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Old 10th May 2008, 08:02 PM   #671
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When trying to push the limits of ultra-simple circuitry, aren't these coincidences sort of inevitable? I mean, Nelson Pass is just about the last guy on the planet I'd accuse of a lack of originality.
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Old 10th May 2008, 09:04 PM   #672
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Quote:
Originally posted by mrothacher
When trying to push the limits of ultra-simple circuitry, aren't these coincidences sort of inevitable?
Yes, although I like to put a little more distance between offerings.
Both are push-pull complementary feedback pairs with voltage gain.

That said, the details of the circuits and the performance are different:
Vertical vs Laterals, the amount and arrangement of feedback, the
bias values, the power supply values, how the adjustments are
accomplished, the power rating, damping factor, gain, and distortion.

They do appear to have about the same bandwidth.

Also the circuit appears in two different Selectronic products, one a
4 channel amplifier designed to accommodate bridging, and another
a monoblock with a chip for a balanced input.

I'm sure they are both fine sounding amplifiers.

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Old 10th May 2008, 11:38 PM   #673
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Quote:
Originally posted by seventenths
Well I lucked out and picked up one of two copies of AxP that hit my local bookstore! I sure hope I don't appear to be TOTALLY self- absorbed, reading the article during my sons little league game, but a mans gotta do what a mans gotta do


7/10
The proper thing to do would have been to get the second
copy for your son.
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Old 11th May 2008, 12:47 AM   #674
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Quote:
Originally posted by Dennis Hui


The proper thing to do would have been to get the second
copy for your son.
... well, I did fill out the subscription card for my wife's Mother's Day gift .She loves me RIP she loves me not RIP she loves me RIP...


it's settled, she loves me,
7/10
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Old 11th May 2008, 01:30 AM   #675
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Quote:
Originally posted by defect9


...one question though, if I wanted to add a headphone out (for late night listening), what are some good ways to do it?


Quote:
Originally posted by GRollins


Either add resistors to cut the power down or build a dedicated mini-version.


Quote:
Originally posted by defect9


I definitely don't have the know-how to pull off designing a mini version yet.


Quote:
Originally posted by Variac


But Grey does!


Give me a day or a week or a month...or something. I've been wearing my farmer hat today (tomatoes, peter peppers, basil) and about a hundred other things, plus I'm trying to find time to put the second installment of How's The Stupid Thing Work? in the GR-25 thread.
In the meantime, you could do worse than to put something like 100 Ohms in series with each side of your headphones. Depending on what headphones you have and their sensitivity, you might look to adjust those values up or down after trying it. Yes, you're killing your damping factor, but face it...there's not a lot of mass in a headphone driver. It doesn't need a lot of braking to get it to stop.
It's only 21:30 here, but I'm toast. Heading to bed ASAP.
I'll drag out the schematic and take a look tomorrow or Monday and see what I can see.

Grey
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Old 11th May 2008, 08:31 AM   #676
defect9 is offline defect9  Ireland
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Quote:
Originally posted by GRollins


Give me a day or a week or a month...or something. I've been wearing my farmer hat today (tomatoes, peter peppers, basil) and about a hundred other things, plus I'm trying to find time to put the second installment of How's The Stupid Thing Work? in the GR-25 thread.
In the meantime, you could do worse than to put something like 100 Ohms in series with each side of your headphones. Depending on what headphones you have and their sensitivity, you might look to adjust those values up or down after trying it. Yes, you're killing your damping factor, but face it...there's not a lot of mass in a headphone driver. It doesn't need a lot of braking to get it to stop.
It's only 21:30 here, but I'm toast. Heading to bed ASAP.
I'll drag out the schematic and take a look tomorrow or Monday and see what I can see.

Grey
excellent! I'll begin gathering parts for the regular version, and whenever a headphone-specific one pops out of your brain, I'll be ready for that one as well. About what wattage should the 100ohm resistors be?

If you need to know it, I'm driving 80 ohm headpones at the moment (beyerdynamic DT770Pro). Admittedly, i listen to them more than speakers since I have a flatmate with a different schedule than I.

Thanks again!

-Jared
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Old 11th May 2008, 09:33 AM   #677
EUVL is offline EUVL  Europe
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Default Complementary MOSFETs


While waiting for the Fairchild EU group buy, which is forcast now from Digikey to be 10 weeks (!!! ), we have got a few Toshiba 2SK1530's / 2SJ201's to play with.

The pdf attached plots drain current vs Vgs referenced to bias point, with both values inverted for the P-device to ease comparison. The bias current is 2A for both FETs, Vgs is 2.38V for the N-device, and -2.30V for the P-device. Transconductance at bias is about 4.5 S.

Red line is 2SK1530; light blue crosses are 2SJ201. It was a hell of a job to make the two sets of data visible from one another in excel.

A picture says a thousand words.


Patrick


Attached Files
File Type: pdf toshiba complementary mosfets.pdf (16.1 KB, 762 views)
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Old 12th May 2008, 07:40 AM   #678
alexw88 is offline alexw88  Hong Kong
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I am planning to build a high power version of F5 which uses my existing +/- 35V rail supply, I have add an resistor at the drain pin of the JFET to lower the voltage it see. I ran a simulation and things seem ok. Do you think this schematics would work?

Click the image to open in full size.
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Old 12th May 2008, 09:59 AM   #679
h_a is offline h_a  Europe
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Why wasting voltage with resistors? You could use a cap multiplier for about the same drop with a far better filtered rail as bonus!

Have fun, Hannes
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Old 12th May 2008, 10:45 AM   #680
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Quote:
Originally posted by alexw88
this schematics
~15% more Vgds, MOSFETS at ~140 C, huge heatsinks and possibly exotic Caddock/Isabellenhütte hardware. (R6 typo)

Living la vida loca ?
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