Axiom Home Page Forums General Discussion Technical Questions Axom A1400-8 amp hum from Denon AVR-4306...

uhh!!!

This is the line card from Neutrik on "Combo" XLR/TRS chassis connectors.

http://www.neutrik.com/fl/en/audio/204_59540618/Combo_Series_productlist.aspx

They are all 3 pole on the XLR but some are 2 pole and 3 pole on the TRS.

Solid-State

http://www.neutrik.com/fl/en/audio/210_341930987/NCJ5FI-H_detail.aspx

This is what's used on the input board?

http://www.neutrik.com/fl/en/audio/210_1817827768/NCJ9FI-H_detail.aspx

and

http://www.neutrik.com/fl/en/audio/210_129149521/NCJ6FI-H_detail.aspx

on the TRS pins it shows T, R and S as well as TN, RN and SN what is this "N" about... please explain drawing if any of you understand. On the PCB version with TN RN and SN there seems to be six pins for the TRS alone! ugg it's way over my head

Solid-State

Solid-State

I would say they probably used something similar to the NCJ5FI-H.

There is no correct way to connect an unbalanced signal into a balanced input (without something to create the inverted signal). If you don't want to use the adapters, have an RCA to 1/4" mono phono cable made up.

The 'N' jacks are for use with things like headphones. Where inserting something into the jack breaks (or switches) the connection. When there is no plug in the jack the T and TN are connected so the jack can be placed before an internal amp. Inserting the plug opens the switch so the signal goes stops at the jack.

Owhh I get it ClubNeon. It's so a person can jack in say a guitar but prevent a momentary hum the instant the TRS is jacked in. I guess you'd use that model for a guitar amp. I'm now wondering if coax or two conductor "balanced" cable should be used.

From this new info, I take it the best cable for me to use would be a decent coax like Bluejeans LC-1 with Taversoe RCA on one end and a switchcraft 1/4" mono on the other. The tip shaft on the Switchcraft units are solid OFC copper as well as the sleeve with a silver plate. The included adapters are very poorly made and are hollow and the weight suggests they are made of aluminum or something with gold plate. No way they are made of brass they are simply to light.

Solid-State

OK I just took a hacksaw to the included adapters. They are made of aluminum with a VERY THIN coat of gold plate. WOW that's horrible man...

Man I wish Tom wasn't so obsessed with the piece's height. The long runs from PCB headers to the speaker terminals and input board sucks and you can't help but wonder about EMI/RFI on those and proper RCA jacks could have been used if it was made taller. Owh and no weird power plug on the bottom. Also looking at the preamp board it seems it has a series of through-holes unused (4pin header) and the ones that are (16 pin header) seem to have the pin header soldered in place that would put the header pins on the back of the PCB. I guess that's how the pre opamps connect to the amp boards? Some of the pins on that 16 pin header don't look like there is enough solder man. I haven't opened the thing up yet just using a flashlight and looking in there. I'm scared of opening the thing as I've never worked with any electronics with caps that HUGE. I'd be scared to bleed the thing. I can imagine the crack discharging them!

Solid-State

Since you're so very helpful in teaching us all about topography and stuff, do us all a favor so we know for future reference:

Power the unit up, let those caps just fill up, and stick a screwdriver in there while standing in a tub of grounded water.

We'll wait for your report.

That 16 pin header is of concern now. I've looked at it with my magnifier headset with very powerful light shinning into the chassis and I can see through hole pins on the header without a proper solder joint. Some are gray even and look cold! Others only have solder bead on one side of the through-hole! Perhaps 20% look right with a proper "dome" and shine. OMG I now am very upset again and feel HORRIBLE! Owhh and thanks for the comment Mark... Axiom if I open the unit to take photos of these solder joins will you void my warranty?

Solid-State

Board one for chan 1-2 looks ok with propper domes and shine. Board two is god awful with gray joints and a lot without enough solder or heat when made. You can literally see that the solder didn't bead around the pin as it's only on one side and you can actually see down into the PCB on one side of the pin where there is no solder! Boards 3 and 4 are 50% success rate pin to pin on the solder job! I'M SO UPSET AGAIN!