Is this a problem for re-amping?

Feb 8, 2008
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Ft Worth, TX
dc%20offset%20tracks.jpg


this is two different guitars plugged straight into my firepod, same input, same preamp level for each.

edit: first two tracks are my guitars, the 3rd one is GubbKuk's di i downloaded from this forum
 
Interesting that the valleys seem to be more pronounced than the peaks at times - otherwise Dan I'd say turn up the level on the Firepod preamp (you want it peaking at around -4 when you absolutely pummel the low strings) and it should be good! But of course, a good dedicated DI would be better, and I got the Countryman Type 85 I used for my DI test for like $120 on ebay!
 
Ok, I tried your advice with the 2 DI boxes I have. Here are the results:

dc%20offset%20tracks2.jpg


The Radial PRO DI Passive direct box clearly records the best transient responses! However, all of the DI signals still have the same DC offset. These tracks in the image above are all recorded with my ESP Eclipse. Whenever I record my friends PRS SE Paul Allender, there seems to be a DC offset in the opposite direction like in the first posted picture. I have also recorded several vocals with my firepod that have no offset. So it's safe to conclude that my DI boxes and my mic preamps are not causing the offset.

So, the only thing that must be causing this offset in the waveform, is the output of the guitar. :erk:

Has anyone ever seen this before with a guitar? How would I go about fixing this?
 
Hmm, not really sure, but I know the Radial Pro DI is definitely the best of the three options you have for active pickups (I've heard the BDDI is pretty crappy for guitar DI's, even with all the processing bypassed), though since it's a passive box, for passive pickups I'd rather use the Firepod cuz of it's increased input impedance (active pickups are less sensitive to input impedance of DI boxes, which is why the cleaner Radial would be my choice for them). As for the DC offset, not a clue unfortunately, but hey, if it sounds good, then that's what counts! ;)
 
AFAIK, DC offset only occurs in the AD converters. Not that that really answers your question.
 
The problem with recording directly into the firepod is that because of the DC offset, it either cuts or compresses the bottom half of the waveform, causing unwanted distortion. The gain on the firepod is also on zero when i record directly into it, the DI box gives me room to turn up the preamp gain for a cleaner signal.

So I will have to use the radial DI if i want the cleanest signal possible. Which still won't be that clean beacuse this DC offset is fucking up my headroom. Here's another Comparison i made with my Takamine Acoustic/Electric going right into the firepod.

dc%20offset%20tracks3.jpg


and no, i'm not going to re-amp my acoustic just cause the waveform looks prettier.

I wish I could just take my guitar to a shop to fix this, but I doubt any guitar tech would even know what the hell I'm talking about if I tried to explain it.
 
Is there a HPF on the DI box? For a workaround you could apply a HPF and bounce it to disk and replace before reamping. That should help.
 
i wish the firepod had s/pdif. i purchased the firepod years before i got my digi 002r. i'm basically just going from it's 8 analog outputs into the analog inputs of the 002 since the rack version only had 4 built in preamps.

i've come to the conclusion that this must be happening because of poor wiring in the guitar, possibly some bad pots or something.
 
i wish the firepod had s/pdif. i purchased the firepod years before i got my digi 002r. i'm basically just going from it's 8 analog outputs into the analog inputs of the 002 since the rack version only had 4 built in preamps.

i've come to the conclusion that this must be happening because of poor wiring in the guitar, possibly some bad pots or something.

I'd be willing to bet the DC offset is because you're running through 2 different Preamps and 2 different A-D converters.:err:

Try the DI direct into XLR input 1 of the 002.
 
Tried it, but that's good suggestion. It actually is only going through 1 preamp and 1 converter. The DI is going into it's preamp and it's output is a line out into the line in of the 002, so it stays analog. THEN it is getting converted to digital and sent to protools through the firewire. I'm basically using the firepod just as preamps, and the 002 just for A/D conversion.

If you look at my 4th post, I've plugged in both guitars to the exact same input with nothing changing other than the physical guitar itself, yet the ESP is sending out an offset signal compared to the acoustic/electric guitar.

I think i'm going to go to my friends house and record some DI guitar tracks on his m-box to see if his interface does any better. Surely it's possible that somehow the guitar wiring can effect how clean a signal the guitar will give out.