Babowana said:
2SK170BL,
2SJ74V,
all Toshiba, no copy, real bought in Korea
I have some you need?
I can send you 4x each . . . no jok tho drunk tonight . . .
Free . . . give me youe adress . . .
MANY THANKS for your GENEROSITY!!! The little jewels arrived today looking famished ,hungry for those ZV5 milliamps. A toast to you (Cuervo Black Anejo)!!
Hello all, just deffering finishing the other channel of the JFET ZV5 so I can finish the Krell KSA-50 Clone that has been awaiting a nice chassis... pretty complex compared to the ZV5, but sounds very nice so far.
Anyway, got an embarrassing question to ask all you smart people...seems I remember reading the ability to sub a few different types of transistors in the ZV5 circuit...
I have a number of 2SA1943/2SC5200 (confirmed non fake!!) Toshibas left over from the Krell Clone and wonder if I could sub in a pair instead in a JFET ZV5 circuit instead of the IRF9240/240...
Please go easy on me, as I am a bit of a tyro on these transistors "types"... and very thenthitive too.
Anyway, got an embarrassing question to ask all you smart people...seems I remember reading the ability to sub a few different types of transistors in the ZV5 circuit...
I have a number of 2SA1943/2SC5200 (confirmed non fake!!) Toshibas left over from the Krell Clone and wonder if I could sub in a pair instead in a JFET ZV5 circuit instead of the IRF9240/240...
Please go easy on me, as I am a bit of a tyro on these transistors "types"... and very thenthitive too.
The 2SA1943 is a transistor, not a mosfet.
Transistors take a lot of drive current through the gate, unlike a mosfet, which has very high gate resistance.
This is one characteristic of mosfets that Nelson exploited to make 2 stage amps with respectable power output, decent distortion measurements, and spectacular sound.
I doubt that there is enough drive current going through the jfets of the babozen 5 to drive a great big transistor. There is a formula to calculate how much drive current you will need, but I don't know what it is, and I am too lazy to go look it up.
Maybe someone will help us out here.....
JJ
Transistors take a lot of drive current through the gate, unlike a mosfet, which has very high gate resistance.
This is one characteristic of mosfets that Nelson exploited to make 2 stage amps with respectable power output, decent distortion measurements, and spectacular sound.
I doubt that there is enough drive current going through the jfets of the babozen 5 to drive a great big transistor. There is a formula to calculate how much drive current you will need, but I don't know what it is, and I am too lazy to go look it up.
Maybe someone will help us out here.....
JJ
Cgd for the 240/9240 is something like 85/125pF at a Vds of 20V, suppose 250pF for the pair.
That requires 1mA for each 4 volts of slewrate, 5mA gives a SR figure of 20V/uS.
Closing the JFET pushes all 5mA into/out the base of a 1943/5200, with the hFe of 100 as i mentioned in the ksa50 thread you'll have 1/2 an amp of output current, only 1W/8 continuous (in theory)
You'd have to bump up the current gain by adding a driver stage that would add another 100 hFe, makes 50 Amps output current.
But then it's no longer Zennish, no ?
That requires 1mA for each 4 volts of slewrate, 5mA gives a SR figure of 20V/uS.
Closing the JFET pushes all 5mA into/out the base of a 1943/5200, with the hFe of 100 as i mentioned in the ksa50 thread you'll have 1/2 an amp of output current, only 1W/8 continuous (in theory)
You'd have to bump up the current gain by adding a driver stage that would add another 100 hFe, makes 50 Amps output current.
But then it's no longer Zennish, no ?
Wow...pretty complicated stuff...I got a bit tripped up on the two output types "interchangability" after I read up on the JLH (transistor output device) morphing into the PLH (Mosfet output device) amp at passdiy.com.
I just thought I would be able to basically use an output board layout like the KSA-50 - 2.2 ohm base resistors and .649 ohm emitter resistors - to the JFET Babozen front end - shows how much (little) I know....
Like I said - have a few 2SA1943/2SC5200 pairs left over and was just a bit too lazy to buy a few more IRFP9240/240.
Don't know what my issue was, as they are easily available and relatively cheap at tech-diy.com...
Cool. Thanks for the answer...
I just thought I would be able to basically use an output board layout like the KSA-50 - 2.2 ohm base resistors and .649 ohm emitter resistors - to the JFET Babozen front end - shows how much (little) I know....
Like I said - have a few 2SA1943/2SC5200 pairs left over and was just a bit too lazy to buy a few more IRFP9240/240.
Don't know what my issue was, as they are easily available and relatively cheap at tech-diy.com...
Cool. Thanks for the answer...
john65b said:
It's actually a bit more complicated, and it also depends on the operating mode of the device, but examples better be simple.
It was posted that it took even a biggy such as Borbely to the 90s to get it completely right, same experience i got with a couple of pro audio stiffs on this side.
A MOSFET behaves like a capacitor, it's driven by charging/decharging the capacitance at the gate.
The speed at which the capacitor's voltage increases depends on the current level it's loaded with, for a given capacitor size.
Capacitance is Farad, F is A*s/V , amps times second divided voltage.
Or : A divided by V/s, same-same as current divided by the required slew rate.
A bipolar device also has capacitances from base to collector and emitter, but they are generally much smaller, a MOSFET is somewhat comparable with a very high hFe darlington transistor.
JackinNJ is a good source for matched devices to go in parallel, your Zenl only has a single complementary pair, any source will do.
(in a couple of years, your head will be filled with amp tech, and you'll have forgotten all of your beloved LandRover stuff)
Sorry - didn't mean to offend our fine friends from the UK on my Rover/British bash. I actually am quite fond of my 2002 Disco II, even with all of its idiosyncrasies...the thing is a rock...I cannot complain of its gas consumption as I work for a Major Oil Company - so it like taking $$ from one pocket and putting it into the other...
Sandy -> Thanks for those sinks - I have the Krell to finish and then the Aleph 60...I just knocked out a single channel of the BABOZEN with a bit a spare time I had waiting for a chassis to arrive from China (90+ days, but relatively cheap)
I am quite impressed with the BABOZEN's simplicity and sound quality with so few parts compared to the Aleph/Krell.
I can't wait to knock out the second channel and have a free weekend to determine which sounds best on my Maggie MGIIIa's (I don't listen very loud, so should be some what an even comparison between all).
Sandy -> Thanks for those sinks - I have the Krell to finish and then the Aleph 60...I just knocked out a single channel of the BABOZEN with a bit a spare time I had waiting for a chassis to arrive from China (90+ days, but relatively cheap)
I am quite impressed with the BABOZEN's simplicity and sound quality with so few parts compared to the Aleph/Krell.
I can't wait to knock out the second channel and have a free weekend to determine which sounds best on my Maggie MGIIIa's (I don't listen very loud, so should be some what an even comparison between all).
Hey all, I just ran an interesting test on my BZV5...I got a little bored today and decided to build a +/-20VDC power supply out of two Laptop SMPS. They are HP branded and both 20VDC - 0 and 3.2A. I connected two of them to get the dual rails.
I connected the newly made PS onto a single channel and it sounded very nice. No hum/hiss that I could hear. I had the bias cranked to 950mv across the .47 ohm resistor, so 2A/fet, 40Watts/fet, so 80 watts dissipated to the sinks.
Not bad. No heavy transformers or caps. No power on/off thump either. Seems to have plenty of power (well, sorta).
I know I am really torturing those power supplies, but this is most likely nothing compared to a laptop load...
I know these laptop PS aren't exactly cheap, but I have quite a few and they are just sitting around collecting dust...so what the hell...
Anyone tried this yet - running a Class A amp off SMPS??
Am I koo-koo for cocoa-puffs?
I connected the newly made PS onto a single channel and it sounded very nice. No hum/hiss that I could hear. I had the bias cranked to 950mv across the .47 ohm resistor, so 2A/fet, 40Watts/fet, so 80 watts dissipated to the sinks.
Not bad. No heavy transformers or caps. No power on/off thump either. Seems to have plenty of power (well, sorta).
I know I am really torturing those power supplies, but this is most likely nothing compared to a laptop load...
I know these laptop PS aren't exactly cheap, but I have quite a few and they are just sitting around collecting dust...so what the hell...
Anyone tried this yet - running a Class A amp off SMPS??
Am I koo-koo for cocoa-puffs?
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