Bo Hansen DI layout

[Matt55]

Ok so as you asked nicely Treb.

Here are my builds.  They are not the neatest things I've ever built but they dont really need to be! They work beautifully and thats all that matters.

Thanks,

Matt

 

[Treb]

Nice clean builds Matt! BTW, why did you choose those beefy resistors?

 

[Matt55]

Nope and I wasn't expecting them but thats what comes with the standard Mouser BOM from the first page of the thread...

I noticed you used some upgraded parts in yours but I'd already ordered the BOM and thought that the transformer would make the most difference anyway so decided just to stick to standard BOM.

It was a nice surprise mind!

The little green terminal blocks make things so easy to dissassemble and re-assemble!! They are made by Phoneix if anyone is interested

Once again thanks to Bo, Volker and people who answered my questions in the thread. My brother loves them, they really make a difference to his acoustic live!

Thanks, Matt

 

[tagailog]

good day,

I just wanted to ask, how can you connect an external 48V phantom power to this circuit? because my mixer does not have a phantom power so i need to make an external one.

 

[Whoops]

good day,

I just wanted to ask, how can you connect an external 48V phantom power to this circuit? because my mixer does not have a phantom power so i need to make an external one.

Maybe it could be simpler to you in that case to just use a passive DI, then you would not need the 48V.

Otherwise you can buy something like this:
http://www.thomann.de/pt/millenium_pp2b.htm

It will provide 48V phantom power to DI's or condenser microphones, probably it will be useful to you so you can also use condenser mics with your mixer you case you need that.

 

[Treb]

good day,

i need to make an external one.

Do not make a 48 volt PSU yourself, buy one on ebay. Search for "cisco 48v psu".  Do not pay more than ~15 dollars/euros. These PSUs are generally capable of delivering 350-380mA. More than enough for this DI, as Bo says it only draws ~3.5mA.

I'm not exactly sure where to hookup 48 volts in the circuit so I'll let more knowledgeable people answer that question. You wouldn't want to burn down your house based on my uninformed advice... 

Interesting stuff to watch:
https://www.youtube.com/watch?v=6McmnSmiY5o
https://www.youtube.com/watch?v=3w067lYc8Kw

 

[Whoops]

good day,

i need to make an external one.

Do not make a 48 volt PSU yourself, buy one on ebay. Search for "cisco 48v psu".  Do not pay more than ~15 dollars/euros. These PSUs are generally capable of delivering 350-380mA. More than enough for this DI, as Bo says it only draws ~3.5mA.

I'm not exactly sure where to hookup 48 volts in the circuit so I'll let more knowledgeable people answer that question. You wouldn't want to burn down your house based on my uninformed advice... 

Interesting stuff to watch:
https://www.youtube.com/watch?v=6McmnSmiY5o
https://www.youtube.com/watch?v=3w067lYc8Kw

Phantom power 48V is supplied to Pin2 and pin 3 of the XLR output connector of the DI.

as I've posted before the best solutions would be an external phantom power supply like this one:

http://www.thomann.de/pt/millenium_pp2b.htm

 

[Bo Hansen]

As Woops say, buy an external Phantom PSU, there are many good and inexpensive types/brands.

They are complete with balanced XLR connectors in/out and some of them can operate with both battery and 120/240 volts via adapter.

If you buy a two-channel version, then you have power for one more DI-box or a condenser microphone.

Another option is to make a simple modification and operate the DI-box from a 24 dc volts regulated/stabilized power supply.
50 mA (ore more) current capacity is enough for several DI boxes.

But it must be active stabilized, it is not enough with a regular guitar effect pedal psu.

The modification consists only to remove the two 6.8 k resistors and connect the stabilized 24 volt positive lead from the PSU to the now free end of the LED, (before thejunction of the two resistors) and the minus lead from psu to 100 uF minus side. (pc-card electronic ground)

--Bo--

 

[tagailog]

i think i need to buy and external PSU... thanks for the input guys...

 

[Erazorblade]

Hey guys,

I've got a question, maybe you can help me.
I recently build the DI with a Haufe transformer and the pcb available on the forum here but every guitar i plug in sounds distorted when hitting the strings harder, it seems the signal coming out in the end is too hot/loud. I checked the pcb, but on the first look everything seems to be OK. Is there anything i can check or something?

Thanks!

EDIT: Soldered everything again, but now the output is far too low...

 

[Treb]

Did you do the voltage checks? What are your readings?

input ground -> LED :  ? volts (should be +24 volts, +/- 1 volt)
input ground -> junction of 3,9k resistor etc. : ? volts (should be +12 volts, +/- 0,5 volt)

 

[Erazorblade]

When plugging in a guitar and playing, the output is really low. Need to push the preamp to maximum to even hear a signal (noisy).
Also the Amp-out is really low/not present.

Somehow when plugging in the guitar in the Amp-out i get a louder signal on the XLR-out than using the Input, but still far too low.

I checked again the voltages between

ground input and Jumper = 24V
ground input and 100nf capacitor=24V
ground input and left side of 3.9k Resistor=13V
ground input and emitter of BC560=13V

I opened the DI and made some pictures:

http://www.bilder-upload.eu/upload/2419ea-1456243879.jpg

really dont know what to do know. Trying to fix it for 3 days now  :-\

 

[Mondy]

Hi Erazor

Cannot tell if you have added the wire link on the board if you are not using the LED indicator?

Also do you have your 1/4" jacks wired correctly?

 

[Erazorblade]

Hi Erazor

Cannot tell if you have added the wire link on the board if you are not using the LED indicator?

First of all thank you for the answer
I did not use a LED, i just used a normal wire.

Also do you have your 1/4" jacks wired correctly?

i am using the lumberg mono jacks.  After trying different things i ended up connecting the sleeve  to the ring to GROUND and the tip to +.

The ring usually is not needed here, but should not make any difference because on a normal instrument cable the ring=ground, or am I wrong?

 

[Treb]

The input and output jack sockets must be isolated from the metal enclosure for the ground loop suppressor to function properly. Right now you have input and output grounds connected to the enclosure by the looks of it. Use plastic jack sockets to prevent this.

What's the tolerance of those two 6.8K resistors? That gold band usually means 5%, the BOM (and the PCB) specifies 1% for those two resistors.

 

[Erazorblade]

The input and output jack sockets must be isolated from the metal enclosure for the ground loop suppressor to function properly. Right now you have input and output grounds connected to the enclosure by the looks of it. Use plastic jack sockets to prevent this.

What's the tolerance of those two 6.8K resistors? That gold band usually means 5%, the BOM (and the PCB) specifies 1% for those two resistors.

Thanks for the answer Treb!

I now added the right Resistors with 1% tolerance and checked the voltages again.

For now I don't have any plastic jack sockets, but I tried to let my jack input&ouput hang out of the DI (not touching the housing), what - if I didn' t get you wrong - would be the same as having the plastic jacks in the DI.

Unfortunately everything stays the same...  ???

 

[Treb]

Your image hosting site is being blocked (potential malware etc.).  I suggest you first buy the proper plastic mono jacks sockets and hook them up per Bo's instructions. With regard to wiring, try to use different colour wires for ground and signal. Makes troubleshooting off of a picture much easier. How are your soldering skills? What does the solder side of the PCB look like? No solder bridges? Check the resistors, are the correct values in the correct locations? What transistors did you use?

Please DO read the techpage instructions Bo has so excellently compiled, follow those, work methodical and your DI should work flawlessly. Mine and many others' did. Good luck!

 

[Erazorblade]

Your image hosting site is being blocked (potential malware etc.).  I suggest you first buy the proper plastic mono jacks sockets and hook them up per Bo's instructions. With regard to wiring, try to use different colour wires for ground and signal. Makes troubleshooting off of a picture much easier. How are your soldering skills? What does the solder side of the PCB look like? No solder bridges? Check the resistors, are the correct values in the correct locations? What transistors did you use?

Please DO read the techpage instructions Bo has so excellently compiled, follow those, work methodical and your DI should work flawlessly. Mine and many others' did. Good luck!

Thank you for the answer Treb. Soldered everything again, checked BO's techpage carefully and added the plastic jack sockets. Seems to work fine now, only one last thing I noticed.

When i move my finger near/around the guitar pickups i can hear an increase of noise coming out of the DI.
When i touch the metal case with my other hand the noise is gone again.
When i touch the strings the noise is gone too.
When there is no guitar plugged in there is no noise at all.

Seems to be a grounding issue?

 

[Treb]

The noise issues you describe are normal. In an electric guitar (and bass) the strings are connected to ground, usually by a wire connected to the bridge. Just keep a hand on the strings to eliminate the noise.

 

[Erazorblade]

The noise issues you describe are normal. In an electric guitar (and bass) the strings are connected to ground, usually by a wire connected to the bridge. Just keep a hand on the strings to eliminate the noise.

ahh, yeah i see..
But in comparison to my Radial JDI it's noisier. I've read that this could be improved by shield the parts/cables?
Just out of curiosity.