I got my "Yes It Will Drive An F4" boards all populated and ready to install this weekend in my dual mono F4.
I'm posting pics before and after cleaning (99% IsoP with a cheap sonic toothbrush) to see if anyone notices an error before they go into the amp.
I was able to get really good matching of the BC546C pairs using a meticulous matching method (sub 0.1mV!!!) I will share as a "how to" video in the future. I will zip tie the matched pairs together before install.
I'll use DBT for first power up and then variac as a backup mitigation.
Thanks in advance for the keen eyes of the hive diyaudio mind.
I'm posting pics before and after cleaning (99% IsoP with a cheap sonic toothbrush) to see if anyone notices an error before they go into the amp.
I was able to get really good matching of the BC546C pairs using a meticulous matching method (sub 0.1mV!!!) I will share as a "how to" video in the future. I will zip tie the matched pairs together before install.
I'll use DBT for first power up and then variac as a backup mitigation.
Thanks in advance for the keen eyes of the hive diyaudio mind.
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Wow! Fantastic job from a super motivated builder! My highest praise: GOOD ON YA!!!
My F4 awaits! It has been collecting dust for way too long. I still have one old pair of "thirsty," low impedance with high sensitivy, speakers in the house that the F4 pairs gloriously with. Looking forward to putting them all back in the rotation.
Because this: "An input of 1 volt (peak) produces an output of 20 volts (peak)"
I think I'm going to try this: DAC->YICADAF4'd F4.
Then this: DAC->H2 preamp ( unity ), YICADAF4'd F4.
Because this: "An input of 1 volt (peak) produces an output of 20 volts (peak)"
I think I'm going to try this: DAC->YICADAF4'd F4.
Then this: DAC->H2 preamp ( unity ), YICADAF4'd F4.
In #47 photos, diodes D2 and D3 have (abutted end) == (anode) and (flywire end) == (cathode). They are electrically correct, anode of diode goes to "A" terminal on PCB precisely as required, and I expect they will operate flawlessly. However, the topside silkscreen calls for the opposite stuffing: cathode abutted. This won't make any difference except in debugging (planning where to attach probe clips), since your flywire nodes are not what the schematic and its designer expect. If you don't ever need to debug anything in the vicinity of the diodes, it's a complete dont-care.
Also for those with crippling OCD, leg #1 of transistor Q9 has a tiny speck of unremoved flux (white PCB). A wooden toothpick and some uttered grunts ought to prise that off pretty fast.
Also for those with crippling OCD, leg #1 of transistor Q9 has a tiny speck of unremoved flux (white PCB). A wooden toothpick and some uttered grunts ought to prise that off pretty fast.
No advantage in matching /coupling the current mirror, Q6+Q8? I've run across folks in the past recommending such a thing. When you have a hammer (transistor tester), everything looks like a nail (pile of un-characterized transistors). I guess the emitter degeneration there makes it moot.. (??)
Hey Dan!
I'll share how I do first power up nowadays...I test the boards attached to heatsinks but before installing in the chassis. I just use a lab power supply linking two channels for bipolar output. You can set a current limit and the bring up the voltage slowly. Works great if there's any troubleshooting and you can set bias (at least close) before installing in chassis. From pictures I've seen of your bench, it looks like you have a lab supply capable of doing this.
We have music folks!!!
Just playing on my cheap test speakers right now so I can't say how it sounds, but happily playing glorious music.
Thank you @Mark Johnson !!!!
Really fun project!
Just playing on my cheap test speakers right now so I can't say how it sounds, but happily playing glorious music.
Thank you @Mark Johnson !!!!
Really fun project!
I've now got my F4 with "Yes It Will Drive An F4" IPS hooked up to my Aerial Acoustics Model 9's and it's gooood....it's REAL good! These are 50W-600W speakers with 4 ohm nominal impedance (3.2 ohm minimum) and the F4 has totally come alive with the YIWDAF4. I'm getting slamming bass and crisp highs. Right now listening to Meute Live in Paris and the horns and drums are singing like I'm right there at the concert. I'm driving the F4 with the Iron Pumpkin, which had been previously very quiet without an IPS. I had reverted at the time to an old X350.5, which just kicked butt, but this 25WPC F4 is giving me the same swing and slam now!
Love this folks! The "Yes It Will Drive An F4" input is a real winner. Give it a try. You won't be disappointed. Yeeehaaaw.
I gotta stop typing, get up on my feet, and throw my hands in the air!!!
Love this folks! The "Yes It Will Drive An F4" input is a real winner. Give it a try. You won't be disappointed. Yeeehaaaw.
I gotta stop typing, get up on my feet, and throw my hands in the air!!!
It IS driving an F4!!! Fantastic!!!
Outstanding work @birdbox !! Besides spectacular craftsmanship, you win the Speedy Gonzales award: 39 days from (Gerber files unveiled) to (working amplifier with swing and slam). Wowzers.
Good on ya!
Good on ya!