Simple mod for RaspberryPi and HifiBerry DAC / Digi - plus various others ;-)

sondale

Some people may have seen this mod elsewhere but it is something I only spotted this morning.

It involves feeding 5 volts into the HifiBerry DAC or Digi which then powers the RPi - so DO NOT CONNECT USING THE MINI USB SOCKET.

The reason for doing this is to bypass the switching circuits on the RPi, this means that the 5 volts should come from a linear power supply not another switcher.

The mod is completely reversable, which is nice!

I have done this on RPi 2B and a HifiBerry DIGI+ (and I will try it on the DAC+ Pro), I am not sure about earlier models having this facility.

On the HifiBerry DAC+ and DIGI+ there is a connector marked P3 which sometimes is also marked [- 5V +]. The first thing to do is to solder into this position a two pronged connector (vertical or horizontal) with 2.5mm spacing. Now a means of connecting an external 5 volt supply is needed.

I decided to use a connector cut into the side of the case which I soldered to the pins, needless to say if you get the connections round the wrong IT IS GOODBYE TO THE DAC/DIGI AND THE RPI - so please be careful. I then connected my John Swenson design 5volt psu, the result - impressed, very impressed.

I will take some photos of the RPi and DIGI boards tomorrow and post them. It is Saturday evening and it is time to relax, read a book and listen to some music. 

uglymusic

Interesting Alan

Looking forward to the pix.

sondale

The first photo shows the 2-pin header with the wires connected (soldering is just about OK).

The second shows the DC connector (I am using a 5.5mm / 2.5mm plug & socket), below you can see a Momentary switch which I use to reset the Pi. There are a couple of holes for a 2-pin header on the Raspberry Pi marked P6 on some boards and Run on others, just solder a 2.5 mm spacing 2-pin header in this position and connect a momentary switch across them.

This does not do anything for the sound but it does make life simpler when things go wrong on the Pi, much better than pulling the power cable out and re-inserting.

shoom

Interesting Post

I have a Digi + pro board on order and am planning on using it as an I2S transport so this info will be useful.

The momentary push switch will also be useful as it allows a reboot without opening the case.

I’ve not got to build a Linear PSU yet but that’s also going to be on the menu later but the IFI Ipower that I have ATM is way better than the standard PI PSU to my ears.

Looks fairly straight forward and bypassing some of the PI’s PSU arrangements can only be a good thing IMHO.

Any thoughts on the SQ?

sondale

I also have the iFiPower unit for 5volts and agree it is very good, I will try it in this configuration I just need to convert its DC plug. As to the sound, the changes are difficult to describe; on Orchestral works instruments are easier to locate, they have more body. Listening to Ravel's String Quartet was a bit of a revelation especially hearing the way strings are plucked in the second movement. As sckramer on DiyAudio put it "no digititis/hash" - it was his mods at which I was looking.

shoom

Great

Sounds like a winner.

And how does the IFI stack up against your Linear?

Nick (Lurcher) measured some PSU and while his Longdog came out pretty well the IFI also seemed to be much better than the standard PI supply. BTW I have no reason to doubt Nick's honesty and trust his conclusions.

Are any of the adaptors supplied with the IFI 2.5MM (I know that the standard one is 2.1mm)? I've not checked those out much.

But thanks again for a timely post which is helping me to put the pieces in place for the streamer.

sondale

I have not tried the iFi in this setup, but will do in the next few days. The iFi power units come fitted with a 5.5mm / 2.1mm plug, however there are a nice set of adapters supplied one of which is 5.5/2.5, just what I need.

shoom

cool

I'll look forward to your thoughts.

sondale

Looks like I am wrong about being able to the same mods on the HifiBerry Dac+ Pro. If you apply 5 volts to the board via the 2-pin pad then you have to remove a resistor and then ONLY THE ANALOGUE PART OF THE DAC USES THIS 5 VOLTS, NOT THE PI. So the mods only apply to the DIGI+ board.

shoom

Yes I've read that somewhere but TBH I'm only really interested in the I2S part of the board but may take out the 0ohm resistor just to disconnect the analogue part of the board.

I'll also give hacking in to the XO's supply (supplied from the PI board ATM) when I'm in the mood for such things.

Just waiting for the Berry DAC to arrive.

shoom

Interesting

The Hifiberry DAC+Pro turned up today so I thought that I’d hook it up for a listen.

The first issue was Moode not loading the selected drivers for the pro so I thought well just to get her going id load the standard DAC+ drivers and bingo.

Had a listen

Then after a re boot I was able to load the pro drivers and the clocks do seem to make a difference.

I checked in Audio Info and the pro was listed and master mode also.

Sounds pretty good and way above expectations and for £32 quid it’s abit of a bargain.

Compared to the IQAudio t sounds a little tighter wider and more full bodied.(I’d never compare DIY products this way BTW). I found the IQ a little Left and right obvious and stuck inside the speakers a tad. Also a little thinner and lacking bottom end welly but that’s just to my ears/my set up/IMHO.

Small differences but maybe valid.

I2S is looking promising.

I may order another just to have as a stand-alone unit.

Anyone who wants to try don’t forget to set the Alsa mixer for 81 or clipping may follow.

 

cj66

shoom said:

Anyone who wants to try don’t forget to set the Alsa mixer for 81 or clipping may follow.

 

Is that the No. 81 to Malaga? (Alsa is the bus company here)   


All interesting stuff, I'm getting tempted to try...

uglymusic

shoom said:

Interesting

The Hifiberry DAC+Pro turned up today so I thought that I’d hook it up for a listen.

The first issue was Moode not loading the selected drivers for the pro so I thought well just to get her going id load the standard DAC+ drivers and bingo.

Had a listen

Then after a re boot I was able to load the pro drivers and the clocks do seem to make a difference.

I checked in Audio Info and the pro was listed and master mode also.

Sounds pretty good and way above expectations and for £32 quid it’s abit of a bargain.

Compared to the IQAudio t sounds a little tighter wider and more full bodied.(I’d never compare DIY products this way BTW). I found the IQ a little Left and right obvious and stuck inside the speakers a tad. Also a little thinner and lacking bottom end welly but that’s just to my ears/my set up/IMHO.

Small differences but maybe valid.

I2S is looking promising.

I may order another just to have as a stand-alone unit.

Anyone who wants to try don’t forget to set the Alsa mixer for 81 or clipping may follow.

 

Are you telling me I bought the wrong DAC?????

shoom

uglymusic said:

shoom said:

Interesting

The Hifiberry DAC+Pro turned up today so I thought that I’d hook it up for a listen.

The first issue was Moode not loading the selected drivers for the pro so I thought well just to get her going id load the standard DAC+ drivers and bingo.

Had a listen

Then after a re boot I was able to load the pro drivers and the clocks do seem to make a difference.

I checked in Audio Info and the pro was listed and master mode also.

Sounds pretty good and way above expectations and for £32 quid it’s abit of a bargain.

Compared to the IQAudio t sounds a little tighter wider and more full bodied.(I’d never compare DIY products this way BTW). I found the IQ a little Left and right obvious and stuck inside the speakers a tad. Also a little thinner and lacking bottom end welly but that’s just to my ears/my set up/IMHO.

Small differences but maybe valid.

I2S is looking promising.

I may order another just to have as a stand-alone unit.

Anyone who wants to try don’t forget to set the Alsa mixer for 81 or clipping may follow.

 

Are you telling me I bought the wrong DAC?????

nope

Just sound a little different but both good.

The tonal balance preference is going to be a down to ears and systems. To my ears the Berry sounds a little warmer and juicier than the IQ which is odd because I've found the opposite in the past between Sync and Async  DACs.

http://forums.stevehoffman.tv/threads/dacs-difference-between-synchronous-and-asynchronous.273060/

But I do like that hence my fascination with Jfets and earlier tubes.

Not every ones cup of tea.

uglymusic

This may be related - or not.

I've always been on the transistor/digital/cool/analytical side of things. But a friend listening to my system before the RPi came along described the sound as being 'warm'. I still haven't figured that out. I love the sound I'm getting now...

shoom

Yup but your ears come first in your system :-)

Or maybe you are a tube head at heart :-)) after all.

Have a listen to the IQ and let me know what you think as more opinions give a better balance.

I'm using one of these as pre ATM

http://www.amb.org/audio/alpha20/overview.shtml

Just the line-stage not the full thing with a DACT switcher  x3 gain and together with the SECA it’s making nice music.

Maybe influencing the sound in a certain direction.

So I'm interested to hear what you find in your set up.

uglymusic

Of course! But, as you say about the IQ DAC, it's always interesting to hear what others say about the sounds I'm making.

Possibly a tube head, but very unlikely ;-) I've not heard a tube amp that, to my ears and priorities, holds a candle to one of Colin's SECAs (there's fightin' talk).

The pre looks very interesting. Is it single-ended Class A?

sondale

For the adventurous only - you can get a lot more out of the IQAudio DAC+ with a little (not easily reversible) mod - but it involves unsoldering two tiny SMD resistors and replacing with a couple of expensive (£10) resistors. 

This is what people on AOS have done (so have I of course) and it gives very good results.

Having said that I am becoming more and more happy with the RPi 2B/HifiBerryDIGI+/Linear PSU/[Caiman II / iFi iDSD micro] setup.

shoom

uglymusic said:

Of course! But, as you say about the IQ DAC, it's always interesting to hear what others say about the sounds I'm making.

Possibly a tube head, but very unlikely ;-) I've not heard a tube amp that, to my ears and priorities, holds a candle to one of Colin's SECAs (there's fightin' talk).

The pre looks very interesting. Is it single-ended Class A?

The pre is a complimentary pair 2SK170BL/2SJ74BL BJT op stage so not single ended. Reminds me of John Curls work a little but this circuit has been doing the rounds in one guise (JISBOS) or another for some time.

I'd love to build a SECA pre which could be a better match SQ wise but for now it's good enough as is the BA3 as a pre.

It’s really easy to adjust the gain by changing the FB resistors. I have sockets soldered in that spot so just plug and play.

''For the adventurous only - you can get a lot more out of the IQAudio DAC+ with a little (not easily reversible) mod - but it involves unsoldering two tiny SMD resistors and replacing with a couple of expensive (£10) resistors.''

Yes the Charcrofts can be good in the right spot and I'm assuming these are in the OP filter of the IQDAC. 

They can be had here if any ones looking.

http://www.hificollective.co.uk/components/car_resistors.html

uglymusic

I'm starting to feel out of my depth here! :-)

shoom

nooo

it's the terminology that get's a little confusing but really if you see the A20 as a 3 stage push pull pre amp it makes sense.

So the phase goes.

Relative to the input.

1st stage OP -out of phase

2nd stage OP-back in phase

3rd stage is a buffer so the phase does not change.

So the OP is in phase with the IP (Give or take a foot).

The IQaudio and Berry DAC use PCM5122 DAC chip which uses a Negative charge pump arrangement for it's OP. it's a good work around and means that it can use just a positive supply to work (cheaper to implement). The charge pump generates the negative OP rail but that sort of arrangement can need some filtering to remove the HF rubbish generated on the OP,

I generally prefer unfiltered myself.

These sort of chips have come on a long way in a short time.

They are relatively cheap to manufacture and so they arrive in the low rent PI DACs that we have now.

hopeless explanation but may make a little sense.

I built a DAC with the 5122 smaller brother and it sounded pretty good if a little limited detail wise.

For sure these DAC's are a long way from being a mature product but they also have come a long way quickly.

Any mistakes?

Please feel free to correct them if anyone cares to it's fine by me.

I'm just Mr average

uglymusic

Thanks Shaun. I need patience here, and you seem to have it ;-)

It's not just the technicalities, but the soldering and unsoldering - especially of the 'ickle components. I have to take Colin up on his crash course in molten metal and singeing. 

shoom

Soldering and unsoldering.

Well we all have a different take on that.

Colin likes the silver loaded stuff which is OK but needs more heat to melt which is not so good IMHO. And should things go wrong needs more heat to remove the component. also not so good especially for boards with VIA's (connections between board layers) which can be a PITB to clean out the board component mounting holes IMHO.

I use a low melt solder which is expensive but makes the work easier for my club handed work.

try this next time you want to work

http://www.ebay.co.uk/itm/CARDAS-QUAD-EUTECTIC-SOLDER-3-5M-LENGTH-FOR-HI-FI-CABLE-/171011835460?hash=item27d1198644:g:3LsAAOxyTjNSc-5S

Flows like butter and lovely should you need to repair or rework. Also great for SMD work which I'd be more that happy to help you with.

it's pricy solder but worth every penny IMHO.

Sorry for the OT guys.

I'll try to be more controlled in future

uglymusic

We very seldom get hot under the collar about thread drift - in fact Ben is the master of epic thread drift, although strangely uninvolved with the ancient art at the moment ;-)

If we get enough drifted stuff, we just cut it out a start a new thread. Simples!

shoom

Yes I've noticed but just wanted to re assure the OP that we are on the case.

BTW the mod outlined in this thread could be a good place to start your soldering adventure.

It's fairly straight forward (nothing is easy)and big bang for the £ from what I've read elsewhere.

Get thee a soldering Iron and we'll make a start.

uglymusic

It may well be a good place to start. Good idea.

Although I want to get the IQ DAC up and running first. I'll be grabbing RA this evening, unless I get sidetracked.

shoom

I've not tried I2S on the 3 just USB.

Maybe just have a read of the P3 thread on RA first because I remember reading that some program input may be needed for I2S DACs. Also I can't connect VIA WIFI so LAN only for me ATM.

My Linux skills are just about 0 so I skipped that. BTW the RA android app works great.

uglymusic

As far as I could see, I should be OK. I read a thread or two the other day. 

But it all may be famous last words.

My Linux skills are about 1 on the RPi - things are easier on a 'real' PC, where you can install a full Linux distro that can take care of a lot of things for you. However, I haven't run a Linux PC in years.

shoom

Ok I split the power supplies yesterday and have had the chance for a little listening.

Interesting and not so clear cut as I was expecting.

First up

IFI I Power.

The top end was more extended and the Mids had a little more clarity and detail.

BUT

Where’s the Bass?

He’d gone missing.

Second

Teradac 5V

Better Bass but the sound was a little shut in compared to the IFI.

Third

Anker 5V battery

Had the best balance of the three that I tried.

But with all 3 supplies I tried in my set up overall the sound seemed to lose a little of the fun factor to my ears and IMHO.

So I’ll be pressing on with attack plan B

I2S feeding Teleporters into Buffalo3/Opus/Soekris.

I’ll keep you posted.

uglymusic

You never know until you try, do you?

shoom

Exactly the right way IMHO.

Try and hear for myself.

The I2S unit is nearly ready for er firing up.

uglymusic

Be careful with the terminology.

shoom

Just have a fire extinguisher ready and notified A&E so good to go.

shoom

Spent a good part of yesterday trying to squeeze I2S out of the berry but it did not want to play so I’ve stepped back to the fall back position.

USB-WAVEIO-IFI Purifier2-Buffalo3/Legato.

Sounds good enough for now.

Such is life. I'll do some more reading and have another go later.

BTW anyone using USB out should try the IFI Purifier which re clocks the USB feed from the PI and seems to sidestep the slightly milky presentation of PI direct.

http://www.futureshop.co.uk/product_info.php?products_id=11061

I like it.

uglymusic

Sorry you didn't get it going Shaun.

Shame the IFI Purifier is a bit steep for my office desktop system which does use USB - the spare RPi is headed there sooner or later. But always good to hear about useful widgets.

shoom

No Worries

Failure is an important part of the learning process so just as useful as success.

As an ex windows user I have a few bits and pieces for tweaking things up.

The purifier seems pricy but the difference is noticeable to my ears.

All part of the fun

cj66

There are a few products in the same vein as the ifi Purifier around e.g.

1) The Uptone Audio Regen which is also a reclocker along with alternate power so avoiding the electronically noisey 5v bus from the USB feed.

2) The Intona Isolator which is claimed to be a superior "hi-speed" (designed for commercial use rather than hifi) reclocker.


Both of these have been the subject of heated debates as to their usefulness, as always!

I haven't personally tried any as I already have galvanic isolation and cleaner USB power on my DACs so it seems a little pricey for just reclocking!

http://uptoneaudio.com/products/usb-regen


http://intona.eu/en/products

cj66

Re above, Intona is an Isolator not a reclocker. Fingers ahead of brain or summint ... Doh!

shoom

Yes Chris Regen pretty much the same thing as the IFI unit and as you say have caused heated debate.

my take is this

Effectiveness depends pretty much on the quality of the USB source which on the PI is pretty basic. it shares PSU rails with the Enet which may not be the best idea. Also the PI XO may also be a little basic so re clocking may be even more useful IMHO.

BTW

Both units are based on USB hubs so I wonder which ones as a DIY option would be nice. £90 is well spent helping the PI IMHO.

And you know my opinion of clean USB power lines from our past work on Alex's USB power injector which I still use BTW.

I'm using a Teradac 5V PSU ATM to power the hungry WaveIO and I like it quite a bit abd it's way more convenient than the 5V TP shunt that I had in that spot previously.

Now that was a hot dog.

sondale

The Uptone Audio Regen's main function is NOT as a reclocker, power cleaner; you need to read the threads on ComputerAudiophile to get the technical details but basically what it is regenerating are the data packets. 

I have two of them and I would recommend them to anyone using USB from their computer.

cj66

Yes, you are absolutely correct, I shouldn't have lumped it in with the standard reclockers. I have followed the CA threads with interest.
Although, in my defence, I did provide the links for both products so readers could obtain the low-down from the horses mouth

To Quote;

"The USB REGEN takes the digital audio stream from your computer or other music streaming device, and generates a completely new USB data signal to feed to your DAC.  It accomplishes this by combining a carefully chosen USB hub chip with an ultra low-noise regulator and low-jitter clock.  Importantly, it does so with ideal impedance matching—right at the input of your DAC."

sondale

cj66 said:

Yes, you are absolutely correct, I shouldn't have lumped it in with the standard reclockers. I have followed the CA threads with interest.
Although, in my defence, I did provide the links for both products so readers could obtain the low-down from the horses mouth

To Quote;

"The USB REGEN takes the digital audio stream from your computer or other music streaming device, and generates a completely new USB data signal to feed to your DAC.  It accomplishes this by combining a carefully chosen USB hub chip with an ultra low-noise regulator and low-jitter clock.  Importantly, it does so with ideal impedance matching—right at the input of your DAC."

And I of course did not follow your links!!!:\">

I think Uptone Audio's problem is the name "Regen" which is used by other people, in its full form, to signify regenerating the 5volts.

shoom

sondale said:

The Uptone Audio Regen's main function is NOT as a reclocker, power cleaner; you need to read the threads on ComputerAudiophile to get the technical details but basically what it is regenerating are the data packets. 

I have two of them and I would recommend them to anyone using USB from their computer.

I've followed the CA thread with some interest and twitched over ordering the Regen for a while.

to explain.

Chris and I go way back dabbling in dedicated VBUS power supplies and we where accused of being MAD at the time (which we are a little), now it's ''almost'' standard practice. So we've tried quite a few bits and pieces in our time and reached our own conclusions based on what we hear.

maybe the use of the re clocker word was not quite right but we all can get a little stuck terminology wise at times.

Could you Give some thoughts on the affect if any when used on your PI? I noticed a clear difference in clarity and body sound wise with the IFI purifier 2.

BTW I also use an audioquest Jitterbug on an adjacent USB socket and the effect is errrr subtle at best but I have dedicated VBUS anyway so maybe it matters less.

I'm tempted. 

sondale

Message sent to CJ66 and Shoom regarding Regen.

shoom

And replied to.

Sounds like fun

shoom

And for the sake of conversation

I became interested in the regeneration subject from a totally different angle after reading through this thread.

http://jplay.eu/forum/index.php?/topic/1710-ethernet-switch-increase-in-sq/

I’d been using Jplay from version 1 BTW but find the little PI pretty good so have stuck with that.

But hang on I hear you thinking, that’s an Ethernet switch.

Here’s from the Original poster.

‘’My theory is - the switch is a store-forward device - it looks at every packet it receives and does an integrity check on it  before sending it on -  if there's any problems then it requests a resend. So, all the NICs in the chain are guaranteed 'clean' packets,  less  overhead on the NIC - obviously there is increased latency with this, but this is irrelevant with audio streams at Gb speeds.’’

I had a pretty old switcher in and replaced it with a Cisco unit and well blow me it sounded different and better in my set up.(I still use it for my network BTW)

I wondered if the Regen/IFI units are using the same sort of methods for USB.

When the Regen was first mooted I was interested but forgot with time until I acquired the IFI IDAC2 and could not resist the Purifier 2 (it’s not the same as the original purifier BTW).

When it arrived I set it up and forgot all about it.

Then I was fiddling around and forgot to plug it back in.

I thought hey that sounds a little off color. Then the penny dropped.

Plugged it back in and hey presto all seemed better.

Tried it with my other USB DACs and its goodness seems to depend on what it’s plugged into.

With the WaveIO/Buffalo 3 it’s really rather good to my ears and in my set up.

The taking out test may prove more revealing than a ten minute listen but for sure  they won’t turn Pinky and Perky into Mozart so system integrity may also matter.

The Regen handles VBUS also so that’s going to be interesting.

sondale

Nowt wrong with Pinky and Perky - I remember with fondness!

shoom

)

cj66

sondale said:

Message sent to CJ66 and Shoom regarding Regen.

Also replied to.

cj66

For those who have not yet experimented with substituting the 5vBus supply for a cleaner/better one, here is a succint post that tells you all you need to do for your first, simple and very cost effective delve into the murky waters of improving USB audio.

http://www.whathifi.com/forum/hi-fi/usb-dac-power-tweak

sondale

When I was using the Exasound USB to I2S I cut the both the +5v and Gnd wires in the USB cable (very carefully) near the dac, stripped them back and fed a clean 5volts into the Exasound via these cables. One of the things I learnt from this and other experiments was that if the 5volts from the computer is not needed then that wire can be cut, but the Gnd may be needed as may the Screen connection - it seems to depend on how the computer recognises that the USB port is active. It is fairly simple to make up USB cables for testing what is needed in your setup before embarking on chopping your expensive cables. There seem to be a lot of cables around nowadays which have all combinations including the Gemini types which keep the power as far away as possible from the data wires.