Author Topic: "Superfly" - submini tube version of Doug H's Firefly  (Read 264219 times)

Marcos - Munky

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #580 on: May 09, 2018, 12:26:20 PM »
Question on that 440r cathode resistor. How important is to use this value? I mean, what's the difference if I use a 390r or 470r instead?

rankot

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #581 on: May 09, 2018, 01:42:34 PM »
Perhaps not too important, but you can use two 220R in series. ;)
Ampegulator, Bassballs, Bazz Fuss, Bearhug Compressor, Bronx Cheer, Clean Sweep, Demeter Compulator, Electra Distortion, Engineer's Thumb, Hybrid Fuzz, Orange Squeezer, ProCo Rat, Ross Compressor, Valvecaster, 6J6, SFT 2, Ugly Face, more to come...

Marcos - Munky

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #582 on: June 22, 2018, 11:20:53 PM »
Ok, so I'm almost ready to test my Superfly. Just need to solder the pots. I just have two more questions (that may be answered in this topic, but I'm still didn't finished to read all the posts):

1- What's the output power of the Superfly? The version without a tone pot.
2- I'll use the enclosure as the heatsink for the IRF740. Do I need to isolate the IRF metal tab from the enclosure?

bluebunny

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #583 on: June 23, 2018, 06:02:49 AM »
1- What's the output power of the Superfly? The version without a tone pot.
2- I'll use the enclosure as the heatsink for the IRF740. Do I need to isolate the IRF metal tab from the enclosure?

I don't recall any power output being mentioned, other than it being "wife-worryingly loud".   :icon_wink:

My datasheet doesn't show how the tab is connected, but it would be easy enough to find out with a DMM.  If it's the source, then I guess it would be fine (the schematic shows it's connected to ground).  I'd be inclined just to insulate the tab regardless.
Ohm's Law - much like Coles Law, but with less cabbage...

Marcos - Munky

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #584 on: June 23, 2018, 11:30:01 AM »
The datasheet I used doesn'tshow the tab connection too, I just checked and it's connected to the drain. So, it needs to be insulated. Bad news, since the next store that sells electronic stuff is about 25km away from home, but I should be near the store this week.

As for the power, it's really not mentioned and I didn't found this info on google. I asked because the original Firefly transformer is a 3.5W one (oversized). To keed the size down, I ordered a 1W transformer. Since the max plate dissipation is 1W, the output should be lower than 1W.

xaxxop

Re: "Superfly" - submini tube version of Doug H's Firefly
« Reply #585 on: July 03, 2018, 02:09:20 PM »
Thank you guys! I'm really happy with the sound of this amp!

I made a PDF file with layout, and schematic, the link is:

https://dl.dropboxusercontent.com/u/10420127/Superfly%20Project.pdf

The PCB board is already scaled (that's why it's a pdf file...)

Tomorrow I will make a sound sample, if possible.

Greetings,

Thomas

Thank you guys for sharing all these beautiful mini amps, I would like to have a look at the pdf file but the link is broken, could someone please post it again or send to by pm. I would appreciate it. Thanks