Loud hum on S.E.X. 3.0

[roycruz23]

I just finished wiring up my S.E.X. 3.0 kit, I checked resistance and voltage values and they are
within range/values as listed. I noticed a loud hum. Please help.

Thank you,
Roy

 

[fullheadofnothing]

Does the position of the volume pot affect the hum?

What is plugged into the input?

What is connected to the output?

Can you post photographs of your build?

 

[Doc B]

It's quite possible that you have missed a ground connection at the input jacks or volume control. Maybe start by inspecting those connections for a missed solder joint. For that matter, look them all over. It may be that a connection was in contact long enough to pass voltage checks but worked loose after that.

 

[roycruz23]

The hum gets louder with the increase in volume.

My set up is Macbook/iTunes-->ARCAM DAC-->Hagerman Clarinet Tube amp-->S.E.X. 3.0. I use this set up
with my Hafler DH500 and loudspeakers without issues. I tried eliminating Hagerman tube amp and direct output
from ARCAM DAC to S.E.X. 3.0 but still the hum is present.

I am thinking the CAT6 cable is doing that, because I ruined the CAT5 that comes with
the kit. So I used a differrent one, a CAT6, the build is similar to CAT5, the difference is
in CAT6 each of the 4 twisted pair (stranded copper wire) is wrapped in foil, and all together shielded with coaxial-type
wire. How do I get a new length of CAT5 that comes with the kit?

The site can't accept 15 pictures of my work.

Thank you,
Roy

 

[Paul Birkeland]

I am thinking the CAT6 cable is doing that, because I ruined the CAT5 that comes with
the kit. So I used a differrent one, a CAT6, the build is similar to CAT5, the difference is
in CAT6 each of the 4 twisted pair (stranded copper wire) is wrapped in foil, and all together shielded with coaxial-type
wire. How do I get a new length of CAT5 that comes with the kit?

This is not the issue.  CAT6 is a higher bandwidth version of CAT5.  Both can be shielded/unshielded.  Neither is going to magically cause your amp to hum.  Unfortunately, you have replaced the solid core CAT5/6 wire we provided with stranded CAT5/6.  In our previous experience, this can cause some reliability issues down the road if all the strands are not well captured in each joint.

The site can accept 15 photos, you may just need to put them in 2-3 posts.

Are you using the SEX amp with speakers or headphones?  Which model(s)?  Which Arcam DAC are you pairing the SEX with?

Within the couple of photos you've posted, all I can see is that the diodes on the "H" terminal strips need to have their leads trimmed where they come out of the back of the terminal strip.

 

[roycruz23]

I use headphones. I have no plans of using this amp with speakers. Matter of fact, I wanted to bypass
S.E.X. potentiometer and use my Hagerman Clarinet tube preamp as the control.

My set up is- Macbook/iTunes/USB out to V-Link 192-->ARCAM irDAC-->+/- Hagerman Clarinet tube preamp-->S.E.X.

I am sending pictures on installment.

Thank you,
Roy

 

[roycruz23]

more pictures

 

[roycruz23]

another installment

 

[Paul Birkeland]

With no source plugged into the SEX, is there any hum?  What model of headphones are you using?

 

[roycruz23]

Let me try that one. I am using Grado SR125

 

[roycruz23]

Yes. the loud hum is gone with out a source. But how can I enjoy this without a source...

 

[Paul Birkeland]

Yeah, this can happen with a lot of components leading up to the SEX (or any of our kits for that matter) that are all ungrounded.  There are two paths to get you up and running:

1.  Run a clip lead from a metal chassis screw on the SEX to the metal chassis of each of the components between your computer and the SEX.
2.  Get a DAC that has a 3 prong power cord that plugs into the wall.

We are happy to help with whichever direction you'd like to go.

-PB

 

[roycruz23]

I sure will try that. One more thing, I mentioned I had no plans of using S.E.X. amp to
drive speakers and use the potentiometer for that matter. How dow I wire the fixed resistors?

Thank you,
Roy

 

[Tom-s]

Use 100k Ohm resistors from + to ground and - to ground at the RCA jacks.

 

[roycruz23]

I tried running my Arcam irDAC both with the supplied wall wart power supply and a power bank (MAXOAK) with 12V DC, 1.5V DC output. The power of V-Link also comes from the power bank (1.5V DC). I also run a ground wire on both Hagerman preamp and S.E.X. I tried running with and without the Hagerman tube preamp, but the hum is still there. Any thoughts?

Thank you,
Roy

 

[Paul Birkeland]

You can cable everything up, then start by removing the device furthest from the SEX in the chain, then the next, then the next, until the hum goes away.  Let us know which device that is (it could be your computer).

I do not recommend taking the pot out.  If you turn it up all the way, it just becomes a pair of 100K carbon resistors.

 

[roycruz23]

My conclusion is;

1. I turned on the S.E.X. 3.0 and listened without any input or attachment (RCA cable for this matter) and
    it was quiet (no hum).

2. I inserted/attached R/L RCA jacks from one end of the RCA cable, the other end IS NOT connected to
    any source at this time, it was quiet (no hum) when both jacks are inserted and secured, the only
    time I would hear the hum is when I am inserting it.

3. I noticed when I insert/attach the other end to a source (any source for this matter and I tried it when the source
    is turned ON and turned OFF), I CAN HEAR THE HUM.

4. I tried to detach/take off the L/R RCA jacks from the source, I noticed the same hum is present when I touch both ends.

Thank you,
Roy

 

[Paul Birkeland]

Try using your phone as a source.

Are the AC outlets where you live grounded?

 

[roycruz23]

Yes, wall outlets fits 3-prong plug. I think it is standard here in Livermore, California, U.S.A.

 

[Doc B]

Is all of the gear plugged into the same circuit?