SUPERKEEWOOT. 😀
John, it'll be healthy for us if you finish it fast. Hard to wait. 😉
Total quiescent Current: 130mA~150mA, including VAS current.
(from notes, depending on how the bias is set, and DC rail variation)
Sample measurement:
Total quiescent current 137mA
Front end: 15.5mA
DC supply: 35.1V
Test conditions: 35V-37.5V DC rail voltage.
Total current measured directly w. meter in series
Front end current measured across 10R resistor which is in series w. the 1N4004 diode, ~15mA.
I can adjust the AC voltage roughly, +/- 1~2V using a Variac (not exactly, I am using a monster of a Superior-Electric Variac bought for scrap prices on ebay). The DC volatage can be adjusted within +/-0.1 thanks to my power supply from MrEvil's thread, but it does drift w. temps.
Total bias (quiescent) current should probably be measured only when the main heatsinks reach stable temperature.
If someone can suggest other test conditions, I will be happy to take some measurements.
yes they are 😉 got it from Mr Daniel
Oops sorry
Ok, by your request I'll do it faster as I can
I just remember that my father have one big variac too, I will use it hehe 😀
John's PeeCeeBee's got something special about it... I dunno wot but looks like it's made of edible sweet solids LOL...
Lookin' forward.
Lookin' forward.
John's PeeCeeBee's got something special about it... I dunno wot but looks like it's made of edible sweet solids LOL...
Lookin' forward.
thanks shan
I was wondering if it's me or someone else whose dual FET boards are gonna be shown here first.
Better make it before September comes coz I'm gonna get myself a bunch of them by then... hohoho....
Better make it before September comes coz I'm gonna get myself a bunch of them by then... hohoho....
Seems you're gonna be the first one with the double barreled gun...
I hope you are using 2K2/100R feedback network. If 1K/47R is used then the amp may oscillate without some bandlimiting.
I hope you are using 2K2/100R feedback network. If 1K/47R is used then the amp may oscillate without some bandlimiting.
Hi shaan, for my personnal cultur could you explain advantages to use 1k/47R with zobel over 2k2/100R alone?
Marc
Hi Marc.
Personally, I don't see an advantage of the 1K/47R over 2K2/100R.
Both can be made stable, but it is likely that the 1K/47R will introduce oscillation unless some kind of compensation is used. And I am an old hater of capacitors in VAS stage, seems to be another non-linear function added in the equation. See the simulation attachments. The 1K/47R almost doubles the bandwidth. But also notice the peaking. Meaning we need some more small capacitors somewhere in the signal path.
In my experience the 2K2/100R config has always been stable without any extra compensation other than the purely resistive band-limiting induced by the higher value feedback resistor (something called 'autocompensation' if I am not wrong). I feel this is the better way to make it stable.
THD-wise, I doubt there will be any audible difference.
shaan
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Shaan,
Seems you're gonna be the first one with the double barreled gun...
I hope you are using 2K2/100R feedback network. If 1K/47R is used then the amp may oscillate without some bandlimiting.
thanks for your secret formula, it is now singing loud 🙂
I guess this is what I need, the older brother need to some modification
I've just test it with little speaker & lower voltage but I change the gain to 30dB 😀
not oscillated (lucky me, with 1K5//47R resistor)
DC offset is 11.5mV (will fix it latter)
I have a tips how to set zero offset, you see the two bended jumper right...
that is parallel with 18k resistor I use there, touch it with your finger & you now which one 18k's resistor need to be lowered value...
The bad news is the older brother have a short Latfet because I connect to wrong rails 😡,
need to repair it too with your secret formula 😉
Now I need to finish another channel, I feel so excited...
Attachments
dear what secret formulaShaan,
thanks for your secret formula, it is now singing loud 🙂
I guess this is what I need, the older brother need to some modification
I've just test it with little speaker & lower voltage but I change the gain to 30dB 😀
not oscillated (lucky me, with 1K5//47R resistor)
DC offset is 11.5mV (will fix it latter)
I have a tips how to set zero offset, you see the two bended jumper right...
that is parallel with 18k resistor I use there, touch it with your finger & you now which one 18k's resistor need to be lowered value...
The bad news is the older brother have a short Latfet because I connect to wrong rails 😡,
need to repair it too with your secret formula 😉
Now I need to finish another channel, I feel so excited...
Agh... what innovative speaker design John! 
Congrats. You are the first to build the dual FET PeeCeeBee made of edible sweet solids.
Please upload the pdfs of layout, silkscreen and mask if you think we should eat... uuh.. build it too.
Again, what innovative speakers John, quite inventional haha...
Congrats. You are the first to build the dual FET PeeCeeBee made of edible sweet solids.
Please upload the pdfs of layout, silkscreen and mask if you think we should eat... uuh.. build it too.
Again, what innovative speakers John, quite inventional haha...
@shaan, Good day, is it possible to change FET to a transistor(C5200/A1943)? It's hard to find FET in my location. Thanks..
Check out the thread here, despite its title the thread has produced various configurations including BJT options for outputs. It is based on the same basic structure as the original VSSA and PeeCeeBeee.