"Superfly" - submini tube version of Doug H's Firefly

[Marcos - Munky]

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]

Perhaps not too important, but you can use two 220R in series.

[Marcos - Munky]

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]

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".   

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.

[Marcos - Munky]

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]

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 

[jma38]

I've built the original Superfly, everything looks good and all connections are properly soldered but for some reason when I turn on the power the tubes won't even light up. Has anyone else had this issue?

[bluebunny]

Are your tubes known to be good?  Do you have 6V across each heater?  (Pins 3-6.)

[jma38]

The tubes are good, I even swapped them out for extras I got(just in case) I also used my multimeter to see if the power is actually getting to the amp and nothing.

[frequencycentral]

...everything looks good and all connections are properly soldered...

Clearly not!

[bluebunny]

You need to trace where your 12V enters your board and find out where it stops.  Can you post photos?  More eyes might help.

[jma38]

...everything looks good and all connections are properly soldered...

Clearly not!

True now that you mention it

[jma38]

You need to trace where your 12V enters your board and find out where it stops.  Can you post photos?  More eyes might help.

Here's a picture of the soldered board. I'm realizing I'm definitely not as adept at soldering as Rick(the soldering on the back of those first Superfly prototypes was downright beautiful).

[frequencycentral]

...everything looks good and all connections are properly soldered...

Clearly not!

True now that you mention it

Sorry if that seemed harsh! I spend a lot of time helping people debug. The absolute worst starting position is "I've done everything right and it doesn't work". First step of debugging is to own not having done everything right. Second step is to find out what dumb thing you did. 😀

[jma38]

...everything looks good and all connections are properly soldered...

Clearly not!

True now that you mention it

Sorry if that seemed harsh! I spend a lot of time helping people debug. The absolute worst starting position is "I've done everything right and it doesn't work". First step of debugging is to own not having done everything right. Second step is to find out what dumb thing you did. 😀

Oh no problem, I didn't interpret that as harsh and yes it's true, the first step to finding the problem is admitting that something wasn't done properly. I enjoy this DIY stuff so much I'm not even frustrated going in to debugging the board.

[jma38]

Just to eliminate a possible power supply issue I've ordered a new 12v 500ma power supply. It should be here in about a week.

[bluebunny]

Have you measured the power supply as requested earlier?

[jma38]

Have you measured the power supply as requested earlier?

Yes, my meter was reading absolutely nothing.

[antonis]

Yes, my meter was reading absolutely nothing.

Your meter might need power supply, also..

More seriously, what do you mean with "nothing"..??

[jma38]

Yes, my meter was reading absolutely nothing.

Your meter might need power supply, also..

More seriously, what do you mean with "nothing"..??

  It isn't reading a voltage at the power input of the amp. Nowhere on any other part of the circuit either.