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
Yes, LM317 used as a CCS has better rejection than LM337 as CCS.
See http://waltjung.org/PDFs/Sources_101_P2.pdf
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
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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35V is a too low rating for long therm use, it may work while you wait for 50V rated caps.
This looks like a cool project. I have a pair of Avel 250VA 25V+25V torroids like this one:
Avel Y236652 250VA 25V+25V Toroidal Transformer 122-625
Can I use them for these boards? With 25Vac secondaries I'll get around (25 * 1.4) - 1 = 34Vdc. Right?
Avel Y236652 250VA 25V+25V Toroidal Transformer 122-625
Can I use them for these boards? With 25Vac secondaries I'll get around (25 * 1.4) - 1 = 34Vdc. Right?
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.
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.
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?
+-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.
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.
After searching the older Mauro Penasa MyRef thread, I found that this guy in post 1500 used the same transformer:
http://www.diyaudio.com/forums/chip-amps/54571-my-audiophile-lm3886-approach-150.html#post764510
in addition to three others. So I should be good to go but will measure them when I get the chance. He also claimed no difference in sound between the Avel 250VA, 330VA and 625VA models.
http://www.diyaudio.com/forums/chip-amps/54571-my-audiophile-lm3886-approach-150.html#post764510
in addition to three others. So I should be good to go but will measure them when I get the chance. He also claimed no difference in sound between the Avel 250VA, 330VA and 625VA models.
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