Interesting Mod: a Boss SD-1 with a 12AX7 in it.

[bobbletrox]

Pics:
http://www.diokay.com/images/prod/Tubesd.jpg
http://www.diokay.com/images/prod/Tubesd2.jpg

I found this on the HC effect forum.  Real or fake?  I mean, it's not like you can just wack a tube in like you can a new opamp.  Certainly food for thought though.

[Thomas P.]

reminds me a little of this:
http://www.geofex.com/FX_images/realtube.jpg :wink:

[remmelt]

if that is for real, it would be an even tighter fit than paul's tube-box we saw the other day...

[petemoore]

it looked like it was glowing.
 i think a 12ax7 is a touch too large to fit in a boss battery compartment...looked like there was one in there.
 as far as 'securely'...[   ]

[Ansil]

ok i got to try this now. and see if it works.  EDITED  ok from what i am seeing in there i dont' think you can get a socket in there looking at my boss. but i am pretty sure you could get in there and put a tube in if you used the little inline wire clamps i was talking about before as the wires to hook into your tube pins.  will post back in a couplle hours after i try this.

[RDV]

That's funny! I can imagine myself stepping on it and hearing CCRRUUUNNNNCCCCHHHH!!!!!!!!!!

RDV

[Thomas P.]

That's funny! I can imagine myself stepping on it and hearing CCRRUUUNNNNCCCCHHHH!!!!!!!!!!

RDV

D'OH!

[Paul Marossy]

If that is for real, I'm impressed! It's even got some holes drilled on the side, for ventilation I assume. What I wonder about is, how the hell do you get the tube out of there?!

[RedHouse]

Photoshop will put "glow" into a pic like that just fine.

[casey]

why are so many people eaten up with the tube thing....?

i have a tube amp that i play through, and it sounds
WAY better than any ss amp that ive ever played....so i understand
it on that level....but it seems as if people are just eaten up with
the whole tube thing....keyboards with tubes behind glass.....
korg has a drum machine with a tube, and im really seeing it
alot in the recording industry....it's kind of silly really....
behringer has a mic pre that has a nifty little 12ax7 behind a glass
with an l.e.d. behind it.....

takamine has a tube in one of their acoustic guitars....which is
ridiculous if you ask me.....i would rather have an outboard tube
pre with an acoustic....  which, come to think about it, that's what
im using....  a presonus tube pre....with an l.r. baggs pickup.  im not
using the tube pre because i wanted to impart a "warm" sound to
my tone, it's the only preamp i have, and i happened to have it
for recording.  99 bucks.....  and most of the sound is jfet.

people are crazy about tubes in their gear, and most of it is low power
noisey stuff with no headroom....(like my presonus)
but then again, that's another topic.
im all about tube pedals and such, just because it's a fun diy....but
leave the sd-1 alone...it's a great pedal....  

[casey]

the takamine tube pre in their guitar runs on 3 volts....  what's the
point of even having it in there?

http://www.takamine.com/?fa=cooltube2

sorry to get off topic there folks.... :roll:

resume...

[Paul Marossy]

Yeah, I thought that onboard preamp tube on a guitar was going a little far...

[Ansil]

i find it neat personally and with the advantage of the little ehx transformers we could make a nice little tube box in a boss pedal.. sure theres no real reason as to why to do it. but eye candy sake.. but if we are going to just make it eyecandy why not jsut get some 6112's jor a 6112 adn a 6021 and make a nice little medium/highgain amp. out of it.

i am sure that if zvex can do it in a hammond he could do it in a boss box.  come on z man make me a boogie in a boss pedal.


now as for the seriousness of this thread i went back to the shop and tried it.  actually it works fine. however you need to keep in mind these things.

1.  try to find a skinny 12ax7 [all tubes are not created equal lol]
2. if you still have that fet crap switching system your fine other wise you need to adjust your tpdt switch carefully.
3. it really works better to put it sideways but yo uhave to drill out where the spring goes. but when you do this the pedal cavity is fatter here and you dont' have to worry about crushing it.

[Claus H]

Found more pic's



Claus H

[Claus H]

The battery pocket of a boss pedal is 27mm wide, a 12AX7 is typical 22mm wide, no problem..

Thickness is the problem (That's what you meant by skinny) You need route out the bottom and the back of the battery compartment and I suppose a small socket could be placed in the there.. if you drill the hole in the front like in the picture you should be able to take out the tube easily...

Length of the compartment is 55mm and the length of a tube without it's tip is 50mm typical..

It's not an easy job but could be done.. you might use the two triodes of the tube as clipping "Diodes"

Claus H

[phillip]

Hmm any idea what the tube's doing in the circuit?  The OPAMP is still on the board...

That looks like a pretty interesting mod.

Phillip

[Claus H]

you might use the two triodes of the tube as clipping "Diodes"

Sorry to Quote myself..

Writen about here http://www.geofex.com/Article_Folders/mandt.htm see Clipper using Grid-Cathode "Diode"


Claus H

[bobbletrox]

What's the component replacing the diodes with "SD1" written on it?  If it weren't for that mystery component, my first guess would be that the tube is being used in place of the clipping diodes.  I'd imagine the Boss circuit would have to be modified to handle 12v as well.

Anyone want to take a stab at how you'd implement the tube into the SD-1 schematic as a clipping grid-cathode type dealie?

[Claus H]

12volts?? 6.3v could do it, if you run the filaments in parallel instead of series..

Claus H

[SnooP_Wiggles]

replace a couple of low voltage caps and change the current limiting resister powering the LED and sd-1 will run on 12v-16v or so.