Zoom B3n amperage requirements

[songofthewind]

Hey there hepcats 

Does anyone know how many amps the B3n actually draws? I ask because I have tried various power bricks, isolated and non isolated, in an effort to tame the digital whine it gives off if used with other pedals.

Currently I provide it with a separate wall wart, which works well, but means an extra power cable and clutter. I also have a Harley Benton Powerbank, but the Zoom whines like a mofo when powered by it. 

I am hankering after the T Rex Chameleon advertised on BC, but I am concerned that the individual outputs of 300mA will not be sufficient.

Can anyone advise? Al Krow, do you know about this?

Any words of wisdom will be much appreciated.

[Woodinblack]

Not as much as you think but the digital whine is a thing, you cannot share its supply with any other device, it has to be fully isolated.

I have it on my board, it is now quiet, but I had to move things around to get rid of the noise, that and the smoothhound - they certainly don't play well together

[songofthewind]

Yes, your experience is like mine, then.

It doesn’t seem to like being used in conjunction with ANY other digital device. Really annoying, because otherwise it’s a great unit.

[dannybuoy]

On the Truetone units, you can apparently ignore the mA labelling on individual outputs as long as your don't exceed the total for the entire brick.

The Strymon units might work well too, they also use switching technology and have really high mA ratings per socket compared to most isolated supplies based on transformers.

[Dood]

The manual suggests a 500mA power supply, but the internet doesn't seem to suggest otherwise. I know that will limit you on selecting a power bank as they often have up to 300mA outputs. Though DannyBuoy is right about certain units being able to "share" their current output.

The digital whine can be alleviated by using a power supply that has individually isolated outputs. Unfortunately as I've discovered by searching the internet, lots of manufacturers say their power supplies have isolated outputs, but the reality of the situation is often different! Getting the lid off or even better, analysing schematic diagrams can sometimes be the only way to be sure that some manufacturers aren't telling fibs!

I did find a thread somewhere on da webz with lots of "guts shots" of power supplies and diagrams that pointed out which supplies were good.  

[Woodinblack]

Mine is on an isolated output at 300ma and is fine, noisewise

[operative451]

I got one of these! https://www.amazon.co.uk/gp/product/B07CS6T95Z/ref=oh_aui_detailpage_o05_s00

which i use on the branch of a daisy chain than has the zoom on, with other pedals (see my many posts over on the pedalboard thread) and it really nicely chops out the 'eeeeeeeeeeeeeeeeee' noise.  It can take a little bit of swapping plugs as there's probably something about where the zoom is compared to other the pedals in the power sequence but it does the job for less than 10 quid..

[Al Krow]

Isolated PSU (to avoid noise) + 300mA min would be my recommendation. So the T Rex should be fine if it's ticking both these boxes. 

You can always do a parallel current draw from two outputs using an appropriate 2 into 1 connector, if it seems to be falling short on the juice being supplied to the B3N, but you should be ok with one 300mA output. 

Edited November 22, 2018 by Al Krow

[songofthewind]

Thanks, everyone for your valuable contributions. 

The Joyo device looks interesting, and might be worth a punt. I’ve never seen anything like that before

I am really not good on any aspect of elecktrickery, so bear with me. Al, your suggestion is interesting but puzzling. I thought if I used a doubler as I think you describe, then surely that also put 18 volts into the Zoom? Can you illuminate my darkness?

[Al Krow]

So there are two different doublers you can get: a current doubler (which leaves the voltage the same) and a voltage doubler which does what it says on the tin...

(The really clever stuff is the voltage divider which let's you take your 18V output and turns it into a 9V output. Given that I have two 18V outputs on my MXR ISO Brick and only 9V pedals that's been really helpful in making the most of my PSU).

 

Edited November 22, 2018 by Al Krow

[songofthewind]

A current doubler, eh? Where might I obtain such an item?

[Al Krow]

Here's one made by the same chaps who make the T Rex PSU you're after.

And actually provided both outputs are the same voltage (e.g. 9V) you can combine different current outputs e.g.  300mA +100mA => 400mA etc

 

Edited November 22, 2018 by Al Krow

[songofthewind]

I think I’ve got one of these! In a drawer. Thanks, Al, you da man.

[Al Krow]

6 minutes ago, songofthewind said:

I think I’ve got one of these! In a drawer. Thanks, Al, you da man.

Just make sure it's a current doubler not a voltage doubler (it's more likely to be a current doubler)

Too much available current is harmless, the pedal will only draw what it needs.

But too high a voltage and you could end up frying your pedal.

... gonna need to get someone more expert than me to tell you if there are any obvious tell-tale differences in appearance between the two.

Edited November 22, 2018 by Al Krow

[songofthewind]

Yup, I understand. I will do nothing until I am absolutely sure. Thanks for your help.

[Woodinblack]

Yesterday I took my B3 apart. I had a problem with it recently on gigs. Like this:

Effect 1, all buttons work. Effect 2, up / down work, page didn't. Effect 3, Up and Page worked. Also patch select and save didn't work.

So I took it apart and checked what was wrong. Didn't find anything but putting it back together I got this:

Effect 1, page up and down worked. Effect 2, nothing worked. Effect 3 Page up worked. Now none of the buttons along the top worked apart from tempo! I have a gig tomorrow.

So I took it apart again, but this time upstairs, not sitting on the sofa by the nightlight. Found that the circuit board had always had a problem where it was done up too tight and had cracked the circuit board, and eventually one of the tracks that held the buttons failed. By taking it apart I let the rest of the thing flex.

So now I soldered those lines together, put it together and everything works, apart from patch down, which is not working because the button is actually broken, but as the patch up and down are replicated by the big buttons, that isn't so much of an issue.

However, putting it back together, I remembered this thread and measured the power consumption.

At startup it takes 160mA. After it has started it goes to 140mA. Once the led saving goes on it goes to 120mA. Switching of the effects on and off has no increase of current. Plugging a DI in goes up a few mA. However, I couldn't get it to take over 160mA whatever I did. Maybe with USB it might take more, and almost certainly with headphones, I didn't try those, but they aren't normal gigging issues. I am pretty sure it would be happy on 200mA.

 

 

[Al Krow]

I'm very impressed with your DIY skills Woody! 

Just to point out the obvious on the power front, that you have the older B3, rather than the more modern and, dare I say, more power hungry B3N with it's newer more powerful chipset. 

[songofthewind]

Good work fixing the B3.

I had a similar issue with an old G21.U. When I took it apart, the little buttons were all on the same plastic moulding, and it had snapped in a couple of places. A dab of superglue to weld the breaks, and all was well.

The buttons on my G3 (same chassis as B3) are still good. Looking inside my Zoom units reveals pretty good build quality for the money, I think.

Btw, what device do you use to measure the power consumption?

[Woodinblack]

2 hours ago, Al Krow said:

I'm very impressed with your DIY skills Woody! 

Not really that DIY, I used to be an electronic engineer back in the day before I left for the easier world of software

2 hours ago, Al Krow said:

Just to point out the obvious on the power front, that you have the older B3

That is true

59 minutes ago, songofthewind said:

The buttons on my G3 (same chassis as B3) are still good. Looking inside my Zoom units reveals pretty good build quality for the money, I think.

Btw, what device do you use to measure the power consumption?

I am impressed with the build quality, apart from that bit, yes. Bad screw placement really. 

I just measured it with a meter