hi,
this is a 3 years old reply, but want to try this now. Would you think using a «single small signal jfet CCS» , such as 2sk170 ~6ma idss , instead of the 470R resistor may cause any major problem to try? Maybe a ccs would give a bit better rejection of ripple?
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Opps, after review, i think i have to study the regulator a bit better.... i did not pictured the mosfet polarity correctly! mosfet Vgs would mostly only varies with total current.
Not sure if it would also oscillate with a CCS. Try it as replied back then with a resistor because I had probably simulated it.
Hi Salas!
I am very sad that I found about this project too late! Well, better late than never.
I am building this preamp and making my custom pcb.
I was wondering if I could use PANASONIC ECPU 1210 1uF 16V capacitor for C3 and C4 positions. I guess they will never see close to 16V.
https://industrial.panasonic.com/cdbs/www-data/pdf/RDI0000/ABD0000C178.pdf
Any help is appreciated
I am very sad that I found about this project too late! Well, better late than never.
I am building this preamp and making my custom pcb.
I was wondering if I could use PANASONIC ECPU 1210 1uF 16V capacitor for C3 and C4 positions. I guess they will never see close to 16V.
https://industrial.panasonic.com/cdbs/www-data/pdf/RDI0000/ABD0000C178.pdf
Any help is appreciated
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That looks really good to me. Really good...like minty fresh.
Indeed. Kostas deserves your congratulations Salas.
He is low profile, therefore I took the liberty to show the details of his wonderful design and assembly.
Healthy and Happy 2025 to all.
George
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Wow! Apparently, photography is another of George's many talents! Looking at this now, it makes me feel I could never build it myself... 🙂
Quick question. For those of you that moved the transformers to a separate chassis, did you find this to make a difference? In other words, how sensitive is the DCG to EMI and whatever else is isolated by doing this?
how sensitive is the DCG to EMI and whatever else is isolated by doing this?
I use a outboard trans, with big caps in separate housing about 4 ft away .. no issues at all .. just a simple metal box, nothing fancy.
I use a outboard trans, with big caps in separate housing about 4 ft away .. no issues at all .. just a simple metal box, nothing fancy.
@Sorenm ... I have 2x Anteks both in the original heavy weight steel cans Antek sells (they have new lightweight steel cans too) in the chassis with the PSU, amp, and muses and other trafos and PSUs...... Amp is dead quiet, headphones as stethoscope ... nothing to hear. Also have trafo tuned quasimodo rigs on the secondaries...fwiw... I can't personally make a case for a separate PSU for this amp...
My 2016 prototype showed mains frequency interference 50Hz level at -120dBV. 3rd harmonic 150Hz at -130dBV. Its a single box with two 30VA frame type plastic potted budget quality mains transformers. So DCG3 is not too sensitive for hum and its relatively easy to make quiet especially if with even better quality transformers.
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Thank you Salas and Pfarrell. I think this settles it: keep it simple and in one chassis.
Cheers,
Soren
Cheers,
Soren
Hi everyone!
I would like to hear your opinion on my power supply approach.
I plan to use two IRM-15-24 (15W, 24V) SMPS modules for the power supply. They will have LCLC filter, pre-regulation for voltage dropping, and TPS7A47/33 LDOs for each channel to regulate down to 17V.
My problem is that SMPS modules come in 15V and 24V, with nothing in between. So, my only option is to use the 24V version.
Because of this, I need pre-regulation to drop some voltage for TPS7A47/33 regulators so they do not overheat.
My question is --> should I use LM317 (or something similar) to drop the voltage or should I only use a big power resistor?
I would like to hear your opinion on my power supply approach.
I plan to use two IRM-15-24 (15W, 24V) SMPS modules for the power supply. They will have LCLC filter, pre-regulation for voltage dropping, and TPS7A47/33 LDOs for each channel to regulate down to 17V.
My problem is that SMPS modules come in 15V and 24V, with nothing in between. So, my only option is to use the 24V version.
Because of this, I need pre-regulation to drop some voltage for TPS7A47/33 regulators so they do not overheat.
My question is --> should I use LM317 (or something similar) to drop the voltage or should I only use a big power resistor?
Use LM317 or something similar. For not to have modulated voltage drop across just an R in the occasion of driving difficult low impedance headphones. If only for line level use, apply an RC in-between for steadier voltage drop and filtering.