#1
Hi,
I recently came by a second-hand Roland Blues Cube BC-60 1X12 amp, that comes without a headphone jack..
How difficult would it be to wire in a jack for headphones? I live in a quiet enough neighbourhood, and the next door neighbour is pretty cranky, so much so that I know for sure I'd be killed if I played through the speaker..
I'm handy enough with a soldering iron, if someone would be able to pretty much tell me how exactly to do it?

Thanks
#2
The headphone jack really isn't necessary, you can turn down amps as much as possible. This is coming from a guy who shares a room with a 100 watt 2x12 amp. Just start the volume on zero and slowly increase it until it is satisfactory, You honestly have to be playing VERY loudly for neightbors to hear you, sound barely escapes my room when I'm playing at a comfortably low practice volume and I've got a loud setup.

Low volume won't sound the best, but It will probably sound better than a headphone out.
Quote by R45VT
Bastards.
Last edited by Viban at Nov 14, 2013,
#3
I'd go with Viban on that, and maybe check out when the guy is gone - like to work or other regular outings, keep it really low and in reasonable hours, and when is is out to work for the day etc., then turn it up a little bit then.

It's not so much the guitar playing - it's the complete lack of respect that pisses people off.

I have a naighbour who is an arsehole and a drunk - likes to open his front and back door wide open and then turn his stereo right up at 2 or 3am on a week night and this wakes us up and ALL the neighbours.....

He gets his kicks out of getting his idiot teen age friends doing burn outs and donuts, across the neighbours laws like every 6 weeks the ****** will try it on...

After a couple of years of this, all the neighbours want to kill him......

The guy might actually LIKE really nice guitar work.... provided that it's within reasonable hours and he can sit down and HEAR the TV while he is watching it..

Go ask the guy, talk to him... tell him what you want to do and why and ask him how can you do it without pissing him off.

If your considerate of other people and "their needs" - some times you can get along quite well with them...

Also sometimes the walls can be paper thin.....


I'd do the head phone jack addition, either ONE of two ways.

You need to find out the headphone voltage output. That is the first thing.

Get a multimeter and a stereo and test it with the power switch to the headphone jack, on. Look up headphones and jacks - they have switches in them that route the signal into the headphones, instead of the main amp and the better ones switch the main amp off via relay.

Get a hold of the circuit diagram from the manufacturer, or trace the signal across the circuit boards.

Assuming it's IC amplfication.....

There is a control and preamp stage, and then there is the main amplifier stage....

You need to check the voltage AFTER the preamp stage - this is where your tapping point is.

You MIGHT have to cut one of the copper tracks to get the live power level and not the coupled to the amplifier stage power level.

The circuit board should be marked with the + and - of the tracks...

There may also be TWO circuit boards - one for the controls and preamp, and another for the main amplifier.

If the circuit voltages are similar too the voltage for the head phone jack on the stereo (there are tables on the internet with all of this too)

http://en.wikipedia.org/wiki/Line_level

http://en.wikipedia.org/wiki/Headphones

Yeah to you need to tap into the tracks between the pre and main amp and switch out the main amp - most jacks have this switch in them - and get the polarity right in the connections.

Should be pretty easy.

It tends to only go one of two ways... either it works well or it's a bit too weak at full volume or it's very easy to drive the head phones into distortion...


The other issue is that you can buy a cheap basic amplifier or something that has one, with a proper LARGE 1/4" (6mm) head phone jack in it, like an old stereo or a practice amp etc...

You need the 1/4 inch ones, as the 3.5mm ones are too frail and easy to break.

http://www.schematicsunlimited.com/r/roland

http://www.ebay.com.au/itm/ROLAND-BC-30-BC-60-BLUES-CUBE-SERVICE-NOTES-ENGLISH-BOUND-CIRCUIT-DIAGRAMS-PCBS-/300632162156?pt=Vintage_Electronics_R2&hash=item45ff12bf6c

Look around - I don't have much experience with tube amps... but IC's are fairly straightforward.

While the electronics are generally safe to work on when live, just be a bit careful around the high voltage stuff from the mains and around the transformer / power supply.
#4
Here's the service manual/schematic (may not work correctly if you try to download it with your phone):
http://www.schematicsunlimited.com/r/roland/roland-blues-cube-bc30-bc60-amplifier-service-manual

The best place to put a headphone jack would be on the end of C30 that is not connected to the wiper of the master volume pot. Wire the jack to break this connection so that the power amp (which is just a single chip) will switch off. If the signal is too loud in the headphones, you can try putting a resistor in series with the signal. From what I've seen, the general rule-of-thumb value is 220 ohms per watt of output power into the phones. Remember to use the correct resistor wattage.

If you need a diagram for wiring the jack, I can make you one.
#5
Thanks for the replies, it seems harder than I thought, but I reckon it's not impossible for me!
I have a stereo Jack left over from a build that GFS accidentally shipped out, so I could probably use that, right? Plus I have 3 different practise amps that I could potentially canabalise!


Jim, a diagram would be great if you wouldn't mind! Would it be possible to include a pot for volume control with that, or would the master do that for me?
#8
That jack won't be able to switch off the power amp. So when you plug in the headphones, you'll still have the main amp blaring.

You want one of these (this one will match the amp):
http://www.smallbearelec.com/servlet/Detail?no=798

You'll need to solder both signal lugs together so you'll be able to hear the mono signal in both speakers of the headphones, but if you insert a mono plug into this jack, it will ground out both lugs and you won't hear anything.
Last edited by Invader Jim at Nov 18, 2013,
#10
No, you just need the jack (and know where to solder it). In the schematic I linked to earlier, there is a capacitor on the wiper of the master volume pot. It is designated as C30. Note that the actual PCB may not designate this cap as C30. You'll have to look at where the trace from the middle lug of the master volume goes.

What you want to do is cut the PCB trace on the end of this cap that is NOT connected to the wiper of the pot. You'll solder one wire to the end of the cap on one side of the cut and another wire to a previously connected point on the other side of the cut. You'll also need to solder another wire to a ground point in the amp. Then you'll be ready to wire the jack (I can make a diagram for that part).
Last edited by Invader Jim at Nov 18, 2013,