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Buffalo II - Assembly for the Electronically Bewildered part III

Themystical paid around 99USD for a sabre 9018 board with the 9018 mounted which is quite a bargain. The 9018 is 60UKP alone! The board is otherwise bare but the small smattering of SMD devices needed is cheap. Takes a couple of hours to stuff one. He built a pair for a dual mono set up. I've heard them and they are fine.
He was initially worried about the SMD stuffing have never done any but he now gets along fine given a little tip or two.
 
yeah I hear that, but it's all the bloody regulators and all the room needed, when speaker developing the flexibility is the most important thing. One day when I've got money to burn I'll get a top of the line studio interface I think.
 
Some light weight modifications today.

Mucking about up the loft I found a rack, so this will improve things over the wobbly table I thought. Also found an air isolation table thingy and some squidgy foculpod whatnots.
All installed and the sound quality sort off...


Well absolutely no change :D

IMG_2431_zps1f63ec52.jpg


IMG_2429_zps5761a45d.jpg


The other thing I tried was running the Rpi (piCoreplayer) from a Placid rather than a plastic wall wart thingy. Some where in the past I changed something that started to cause lock drop outs and long since forgotten what it was. The thing changes so much that I lose track of what is what. So some days I have to open up the DPLL to perhaps as high as medium to get consistent lock, other days it will run on the lowest window, some times it varies every few hours and is always worse at night.
I seem to remember it was best when I used the WaveIO as the Buffalo clock instead of letting the Buffalo do an ASRC. I was hoping the Placid may help with drop outs, seemed good and running on lowest DPLL. Now as I type this post I can here a few drop outs. I also notice in the picture the Quantiser is set on 8bit pseudo which is not my normal setting, a sign of too much fiddling.
Also the Placid is not fed from my standby circuit so the DAC powers down in auto standby but can't power back on. Far too much fiddling today.
 
Mentioning Paul Hynes - wonder what his situation is these days?

I'm getting a DIY itch again, maybe try feeding my old Buff. from a Pi but haven't a clue. Need to do a bit of reading!
 
Hi Tony the pi thing is easy.
Get a pi, flash an sd card with picoreplayer, stick it in, power up the pi on the lms network and browse to the pi and set i2s on. Default is analogue output so you can plug headphones in straight away and check the lms side works. Simple instructions on picoreplayer site.
Connect four wires i2s from the pi to the buffalo.
Enjoy.
 
Bemused said:
Hi Tony the pi thing is easy.
Get a pi, flash an sd card with picoreplayer, stick it in, power up the pi on the lms network and browse to the pi and set i2s on. Default is analogue output so you can plug headphones in straight away and check the lms side works. Simple instructions on picoreplayer site.
Connect four wires i2s from the pi to the buffalo.
Enjoy.
Click to expand...
Ta Tony, that sounds pretty easy. Mind you, perhaps a bit too easy! :D
 
Suffolk Tony said:
Mentioning Paul Hynes - wonder what his situation is these days?

I'm getting a DIY itch again, maybe try feeding my old Buff. from a Pi but haven't a clue. Need to do a bit of reading!
Click to expand...

I would have a word with his sub contract company in Norfolk, Dave is the man to talk to.
 
Thinking about me Buffaloes again!
I use just one Mite regulator to feed the AVcc terminals and for dual mono I common all DAC outputs. This has previously been done with a combination of hookup wire, board header and a strip of vero board.

All a little messy

Also thinking of adding some close proximity ground plane shielding just above the Sabre and clock to maybe aid better locking of the i2s signal.

So I have this idea of a new little board to do the following.
a. Provide shielding.
b. Provide my commoning connections to the Buffalo.
c. Provide board headers for the incoming Mites AVcc supply.
d. Provide board headers for the outgoing DAC outputs.

The existing vero in the "super" crappy picture below

IMG_2018_zps8973c666.jpg


The new little board seems a neat solution to all my points, clip it in and plug in my cables.

Top copper
X3 & X5 are downward facing and common the Buffaloes AVcc terminals.
X4 are upward facing and provide the AVcc termination point.
X2 & X6 are downward facing and pick up the DAC outputs and common them.
I may add SMD jumpers to allow for use with Stereo operation.
X1 & X7 are upward facing and provide the take off point for the DAC outputs to feed my IV stages. Only one of X1 & X7 is used depending on whether its a left channel or right channel board.

Screenshotfrom2015-01-16145534_zps9647f7b8.png


Bottom copper

Screenshotfrom2015-01-16145613_zps26062e05.png
 
Hi guys

Lately I have updated my Buffalo III to Dual Mono Single Legato config. The issue is, it works just with 4 DACs outputs. I can make it work with 4 odd or 4 even DACs and it works fine (regardles of the phase I put on Legato, 4 DACs works in-phase and in-anti-phase to Legato).
Now, i get no joy if i try to sum up all 8 DACs. Again, all DACs are working fine, but i have tried to put them all together in all possible ways and there is just no sound... nothing. Actually, as in the code below the even and odd DACs are in anti phase, it means i have to connect it the official TPA way, it means even DACs + to odd DACs -, and even DACs - to odd DACs +, then again reverse to Legato input..

I thought it could be the current that is to high when i sum all the DACs, as the legato is not modified (the resistors are standard values), but I set the attenuation of both Buffalos to fairy low values and haevent heard about any issues of too high current on legato.

Need help!

Hardware Config:
2xNCORE (balanced in)
2xBuffalo III
1xLegato (balanced out)
Arduino DUE as controller,

code for mono config here:
//------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Register 17 (0x11) (MC5)
|1| | | | | | | | Mono Right (if set for MONO)
|0| | | | | | | | Mono Left (if set for MONO) (D)
| |1| | | | | | | OSF (Oversample filter) Bypass
| |0| | | | | | | Use OSF (D)
| | |1| | | | | | Relock Jitter Reduction
| | |0| | | | | | Normal Operation Jitter Reduction (D)
| | | |1| | | | | SPDIF: Auto deemph ON (D)
| | | |0| | | | | SPDIF: Auto deemph OFF
| | | | |1| | | | SPDIF Auto (Only if no I2S on pins) (D)
| | | | |0| | | | SPDIF Manual (Manually select SPDIF input format)
| | | | | |1| | | FIR: 28 coefficients (D)
| | | | | |0| | | FIR: 27 coefficients
| | | | | | |1| | FIR: Phase invert
| | | | | | |0| | FIR: Phase NO invert (D)
| | | | | | | |1| All MONO (Then select Mono L or R)
| | | | | | | |0| Eight channel (D)

//------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| CONFIGURATION | #define DUALMONO | #define TPAPHASE |
|---------------------|------------------|------------------|
| Dual mono in-phase | un-comment | comment |
| Dual mono TPA phase | un-comment | un-comment |
| Stereo | comment | comment |
|---------------------|------------------|------------------| */

#define DUALMONO
#define TPAPHASE //Reverse phase of even and odd DACs

//------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

byte reg17=0x1C; // Auto SPDIF, 8-channel mode, other defaults
// reg17 is used for stereo and for MONO. It is used for both chips
#ifdef DUALMONO
byte reg17R=0x9D; // Auto SPDIF, MONO RIGHT CHANNEL, other defaults. Used for reg 17 right only
#endif DUALMONO

//------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

#ifdef DUALMONO // DAC registers default to stereo. Set to MONO L/R for dual MONO
bitSet(reg17,0); // Set for MONO
writeSabreReg(0x11,reg17); // Sets both chips to MONO
#endif DUALMONO

#ifdef TPAPHASE
// The outputs on each side of each MONO board will be in opposite phase. In order to do this
// the phase of the odd dacs are out of phase with the even dacs. Further, buffalo is configured
// such that (In dual mono mode) the channel on the DAC which is opposite of the selected channel
// carries the same analog signal but in anti-phase (odd dacs are the left channel;
// even dacs are the right channel)
// See http://hifiduino.wordpress.com/sabre32/ for further explaination

writeSabreLeftReg(0x0D,0x22); // MONO LEFT DACx: odd dacs=in-phase; even dacs=anti-phase
// writeSabreLeftReg(0x13,0x00); // MONO LEFT DACBx: all dacs anti-phase with respect to DACx
writeSabreRightReg(0x0D,0x11); // MONO RIGHT DACx: odd dacs=anti-phase; even dacs=in-phase
// writeSabreRightReg(0x13,0x00); // MONO RIGHT DACBx: all dacs anti-phase with respect to DACx
#endif TPAPHASE

//------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 
@bemused...Tony, I notce you've swapped from waveio > i2s > DAC to raspberry > i2s > DAC ... Did the SQ improve by avoiding USB etc on the waveio route?
 
Hi Tomasz,
I can't think straight right now but it will work one way or another with all dacs in parallel.

From memory the TPA method uses two Legato, I know I had Iit working with just one Legato, now I'm on SEN.

I made bridging cables to parallel the DACs, all 8 of them and then fed the cables down to the Legato. Code was set as define dual mono, not tpaphase.
 
Hi Tony,

Thanks for the answear.
Basically, there are not many possible ways to connect the dacs and i have tried all.
First i have done just MONO and put even and odd dacs cross to each other as they are reversed in phase, then cross again to legato. Exactly how it should be, but no joy!?
I have tried the all possible configs and no go with 8 dacs. The even 4 and the odd 4 work just fine and on both channels :/

I have no scope and signal generator, so cannot check if the signal is in phase or antiphase...so its just blind trying.

Anything i can think about would be to high current output, but the signal is at -50 dB at start, so its fairly low :/

No clue!

Thanks again for the answear

Tomasz
 
Its not a current issue, just gets a little loud, I reduced the gain of my Legato.

The answer is in this thread somewhere for sure.
 
Before dual mono I had all the dacs on the left side of the buffalo in parallel with jumpers under the board, like wise with the right hand side.

Just from my memory, when I went dual mono I made a jumper cable to connect the left side to the right side and set define dual mono, so both sides in phase.
 
It will be in part II or part one of this thread if your feeling brave enough for clicking through.
Just looked at the beginning of this part III and I was already dual mono.
 
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