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

[Perrow]

Looking real nice there, see you even went for the same labeling solution 

How hot will that mosfet get?

Are you willing to show your layout?

[thomasha]

Hi Perrow,
your build was really awesome, and I looked for similar solutions, as you can see 

When the build is finished and I'm sure everything is working I will post the schematic and layout, but I'm still waiting for some components.

I hope the mosfet will stay cool. As I'm using the max1771, instead of the 555, the mosfet is already way cooler.

I'm testing which would be the best option between irf840, irf740 and irf644. The irf644 is only for 250V, but it has a resistance of 0R28, and is way more cooler than the others, and was the first mosfet used by Nick de Smith. 

Thomas

[Magnus]

Hello,
what about the 440 Ohm-resistor, seems that this value doesn't exist  
Will 470 Ohms be ok for the circuit?


Greetings
Magnus

[frequencycentral]

what about the 440 Ohm-resistor, seems that this value doesn't exist  
Will 470 Ohms be ok for the circuit?

440R does exist. Or you can fudge the value with resistors in series or parallel. Or just use 470R, it'll be fine.

[thomasha]

Hey Magnus,
I used a 1k2 with the 6N16B russian submini.

Finished my amp today, take a look!  I used Max1771 SMPS instead of the 555, and the IRF644 fet. The low ESR capacitor REALLY makes the difference with this SMPS, I tried a normal 10uF and had  a lot of strange noises. After the changing it for a 4.7uF low ESR for pc power supply it was way better.





I still want to add a perforated metal sheet protection, like the lil night train (that's why the color). I used same knobs as Perrow's, they really fit nice in such a small build.

Now his amp has a dark side brother 

After I finish the schematic with the last changes I will upload the layout, if anyone is interested! And a sample, as I always ask for sound samples ...

Thank you Frequency Central for such a nice amp, and Perrow for the awesome idea and tutorial!

Cheers

Thomas

[Perrow]

Congratulations on a really nice build, looks like there's more room to move around in yours than in mine 

Next step will be to move the transformer and tubes inside the enclosure 

[jubal81]

Spectacular build! Mind sharing more about it, layout, schematic?

[thomasha]

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

[Magnus]

Hello,

@Rick:
Thank you  

The wallwart is the same as for the Murder One?

@Thomasha:
Wow, this is really awesome - great work


Greetings
Magnus

[mrsmash23]

THOMASA:
Amazing work! I was thinking about using the max1771 circuit for Superfly too, you were faster
Can I ask you:
- Which brand and series of low ESR caps did you use? Not sure what ESR value is enough for this application.
- R17: 0.1 Ohm / 2W -> Is 2W resistor necessary (I have some 1W of same value)?
- Do you think that transformer you used, Schatz TS 3.60.A, is better match for russian tubes than hammond 125A?
If you think it would be better -> Is there any european dealer for those? Except for their official brazilian web I can't find any additional info.

[thomasha]

Hi mrsmash23,
I would suggest that for the SMPS you take a look at this:
desmith.net/NMdS/Electronics/NixiePSU.html

I used the capacitor that was available, it's for PC power supply, it's a Rubycon, I guess if you can buy from Mouser or digikey, there will be something hundred times better for the same price, like the PANASONIC-ECG.

For the resistor 1W will be fine, I only find the 2W here.

For the transformer, I couldn't find the 125A, and this one I bought is a little bigger (5 mm in every direction), that's why one of the screws is at the left side of the box.
Stay with the 125A or equivalent with 22.5k PP. I know there is the OT5PP and Ampmaker also has one 4W for the 12au7 and ECC99.

And now, the sound sample! Sorry for my bad playing skills...


Cheers, Thomas

[mrsmash23]

Hi everybody!

My submini-mania strikes again. Do you think it would be easy to convert circuit to russian subminis?
Mini Amp 2.0 by FcKw inspired by Trainwreck / Vox Night Train.

Preamp with 3 gain stages + phase inverter = 2x ECC83 -> 2x 6n17b-v
Power amp ECC99 with gain of 22 -> 6n16b-v (gain 25-30) or 6n18b-v (gain 18-28) with Hammond 125A as OT

As high voltage power supply: FC's max1771 circuit which should have enough current to run it.

Do you think this conversion as mentioned would be possible without any significant changes?

Bonus question: Do you think I will still have enough current to add magic eye, EM80? Using regulated 12V@2A supply which should be enough.
 
Schematics:
http://diyguitarfreak.files.wordpress.com/2010/09/miniamp2-schematic1.jpg
Tubes overview:
http://i.imgur.com/OfLQO1j.jpg

[thomasha]

Hi!
nice to see that this thread is still not dead!

Let's see,

my suggestion is: build the amp using the mini amp values and tweak them to sound as you like, I did that with my submini JCM.
To avoid problems with the output stage use the superfly's cathode resistor value, or 1.2k as used by
http://www.dmitrynizh.com/submini-vibro-reverb.htm

The available current with the max1771 is enough, maybe you only need to change the resistor and inductor. My experience says, use 0.05R for more than 25mA and 0.1R for less than that. A bigger inductor will allow more current, a 2A or 3A will be fine, http://www.desmith.net/NMdS/Electronics/NixiePSU.html   explains it all. The IRF644 is better than the IRF840, because it has less internal resistance. Don't forget to put a heat sink on it, it get's a little hot when running 4 tubes.

I see you want to run only 3 tubes, but to use 12V with the heaters you will need 4 tubes, or 3 tubes and a resistor:  400+-40 mA 6V will require at least a 3W resistor with 13.6R, 14R is the nearest value I could find, it will dissipate 2.57 W, so a 3W should be Ok. I had done it with my Russian Murder one, but using the regular 18 ohms 2W resistor and a higher value resistor in parallel, but I only had a low wattage one, so the first time it went to hot and almost unsoldered itself.

Assuming that the magic eye consumes 300mA you can use a lower wattage resistor in parallel to dissipate 60 to 140mA. Considering the highest current the resistor would dissipate: P=VI=6*0.14=0.88W and would have a resistance of: R=V/I=6/0.14=42.85R. So, instead of using the bigger wattage resistor alone you could use your magic eye and a smaller resistor to dissipate the same current as one 6N16B or 6N17B for example.
The heater's max. current is: 2x440mA =880mA (2 tubes in series in parallel with the remaining tube, magic eye and resistor). I also use a 12v 2A supply with 4 submini and 1 SMPS and it works.

Another approach would be use the magic eye alone with a resistor, and the bigger wattage resistor in series with the signal tube, but it would require an extra 300mA current.
Now the heater's current would be 880+300=1180mA. Don't forget that you also need current for the SMPS, in this configuration ideally you still have aprox. 9.8VA available. Considering the max1771 efficiency it's enough to obtain the 235V you need with a decent current.

If you need, I can help you, just ask if you have any question. take a look at my Amp here:
http://www.diystompboxes.com/smfforum/index.php?topic=79544.msg942552#msg942552

Cheers
Thomas









   

[tranceracer]

Finally got the materials to build this!  (:
Couple of questions came up.  How hot are the 6111WA tube supposed to get.  Mine seem to get pretty hot.  They are hot enough to touch but can't keep my finger on the tubes for more than 4-5 seconds.
The other question I have is the pre-amp section is working because I can connect it up direct to my amp and get sound but the power amp section gets nothing.

I'm thinking it may be the transformer but I'm using this one:
https://www.tubesandmore.com/products/P-TF22921

I've wired up the power amp section two ways, using the Sub Zero which uses the 6111 tubes and the Firefly which uses the 6111WA.

Any assistance will be greatly appreciated.

-Byron

[frequencycentral]

That transformer is single ended. It won't work with the Superfly's self split push/pull arrangement as there is no centre tap. You could modify the output section to work, but best get a Hammond 125a. Just building a Superfly myself today.

[tranceracer]

Thx FC for the response and assistance!
Yes, I suspected that the xformer may be the problem.  BTW, Is it normal for the tube to get pretty hot?

Just the preamp section sounds pretty nice straight into a solid state amp.  (;

-Byron

[frequencycentral]

Yes they should be almost too hot to touch. :-)
Good luck with your build.

[tranceracer]

Yes they should be almost too hot to touch. :-)
Good luck with your build.

Hey Thx FC!
Where are you ordering the transformers from?  I just ordered one from Mouser w/ shipping cost me around $40 bucks.

[frequencycentral]

UK:   http://www.bluebellaudio.com/

EU:  http://www.musikding.de/navi.php?suchausdruck=hammond+125a&JTLSHOP=7ab467bfc69c4cf0a850f1aba0e3f97c

[nickds1]

If needs be, I'm happy to answer questions about the MAX1771 design - I'm the author of the one referenced in this thread - many 100s have now been built, lots for audio use...