Portico 5016 DI/THRU Buzz Issue - Gain Staging Pehaps?

Hi there

I thought I would try something new to me with my Neve Portico 5016 yesterday and record 2 bass tracks simultaneously. The 5016 is a 2 channel unit with 1xMic Pre and 1x DI/Line Level.

My set up was:


1. My Fender Jazz Bass going into the DI then going into my RME Multiface 2 then into Sonar 7 PE.

2. The Fender Jazz Bass signal (unaltered?) simlutaneously being routed from the THRU ouput of the 5016 to my modest Fender Rumble 15 watt combo. This then having an SM57 pointed at the speaker cone going into my MIC PRE side of the 5016, this also going into the RME Multiface 2 etc.


When I tried to do the above, I seemed to get major noise issues with a constant buzz coming through the Fender Rumble combo which would get louder as I raised the volume. It also happened with a Marshall amp I have too. Therefore, we may rule out the amps at this point, for now anyway. I drove myself mad trying to get rid of this buzz which at times sounded as though it had a clock ticking through it. GGrrrr.

I am not an expert on gain staging. Therefore, if this is the issue I would be grateful for advice in solving the issue. I will describe a few things below:

My Bass guitar volume knobs were turned all the way up as this is something that I was always told to do. Was this good advice? If so, it certainly ties in with what I have read regarding that good gain staging requires that you get as much hot signal into the signal chain as early as possible?

Even with my DI on the 5016 turned all the way down, the Fender Rumble still buzzed. This was also the case with the MIC PRE turned all the way down also having the SM57 disconnected from the 5016. Therefore and in a nut shell, I'm getting the buzz from my Fender Rumble from plugging my bass into the 5016's DI (when turned all the way down or up a bit), whilst taking the signal from the THRU to the Fender Rumble. I am just totally stumpted as to why this has happened.

I tried the Fender Rumble in another room to no avail. Even my mouse on the mousepad was making sounds in the buzzing. If any louder I would have been able to mimic the record scratching breakdancing stuff from the 1980s using my mouse...lol

I tried switching to other guitar cables. Incidentally, I was using unbalanced mono cables from the Bass>>>5016 DI and from the 5016 THRU>>>Fender Rumble as the 5016's manual stated that the THRU takes an unnaffected signal to an external amplifier. I took this to mean that it did not convert the signal to balanced. I was also using XLR to 1/4 balanced between the 5016 and the RME Multiface 2. Not that this matters as the problem was pretty much pre-preamp and interface.

The Ground Lift Switch on the 5016 only marginally helped. However, this tended to affect the DI track. Therefore, everything was now buzzing as if I'd shared the buzz between the 2 tracks, lessening it in the process, this still being unnacceptable though. In fact, the only way I can get rid of the buzzing is to disconnect the THRU output completely and unswitch the Ground Switch and solely use the DI. This sucks after spending the kind of money I have on the unit.

I do not think the issue is the 5016 or Fender Rumbles proximity to each other or other gear as I also tried things quite spaced out.

Is there something I am missing regarding the intended use of the 5016 or something else? This is what the manual says:

THRU - An output Jack is provided on the front panel that replicates the D.I. input signal, appearing as an unbalanced source. This THRU Output may be used to feed an external loudspeaker amplifier. (Use a T.R.S. Tip-Ring-Sleeve or a single pole Plug).

Ground Isolation Push-Button switch - If hum or buzz should be heard, which might be caused when a separately powered and grounded guitar or instrument is connected, a Push-Button on the front panel lifts the Portico 5016 D.I. internal ground rail from the TRS circuit to break a potential loop. Such Loops are formed when separate grounded utility power outlets are used, for example on the stage for mixing or amplifying equipment.

Any advice on sovling this would be gratefully appreciated.


Regards

ZippInc

Ideas:

1. Fluorescent lights maybe?

2. Security system?

3. Shared power main (kitchen appliances and such)?


Solution: EBtech HumX (link)


I use HumX's for my home stufdio and for gigging, as it kills the buzz from ground loops and fluorescent lights, which most bars and other venues are full of.


-mr moon

Thanks everyone

I just checked and the UK dealer for HumX is just 70 miles from me. It looks like I'm going to have to try it out. Would you say the HumX is needed on my 5015 Pre/DI or on the Fender Amp? Or, both perhaps?

I ran some more experiments today. I put the Neve 5016 in a different room plugged into a wall socket all by itself. I used lots of different cables that I have. I even used a stereo cable which has one sheilded side and used as my Bass(sheilded side)>>>DI and and also tried reversing the cable so that the shielded side was going into mu DI. I then also used this cable as the THRU>>>Fender Amp, reversing this also...all to no avail.

I also turned the volume on my Bass all the way down and also turned my RME's Total Mix all the way down (not that that should matter) and also turned the DI down to its minimum. The buzzing persisted.

HumX here we come. I think a chat to the staff at Portico may on the cards too.



Thanks again

ZippsInc

ORIGINAL: newfuturevintage

I just checked and the UK dealer for HumX is just 70 miles from me. It looks like I'm going to have to try it out. Would you say the HumX is needed on my 5015 Pre/DI or on the Fender Amp? Or, both perhaps?

Probably won't matter, but I'd put it on the Fender if everything else is OK. Definitely sounds like an earth loop though.

Thanks for that. :)

"I think a chat to the staff at Portico may on the cards too. "

If you want to make it a fair chat be sure to inform them that you have ignored the advice to read the hundreds of articles on star grounding I provided a link too.

HumX type products are good for temporarily fixing a problem... but they are a sad substitute for learning how to properly ground your equipment.

Go read up about star grounds and learn to eliminate hum at it's source.

best regards,
mike

Here's the gist of the star ground story... the best solution for your buzz is too get a 50' (or shortest length you can use) 12 gauge extension cord and send power to your remote amps from the same wall socket your are powering your recording gear with.

It's not necessary if for example you are just using a mic to record a remote amp... because there is no electronic connection.

If you are working with a parallel direct connection as you describe then grounding becomes a possible issue... the best way to eliminate it is to practice star grounding... if you can't there are best practice ways to lift ground or use iso transformers etc.

But if you just use an extension cord (to create a star grounded power circuit) as I suggest your buzz will practically disappear.

all the best,
mike

great! BTW make sure its three prong... meaning it has a third prong.

best,
mike

No

Apparantly there are two HumXs which are plug adapters as you describe but one is designed for use with amps etc which are using XLR cables with other being for use with gear using 1/4" cables. I thought this to be slightly odd too but this is what the main UK distributor told me but then...perhaps the guy I spoke with isn't well clued up. This is why I decided to post here and check.

Cheers Mr Moon :)

Thanks Mr Moon

It appears I spoke with the wrong person when I got through to the distributor. He did say that the guy I was looking for was off sick.

Thanks for clearing that up for me. I'll give them another ring. :)


ZippsInc