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Finally I've got it working with the smallest amount of crackle and hiss. Yes it stayed in the drawer for that long.
I've gone down from Raspberry Pi 3+ with OSMC to a Pi 1 B+ with Volumio.
The sound after the GPIO13low, could be the cause of the 13 :), is brilliant.
I don't have another tube for now, but the one supplied is very sensible, it picks up noises very easy.
I've got 2 questions:
1. The temperature of the heatsink should be that high? I know that someone else asked and you've replied that is ok at 70 degrees (Celsius?!). My board connector is warm to touch (more than 38 Celsius. The rest of the components are hot. The 2 big capacitors almost as hot as the heatsink. Can I change the heatsink with a bigger one? I don't want a fan, and for sure I don't like that temperature.
2. It is possible/feasible to build a "Faraday cage" around the amp? To eliminate the hum from the surrounding devices. If not there are not so sensible tubes? Now I'm running with the music form SD card, but I would really like to have access to the NAS via WIFI.
Finally got around to building up my tube amp HAT onto a Pi2. I think I've got it all in the right places, but I've seen pictures that show it with a nice looking volume knob. I didn't get one in my pack - is that right?
Yeah I figured. I ended up setting up the thing differently anyway. It's less of a problem now :-)
Thanks for the quick answer!
The only real issue (aside from wasting power) id the life of the tube. The tubes are very conservatively rated at just 2,000 hours, though you should get 2-3 times that in most cases. And they degrade as opposed to not working after time. Note that even 6,000 hours is only about 8 months.
I was wondering. How good or bad of an idea is it to leave the tube powered on 24/7?
It does not have to be exact. Really anywhere from 13V to 14V works very nicely. At the high end of 14V you have about 8V margin so you can get 16V p-p or about 5.6Vrms. More than enough to drive high impedance headphones.
Thanks for pointing it out. It took a bit of time to make it precisely to 13.4V as the screws are very sensitive. Once done, the 503HTA sounds phenomenal again. Good stuff!
The HW reference manual,
shows the location and pinout of the bias header. In general we bias each channel for 6DJ8's to about 13.4V. Higher gives a bit better THD results, but you lose headroom.
Someone might have mentioned it before. Just wondered if there are instructions to re-bias new tubes? I understand the two plastic screws is to do just that. But, would appreciate some pointers where to take the voltage measurements. Thanks in advance!
Is there a good case which still lets me add the header on top of the pi?
Thanks for the help, I have got it working. It was much easier than I expected. Once I realized I had to enable SSH to get puTTy working and after I found out how to edit files of the operating system it was so easy. Just putting the needed device line in the config.sys of the flash directory was enough. Kodi immediately showed a new device in the audio setup.
My new wish is to find an easy way to switch from HDMI to headphone. Anyway so far so good and thanks again for the effort. BTW I strictly use the libreelec .tar files to update so I see no need to use Noobs (anymore).
The file of it will be a hidden partition at the noobs or multi boot.
Therefore, using Win32 Disk Imager., it copies an img file to SD.
3.1 Installing using Windows
Copy a 'LibreELEC-RPi2.arm-7.0.2.img.gz' file this.
Since it is a partition which can be seen from Windows, you can edit config.txt.
If you can use SSH,
A set of DAC is set up by Device Tree Overlays.
@Tasuku Thank you for trying to help me. My Libreelec does not seem to have a boot directory ( or it is hiddden). I only found a config.txt file in the flash directory and that one seems to be involved with memory. Any other ideas anyone? BTW: I am using the latest versions of Librelec by copying the tar file in the update directory. This means I am also looking for a way that I don't have to update any files everytime I have installed a new version of Kodi.
I am using LibreELEC/Kodi of Raspberry Pi3 and 503HTA.
The LibreELEC is stable from Volumio2.
A set follows the document of "503HTA Player Setup Guide."
The file /boot/config.txt must be edited.
Reboot and start LibreELEC.
Audio Output Device ALSA:Default(snd_rpi_hifiverry_dac Analog)
It is better not to use NOOBS by Windows, when LibreELEC is installed in SD.
Because, it is difficult to edit /boot/config.txt by Windows.
It installs a system image.
It can perform edit of /boot/config.txt in Windows after an installation.
Also FWIW the original issue that I thought might have been overheating appears to have gone away. I'm using Volumio and selected the 503HTA as the output instead of Hifiberry - not sure what the impact of that might have been. It still makes some fairly awful noises if I get my phone too close too the unit but otherwise all good.
@rwengland I have had the same experience. I disabled the onboard wifi and attached a USB extension to my Pi 3 and the clicking goes away.
I am afraid we have not spent any time on Kodi or OSMC, as our primary goals were the various audio only players, not video.
Anyone out there that can help Fred?
@Pi 2 design
Have you been able to do some testing to get the Amp to work with Kodi/Libre elec? So far I am using the Amp strictly as a switch to turn on my Pi. A most expensive switch! I have not been able to find an easy way to enable the Amp. I am using the Pi as a media server and don't have a keyboard attached and I didn't get putty to work on my PC to make the changes in the startup. Currently I simply update Libre/Kodi by putting the new .tar in the update folder which is a fast and easy way to update. I am also not keen on editing Libre/Kodi each time after an update. I hope you can find a solution for this.
Clicking Fixed! I suspected (and with your help have now confirmed) that my OurLink WiFi stick was the source of the clicking. The WiFi stick was plugged into one of the four USB Ports on my RPi. I unplugged the stick; plugged in a USB extension cord and then replugged in the USB stick. If the USB stick is moved close to the RPi/503HTA you can hear very audible clicking. Move the USB WiFi stick away from the RPi and voila the clicking is gone. Thanks very much John and Pi 2 Design for the help!
Then I would suspect wifi. Can you send a picture of your setup to email@example.com.
My power sources for the DAC and RPi are separated following Update #36. I don't hear any cracks on music files from my NAS. The cracking noise only when I stream through the combination of AirPlay and 503HTA.
Guys - in both cases you will need to bend the Pi power pins to isolate the Pi 5V rail. This was described in Update #36 on Sep 26 2016, titled "PI 3, Pi 2 and noise". This should rid the system of the clicks and pops.
My 503HTA (on Runeaudio with a NAS source) with a linear power supply unit independent from the RPi sounds great. The microphonic issue when touching the volume dial got resolved by the 3D printed knob.
Here is the problem ... when playing music from my iPad or Spotify via AirPlay, there are frequent cracks. My other RPi (with Runeaudio) with external DAC does not have this issue. Just wondered if any other backers experience similar issues.
I'm running Volumio and my pi is connected to my network wirelessly via an Ourlink USB stick plugged into a USB port on the Pi. I have a *very* audible clicking noise (~500 to 1khz?) that ceases if I touch the volume pot on the 503HTA -or- the plastic case of the Ourlink USB wifi card. The clicking persists at fixed, audible level at any volume setting. If I increase the volume to annoyingly loud music levels, i can drown out the clicking, but this highly annoying and defeats the purpose of having the 503HTA and Pi dedicated to playing music. Can someone suggest or help me address this problem please?
Fred - You should be able to follow the instructions for Kodi and select a Hifiberry DAC (not DAC+).
Has anyone else tried this? We will take a shot at this here.
Do you get the same problem with a pair of headphones? Please send a request to firstname.lastname@example.org so we can log the issue and work on a fix or replacement as appropriate.
I have set up my amp via the instructions connected to a RPi 3, with pins bent as suggested and it works great for maybe half an hour and then it appears to overheat and makes horrible noises through the speaker. I'm using it plugged via headphone jack into the input jack of an old Bose iPod dock. The heatsink gets very hot quite quickly and I'm wondering if I've got some issue with my set up or if it's the amp. A little help would be appreciated - I've gone back to my old original RPi minus the amp.
I intended to use my Tube Amp for Kodi/Librelec/Pi2. Should I be able to get this to work?
The Amp works great stand alone with analogue input. But does not do anything on my Pi2. May make sence since I cannot install the right output with audio settings of Kodi.Does Librelec /Kodi need specific support to be able to do this?
Javier - Can you send us a picture of your setup to email@example.com? Are you using a Pi 2 or Pi 3?
Very disappointed in this. I get so many cracks and pops during playback it's frustrating, and I don't understand why. I tried new and old cables. I disabled wifi. I pushed the serial pins that control power flow off (as mentioned in an update). Still get the same random pops and clicks. Very frustrating. I don't know what else to do except use the pi for another project and chuck the tube in the trash.
I started to use Volumio and used this installation guide:
" Install and enable the 503HTA Plugin (from accessories category)"
I haven't use any other options just that default plugin setting. This is working.
How about that soldering option in the comments here?
Could that be solution to overcome the noise coming from PI? Anyone have ideas?
I have also tried to find somekind of plugin like this:
Cheaper option would be great! If someone finds one please let us all know. :)
There's a new release of Volumnio that has a plug-in for our hat plus a separate DAC setting for it as well.
Has anyone tried this new version? Are you using the new options? If so, how is it working & what settings are working best for you?
Problem solved, I contacted Pi2Design directly and got an invoice within 5 minutes. Great support :D
Does anyone know how I can get a proper invoice for my order? I live in Germany and I need to pick up the package at customs and it could be that the want to see a real invoice and I think the confirmation mail from Kickstarter won't be sufficient. Thanks.
I started getting some pi 3 noise coming through again (which seemed to mostly go away when I swapped tubes). This time I found that disabling wi-fi on the pi 3 stopped the noise (I run via ethernet).
Yes, Roon takes care of that. I am listening to Tidal all the time on the pi (through Roon). The pi in this case is just the music streamer, not the server. You run Roon Bridge on the pi, and Roon server on some other machine on your local network. I have several pi's streaming music this way, but I am really loving this hybrid tube amp/dac combo.
Roger, thank you, I'm just going to look at Roon. Presumably, someone (not me) would have to gain access to Tidal's source code to get it onto the Pi?
I meant to say, you have to run the Roon server software on some PC (Mac, linux, etc.) other than the pi.
Regarding Tidal, if you use Roon software the Tidal integration is superb, and I am running Tidal through mine. Roon costs $120/year unfortunately but in my opinion well worth it, not just for Tidal but for all the other features and capabilities (and that cost is for the whole network, if you have multiple streamers/pcs etc.). You do have to use a Roon server (other than the pi) to run the Roon server, and then run the Roon bridge software on your pi.
Hi. Have been trying various Pi (A+, B+, 2B, 3B) with Ethernet and various wifi dongles running Volumio 1.55 (this seems a bit more stable still than 2.00). The lowest background noise seems to be with a B+ and this wifi dongle from eBay http://www.ebay.co.uk/itm/281695871868…
The noise with this is even a bit lower then using Ethernet, which seems to pick up some very low level hum. The amp does seem very susceptible to picking up RF interference, but when used well away from any call phones and other devices it really is very good. I do get a very occasionally shortly buzz but only in the left ear speaker when the Pi seems to be accessing the network. If anyone knows how to get rid of would be great. But apart from that I am delighted with the amp and it's warm sound, currently through Bose 15 headphones. Hope this helps users with ideas to try out different Pi and wifi combinations to get the best listening experience. Thanks for a great Kickstarter.
Hi everyone, very excited here as I put my tube amp together. Just wondered if anyone has any thoughts about enabling Tidal on the Pi to play through to the tube amp
Thanks, that makes sense. I knew about the jumper but wasn't sure what I would need it for. I'll try the other tubes again and compare. The amp sounds great now! I am very happy with it. I had Roon playing through it all night to burn in. I'll post something over on the Roon forums about it as I know a number of Roon users are interested.
Thanks for that info. We had only been vaguely aware of other tubes having more or less sensitivity to RF. We know about microphonics, which is a more physical phenomena.
As for the 12AU7, you need to move the 6V/12V jumper to the 12V position. It is located on the upper right near the line in jack. See here:
I solved the problem with the noise. I tried moving the pi to a different location, plugging into different outlets. I tried with a different power supply (to the pi 3). It became clear that noise on the pi 3 bus was clearly coming through--I could hear the equivalent of disk activity (flash card or network access) which would coincide with the activity of the pi. (This was even with pins 2 and 4 bent out).
I swapped a different tube (a 6922 I had sitting around) and the noise stopped! I guess the shipped tube was really sensitive--picking up this low level RFI. For some reason another tube is less sensitive. I am learning more about tubes all the time.
I tried using a 12AU7 tube (I tried two different ones) and in both cases I only got a right channel coming out. The manual says it supports 12AU7 tubes. I don't understand this. Bad tubes? I am not sure if I need to adjust bias since I swapped the tube.
Other things I will try to diagnose: plugging in at a different location (maybe some external noise finding its way through?), try it with a different pi 3 (I have several, but not eager to bend pins on the other ones).
I received my amp yesterday, and assembled it with my pi 3. I bent out pins 2,4 exactly as the photo shows. I also added the script to bring down gpio 13. I installed Roon bridge software. Everything worked the first time, and I was playing Roon through it in very short time. That's awesome!
However, there is some serious noise coming in apparently related to the pi, even though I have bent out the 2 pins. I hear 1-2 seconds of a mechanical, static type sound, very loudly, about every 10 seconds. It is rhythmic, in that it follows a pattern, so not related to bad connections or anything. I have tried connecting the pi via ethernet, and via wi-fi, and both work yet both have the sound problem. So I don't think it's related to either (although I didn't ever completely disable wi-fi). If I power down the pi the noise goes away and the amp is quiet (other than the very low noise I expect from a tube amp). So I would say the only issue is that rhythmic noise issue, but it will certainly prevent me using it with the pi if I can't resolve it.
Has anybody experienced noise problems with a pi 3, with pins 2,4 disabled?
Moving the WiFi adapter away with an extension cable certainly made a difference, so thanks for the suggestion.
The problem with an audio frequency filter for the 5 V rail is the size. In order to be effective the inductor we would have to use would be hundreds of microhenries. An inductor of that size would be as large as the headphone connector, perhaps even a bit larger in order to carry 3 to 4 A it would require. Then there would have to be an equally large capacitor to form the filter.
Have you tried placing the Wi-Fi dongle on an extension cable to move it away from the board?
I've had my amp for a few days now and I'm enjoying listening to it a great deal indeed.
@Pi2Design, what would a suitable filter circuit look like? Can you post a circuit diagram? As Gregory Roberts says, it would take some soldering, but a circuit design would be useful for those willing to try.
I'm using a Pi2 and 32ohm Beyerdynamic headphones at the moment. With no WiFi dongle and a wired ethernet connection, the noise is acceptable - just a few soft clicks audible when no music is playing. But when I use an Edimax WiFi dongle or a Pi3 with WiFi the noise can be heard in quieter sections of music.
No I did try your workaround to bend the pins as proposed. Many reasons to this. First and foremost, I don’t want a dual power supply. It's a kind of killing point regarding convenience (we all got our special ideas I guess). Second, as I would really not ruin a good and healthy Pi3, I am waiting for the feedbacks on Pi1…