Firefly amp Running off charge pump (555 SMPS) . HELP!

[thedoc115]

I've made the 555 smps that Frequencycentral designed and used it to power a 12au7 wired like the output of a firefly amp and I'm getting sound but its super quiet.

I use this output transformer http://www.ampmaker.com/store/4W-push-pull-output-transformer.html

any help is appreciated.

[psychedelicfish]

Voltages? Links to schematics? Pictures? We know almost nothing about your problem from what you've told us, so we won't be able to help unless you give us some more information

[thedoc115]

this is the schematic. http://ax84.com/media/ax84_m276.gif

I made the power amp which is every thing past R12

as for voltage I've tried every thing from 100-280v

and its drawing about 10ma.

[psychedelicfish]

I take it you included R12? The power amp doesn't provide much voltage gain, so you really need the preamp to provide the power amp with enough signal to make good use of. You should either include the V2 sectoin, or you could try replacing the 12AU7 with a 12AT7, which has far more voltage gain, but can still drive the output transformer

[thedoc115]

Yes R12 was included I tried it with a 12AT7 and it was a little bit louder but not much ( my guitar strings are louder).

I tried giving the the tube more signal by using a tube screamer and it made it louder but not by much.

I have a smokey amp and its louder than this at the moment.

*edit* I'll make the preamp and see if its any louder.

[psychedelicfish]

The preamp will give you more volume than the TS, which can do about 1V p-p, while the preamp will give you far more

[PRR]

> every thing past R12

You need over 10 Volts of signal there to get the full power output.

Guitar signals are more like 0.1 Volts.

You need a LOT of gain in front. More than most "boost pedals".

Really, the best thing at this point is to build the V2 stages. That WILL give full output from guitar-type sources.

Alternatively: derive a 50V power supply and use two JFETs or a hi-voltage opamp chip to get gain over 100. However since you *have* a 250V supply, and heater power, and the V2 stages use a small fraction of the V3 stage, another bottle is probably the best path.

That V1 stage looks over-the-top to me. Not a bad idea, but not as essential as the V2 stages.

[thedoc115]

I think I'll build the v2 stage and see if its any louder.

As for the SMPS does the maximum current draw increase if the wallwart is say 3A rather than 1A.

[Striker Amplification]

CHECK all of your cathode resistors, if ANY of the preamp valves are in fact overbiased you will get a smaller negative electron flow from the cathode to the anode/plate, causing the tube to amplify less, this goes for the power section as well.

[Scruffie]

I did what you're doing with a MAX1771 power supply with the 2nd preamp tube, worked great!

Check the SuperFly thread for the schematic/PCB/info.

[thedoc115]

I did what you're doing with a MAX1771 power supply with the 2nd preamp tube, worked great!

Check the SuperFly thread for the schematic/PCB/info.

What kind of volume level did you get out of your amp.

[Scruffie]

I did what you're doing with a MAX1771 power supply with the 2nd preamp tube, worked great!

Check the SuperFly thread for the schematic/PCB/info.

What kind of volume level did you get out of your amp.

Bedroom levels, 1/2 - 1watt I guess.

[thedoc115]

Should have this finished by the weekend, I'm just waiting on some small parts. 

[DougH]

I did what you're doing with a MAX1771 power supply with the 2nd preamp tube, worked great!

Check the SuperFly thread for the schematic/PCB/info.

What kind of volume level did you get out of your amp.

That question makes no sense without the context of the speaker you are using.

[Scruffie]

I did what you're doing with a MAX1771 power supply with the 2nd preamp tube, worked great!

Check the SuperFly thread for the schematic/PCB/info.

What kind of volume level did you get out of your amp.

That question makes no sense without the context of the speaker you are using.

Indeed, I did try it through a futurlec 3w rectangular speaker, that was fun and toy sounding. Still had a decent bit of volume on tap though if I recall.

[thedoc115]

Ok, I've made the V2 stages but its still really quiet.   what should I check.

Checked the wall wart and only seems to put out 11.88v (the heaters are also only getting 11.88v) , should that matter?  

[psychedelicfish]

How much current can your wall wart supply? The heaters of 12A*7s will pull 150mA at 12.6V, and 300mA at 6.3, so your wall wart will need to be able to do 300mA and whatever the rest of the circuit takes, but you generally should be able to supply at least twice the current you need, because the voltage tends to sag when you pull close to the max current. Check voltages have you got on the valves. Check and double check the wiring. Check the AC voltage coming out of the V2 stage when you strum hard into it. What speaker are you using? What valves are you using?

[thedoc115]

How much current can your wall wart supply? The heaters of 12A*7s will pull 150mA at 12.6V, and 300mA at 6.3, so your wall wart will need to be able to do 300mA and whatever the rest of the circuit takes, but you generally should be able to supply at least twice the current you need, because the voltage tends to sag when you pull close to the max current. Check voltages have you got on the valves. Check and double check the wiring. Check the AC voltage coming out of the V2 stage when you strum hard into it. What speaker are you using? What valves are you using?

My wall wart can supply 3A, the speaker is an 6in 8ohm 10w and the V2 valve is a 12ax7, V3 is a 12au7.

I think I'll try some other tubes just in case.

The plates of V2 are getting about 140v

The output in Vac from V2b is about 20v with a good strum

I actually used this preamp http://www.muzique.com/news/images/Epi1.gif
everything thing up to C2.

[thedoc115]

Tried some different tubes but still no difference  

What am I doing wrong

It would appear that the tubes are drawing 280ma (high voltage) now I'm really confused  

on the output transformer (output jack) I'm only getting about 1-2Vac.
Could my output transformer be bad.

[thedoc115]

ITS ALIVE!!!!

I'm the biggest arse in human history...

R13 on the firefly schematic should be 440 ohms not 470k

Case closed...

it works and is very loud through a 1x12 cabinet.

pictures to follow soon....