Tube boost + overdrive running off a 9 volt battery

[sonbone]

I built a subcaster with 6111 tube using a V+ of 24 volts.  More headroom for pedal steel and Telecaster guitar with high output pickups.  I was looking for a clean sound to warm up the sound of my transistor amps. Tried several voltages on the breadboard, 12V, 18V, 24V and 33V.  Liked 24V the best for my application.  For the power supply I built a separate "brick" with 2 mouser trannies.  Mounted 5 pin DIN connectors to the power supply and the pedal and use standard midi cable for power transmission.  I think this setup might also work well with the previous schematics using 6021 submini tubes, but I don't have any and I haven't tried it.  Links to pics and schematic below.  Sorry but the gut shot is a little out of focus, but you can get the idea.

[Renegadrian]

Albot, I tried several different brands, every tube has its own light, going from a dim light to a bright light...So that shouldn't be a problem...I wonder why it doesn't work...



Sonbone, great work!!! I like your pedal, how's its sound?!

[Jered]

  Sonbone, I agree, at about 20-22 volts you can start to hear what you would hope to hear from a vacuum tube circuit, if that makes any sense.

[Albot]

Mine light up with a bright glowing white/yellow light.. I think im simply cursed! 

[Albot]

So when i try to run only the heaters out of the circuit, 12 volts make the entire heater pipe glow orange since i've never seen that in pictures i guess it's bad.
Oh im so worried, irritated and frustrated! dont wanna break my new tubes!
Especally since I wouldn't learn anything from it except that im cursed.

[Renegadrian]

Albot, the 12au7 is made to run the heaters at 12V - so don't worry about that...

[sonbone]

This pedal sounds really smooth, adds quite a bit of warm to transistor amp.  My computer with recorder is down right now, so I can't record samples.  I have a version on my breadboard with both cathodes bypassed with 22uf caps and biased with 1.5K resistors.  Gain control is through 500K pot between stages. It's similar to Real McTube.  It has a much more aggressive sound since there isn't any negative feedback going to the cathodes.  I like the circuit on the breadboard better with my stratocaster.  Also sounds much better at 22V and above.  Two reasons I settled on 24V.  (1) 7824 voltage regulator in power supply filters better than just using rectifier and caps (which gives me about 33V with 24V ac transformer). (2) To me the circuit sounds best with volume control as close to wide open as possible.  Above 24V the gain is so much that I really have to cut back the volume.  I tried a voltage divider at output, as in Real McTube, but I don't really like that any better than just cutting back the volume.

[intricatecode]

hi guys 

been following this thread for a long time but only recently registered here so i could post. Anyway here are some pics of my dual valvecaster:

http://picasaweb.google.com/lh/photo/7TEglQRTtORH-XrPrAMSbA?feat=directlink
http://picasaweb.google.com/lh/photo/8nKdyLj9lwrciY7mb7vyUw?feat=directlink

I'm running it at 18V and i've placed a jfet buffer before each valvecaster stage. I have loads and loads of questions for you guys but for now i leave only the pics 

[Renegadrian]

Hi there - I think I've seen it before - did you post it on other forums?

[intricatecode]

Only at forumusica.com it's a portuguese forum for musicians someone else did a valvecaster there too but nowhere else that i can recall.

I have to buy some more 12au7's so i can experiment with this circuit some more, there are loads of things that i'd like to try, using jfets as a ccs instead of the plate resistor, using voltage pumps so i can get more voltage using a standard 9v power supply, etc... I have loads of questions for all you guys but i have to gather my stuff before i go berserk here 

I will post some ideas i have in the next few days.

[frequencycentral]

Only at forumusica.com it's a portuguese forum for musicians someone else did a valvecaster there too but nowhere else that i can recall.

I have to buy some more 12au7's so i can experiment with this circuit some more, there are loads of things that i'd like to try, using jfets as a ccs instead of the plate resistor, using voltage pumps so i can get more voltage using a standard 9v power supply, etc... I have loads of questions for all you guys but i have to gather my stuff before i go berserk here 

I will post some ideas i have in the next few days.

Well I've used a PNP BJT as a CCS with a similar circuit, the effect is a little brighter and with some more gain:

http://www.diystompboxes.com/smfforum/index.php?topic=71864.0

Here I am using a MAX1044 voltage pump for higher voltage, but its an amp not a pedal - I'm still developing this idea. I will try it with a pedal eventually too:

http://www.diystompboxes.com/smfforum/index.php?topic=73317.0

[kurtlives]

The 12AU7 really opens up once you get past 20V DC. At 12V DC I find the sound is way to dark/bassy and compressed.

My latest 12AU7 tube project uses a B+ of 38V DC. Still want to try out something in the 60V DC - 100V DC range to see what it sounds like.

[castillogm]

Hello y'all!

I'm gonna spend my very first post on this thread since I've read all the 40+ pages of this amazing project.  It's very inspiring to see how a simple tube and a few resistors and caps can make that chunky distortion that I've been looking for a long time. 

I think I'm on that guitarist 'phase' where you're looking for pure tone and eventually get rid of those multieffects that only give you headaches while trying to adjust a ton of parameters... Now I'm trying to keep things simple, and fortunately for my quest a pair of 12at7 tubes came into my hands while I was buying some stuff from stewmac.com ("tubes? why do you need a tube? I dunno... for 10 bucks maybe will look cool in some steampunk stuff").

So now I'm waiting for those tubes and very anxious to start the project.  I'd really like to thank you all for sharing your knowledge and I hope that in the next few weeks you'll see my creation.

Regards,

Mario (mexico)

[intricatecode]

Only at forumusica.com it's a portuguese forum for musicians someone else did a valvecaster there too but nowhere else that i can recall.

I have to buy some more 12au7's so i can experiment with this circuit some more, there are loads of things that i'd like to try, using jfets as a ccs instead of the plate resistor, using voltage pumps so i can get more voltage using a standard 9v power supply, etc... I have loads of questions for all you guys but i have to gather my stuff before i go berserk here 

I will post some ideas i have in the next few days.

Well I've used a PNP BJT as a CCS with a similar circuit, the effect is a little brighter and with some more gain:

http://www.diystompboxes.com/smfforum/index.php?topic=71864.0

Here I am using a MAX1044 voltage pump for higher voltage, but its an amp not a pedal - I'm still developing this idea. I will try it with a pedal eventually too:

http://www.diystompboxes.com/smfforum/index.php?topic=73317.0

I've been following your work for quite sometime but i only have a bunch of j201 around so i went looking about on the web if it was possible to use a jfet as a constant current source and aparently it is possible but i haven't tested it yet because in the meanwhile i have been using my double valvecaster full time on my pedalboard  recording an album and playing it live.

Anyway here are a couple of links i found about CCS and tubes:

http://headwize.com/projects/cavalli2_prj.php  has an explanation on using jfets, mosfets, and other types of ccs with tubes
http://www.headphoneamp.co.kr/bbs/zboard.php?id=diy_sijosae&no=211 comparison of performance of different kinds of ccs

I haven't come around to really explore the math and concept behind the usage of ccs's with the tubes but what appealed to me about using jfets is that you can do it with a lot less parts than with a bjt even though the performance may be less. From what i've read just tying the gate and source of a jfet will give you a ccs with the value of the jfets Ids. What this value should be to use with the valvecaster i haven't had the time to work out so far.

Regarding the voltage pumps i read somewhere that the icl7660 is more robust than the  MAX1044 and is pin compatible and that the icl7660scpa version is less prone to give an audible "wine" when using it as a voltage pump.

I'm relatively new to electronics and diy effects pedals the double valvecaster was my first build so i still have a lot to learn about triodes fortunately this forum has been a great help so far and pages like this one http://www.aikenamps.com/CommonCathode.htm have  helped a lot about understanding how all of it works.

Right now i have to find the time to work out all the math in my head and review all my electronics concepts (it's been a few years since high school) so i can hopefully contribute with some ideas to 

[frequencycentral]

Regarding the voltage pumps i read somewhere that the icl7660 is more robust than the  MAX1044 and is pin compatible and that the icl7660scpa version is less prone to give an audible "wine" when using it as a voltage pump.

It's the other way aound - the 1044 has a frequency boost feature which the 7660 lacks. I have both in my stocks, and a MAX on the bradboard at the moment - I'll pull it and replace it with a 7660 and see if the whine is bad.

Thanks for the links!

[intricatecode]

Well I was feeling kind of bummed today and so i thought about getting out my trusted soldering iron and try out some of the ideas i had about using a J201 as a CCS on the valvecaster to clear my head.

Here's what i came up with:



I used it on the last triode stage of the valvecaster running it at 18v and it made quite an audible diference.

The first thing i did was to use the J201 with the source and gate tied but it didn't work so well, so i thought about soldering a 20k pot between source and gate and wiggle it about to see if it made any difference. I found a sweet spot and  using a switch compared the sound between the CCS and the standard 100k resistor and the CCS was quite a bit louder 

So then i measured the voltage difference on pin 6 between using the CCS and the 100k resistor, with the CCS i got about 15v and with the 100k resistor it was about 10v. I measured the resistance value of the pot and it was about 65 ohms, it stayed quite a bit louder up until 1k and after that started to get progressively quieter. When i went under the 65 ohms it started  to sound weird and also quieter.

So there you have it folks  now i'm happy as a camper with a louder valvecaster prototype on my hands and a couple of more ideas up my sleeve.

Please try it and tell me if this works for you too.

[Renegadrian]

Only 5 posts and you come up revolutioning the Valvy... Seems a good mod to do...After all, just a j201 and a res....

[Renegadrian]

Gonna try out this one, I guess it won't be a distortion unit but a good clean preamp

[kurtlives]

Where did you get this idea from?

I really doubt an EF86 pentode will run on 12V DC.

[Renegadrian]

I just did the vero, I found the schem googling around (don't remember where)
I uploaded in my directory, just click --->HERE