Adding a 10-band PEQ to a DAC - What is holding manufacturers back?

[EJ3]

I see a smartphone thats optimized for sound in future. Its all there, just a company that likes to serve this market is needet. You have a screen for ui, you have fast cpu and memory. You have programmers that know the os and java. Just add a good dac and good io(hp amp). Sell it as audiophile smartphone. To catch the audiophools sell the golden version.

Now that my wife & I are in the same house again (the pandemic had us on different continents) I have no use case for a phone.

 

[Rednaxela]

Most EQ I have seen have +/- 6db boost/cut on each band. That totally changes the music reproduction. The +/- 0.5 db will ensure that you adjust but don’t change the music.

While preventing someone to do something like this?

 

[KeithPhantom]

Is it too difficult?

No, we have FPGA that can be used for DSP. Chord uses them to make a high-tap anti-imaging/aliasing filter.

Too niche?

Mostly this. The use of EQ has peaked as headphone measurements became more available.

What is it that seems to make a proper stereo DAC with just 7 more bands too much to ask for in 2022?

Why limit yourself to parametric EQ?, you could even pull off some really high-tap convolution filters with the processing power we have available at the sort of power a DAC uses.

 

[Rednaxela]

you could even pull off some really high-tap convolution filters with the processing power we have available at the sort of power a DAC uses.

In a self-contained device?

 

[EJ3]

But rooms do not.

I was referring to "ruler flat" and the person that wants 0.5 Db of adjustment. If rooms were ruler flat, there would not be an issue for many (except to season to taste). Either way, more than 0.5 Db will be needed.

Most EQ I have seen have +/- 6db boost/cut on each band. That totally changes the music reproduction. The +/- 0.5 db will ensure that you adjust but don’t change the music.

My only use case for head phones is cordless headphones so that I can do things with both hands and have music when I am within 30 meters of the stereo.
If I am sitting to do critical listening (unfortunately a precious small amount of time), I am listening to speakers & need to correct so that they sound right in the room. It take more than 0,5 Db to do that.

 

[KeithPhantom]

In a self-contained device?

I use a 1:1 linear-phase convolution filter in Roon (so if my Fs = 44,100 Hz, the filter has 44,100 taps) and it doesn't use 1% of the CPU in an old laptop running at 1.3 GHz. I think an ARM CPU using the Cortex-M architecture could do it as well. As long as you don't use a convolution filter with DSD you are fine.

 

[Rednaxela]

I use a 1:1 linear-phase convolution filter in Roon (so if my Fs = 44,100 Hz, the filter has 44,100 taps) and it doesn't use 1% of the power of the CPU in an old laptop running at 1.3 GHz. I think an ARM CPU using the Cortex-M architecture could do it as well. As long as you don't use a convolution filter with DSD you are fine.

Understood. What I mean is how to offer such functionality without the need for external software (and hardware)?

 

[KeithPhantom]

Understood. What I mean is how to offer such functionality without the need for external software (and hardware)?

You don't need "external hardware" to do such operations unless adding these DSP operations as operating hardware in a DAC, thus effectively creating an audio SoC. DACs are not specialized in these operations (their job is limited to the correct conversion of digital signals into analog signals), and they will need more operating circuitry to achieve this, but I am sure that this can be integrated as part of the package using VLSI techniques.

 

[Rednaxela]

@KeithPhantom

So how will the DAC (+ DSP) know what convolution filter to apply?

 

[KeithPhantom]

@KeithPhantom

So how will the DAC (+ DSP) know what convolution filter to apply?

By sending the filter to the DAC as part of the setup (this can be changed anytime), which will erase some EEPROM and flash it there. Then, just change a register to tell the chip to process the DSP before the conversion into analog. If you want another one, send another filter or maybe get some PROM/NAND storage medium to store multiple filters. All of this can be controlled by a menu like the ones used to change the reconstruction filters.

 

[Rednaxela]

For this sending you need

external software (and hardware)

right?

 

[KeithPhantom]

right?

Yes, like a phone or a computer with an app or a program. But it is a one-time process as long as you do not change the DSP settings. This is with convolution, with parametric EQ you can just use the buttons the DAC brings.

 

[Rednaxela]

Yes, like a phone or a computer with an app or a program. But it is a one-time process as long as you do not change the DSP settings. This is with convolution, with parametric EQ you can just use the buttons the DAC brings.

Thank you. That may be the answer to

Why limit yourself to parametric EQ?

But I’ll think about it some more.

 

[restorer-john]

Ah, nostalgia. Boy did I love those Sony separates with the wooden accents back in the day. Still do.

The TAE-1000ESD was the only Sony ES preamplifier I returned after a weekend loan when it was brand new, 30 years ago. I'd waited for it to be released with baited breath. My dealer rang me and said 'take it home for the weekend' as he was an ES stockist and it was going on the floor anyway.

It sounded dreadful, had an anemic output, and overloaded easily, but was a huge amount of fun to play with. The DSP was half-baked and not in the same league as the Yamaha DSPs of the era. But you could move your seats around in the halls! PEQ was novel and fun at the time.

A mate picked one up recently in mint condition and I tested it. 30 years on. It still sounded dreadful to me and compared to my standalone ES analog preamplifiers, just not in the same league.

 

[poxymoron]

The TAE-1000ESD was the only Sony ES preamplifier I returned after a weekend loan when it was brand new, 30 years ago. I'd waited for it to be released with baited breath. My dealer rang me and said 'take it home for the weekend' as he was an ES stockist and it was going on the floor anyway.

It sounded dreadful, had an anemic output, and overloaded easily, but was a huge amount of fun to play with. The DSP was half-baked and not in the same league as the Yamaha DSPs of the era. But you could move your seats around in the halls! PEQ was novel and fun at the time.

A mate picked one up recently in mint condition and I tested it. 30 years on. It still sounded dreadful to me and compared to my standalone ES analog preamplifiers, just not in the same league.

I imagine there would be a lot of fun to be had with that unit. Disappointed to hear it performed so badly but I guess you should never met your heroes. At least some of the other ES units performed well so the mystique isn't totally shattered.

 

[restorer-john]

I imagine there would be a lot of fun to be had with that unit. Disappointed to hear it performed so badly but I guess you should never met your heroes. At least some of the other ES units performed well so the mystique isn't totally shattered.

Absolutely. The ES range of that era is very well represented in my collection of gear.

 

[Kollin]

Manufacturers of car audio equipment have been producing audio processors with DACs for a long time. I think the main brake on the development of this technology for home DACs is marketers.

Recently I set up a raspberry pi with hifiberry dac and DSP

Let me ask - how did you implement the DSP in this bundle (pi with hifiberry)?

 

[NikJi]

Almost every amplifier ever measured on this forum exhibits a frequency response that is ruler flat throughout the audio band.

And yet some are warmer than others? How?

 

[ROOSKIE]

Most EQ I have seen have +/- 6db boost/cut on each band. That totally changes the music reproduction. The +/- 0.5 db will ensure that you adjust but don’t change the music.

What on Earth are you talking about?

In my room I have several 10db peaks in the bass from room modes.
How is 0.5db going to help.

Or several of the speakers tested here benefit from many adjustments to the responce based on Klippel data, via PEQ, that greatly exceed .5db.

I don't think you are on the right train here.

 

[Chrispy]

What and give up on the straight wire with gain thing? lol