Aite. So, the speaker I chose was too deep for the enclosure I bought.
Not by much, mind you. I only needed about a quarter inch.
Well...the back panel doesn't *need* to be 9mm. Problem is, I didn't feel great about spanning the entire back of the cabinet with 3mm plywood. I wanted something a bit stronger.
So, I cut a piece of 3mm carbon fiber, created a couple of 1/4" stand-offs, and viola.
Then comes the needing to make it match the rest of the cabinet. So, my first try with applying tweed.
For standby switches almost everyone uses regular 250V ones. Some “protect it” with a cap in parallel. Having one is not needed thought. Plenty of amps were built without one and were perfectly fine, and it has been demonstrated that tubes amps fare better without one anyway. Just have a mute switch for the functionality and you’ll be just fine.
Inrush current isn’t a problem with a tube rectifier as it slows current while warming up, but you’re limited to smaller value caps on the first filtering stage.
Inrush current isn’t a problem with a tube rectifier as it slows current while warming up, but you’re limited to smaller value caps on the first filtering stage.
The only extra little mod I've added is a pair of protection diodes on the tube rectifier. These are there just to "pre-rectify" the B+ in case of tube failure in the future.
A traditional standby wouldn't really help with inrush even with solid state rectification: switching the B+ on will lead to inrush regardless.
Though it makes sense if you've got a resistor of sufficient size across the terminals. Typically I see an NTC thermistor take this role in SS designs.
Its alive, people. Still gotta poke around and confirm voltages. Got a feeling I'll be swapping the 5Y3 with a 5AR4: only because I've got a power transformer with a relatively low secondary.
Its pin compatible with the 5Y3, but should result in roughly 40-50 extra volts on the B+ rails. I've got a 250vac secondary feeding the rectifier tube. Typical champ PTs are rated around 330vac. If I find a reasonably low B+ poking around in there I'll make the swap.
Part of why I decided against all the mods is...well...this fucker is compact. Not a lot of space to fuck around. First build: keep it simple.
Gotta carve up some identifying badges for the amp too.
Capacitor reformation & the ability to slowly bring the amp up to normal operating voltages in case there's a catastrophic fault.
As to cap reformation: I've got no idea how long these caps were sitting around before I got em, and for anything up around this voltage it's generally helpful for longevity to bring them up to their operating voltage *slowly* in a controlled manner.
You can just cowboy it, but doing it this way is better for the caps.
It's just for the first startup, I also used a lightbulb limiter while installed the tubes one at a time and confirmed voltages.
Honestly? Yeah. I had MODs in there at first. On paper, they're rated for higher temperatures...but their leads are thinner, and they just don't look as cool.
Yeah. I'm a sucker. I also got the crazy expensive $5.50 a pop Amtrans AMRG carbon film resistors.
The build as is...is just....*dead* quiet on a background noise level. Even running my strat with bare knuckle trilogys. Didn't even have to fuck around with the wire routing.
Granted, I did make a couple of mistakes that I was able to figure out fairly quickly. Accidently grounded the input, forgot a connection or two. Fixed easy.
Sounds cool! Loud for what it is. Super compressed though. Thus me wanting to do the rectifier tube swap.
Next up...a 5E3 build that I'm mostly doing from a kit (gonna do some major mods to that one though). Then...the plan is to do a 20 watt JCM800. Build the head and single 1x12 cab myself. I miss my old 2203 sometimes. Rose colored nostalgia glasses of plugging in a modded DS-1 and goosing the front end of that thing in a shitty hard rock band I was in when I was 18.
Well that’s smart precaution. I just had a thought about powering it variac with tube filaments also running on low voltage and causing excess strain. But yeah, you got it right!
The build as is...is just....*dead* quiet on a background noise level. Even running my strat with bare knuckle trilogys. Didn't even have to fuck around with the wire routing.
Congrats! Nothing like the feeling of the first time you plug in a guitar and play that first time when building an amp.
Like pedals, it's addictive. I'm not sure why my wife complains about the room it takes up, I've only got five 100 watt heads, each with its own matching speaker cabinet. This has led me to building pedals.
Anyway, great looking build! Nice job on the quiet amp and working through the problems.
I’m still in honeymoon phase with my latest tube amp build, which was the first in many years. It certainly took me a hell of a lot longer to get mine done!
Well that’s smart precaution. I just had a thought about powering it variac with tube filaments also running on low voltage and causing excess strain. But yeah, you got it right!
Yeah, that definitely crossed my mind. Granted, though: only the 5Y3 was plugged in at the time. Was a fun little process, honestly. If nerve-wracking.
