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

[tgorman]

I have been following this post for a while, I finally assembled my build of Murder one today. It was my second build not using a kit. Unfortunately I am getting no sound out of it. Got a bit of checking to do to get it going. Thanks Rick for making this available for others to build. I can't wait to get it going and try it out. I guess I should check the voltages on the ICs and go from there. I already double checked the off board wiring and took a look for solder bridges and so far it looks good. Here is a shot of the outside, I could put up a gut shot if anyone is interested.

[frequencycentral]

^^^

Looks excellent! But the pentode looks like a 5678 not a 5672, IIR the filament connections are reversed ie pin 3 = F-, S, G3; pin 5= F+, S, G3. I'm not sure if that makes any difference in practice but it may , just may, be the issue. If that is a 5678 I'm not sure how far else it's spec varies from 5672.

[tgorman]

Yep it's a 5678. Not what I ordered but that's what I got. I will try replacing it with the proper tube. Thanks for the tip! I cant believe I never even checked it before I put it in. Glad I used sockets. By the way how could you tell just from the photo? Sorry I'm a bit of a noob.

[frequencycentral]

By the way how could you tell just from the photo?

Damn this x-ray vision! Actually 5678 are grey like yours, while 5672 are clear glass. I have plenty of 5672 if you get stuck.

[tgorman]

X-Ray vision, wish I had that! Told you I was a noob. I have some of the 5672s on their way, thanks for the offer though. By the way my first non kit build way your Promiscuous Girlfriend. It's my favorite overdrive! That one worked right out of the box. Thanks for the help, God knows I need it.

[frequencycentral]

By the way my first non kit build way your Promiscuous Girlfriend. It's my favorite overdrive! That one worked right out of the box.

Cool! Post some photos in the Promiscuous Girlfriend thread! And we wanna see guts of the Murder One too....

[tgorman]

You got it. Look for them tomorrow, its off to bed now so that I can go to work tomorrow to make money to pay for parts.
Thanks again for the help!!!

[tgorman]

Okay you asked for it, here it is a gut shot of my Murder One build. Please be gentle it was only my second time.

[Plan B]

Shit!  I got the same exact tube!  Let me guess, small bear and made by raytheon?  Thanks for catching this--I would've pulled my hair out and probably smashed it with a hammer.

[tgorman]

Well I don't want to bad mouth them, but yes. They also sent me a free one when I brought it to their attention. I have always had very good service from them.

I have not yet received my new tubes yet so I still can not confirm that it is what is wrong with the one I made. There a lot of other things I could have done wrong along the way. I only just started doing this recently. I only even got a soldering iron so I could put new pickups in my guitar so I don't have a huge knowledge base to work from. I am however enjoying the learning process very much.

[mydementia]

It's ALIVE!!
What a fun little amp build!  Reminds my of my 30V Sophtie project (http://dbx-fx.webs.com/30v.htm) only about 1/4 the volume!  
Now to incorporate booster, trem, and all the other snazzy mods - then box it up...
Thanks for the great project Rick!!
The V5 PCB works just fine in case anyone was wondering.
EDIT - looks like the gallery here is having fits with my image... let's try this one...

[frequencycentral]

^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?

[tgorman]

Bring it on!

[dimi3]

^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?

Any news on this one? I finished first MO and its great, I still have some tubes left, and want to try another one with fancy enclosure and everything

[frequencycentral]

^^^ No pics?

I just finished a new 'modder's delight' layout which includes cathode resistors and bypass caps as well as grid stoppers. Anyone interested?

Any news on this one? I finished first MO and its great, I still have some tubes left, and want to try another one with fancy enclosure and everything

The layout and accompanying schematic are done, I just need to breadboard it again in order to make some build notes. Within a week. 

[dimi3]

wow, thats great, I will wait for it, when desinging PCB for it, any chance to do a little wider PCB traces?
thanks for sharing.

[frequencycentral]

....when desinging PCB for it, any chance to do a little wider PCB traces?

Way ahead of you! 

[frequencycentral]

The original Murder One was 'baby's first amp'. I've learned a lot since then and the design has gradually changed over time. This one is a major upgrade, and now it's looking much more like a serious amp. What's changed:

• Input section is different (R6/R11), the original was more like what you'd see in a pedal.
• Preamp stages rebiased with 47k anode resistors (R1 and R2) and the addition of cathode resistors and bypass caps (R9/C19 and R10/C15)
• Grid stoppers added between stages (R12 and R13), R12 is essential, R13 is optional and may be jumpered instead
• New schematic with component values matching the...
• ...new layout
• Tweakable values are asterisked *
• Fatter traces and pads on the layout - for a fatter sound!

The result of these additions is that the anodes are running at much higher voltage, the clean sound is much better than it was - very usable now, and the cranked sound is fatter and has more body.

As this is the Modder's Delight version, any tweaks to suggested values should be considered in conjuction with this article: http://www.diystompboxes.com/pedals/tubedummy.html

I have verified the new layout onto perf, it works really well. If anyone feels like etching me a board or two I'd be proud to accept them!

[kurtlives]

Cool, you shouldn't need C17 though. All DC voltage is being blocked by C14.

Maybe you have it there for the bias voltage you are generating with the MAX thing.

[elshiftos]

A couple of questions if I may....
What is the HT voltage, and is the OP transformer the same as the fender reverb type?

Thanks