Harry Klippton
Well-known member
So how's about sticking this in a nice enclosure with a space heater and the eventual ir loader? Any reason I couldn't do that?
Firebox - tube power amp emulator
- Thread starter vigilante398
- Start date
vigilante398
Authorized Vendor
Nope, that's literally the plan. Throw a tube preamp in the front end in the same box and call it a complete gig-friendly tube amp replacement.
Harry Klippton
Well-known member
Whoops is the space heater not the preamp?
vigilante398
Authorized Vendor
The Space Heater is a preamp, but if I'm making a big fancy all-in-one box then I would personally want a bit more complex of a preamp.
Harry Klippton
Well-known member
This is turning out to be more of a sushi boat 
vigilante398
Authorized Vendor
Yeah I did an amp build years ago that I called Bento Box, seems like more of a fitting name for something like this.This is turning out to be more of a sushi boat
Harry Klippton
Well-known member
I'm here for it though. I barely get to play the amp I built earlier this year
Now I'm really wanting the picnic box this is turning in to, I just found a supplier of a smaller board for a 10watt that says "The input signal can come from a guitar preamp or your favorite mp3 player. what are your suggestions for a DI o vigilant 1? I haven't even considered gigging for 20+ years and I spent more time as the roadie/tech for the guys who COULD play other's songs. Since all I can fling out is 30-90 second loop, I rather record for a friend's animation works.
vigilante398
Authorized Vendor
MY favorite DI is obviously a tube DI and obviously it's one I made myself
I use Lightning Boy Audio transformers (made in New York) and I love the sound of them. In an A/B test against a Jensen (I built a preamp with both and a toggle switch to go between the two) I found I prefer the Lightning Boy; it just has a little extra "something". You can buy the transformers individually from him, or you can buy them as a finished DI box which he calls T.I. for "thicker injection". Super nice dude, super cool to work with, I'm not affiliated in any way other than I buy transformers from him just about every month. https://www.lightningboyaudio.com/store/p68/thicker_injection_box.htmlvigilante398
Authorized Vendor
Seriously, can't recommend him enough. I would say tell him I sent you, but it wouldn't get you a discount or anything, he would probably just say "oh, okay cool."
Chuck D. Bones
Circuit Wizard
when do we get to see a schematic?Extremely minor update: PCB fabrication is complete, boards are pending shipping right now!
My IR loader prototype PCBs have shipped, I'll probably start a new thread for those when they get here, ETA is friday.
vigilante398
Authorized Vendor
It's nothing mindblowing, basically a simple tube preamp into an AX84 Firefly power section with a dummy load on the output transformer secondary. I have the dummy load on a switch so I can switch it off and run a speaker just for fun, but the main intention is to use it with the dummy load.
The parallel 47n coupling caps on the tube are because JLC ran out of my 100nF high voltage caps, so this is the closest I can get without soldering things myself
I have these boards in now, but I've been swamped and haven't had a chance to put one together yet.
Chuck D. Bones
Circuit Wizard
Thanks!
You could take out 1/2 of those 47nF caps and it would sound the same.
How high the voltage? It's like "How High the Moon" only without all of the overdubs.
You could take out 1/2 of those 47nF caps and it would sound the same.
How high the voltage? It's like "How High the Moon" only without all of the overdubs.
Passinwind
Well-known member
It's nothing mindblowing, basically a simple tube preamp into an AX84 Firefly power section with a dummy load on the output transformer secondary. I have the dummy load on a switch so I can switch it off and run a speaker just for fun, but the main intention is to use it with the dummy load.
The parallel 47n coupling caps on the tube are because JLC ran out of my 100nF high voltage caps, so this is the closest I can get without soldering things myself
I have these boards in now, but I've been swamped and haven't had a chance to put one together yet.
View attachment 30170
What output transformer are you using? I worked on a similar design for an amp maker several years ago and we went with Cinemag, which were surprisingly inexpensive for a custom wind. I think I still have a couple of those boards kicking around actually...hmmm.
vigilante398
Authorized Vendor
B+ is 240V on this one, I don't usually go higher than that on SMD builds.
I'm not sure, I'm still a ways off on the final design. Just the power amp sim by itself is in a 1590X though, so the final thing with everything together is going to be BIG.
I'm using a Hammond 125A, I had a handful of them kicking around from an old project that never ended up getting past prototype.
Passinwind
Well-known member
Cool, looks pretty similar to the custom Mercury Magnetics one I mentioned in one of these threads.
Chuck D. Bones
Circuit Wizard
I've gotta try that out!
If you don't need a lotta bandwidth, then Hammond 125A is fine and not too expensive.
There are design rules (conductor spacing) for high voltage that are applicable above 300V.
If you don't need a lotta bandwidth, then Hammond 125A is fine and not too expensive.
There are design rules (conductor spacing) for high voltage that are applicable above 300V.
