Tube boost + overdrive running off a 9 volt battery

[Renegadrian]

Andrew thank you for your kind words, I'm just a noob and I found it a good exercise to do, now I know a little more...
I will build another one, gotta try the inside fet boost!!! 

[Ripdivot]

I have had mine running on 9 volts for at least 20 hours with several different 12au7's. So far I have had no problems. The tubes are all NOS though.

[andrew_k]

I have had mine running on 9 volts for at least 20 hours with several different 12au7's. So far I have had no problems. The tubes are all NOS though.

Yeah, it's probbly the tubes I'm using -- what do you expect for $1 for two off fleaBay

[Aren]

Just built the vero version, still gotta tweak it a bit, but noticed two minor mistakes in it. C3 should be 1uF instead of 1nF, and you forgot to mention that pin 4 should be grounded. It's pretty obvious when looking at the schematics but still..

[Renegadrian]

Aren, thx for pointing out those errors, so here is version 0.5!!! (should be final...)




Hey, post some pics of your version!!! I'll be glad to see them!!!

[Renegadrian]

Based on the Twincaster schem, seen some pages ago and developed by Dano (again) I'd like to show you my Twincaster VERO version...
Here is my vero (should be correct, but hey...)

[Aren]

Will do, as soon as I get it up and running. Right now it doesn't work at all, seems like bad contacts somewhere, but I can't seem to locate the source of the problem...

[Aren]

Since every time i report a non-working build in this forum I figure it out in ten minutes, I'll try this method again...

All I get is some ground hum (which is strange, since it is pretty much star-grounded) but no real signal. Any idea what can be wrong there?
I messed with the connections, and it moved between no sound it all, only ground hum, hum+signal and clean signal. After a while it settled on "hum alone" and I can't seem to find the source of the problem...

[Renegadrian]

Well, it can be a 100's problems...Grounding-some connection you just forgot-bad valve-really bad DC adapter...Dunno...

[Aren]

Well, as expected, it started working 10 seconds after posting 
There is still a ground hum, but that I can fix...

If I only knew what I did to get it working...

[gluedtogether]

I just build version 5 and it works!

Wired direct without a switch, but will add soon. Great layout. I did revert back to the earlier version that had the 8 pin lineup on the board. I just corrected the parts layout. Thanks for putting the layout together.

[Renegadrian]

Oh man, that's great!!! What if I tell you it's my first vero layout I design?!?! I am so happy it worked!!! Time for another beer then!!! 

I just fell in love with those valve projects...I will be buiding marsha, then Orman tube driver and I'll try the Twincaster (valvecaster with 2 valves)

Did you put your creation in some enclosure!? Pics are welcome, as for Aren!!!



PS a big thank you goes to Dano, he started it all...

[gluedtogether]

Just wired up the switch and everything works great. I don't have a 100k pot for the gain as I didn't have any 50k. I want to see if I can tame the gain a bit. Its capable of some decent amounts of gain. I am a couple weeks away from creating an enclosure. I want to come up with something good for my first tube build

Echo your sentiments, Thanks to all on the thread.

[Aren]

It's still VERY unstable (I'm beginning to think the volume pot should be replaced), but here's the pic:
http://picasaweb.google.com/lh/photo/gSqPT9t6cpgypPkAKZsVdg

It's my first attempt to use the "dark t-shirt transfer paper" (with the aid of my beautiful talented wife  ).
The actual box was painted with regular acrylic paint and finished with water-based clear coat.

[Aren]

This is getting weird.
I replaced the pot, and it did improve the stability issues. Worked great, only had this annoying buzz in the background. Since I eliminated the possibility of a ground loop, I decided I would try and stabilize the power supply by adding a 180ohm resistor in series with the DC jack. It stopped working altogether, so I measured the power at the DC node. It was 2.53V!  Once I disconnected the resistor from the vero, and measured it with no load, I got 15.3V, so the resistor is fine.
Any thoughts?

[Caferacernoc]

"Just wired up the switch and everything works great. I don't have a 100k pot for the gain as I didn't have any 50k. I want to see if I can tame the gain a bit. Its capable of some decent amounts of gain. I am a couple weeks away from creating an enclosure. I want to come up with something good for my first tube build"


To tame the gain I would lower R2 and R3. 220k and 100k seem pretty high for a low voltage circuit. Even in a regular high voltage amp the normal value is just 100k. So maybe cut them in half.

[snoof]

if you bring down that 220k to 100k it will def lower the gain a bit.  I built mine with both plate r's at 100k.

[gluedtogether]

Thanks for the replies. I may try and add a toggle switch to have the higher gain setting available. I will give that a shot and report back

[andrew_k]

I want to see if I can tame the gain a bit.

hehe, I did the complete opposite. A 1M gain pot allows massive, saturated gain. A little mushy in the bass frequencies, but pretty cool. I'm considering putting a "more" switch in, whereby it adds a resistor in series to the regular gain pot.

[Renegadrian]

Going from 50K to 1M...Hell, now that's a big difference!!! So it gains more gain?! 
And for what I understood...higher resistance value = more gain?
gotta try this pot change...what about 100K or 500K???