Tube boost + overdrive running off a 9 volt battery

[SirElwood]

I just did the vero, I found the schem googling around (don't remember where)

Hi!

Looks very familiar. I draw that schematic and post it in reply #478 (page 24) in this topic. If you found that schematic somewhere else than my page (http://www.tg-music.com) please tell me.

http://www.tg-music.com/EF86.pdf

[Renegadrian]

Hi Elwood - pls PM or write here your complete name, so I can credit you on my layout (also check if I made any errors...) - I don't remember where I did find it, maybe you could try googling it and see for yourself - as you can see it's not the PDF you linked but a cut image of just the schematic.

How does it sound BTW?!

[SirElwood]

Hi Elwood - pls PM or write here your complete name, so I can credit you on my layout (also check if I made any errors...) - I don't remember where I did find it, maybe you could try googling it and see for yourself - as you can see it's not the PDF you linked but a cut image of just the schematic.

I had no luck with google. Need to try harder.

How does it sound BTW?!

It's been five or so years when I build that. But if my memory serves me right, it's very clean, warm and maybe a bit "hi-fi". It does get better with higher voltage and good tube. I used old Tesla EF86. Alot better than new electro haromonix. Svetlana EF86 might be good new tube.

[Renegadrian]

Yeah, I read that altough there are some guitar amp schems around, the EF86 is well known for being clean, so it's mainly used on phono preamps.

edit - I got 3 nos ef86, so they should sound good...I'll try it soon...

[Renegadrian]

I was reading some docs, and this always helpful page here -->http://www.diystompboxes.com/pedals/tubedummy.html

Some pages ago we found we can raise R1 and R2 values, they are the first plate res. (pin 1) and the first grid leak res. (pin 2)
So I ask, would it be useful, asking for more gain, to raise the second plate res. (pin 6) and the second grid leak res. (pin 7) too?

The first cathode (pin 3) goes to ground thru the 50k gain pot and the second cathode (pin 8 ) directly to ground. I assume that if I omit the gain pot, so pin 3 to ground, I'd have max gain?!

Also, the heaters need 150mA - but what about the plate?! I read that in a class A amp at 100V the plate mA is 11.8...
how much current should the plates receive, at 12V and more?! will 30mA be enough?! I want to try it at higher voltages, up to 60V - I guess the polarized cap should have higher V value (not the ordinary 16V, but 35V or more?!)

[DougH]

the EF86 is well known for being clean

Maybe, but the EF86 has a good bit of gain, which is useful for driving a PI/output-stage. See the AC15, DC30, etc.

[SirElwood]

Maybe, but the EF86 has a good bit of gain, which is useful for driving a PI/output-stage. See the AC15, DC30, etc.

True. One of my favourite amps was my "orange AD15" with EF86 preamp. Really nice OD-sound from PI. Shame I never completed that build.

[frequencycentral]

So I ask, would it be useful, asking for more gain, to raise the second plate res. (pin 6) and the second grid leak res. (pin 7) too?

Yes, raising the second plate resistor to say 470K will give a bit more gain, and raising the second grid leak resistor to 1M will too.

The first cathode (pin 3) goes to ground thru the 50k gain pot and the second cathode (pin 8 ) directly to ground. I assume that if I omit the gain pot, so pin 3 to ground, I'd have max gain?!

That is correct.

Also, the heaters need 150mA - but what about the plate?! I read that in a class A amp at 100V the plate mA is 11.8...
how much current should the plates receive, at 12V and more?! will 30mA be enough?!

Have a look at my "Murder One"  amp - I'm running the plates of one dual triode and one pentode from the 60 volt / 20ma output of the MAX1044.

I want to try it at higher voltages, up to 60V - I guess the polarized cap should have higher V value (not the ordinary 16V, but 35V or more?!)

Whatever voltage you run at you should use caps rated higher than that voltage, so for 60 volts you should be using caps rated at 63 volts, or 100 volts to be on the safe side.

[Renegadrian]

OK Rick, after reading your precious post, I am sure that the link and schem I wanted to share could be useful for our tube projects...
check this out...
http://w1.859.telia.com/~u85920178/power/vconv_01.htm

you can have 30mA at 60V, with a circuit that's quite simple to assemble...I already begun, think I am gonna end it tomorrow...

Be sure I'll report it back! 

[frequencycentral]

OK Rick, after reading your precious post, I am sure that the link and schem I wanted to share could be useful for our tube projects...
check this out...
http://w1.859.telia.com/~u85920178/power/vconv_01.htm

you can have 30mA at 60V, with a circuit that's quite simple to assemble...I already begun, think I am gonna end it tomorrow...

Be sure I'll report it back! 

Precious moi?

That's a very interesting schematic you linked to - very similar to the MAX schemo I'm using in many ways.

[Renegadrian]

Yes, my friend...I saw that the max1044 is a little more expensive than 4 trannies (3 bc547 and 1 bc557), so I'd jump on this one if my experiment goes well...

[esdiezy28]

My thanks to all, especially Rick for helping me debug my power supply probs for my stock Valvecaster. I took a cue from the "Murder One" schematic and I had some TC1044s (its an equivalent to a Max1044) around so while I had the whole thing disassembled I thought I'd drop it in and see if it would work. I only used one stage (2 diodes, 1 10uf cap to pin 2, and one to ground) of voltage boosting, and I went up from 12V to 21V. It definately made my pedal louder, and richer sounding. Maybe even less compressed, IMHO. Either way it sounded AWESOME! Just wanted to confirm that the voltage boost from a 1044 will work in pedal setting like the Valvecaster. Thank you!!!

[Renegadrian]

I just built the Marsha Valve by Erik Hansen - altough he provided a vero layout too, I didn't like it and redrew it from scratch.
here it is...



I am not so keen on hybrid circuits, but I wanted to try anyway, who knows...Actually it doesn't give that magic sound that a pure circuit like the Valvy can give...Too many components for a sound that's not so special...Also a well filtered PS is mandatory.
I personally don't like it that much...

[Mtaya]

Hi all 

First of all, thanks a lot for this precious thread & for your help. I'm a beginner in DIY and I've learn a lot by reading your messages.

So, here are few pictures of my "Valvecaster" :

* Circuit



Nota : it's the first time that I draw & realized my own PCB because normally I order them in an electronic shop but it's very long & expensive   

* Face Cover :



Nota :  I have to drill the enclosure


My "little" contribution to this projec :

PCB (size 75*25mm):



Based on this layout :




who became :



Nota : S1-> Input Caps switch / S2 -> Resistors Switch / S3 -> Capacitors Switch


Questions : What kind of switches have you used for thoses because I tink that I haven't used the good one (For S1 I took a DPDT and for S2&S3 I took DPDT) ? 

Cheers,

Taya

[Renegadrian]

Taya, and thx for your contribution to the thread - it's so much apreciated from a newcomer - and hell that graphic rules...Tell me more about those mods, are they so useful?

[Mtaya]

Hi Renegadrian & thank you for your Welcome (we are neighbour because I'm French)

So I've found that schem' on a pdf file found somewhere in those thread, & I've worked on it for having a PCB because I doensn't like to used "drilled sheet"

I've just finished the wiring yesterday evening, so I prefer finish the project before giving my opinion on it 

[Big Dan]

Ok, I think I have gone through most of this stuff. One quick question...I want to build one of these and I can see I'm gonna need to run a power supply with it. Can you guys reccomend a cheap 9 or 12 volt regulated power supply (wall wart)? I run batteries on my pedals so I don't want to have to buy an expensive unit like a PP2. Surely somebody makes a nice cheap 12 volt source.

Thanks,
Dan

[mth5044]

Check out the 1spot 12v powersupply. You can get it at MF and other similar sites and stores. If it's anything like their 9v, it will be very clean.

[castillogm]

Finally I got my tubes from stewmac.com, I bought a pair of 12AT7, which I expect they sound neat. 

I also spend a hard time on finding 12AU7 locally but I finally got 4 from a small repair center (the last four tubes in the whole city!), so I think it would be a great project to build a 2-channel valvecaster with one of each tubes.

But first things first...I'm building the basic Valvecaster, but I have some sort of questions before I start the project this weekend:

1) I couldn't find/get a tube base, so I must solder the parts (or wires) directly to the tube pins... Is there a problem if I do this?  I've never treated with tubes, so I don't know if my soldering iron would damage it.  I have decent skills on soldering, but this is new to me.

2) I've read few pages back that changing the input cap to a lower value would decrease the bassy or boomy sound of the v'caster.  I'm pretending to use a cap selector with a rotary switch, but I'm concerned about how many caps and their values... any suggestions?

Thank you all! 

[biggy boy]

Hi guys!
I have been reading all the pages for the last week and must say you guys are great, lots of info.
I have made a bunch of different circuits and etched several boards, but never anything with tubes!
So much to learn and understand LOL.
Anyway I have most of the parts ready for a twin Valve-caster, just waiting for the Russian tubes to show up.
I'am going to install the new board right into my Amp.
It's a 1981 Univox U65G 50 watt solid state amp.
Hoping to use 30volts at the plate and 12v at the heaters.

Heres a link to an easy to understand site on how a tube works and biasing.
http://www.tubedepot.com/whisbipo.html