My_Ref Fremen Edition - Beta build/Fine tuning

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#1,463
Marra said:
Would Amtrans be a possible substitute for the Rikens?TIA
Click to expand...

Just yesterday I installed a couple Amtrans resistors in the output path of my active xovers. They impart a smooth, spacious quality that I didn't have with PRP's in place; very pleasant. I suspect these are the same qualities people like about the Rikens, and should be used sparingly. I expect that they would exhibit those same qualities in the FE amp. They are one-half inch long, though.

Peace,
Tom E
 
#1,466
Way off topic

Some of you may have noticed that I changed my avatar.

This weekend, I found the device in my avatar in my father's desk drawer. It is an original George Philbrick Op Amp using tubes from 1952. My understanding is that it is the first op amp ever produced commercially. I felt like that deserved a minor place of honor, even above Frank.

By the way, it is sitting on a coil of solder and the op amp is about 55 mm in diameter and about 120 mm tall, including tubes.

Jac
 
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#1,467
lehmanhill said:
Some of you may have noticed that I changed my avatar.

This weekend, I found the device in my avatar in my father's desk drawer. It is an original George Philbrick Op Amp using tubes from 1952. My understanding is that it is the first op amp ever produced commercially. I felt like that deserved a minor place of honor, even above Frank.

By the way, it is sitting on a coil of solder and the op amp is about 55 mm in diameter and about 120 mm tall, including tubes.

Jac
Click to expand...

Not too far off topic; its historical. Post a proper picture of it😀
 
#1,472
The boards arrived also here and in the weekend i will start some soldering. They look stunning and they are a bit bigger that seem to be in the pictures.
Any opinion about Kendeil lytics or any other suggestion apart Mundorfs ? I was thinking to buy 4 of them 15000uf/40v
 
#1,475
No.
assuming the mains voltage is Vac and the regulation is R percent:
The DC voltage will be ~
Vdc = Vac / Vspec * Vsec * [R/100}+1 - Diode Vdrop.
For a 115/230:25+25Vac 7% regulation transformer running on 127Vac (maximum mains tolerance) and delivering zero output current (except for smoothing capacitor leakage current) expect ~ +-42.3Vdc
When the chipamp/s is/are drawing quiescent current expect the PSU voltage to drop ~1V to ~+-41Vdc.
This within the maximum specification of 84V given by National for their 3886 chipamp.

Your mains voltage will vary by ~+-6% either side of nominal.
 
#1,477
AndrewT said:
No.
assuming the mains voltage is Vac and the regulation is R percent:
The DC voltage will be ~
Vdc = Vac / Vspec * Vsec * [R/100}+1 - Diode Vdrop.
For a 115/230:25+25Vac 7% regulation transformer running on 127Vac (maximum mains tolerance) and delivering zero output current (except for smoothing capacitor leakage current) expect ~ +-42.3Vdc
When the chipamp/s is/are drawing quiescent current expect the PSU voltage to drop ~1V to ~+-41Vdc.
This within the maximum specification of 84V given by National for their 3886 chipamp.

Your mains voltage will vary by ~+-6% either side of nominal.
Click to expand...

Ok thanks Andrew. I forget where I got my estimate. Maybe one of Sloan's books? 42Vdc sounds too high for this project, or am I wrong?
 
#1,478
+-42Vdc (84V) is the National specified maximum for a 3886.
Your normal mains voltage is <<127Vac.
Measure your supply voltage without killing yourself. Then you can predict what to expect from your PSU before you buy it.

BIG OOPS.
I omitted the sqrt(2) term from the above calculation.

Vdc ~= Vac / Vspec * Vsec * [R/100}+1 * sqrt(2) - Diode Vdrop.
 
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