Gearslutz - Firepod noise floor, fixed!

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- Low End Theory (https://www.gearslutz.com/board/low-end-theory/)

- - Firepod noise floor, fixed! (https://www.gearslutz.com/board/low-end-theory/475494-firepod-noise-floor-fixed.html)

I just did the spid/f mod on the FP and it got rid of the low end hum on my speakers. Wicked!

Quote:

Originally Posted by tenkas (Post 5215204)

This is info I have found a year ago... I just copy pasted it in a text file and do not have the sources... I believe it was on the presonus forum, you can probably google it.

Guys I thought some of you FIREPOD users might run into this problem and I finally found the fix after two times sending the unit back to Presonus and coming back from them with Problem Not Found:

Ok Folks!
here is the fix. it is an easy one and as expected, a ground loop (I know - I had to battle this in my amps...)
1. Take the case off your Firepod. You need a Phillips screwdriver and a 1/2" hex socket for the rear jack nuts.
- There are 2 screws on the top, 2 on the bottom and 3 on the rear (the S/PDIF and the two MIDI mounting screws) .
- Remove the 16 rear jack sockets with the 1/2" hex socket.
- remove the two side brackets.
- Disconnect the Power connector from the PCB board.
You are cleared now to carefully slide the case out:

2. Now... can you can see that S/PDIF socket? Can you see the metallic part that is between those two RCA connectors? BINGO!!!

THAT IS THE CULPRIT!!!
When the case is on, it creates a groundloop that induces the hum by touching the case and it needs to be isolated...
This is confirmed by Presonus as beeing an issue on older (2 years ago) Firepod construction that apparently was fixed at one point using an S/PDIF socket that doesn't have that metallic part, or something similar).
The metallic part does NOT have to touch the case by any means since it does not have any electrical use at that point.

--->>> continuing in the next post since I am allowed to only post 4 images per post...

continuation from previous post...

3. So, I simply used masking tape to isolate it from the case:

4. I mounted the case back (don't forget to connect the power connector back in its place in the PCB board), using all the screws BUT THE S/PDIF one and VOILA!
NO MORE HUM! Problem solved!

Wanted to post this here knowing of the fact that there are Firepod owners that have the same issue, and hopefully this way providing an easy fix - enjoying this way a hum-free excellent piece of gear!
Cheers,
Gabi.

Can someone confirm this?

I'm having a groundloop issue whenever I want to plug in a guitar and I just can't seem to get rid of it. Signal chain:
GTR (tried several) -> PreSonus FirePod -> 2x Phonic P6A Monitors or headphones (no difference)

I tried ungrounding everything and to ground everything. What do I need to unground here:
- Laptop
- Firepod

The problem is fixed when I put my pedalboard after my guitar, but I dont always want that.
To clear this up: the noise in this thread is just the regular noisefloor, right? I've actually just seen this post (the one I quoted above) regarding the groundloop. Before I want to open it up, I actually want to know if there's anything I'm doing wrong. It might just be the way I've got it hooked up.

I haven't noticed a difference after the SPDIF mod, what DID make a big difference is swapping the supplied adaptor for a 21V 3.3A DC adaptor; low hum is gone then.

Quote:

Originally Posted by heva (Post 7296007)

I haven't noticed a difference after the SPDIF mod, what DID make a big difference is swapping the supplied adaptor for a 21V 3.3A DC adaptor; low hum is gone then.

With low hum, you do mean a groundloop, right? Just to be sure ...
And which adapter did you get exactly (seeing as I'm from the Netherlands as well)? I'm seeing so many different ones being mentioned ... I thought someone said 21V 2000mA

Quote:

Originally Posted by DemoColorScheme (Post 7296009)

My mistake, it is a 12V 6A DC unit from an LCD tv (which is dead).

Quote:

Originally Posted by heva (Post 7296420)

My mistake, it is a 12V 6A DC unit from an LCD tv (which is dead).

Okay, so seeing you're in the Netherlands as well and this one seemed to have completely solved your issue: I'd love to know which power supply this is and where I can order it so I can be absolutely sure I'm gonna get this fixed.

It's from an MT-logic TFDVD-2318 LCD tv; part no. of the adapter is SAWA-02-598.
Most important seems to be the higher ampere value AND if the connector fits.

Makes sense, yeah. I think any 12 VDC 600+ mA power supply would probably work.

Quote:

Originally Posted by heva (Post 7296007)

I haven't noticed a difference after the SPDIF mod, what DID make a big difference is swapping the supplied adaptor for a 21V 3.3A DC adaptor; low hum is gone then.

To get back to this: while I love to get rid of the noisefloor, that's not my biggest concern. I need to get rid of the buzz, the groundloop. If I touch my guitar strings I hear this electrical pop. And when I put my face on the chassis of my rack case, I get a little shock. It's always been that way, though, no matter if I ungrounded all the gear or not.

I just want to be sure that noisefloor / groundloop don't get scrambled in this topic. So, heva, did you have a groundloop issue (buzz) or just some regular noise?

I'm a bit at a loss ...
I have no clue which power supply to buy here. 19VDC 3900mA? Can the Firepod get by with less? 12VDC? 15VDC? 18VDC? What does the Firepod actually need? Can I use DC or AC? Stabilized? Unstabilized? Which does it prefer? Etc ... I would love someone to help me out here.

In my FP10 I heard a ver soft 'hum' (in dutch: bromtoon), I don't know where it came from, but searching the net I've found the S/PDIF mod as well as suggestion to use a DC adapter. The latter did the trick for me; the FP10 specifies at the adapter plug that is can use 12-24V DC, so anything in between goes. I took the LCD adapter which is 12VDC and 6A with a fitting connector, hooked id up, switch FP10 on, and raise mic-pres to max: hum was gone.

Maybe check this

Quote:

Originally Posted by heva (Post 7306167)

I see! The link is broken, though. Kinda curious to see what you linked.

Hama netbook-netvoeding 19V / 48W

find it via: Home > Computer & Kantoor > Laptops > Laptop accessoires > Laptop-stroomvoorziening > Notebook > netvoeding

Quote:

Originally Posted by heva (Post 7306368)

Hama netbook-netvoeding 19V / 48W

find it via: Home > Computer & Kantoor > Laptops > Laptop accessoires > Laptop-stroomvoorziening > Notebook > netvoeding

I see! Well, I'm gonna give it a shot! Let's hope it works. €30,- is a bit much for me at the moment, so let's keep our fingers crossed.

Hum Issue (assuming ground)

Product: FP10 w/ S/PDIF separated with tape
Chain: FP10 > TRS - XLR > Yamaha HS50M
Power Setup: Furman SS-6B Steel Power Strip, 6 Outlets, 15 Foot Power Cord, Standard Level Power Conditioning, PC, Monitors, FP10, Display
Issue: Ground Hum
What I've noticed: w/ Firewire connected (hum)
w/ Firewire connected (no hum

I am losing my mind....any help is appreciated...

oh, the Power Supply for the FP10..

ITE POWER SUPPLY
MODEL: U150200AA4
INPUT: 120VAC 60Hz 0.4A
OUTPUT: 15VAC 2000mA

again Thank you to everyone who HAS or WILL post.....