Digital Phono Pre-Amplifier- Anybody interested?

[reubensm]

Hello,

There is a lot of response here on the forums for vinyl.
It got me thinking that I could use my digital audio processor and program it for RIAA curve to make a Phono Pre-amp.
Does it sound interesting?
My processor board has 6 outputs and I could output any combination of signals on those. e.g.

1. Lt-Rt, L-R-SW
2. L-R-SW, C-S-SW

I have attached a simulated RIAA response curve for your review. Since the signal is shaped to the required response in digital domain, we don't have to worry about its stability or its accuracy.

Also, since the platform is re-programmable, we could literally customize it to suite the individuals' need.

I could add other processing to bring out the details and the sound stage, if/ as required.

Let me know what you guys feel.

Regards,

Ravindra.

I've been wanting to write for quite a while, out of curiosity. Never thought there could be a digital phono preamp. Never even entertained the thought of using anything digital for listening to records, but after some thought, I cant help but wonder, how is this possible? Could you share some light on this? Also going through your posts, I am sure a lot of stuff what you write about or think about it beyond someone like me, comprehending. Is this your profession and are you from a research background? Just curious.

 

[Ravindra Desai]

I've been wanting to write for quite a while, out of curiosity. Never thought there could be a digital phono preamp. Never even entertained the thought of using anything digital for listening to records, but after some thought, I cant help but wonder, how is this possible? Could you share some light on this? Also going through your posts, I am sure a lot of stuff what you write about or think about it beyond someone like me, comprehending. Is this your profession and are you from a research background? Just curious.

Hello,

Thanks for your kinds words. It inspires me.

The Digital Phono Pre-amp first:

It typically has two parts to it.
1. Gain stage: Since the pick-up signal is few milli-volts, it needs to be amplified to line level (say 250mv to 775mv). This needs to be done before any digitization so that the resolution is not compromised. Hence, this will be in analog domain.
2. RIAA equalization stage: A curve, inverse of that used during recording to get optimum signal to noise ratio. This needs precision components sometimes 2-3 elements in series or parallel to get an EQ that resembles the required curve set by RIAA.

The second part, if done in digital, does not need any precision components, is temperature independent and allows various DSP options simply not possible in analog or using analog circuits.

For the second part:

I am an audio buff and with my engineering background, I like to do things provided math supports it. I don't care of or fear what approach I take as long as the end result is pleasing to the ears.

Thanks again!!

Regards,

Ravindra.

 

[reubensm]

That's a great approach, what matters is how enjoyable the music sounds. Sounds very interesting. If only we can get an opportunity to have a digital phonostage run up against an analog phonostage like say, the CNC. That would be really interesting. Thinking rather ahead, I am sure scratches and rumble can also be filtered digitally. Interesting stuff. How difficult is it to make something digital? I have always stayed away from digital projects due to my inexperience with and phobia against working with surface mounted devices,, though I am aware digital projects can work on bread boards too

 

[Ravindra Desai]

That's a great approach, what matters is how enjoyable the music sounds. Sounds very interesting. If only we can get an opportunity to have a digital phonostage run up against an analog phonostage like say, the CNC. That would be really interesting. Thinking rather ahead, I am sure scratches and rumble can also be filtered digitally. Interesting stuff. How difficult is it to make something digital? I have always stayed away from digital projects due to my inexperience with and phobia against working with surface mounted devices,, though I am aware digital projects can work on bread boards too

I am working on one based on the approach outlined above. I am doing it for my personal need to bring my dead Garrard changer back to life.
I should be able to hear sound somewhere in this month.

Just so that you know, I have crossed boundaries that separates analog, digital, tubes, semiconductors, chip amps, discretes, MOSFETS, BJTs.....
In a blind listening test, no one will be able to tell my system components DNA.

b.t.w. I love fullrange based speaker systems and do not use passive crossovers and never in the vocal range. I have designed the entire electronics signal chain myself.

Do tell me your interests and system details also.

Regards,

Ravindra.

 

[Kannan]

The first time I started dabbling with active setups was when I ventured into car audio.

With speakers placed all over, in doors, in A panels, sub in the boot, acres of glass, plastic all over the dashboard, dirty power, road noise and proximity of the listener to the speakers, makes it a nightmare to get good audio in cars.
Audiophiles shudder at the thought of the term 'audiophile' when one talks about music in cars.

But if done properly it is much more pleasurable and intimate than listening at home, unless one has the luxury of dedicated rooms.

There are some excellent active head units, and nowadays with lots of integration with OE head units, Digital Sound Processors (DSP) have taken the place of active head units.

Some of the audiophile grade active head units include Clarion HX-D2, HX-D3, Pioneer P99RS, Pioneer 80PRS and its iterations and the Eclipse CD7200 mkii. All these are single din HUs.
Some great features offered by some of these head units include excellent DACs, full copper chassis, isolated power supplies, 6/8 channel outputs, powerful processing features like setting varieties of crossovers, slope, time alignment of individual drivers, delay, attenuation, phase change and so on.
In addition these HUs came with Parametric or upto 32 band graphic equalizer which could be applied to each of its 6/8 outputs.
All the processing ofcourse happen in the digital domain.

However these head units have almost hit the dust after car companies started to offer lots of integration features in the OE head units leading to development of outboard Digital Signal Processors with both analogue and digital inputs.

The only caveat of active setup is that you need amplification for each channel....8 channel or 4-way active setup (tweeter, midrange, woofer, subwoofer) means 3 stereo amps and one monoblock....6 channel or 3-way active setup (tweeter, woofer, subwoofer( meants 2 stereo amps and a monoblock.

It gives immense flexibility at the users hand and is an excellent learning curve to understand what each octave does to the overall music.

Though initially I dabbled a lot with measurements etc., I soon decided the best way to tune is with ones ears, after all music is heard and not seen.

At one point, I was running Class A amp into tweeters, Class AB into the midrange and Class D into the midbass and subwoofer in my car.

But now I have a much more simple 4-way active setup with all Class D plam size TDA3118 amps.

I also wonder why this fixation even among high end companies which keep stating 'Out reference solid state amp sounds like tube'....why the hell then make it SS, better stick to tubes.

@Ravindra Desai Sorry for this long post sir, just highlighting that DSPs are truly the way to go, especially with power amps getting so cheap.

 

[tuff]

@Ravindra Desai Make one. I shall be your first customer. Just got a turntable, and need a decent phono amp. Roll up them sleeves.

 

[Ravindra Desai]

@Ravindra Desai Make one. I shall be your first customer. Just got a turntable, and need a decent phono amp. Roll up them sleeves.

Turntable & Magnepans just made a case for 2nd Thane visit!
I'll call you in the morning.

Regards,

Ravindra.

 

[Kannan]

Turntable & Magnepans just made a case for 2nd Thane visit!
I'll call you in the morning.

Regards,

Ravindra.

I salute you Mumbaikars for the passion.

Salutations.

 

[Ravindra Desai]

The first time I started dabbling with active setups was when I ventured into car audio.

With speakers placed all over, in doors, in A panels, sub in the boot, acres of glass, plastic all over the dashboard, dirty power, road noise and proximity of the listener to the speakers, makes it a nightmare to get good audio in cars.
Audiophiles shudder at the thought of the term 'audiophile' when one talks about music in cars.

But if done properly it is much more pleasurable and intimate than listening at home, unless one has the luxury of dedicated rooms.

There are some excellent active head units, and nowadays with lots of integration with OE head units, Digital Sound Processors (DSP) have taken the place of active head units.

Some of the audiophile grade active head units include Clarion HX-D2, HX-D3, Pioneer P99RS, Pioneer 80PRS and its iterations and the Eclipse CD7200 mkii. All these are single din HUs.
Some great features offered by some of these head units include excellent DACs, full copper chassis, isolated power supplies, 6/8 channel outputs, powerful processing features like setting varieties of crossovers, slope, time alignment of individual drivers, delay, attenuation, phase change and so on.
In addition these HUs came with Parametric or upto 32 band graphic equalizer which could be applied to each of its 6/8 outputs.
All the processing ofcourse happen in the digital domain.

However these head units have almost hit the dust after car companies started to offer lots of integration features in the OE head units leading to development of outboard Digital Signal Processors with both analogue and digital inputs.

The only caveat of active setup is that you need amplification for each channel....8 channel or 4-way active setup (tweeter, midrange, woofer, subwoofer) means 3 stereo amps and one monoblock....6 channel or 3-way active setup (tweeter, woofer, subwoofer( meants 2 stereo amps and a monoblock.

It gives immense flexibility at the users hand and is an excellent learning curve to understand what each octave does to the overall music.

Though initially I dabbled a lot with measurements etc., I soon decided the best way to tune is with ones ears, after all music is heard and not seen.

At one point, I was running Class A amp into tweeters, Class AB into the midrange and Class D into the midbass and subwoofer in my car.

But now I have a much more simple 4-way active setup with all Class D plam size TDA3118 amps.

I also wonder why this fixation even among high end companies which keep stating 'Out reference solid state amp sounds like tube'....why the hell then make it SS, better stick to tubes.

@Ravindra Desai Sorry for this long post sir, just highlighting that DSPs are truly the way to go, especially with power amps getting so cheap.

Thank you for the long post!
There are so many finer points in there.....

Designing DSP is one thing but to be able to use it is another. Most people mess up if they are given a three band equalizer instead of bass and treble controls and you have mastered the art of equalizing multi-way set up. That is a huge achievement and a very unique skill. As you rightly mentioned it tells you what each octave does and its place and weight in the entire spectrum.

I have seen engineers use pink noise generators and spectrum analyzers and what not and take upto 6-8 hours to tune one projector and I have seen some do it in 45mins and use the instruments only to confirm the correctness.

Couple of weeks back I met a group of car audio fanatics. They were impressed by my sound and wanted me to do the same in their cars.
It should not surprise you that my sound profile failed miserably in the car. It took me a while to understand what is going on. When time permits, I will have to work on it and develop a completely new profile for car.

@Ravindra Desai Make one. I shall be your first customer. Just got a turntable, and need a decent phono amp. Roll up them sleeves.

I'll send you my big stereo amp today. See if it moves the Magnepans enough and if its any different from the Crown XLS1502.
Then I'll come over with my DSP with a separate phono stage added and we'll get into customization, if needed.

Well, let's keep it up and not forget to enjoy the sound of music.

Regards,

Ravindra.

 

[dillihifi]

I am also interested in your products, if possible could you kindly indicate what would be the ballpark price for an MC phono preamp.

 

[reubensm]

Hello again, recently I came across the sugarcube sweet vinyl video demo on youtube. Is it possible to design something like this with an algorithm similar to what is used in typical vinyl ripping software with clicks and pops removal?

Sugarcube Sweet Vinyl