Amp Camp Amp - ACA

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.
 
Official Court Jester
Joined 2003
Paid Member
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.

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
 
diyAudio Editor
Joined 2001
Paid Member
But is this a teaching tool or is it an amp you could listen to for a few years? I would love to know from some of the builders how it sounds into full range drivers (reviews).
I would like to know if it could beat my current class-D demo board for an ADAU1592 with diy power supply to drive my Fostex full range speakers (all subjective I know).

One thing that I think would encourage more people to "jump in the pool", If the parts to populate the PCB are provided. To my everlasting shame I have purchased some
PCB’s I have never populated, and will most likely never do so. However I am happy to say that I have built every kit I have ever purchased (mostly headphone amps)
where the parts to populate the PCB were provided. This is what Glass Jar Audio does.
Leve

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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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!

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. :D
 
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:

Here is an example of a JFET follower whose characteristic is mostly “pentode-like”. The upper curve reflects the distortion at V+ voltage near the device rating, and the lower curve shows the distortion cancellation available by searching for the “sweet spot” at a lower supply voltage. You can see that at 1 volt, the distortion has been reduced by about 85%.
 
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