New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage

[frequencycentral]

So Rick, are you using the switching supply schem from the JJS place?

What - in the next design? No, but similar - planning to modify this one for more volts, it's more stable, as the BC547 regulates the output: http://www.ledsales.com.au/kits/nixie_supply.pdf

[petemoore]

  that sure looks like a neat workaround !

[jacobyjd]

So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?

...or am I crazy? 

I know it gets away from the original intent of the project, what with the whole submini focus and all, but I'm just looking at what I have on hand

[frequencycentral]

So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?

...or am I crazy? 

I know it gets away from the original intent of the project, what with the whole submini focus and all, but I'm just looking at what I have on hand

Yup  - that should work just fine - and the 12AU7 heater would draw less power than the 6111 heater. Just wouldn't be quite as small.

[jacobyjd]

fantastic.

I'm thinking of using a 1590bb as the chassis--I don't really need it to be super small. my other alternative would be to build it into a combo setup. I may make the BB-sized 'head' first, then remove the bottom plate and screw it into place in a cab once I get done with tweaking.

Keep up the good work with these designs, man, I know plenty of people who are looking for a good sound from low-power recording amp.

[svstee]

My idea for the power stage (or whatever you want to call it) :



I'm sure there are more effective ways of doing it, maybe Perf with the diodes mounted on the underside like you mentioned doing.

[petemoore]

So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.

[frequencycentral]

So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.

I think jacobyjd is saying that he's using 12 volts for the 12AU7 heater but 70 volts for it's plate, which should operate the same as the 6111. Are you thinking of 12U7 space charged tube (which I'm guessing wouldn't work in this application)?

[frequencycentral]

I'm sure there are more effective ways of doing it, maybe Perf with the diodes mounted on the underside like you mentioned doing.

+1, it can be made a lot more compactly on perf. I'm not a fan of vero - I find it limiting because you have to work in one plane, and cuts in the track cost space. Perf lets you work outwards in any direction, and no need for cuts.

[jacobyjd]

So say I wanted to do this build using a 12au7 in place of the 6111. I could pretty much do everything the same, just using the full 12v for the 12au7 heater, right?
  12au7 for starved plate...has been done, that is very starved, starting with a tube designed for 12v supply...will operate differently.

I think jacobyjd is saying that he's using 12 volts for the 12AU7 heater but 70 volts for it's plate, which should operate the same as the 6111. Are you thinking of 12U7 space charged tube (which I'm guessing wouldn't work in this application)?

Right--from past discussions I've read, it appeared that the only functional difference between the 12au7 and the 6111 were the heater voltages. I'd still plan on running the 12au7's plates at 70v.

[frequencycentral]

Finally got around to doing a soundclip: http://www.aronnelson.com/DIYFiles/up/Murder_One.mp3

Signal path:

Squier Telecaster Custom (HB)  >  Murder One (cranked)  >  12" / 8 ohm speaker  >  Shure SM58  >  Event Echo Gina 24 soundcard  >  Wavelab

No other processing.............except when I stomp on the Valvecaster half way through.........you'll know when.

[kurtlives]

NOTE ^

The 60v you get out of the transformer would be AC, not DC, which, after rectification, would actually give to higher than 60vDC (~ 83vDC). You may want the added voltage, but if you don't you could choose a different transformer.

Determine the HT you want, and then add 5 volts to that to get your target DC voltage (HT + 5v = V_t)

Once you have target voltage, divide it by 1.414 to get your secondary AC voltage you need to be supplied by the transformer (V_sec)

Once you have your secondary AC voltage, use this ratio to determine the transformer you should use.  (120v / 'x') = (V_sec / 12v)  where x is the desired value of the transformer secondary

For example, if you wanted an 78v B+, your V_t would be 83v. This divided by 1.414 would be 60v. Plugged into the equation this would read (120v / 'x') = (60v / 12v)   which when solved would show a 24v secondary. So you would use a 120v to 24v transformer (120v is always the primary).


Zach

Would you get that 78V DC B+ if you wired the 24V side of the transformers to the 120V IEC jack. The 120V winding of the transformer then puts out 78V DC?

[frequencycentral]

Here's the start of another Murder One that I'm building for a friend:

[Jered]

  Rick, the murder one sounds good and with the valvecaster it gets a great fuzz sound.

[frequencycentral]

 Rick, the murder one sounds good and with the valvecaster it gets a great fuzz sound.

Thanks Jered - did you do anything with your nixie PS yet?

[frequencycentral]

Another "Murder One" built for my forum buddy sweetwilly. A much tighter build than my first. It uses a 7327 instead of a 6111, which give a bit more gain. The transformer is a Hammond 1750A, which is their equivalent to the Fender reverb transformer. The PS supplies a few more volts than mine, (more efficient caps perhaps?) so it's a bit louder - damn!

[frequencycentral]

I did a perf layout for the power supply, which you can find here.

[frequencycentral]

[sweetwilly]

no words!!!

[frequencycentral]

no words!!!

Did I mention that it lights up in the dark? Wanna see a photo of that too? I'll post one later when it's dark!