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

[frequencycentral]

At 9V like was talked about though the amp would have "starved plates" and not be as good as it could be imo.

4: Can you just run this at 9v and get rid of the diodes before the MAX 1044?

Yeah - without the MAX though you wouldn't hear anything!

[svstee]

Thanks for the Weber tip Chris, I hadn't looked there.
Have you guys seen this?
https://taweber.powweb.com/store/pdlptsch.jpg
Looks quite useful.

[frequencycentral]

Fellow forum user .Mike has put me on to the Microchip brand 1044 - probably better suited to this project than Maxim's MAX1044, as you could lose the two 1n4148 between the DC input and the 1044:

Price: The Microchip TC1044S is about half the price-- $1.12 for one at Mouser, $0.93 each for 10+.
Supply voltage: The Microchip TC1044S handles 1.5v - 12v, with a 13v max.
Oscillator Boost: The Microchip TC1044S boosts to 45Khz, the MAX1044 boosts to about 30Khz.

Here is the Mouser link:

http://www.mouser.com/Search/Refine.aspx?Keyword=TC1044SCPA

Here's the data sheet:

http://ww1.microchip.com/downloads/en/DeviceDoc/21348a.pdf

Thanks .Mike !!

[svstee]

Right after I bought a few MAX1044's... thats the way it goes, I guess.

[frequencycentral]

Right after I bought a few MAX1044's... thats the way it goes, I guess.

I'm in the same boat right with you - I've got 10 Max1044's! But I run them at 12 volts anyways (don't tell R.G.!).

[~arph]

Just a thought.. doesn't pin 5 output -V supply?

So you get -9V as well.. how about using that as GND so you have an additional 9V.

[frequencycentral]

Just a thought.. doesn't pin 5 output -V supply?

So you get -9V as well.. how about using that as GND so you have an additional 9V.

Well you would also have to use a 10uf cap from pin 5 to ground. And another 10uf cap between pins 2 and 4 -  I'm not sure if this would interfere with the use of pin 2 in the voltage doubling section. Maybe better just to use those two caps (plus two diodes) for another voltage doubling stage and keep it simple?

I'm hoping to finish mine by the weekend. I used six stages of doubling (12 caps, 12 1n4148), and am getting ~70 volts, which is perfect for the 5672. I accidentally ordered twenty 10uf / 100v which are much bigger than I expected - I've used them anyway as there was room in my enclosure, and they look kinda cool anyway. Can't wait to get it finished actually!

[forsakenrider]

Wow. I will definitely build this!

I just wanted to say, I built the Class A amp from JJS with the PSU from the class AB amp:




And its freakin loud through a 4x12... too loud for an apartment.....

[frequencycentral]

Wow. I will definitely build this!

I just wanted to say, I built the Class A amp from JJS with the PSU from the class AB amp:




And its freakin loud through a 4x12... too loud for an apartment.....

Hey forsakenrider that looks great!! Didn't fancy the switch mode PS? I might try this one in my next submini amp, it seems simple and pretty safe too: http://www.ledsales.com.au/kits/nixie_supply.pdf

[Jered]

  Looks great! How does it sound, and how loud does it get?

[forsakenrider]

Yeah the switch mode PSU scared me a bit. It sounds pretty damn good. There is quite a hum and there is nothing I can figure to get rid of it. I Ask the guy that designed it and he said because the submini amps are over driving the power tube the can be pretty noisy.

Its LOUD.

[Ripthorn]

Could you post a link for the project?  I find it quite interesting.

[svstee]

Would 63v electrolytic caps work ok? pretty close to 60v, I know, but 100v are a lot bigger and more expensive.
Also, the 10uf cap before the 1044 doesn't need to be any higher than 12v, right?

[forsakenrider]

Could you post a link for the project?  I find it quite interesting.

this is what I built. http://jjs.at/electronic/class_a_subminiature.html

But I am now going to order some more tubes and try this new design!

[davent]

There's a Trainwreck build happening over at Amp Garage that uses that tube compliment you may be interested in. You need to register in order to see attachments. http://ampgarage.com/forum/viewtopic.php?t=6159

dave

[svstee]

Never mind my earlier post, I found some 10uf 100v electros that are small and cheap here:
http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=020-1296&ctab=1#Tabs
Hope this is useful.

[frequencycentral]

Yeah the switch mode PSU scared me a bit. It sounds pretty damn good. There is quite a hum and there is nothing I can figure to get rid of it. I Ask the guy that designed it and he said because the submini amps are over driving the power tube the can be pretty noisy.

Its LOUD.

Yeah, that fact that the voltage isnt predictable scared me too. The nixie PS I linked to has a regulating mechanism, which seems far more predictable to me. As for your hum - surely it must be a PS issue?

Would 63v electrolytic caps work ok? pretty close to 60v, I know, but 100v are a lot bigger and more expensive.
Also, the 10uf cap before the 1044 doesn't need to be any higher than 12v, right?

The 10uf / 100v I bought were cheap enough - but bigger than expected.

You are correct - the cap before the 1044 can be rated at 15 volts.

[frequencycentral]

Well my chassis is done now, I just have to do the off-board stuff. I'm using SIL sockets as connectors, so the top of the box (containing the input, output, on/off switch, DC socket and gain/volume controls) can be completely removed from the chassis. You can see how this works in the photo showing the transformer connection to the board. Hoping to get it finished today/tomorrow. Hoping it will fire up first time too! I've already tested the PS.

[frequencycentral]

Ok, finished (just about).





Fired up first time - excellent! Though it has some hum that isn't there on the version on my breadboard - strange, I would expect the breadboard version to be noisier. Hmm. Maybe I should use some screened cable. I'll work in it!

I'm also planning to add ultra bright LEDs insid the enclosure, just couldn't get them last time I went to my supplier.

[yertle]

Nice build! I just started messing around with tubes on low-ish voltages, got a boost/od with a 12au7 on 40VDC on the breadboard right now and I also have some sub mini's around (5672, 6088 and 6418) so I might try your murder one amp when I can find the time for it.