I can understand why bf862 sounds good but not sure why changing the bipolar would make much difference. Or are you saying you used those parts because that is what you had on hand?
2n4401 sounds clearly better to me than bc550c, more detail especially. But then again it depends on the rest of your system.
I ve experiment with bjt s in this position also with salas shunt and i does influence the sound to a certain degree. it is a reference for the current setting after all.
I ve experiment with bjt s in this position also with salas shunt and i does influence the sound to a certain degree. it is a reference for the current setting after all.
are you talking about amp made by Camp Amp schematic ?
that (sole ) bjt is bootstrapped with 1KuF ;
there is no way you can hear difference between ZTX , BC , 2N or even BD139 in that position
toss it , and use pot instead , all you'll have is just different biasing ....... while that 1KuF is there , it will be hardly any change in sound
Q3 is there simply to maintain 0V65 across R1+R3
yes that is the amp, CLC psu though.
i swear to god i hear a difference.🙂
but now you hust put a little doubt in my head...
i swear to god i hear a difference.🙂
but now you hust put a little doubt in my head...
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if you're not setting same bias (and that is hardly , without pot in that area ) , then you'll hear difference ........
again - induced by bias amount change , not difference in bjt type
again - induced by bias amount change , not difference in bjt type
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Many good points here. I've listened to it a bit, but now that amp camp is over :
-I have to work a lot due to neglecting my real job preparing for the event.
- We organizers gave up our PCB's so more people could participate (they were begging to come! ). Then the amps all went home with people. I did listen to them on various systems though, and they do have that Pass sweet sound for sure. They seemed happier with full range drivers.
And yes we are not only ordering boards, once we clear up the PCB/schematic discrepancy, but we'll have it bundled with parts so it can be built up easily and quickly. We've already proven it can be built in half a day. Ours took a bit longer for most people due to the chassis requiring cleaning and polishing.
There are going to be a lot of happy newbies making amps.
The amazing thing to me is how easy and cheap it is to use the SMPS. Of course lots of people could propose such a thing, but Papa is in the position to bless the concept, and make it work and we all then believe him. And sure it seems obvious now, but great ideas always do after the fact!
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you have a good point that bias should effect the sound...but that much? i dont know...
2n4401: 0.55V
bc550c: 0.65V
can a lesser bias sound better?
difference between 0V55 and 0V65 is bias difference between 478mA and 565mA ..... so , around 16% increase
which one will be better to your ears ......... well - those are your ears
which one will be better to your ears ......... well - those are your ears
ok but...can an ugly old turkey (post 51) even recognize sound? 🙂
no seriously i might just be crazy but i prefer not to admit it publicly 😛
i ll begin by building another channel first, that might help my cause...
P.S. isnt bias around 1 A...?
no seriously i might just be crazy but i prefer not to admit it publicly 😛
i ll begin by building another channel first, that might help my cause...
P.S. isnt bias around 1 A...?
Yeah I was suggesting this years ago now, and everyone laughed at the suggestion like I was on drugs or something. I just might have convinced Nelson though. 😀
I've been running an aleph mini on some apexjr smps for a few years. Sound was much improved by adding some 1000uf caps after the smps.
For a simple, great sounding, set of full rangers the Betsy K in a 1 1/2 cubic foot box is a good choice.
(made in america, just like the amps. And cheaper than fostex too.)
(made in america, just like the amps. And cheaper than fostex too.)
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Will SMPS becomes unstable with larger power supply filter caps? there's only a 10uF in the diagram.
Thats certainly a possibility. These were modules (not encased) for which the datasheet was available. There was a mention of additional RC filtering, but I can't remember the values they used. I figured 1000uF was safe, and it's turned out fine.
good one
I put a 15,000uF cap on the SMPS that came with my Tripath amp to try and get rid of the hiss. It destroyed it instantly. It's not serviceable. Not all SMPSs can take high capacitance on there output.
Filtering for the jfet could easily be done with an RC network (maybe 2K and 1,000uF). There is lots of voltage to spare. It could be used to find a “Sweet Spot” in the Pass article “The Sweet Spot” an example is provided:
Filtering for the jfet could easily be done with an RC network (maybe 2K and 1,000uF). There is lots of voltage to spare. It could be used to find a “Sweet Spot” in the Pass article “The Sweet Spot” an example is provided:
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