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

[Perrow]

thanks guys and thanks for the link. I often forget about our galleries here.
I guess I'll start with the SMPS and see if I can make it work. And then continue with the amp.

The leg is killing me. It doesn't hurt much but I have to stay at my parents' (I live on fourth floor with no elevator) until they allow me to step on the leg. I basically just took my guitar and notebook but left the amp and DIY stuff at my place. So it's all planing future builds for me now.

I actually googled something like "nixie smps vero" and that was the first or so result.

I can think of many worse fates than spending a week or two with a guitar and DIYLC

I'm currently verifying my new layout for this project, got the smps working today and fixed at least three problems around the tubes. The smps was probably working already, but one of the OTs connections had a solder bridge to ground that I found and fixed.

While going over the board with a magnifying glass I then spotted two component legs that were not soldered in

I still got no sound and only after leaving "the shed" realized I have the gain and volume pots connected incorrectly, so hoping that is the last error (yeah right) I might have it rocking tomorrow.

Finally, a debugging tip; to verify that the 555 is ticking along as it should (at least verify to some degree), add a 10uF or 22uF cap in parallel with C4 and solder in a led in series with a resistor between leg 3, of the 555, and ground (pin 1) and remove the MOSFET (IRF740). You should be able to see the led blinking. If C4 isn't broken the 555 should now be verified.

[Perrow]

Why do you guys insist on building these in such large enclosures? 



I'll include a gutshot in this thread.



More info coming, just got to present it in a way that'll make sense to someone else than me

[jaapie]

Hey, I had a sweet 60 year old radio lying around dying for a new life. Plus, now I've got room for a little speaker and a 12v battery

[Govmnt_Lacky]

@Perrow,

I think that is a pretty sweet build. Being able to squeeze that into a 1590A is phenomenal work!! 

Perhaps you can help me understand what is the need for such "compactness" of the amp 

Do you plan on using it strictly as some form of headphone amplifier? A tiny cabinet to drive?

Was it merely a challenge that needed conquering? I can't wrap my head around the need for such smallness... please enlighten me 

[Perrow]

@Perrow,
...

I can't wrap my head around the need for such smallness... please enlighten me 

The short answer is: The devil told me to 

The slightly longer answer is that I thought about building this and was looking at Ricks layout and thought; "I think I'll draw a schematic for just the SMPS, maybe I'll learn something, and maybe it'll be nice to have separate if and when I decide to build this".

Said and done I did a layout for just the SMPS and, hey, this could be quite compact. Redid the layout a couple of times and suddenly thought, I wonder if I could stack two boards and make this fit into a 1590A (was looking at the 1590A thread ever so often and admiring their work).

Fast forward some six or seven months and I don't know how many hours of redrawing this baby in DIYLC, learning how to etch sourcing parts and I can finally post my own 1590A build 

[zambo]

Its nice but I think I would like mine in a altoids can. The small one  Man thats some sweet work on that. Truly awe inspiring!

[Scruffie]

Right... well, my layout works to a point I know that much now.

I wont call it quite verified, I get guitar through but oscillation builds up as the tubes warm up however i'm hoping this is just due to my supply being only rated for 300mA (I did find a 500mA supply but it's Centre Positive... and put out 13.5V instead of the 12.6V it said  ) rather than a layout issue, that and it's just a big mess of wires at the moment.

Anyway, now I know I can get it to work, i'll start on a new layout with the tubes and pots mounted the right way this time and space some things a bit better.

[iccaros]

Why do you guys insist on building these in such large enclosures? 

I like my large enclosure.. I am putting a 3" speaker in mine

[zambo]

the lunch box is sweet!

[Scruffie]

Right... well, my layout works to a point I know that much now.

I wont call it quite verified, I get guitar through but oscillation builds up as the tubes warm up however i'm hoping this is just due to my supply being only rated for 300mA (I did find a 500mA supply but it's Centre Positive... and put out 13.5V instead of the 12.6V it said  ) rather than a layout issue, that and it's just a big mess of wires at the moment.

Anyway, now I know I can get it to work, i'll start on a new layout with the tubes and pots mounted the right way this time and space some things a bit better.

Okay... now i'm getting somewhere!

Once I turned the voltage up past 200V the Oscillation stopped and I now have a working full tube Superfly! (well apart from the odd backwards pot but... ah well)

Now... some things i've noticed that I wanna check on, my 12AU7 is noticeably hotter to the touch than the AX7, is that normal? It's not burning my fingers but I can feel a difference in heat.

The IRF840 in the SMPS is getting a bit hot to the touch too after a few minutes of playing, is this down to my weak mA supply or something I should be concerned about... I recall Rick said his MAX1771 ran pretty cool. Admittedly my Voltage does seem to fluctuate a little bit but it doesn't seem to have done any harm so far.

I'm gunna make the new layout for a switchable Baxandall Tone Control I think if I can & add a Standby Switch, i've already shrunk down the Charge Pump considerably while allowing more space for the components that need it and cut the board space to make it easier to fit a 1590BB. I may also make it so the tube heaters are wired seperatley (like on the actual Firefly) to save room and for a hopefully a tidy build with less chance of issue.

[iccaros]

Right... well, my layout works to a point I know that much now.

I wont call it quite verified, I get guitar through but oscillation builds up as the tubes warm up however i'm hoping this is just due to my supply being only rated for 300mA (I did find a 500mA supply but it's Centre Positive... and put out 13.5V instead of the 12.6V it said  ) rather than a layout issue, that and it's just a big mess of wires at the moment.

Anyway, now I know I can get it to work, i'll start on a new layout with the tubes and pots mounted the right way this time and space some things a bit better.

Okay... now i'm getting somewhere!

Once I turned the voltage up past 200V the Oscillation stopped and I now have a working full tube Superfly! (well apart from the odd backwards pot but... ah well)

Now... some things i've noticed that I wanna check on, my 12AU7 is noticeably hotter to the touch than the AX7, is that normal? It's not burning my fingers but I can feel a difference in heat.

The IRF840 in the SMPS is getting a bit hot to the touch too after a few minutes of playing, is this down to my weak mA supply or something I should be concerned about... I recall Rick said his MAX1771 ran pretty cool. Admittedly my Voltage does seem to fluctuate a little bit but it doesn't seem to have done any harm so far.

I'm gunna make the new layout for a switchable Baxandall Tone Control I think if I can & add a Standby Switch, i've already shrunk down the Charge Pump considerably while allowing more space for the components that need it and cut the board space to make it easier to fit a 1590BB. I may also make it so the tube heaters are wired seperatley (like on the actual Firefly) to save room and for a hopefully a tidy build with less chance of issue.

Some Thoughts to what your are seeing...

From reading, This is how I understand it and could be wrong..
the inductor will ramp up to its max current in a given time frame, which based off the turn on resistance of the IFR840 is very low, which makes it fast, compared to the 740. you set voltage by adjusting the duty cycle of the PWM you are getting from the oscillator. If the duty cycle is longer than it takes to max the inductor the IFR is stuck with the extra current, which becomes heat.
In the original SuperFly this was handled with a heat-sink.  Others have noted that raising the value of the inductor can help with this, say a 200mH or so, extending the time before the inductor pushes back.
As for Oscillation, I would look at the cap values, as they will smooth out the ripple based on the duty cycle of the IFR, and
As for one tube getting hotter than the other, I have an IR thermometer I use to monitor them, I find that one tube is always hotter than the others, but as long as they do not go near bulb max as listed in the datasheet I do not worry.

All of the reading I have done, also point out that you may want a 1A Power supply, but if its working and the supply is not getting hot, then don't worry.

But using the IRF840 and a larger inductor (amprage along with ratings) should get more current through to the tubes..

[Scruffie]

Right... well, my layout works to a point I know that much now.

I wont call it quite verified, I get guitar through but oscillation builds up as the tubes warm up however i'm hoping this is just due to my supply being only rated for 300mA (I did find a 500mA supply but it's Centre Positive... and put out 13.5V instead of the 12.6V it said  ) rather than a layout issue, that and it's just a big mess of wires at the moment.

Anyway, now I know I can get it to work, i'll start on a new layout with the tubes and pots mounted the right way this time and space some things a bit better.

Okay... now i'm getting somewhere!

Once I turned the voltage up past 200V the Oscillation stopped and I now have a working full tube Superfly! (well apart from the odd backwards pot but... ah well)

Now... some things i've noticed that I wanna check on, my 12AU7 is noticeably hotter to the touch than the AX7, is that normal? It's not burning my fingers but I can feel a difference in heat.

The IRF840 in the SMPS is getting a bit hot to the touch too after a few minutes of playing, is this down to my weak mA supply or something I should be concerned about... I recall Rick said his MAX1771 ran pretty cool. Admittedly my Voltage does seem to fluctuate a little bit but it doesn't seem to have done any harm so far.

I'm gunna make the new layout for a switchable Baxandall Tone Control I think if I can & add a Standby Switch, i've already shrunk down the Charge Pump considerably while allowing more space for the components that need it and cut the board space to make it easier to fit a 1590BB. I may also make it so the tube heaters are wired seperatley (like on the actual Firefly) to save room and for a hopefully a tidy build with less chance of issue.

Some Thoughts to what your are seeing...

From reading, This is how I understand it and could be wrong..
the inductor will ramp up to its max current in a given time frame, which based off the turn on resistance of the IFR840 is very low, which makes it fast, compared to the 740. you set voltage by adjusting the duty cycle of the PWM you are getting from the oscillator. If the duty cycle is longer than it takes to max the inductor the IFR is stuck with the extra current, which becomes heat.
In the original SuperFly this was handled with a heat-sink.  Others have noted that raising the value of the inductor can help with this, say a 200mH or so, extending the time before the inductor pushes back.
As for Oscillation, I would look at the cap values, as they will smooth out the ripple based on the duty cycle of the IFR, and
As for one tube getting hotter than the other, I have an IR thermometer I use to monitor them, I find that one tube is always hotter than the others, but as long as they do not go near bulb max as listed in the datasheet I do not worry.

All of the reading I have done, also point out that you may want a 1A Power supply, but if its working and the supply is not getting hot, then don't worry.

But using the IRF840 and a larger inductor (amprage along with ratings) should get more current through to the tubes..

Okay then, i'll stick in a larger inductor, i'm using a small one as it fit the layout better but this thing is such a mess now anyway, who cares, i'll add a heat sync at some point anyway to the IRF, can't hurt.

Yeah the 12AU7 is hot like I can feel the heat coming off it but it's not getting burning hot, just wanted to max sure one tube wasn't over working or under working or something.

My Supply is lacking i'll admit, but it does seem to function okay for the moment at least, i'll upgrade it when I get something boxed up.

The oscillation is no longer an issue, it just didn't like the lower voltages, perfectly clean now.

I think it's time to move on to the next layout evolution of this one now! Seems to work well enough.

[Perrow]

I am putting a 3" speaker in mine

I'm not

[Jaicen_solo]

Ok, quick question.
I haven't built one yet, though I have a PCB layout for the Firefly i've not got all the parts.

Using a 12au7 as a PP power amp, how close does it sound to a pair of EL34's?
I know there are many variables involved, but it's something i'm interested in for my mini Plexi.

[iccaros]

Using a 12au7 as a PP power amp, how close does it sound to a pair of EL34's?

nothing at all, but the same,  the 12au7 will overdrive quicker but 99% of the people in the world will not know the diffrence
 

[Jaicen_solo]

Errmm, ok. So the same, but not?

[zambo]

i dont think they sound very similar. Listen to some firefly clips and you will hear them. lil night train does to I think.

[iccaros]

Errmm, ok. So the same, but not?

Since sound is perceived by the person hearing, people who know what a standard EL34 power-amp sounds like, will not ever think a 12au7 sounds the same.. But 99% of the people in the world do not care, it either sounds good or bad.  Now I made the point of saying standard, because the sound is as much based on the design as it is the tube type. you can put  an EL34 in triode mode and it will sound more like a 12au7.. It is claimed that the 12au7 sounds more like  a power tube, but what does that mean? what is the bases for measuring that, except with our ear, where if someone said, this sound like that.. most people may agree, with out even knowing what X sounds like, or even side to side as they are expecting it.

Zambo has some examples, but I could not tell you by ear what tube he is using..

[Jaicen_solo]

Hmm, I guess i'm looking for the general character and response, rather than a particular sound.
I'm currently running a SE EL84 amp, which has a great tone and response but it doesn't have that sound you get when you dig into something like a JTM45.
The PP thing i'm looking for is that 'chunk' sound when you dig in or palm mute. A SE seems a bit sweet, I just can't seem to get it to do that particular sound.

[lopsided]

My leg still in plaster, but already able to walk somehow, so I moved home.
And couple of minutes ago I had 260V on my breadboard. Impressive.  Just for a second - I didn't want to push it, but it seems that I am ready for putting the SMPS on vero.
Had a little stupid accident mistaking the big 330uF cap for the big 2,2uF/450v cap. Wondered why it didn't work, but found out the mistake before anything bad could happen.
Can't wait to try the amp then.

l_s