Q11-Q12
Q3-Q4
are more sensitive to the matching, so use better matched couple there.
Still you can do with no matching if all BC550/560 are in that range. DC servo will keep DC offset close to zero anyhow(it will take a few second to settle).
For some people the gain of the GainWire mk2 set to 6.5 times could be to much in today time of digital sources. To lower the gain to more appropriate level of 3.5 time just two resistor in each channel need to be changed.
R17 from 2.7k to 1.5k
R19 from 100R to 330R
Damir
R17 from 2.7k to 1.5k
R19 from 100R to 330R
Damir
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Finally completed this project. After a quick listen on headphones, I am impressed. No harshness at all.
Not sure which mode I prefer yet. More listening required later today. 🙂
Dadod,
Would like to make another one for my Pre amp project. Would it be possible to have pdf (or similar) of the track layout to allow me to make a home made PCB? I saw one earlier in the thread but it had the silkscreen included.
Many thanks
Paul
Not sure which mode I prefer yet. More listening required later today. 🙂
Dadod,
Would like to make another one for my Pre amp project. Would it be possible to have pdf (or similar) of the track layout to allow me to make a home made PCB? I saw one earlier in the thread but it had the silkscreen included.
Many thanks
Paul
Hi Paul, Do you need mirrored image for iron method?
I expect, soon, your more detailed listening report here.
Damir
Hi Damir,
Mirrored image would be great. Thank you.
Currently listening to your line amp. At present I'm leaning towards the "with negative feedback" setting. I find the ngfb setting more lively but not as easy to listen to. There's not a lot in it, both sound good, but I think I prefer "with feedback".
With negative feedback, I could listen to this for hours. It's crystal clear with a nice smooth sound. When a track has bass there is no sign of any struggling just a very clean effortless/controlled sound. Very nice!
Vocals are very good.
More comments will follow...
Look forward to building this into my preamp... Will be interesting.
Paul
With reference to Fig.3 of post #431, is it possible to replace the Output devices with 2SC5200 and 2SA1943? Thanks.
Damir, mirrored image of PDF for iron-transfer for me too. Thanks,
Damir, mirrored image of PDF for iron-transfer for me too. Thanks,
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Sorry Sam, mcd99uk bought one PCB from me, so I offered pdf to him.
I hope I will offer more PCBs soon, so you could buy one too.
Damit
This is output impedance in CFA mode without output resistors. I added 33R for the lineout and 47R for the headphoneout, so those are actual output impedances as that of the preamo is quite low.
Damir
Attachments
Why does the output impedance increase from <30milli-ohms to >1ohm, when the NFB loop is closed?
I have my OPS optimised for higher input impedance,(have fitted a Jfet input pair) Now it works perfectly with Damirs current conveyor IV-IPS
I have altered Damirs input stage a bit, as to be able to put input filtering after the level shifters.
Anyway it will be interesting to evaluate the two
circuits, and also the folded cascode developed to be a full scale global NFB amplifier
I will build and listen to all three versions over the next few months.
The screen shots show the two amplifiers (Damir's and the folded cascode) at 1W 1KHz and 15-16V 20 KHz, in one case the limiting factor is the Voltage amp, i the other it's the other way around, But I really like the structure and NON feedback nature of Damirs current conveyor IV-IPS.. and the performance is more than good...
Don't really know what to expect sound wise, It'll be very very interesting.
I have altered Damirs input stage a bit, as to be able to put input filtering after the level shifters.
Anyway it will be interesting to evaluate the two
circuits, and also the folded cascode developed to be a full scale global NFB amplifier
I will build and listen to all three versions over the next few months.
The screen shots show the two amplifiers (Damir's and the folded cascode) at 1W 1KHz and 15-16V 20 KHz, in one case the limiting factor is the Voltage amp, i the other it's the other way around, But I really like the structure and NON feedback nature of Damirs current conveyor IV-IPS.. and the performance is more than good...
Don't really know what to expect sound wise, It'll be very very interesting.
Attachments
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NGFB = negative feedback
No GFB = no global feedback.
Look at the Thread title for the clue.
But I now see that connecting the feedback lowers the output impedance as is normal.
No GFB = no global feedback.
Look at the Thread title for the clue.
But I now see that connecting the feedback lowers the output impedance as is normal.
Sorry my bad, I was thinking that is enough to write No Global FeedBack as we don't need positive feedback in audio amps (I know is not always so).
Hi MiiB, very interesting twist in your IPS, just two things. Did you simulate with square wave and noise? Did caps from the bases of Q19 and Q22 to the ground slow the IPS, and the low values CM resistors and high values of the I/V resistors could be a reason for high noise?
cheers
Damir
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