Err NO, ZTX450 is an NPN transistor. The ZTX550 is a PNP transistor...
What IS of special importance is VBE(on) versus collector current. Since that's the mechanism which regulates the class A bias current.
Another ACA has successfully been built thanks to this community and all the resources generated by you all. I completed my first amp last night, my first serious project ever. After replacing a cooked a power jack, the center pin has collapsed due to excessive heat, and rehabilitating a deformed RCA jack, also suffering from my heavy handed soldering, I balanced the DC and hooked it up to a RPi HiFiBerry DAC and pair of Zaph ZA5.3.
I'm super happy with the results and the performance exceeds my expectations. I get a definite expansion in the mids with so much more detail. Since the ZA5.3 are not particularly efficient, I was a little concerned that I would be building speakers next, but the ACA seems to effortlessly drive them at the same input volume range as my old, ailing Denon receiver. That receiver never gave the ZA5.3 a fair shake and had become unbearably exhausting to listen to.
Knowing you all are here to answer questions was part of the draw to take this on. Thanks to @Mark Johnson, @Skylar88, and @Allan for responding to my noobie questions. Still so much to learn so thank you for your ongoing patience.
Moving on to the B1K next, an active sub, then?
I'm super happy with the results and the performance exceeds my expectations. I get a definite expansion in the mids with so much more detail. Since the ZA5.3 are not particularly efficient, I was a little concerned that I would be building speakers next, but the ACA seems to effortlessly drive them at the same input volume range as my old, ailing Denon receiver. That receiver never gave the ZA5.3 a fair shake and had become unbearably exhausting to listen to.
Knowing you all are here to answer questions was part of the draw to take this on. Thanks to @Mark Johnson, @Skylar88, and @Allan for responding to my noobie questions. Still so much to learn so thank you for your ongoing patience.
Moving on to the B1K next, an active sub, then?
Attachments
There have been inquiries about the ACA kit. The complete kit is out of stock due to lack of chassis’
More should arrive within a couple weeks.
The parts kit is in stock now!, as well as the PSU.
https://diyaudiostore.com/collections/amp-camp-amp/products/amp-camp-amp-parts-kit-onlyIf you’re in the U.S.A. Where shipping is cheap, you might want to order it to get started.
More should arrive within a couple weeks.
The parts kit is in stock now!, as well as the PSU.
https://diyaudiostore.com/collections/amp-camp-amp/products/amp-camp-amp-parts-kit-onlyIf you’re in the U.S.A. Where shipping is cheap, you might want to order it to get started.
Last edited:
And yet another one, different from my previous stock build because I put it in a 4U chassis and am using IRFP150 MOSFETs at Q1/Q2, a "backwards" BC550 instead of the ZTX450, and a 15000 µF cap at C1. I'm loving hearing Wilco's Yankee Hotel Foxtrot right now after finding Elvis Costello's King of America too strident to bear. There's a tangible heft to the sound that's real nice. Call me crazy, but I like the overall sound better than my long-gone F6 and recent F5 and maybe even the F4.
@rubah.ganteng what value are those 3w resistor.? They seems to be 68k and 4.7k but should be 0.68ohm and 0.47ohm
What would have happened if these were used? I'm no where near as tech savoy as the rest of you guys. Trying to learn.
THANKS!!!
THANKS!!!
If those large value resistors were used, the amp would have an excessively large output impedance. Basically it wouldn't work.
So, I either didn't get, or managed to lose, one of the ZTX450 transistors in ACA kit. I had trouble finding one but our awesome DIY Audio Store got me fixed up with 2 new ones. I do have one, probably silly, question. Do I need to worry about those transistors matching? I don't think so based on my 30 years ago electronic training ( that I'm working very hard to relearn.) I just wanted to be certain before I screwed something up!
Thanks.
Joe
Thanks.
Joe
Hi, I have two ACA’s run in mono. One or both of them have been making a clicking / popping sound randomly( sound is coming from inside the amp not speakers) Hard to describe the sound. Any idea what the cause could be?
Were they just completed or have they been running for a while?
Could be bad solder joint or joints.
Edit: Whoops, I was thinking clicking from the speakers, then bad solder joints. From inside the amp, maybe caused by heat induced expansion of a part?
Could be bad solder joint or joints.
Edit: Whoops, I was thinking clicking from the speakers, then bad solder joints. From inside the amp, maybe caused by heat induced expansion of a part?
Last edited: