You need to consider Thiele/Small parameters of the chassis, enclosure volume, b

This looks an EE‘s approach who hasn’t had a lot of exposure to speaker design. You need to consider Thiele/Small parameters of the chassis, enclosure volume, baffle design and a million other factors to design a proper crossover. You can’t just ltspice your crossover and call it a day. VituixCad would be a more appropriate solution. And then you actually have to measure! Replacing and amp and „smart“ crap is easy if there is an analogue crossover you can reverse-engineer, if it was just some DSP things get difficult quickly (unless its just a single broadband chassis, but even then…). And no, you can’t use pre-built „standard“ crossovers or some calculator on a website either. But other than that, nice that he saved some hardware.

ipsum2 2y ago
You seem to be very knowledgeable about this subject. I have some Google Nest Audio speakers that sound fantastic, but have the same problems as bluetooth speakers, and lack a 3.5mm input jack to convert into normal speakers. Do you have any recommendations on how to do this, for someone with minimal audio knowledge and some basic EE?
- deleted 2y ago
  [deleted]
- liminalsunset 2y ago
  The Google Nest Audio speakers are kind of a special case. They only sound good because they use a sealed, extremely rigid cast aluminum sealed enclosure with a high excursion driver. The performance of these speakers with a regular crossover and amp will be poor, due to the low efficiency of the enclosure/small driver. To get around this, Google put in the TI TAS5825M smart audio amp. By measuring the speaker parameters through V/I measurement and a model, it drives the speaker in a closed loop way with far more power than it would actually be able to handle nornally to compensate for the resistance from the enclosure air pressure, and throttles to maintain the coil at a safe temperature. The chip also does DSP to compress the audio signal, cutting the peaks off the bass as needed when the volume is turned up so volume is maintained at the cost of bass. One way to explore could be to just feed I2S audio from an I2S ADC i.e. PCM1808 to the digital input of the amplifier. The processing is internal to the amp so theoretically you won't lose the tuning. However this may turn out to be a relatively annoying reverse engineering project with fine magnet wire involved. Note: I2S is different from I2C - the amp will likely have both. You will likely need to keep the original system around to program the amp over I2C (or capture the transaction and replay it) - otherwise you will likely get no audio. The "raw" audio performance of this device (just an amplifier connected directly to the internal speaker and dsp on the computer) is impressive, kicking out bass down to 40Hz. It will, however, not last long like that. Reports online are that these blow speakers easily even when used with the default amplifier. I would recommend that if 3.5mm input is desired, to replace them altogether with the IK Multimedia iLoud Micro Monitors. These have sound quality just as good as the Google at similar size, with the same DSP tricks, but have regular inputs and no smart features.
  - ipsum2 2y ago
    Thanks for the comprehensive answer, I'll look into the I2S audio solution. You're right that iLoud Micros sound similar, they're 3x the price (The Nest Audios were sold at $50/each on sale). Definitely worth it, I just like tinkering with things.
encom 2y ago
>You can’t just ltspice your crossover and call it a day. I'm sure that's true, but how important is that really for a set of crappy plastic speakers?
- MrBuddyCasino 2y ago
  At the end of the day, if you're happy and it sounds ok: thats fine, most people can't tell the difference anyway or they get used to however it sounds. But it will inevitably leave a lot of potential performance on the table.
AstroNoise58 2y ago
Do not underestimate audio circuit tuning based on listening tests. Good ears and patience can substitute a lot of lab equipment dollars, especially for a hobbyist.
- MrBuddyCasino 2y ago
  I would say its the precise inverse: very few people can do it well by ear, and it takes a lot of practise and experimentation. At the most basic, try matching the volume level of a subwoofer to the main speakers - even this is already very hard to do by ear, for reasons of human auditory perception and psychoacoustics. You don't even need a lot of "lab equipment dollars", measuring the basics can be done with ~100€ calibrated USB mic. As a rule of thumb, you cannot develop a good speaker without measuring, unless you have advanced modelling tools and experience to use them correctly, in which case the measurements will mostly match the simulations.
  - AyyEye 2y ago
    The best acoustic devices in the world have been made and tuned by hand for thousands of years. "you cannot develop a good speaker without measuring, [modelling, or simulations]." Is fundamentally untrue despite what the cybernetic totalists may want to believe.
    - BoingBoomTschak 2y ago
      >The best acoustic devices in the world have been made and tuned by hand for thousands of years. Says who? You should really acquaint yourself with current research, starting with Toole's infamous "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms".
      - vile_wretch 2y ago
        > Says who? Anyone who has read about or experienced instruments and music halls that were made before the commodification of electricity?
seba_dos1 2y ago
> You can’t just ltspice your crossover and call it a day Turns out you can, they just did and are happy with the results.
- stefan_ 2y ago
  Truly. When will audiophiles get over their depression and realize we solved audio like 30 years ago? Sorry, silicon got too powerful and too good, audio was just no match.
  - MrBuddyCasino 2y ago
    This is kind of true, yet it is not the case that those competently designed speakers dominate the market. It is dominated by awful Bluetooth boxes, terrible headphones and expensive snake oil. Which means most people can’t tell the difference. This is mildly upsetting to the people who can.
amelius 2y ago
Do you know of a way to convert a measured speaker model into a spice model that can be simulated with the rest of the circuit?

ipsum2 2y ago

You seem to be very knowledgeable about this subject. I have some Google Nest Audio speakers that sound fantastic, but have the same problems as bluetooth speakers, and lack a 3.5mm input jack to convert into normal speakers. Do you have any recommendations on how to do this, for someone with minimal audio knowledge and some basic EE?

deleted 2y ago
[deleted]
liminalsunset 2y ago
The Google Nest Audio speakers are kind of a special case. They only sound good because they use a sealed, extremely rigid cast aluminum sealed enclosure with a high excursion driver. The performance of these speakers with a regular crossover and amp will be poor, due to the low efficiency of the enclosure/small driver. To get around this, Google put in the TI TAS5825M smart audio amp. By measuring the speaker parameters through V/I measurement and a model, it drives the speaker in a closed loop way with far more power than it would actually be able to handle nornally to compensate for the resistance from the enclosure air pressure, and throttles to maintain the coil at a safe temperature. The chip also does DSP to compress the audio signal, cutting the peaks off the bass as needed when the volume is turned up so volume is maintained at the cost of bass. One way to explore could be to just feed I2S audio from an I2S ADC i.e. PCM1808 to the digital input of the amplifier. The processing is internal to the amp so theoretically you won't lose the tuning. However this may turn out to be a relatively annoying reverse engineering project with fine magnet wire involved. Note: I2S is different from I2C - the amp will likely have both. You will likely need to keep the original system around to program the amp over I2C (or capture the transaction and replay it) - otherwise you will likely get no audio. The "raw" audio performance of this device (just an amplifier connected directly to the internal speaker and dsp on the computer) is impressive, kicking out bass down to 40Hz. It will, however, not last long like that. Reports online are that these blow speakers easily even when used with the default amplifier. I would recommend that if 3.5mm input is desired, to replace them altogether with the IK Multimedia iLoud Micro Monitors. These have sound quality just as good as the Google at similar size, with the same DSP tricks, but have regular inputs and no smart features.
- ipsum2 2y ago
  Thanks for the comprehensive answer, I'll look into the I2S audio solution. You're right that iLoud Micros sound similar, they're 3x the price (The Nest Audios were sold at $50/each on sale). Definitely worth it, I just like tinkering with things.

encom 2y ago

>You can’t just ltspice your crossover and call it a day. I'm sure that's true, but how important is that really for a set of crappy plastic speakers?

MrBuddyCasino 2y ago
At the end of the day, if you're happy and it sounds ok: thats fine, most people can't tell the difference anyway or they get used to however it sounds. But it will inevitably leave a lot of potential performance on the table.

AstroNoise58 2y ago

Do not underestimate audio circuit tuning based on listening tests. Good ears and patience can substitute a lot of lab equipment dollars, especially for a hobbyist.

MrBuddyCasino 2y ago
I would say its the precise inverse: very few people can do it well by ear, and it takes a lot of practise and experimentation. At the most basic, try matching the volume level of a subwoofer to the main speakers - even this is already very hard to do by ear, for reasons of human auditory perception and psychoacoustics. You don't even need a lot of "lab equipment dollars", measuring the basics can be done with ~100€ calibrated USB mic. As a rule of thumb, you cannot develop a good speaker without measuring, unless you have advanced modelling tools and experience to use them correctly, in which case the measurements will mostly match the simulations.
- AyyEye 2y ago
  The best acoustic devices in the world have been made and tuned by hand for thousands of years. "you cannot develop a good speaker without measuring, [modelling, or simulations]." Is fundamentally untrue despite what the cybernetic totalists may want to believe.
  - BoingBoomTschak 2y ago
    >The best acoustic devices in the world have been made and tuned by hand for thousands of years. Says who? You should really acquaint yourself with current research, starting with Toole's infamous "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms".
    - vile_wretch 2y ago
      > Says who? Anyone who has read about or experienced instruments and music halls that were made before the commodification of electricity?

seba_dos1 2y ago

> You can’t just ltspice your crossover and call it a day Turns out you can, they just did and are happy with the results.

stefan_ 2y ago
Truly. When will audiophiles get over their depression and realize we solved audio like 30 years ago? Sorry, silicon got too powerful and too good, audio was just no match.
- MrBuddyCasino 2y ago
  This is kind of true, yet it is not the case that those competently designed speakers dominate the market. It is dominated by awful Bluetooth boxes, terrible headphones and expensive snake oil. Which means most people can’t tell the difference. This is mildly upsetting to the people who can.

amelius 2y ago

Do you know of a way to convert a measured speaker model into a spice model that can be simulated with the rest of the circuit?