Tube boost + overdrive running off a 9 volt battery

[frequencycentral]

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.

I wouldn't do that - you'll have a hard time mounting the tubes to the enclosure without sockets. And what if you need to change a tube? They shouldn't be too heat sensitive though. Better to get some sockets - try ebay.

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?

0.033 or 0.022 will be less bassy.

[biggy boy]

What do you think about putting a cap across VR1? Apparently it will help to increase the gain.
It would go between pin 3 and the ground.

Glen

[biggy boy]

OK I have the Twin Valvecaster board etched and ready to be drilled . It's been a couple of years since I made one, had to re figure out how to do it
The two tube sockets will not be mounted to the board.





Glen

[castillogm]

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.

I wouldn't do that - you'll have a hard time mounting the tubes to the enclosure without sockets. And what if you need to change a tube? They shouldn't be too heat sensitive though. Better to get some sockets - try ebay.

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?

0.033 or 0.022 will be less bassy.

Thanks, Freq!  I started the project this weekend, and I used some sort of connectors to attach'em to the tube while I find a socket. For my disgrace, I didn't get nothing but a terrible hum.  The tube was lit, but no sound came out...  I hope I come with better news next week.

[biggy boy]

COOL got my twin Valvecaster working
I got my first ever DIY tube preamp working, it sounds good!
I built it into my 50 watt solid state amp. The amp was way to clean, could not get any overdrive or distortion on it before adding the twin Valvecaster.
But now it's got tons of overdrive 

I didn't bother adding the out put volume control but I think I'll add it in.

Thanks guys for all the great info. I would not have been able to make the preamp without this thread!

Glen

[svstee]

I'm sure this has been covered but I couldn't find it. I want to build a valvecaster running off 9v using a subminni 6111 tube, of which I have 40, as opposed to a 12AU7, of which I have one, and it is being used. The pinouts are different, yes? what changes do I need to make?

[frequencycentral]

I'm sure this has been covered but I couldn't find it. I want to build a valvecaster running off 9v using a subminni 6111 tube, of which I have 40, as opposed to a 12AU7, of which I have one, and it is being used. The pinouts are different, yes? what changes do I need to make?

But you can use a 9 ohm / 1 watt resistor to drop your 9 volts to 6.3 volts for the heater instead of using the LM317 arrangement. A 10 ohm / 1 watt resistor would give you 6 volts, which is still within the tubes spec.

[biggy boy]

OK need some help with grounding.
I'd like to improve the grounding on my printed circuit boards.
I want to start using ground planes to help reduce noise.
To go one step further Id' like to have two ground planes. One audio signal GND plane and one power GND plane.

I've included a schematic (not mine)
Can someone point out which grounds in the schematic are audio signal GNDs and which ones are power GNDs?



Thanks
Glen

[Jered]

  Read RG's star grounding article over at  http://www.geofex.com  it has all the info your looking for.

[biggy boy]

  Read RG's star grounding article over at  http://www.geofex.com  it has all the info your looking for.

Hi Jered thanks for the link
Lots of great info on that site. I book marked it!
Yup well aware of the star ground principle.
I'm looking for different info thou.
I want to take it further and separate the signal grounds and the power grounds in a tube circuit. tubes are new to me and I'm trying to learn what portions of the circuit is power and what is signal. Ground planes are large areas of copper on a printed circuit board used as a common ground point the star. So I'm looking at basically having
two ground planes (stars) on the circuit board. One for power GNDs and one for signal GNDs. The two planes are then joined with a trace and then to the chassis.

I just need help figuring out what the GND points are in the diagram I posted.

My guess would be:
signal GND  R1, R3, R6, R8, pot 4
power GND pot 1, pot 2 and all the GNDs connected to the cathodes.


Glen

[schlendrian]

hey everybody,
any news on a current working tubecaster project with a EF86?
I'm highly interested in soundsamples, bugs, issues, suggestions and so on with this one.
I'm planning to get myself a 48V DC power adapter to have higher anode voltage and get the 6.3V with the usual LM***
thoughts on that?

alternatively I thought about getting more voltage from a wall wart with this schematic:


help is mucho appreciated,
greetings from hamburg, germany

[Renegadrian]

Hallo schlendrian from Renegadrian and

I only know about this EF86 project, not a Valvy based one...


The image you tried to post don't show - try to post it again
I used a voltage multipier, so I'd go with a common wall wart at 12V, a 7812 or 7806 for the heaters and the multiplier (the one I build gives out 50V)

[schlendrian]

hey there! yeah I saw that schematic recently which got me pretty excited about this project.
since the EF86 would sound significantly better and would've had more distortion with more voltage I thought about a power plug with already
48V 0,5A directly to the plate and then generate the 6.3V for the heating, can I do that with a 7806 as described in the schematic you posted?
would be this one:


here is the alternative with a 6V wal wart transforming the voltage up to about 200V for the plate:


Pollin is a special shop over here, so don't worry about the numbers.
what do you think about it?

[biggy boy]

Hi
You had mentioned about dropping the voltage from 48 volts to 6.3 using a regulator!
from 48v to 6.3v would be asking alot from one regulator.  It would need a big heat sink to dissipate the heat coming off of it, plus I think they have a voltage max of 40V.
I guess you could put a resistor in series with the regulator to create a voltage drop.  But it would have to be able to also handle the heat it would need to shed. 3 or 5 watts??

Glen

[frequencycentral]

I guess you could put a resistor in series with the regulator to create a voltage drop.

Glen

213.5 ohm / 8.54 watt @ 200ma

To use a voltage drop resistor to drop 42.7 volts (48 - 6.3) it would have to be 213.5 ohm / 8.54 watt. That would be one huge resistor. Does such a resistor exist even?

42.7 / 0.2 = 213.5 (ohm)

42.7 x 0.2 = 8.54 (watt)

I think when dropping this much voltage you should be thinking transformer.

[biggy boy]

I guess you could put a resistor in series with the regulator to create a voltage drop.

Glen

213.5 ohm / 8.54 watt @ 200ma

To use a voltage drop resistor to drop 42.7 volts (48 - 6.3) it would have to be 213.5 ohm / 8.54 watt. That would be one huge resistor. Does such a resistor exist even?

42.7 / 0.2 = 213.5 (ohm)

42.7 x 0.2 = 8.54 (watt)

I think when dropping this much voltage you should be thinking transformer.

If you put the resistor  in-front of a regulator you would  not have to drop the voltage down to 6.3v just drop it down to say 12 volts feeding the regulator.
You would still need a heat sink on the reg.  48 -12 = 36 / .2 =  180 ohm    36 x.2 = 7.2 watts     LOL  it would still be a big ass resisitor.

Glen

[frequencycentral]

That would be one huge resistor. Does such a resistor exist even?

LOL  it would still be a big ass resisitor.

Second item from the bottom, 220 OHM 10 WATT 10% CERAMIC BLOCK RESISTOR-SIZE: 1-7/8"L x 3/8"H x 3/8"D @ $2.50, http://www.electronicplus.com/content/ProductPage.asp?maincat=RE&subcat=REG

[biggy boy]

Something else to take into consideration.
Manufactures usually rate their power supply voltage output at there full amp rating. The voltage at no load and at half the specified max load would be higher.
This should be considered when selecting the size of the resistor. The open  no load voltage I would guess to be someware around say 52 volts or maybe a bit more??
With a 200 ma load and the load of the tube. the voltage would still be higher then the 48 volts.

Glen

[firethorn]

Help!

I've followed the schematic located in the first post or on beavis' page (the normal one, not the pcbless, etc) to the letter in my implementation of the valvecaster. Discovered a few issues like the gain pot being wired the wrong way round (yes, following the schematic visually, how lazy of me) and the same for the tone pot, both of which have been fixed.

The main problem is that I don't hear much difference in sound. In fact, with the pedal engaged at full volume and gain, the output volume is softer. It's so much softer that putting my gain pot slightly below full will result in no sound. From my understanding of the schematics, even if the volume pot happened to have been reversed, it would make no difference to the sound.

All resistors and solderpoints have been checked. I can't check the caps but I trust em. Except..... For axial electrolytic caps, the arrow points from +ve to -ve right? I always have doubts when it comes to caps.

I have slight hum when I put the wires connected to the tube socket so close together but other than that, it's fine.

I need help! It's unholy for a overdrive pedal to sound softer than it's bypass!

[frequencycentral]

Help!

I've followed the schematic located in the first post or on beavis' page (the normal one, not the pcbless, etc) to the letter in my implementation of the valvecaster. Discovered a few issues like the gain pot being wired the wrong way round (yes, following the schematic visually, how lazy of me) and the same for the tone pot, both of which have been fixed.

The main problem is that I don't hear much difference in sound. In fact, with the pedal engaged at full volume and gain, the output volume is softer. It's so much softer that putting my gain pot slightly below full will result in no sound. From my understanding of the schematics, even if the volume pot happened to have been reversed, it would make no difference to the sound.

All resistors and solderpoints have been checked. I can't check the caps but I trust em. Except..... For axial electrolytic caps, the arrow points from +ve to -ve right? I always have doubts when it comes to caps.

I have slight hum when I put the wires connected to the tube socket so close together but other than that, it's fine.

I need help! It's unholy for a overdrive pedal to sound softer than it's bypass!

Please post voltage sfrom each pin of you tube!