Pass D1 I/V Stage PCB

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#161
what you might like to try is shunt some of the excess current to ground, perhaps a pot would be useful so you can experiment with what value to use?

BTW how do you measure the output, do you have sinewaves you can look at with a scope?
 
#162
Yunick said:



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 🙂
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Yunick - I'm not at home , reading from "strange" PC ;
can you give me direct link for schematic you use , maybe I can help with output level issues .......
 
#163
Luke said:
what you might like to try is shunt some of the excess current to ground, perhaps a pot would be useful so you can experiment with what value to use?

BTW how do you measure the output, do you have sinewaves you can look at with a scope?
Click to expand...

Yes a shunt would work. I might try that. The output voltage number came from simulation. I have only tried it with my UGS preamp. Over at UGS adventures I read that max input of the UGS preamp is +/-4V. If I lower the volume on the squeezebox it works fine. But not with my CD-player or Turntable. The scope is still at work but I can measure it next week.


Zen Mod said:



Yunick - I'm not at home , reading from "strange" PC ;
can you give me direct link for schematic you use , maybe I can help with output level issues .......
Click to expand...

Zen Mod 🙂 Good to see you here 🙂

I used this Schematic and tried the circuit with half values of R15 (1.6k) / R16 (750r). From what I understand those resistors set bias and gain?
I would be very happy to if you could take your time and have a look 🙂
 
#164
It looks like R17 is the I/V resistor which is what you would want to adjust to change the output level. The 1.5k that is there would suggest it is setup for a TDA1541a with 2mA output current. I would leave the values of R15 and R16 alone, but I'm not extremely familiar with the D1 stage.
 
#165
Yunick said:


........ 🙂
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instead R17B use two resistors of 750R in series

then solder C3B to their mid point

make same game with right side out - with R17A and C3A

that way you'll have 50% of present output

that's easiest way of decreasing output without going too deep ;

btw- take a look at CeeVee's Drekling I/V stage (Shanling thread in Digital) - cheap and worth trying
 
#171
Hi there! I build me the IV stage in an parasound 1500 dac. Its hardwired. I connected the board to the pcm63PK and measured on the input 965mv and the output is drifting between 10mv and -4mv. Should I use the cermet pots to bring the input down? I connected the jumpers. Before I did that, offset on in and output was drifting from 60mv to 45mv on the inputs and outputs, but after an hour offset was at all points 0 mv, and there was no music. The cdplayer locked. Can I give it a try? Or will I destroy something. Grtz Teake
 
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