USB-C enough to drive voltage to 1400W active two-way array RCF?

[Regev]

So, I have an RCF Evox 8 active column:

https://www.rcf.it/products/product-detail/-/journal_content/56_INSTANCE_2MT9qNpeXdu4/20195/234072

I want to repurpose my old Pixel 4a as a music streamer for it, and use Tidal Masters quality (9216 kbps - 24-Bit / 192 kHz).

I checked with RCF, they said it was possible, but it depends on my DAC. The Pixel 4a DAC chip is the Qualcomm WCD 9370:

https://www.qualcomm.com/products/wcd9370

Playback Dynamic Range: 120 dB
Total Harmonic Distortion + Noise (THD+N), Playback: -96 dB
Playback Sampling Frequency: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz
Total Harmonic Distortion + Noise (THD+N), Record: -97dB
Recording Sampling: Up to 192kHz/24bit
Recording Dynamic range: 104 dB
Playback Sampling: Up to 192kHz/24bit

Apparently it has enough juice for the Masters quality of TIDAL. Plus I saw here the Pixel 4a's DAC scored a very clean sound (though low output):

Google Pixel 4a Smartphone Audio Review

This is a detailed measurements of the audio performance of the Pixel 4a smartphone. It was kindly purchased new by a member and drop shipped to me. It costs US $350. Being used to my Samsung S8+, the Pixel 4a looks decidedly small: Screen sharpness is much better than above as I left the...

www.audiosciencereview.com

The output of the Pixel 4a through the headphone jack is 0.3v, RCF told me it's not enough for the Evox, and that i'd need a small mixer to increase the voltage output. My question, if I buy the Apple USB-C to 3.5mm adapter reviewed here on AudioScienceReviews, will it output enough juice for the Evox 8?

Another related question, if the default 0.3v through the 3.5mm jack isnt enough, how come I previously managed to output music from the Pixel 4a to the Evox successfully and with enough volume (with a 3.5mm to XLR cable) ? Did I simply miss on sound quality along the way (rather than volume) ? It's strange to me that the voltage matters, since the Evox are connected to the wall and are active, powered.

Thank you in advance.

P.S - as for potential DC offset issues, RCF said "No problem of DC offset. Our input boards are protected from DC."

 

[staticV3]

-RCF Evox 8 input sensitivity is switchable between -2/+4Bu -> 0.6-1.2Vrms. One is Line level, the other is Mic level for directly plugging in dynamic mics. XLR or RCA doesn't seem to matter.
-the Apple A2049 has a maximum output voltage of 1.0Vrms, so you'd be able to saturate the Mic input, but not quite the Line input. A2155 has 0.5Vrms.
-both Apple headphone adapters support a maximum sample rate of 48kHz at 24bit.
-TIDAL Master HiFi may be 24bit, 192kHz, 9000+kbps, but at the end of the day, it is lossy compressed audio. Lossless streaming services exist.

 

[audio2design]

@Regev - the Apple Dongle will default to 50% volume or even less than the output of the 4A. There is no native way to change that. There is a 3rd party program that will fix that and I think it integrates with Tidal. Universal Audio Player Pro. If you have a rooted phone there are more options.

 

[Regev]

-RCF Evox 8 input sensitivity is switchable between -2/+4Bu -> 0.6-1.2Vrms. One is Line level, the other is Mic level for directly plugging in dynamic mics. XLR or RCA doesn't seem to matter.
-the Apple A2049 has a maximum output voltage of 1.0Vrms, so you'd be able to saturate the Mic input, but not quite the Line input. A2155 has 0.5Vrms.
-both Apple headphone adapters support a maximum sample rate of 48kHz at 24bit.
-TIDAL Master HiFi may be 24bit, 192kHz, 9000+kbps, but at the end of the day, it is lossy compressed audio. Lossless streaming services exist.

Let me see please if I understand you,

1. So A2049's 1Vrms is able to saturate the Mic's 0.6Vrms, and most of the Line's 1.2Vrms (but not all of it)?

2. Does the voltage output simply control the 'volume' levels, rather than sound clarity? Cause if sound clarity remains the same, I'd much rather use the default 3.5mm headphone jack port (0.3v), since that way I get a higher sample rate than the 24bit@48hz of Apple adapters, and the output is more than loud enough. I have to turn the volume knob to about 25% of the way, because the Evox is so loud (it's inside my house).

3. I thought Tidal was advertising itself as lossless ? "With our lossless audio experience and high-fidelity sound quality, stream music like you've never heard it before. No compromises. Just pure sound." . If you have a recommendation for another lossless service, by all means fire it my way

Thank you very much.

 

[staticV3]

1. Yes. With the A2049 and the Evox 8 set to Mic sensitivity, you can get the internal Amp to clip.

2. Higher voltage just means more volume. Nothing else.

3. That's the scummy part. Tidal advertised being a lossless, "audiophile" service. After being called out for false advertising, they changed their marketing strategy somewhat and now advertise their service as "better than lossless", whatever that means.
I highly recommend the two-part, technical analysis of Tidal's service and the MQA format that GoldenSound uploaded to YouTube.

 

[Regev]

1. What do you mean by 'to clip'?

2. So if the 0.3v output from the phone's 3.5mm is enough for my volume needs (again, on 0.3v I'm on 25% of the Evox volume knob), there's no reason at all to use the adapter, and in fact I'll get better sound since the 3.5mm sample rate allows 192kHz/24bit rather than Apple's 24bit@48hz?

 

[staticV3]

Exceeding an Amp's input sensitivity will result in a sudden increase of distortion at the Amp's output. That is commonly referred to as clipping.

Sample rate and bit depth are not indicative of sound quality. 192KHz will not sound clearer than 48KHz.

 

[Regev]

Gotcha. Thank you so much.

To make things clear, sound qualityw-wise, should I cancel the A2049 I just ordered and just use the native 3.5mm port if the volume is good enough?

 

[raindance]

If it's loud enough and doesn't sound distorted it's fine!

 

[Regev]

Alright.
If you got a lossless music streaming service you highly recommend, I'd love to hear.

Thanks again.

 

[staticV3]

Alright.
If you got a lossless music streaming service you highly recommend, I'd love to hear.

Thanks again.

I'm using local FLACs for my lossless needs and Spotify for discovery, so don't have any experience with lossless streaming services unfortunately.

 

[Regev]

Guys any idea what the voltage output of the Logitech Audio Bluetooth Receiver is?

Logitech Support + Download

www.logitech.com

 

[raindance]

I use the Emotiva BTR-1 which claims 2 volts output, although it depends on the streaming service and the device playing the music whether you get full scale output or not (but who cares if it's loud enough!).

I suggest you try Amazon music in HD and see if it sounds better to you.

I wouldn't obsess about it.

 

[Skeptischism]

It depends how the volume control is achieved whether it makes a difference. Its a balance

Driving the input to less than the ideal max before clipping means you are not making use of the Signal to noise ratio (SNR) of the amplifier, because the noise level of the phone/dac remains constant, but the level of the signal (peak) is a lower level in comparison to the noise than if it was pushed to its highest nominal level; if that makes sense. This is also the case with the amplifier though. it has its own SNR and if you are only using 25% of the volume level, you arent utilising the amp at its best either. Basically everything performs best at some small amount below max level before clipping. so you can get better dac performance at say 90% volume, but then if you have to turn your amps down, you lose some amplifier performance. Matching these levels for best performance is called Gain staging.

 

[DVDdoug]

Clipping is "overload distortion". Squared-off waves with the tops & bottoms chopped off. It's the most common kind of distortion. You get analog clipping if you try to get 110W out of a 100 Watt amplifier, or if you try to get 2 Volts out of a preamp that can only put-out 1V.

You get digital clipping when you try to higher than you can "count" with a given bit-depth. With digital, 0dBFS (zero decibels full-scale) the digital maximum (with integer formats) so digital dB levels are normally negative and if you try to go over you get digital clipping. The numbers in a 24-bit file are bigger than an 8-bit file, but everything is automatically scaled to match the DAC so a 24-bit file isn't "louder". (With floating-point data, 0dB is 1.0 and for all practical purposes there is no upper or lower limit so the data itself it won't clip.)

Most player software doesn't digitally amplify (usually it just attenuates, but there are some exceptions) so you don't have to worry about digital clipping (assuming you're not starting with a clipped audio file), except if you boost with digital EQ, then you have to watch-out for digital clipping. Or, if you are doing digital audio editing or production you also have to be aware of potential clipping.

You can't actually clip a DAC because the output goes all the way to 0dB, and whatever analog voltage that equates to. There's no real-standard for that... Some DACs put-out higher voltage than others at 0dB. But of course the digital data going into a DAC can be clipped before it's fed-into the DAC (and it's usually converted/scaled to an integer).

 

[AnalogSteph]

You can't actually clip a DAC because the output goes all the way to 0dB,

For the vast majority of them, anyway, though exceptions do exist. (I remember another case of some random Chinese DAC board that would clip at -6 dBFS a few years back, IIRC it was some sort of assembly screwup.)

Virtually all DACs will output up to 0 dBFS, some of them will have enough headroom for intersample-overs up to +2 dBFS and change (classic Cirrus, AKM - everything with built-in ASRC does not qualify, e.g. typical ESS or TI PCM179x), and some deliberately leave headroom up to +3.5 dBFS.

 

[Head_Unit]

the Apple Dongle will default to 50% volume

Explain more please? That might explain a few things where I couldn't get much volume

 

[Head_Unit]

a lossless music streaming service you highly recommend, I'd love to hear.

Apple Music...not really. Occasional static blasts when something screws up-in my AirPods pro and AirPods and today on Bluetooth speakers. Sometimes shows playing but no sound. Sometimes won't load an album from a search. These problems have persisted through various versions of iOS and at least 4 iPhones (8, SE, SE 2020, 13). I gotta ask my kid if Spotify has such issues, though one thing I treasure with Apple is I can upload my own rare recordings and stream while running or driving anywhere in the world. Not sure that is possible with Spotify?

 

[Head_Unit]

I want to repurpose my old Pixel 4a as a music streamer for it

Sure-you mean fixed/static? i.e. a wired connection? USB stuff typically does not have much voltage output. Can you get digital out from the Pixel into a standalone DAC? Though personally I totally treasure AirPlay's ability to stream whatever on iPhone or iPad from wherever I am sitting or walking around. At one house I use an old AirPort express which measures well (not excellent but probably transparent to most ears). Here I have an AVR with AirPlay. No high resolution though. Not sure what standalone DAC would have AirPlay, Spotify Connect, etc.

 

[staticV3]

Explain more please? That might explain a few things where I couldn't get much volume

See here. Only an issue on Android (and Linux perhaps).