Kit build: stereo amplifier.

[@canaduino]

About R8 and R9: The 100k were added at a later stage to achieve a higher gain. The kit was originally designed with the 33k and later updated without changing the PCB. Updating the schematic is much easier than a batch of 500 PCBs. The reason for the extra parts is that the parts for the kits were already picked for a different stage of the development, and parts replaced at a later stage were just added without removing the replaced parts from the kit. Nothing wrong with some extra parts, right?

[@pileofstuff]

Thanks for the clarification!

[@stephendredge6077]

According to the schematic C8 and C9 decouple the input bias network to the positive rail instead of ground. This must be a mistake. It will couple noise from the power supply into the 2030 input. Is error on the PCB as well?

[@markfergerson2145]

(third edit) They’re beefy electrolytics, so they shouldn’t pass much audible noise. Looks to me they’re there to hold that reference point solid.

[@stephendredge6077]

@@markfergerson2145 C1, C2, C10 and C11 ensure the power rail has a sufficiently low impedance at AC to allow for resistance and inductance in the power supply and cable. The capacitors will reduce but not eliminate power supply noise and ripple. The R10,R1 junction is set to be half the power rail voltage so the 2030 output is also half rail. AC wise it should be ground. C8 should therefore go from this junction to ground.

[@canaduino]

@@stephendredge6077You found the easter egg. C8 and C9 should better be connected to GND to avoid noise from the power supply. We will change this with the next revision.

[@johncoops6897]

15:15 - thermal paste has left the chat 😂 - you should always add a thermal interface for components that require a heatsink.

[@pileofstuff]

I can always sneak some in there when i ge around to building a cabinet for this .

[@johncoops6897]

@@pileofstuff - BEWARE... also check the width of "ribs" on heatsink where TO-xxx package bolts down. I just repaired some electronic loads where the sides of the device package were tight against the ribs, so the screw didn't pull it down 100% flat onto the heatsink 😢

[@canaduino]

@@johncoops6897 The heat sinks in the kit fit the ICs just perfectly.

[@johncoops6897]

@@canaduino - My sarcasm detector was flashing, but it's always difficult to know when reading KZbin replies 😉 . The heatsinks that I just fixed looked like they fitted the TO-xxx devices perfectly, however there was actually a tiny sliver of light visible on one side of the device where it had not pulled down properly. It was the exact same design of heatsink as shown in this video. I actually ground a small chamfer on the rear side edges of the device, and left the HS alone.

[@canaduino]

​@@johncoops6897 The sarcasm detector! Let's make a kit 🙂

[@lorisrobots]

Great kit build - I am learning some nice techniques from watching you do these kits. Thanks for posting!

[@DustinWatts]

Not even December! What a treat :D

[@Kae6502]

4:25 Yes! Well done! :D That shot made my day. Cheers! 🍻

[@canaduino]

V1.2 with updated PCB and schematics is already in the works. Prototype PCBs have already arrived but still need to be assembled and tested. Watch for the version number change on the product page (currently V1.1). ETA March 8-12.

[@frankowalker4662]

I knew it would be a good build. I love analog amplifiers.

[@brettkaufman2299]

I like your pointer stick! Also your channel. Thanks!

[@Ernzt8]

Maybe you can use the valve caps people keep sending you as keys

[@jerril42]

That was fun. I noticed the cool overhead shot from the swing cam and zoom during the resistor installation. Some fancy editing there. Nice kit, I've been looking at that amp, but I don't have a need for one right now. Thanks for the morning entertainment. Take care.

[@onecircuit-as]

Good build, very relaxing! 👍😀

[@mr.makeit4037]

Excellent job!

[@erikburman530]

What? No thermal paste?

[@iceberg789]

looks neatly designed, but the tone control is passive only. i would have added a dual transistor preamp arrangement, which sounds a lot better. also the input coupling caps are 220nF only. pl upgrade then to 1uF box type non polar ones. no compromise.

[@canaduino]

Come on! This is a kit for solder-ironists to fight boring boredom on a winter weekend. The kit was never meant to compete with a NAD - hence the $15 price tag and the compromises.

[@canaduino]

The 220nF caps deliver 15Hz cut-off at 3dB. 1µF MKT caps would lower that to 3Hz and increase the price by 2 bucks. For what? If you have speakers that let you feel a difference between 3Hz and 15Hz, you would pump north of 1000W into them, but not 15W.

[@Multi-Skill-Bill]

That is a nice looking little kit. You made short work of it. How do you like that PCB holder? I just got one and haven't used it yet.

[@pileofstuff]

I spent a few months trying out a bunch of different board holders. This one turned out to be the one I kept coming back to after trying each of the others.

[@Multi-Skill-Bill]

@@pileofstuff Cool, I cant wait to try mine out. Kinda in the middle of a bench remodel :)

[@quandiy5164]

I think your 3.5mm cable is fine. I didn't see you solder the ground pin on the input jack (not sure if it was soldered off camera) if it wasn't soldered, that can cause the humming when you move the input cable.

[@pileofstuff]

I tested this cable with another powered speaker - it's definitely the cable.

[@timidater4803]

Where did you get your board holder? Thanks keep rockin!

[@pileofstuff]

Got it from ebay several years ago. Here's one of the many sellers: pileofstuff.ca/r/oan0y Feel free to use the words in the listing title to search fo ra less expensive one (or one with cheaper shipping to your country)

[@timidater4803]

Thanks man it's time to ramp up my guitar pedal builds!

[@mariushmedias]

The heatsinks are not big enough to keep these cool if running at high output power. I would have liked to see bigger rings to allow for easier soldering on such project, seems like there's space to allow for that, would make soldering with shitty irons easier. Also, kind of a shame to see carbon film resistors, would have been nice to see better metal film resistors.. they're pennies when you buy boxes of 1000-5000 so you're not saving much by going with carbon film resistors. Would have been cool to have a sort of lead forming tool especially as it looks all resistor are same size, could easily 3d print something or have a bit of circuit board with half through holes on the edges to bend leads around board. I didn't see the mating connectors for the speaker headers put on the board, and those don't look like standard connectors ... and even if mating connectors are included do those need crimping the wires? Maybe use bog standard RCA or connectors where you screw wires into instead in a future revision?

[@danman32]

I'm not keen on how R11 was mounted. Not nice an flat.

[@pileofstuff]

Yeah, I didn't notice it until after I had trimmed the leads. Fortunately it has no impact on the function of the circuit.

[@TheUnofficialMaker]

aww, no smoke and bubbling plastic lol

[@EsotericArctos]

I am not sure I agree that modern components are more resilient. Sure, very very early (like 60's) transistors were fragile, but 70's/80's electronic components seem a lot more tolerant and robust than todays ones. It's like we have gone backwards because it's about making things as cheaply as possible now instead of making quality

[@HazeAnderson]

Maybe you could do a kit by starting with the physically largest, highest profile and most likely to get damaged components instead 😄as a challenge 😄for SCIENCE! 😄

[@pileofstuff]

😳 You really want to see me struggle! 🤣

[@erikburman530]

It's not good form to leave it up to the kit builder to figure out how to resolve discrepancies. If the circuit has been updated it would have been very easy to include a notice explaining the situation. -2 points. Unforced error!