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

[frequencycentral]

I would think it would be a perfect marriage of the two. You shouldn't have top change anything, just a case of getting the SMPS running right. In fact I'm planning to build a Suprfly using the MAX1771 at some point myself. You can get 0R100 1 watt resistors from Banzai, you could use two in parallel for 0R050, or try 0R100 as the Rsense resistor, I've had good results with that. http://www.banzaimusic.com/Royal-Ohm-0-1-ohm-1W.html

[frequencycentral]

One question, Have you tried 2 similar circuits with both nixie powersupply, and your voltage multipliers (the ones with diodes, caps and a max1044)?
I wanna check hoe the different voltages affect really the sound...

With the nixie supply you can dial the voltage right down to around 100v if you want to check how a reduced volateg affects the sound.

[Scruffie]

I would think it would be a perfect marriage of the two. You shouldn't have top change anything, just a case of getting the SMPS running right. In fact I'm planning to build a Suprfly using the MAX1771 at some point myself. You can get 0R100 1 watt resistors from Banzai, you could use two in parallel for 0R050, or try 0R100 as the Rsense resistor, I've had good results with that. http://www.banzaimusic.com/Royal-Ohm-0-1-ohm-1W.html

Aha, Perfect! Cheers Rick!

[makaze808]

Hello.  The Hammond 125a, is it the 125a or 125ase I need.

Thanks.

I also have several spare 6111wa tubes for UK delivery for £9.00

[makaze808]

What spec 12v power supply do I need?

[makaze808]

Doh, output is from transformer.

[frequencycentral]

Hello.  The Hammond 125a, is it the 125a or 125ase I need.

The OT is a 125A push/push, not the 125ASE which is single ended.

I also have several spare 6111wa tubes for UK delivery for £9.00

Tempting. How many?

What spec 12v power supply do I need?

I use this one: http://www.maplin.co.uk/Module.aspx?ModuleNo=32746

[makaze808]

Hello.

Well I'm towards the end of my build and I'm hoping it sound as good as it looks.

Couple of issues as I work toward switch on.

Does the inductor have polarity?

Regarding the output connections from the tranny is one + going to + on the speaker and the other - going to speaker negative. If so which are which.

The output socket on the box , should this only have the two connections from the output tranny on it or do I link the grounds.

Can I use a resistor across the output socket terminals to lessen the risk of tranny damage should it fire up without a speaker attached, if so what ohm and wattage.

Thanks for help here, I'm hoping to fire it up tomorrow.

[frequencycentral]

Does the inductor have polarity?

I don't think inductors are polarised, if in doubt copy my build(s).

Regarding the output connections from the tranny is one + going to + on the speaker and the other - going to speaker negative. If so which are which.

Yes. And either. I make 2 +ve and 5 ground on my builds.

The output socket on the box , should this only have the two connections from the output tranny on it or do I link the grounds.

I ground the input socket to the output socket, and to the circuit board.

Can I use a resistor across the output socket terminals to lessen the risk of tranny damage should it fire up without a speaker attached, if so what ohm and wattage.

A resistor will affect the ratios if hardwired. You should use a switched socket if you want to do this, that way the resistor is only there if no jack is in the socket. I'd go for say 10 ohm 3 watt or 5 watt. There is probably a scientific way to work it out exactly, but that's not my job......

[Renegadrian]

Here my little DiamondG 1W...

http://www.thepiper.eu/?page_id=129

Finally...
still some little problem to solve but it's ooooook!

Complimenti!!!

[makaze808]

Thanks for the Help FC much appreciated.  Just waiting on the power supply to arrive and a little bit of wiring in the mean time.

[makaze808]

Help for debug needed 

I have no sound at all.

Center tap has 185v

Q1  c 1.2v
      b 0.5v
      e 0.0v

Q2  1 = 1.3v
      2 = 12v
      3 = 0v

Ypurs sincerely,

totally gutted.

[frequencycentral]

Help for debug needed 

I have no sound at all.

Center tap has 185v

Ok, the good news is that your SMPS is working, therefore the issue must be somewhere in the audio part of the circuit. And as the SMPS is working, no need to look at the voltages for Q1 and Q2. So, which layout are you using? One knob or two knob? Bias switch? All jumpers in place? Tubes the right way around (the gap between pins 1 and 8 should face the 555)? Tubes glowing? Rechecked your offboard wiring? Can you post voltages for the tubes?

[Beros]

I have a question.

I'm not really god at the tecnical stuff, but i wonder how much current is running through the trimpot? I have a mini Piher pot that is rated for 100V. Will that do?

[makaze808]

  thanks for the sign posts, got it working, it was the tubes. maybe I missed info on socketing them but i struggled to get them all in tight, I'll prollly soldeer the next. I sort of trusted by build as I checked it more than ever while building it, so tubes became the prime suspect (after clearing all the waffle out of my head). Nice to actually find it first time.

I was blown away with it to be honest, really enjoyed playing it and far more effective as a house amp than 5 watters, which is what i've been using. TOmorrow I'll get chance to whack some effects at it. I took it to a bass players for a few hours and it was really really good, he couldn't stop playing it.

Thanks for bringing this nugget to the diy world.

[frequencycentral]

So glad you got it going! Yeah, I'm still blown away every time I use mine (which is often). I added an on/off/on toggle (to my red one) for the bias mod and really enjoy the clean setting a lot.

Now can we see some photos please!

BTW makaze808, will you be at Wulfrun Hall on December 8th?  

[makaze808]

I can't stop playing the thing.........great through my Marshall 4*12 LOL.  I've just bought an 8inch speaker to hear what it's like through that, thinking of a combo build for my son.

I'll have to try the bias mod, cleaner is prolly good for me as I like to push with pedals. The Harmonic Perculator is having a great time.

Rick I'm finding the amp  too bassy, my very bright rear pickup is kicking butt,  but the neck is too woolly.

Do you think I might of used a wrong value somewhere which is producing the bass? Would an input or output cap help here?


Re Hawkwind

I'm in Manchester Rick so I'll be doing the Manchester Academy and Liverpool too.  I'm a bit miffed with the current line up, last few times I have seen them it's been a bit false. I miss Davey a lot. Still toying with getting to the isle of white..........

Rick do you like the Levitation album, I think Huw is awsome on it and Ginger Bakers drums are so cool. 

[frequencycentral]

It's worth experimenting with the resistor value for the bias mod, I used 2.2k which is really good, but I might try 4.7k next.

If you went by the layout, your C2 and C7 will be 0.1uF. The stock Firefly uses 0.022uF, so maybe try those values to roll off some bass. I like bassy myself.

I just got a Marshall 1936 2x12 for mine.  


Yeah I adore Levitation, saw them 4 times on that tour. My favourite album is Quark, and the whole Calvert period. Calvert had an awesome stage presence on the Hawklords tour.

[Beros]

I have a question.

I'm not really god at the tecnical stuff, but i wonder how much current is running through the trimpot? I have a mini Piher pot that is rated for 100V. Will that do?

Anyone?

[misterg]

I have a question.

I'm not really god at the tecnical stuff, but i wonder how much current is running through the trimpot? I have a mini Piher pot that is rated for 100V. Will that do?

Anyone?

Oh Gawd, another forum to watch....

The 1K trimpot is in series with a 220k resistor (and a 470R resistor) from a nominally 200V supply, so the current (I = V/R) is roughly 200 /221,000 i.e. <1 ma.

Most of the 200V will be dropped by the 220k fixed resistor, so your 100V pot will be fine  

Someone above asked about output impedances... for the original circuit ~25k is reckoned to be optimal (by DougH, the designer), but the schematic was drawn when he was using a lower impedance, hence the confusion over the connection numbering. For the sub-mini version, it's anybody's guess. Particularly as the information on the 7327 is scant.

Incidentally, if you're in the UK, then the RS components 3.5W output transformer works well (better than the 125A IMHO) and is <£10. You need a slightly larger box to fit it on, though.

It's a cute project

(That's my hand in reply#168)