I'm not sure what discrete output stage you built (Ray's?) but it should be approx. the same volume as the opamps. This will depend upon the I/V resistor (for lack of a better term) that you used on the discrete. If that is correct, then you have some other problem on the I/V stage.Thomo said:
Thomo said:
Hi Lee,
Good to hear it works! Like Pars mentioned, it should be the same output as the opamp filter. Are you sure you have both RO/RON and LO/LON connected correctly? Otherwise you only get half the output.
The buffer is the single-ended output transistor/FET in this case. The circuit should be able to drive a 10k pot with only a little signal loss. The output resistor is 1k8, so that's over a factor five smaller.
BTW, there is no I/V in this case, the SM5872 DAC is voltage out.
Ray
Thanks for your comments guys. My volume pot is a 50k Alps Black Beauty. I sorted the connections but the volume is still really low and sounds odd. There's loads of detail and separation, so I know it'll be good in the end. What it is doing right, it is doing very, very right. Thanks for a great design Ray.
I think Mappo's labeled my resistors wrong, noobs. So I'll build another one soon.
Lee.
I think Mappo's labeled my resistors wrong, noobs. So I'll build another one soon.
Lee.
Success
Hi
Finally lost the outboard dac (sony bla bla) and understand that I just started..
Actually The digital PSU is updated and the Analog just received the raygulator treatment (with some schottkys).
The output opamps are now LM4562NA and the sound is finally on par with the sony in terms of definition.. (I still miss the lateral dimension.. the sound is a little "smaller" now) but the timing and pace is much better.... This player can relly sound good..
The sound is much more coherent now (easier to listen to).
I am building new regs for the Analog psu... can I raise the output voltage to improve dynamics ?
How much will the LM4562 take ?
Regards
Ricardo
Hi
Finally lost the outboard dac (sony bla bla) and understand that I just started..
Actually The digital PSU is updated and the Analog just received the raygulator treatment (with some schottkys).
The output opamps are now LM4562NA and the sound is finally on par with the sony in terms of definition.. (I still miss the lateral dimension.. the sound is a little "smaller" now) but the timing and pace is much better.... This player can relly sound good..
The sound is much more coherent now (easier to listen to).
I am building new regs for the Analog psu... can I raise the output voltage to improve dynamics ?
How much will the LM4562 take ?
Regards
Ricardo
Thomo said:
I took a quick measuring with my scope. Mine gives 2Vpp (actually 2.4Vpp) so it's comparable with the opamp filter.
I created a set of test tones with http://sourceforge.net/projects/wavb
Burned them, checked them with EAC wav analyzer that they were at 0db, and then I did the measurement.
Don't you have a DMM so you can check the resistors values ?
avr300 said:
Erm, yes. But I kinda rushed it as time has been a little limited and it had been sat all week almost finished and impatience got the better of me. I know I should have measured them. I am going to make another set of boards and do a "proper" one with premium parts.
Cheers,
Lee.
Pars said:
It appears that you have a DMM? If it were me, I might do something like check DC offset at the output of the preamp with the CD player selected and on to see what that 22mV does further down the chain
I have not removed the output caps on the CD53 so this offset does not enter the preamp. I am afraid to touch the inside of the preamp because it is an old Meridian 101 (30 years allways playing) and the cables might break.
Maybe I must replace the output caps with something better... I have two ELKO Visaton 470uF 63V bipolar caps... Can you advise on this replacement ?
Best Regards
RCruz said:
You have 22mV of offset on the output of the CD player, AFTER the coupling caps? Yes, I would replace them with something like 47-100uf BlackGates (6.3V or 16V) NX or K series. Or film caps, but I am not sure how low you can go in value here without affecting frequency response.
RCruz said:
Hi Ray
I finally have the rayregs built but as I could not get the values you indicated, I chose 120 ohm for R1 and 1047 for R2.
R2 is paralleled with a tant 10uF.
To stabilyze the output, I put a cap 16uF tant betwwen ground and +-12V output.
The output is now 12.25 Volts +-.
Can this hurt the opamps ?
Regards
RCruz said:
No, 12.25V is no problem. Most opamps can handle +/- 15V easily.
Only AD8610 and 8620 have a maximum of +/- 13.5V.
Yes, you could, but it's no use in this case. The lowest frequencies are already passed through perfectly with a 47...100u cap. And a bigger BG would only be more expensive.
Regards,
Ray