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

[Perrow]

Edit: Stupid person using mobile app.

[Mustachio]

Nice Perrow! I didn't even think about bending the pins upwards on the IC I think ill do that. but the tubes will have to be mounted on the back which isnt a biggie I can do it. It might work out well for the way the board is mounted. Ill put foam on the bottom of the pcb and mount it to the inside top of the box and maybe it will help dampen vibration.

And for the OT's output , Thats what I was thinking but I haven't read much about the OT yet. So either of the 2 middle lugs to either of the tip/ring .

Thanks!

[Perrow]

Yeah, tubes on the other side is a nice idea for this circuit. I've thought about building me another one and I might do just that. Though I think I'll draw a layout specially for that

[Mustachio]

I wired this up a few days ago and it worked right from the start! Was really happy to have it working. I need to widen a hole or 2 on my box to make things fit a lil better. I think I'm off about 1mm on my output jack and everything will fit perfect. So at the moment I have the board sitting outside the box. And its quiet no hum or noise from the power. I had it running at 185v no problem and took it up to 220v and still no problem just a little more volume and head room. I used a 7327 and a 6111WA .

It was a little dark/muddy with the 0.1 uf at C2 and C7 . So I took them out and put in sockets so I could test different values. When I did that something went wrong and I wasn't sure what. It stopped having any output but still good voltage to the plates so I knew power was fine but the audio path was bad. Double checked all my soldering and It was fine. Figured I would change tubes since I had 10 more on hand and bam instant working again! This time I used a 6112 in the pre. Sounded great with 0.022 uf at C2 and C7! Brought out all the articulation of my playing , The pickups in my main guitar are not very high output or tone so this value worked great for me. If anyone had a brighter sounding guitar I'd suggest the 0.033 uf in those spots.

One other thing I realized last night I used a 100K lin pot for gain instead of the 1m log. Gonna change that out maybe tonight or soon. I'm guessing this will give me more gain/output , It was just a mistake I grabbed the wrong pot. My only worry is that with the change I might end up hearing some noise at higher levels. Only one way to find out

So far its a really cool sounding amp. I went with no tone stack because I usually find simple is best, and I figured Id just change the caps to fit my needs. I had a few 2x12 amps on the side that had the speakers wired so I tested it with them. With a fuzzface or tube screamer It really pushes it , can get some nice feedback. Even without the pedals it can feedback a little and even rattle a few hanging light fixtures haha!

Once I get it all fit in the box better and change the pot ill try to make a little demo video of it.

[Mustachio]

Ok so I got it going pretty good and I'm pretty much happy with it but ..... It is really missing the high end.

I have socketed C2 and C7. Originally .022uf in the firefly, I believe changed to 0.1uf in Ricks layout. I tried tons of caps - 0.1, 0.022, 0.0022 , 0.001

So yeah I went down to 1,000 pf and really not much of a difference at all    It did make it just a hair brighter.... I think.... But not anywhere near bright enough. I'm not expecting vox like high end shimmers but this just isn't cutting through for me. It sounds good on the bridge pickup But way to muddy in the neck or middle. I would prefer the tone I get from the bridge when I'm in the neck position and so forth down the line.

Any tips on brightening this up, Its really close just no cigar yet. Ill post a video of it soon.

[makaze808]

Hi has the schematic gone AWOL or should I go to spec savers

Please put me out of my misery and link me to the schematic, thanks.

[Mustachio]

Pelle has all the info put in one place here.

http://rumbust.net/Superfly

The first page has the original schem and page 7 has a schem with a tone stack

And page 9 has a pcb layout with changes

[Mustachio]

I found some info about cap selection switches for the firefly and noticed it all looks like what zvex does as well.

C2 and C7 are the ones to change in this layout

I believe at the moment I have 330pf in C7

And

0.022uf in C2

I have em socketed , but you could easily put them on a switch and alternate between 330pf and 220pf for C7

and 0.1uf and 0.022uf in C2.

And that seems like what the zvex has set up for its switches.

But the 330pf and 0.022uf work out best for me. It's not overly bassy any more has more high end bite and when you clean it up it makes things sound more clear.

I have mine running at 231v at the moment with these cap set ups and it will go from pretty clean to pure blues tube drive maxed out.

Dremeled out the top to give the tubes more room and make the mounting work better. Gotta file down a few spots, add the led, sand it and paint it next!

[angrykoko]

Can someone help me with a question about the wall wart.

I fried the inductor on my first try of this amp, I was using a 12v 1amp PSU and accidentally had the trim pot so it was trying to push max volts (and a tone pot wiring issue too).

Anyway,  fixed the broken bits, sorted out the the trim pot and the tone control and fired it up again this morning with a 12v 400ma PSU and it works like a charm except for the issues of not having enough current.

Is there any reason I *cannot* use the 12v 1A PSU on this? 

It's too much of a pain to pull apart if I fry any parts and it's the only other psu I have on hand.

Thanks in advance!
Koko

PS>  at 160v and poor current it sounded very cool through a Vintage 12 and a C de-tuned guitar... !

[Mustachio]

Hmm that's strange.

I'm using a 12v 1amp switching wall wart (PSU) and it works just fine. I've also taken it all the way to the top of the trim with no problems. Here's the model I'm using

http://www.digikey.com/product-detail/en/WSU120-1000-R/237-1456-ND/3094982

It's a switching PSU so there is a chance of heterodyne but I haven't had an issues.

I'm wondering if its your inductor's rating. Maybe post up some info on the power supply your using and the inductor so we can take a look at the data sheets.

I think each tube is going to want around 300ma

I know a few people had issues with popping inductors I'll take a look later for the inductor I used.

[angrykoko]

Thanks!

It very well could have been my bonehead wiring of the tone pot that caused the issue the first time.. just being gun shy 2nd time around since I remember the recommended PSU being 500ma somewhere in this thread.

The inductor is the same one that FrequencyCentral used, it's rated for 670ma
http://www.mouser.com/Search/ProductDetail.aspx?R=22R104Cvirtualkey58010000virtualkey580-22R104C

I'm also using FrequencyCentrals layout with an etched board.

The 1A psu is from a yamaha keyboard we have around the house.

Thanks again.

[Mustachio]

Is the yamaha keyboard psu your using out putting AC or DC ? center negative ?

The inductor should be ok ... maybe ... I think it depends on how much current the circuit will pull. And how much will be getting pulled through that inductor.

Now I'm not totally sure but I think just because the psu is rated at 1amp it will only feed the circuit what its trying to draw, up to 1amp and not just constantly push 1amp into the circuit.

I think the inductor I used was good up to 1.5 or 2amps.

[angrykoko]

DC, Center positive (but my hookup wiring takes that into account and the dc jack is the plastic type we normally use for pedals )

Now I'm not totally sure but I think just because the psu is rated at 1amp it will only feed the circuit what its trying to draw, up to 1amp and not just constantly push 1amp into the circuit.

This what I always thought too, didn't know if there was something special with this nixie circuit thought, sounds like not.

Ok, I'm feeling better that this may be ok since your using a 1a psu.  I'll give it a try when I get home and report back with either a big smile or very sad face

[angrykoko]

It LIVES!!!
Thanks Mustachio!

[Mustachio]

Woot! Looks great! Congrats!

Another thing to keep in mind is , don't power it up without a speaker plugged in. Without load it can mess up the transformer. One trick is to use like a 2watt 8 ohm resistor with a stereo switched jack so when the cable is unplugged it has 8ohm resistance. I haven't done this myself yet but its a good idea just in case.

[thomasha]

Nice Build! soundclips?

Has anybody tried a different approach for the output stage?

I saw this at http://www.dmitrynizh.com/submini-vibro-reverb.htm:



Instead of grounding the second triode's grid, the grid is connected through a voltage divider to the first triode's plate.

I made a quick simulation using LTSpice and the result was an increase in volume.

With the extra resistors would it be possible to obtain more gain or headroom?

Thomas

[angrykoko]

Another thing to keep in mind is , don't power it up without a speaker plugged in. Without load it can mess up the transformer. One trick is to use like a 2watt 8 ohm resistor with a stereo switched jack so when the cable is unplugged it has 8ohm resistance. I haven't done this myself yet but its a good idea just in case.

Yeah, I'll get that resistor on there when I add the LED.

What about a bypass switch?  I added a pad to do but didnt hook it up but, I never see them on these sub-mini's (not even Zvex's looks like it has it).  These little tubes are tough eh?

The max output is about the same or just slightly more as what I remember the ROG Ruby being, is that about right?

[Mustachio]

Hey Thomasha, back in oct of '12 Rick gave me that link and I read over it a bunch But never got around to trying it out.

http://www.diystompboxes.com/smfforum/index.php?topic=99454.0

Really good looking build and info there , It's still on my todo list.

I did record some sound clips of the superfly last year but never uploaded them. Maybe ill try to do a proper sound demo soon.

I'd love to see/hear some one do a submini amp with reverb and trem/vibe would be the bee'z knee'z .

[thomasha]

Mustachio,
I built a Jcm inspired amp using the russian subminis and the Long-Tailed Pair phase inverter in the third schematic.

Unfortunately there is only simulation data available, would be interesting to see some build reports or something.

I tried Rick's Vibratone, but the murder one output stage was not enough for me, and the tremolo was not what I expected.

This superfly will be my next build, but I'm thinking of using the Max1771 SMPS since I already build 3 of them.

Is the 555 SMPS quiet? Or is there some switching noise at max. gain? And what about the brightness of the amp?

My murder one had a flabby bass, and only after reducing the first coupling capacitor to 2.2nF it was a little better.

Thomas

[MetalUpYerEye]

Its been awhile since i've posted here... I had previously built the full layout posted earlier in this site without success and having the Nixie PS and tube circuits on the same board proved to be too confusing for me to handle so I decided to try building the power supply by itself and then if that worked, continue to the tube stuff. After getting the power supply working I sort of lost interest.

I found my Superfly stuff in the garage last weekend and decided to give it another go. This time with better results. The power supply gives me between 100 and 190 volts DC. The amp plays and sounds good but oscillates badly if I turn up gain and volume past 3/10 or so.. I've tried searching this thread (and the Murder One) thread for posts concerning oscillation but have had limited results. Any ideas what might be making a circuit like this oscillate so badly?

A little bit of info.. My tubes are a 6112 and a 6021. I've build the Nixie and tube sections on separate boards. I've tried running it at everywhere between 100 and 190 volts with no change to the oscillation problem, just less headroom and volume. My AC adapter is a 12v regulated, 3A since thats all I had laying around. It gives me a solid 12.6v. I've tried swapping out the 555 ic and bc547 with no changes. I noticed that I accidently put the bc547 in backwards and there was no change either..

Any help would be awesome. Thanks in advance