Hi there, I just tested the amplifier and it is a lot of distortion. Could be my mistake or the difference in the JFET? I received the K370 instead of the k170
Yeah, a $300 SMPS. ROFL. I'll bet the standard Meanwell with, or without, Mark's filter board is every bit as good or better. Some people just like to spend money. Wait... did I just say that?
There's no linear power supply here to try with the amp camp mini. Unfortunately.
But I've run it with the suggested power supply and with the power supply from the original amp camp amp (which puts out a bit more current). The folks who heard the two different power supplies liked the original amp camp power supply.
And both power supplies sounded better with Mark's filter. The mini really sounds great and the updated power makes it even better.
But I've run it with the suggested power supply and with the power supply from the original amp camp amp (which puts out a bit more current). The folks who heard the two different power supplies liked the original amp camp power supply.
And both power supplies sounded better with Mark's filter. The mini really sounds great and the updated power makes it even better.
I had two hours of free time tonight giving me chance to sit down and listen to both ACA Mini amps I have. Both amps use the “Almost Clone” boards… artwork done by Mark Johnson using the original circuit designed by Nelson Pass. The first amp, the red “prototype” amp has matched Fairchild FQP3N30/FQP3P20 installed in it, while the green “REV A” amp has the matched Harris 520/9520. Both amps sound amazing, but I’m hearing a clear difference between the two. I made some notes while listening so I can share my findings.
I’m going to kill the punch line here… I prefer the amp with the Fairchilds by a wide margin, with or without the jumper in place. The reason I prefer this amp is that I find the midrange more clear and detailed, making instruments come into focus. This makes it easy to the hear the delicate sound of a finger pressing against the string of a guitar. Instruments sound more full and dimensional as well. With this amp though, the highs are a bit rolled off (which I don’t mind at all). The bass may be a bit rolled off as well not going quite as deep.
Here's the funny thing…with the “Fairchild” amp I prefer the jumper in, but with the “Harris” amp I prefer the jumper out. It gets even better…with the Fairchild amp I prefer the absolute phase non-inverted, while the Harris amp I prefer the sound with the phase inverted meaning + and – switched at the speaker terminals. Go figure.
I’ve sent sets of the Fairchild FQP’s to three people and I believe @rhthatcher is going to try them as well. I'm more than curios to know their findings.
I’m going to kill the punch line here… I prefer the amp with the Fairchilds by a wide margin, with or without the jumper in place. The reason I prefer this amp is that I find the midrange more clear and detailed, making instruments come into focus. This makes it easy to the hear the delicate sound of a finger pressing against the string of a guitar. Instruments sound more full and dimensional as well. With this amp though, the highs are a bit rolled off (which I don’t mind at all). The bass may be a bit rolled off as well not going quite as deep.
Here's the funny thing…with the “Fairchild” amp I prefer the jumper in, but with the “Harris” amp I prefer the jumper out. It gets even better…with the Fairchild amp I prefer the absolute phase non-inverted, while the Harris amp I prefer the sound with the phase inverted meaning + and – switched at the speaker terminals. Go figure.
I’ve sent sets of the Fairchild FQP’s to three people and I believe @rhthatcher is going to try them as well. I'm more than curios to know their findings.
Kevin's questions is very important.
'Sounds' but no music is exactly what the amp will sound like when music is being played (loudly) but the bias supply is OFF. Double check your bias and offset voltages and that you have close to 12V DC at the gates of Q1/Q2.