Speck X-Sum - Hum Issues

[Siegfried Meier]

Hey gang!

We've owned an X-Sum for 13 years now - it started out as a guitar tracking mixer, then went off to reverb returns duties when we got a console. Recently, I had the bright idea to start using it to accept multiple sources from the control room and then feed our Dangerous Monitor unit as well as the studio floor headphones - a final pre-mixing station for various converters, consoles and other sources. I don't know what else to try, but all I get is mad hum anytime the Speck is wired to the Dangerous. Just to make sure I wasn't crazy, I ended up swapping out an ancient Mackie 1402-VLZ Pro (the last grey US made ones) just to test it all and what do ya know, not a single ounce of hum...there's barely even any hiss on the main outs, it's just dead quiet and does it's job.

Now, the Speck is an incredibly expensive piece of gear and it pains me to think that the $50 Mackie (used I paid) does the job better. I've tried an Ebtech X-Hum on the unit (as well as the Dangerous), I've tried a Radial Jensen iso unit (helped a bit, but hum was still noticeable, and I would need one on every output of the Speck - x 3). I'm assuming the Dangerous and the Speck both have very minimal components in their audio path which likely have to do with this hum, whereas the Mackie has all sorts of coupling caps and crap in the way to make people hate them...but man, it irks me that we can't make this work.

Any thoughts would be much appreciated on this.
Thanks!
Sig

 

[scott2000]

The manual makes a pretty big deal about it's proximity to other noise inducing equipment and even cautions about hum and buzz while hooking things up. Has it been moved since the change in it's task?

 

[Newmarket]

I took a look at the manual. It has an unusually heavy emphasis on interference / noise / EMI / RFI etc.
It's almost as if they know they are likely to have more problems than usual ?
Given that, it's somewhat disappointing to read in a manual from 2006:
"It is recommended that the shield be attached to the common (ground) at one connector's end, and the shield not be connected at the other connector's end. It is recommended that all shields be connected at the mixer end, and the shields not be connected at the other ends (synths, effects, power amps, etc.)."
It (or other "ground lift" solutions) may sometimes be pragmatic but it's certainly no longer the preferred method of interconnection.

 

[Siegfried Meier]

Exactly...all those "ground life" solutions they claim feel very old...I'm surprised, and it's still a current product for them.

I've ordered a few Radial Twin Iso units to see if I can fix some of these issues, but I don't think I'll be cutting off any grounds from the inputs...might as well use a Mackie at that point for what I'm doing.

It never had any hum issues in the old manner that we used to use it - for a mic in/guitar tracking mixer and then as a reverb returns unit. I'll report back! Thanks.

 

[Siegfried Meier]

Just reporting back! Got a couple of Radial Twin Iso units - the nice ones with the Jensen transformer - and there is absolutely zero hum now on the main outputs. I got another one just in case the B bus or the post-fader Mix A output gives me issues, as I'll be wiring up all the ins and outs of the Speck to the patchbay as well for maximum flexibility, but it's shocking how clean and clear the signal is now. Even cranking individual channels on the speck to +12dB barely exibits any extraneous noise...something not ever possible with most consoles or little mixers.

They should really just stick a Jensen and a ground lift into the box...but it's unlikely to fit, that thing is pretty darn crammed as it is. At least mention this as a fix in the manual!

Thanks guys,
Sig

 

[j.colt]

Speck gear is really fantastic. I have the X.Sum and a LiLo. They are incredibly clean with a bottomless noise floor.

 

[MisterCMRR]

Just reporting back! Got a couple of Radial Twin Iso units - the nice ones with the Jensen transformer - and there is absolutely zero hum now on the main outputs. I got another one just in case the B bus or the post-fader Mix A output gives me issues, as I'll be wiring up all the ins and outs of the Speck to the patchbay as well for maximum flexibility, but it's shocking how clean and clear the signal is now. Even cranking individual channels on the speck to +12dB barely exibits any extraneous noise...something not ever possible with most consoles or little mixers.

They should really just stick a Jensen and a ground lift into the box...but it's unlikely to fit, that thing is pretty darn crammed as it is. At least mention this as a fix in the manual!

Thanks guys,
Sig

Thanks Sig, It's nice to know that "going the extra mile" in the design of Jensen transformers is still appreciated!

Bill Whitlock. owner/chief engineer, Jensen Transformers 1989-2014

 

[Newmarket]

Problem sorted I guess. But would still be interested to know why the Speck kit without the Jensen's had the problem in the first place ?