Pass D1 I/V Stage PCB

[steenoe]

I know nothing about a Squeezebox, but:
What kind of signal is comming out of the squeezebox? I cant help wonder, how you can adjust the volume of that signal. Usually you cant, when dealing with digital signals. Is it SPDIF or I2S you are feeding into that Buffalo?



BTW. I have no clue what input bias is, it was you who started that a few post's back

 

[Yunick]

I'm feeding it with SPDIF.

The squeezebox have volume control built in. I don't know how it works thou.

 

[steenoe]

I'm feeding it with SPDIF.

In that case, it is gonna work. Now back to fine-adjusting the thing

 

[Yunick]

cool beans

Thanks again for the support Steenoe.

 

[Yunick]

Hi again,

As you know I use the ESS Sabre DAC chip from Twisteadpearaudio together with D1. According to Russ White the Sabre DAC spit out ~8mA. Look here .

From what I understand this is twice what the D1 is designed for?
So to make this work, could I reduce R6a and R2a to their half value? Or maybe R3a? Schematic here ->

Best regards

 

[Yunick]

Hi All,

From schematic above:

To modify the D1 to work with 15mA p-p.
I assume that I can replace R2a with 200r and R6a with 133r. With this adjustments I'll keep the output impediance with a output of +/-2Volt? Only drawback may be a 2.7W heat from T1a :/

 

[steenoe]

Hi All,

From schematic above:

To modify the D1 to work with 15mA p-p.
I assume that I can replace R2a with 200r and R6a with 133r. With this adjustments I'll keep the output impediance with a output of +/-2Volt? Only drawback may be a 2.7W heat from T1a :/

Did you do that mod, and did it work? I am sorry to be of so little help on this, maybe someone else could tune in? Unfortunately I never tried to modify the D1.

 

[Yunick]

No, I haven't yet tried it. I was hoping someone would comment on my ideas . The r values are really low from the original circuit but according to my calculations that seem to be correct.

What chip did you connect your D1 to?

 

[steenoe]

TDA1541A, and that worked well. The TDA is pretty much defacto on the output current.

 

[Yunick]

Aha..

I'll try modify some r values tomorrow and see what happens. I tried the Sabre with passive I/V tonight. The D1 is really makes a big difference.

Thanks alot for your helping me out Steenoe.

 

[khundude]

Ok, I am about to order parts for my D1 I/V stages. One is for a buffalo DAC and the other is for another PCM63 project later. I want to figure out what the best part for the job is and what voltage, so opinions please.

C1/C2-100nF
C1A/C1B-10nF
C2A/C2B-2700pF
C3A/C3B-4.7uF
C4/C4A/C4B/C9-220uF


Also, where is good place to get the pots? Has anyone settled on the Shiny group buy?

 

[zei]

Hi

Farnell has all the parts you need, And hopefully someone has allready the partnumbers in a nice excelsheet or something


Regarding the Shiiny i do not have a complete layout for it and i can not tell when it is expected.
There are however others that made nice layouts for it. If you do a search you will proberly find it

/JZ

 

[khundude]

I am sure Farnell has the parts, but has anyone thought of boutique caps and such? Will Black Gates fit?

 

[khundude]

If I can get the parts at Digikey in Canada in would be cheaper. Also, while I have the BOM I cannot be sure which parts to order as I kind find any desription other than the value. I am just guessing with this info and my guesses are bad.

 

[Yunick]

........Will Black Gates fit?.....

I use 10µf 50V BG N as output caps. I fitted them under the PCB with 5mm leads left. It does sound great.
From the beginning I used RIFA PHE426 4.7µf but they where a bit big.. I had the BG caps laying around so I tried the out..

If you look closely you can se the BG sticking out under the PCB..

An externally hosted image should be here but it was not working when we last tested it.

 

[Yunick]

C1/C2-100nF
C1A/C1B-10nF
C2A/C2B-2700pF
C3A/C3B-4.7uF
C4/C4A/C4B/C9-220uF

For those locations I use Rifa phe, Wima MKP, Silver mica, Balck gate ond Pana FC. In same order

 

[khundude]

Will 1/2watt PRP resistors with 1.0cm lead spacing fit on this board or can I use 1/4watt resistors?

 

[zei]

1/2W resistors wont fit i guess.

You will have to use 1/4W unless you want to place them vertical (tilt them)

I think Steenoe did that on his board.

/JZ

 

[Luke]

Zei, nice setup
I was considering the same rig, squeezebox, buffalo and then D1 I/V.
Did you get it to go properly, or is the output still too high?

BTW are you listening to MP3 or flac files? Flac through a squeezebox with a good dac is incredible. Mp3 is limited. Ive heard this with an opus balanced out into my aleph 2s, and I was inpressed.

 

[Yunick]

Zei, nice setup
I was considering the same rig, squeezebox, buffalo and then D1 I/V.
Did you get it to go properly, or is the output still too high?

BTW are you listening to MP3 or flac files? Flac through a squeezebox with a good dac is incredible. Mp3 is limited. Ive heard this with an opus balanced out into my aleph 2s, and I was inpressed.

I haven't had the time to fiddle with it more. The output is still high (i think 6V p-p) because of the buffalos higher mA output. This caused my preamp to clip..

For now I use the built in volume control in the squeezebox then feed direct to my power amp. This is for me a very good combination. I use mainly Flac, but sometimes mp3 also. But never during critical listening. With 88db spks and 15db gain in poweramp full volume on the squeezebox is just right

The sound is just awesome! Powerful describes it good.. Alot of drive