6au6 pentodes in push pull clean low watt practice amp. uses 1363 smps and 9v

[zambo]

<iframe width="420" height="315" src="http://www.youtube.com/embed/cKKMd11c3kc" frameborder="0" allowfullscreen></iframe> Just thought i would share this with the tube heads on here. 6au6's are cheap and sound sweet. OT is a hammond 125c . smps is the taylor 1363. I actualy drew a schematic thats probably crappy and wrong but will post it for proof reads here in a while. Could be made small by a couple guys with real talent. 

[blackcorvo]

Just a little correction: To post embedded videos from Youtube, just get the link to the video and click on the little youtube icon over the line with all the emoticons when you're writting a message.
Put the link between the code, like this: [ youtube ] yourvideolinkhere [ /youtube ]
It will look like this:

This is why I'd recomend to always preview your message to check if everything is ok.

Anyway, about the amp...
Awesome project! PLEASE, post the schematics! I really wanna see what you came up with.

I'd love to try it out myself, but I only have one 6AU6 here ATM.
I though of maybe trying something similar to this some time ago, but using 6AW8's, ECL84's, or other small triode-pentode tubes. I dunno why, but I really wanna try something that sounds good with these "2 in 1" tubes, if possible with clean and dirty sounds, but with less than 5w (I realized I don't need that much volume here, specially when people complain when I play my strat unplugged lol).

So, for now, I'll be waitting for more info on the circuit. I might not be able to really design anything by myself, because I tried reading about tube theory before, and all I got out of it was confusion and a bad headache. But I still can draw and write down my ideas.
Now I'm gonna let the gears working, and try to get a nice night of rest. I should be doing this long ago, but my brain never shuts up...

[Jaicen_solo]

That sounds awesome, definitely looking forward to seeing a schem.

[iccaros]

nice......

[harmonic]

Really nice! Surprised how decent it sounds with such a shallow cab. Really nice ring to it. Good job. :-)

[Tacoboy]

Ow yes! Sounds nice!

[Zipslack]

Nice tone...is that a bathroom/reverb hall?  j/k - I really liked it.  Reminds me of old Silvertone or Alamo amps.  Do feel free to share the schem 

[iccaros]

I know Greg is busy, so I attempted to guess what he made.. Note his is most likely wrong.. But with a little input we may get it... I am not sure of the voltage divides as I do not know the current..

[John Lyons]

Cool amp Greg.
Looking forward to seeing what you have in there.
I dig the cabinet, funky and funk-tional. 

[zambo]

@ Blackcorvo -  Thanks! I will try and get it right next time   I have not been on here enough!

@ Iccaros - Your close!



as always, look for errors. I am not really a schematic guy ( overstating....?) I kind of build as I go etc. so errors and possible dangers abound  

I used 4 IN4007 diodes in series off the 9 volt supply to get roughly 6 volts DC. I think 6.1 is what i measured. not sure of the other voltages but the dropping resistors in the power supply are 100ohm. the preamp tube is a 12au7. tried others and they got more bite but I got some weird over distorting type of stuff happening. changed a bunch of values inside and used the 12au7 and it stopped the bad sounds. schematic reflects the changes. please add corrections as you see them and warn of potential hazards for others if you will  

Thanks in advance for input, advice and corrections. use and share at will with whomever you will. post where you want if you like god bless etc.

[zambo]

Thanks John! 

[blackcorvo]

@ Blackcorvo -  Thanks! I will try and get it right next time  I have not been on here enough!

No problem!

Just one thing bothering me on this design. I mean, I don't know anything about how to design Push-pull circuits, but it looks like you wrote 47R as being the 6AU6's cathode resistor... and that value just sounds way too low to be right... at least to me.
How hot did you put the plates to work?

[Jaicen_solo]

Ok, the question I have is how does it sound when you overdrive the phase inverter?
I've been looking to build a super-low watt Plexi to finish off my Jimi fanboy gear. I was planning to use a pair of EL84's, as i'm running an SE El84 at the moment, and I like the sounds I can get from it.
I was thinking that I could squeeze the Plexi front end onto this and get close to that Plexi sound i've been looking for.

[petemoore]

  Nice amp dude ! !
   2w is a very nice grind, easy to get distorting in a 'room' and easy to mic up too, valuable tool IME when voiced similar to a big amp...for tweeking/voicing efx. settings/circuits to make nice distortions, and use in a 'room'...indespensible.
   When plugging 'that' output [stompbox pedal signal] into a more powerful amp/speaker rig, a simple volume and treble readjustment is all that's needed to compensate and make a very similar tone but louder [bass extension with larger cabinet and other caveats apply, point being it's easy to compensate and swap big/small amps when they're both able to distort and are voiced similarly].
  This is a nice net-share, thank you for posting, the supply and hardware [tubes, tranny's speaker etc.] make a very nice DIY amp circuit selection for builders into tube-output distortion.
  After owning/trying them, I found out 'they' were right, I didn't need [and couldn't actually ''use'' Plexi-distortion], I just needed a nice little tube practice amp to crank.

[amptramp]

The only issue I see with the schematic is that the cathode output of the phase splitter applies more signal to the bottom output tube than the top one.  The drive to the bottom tube should come from the junction of the 500K/1.5K/47K resistor because the same current flows through both the plate 47K and the cathode 47K resistor which gives the same drive (but of course, in the opposite polarity).  Having 47K on the top and 48.5K on the bottom with the same current flowing through it gives more drive to the lower pentode.

BTW, what output transformer are you using?  I imagine the plate-to-plate impedance should be fairly high.

[iccaros]

@Zambo
I will redraw tonight to match your hand drawing

@amptramp

It looks like the same transformer a firefly uses, 22K

[Zipslack]

Just a quick note...you can use 12au6 directly in place of 6au6 and then you can use the same 12.6V heater voltages as the 12au7.

[iccaros]

or use the 12au7 in 6.3 volt heater.. as most amps do

[Zipslack]

Yeah, but I've got a stash of 12V - 15V wall warts for 12.6 volt regulated output...besides, I like the lower heater current (even though I realize power is the same).  It just seems easier to find beefy 12V wall-warts compared to 9V warts with enough power output.

[iccaros]

any way you want.. I have some Russian versions that are 6.3 volt only.. so I am working on that ideal..