Roland Cube DI

Chabenda

Has anyone got an idea of how I can sort out a DI from my Cube so that the speaker output doesn't cut out? I'd like to be able to hook up my two Cubes without using a battery/transformer powered pedal/box.

?

babbalute

If you want to install it yourself suggest you Google for the schematic of your amp. Seems they are freely available. Shouldn't be to difficult to find the "tapping-off" point

morph

I am assuming you want to connect to the "Recording out/Headphone jack" without cutting the speaker out

That Jack looks something like this one

http://www.aliexpress.com/item-img/2pcs-mono-jack-2pcs-stereo-jack-6-35MM-headphone-jack-microphone-1-4-panel-Amplifiers-1/1498708601.html

Your signal comes from the preamp with a left, right and common earth. When there is no headphone jack the signal follows from pin 1 to 4, 3 to 6 and 2 to 5, which is then sent to the power amp and speakers

When you plug a Jack in it disconnects the power amp and speaker by pushing the contacts apart, disconnecting 1 to 4, 3 to 6 and 2 to 5. In the first pic you can see the 3 points that disconnect across the top of the socket.

All you need to do is either permanently connect 1 to 4, 3 to 6 and 2 to 5 or put a 3-way switch in if you still want the headphone capability

If it is not stereo then there are only 4 contacts to worry about, the last two pics show the mono socket

Chabenda

Thank you very much indeed Greg! Exactly what I was hoping for! I should have specified using the headphone/DI output jack.

Will tapping off from the pre-amp in any (really audible) way affect the sound generated by the units power amp?

morph

I can't say for sure but I doubt it will be significant especially if you are connecting the earphone line to a high impedance, this will draw less current away from the power amp section. However the higher the impedance the lower the volume heard through that line. Are you planning on recording your live stuff or do you want to drive it through a PA and keep the speaker working for monitoring?

All I can say is try it and see :-\

Chabenda

I have it in pieces at this moment in time. The intention is to plug it into the input of my other Cube 40. Something that I only imagine doing when playing outdoors and needing more headroom for rhythm.

Chabenda

Ummmm...ok, here is the circuit board that the jack plugs are mounted onto. There appear to be 5 pins on this, not four or six. Any advice? I'd rather ask first before hearing that pffftt.... and smelling Electrician's Aftershave...

morph

It is probably one of these

I also have a Cube and I am going to open it and see if I can test the pin outs

Attila

Here you go Chabs:

If you want to take the mute of permanently then strap the two pins otherwise place a switch there

Chabenda

Senhor Attila - I suggest that you use at least SPF50, as the sun does surely shine from your posterior!!!

?

Attila

crazy roman .... ?

morph

Bingo

Thanks Attilla

Now I can put my Cube back together again hehe

BTW I measured and the left two are connected and disconnected when a plug is pressed in as is the right two that you have shown here

I found a video of the Street cube and it shows the other two being bridged so I guess depending on model the wiring might be slightly different.

here is the wiring diagram of the Cube 40

http://www.freeinfosociety.com/electronics/schemview.php?id=1326

Chabenda

Thanks Greg! ?

morph

Pleasure, it's fun to work these things out

Chabenda

Ok, I have bridged it as per the photo and it works BUT, the signal into the second amp is way too powerful.

Any ideas Camaradas?

Edit- a variable resistor on the centre pin circuit?

Attila

oh hell there's a lot going on here as there is also impedance matching for your headphones @ 25ohm I suspect.

Problem is that your guitar has a hi-impedance output between 250k-1m config dependent @ +- 50mv which is suitable for the amps input and now you're inserting an 25ohm @ +- .5 - 2v ieeesh wenna will cook something eventually

Not Ideal but if you simply want to drop the line out level passively.

1) hook up crude passive variable L-pad attenuator (hi-wattage POT) to help find the ideal level.

Something like this - can place a high pass cap in there to prevent hi-freq loss at low vol

g

2) play with R*65,*66 and/or R67,64, on Gregs schematic (* = mono output) to drop the level.

I will give some thought and come back with pearls of wisdom (i hope) ... Greg please help !!!

morph

https://www.dropbox.com/s/uznio2do0jg7e6d/volume%20control%20circuit.jpg?dl=0

I have shown a 250K Variable plus a 100K fixed resistor across the output of the cube. This is a nice high impedence circuit that shouldn't impact the volume of the cube speaker much. The fixed resistor is just to protect the input of the other amp should the volume be turned all the way down. This will short the input of the amp out, not good

I am assuming you are only talking mono? If you are talking stereo then you buy a dual package and do this for both channels

morph

If you have a guitar foot volume pedal try this first between the cube and the amp. This is essentially the circuit I have given you

I have tested this on my cube output and it works perfectly except that it requires a small variation to dampen the volume down.

You could reduce the values of the resistors down but this circuit will protect the input of your amp, and do no harm to the cube

Chabenda

Ok, I have stolen a 200k pot out of my fizzled JTM30. Now for the resistor. I like playing about and although Cubes aren't that expensive, I'd prefer not to fizzle this one. I know squat about resistors and have been looking for means to ID them. Please before I redo "The Great Escape" in smokey blue, can you confirm that I am looking for 1 Brown and 2 Black lines on the resistor (the one I have has a gold line on the other end).

Attila

100k
brown =!
Black =0
yellow = 4 (multiplier)