Q&A - Techy Stuff...Raspberry Pi, Linux, etc.



How to change the Micro SD card

Since Spring 2017 B2s have an micro SD card that is not accesible without opening the box. If you want to change the SD card to increase storage for instance. Uncrew the two screws at the back marked with chevrons.

Then pull the rear panel and attached assembly out slowly about 3cm or 1.5 inches.

You may need to prise the panel out with a screwdriver - thats normal. Take care not to damage the metalwork.

I wrapped tape around the screwdriver to protect the metal.

You can just see the micro SD card and it will pop out when pressed.

Reverse the steps to assemble - again its common for the rear panel to "snap" back into place.


Ehernet can give you a more reliable faster network connection. Flat Ethernet cable is less of a squeeze. Open the B2 as above and then arrange the cable like this.

If you need to remove the ethernet cable - you will need a bit of dexterity with a small flat screwdriver to lever up the Ethernet retaining clip. Don't force it. Don't rush. It will come out.


Use B2 as a hard disk

Q: "Hi,We love having our Brennan and leaving it on random play means we look at each other quite often and ask 'who is this?' as it works through our 800+ CDs.
I have just built a Rasberry Pi2 with Pi MusicBox to stream other networked files, Spotify and the like around the house. Is it possible to add the Brennan hard drive as a mount to stream our CD collection too, or could you point in a direction to research this?
Thanks, Ken and Jane"

Hi Ken and Jane. I imagine it is possible but I'm not a suffiicent Linux or Pi expert to direct you but I do want to encourage you. If any readers have some pointers leave a message here and I'll be happy to post. As a starting point you can login to the B2 using a program like Putty User Root Password Brennan.

Bluetooth Out

"I (and I expect many others) already use a wireless music system. I have a Bose Soundtouch system and I would like to add the capability of mass storage of CDs so that I can Bluetooth from it to any of the Soundtouch devices. Unfortunately B2 only has Bluetooth input (rather than out to another device). Are you likely to implement Bluetooth out or would it be possible for me to modify the B2 to do it? I have software experience. Is the software written in Python?

Update - Bluetooth Out is deprecated - its in the software but we are no longer advertising it.

What Amplifier

Q: What is the output of your B2 power amplifier into 4 ohms and if the amplifier is a class T or D, is there a difference in the frequency response into these differing loads?

We use a TPA3110 power amplifier IC please refer to the TI data sheets for detailed technical information.

What make of HDD

Q: I ordered a 2Tb. What kind of internal HDD do you use? what make?

We currently use a Samsung 2Tb - because they are the only folk who do a 2Tb slim enough - 7mm - to fit in the B2 case.


Hi Martin,
I hope you're well. My in-laws are looking for an audio controller and have been recommended the b2 so I wanted to gather a little more info if I may. Firstly, great looking product, excellent to see the rPi being used for consumer grade devices and I love the fact it appears to be a ""maker-friendly"" so I was wondering if there's a public web API for controlling the unit.
I'm a Creative technologist with experience of both the pi and android dev and always looking to tinker so I would be interested in allowing them full control via a custom android app. If there is no api do you provide images of the sd or a github repo with details of the webserver contents?
Thanks in advance for any guidance you can offer and I look forward to hearing from you.
Many thanks, Rich

Hi Rich - sorry there isn't a repo with the API - what I would suggest is take a look at /var/www/index.html on the raspberry pi. That contains all the Javascript that talks to the the B2. Its not beautiful but not very complicated either. If you want you don't even have to login to the Pi - just use the Developer Tools on the Chrome Browser and you can see the code. If you do what the Javascript does (http GET requests for the most part) then you can control the B2. Martin

What Editor?

What Windows text editor should I use to edit a B2 playlist? Notepad displays it on one line without showing any CR/LF or paragraph marks: Word shows the lines and line end markers, but I have not found out how to save the edited file to preserve the original formatting breaks. Thanks Colin

Hi Colin. I use Notepad++ for all my work - can't say I've actually imported a playlist back into B2 though. Martin

Can I add DLNA?


I now have my b2 which is doing exactly what I wanted, and so far many cds have been loaded. My question is:

given that I have understanding of pi and of linux (I have used suse and ubuntu for over ten years), would I be able to install minidlna? Minidlna is a media server that would make music available to any device such as a phone or an Airstream receiver (and thus any hifi setup). It would need access to the library and to be accessed by client devices. But I can't think of a reason why it would not work. If it did, then I would have a dlna server so that everything installed on the b2 could be listened to in any room on any device. That would be special.

I have read that the b2 'isn't compatible' with dlna. But I can't see any reason why that might be. It could become a powerful selling point."

Hello - You are right there is no reason that the Pi cannot run DLNA. What I should have made clear is that my B2 app doesn't. I'm happy to help you with your endeavour. I can point you at the Github repo for the recipe to build the SD card - less the B2 app itself. You could probably add DLNA there pretty simply. Martin

Ethernet Connector

Hi Martin, why it is not possible to connect an Ethernet cable without having to open the Brennan B2? You even describe the problem with the words: ""It is pretty fiddly!""
Would your loyal customers do not deserve an external connection possibility ?!

Hi Wolfgang - Are you the Wolfgang from 2008? Nice to hear from you again. The answer is that I would have to make the B2 box bigger to add any other connector, switch or button. Making B2 as small as possible was the overriding design goal. I wasn't going to support ethernet at all but I realised all I had to do was leave some slots and it was possible even if not beautiful. Martin

Linux upgrade and SD backups

I have created a backup of the B2 SD card and written it to a new SD card as a test. Works well. I have two questions related to backing up the complete OS.

First, is it necessary to create more than one backup image? I'm interested in knowing if I create a backup when the B2 software component is at October 2015, will I be able to update it to the most recent version, or are there any changes that are cumulative and would require multiple updates to get to the current level if the backup had to be used?

Second is updating the underlying Linux OS. Is there any provision for updating the base OS? Linux is a long way from static and there will almost certainly be a number of updates to the OS. Is it safe to use apt-get update to bring the OS to the current level?

Aaagh - Paul what did I say about one question at a time. Only joking but it does make it easier to write the headline when its one question..

You should be OK with your old SD card backup. The web upgrades take any version of code to the current version.

We created a custom linux for B2 and I don't forsee any immediate need to change it. We use a custom linux so that it boots quickly mainly. B2 is a few seconds. Raspberry Pi was over a minute the last time I played with it. apt-get is not included in our distribution. If we did want to upgrade the OS I'd probably make it part of a regular web upgrade so really invisible to most owners.

Batch Delete MP3s

Is it possible to batch delete MP3 files?
I have over 200 podcasts stored on my Brennan,of which I have listened to over 100.
Obviously single MP3 deletion will be very slow!
Thanks in anticipation,

Hi Clive only possible as a Linux user. You need to login to B2 using SSH user root password brennan. You will find the music files at /media/hdd1/music. Delete what you don't want then run Settings->Scan Disk from the front panel to let B2 know what you have done.

If the above is gobbledygook then you probably should not attempt this. Martin

Backup Using NAS

Hi Martin,
I'm thinking of buying a B2 and I'd like to use my existing NAS as a backup.
Based on my understanding of the new B2 NAS feature it will allow the B2 to be visible as a NAS device. This should enable PC based backup software to copy B2 files to my NAS. Is this a reasonable assumption?
PC driven backup would be good. What would be ideal is that the B2 automatically pushes backups to my NAS device. Am I expecting to much?
Best Regards

Hi Mike
Yes you can use your Windows software to backup the B2 - as I say elsewhere the B2 appears like any other folder to the PC.
Backup to NAS from B2 is unlikely in the near future. Never keen on providing multiple ways of doing the same thing.

New NAS SD Card

(Archived instructions for owners with B2s shipped before November 2016)

The new NAS feature needs a new SD card. A simple Web Upgrade is not enough.

B2s shipped after 26th November 2016 already have the latest SD card.

Owners of B2s shipped before then can buy a new SD card from us or create their own as follows.

You need a new or spare 8G SD card (anything larger than 4G will be OK) and a USB SD card reader. You might want to label or mark the new SD card as “new”.

Plug the new SD card into the reader and plug that into USB C on the B2.

Get the latest software on the B2

Settings->Web Upgrade

Download the new operating system with NAS

Settings->Maintenance->Get RootFS

(25 seconds)

Copy the current SD card to the new one.

Settings->Maintenance->SD to USB C

(2 minutes 30 seconds)

Upgrade the Operating system on the new SD

Settings->Maintenance->RootFS to C

(2 minutes)

Turn off the B2 and replace the old SD card in the side of the B2 with the newly created one.

You will need to set up the Wifi again.

Settings->Setup Wifi

You may wonder why I have provided instructions for creating a second SD card rather than simply upgrading the SD card in the B2. The answer is that there is always a small risk that the upgrade fails and that would leave you without a working SD.

Turn on NAS

Settings->Maintenance->Start NAS 


Update 3rd January

James C encountered some difficulties creating an SD card but worked when he added these steps.

1) Before anything format the SD card Settings->Maintenance-Format USB C
2) Before the RootFS to C step - remove and replace the SD card adaptor from USB C (not just the SD card - the card reader).


Aux In Attenuator


Hello Martin,
Having ripped all of my CDs onto the B2, I have started to think about transferring my cassette tapes.
I played a tape through my Denon DN-790R deck and listened to the sound through the B2. It was clearly very distorted.
The software on the B2 is 27th. Jan 17.
Some years ago I made a 20dB passive attenuator to use with the Denon, so I put this in the signal path.
This time the sound was not distorted but far too faint even when the B2's volume control was at 64.

The Denon output spec is 775mV (0dBm) with a 47k ohms load.
Could you tell me please the impedance and sensitivity of the Aux In circuit on the B2? (or what chip you are using if that is simpler). I can then construct a suitable attenuator unless you have another suggestion perhaps.

Thanks for your help,

Hi Adrian - here is a snippet of the Aux In circuit. Your 20db attenuator is obviously a bit too drastic. You just need a pair of resistors in each of left and right or a dual gang potentiometer. The right answer will depend on your electronics skills and what you have to hand. Martin


SD Card Image

You can create our own SD card if you have a PC or Mac.
Install a copy of Etcher
Then download the image file from here
Plug your target SD card into your PC (you can use a USB SD card adaptor)
Then fire up Etcher and point it at the image file you downloaded. Select the SD card and click on Flash.
Once installed in the B2 you will probably want to do a Web Upgrade to get the latest code.
Any SD above 8G will be OK. Class 10 will boot faster but otherwise not important.

Upgrade with spare drive.

Can I upgrade the hard drive as I have a spare 128Gb SATA ssd and a 160Gb IDE?

Hi - I assume you have an SD only B2. Sorry your B2 has no SATA electronics or hard disk mounting hardware so you can't simply open it up and plug in a drive. If you had a 500G B2 say then no problem about opening it up and swapping a bigger drive. You need to do Settings->Maintenance->Format HDD after if its not FAT32. Martin

Extend storage with USB drive

Can I use a USB ext drive to supplement the 64Gb model?

Sorry no. The JB7 could do this but B2 does not. Martin

Change Hard Disk Drive

B2 owner Brad in Ontario has written these very clear instructions how to install a bigger hard disk.