darian said:
This has been discussed before. As I said in the article, "The
topology is familiar." Complementary feedback pairs, AKA
Conjugate complementaries, are elementary and go way back.
My first exposure was from the Motorola app notes, late 60's -early 70's.
Why did no one give a damn about the Profet?
Maybe they did. Maybe they won't give a damn about the F5.
Finally got a copy of the May AudioXpress mag. Damn, I'm really glad I picked this up. it's way easier than trying to pick the information out of the thread, and all the explanation of "why" helps me out a lot, especially the analogy of FET devices (which I could never understand).
I'm definitely building this one.
one question though, if I wanted to add a headphone out (for late night listening), what are some good ways to do it?
-Jared
I'm definitely building this one.
one question though, if I wanted to add a headphone out (for late night listening), what are some good ways to do it?
-Jared
GRollins said:
okay being a bit of a newb to this, having only built one kit and one "from schematic" amp, where would be the best place to put these resistors? All the books I've gotten dont really delve far enough into audio electronics for me to be certain where to put them.
I definitely don't have the know-how to pull off designing a mini version yet.
seventenths said: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
Poor Kid!!..Hopefully delinquency wont follow...
mrothacher said:
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.
seventenths said: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.
defect9 said:
GRollins said:
defect9 said:
Variac said:
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
GRollins said:
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
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
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
