Members mpoirier Posted June 5, 2011 Members Share Posted June 5, 2011 Hi, Is there a place where I can see generic schematics about adding phantom power to stomp box ? I know all stomp boxes are different but all I need to know is how phantom power integrates to replace the internal battey or external power supply... Thanks, Michel Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted June 5, 2011 Members Share Posted June 5, 2011 Could you explain more about what you want to do? That doesn't really make sense. Link to comment Share on other sites More sharing options...
Members Pope on a Rope Posted June 5, 2011 Members Share Posted June 5, 2011 Could you explain more about what you want to do? That doesn't really make sense. OP wants to do away with batteries and adapters and instead use phantom power to supply the pedal. I understand what you are wanting to do but I don't have an answer for you. Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted June 5, 2011 Members Share Posted June 5, 2011 OP wants to do away with batteries and adapters and instead use phantom power to supply the pedal. I understand what you are wanting to do but I don't have an answer for you. But I guess I don't get the point. Phantom power is just a power supply that you'd have to run to each pedal anyway. I don't see the difference btw having that and a power supply designed to power pedals. It just seems like a difficult way to solve a problem that's been solved over and over again by many cheap and easy off the shelf solutions. Link to comment Share on other sites More sharing options...
Members Pope on a Rope Posted June 5, 2011 Members Share Posted June 5, 2011 But I guess I don't get the point. Phantom power is just a power supply that you'd have to run to each pedal anyway. I don't see the difference btw having that and a power supply designed to power pedals. It just seems like a difficult way to solve a problem that's been solved over and over again by many cheap and easy off the shelf solutions. This is the do it yourself forum. That's the point I always assume. I have a few pedals I wish could run off phantom power. I'd rather not have to worry about external power in some applications with certain pedals. Especially when it comes to bass pedals. I use them infrequently and mostly in front of a mixer which supplies phantom power. The pedal's power adapters tend to disappear and I never have spare batteries when I need them. Link to comment Share on other sites More sharing options...
Members mpoirier Posted June 6, 2011 Author Members Share Posted June 6, 2011 But I guess I don't get the point. Phantom power is just a power supply that you'd have to run to each pedal anyway. I don't see the difference btw having that and a power supply designed to power pedals. It just seems like a difficult way to solve a problem that's been solved over and over again by many cheap and easy off the shelf solutions. Ok then, if you must know everything... I use a few Tech-21 pedals to record direct through my Presonus Firebox Mic input which provides phantom power. My Acoustic DI and Bass DI already get phantom power from the Presonus, I want my Classic and eventually other SansAmp Character Series pedal to do the same. It's just easier for me this way... I'll keep looking and post results here if I see something intersting, I am sure others would be interested too. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted June 6, 2011 Members Share Posted June 6, 2011 Mr brown is well aware of what forum this is. He posts here regularly. He was asking the question to clarify as do I because of the wording of the question. Phantom power is usually associated with low impediance condencer microphones, not guitar pedals. If someone wants to install a 9v power jack to a pedal so it can run off a 9vdc adaptor, thats a piece of cake. Running a guitar pedal off of 48v phantom power designed for a mic may not even be possible and dangerous to the unit that provides it. It would definately require installing TRS jacks and stepping the voltage way down. If the OP is calling a 9vdc wall wart or other simular power adaptor Phantom Power, it comfuses others because its not a term used with guitar pedals only Microphones. Technically its correct, but Its never been used with guitar pedals in the 45 years I been an electronic tech. If the pedal was designed for battery use only, its important you use a power supply that has no AC leakage so theres no hum. I suggest using a Dan Electro Zero hum adaptor or a Boss adaptor. Either will work on a pedal that has no additional filtering added so it will be hum free. Other adaptors may cause a bad hum. For the jack. You can install the standard DC jack or you can use a battery snap adaptor. The DC jack has a switch in it that is wired to the battery like the input jack is and kills the power coming from the battery. Its hard to tell what michael was wanting to do from his original post so he needs to clarify what he's wanting to do, what kind of pedal, what kind of power etc. Link to comment Share on other sites More sharing options...
Members mpoirier Posted June 6, 2011 Author Members Share Posted June 6, 2011 Phantom power is usually associated with low impediance condencer microphones, not guitar pedals. If someone wants to install a 9v power jack to a pedal so it can run off a 9vdc adaptor, thats a piece of cake. Running a guitar pedal off of 48v phantom power designed for a mic is more difficult and can be risky to the device the provides it due to current issues. If the pedal was designed for battery use only, its important you use a power supply that has no AC leakage so theres no hum. I suggest using a Dan Electro Zero hum adaptor or a Boss adaptor. Either will work on a pedal that has no additional filtering added so it will be hum free. Other adaptors may cause a bad hum. For the jack. You can install the standard DC jack or you can use a battery snap adaptor. The DC jack is a three way jack that has a switch in it that kills the power coming from the battery. Its hard to tell what mic was wanting to do from his original post. He sneeds to clarify what he's wanting to do, what kind of pedal, what kind of power etc. There is someone doing this mod and others : http://www.putnamguitars.com/mods.htm All I want is the phantom power through XLR for my Tech-21 Classic... PS: The Tech-21 Classic already has battery and 9v jack adaptor. Link to comment Share on other sites More sharing options...
Members Mr.Grumpy Posted June 6, 2011 Members Share Posted June 6, 2011 Phantom power is usually associated with low impediance condencer microphones, not guitar pedals. Yes, but as the OP explained, there are some pedals that do run on phantom power via an XLR cable. However, these are all DIRECT BOX type pedals that are meant to be plugged into straight to a recording console or interface, not a guitar amp. I have one of these Tech21 SansAmp boxes, and they work fine on phantom power. It's just a convenience thing, nothing more. I don't have to mess with an internal battery or external wall wart. Obviously you can't daisy chain effects, but in this application, it works great, because it's just: bass -->SansAmp Bass DI---(xlr cable)--->rec interface Unfortunately, modifying an existing pedal to run on phantom power won't be an easy/trivial thing to do. Sort of strange that the SansAmp character series pedals don't have that conveinent feature, because they are also made to run "direct" (all the character series pedals have speaker cab emulation), but I'm sure it costs extra $$ for the XLR connector and phantom-power circuitry. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted June 6, 2011 Members Share Posted June 6, 2011 Yes, but as the OP explained, there are some pedals that do run on phantom power via an XLR cable. However, these are all DIRECT BOX type pedals that are meant to be plugged into straight to a recording console or interface, not a guitar amp. I have one of these Tech21 SansAmp boxes, and they work fine on phantom power. It's just a convenience thing, nothing more. I don't have to mess with an internal battery or external wall wart. Obviously you can't daisy chain effects, but in this application, it works great, because it's just: bass -->SansAmp Bass DI---(xlr cable)--->rec interfaceUnfortunately, modifying an existing pedal to run on phantom power won't be an easy/trivial thing to do. Sort of strange that the SansAmp character series pedals don't have that conveinent feature, because they are also made to run "direct" (all the character series pedals have speaker cab emulation), but I'm sure it costs extra $$ for the XLR connector and phantom-power circuitry. Yea thats what I was thinking as well. I'm just thinking by his post he is calling a wall wart, phantom power which is leading to confusion. You never know though, it may be he wants to use phantom power from a mixer of presamp or something like that. Its not worth the cost to do a conversion to 9v tp power a pedal nor is it safe. You can buy a wall wart cheaper than the conversion for sure. A Dan Electro is $9 and change and wont have any hum issues. If its multiple pedals, the Spot One works like a champ. Adaptors for a battery clip is cheap as well. Link to comment Share on other sites More sharing options...
Members mpoirier Posted June 6, 2011 Author Members Share Posted June 6, 2011 Hi, I don't know why but I posted twice here to explain What I want to do but the messages do not appear because they need approval from administrator... (?) Anyway, here we go again, and sorry for my "wording" english is not my native language... First, the Tech-21 Classic already has battery and 9v jack for the adaptor ( commonly refered to as "wall wart" ) which I DO own. Someone does this mod and others : http://www.putnamguitars.com/mods.htm All I want is add the XLR with proper circuit to power my Tech-21 Classic with phantom power from the audio interface... I think it is pretty simple I don't know how to explain this more simple ! Anyways, here's what I found so far : http://sound.westhost.com/project51.htm Now I need the proper values to downgrade the 48V provided by the interface to the 9V needed by the pedal. No need to tell me I can do it some other way, THIS is the way I want to do it... Thank you if you have any help to provide for this project ! Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted June 6, 2011 Members Share Posted June 6, 2011 I get what you are going for now and it makes perfect sense. Before, I was thinking of the standard guitar->pedal->Amp configuration. Couple questions for you. Is there enough room for an XLR connector in the existing case? What is the currect draw of your stomp boxes, and what current is the phantom power on your interface rated for, they are generally pretty low current supplies. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted June 6, 2011 Members Share Posted June 6, 2011 You dont need to install an XLR connector. You use a stereo TRS jack, apply the negatuve power to sleeve ground, positive power to the ring, and the tip remains the signal. The mic cord you use would need to be converted to a stereo 1/4" jack. I couldnt find any schematics on the voltage stepdown, and I dont know if theres enough space in the pedal for extra parts. The system is simular to this http://www.dcvoltage.net/p3 except you would be getting the power from a mics phnatom supply. maybe you can find the schematics for the classic sans amp and the phantom powered one and determine what parts are used. My guess is theres a voltage regulator in there. You also have the issue of converting the high impediance output to low impediance to low. its an easy thing to do using a high to low transformer or DI box but you cant pass phantom through nor connect phantom to transformer. It would appear as a dead short the supply and blow it up. So you would have to convert High impediance to low using an active circuit that runs on 48vdc, then convert the voltage to 9vdc for the pedal. The diagrams you posted may be designed for this but I dont think so. You could just run the signal through the mic cable into the Preamp unbalanced and still get the sound through. Doesnt usually sound very good that way with umbalanced impediance. So theres two issues to deal with here. Impediance matching that needs to be done electronically and converting 48vda to 9vdc so the pedal will run. You would likely need a voltage divider or dual voltage regulator. Seems like an awful lot of work to me even if you have the space for the extra parts to do it. Link to comment Share on other sites More sharing options...
Members mpoirier Posted June 6, 2011 Author Members Share Posted June 6, 2011 I get what you are going for now and it makes perfect sense. Before, I was thinking of the standard guitar->pedal->Amp configuration. Couple questions for you.Is there enough room for an XLR connector in the existing case?What is the currect draw of your stomp boxes, and what current is the phantom power on your interface rated for, they are generally pretty low current supplies. There is plenty of room to add the XLR connector and other parts. Actually it is suspiciously empty ! I don't know the exact current draw of the pedal but the provided PS is rated 9V 100mA if that is an indication. The Presonus outputs 48V +/- 2V, and event though it is bus powered (firewire) I always use the provided PS rated at 16VAC 1000mA... But the show stopper right now is the impedence mismatch noted by WRGKMC. Although stepping down voltage is more simple I really did not think about "that" part and I don't think I want to mess with it... I guees I'll just continue to buy batteries... :-( Link to comment Share on other sites More sharing options...
Members katillac Posted June 7, 2011 Members Share Posted June 7, 2011 Let me know if I understand what's going on. You want to use a single XLR cable into the box that will provide power to it and provide the guitar out signal to the mixer, yes? Will the guitar input signal also be coming in from the mixer? How many pins will the XLR connector have? Will the voltage coming in on the cable be at 48v DC and need to be dropped to 9v DC? If that's it, I think I can whip something up. I was totally confused about the terminology of phantom power, but when you mentioned the XLR cable, it made more sense to me. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted June 7, 2011 Members Share Posted June 7, 2011 Let me know if I understand what's going on. You want to use a single XLR cable into the box that will provide power to it and provide the guitar out signal to the mixer, yes? Will the guitar input signal also be coming in from the mixer? How many pins will the XLR connector have? Will the voltage coming in on the cable be at 48v DC and need to be dropped to 9v DC?If that's it, I think I can whip something up. I was totally confused about the terminology of phantom power, but when you mentioned the XLR cable, it made more sense to me. Ever hear of a Sans Amp? Its a box used for direct recording. It has seitches and settings to emulate a miced guitar amp. Its got British, Tweed, Bass Trebble settings etc. Instead of using a wall wart to power it he wanted to be able to use phantom power from the mixer to power it instead of using a wall wart. That would require stepping the voltage down from 48VDC to 9VDC. Running the pedal through a mic cable like that adds a complication. The pedal outputs Line Level for recording, Not Mic level. The Impediance and gain wouldnt be right. Line level is 10X too strong for a mic input plus its unbalanced, Not balanced. You can convert High impediance to low with a simple impediance matching transformer or DI box. Problem is that transformer would short the Phantom power out, so you would need to balance the impediance electronically like a condencer mic does. So you actually have two circuits to deal with. One to match impediance and one to provide power to the pedal. The newer version of sans amp has this circuitry built in. Since the box is only designed to be used for direct recording, and not as a stomp box, that design would make sence because you would be using it to connect to a recording interface, Mixer or Preamp that usually contain phantom power. Pretty handy actually. Saves you from having to use a separate wall wart or battery to power the box. You would have to compare the circuit diagrams of the two versions of the boxes to find the differences in power division and additional impediance components to the box. Link to comment Share on other sites More sharing options...
Moderators AMZ-FX Posted June 8, 2011 Moderators Share Posted June 8, 2011 Phantom power works with microphones because: a) the current requirement of mike capsules is very low; andb) the microphone capsule output impedance is very low (50 - 200 ohms). The output of a pedal that was to be phantom powered would have to be very low impedance, or the resistors that are coupling the phantom power to the pedal would load down the output and reduce the frequency response. Also, the pedal could not draw more than a few milliamps so that the resistors could be high enough in value to reduce loading on the output. It is possible to phantom power a small pedal circuit but the effect really needs to be designed specifically for that type of power. regards, Jack Link to comment Share on other sites More sharing options...
Members katillac Posted June 13, 2011 Members Share Posted June 13, 2011 Phantom power works with microphones because:a) the current requirement of mike capsules is very low; andb) the microphone capsule output impedance is very low (50 - 200 ohms).The output of a pedal that was to be phantom powered would have to be very low impedance, or the resistors that are coupling the phantom power to the pedal would load down the output and reduce the frequency response. Also, the pedal could not draw more than a few milliamps so that the resistors could be high enough in value to reduce loading on the output.It is possible to phantom power a small pedal circuit but the effect really needs to be designed specifically for that type of power.regards, Jack Thank you, Jack. The way you worded that made it easier for me to come close to understanding it. Apparently this is way over my head. Link to comment Share on other sites More sharing options...
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