avedis MA5 & API lunchbox => noise

[karumba]

hey guys,

i've got a problem with my new API lunchbox & the avedis MA5 preamp. the preamp is quite noisy compared to my other preamps. i did a search here & found some threads pointing to a so called "Pin 1 problem".
what does this mean & (the more important question) how can this fix the noise problem?

thx in advance + greetings from germany!

[useme2305]

just bought an ma5 that i'm using in an a-designs 2 space rack. no noise problems what so ever.

[cinealta]

Email Avedis. He's a really helpful guy.

[karumba]

Originally Posted by cinealta

Email Avedis. He's a really helpful guy.

already did that 2 days ago, but he is at musikmesse right now & i don't expect to get an answer before start of next week.

[TonyBelmont]

Originally Posted by karumba

hey guys,

i've got a problem with my new API lunchbox & the avedis MA5 preamp. the preamp is quite noisy compared to my other preamps. i did a search here & found some threads pointing to a so called "Pin 1 problem".
what does this mean & (the more important question) how can this fix the noise problem?

thx in advance + greetings from germany!

Noise problems can be result of almost ANYTHING... I think it would have been better to wait for Avedis to help diagnose your problem because people here will have you running around in circles. Virtually no one here will be able to diagnose your problem (especially with what information has been given). If you can't get Avedis on the phone, call the person you bought it from for help. That's what dealers are there for.

All I will add is this: The MA5 is quite low noise, and I would wager you have a problem elsewhere. Good luck!

[sandking782]

How do you connect the lunchbox to your DAW? Try switching the module to another channel to check.

I have some noise issue with my API mic pre, turns out to be a cable issue (due to my own bad soldering).

[karumba]

thx for your help. avedis replied to my mail & my dealer - which is also @musikmesse - is already in contact with him to get a fix.

some info from avedis:
"Its a pin 1 problem in the API rack..the xlr pin 1 needs to be routed to chassis ground, not audio ground which is how it is now. I have talked to API about this as well. The reason why it is most noticeable with the ma5 is because it uses more active/ amplifier gain whereas most preamps are opamp driven and have a higher step up transformer. Any noise in the grounding system and the ma5 will reveal it more."

i'll post again when & how the problem is fixed, so other users can use this information as well. thanks!

[hereticskeptic]

Which API Lunchbox had this issue with the MA5, and how was your problem resolved?

[karumba]

sorry for the late reply. unfortunatly even the technician could not resolve my problem, so i exchanged my MA5 with a neve 1073lb. it was the 6slot lunchbox from API.

[caspar]

Strange ... I have 2 MA5s in a 6-slot Api Lunchbox (B-series). No noise problems here...

[nosebleedaudio]

Originally Posted by karumba

thx for your help. avedis replied to my mail & my dealer - which is also @musikmesse - is already in contact with him to get a fix.

some info from avedis:
"Its a pin 1 problem in the API rack..the xlr pin 1 needs to be routed to chassis ground, not audio ground which is how it is now. I have talked to API about this as well. The reason why it is most noticeable with the ma5 is because it uses more active/ amplifier gain whereas most preamps are opamp driven and have a higher step up transformer. Any noise in the grounding system and the ma5 will reveal it more."

i'll post again when & how the problem is fixed, so other users can use this information as well. thanks!

Pin 1 should connect to AC ground and Audio ground at some point...I connect them on MY JMK Supply...It has NOTHING to do with gain...
Know this: Pin 1 and Audio ground Must be connected together OR Phantom will NOT work...
The where and why's are VERY important...

By the way I design and build my own Power supply's and pres, and I modify every API Lunchbox I buy...The older ones..

The where and why's are VERY important...

[avedis]

I don't want to repeat what is already said here but I'll go over it in case it invites a question or two. I'll also add a few points -

*The XLR's shield is pin 1 which should connect to the chassis of the rack/lunchbox. In the 500 format, this is also pin 1 of the connector. Any noisy currents that get on this shield flows through chassis first (not audio ground) before it's connection to audio ground and common at ONE point - like Mike said above

*At one point, somewhere you think electrons would like to have a meeting and take a journey back, there should be a good connection between Chassis (pin1) and Audio Ground (pin5), Common (pin 13). Audio Ground and Common are normally connected inside each module and that's fine as it keeps ground impedance low by using two separate pins. And circuit board traces for all grounds should be thicker, not hair thin like I've seen.

*If the 500 module has a connection internally between chassis and audio ground/common, then it compromises the ground for all modules, even if you have a well ground-designed rack. This is why I am somewhat dissatisfied with the 500 format with the alliances.. these things need to be checked before being approved.

*I don't want to cause an alarm. Most owners of 500 racks and lunchbox's don't have a noise issue at all. Everyone's place is different, with different routes that electricity takes.

*Adding power regulators/conditioners may or may not help. Sometimes it makes things worse by increasing the impedance to the safety ground and dumps noise into it as if safety ground is some kind of black hole abyss.. IT'S NOT. Electrons don't just disappear into nothingness; they get transferred around.

*Noise seldom comes from "dirty power". Don't believe the hype. If your building has bad power, old wiring, inadequate safety, hire a qualified electrician and do it right, to CODE, instead of spending a bunch of money on conditioners.

*Sometimes the wiring is good but there is a field of noise (EMI, RFI) that couples into the mic pre's circuit, particularly the input transformer. In this case, monitor the noise as you move the unit around, or shut things off around it looking for a change. If there's change in the noise, you're getting warmer.

*Keep your power distribution (furman's and such) simple and safe. For example, don't tie wrap your AC cords to the metal chassis of the rack, especially nicely parallel to it in a bundle. This will help induce 60hz into the metal rack that your equipment calls Chassis Ground, and could be a source of noise if flowing through Audio ground first, as in the API lunchbox.

*Be mindful of what is above and below each piece of gear. Sometimes a toroidal transformer in a power supply in one gear will cause noise in a mic pre racked below it, because the input transformer is situated there. Turn everything on and check how noisy it is before you dedicate that space in your rack for that gear.

... I could go on with more.. understandably boring stuff to learn but ask questions if you have any and I'll try my best. There's some smart people here that could answer them too.


Avedis

[imacgreg]

Avedis, brilliant stuff we allllll should know. We call ourselves engineers, right?

[mortimersnerdy]

Hmmmm.....well, I was just about to buy a used Lunchbox/MA5 combination for sale on here but now I don't know. Is this just a 50/50 chance of having an issue, or is it guaranteed? My only other 500 rack is an OSA, and Avedis states on their site not to bother because of various issues with that rack.

[turk sanchez]

I have an ma5 in the new/current API lunchbox, and I also had another ma5 along w/this one (couple years ago) in the older API lunchbox. I also have put the ma5's in the 500hr and el500 as well.

I have never had any noise issues...even with tons of gain.

[mortimersnerdy]

cool. i'm trying to score a used 500hr & ma5 now.
we'll see how it goes.

thanks for the info.

martin

Originally Posted by turk sanchez

I have an ma5 in the new/current API lunchbox, and I also had another ma5 along w/this one (couple years ago) in the older API lunchbox. I also have put the ma5's in the 500hr and el500 as well.

I have never had any noise issues...even with tons of gain.

[Mark Kano]

Full API Lunchbox with MA5 here also... no noise problems whatsoever...

[analogjeff]

same here... no problem whatsoever with noise in the MA5... gorgeously clean, in fact...

[Fonk]

... and the same here.

[jrides]

Had this combo with no issues in the past. Recently bought it again. I suspect there will be no issues this time, as well.

Sent from my Droid using Gearslutz.com

[shamrock]

Been using a pair of MA5's in an API lunchbox with a LaChapell 583e and a Retro Doublewide with no power or noise issues at all.