More info on MIDI In phantom power please!

Me

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Can anyone tell me what voltages comes out the MIDI in port on what pins of the Herbert? I'm considering modding something to phantom power it.

I'm interested in use with a 5-pin cable, so pins 1 & 7 won't be connected. So it implies from the manual that pin 3 is + and 6 is - (or with a 5 pin cable the 2nd and 5th pin), but only says it's 9-12V AC or DC. From what I can tell it does 12 VDC on pins 1 & 5 of my cable, so hence pin 2 and 6, not 3 & 6 as stated in the manual. :confused: Probably a mis-print then, but I want to make sure I'm not missing something as I really don't want to screw anything up.

The thing I want to power wants 9V AC tbh, so I'm yet to find if it'll all play nice via 12V DC and a bridge rectifier but figure there's no point taking the other end to bits and analysing it til I know what supply I definitely have. What comes out 1 & 7? I'm guessing 12V DC too? I don't have any 7-pin cables and am loathe to stuff a multimeter in my MIDI in port in case I splay the pins out.

Don't worry, I'll be drawing quite a bit under the max 800 mA current limit mentioned in the manual! :D
 
12V DC

numbering Midi goes this way . . .

midi.jpg
 
Cheers! The manual makes more sense with that diagram and the odd numbering! So that's numbered looking at the plug end then (rather than socket)?
 
Looking onto the jack on the amp's back, amp flipped, pots to you:
PIN 3 = 9 o'clock
PIN 1 = 3 o'clock
PIN 5 = 10.30 o'clock
PIN 4 = 1.30 o'clock
well and my guess is that PIN 2 is self explanatory :D

:)
 
Cool. So, since looking from the front of the amp that's the same as looking into the cable end.

I've done a mod to my pedal at lunch time. Gotta go for a hair cut, then will get home with enough time to double check it again against this, then blow my amp up. :LOL: :LOL:
 
Works fine from an operational point of view, but hums like a bastard. I think either some caps may be in order else the whole plan is scuppered. :(
 
This! See attached.

Other notes:
* With the guitar through the pedal switcher it seems to hum, into the front of the amp it doesn't.
* The midi lead to the Diezel is tie-wrapped to a mains lead which normally powers the pedals, but this wasn't connected to anything at the time so it can't be hum via the pedal PSU.
* It doesn't hum lots (tiny tiny amount, but barely audible) when powered by the 9v ac PSU, although obviously I can't plug this in with the mod or I'll put AC onto the Herbert's DC phantom power pins.
* Running just the ground control from the Herbert without the pedal switcher does make the herbert hum ever so slightly, but barely noticeable.
* Running in the config in the diagram without the Ground Control (just the Pedal Switcher) makes all the hum appear, and it's tone is just changed ever so slightly by adding the Ground Control back again onto the end of the chain.

Thanks a lot for your help Olaf. You're a star. ;)
 

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I need to have a look at the manuals before answering in detail here . . . will reply later today after reading . . .
 
Your pedal needs 9 Volt AC to get more than 12 volt
DC for the internal voltage 9 volt regulator. At least
you need 3 volt more on the input versus the
output.

The 12 volt DC from the Diezel will be about
11.4 volt DC after flowing through the bridge
rectifier. This is not enough for the voltage
regulator inside the pedal and will cause hum.

This is one possibility.

Best,
Peter
 
The double rectification (just discussed that with Peter on the phone) will cause the trouble here.
See Peter's post. btw: he's the star, not me.

The easiest mod would be to add a 2.5mm jack to Herbert's back, uninstall the phantom power wires from Herbert's midi jack and run 9V AC thru the midi cable instead. Then it would make sense - but you need to drill a hole and mod your Herbert and still need to use a WallWart thing somewhere.
Herbert's internal supply would be 20V AC (for phantom, midi and such), but thats obviously too much for the Voodoo stuff . . .
 
You could also bypass the second rectification (inside the pedal thing) and try that - if the regulator is a 12V type. It could also be possible that those 9V AC are voltage doubled and then recitified/regulated to result 15V DC - the higher the better for certain buffers. But my guess is 12V . ..

But please measure the ampêre suckage from both units. (seems you know it already . . .)
 
Thanks Peter and Olaf. I love you guys, you're the best! :D

Hmmm... to mod the Herbie or not... Would be a far more elegant solution, but then I can never have a head/cab/ground control only jam session when I'm feeling too lazy to take everything. :confused:

I assume the phantom power inside the Herbert comes off the mains transformer, gets rectified and then goes through a 12V regulator? I assume there's not going to be enough voltage to put a 13V regulator inside the Herbie instead? Else I can't pop a few components out or bridge them and get a higher AC out down the phantom power?

I might have a look again as the Pedal switcher path should be totally pure and I thought isolated, just relay switched. So I guess it's either magnetic emissions from the underpowered regulator going round inside the pedal switcher and being picked up, else maybe it's noise on the supply to the buffer op amp front of it (which I'm not using due to my fuzz pedal) that's making the buzz into the audio path.

Think I'll have to open it up and follow some more tracks around inside the pedal switcher. I'll look at the output of the pedal switcher's buffer with an oscilloscope and see if it looks noisy too.

Gonna have a busy evening I think... :doh:
 
duesentrieb":1cz2q4xt said:
You could also bypass the second rectification (inside the pedal thing) and try that - if the regulator is a 12V type. It could also be possible that those 9V AC are voltage doubled and then recitified/regulated to result 15V DC - the higher the better for certain buffers. But my guess is 12V . ..

But please measure the ampêre suckage from both units. (seems you know it already . . .)

Good plan!

I don't know the current individually but the supplied 9v ac PSU with the pedal switcher is 500 mA output and is designed to phantom power the Ground Control from it. So whatever it is it should be less than 500 mA by whatever margin voodoo labs intend.
 
Just skip the pedal thing and the pedals - use Guitar --> Herbie --> Cab with a midi switcher :D

And keep in mind that with Herbie's switchable loop you can switch in/out at least one pedal (Delay, Reverb, Chorus).

Just see your current calculation - cool then. And Herbie's 20VAC xformer supply of course is fuse protected.
 
duesentrieb":1ohgn26z said:
It could also be possible that those 9V AC are voltage doubled

I can't guarantee in the ground control, but that works fine on its own. The rectifier in the Pedal Switcher is where I put in the diagram so there's not mini transformer or visible magic that comes before it's converted to full-wave rectified dc.

I wondered if the Varistor could do something but it hums without the Ground Control connected, so it should just be open circuit in that config.
 
To double a voltage all you need are two diodes and two caps . . .

06041611.gif


Just measure the out of the voodoo pedal volts regulator. Should be 12V . . . then you're fine.
 
duesentrieb":lfkool2u said:
Just skip the pedal thing and the pedals - use Guitar --> Herbie --> Cab with a midi switcher :D

And keep in mind that with Herbie's switchable loop you can switch in/out at least one pedal (Delay, Reverb, Chorus).

The Herbert does the most beautiful Clean, Crunch and Distortion, but it doesn't do the filthy nasty fuzz! Peter designed it to sound beautiful, but sometimes I want nasty! :LOL: :LOL: Can't put that in the switchable as post wrong levels so goes super-saturated and then too low output. One of my fuzzes doesn't like anything other than passive pickup input either. :doh:

duesentrieb":lfkool2u said:
Just see your current calculation - cool then. And Herbie's 20VAC xformer supply of course is fuse protected.

20V you say? RMS? Does that have a regulator then? I'm guessing what come out the rectifier/smoothing cap is bigger than 12V then? If so, and it's a voltage issue I can swap the phantom power regulator in the herbie for a bigger one?
 
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