Raspberry Pi Tube HAT - Pi 2 Design

Audio Gear Talk Raspberry Pi
41

Remember my answer? All my Pi’s run that way. :slight_smile:

Anyway – things have stabilised nicely since my previous post, and I’m glad I can report the little tube amp runs fine in stand-alone mode. No noise, just a warm, full-bodied sound. I’ll keep it as it is for now, since my PiDAC+ is a better DAC compared to the PCM5102A that Pi2Design used for the Tube HAT and it gives me the opportunity to finetune the channel balance through amixer, so the stereo image is not skewed to my hearing (my left ear is better than my right – and the PCM5102A does not have mixer controls).

It also gives me the opportunity to swap around a few different DAC HATs – which could run out of hand quickly, I’m afraid.

In short: I’m quite happy. As far as Kickstarters go, this was a nice little journey. Interested in your finding, @andybob!

42

The rolloff can be eliminated by pulling GPIO13 low in software. As each player and environment is different there is not one way to do this. We will have a simple script and some instructions for various environments asap. We just need to do more testing. There will be a campaign update as soon as that is ready.

As for the Pi 3, we had good results when we powered it separately (bending the two 5V pins out of the way) and shut off the on-board WiFi and Bluetooth.

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43

Pleased to hear you’ve got it working satisfactorily Rene.

I put it together with bent pins 2 and 4, powered up Pi and HAT separately and tried to use the latest HiFiBerry Roon image (configuring WiFi in wpa_supplicant in the visible FAT). The Pi booted but couldn’t get WiFi working (probably both because I was using spaces in the SSID instead of _ and enclosed the psk in quotes). I attached an Ethernet cable and the Pi showed up in the wired network, but not as a network zone in Roon.

Any suggestions welcome !

44

but it didn’t work here :stuck_out_tongue:

45

Even though the Tube HAT uses the same chipset & driver as the HifiBerry DAC (non-plus), the Hifiberry Roon image is meant to be used with ‘genuine’ Hifiberry boards – I’d guess some form of identification is part of the certified RoonReady process.

Guess it’s time to roll your own. My Tube HAT worked fine with DietPi / Roon Bridge.

OT: Got a Hifiberry DAC+ PRO with dual oscillators coming in tomorrow – will be fun comparing it to IQAudio’s PiDAC+. :slight_smile:

1 Like
46

Running the Hifiberry DAC+ Pro to the little Tube amp now. Nothing conclusive compared to the IQAudio PiDAC+ as of yet – other than that the combo sounds really sweet.

I’ll try mounting a Pi to the Tube DAC once the roll off solution arrives, just to check it out, but I think this will be a great setup for the foreseeable future.

Then again – if I close my eyes, I hear the faint call of a Mamboberry in the distance… :wink:

47

Was able to pick mine up today.

Sounds great on my Pluto’s. The winning recipe:

  • seperate power on the pi
  • roon bridge on Jessie

I’ve also tried hqplayer and having the pi powered by the hat, in all permutations, but no winners among them.

Happy the way it runs now. Another kickstarter donation that paid off.

Might get around switching to Dietpi at some point, but if it works… :slight_smile:

48

Listening to Beck’s “Morning Phase” 96/24 through the Tube HAT. Getting a healthy volume into my Nokia BH-905. They’re 32 ohm so I’m using the centre position for the output impedance.

Installed DietPi. I like to do that initially with screen, keyboard and mouse on the Pi so I can tell when the setup has finished and it’s ready for an SSH login. Then I take the peripherals off and use a terminal from the PC over Ethernet. Alsa and ffmpeg software selected and installed, Turn on the HAT and select HiFiBerry Dac as sound card. Roon Bridge installed. Pi shows up as a zone in Roon, changing to DoP enables up to 192 kHz and DSD64.

I think I like the idea of separately powering the Pi and the HAT, means I don’t have to get fussed about turning off the amp with the volume switch, I can just leave the power on for the Pi.

Poor little thing is noise sensitive. I’ve got it on the desk atm being powered from a USB hub and there is intermittent noise from the PC. and a hi frequency low volume “hash” when nothing is playing. Hopefully it will do better in the bedroom isolated away from the PC.

But to get it into the bedroom I have to get the WiFi working and Dietpi-Config isn’t seeing any WiFi hardware even though a USB dongle is plugged in. The dongle shows up fine on my PC. lsusb shows a Realtek Semiconductor Corp. device which isn’t there when I pull the dongle, so thats what it is. I’ve tried

apt-get install firmware-realtek

but it tells me that its up to date.

lsmod says:

Module Size Used by
cfg80211 427855 0
rfkill 16037 1 cfg80211
snd_soc_hifiberry_dac 2511 1
bcm2835_gpiomem 3040 0
snd_soc_bcm2835_i2s 6354 2
bcm2835_wdt 3225 0
snd_soc_pcm5102a 1763 1
snd_soc_core 125885 3 snd_soc_bcm2835_i2s,snd_soc_hifiberry_dac,snd_soc_pcm5102a
snd_pcm_dmaengine 3391 1 snd_soc_core
snd_pcm 75762 4 snd_soc_core,snd_soc_hifiberry_dac,snd_pcm_dmaengine
snd_timer 19288 1 snd_pcm
snd 51908 4 snd_soc_core,snd_timer,snd_pcm
uio_pdrv_genirq 3164 0
uio 8000 1 uio_pdrv_genirq
fuse 83653 1
ipv6 347466 20

Those first two processes look like something to do with the WiFI dongle, but I’m not sure what it means. Anyone got any ideas ? There may be a driver that I have to download.

Looking forward to a script and instructions so that 44.1 kHz can work properly.

49

I’ve powered the Pi3 seperately and don’t seem to have a high tone.

Which makes sense according to their kickstarter notes:

A proposed solution is to remove (or bend out of the way) the two pins
from the Pi GPIO header that is used to feed 5V to the Pi. This would
then require the Pi to be powered via it’s micro-USB power connector as
usual. The good news is that doing this removes the noise completely,
including the Pi 3 tone.

Although their following notes on the topic don’t repeat this.

So, if you power the pi separately, you should not have to worry about fixing the high note on 44.1 kHz.

50

The 44.1kHz issue is a severe roll-off in high frequencies, created by a misconfiguration of the DAC chip – not a noise issue. Try playing a highres file and a 44.1kHz file back-to-back – all treble is gone on the latter.

@andybob: any specifics about the dongle? Type/chipset #s?

51

2 posts were split to a new topic: Realtek RTL8192EU ID 0BDA:818B WiFi drivers for Raspbian

53

Ah, understand the issue now. It is an across the board rolloff of high.

Easy to fix with a simple script (and then test the sound difference).

Create a file called ‘gpio13low.py’ (sudo nano gpio13low.py) with the following code:

import RPi.GPIO as GPIO
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(13, GPIO.OUT)
GPIO.output(13, GPIO.LOW)

You can run it using:
sudo python ./gpio13low.py

If you want to see what the state is, you could create the following file (sudo nano checkgpio.py) which shows 0 or 1 depending on low or high state.

import RPi.GPIO as GPIO
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(13, GPIO.OUT)
print GPIO.input(13)

And run it using sudo python ./checkgpio.py

And of course you can create a second file to make it high again (GPIO.output(13, GPIO.HIGH). That allows you to easily toggle and hear the difference.

If you’re lazy and don’t want to manually run the sript each time you start your PI, you just add it to startup:
sudo nano /etc/rc.local

In this file, before ‘exit 0’ add in the following line:

sudo python /home/pi/gpio13low.py &

As you can see, I stored the .py file in my home directory (as user pi), if you store it elsewhere, make sure to refer to the file.
After you;ve done this and rebooted your PI, run the checkgpio.py script to ensure state is indeed 0 (sudo python checkgpio.py)

I’m sure this can be done more elegantly, but it works for me :slight_smile:

2 Likes
54

Thanks a bunch! It has a poetry-like elegance to it… :wink:

1 Like
55

Thanks @rovinggecko,

I get an error from both scripts:

ImportError: No module named RPi.GPIO

Is there a GPIO module I need to load into Dietpi ?

Edit: Found it thanks:

apt-get install python-rpi.gpio

All working and thanks very much for your script :grinning:

56

Great! I guess Debian Jessie Lite has it included and Dietpi doesn’t.

How’s the sound now?
I’m actually pretty happy. I also think that the tube adds something when listening in the evening hours :slight_smile:

57

I’m pretty happy as well – spent most of last night listening. The little tube performs admirably.

I’ll keep the Pi separate – it gives me the opportunity to fiddle with other DACs and alsamixer/amixer/crossfeed.

I like the Hifiberry DAC+ Pro a lot – don’t know if it is the dual clocks, the Tube, the crossfeed or the combination of the three. Should really learn to make one change at a time. :wink:

58

One change at a time = structure = work
Relaxing = let you mind flow = changing what feels like changing

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59

WiFi working (thanks Rene !)
44.1kHz sounding good (thanks rovinggecko !).

Lying in bed listening to the new Pixies - Head Carrier. There’s some electronic crackle/squirt noise I can hear in quiet passages or between songs. I fear it might be WiFi related. I’ll try and track it down and see if anything can be done. Maybe getting the aerial further away from the tube.

Swapped in my Mullard 6DJ8, still breaking in; but a bit richer than the JJ.

Amazing to think of how the music is coming from Tidal/Roon/WiFi/Pi HAT.

Mark me down as pretty happy too.

Edit: Shifting the WiFi aerial has dropped the noise considerably. There will be an optimum configuration. Much less general noise in the bedroom than when hooked up to the PC.

60

OK you two (and anyone else) are officially challenged to a Most Beautiful Knob competition.

Bonus points for Bakelite.

61

Had to read that twice and still choked on my tea… :smiley:

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