Scott,
There are no SMD parts in my design. Check the dimensions of every part for fitting to the parts you are going to use. The gerbers will be sent via pm.
Have a happy and creative new year.
There are no SMD parts in my design. Check the dimensions of every part for fitting to the parts you are going to use. The gerbers will be sent via pm.
Have a happy and creative new year.
Metanastis,
That sounds good Thanks I will keep
A watch for the Gerber file.
Happy New Year!!
Scott
That sounds good Thanks I will keep
A watch for the Gerber file.
Happy New Year!!
Scott
@metanastis: Hi, great work, will you share the gerbers with me - thanks!
All: Wish you all the best in 2024 🙂
All: Wish you all the best in 2024 🙂
Hello guys,
Yesterday night while stuffing my pcbs, I checked the 4R schematic via Andy's BOM. I discovered that C124 for 8R or C6 for 4R has a different value according to the schematic by Hugh. There is a 220uF cap in Andy's BOM. In the schematic, there is a 100Uf cap. I don't know whether is critical or not. Hugh and XRK can answer that question.
Yesterday night while stuffing my pcbs, I checked the 4R schematic via Andy's BOM. I discovered that C124 for 8R or C6 for 4R has a different value according to the schematic by Hugh. There is a 220uF cap in Andy's BOM. In the schematic, there is a 100Uf cap. I don't know whether is critical or not. Hugh and XRK can answer that question.
C124 is the ground shunt cap for referencing the feedback to GND. I think 100uF can work fine. Too small and bass will be affected but 100uF x 820R x 0.7 gives a 17Hz -3dB high pass. Should be fine.
You get 9Hz bass vs 18Hz bass with 100uF. If you have one, use the 220uF it doesn’t hurt. But need to use a bipolar one and 220uF bipolar are rather large.
Hello X,
Would you be so kind as to clarify the question I launched in a previous post:
-Hi, I have a question about the input impedance of the 20w version of the "Alpha Nirvana".
The thing is that I don't know if the input impedance is equal to R1+R2=222,5k, or to R1+R2//R3=22,5k.
Thanks in advance-
Would you be so kind as to clarify the question I launched in a previous post:
-Hi, I have a question about the input impedance of the 20w version of the "Alpha Nirvana".
The thing is that I don't know if the input impedance is equal to R1+R2=222,5k, or to R1+R2//R3=22,5k.
Thanks in advance-
Thank you Anand. Yes I think you are right too. In the 39w version, the input impedance is 22k .
Best regards
Best regards
I really want to give this Alpha Nirvana a try.
My first DIY Amp was the Aksa 55 that I built about 18 Years ago with great assistance from Hugh.
Is there anything that can be optimized for mid/high range in an active system?
Klaus
My first DIY Amp was the Aksa 55 that I built about 18 Years ago with great assistance from Hugh.
Is there anything that can be optimized for mid/high range in an active system?
Klaus
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Klaus,
See my post here for some tricks and tips. This amp is rather transparent in the midrange and top end.
Best,
Anand.
My apologies guys, I have been distracted by holidays.........
220uF for feedback shunt cap is fine, slightly better bass than 100uF but whilst you will set it in the math and the measurements it makes almost zero effect on the subjectives. Bass is already very strong with this amp, and has a rising damping factor below 1KHz.
Input impedance of the AN39 is R2//R3 and also in parallel with the Zin of the base T1. I had not realised this until now, and this means the Zin of the AN39 is dominated by the base input, not simply R2//R3 I had thought before.
The Zin of the base is:
Rin = Beta * (Vt/Itot) * 4, with Vt = kT/q , about 26 mV at room and Itot = The total emitter current of the transistors. (2.6mA here)
This gives about 100 x 26/2.6 x 4 = 4k
So when you put in 22.9k, the combination of R2 and R3 with the base impedance, you get 3k4!
This is a lot less than I'd expected, but could be hugely by adding degen resistors on the LTP transistor emitters.
Cheers,
Hugh
220uF for feedback shunt cap is fine, slightly better bass than 100uF but whilst you will set it in the math and the measurements it makes almost zero effect on the subjectives. Bass is already very strong with this amp, and has a rising damping factor below 1KHz.
Input impedance of the AN39 is R2//R3 and also in parallel with the Zin of the base T1. I had not realised this until now, and this means the Zin of the AN39 is dominated by the base input, not simply R2//R3 I had thought before.
The Zin of the base is:
Rin = Beta * (Vt/Itot) * 4, with Vt = kT/q , about 26 mV at room and Itot = The total emitter current of the transistors. (2.6mA here)
This gives about 100 x 26/2.6 x 4 = 4k
So when you put in 22.9k, the combination of R2 and R3 with the base impedance, you get 3k4!
This is a lot less than I'd expected, but could be hugely by adding degen resistors on the LTP transistor emitters.
Cheers,
Hugh
That's a bit low for general use, I would've thought, Hugh?
Luckily for me, the Zout of the Topping E30 DACs I'm using (which feed my ANs) ... is only 20 ohms!
For those who need to do this - because their preamp/DAC doesn't have a very low Zout - how are they going to fit these degen resistors onto the PCB?
That helps allot thanks.
I didn't read the whole thread so excuse my ignorance.
Are there any boards around or do I need to create my own?