slajeune: is this the Ruby Tuby, sans op-amp?

[cx_deluxe]

Can't tell if this is the verified non-op amp version or an early experimental version.

I got it from here:

http://www.elixant.com/~stompbox/smfforum/index.php?topic=19348.0


I want to build a low gain version without an op-amp so I can drive it with one of my boosters.  I'm pretty new to this stuff.  This will be my first tube build.

PS: in one of your threads I read that you "liked the first version best" and elsewhere that you "wanted to remove the op-amp"
Is this the one or am I confused?

cheers!,

[The Tone God]

Can't tell if this is the verified non-op amp version or an early experimental version.

I got it from here:

http://www.elixant.com/~stompbox/smfforum/index.php?topic=19348.0

Slajenue's Ruby Tuby Amp is a tube preamp with a opamp boaster in front and a 386 power amp on the end. It can be found here

http://www.sopht.ca/index.php?s=28

I want to build a low gain version without an op-amp so I can drive it with one of my boosters.  I'm pretty new to this stuff.  This will be my first tube build.

PS: in one of your threads I read that you "liked the first version best" and elsewhere that you "wanted to remove the op-amp"
Is this the one or am I confused?

Later someone, I belive it was Bobbletrox, was more interested in the tube preamp portion then the 386 part so they extracted and redrew the tube preamp that I offered for the Ruby Tuby which is the schematic that floats around occasionally. It can be found in one of these threads:

http://www.elixant.com/~stompbox/smfforum/index.php?topic=20008.0

http://www.elixant.com/~stompbox/smfforum/index.php?topic=36320.0

http://www.elixant.com/~stompbox/smfforum/index.php?topic=38173.0

Andrew

[cx_deluxe]

Ok.  Gotcha.  Thanks for the reply.

I want to build the Ruby Tuby amplifier (12ax7 into lm386) without the opamp boost.   
That way I can drive the tube with one of the boosters I already have (and like) -- rangemaster, mosfetbooster, sparkle boost -- something like that.

Does this make sense or am I nuts?

If I'm not crazy I should be able to just leave out the op amp and all of its related bits, right?

[The Tone God]

Nah. I might be nuts coming up with the design but thats another matter.

The earlier version of the Ruby Tuby had just the tube section, which is the schematic that you see floating around, connected to the 386 in the same manner as the Ruby Tuby on the Slajenue's site. It was designed that way so people could use what ever boaster they wanted much in the same manner you are suggesting so go for it. The opamp boaster was added later to be a more complete "in-one" system.

Have fun.

Andrew

[slajeune]

Hi,

wow, I have been away for a while!  I haven't really played with pedals in quite some time.  The version on the Sopht site (the ruby tuby) is the only schematic that I have of the ruby tuby.

If you want to have a design without opamps, see the 12v section : http://www.sopht.ca/index.php?s=26

The preamp tube used is a 12u7.  Althought, some have subbed it with a 12AU7 and it seemed to behave the same way.  If you want to push the amp with a booster pedal and have the tube section provide the distortion, I suggest the following.

- Start with this schematic (you can sub the 12U7 by a 12AU7):
http://www.sopht.ca/schematics/sopht_12k5-v6.jpg

- Remove the second bypass cap (cap C4).  This will ensure that it is a 'clean' preamp.

- Replace R7 by an audio 1M pot

- Place the LM386 after the audio pot as per the Ruby Tuby

That way, you get an all tube preamp that you can drive which ever way you want.

I haven't tested this design, but this might be of some interest to people wanting a different twist on a MXR+ distortion / tube screamerish:

http://www.sopht.ca/schematics/tube-tube_screamer.jpg

Cheers,
Stephane.

[cx_deluxe]

Thanks Guys.

TG:

"The earlier version of the Ruby Tuby had just the tube section, which is the schematic that you see floating around, connected to the 386 in the same manner as the Ruby Tuby on the Slajenue's site. It was designed that way so people could use what ever boaster they wanted much in the same manner you are suggesting so go for it."

That's exactly what I'm gonna do.  I have all the necessary parts, so I'm starting here.  I'll post in this thread again with a report.

Slajeune:

Good to see you're back.  I'm interested in sopht.ca (canadian, eh? me too).  I don't have all the parts for the 12v project so I'm starting with what I've got.  Your manifesto introducing the Ruby Tuby describes my thinking exactly.  Thanks for that!

cheers!

[brad]

I haven't tested this design, but this might be of some interest to people wanting a different twist on a MXR+ distortion / tube screamerish:

http://www.sopht.ca/schematics/tube-tube_screamer.jpg

Cheers,
Stephane.

AAAAHHHRRGGG!!  You magnificent bastard!!  I've been trying to learn tube theory so I could build something simple like this

Do you mind if I ask some quick questions?
a) What kind of wall wart do you recommend?  Is any extra filtering needed?
b) No input cap necessary?

This would make a great tagstrip pedal 

[slajeune]

Hi Brad,

a) the wallwart should be at least 12VDC .3Amp (the filament for the 12AJ6 is .15A).  Yes, I do suggest some filtering as it is going to induce hum.  You could try a simple electrolityc cap accross the positive and negative of the v+.  You could also buy a regulated & filtered wallwart, even simpler.

b) No input cap necessary (as this is a tube circuit and tube amps typically don't have input caps).

Please note that the circuit hasn't been tested, although it should work.

Cheers,
Stephane.

[cx_deluxe]

Today it's a radio.

It goes "bzzraaaap", then it's warmed up, and I get a faint radio signal.  No guitar signal throughput yet, but I haven't had time to troubleshoot it.  The volume pot appears to work.  The tube glows orange a little.  Is that normal?

[slajeune]

Hi CX,

Today it's a radio.

It goes "bzzraaaap", then it's warmed up, and I get a faint radio signal.  No guitar signal throughput yet, but I haven't had time to troubleshoot it.  The volume pot appears to work.  The tube glows orange a little.  Is that normal?

Interesting, so, you built a 1 tube radio 

Ok, for starters, it is ok for the tube to glow orange, that is the heater.  It needs to 'warm up' the tube for it to operate.  As for trouble shooting, please take voltage measures for all pins of the tube to ground (so, black probe connected to ground and use the red probe to check each pin one by one).  Please report all voltages.  Second, check the input jack.  99% of the time, we make a mistake wiring the jack.

Cheers,
Stephane.

[brad]

Thanks for the info Slajeune.  I'll have to brace myself for some crazy international postage costs and order a few 12AJ6 tubes and sockets

[cx_deluxe]

I have signal throughput.  Less volume than I anticipated, even with boost in front.  May be building the opamp version afterall?

Here's the voltages


Lm386
pin 1- 1.40
2- .01
3- 0
4- 0
5- 6.95
6- 14.55
7- 7.25
8- 1.62


12ax7

1-   10.80
2-   -.33
3-   .03
4-   12.11
5-   .01
6-   11.37
7-   -.50
8-   .01
9-   not connected but measures 6v


GL7812 voltage regulator

in-17.55

out-15.52!

testing took ~5min.
and by the time I was done heater pin read basically 15v too.  I shut it down.
The vltage reg must be failing?

[slajeune]

Hi cx,

Yes, please check the voltage regulator as it is unusual for it to fail.  Also make sure that it can sustain the amperage (you need > .5A for the regulator).

Ok, can you please try this (I don't have the build anymore).  Replace both 100 ohm cathode resistors with a 22k (yes, you read right, 22k) cathode resistor?  When I designed the ruby tuby, I didn't have any circuit modeling.  With the model that I am using, this seems to be the most appropriate cathode resistor at 12v with a 220k plate resistor.

Let me know if this helps volume wise!

Cheers,
Stephane.