A new happy Phase Linear / JBL owner

[Coldsmoke]

Hello everyone,

I hope you won't mind if I join... Let me introduce myself : my name is Florian, I am 33 years old and I am living in Brussels at the moment.
A few months ago I bought two pairs of JBL 4311 to hook to a Pioneer SA 9800 that I quickly changed for a PL 400 upgraded with the WOT rev D board with a PL 2000 as preamplifier. I am joining the forum with the hipe to find a solution to an horrible hum that I can ear when nnothing is played and even when the preamp is not connected (sounds like 50hz to me...) this problem is driving me nuts... I read dozens of pages about huming issues with this amp, but nothing helped me getting rid of this sound... When I tried it at seller's place, everything was working perfectly... I don't understand what is wrong with my set...

Thanking you in advance for your precious advises,

Florian

 

[Elite-ist]

Welcome Florian. You've come to the right forum to seek information for most, if not all, questions regarding Phase Linear gear.

Nando.

 

[Northwinds]

Welcome Florian!

Flip the plug?

 

[Gepetto]

Hello everyone,

I hope you won't mind if I join... Let me introduce myself : my name is Florian, I am 33 years old and I am living in Brussels at the moment.
A few months ago I bought two pairs of JBL 4311 to hook to a Pioneer SA 9800 that I quickly changed for a PL 400 upgraded with the WOT rev D board with a PL 2000 as preamplifier. I am joining the forum with the hipe to find a solution to an horrible hum that I can ear when nnothing is played and even when the preamp is not connected (sounds like 50hz to me...) this problem is driving me nuts... I read dozens of pages about huming issues with this amp, but nothing helped me getting rid of this sound... When I tried it at seller's place, everything was working perfectly... I don't understand what is wrong with my set...

Thanking you in advance for your precious advises,

Florian

First does it hum with NOTHING plugged into the input RCA Jacks?


If it does, look in the amp. If it does not, look elsewhere in your system.

Do you have any grounded plugs on your preamp or other equipment? Is any of your equipment connected to a broadband cable?

 

[gadget73]

If it is not external, I wonder what the power wire routing looks like inside. If its 50hz, it sounds like an AC mains wire is too close to an audio signal wire. If it was 100 hz, thats a sign of bad power supply capacitors.

 

[Coldsmoke]

First does it hum with NOTHING plugged into the input RCA Jacks?


If it does, look in the amp. If it does not, look elsewhere in your system.

Do you have any grounded plugs on your preamp or other equipment? Is any of your equipment connected to a broadband cable?

Wow, I wasn't expecting to have so fast answers! Thank you guys!
So, yes it hums with nothing plugged into the input RCA Jacks, I opened the amp once more yesterday but I can't see anything obvious ...

 

[Coldsmoke]

Welcome Florian. You've come to the right forum to seek information for most, if not all, questions regarding Phase Linear gear.

Nando.

Thank you Elite-ist !
I wouldn't like to pollute this section of the forum by the way, should I open a different thread in the approriate section ?

 

[Coldsmoke]

If it is not external, I wonder what the power wire routing looks like inside. If its 50hz, it sounds like an AC mains wire is too close to an audio signal wire. If it was 100 hz, thats a sign of bad power supply capacitors.

Hello Gadget,

I'll take a picture of the guts of my beloved amp tonight if it can help the investigation....
Thank you by the way,

 

[NavLinear]

Hello Florian,

Welcome to Phoenix! We're pretty laid back here so we don't concern ourselves much on what is posted where and if so a moderator will move this.

One of the first things to do if the hum is generated in the amplifier would be to tighten the bolts that hold the transformer to the chassis. You'll need to snug these down tight. I don't have a spec to reference the torque value but if you use a socket with a decent sized ratchet and hold the nut with a wrench that should work.

Another consideration would be the power cable - the original wiring was two pronged and it is important to plug this in correctly. If you have a three pronged plug the earth ground should not be connected to the chassis.

Oh yeah - I'd be remiss if I didn't welcome you with a Nav babe:

 

[laatsch55]

For those of us who actually have TO TURN A WRENCH NAV, it's commonly known the tranny bolts are 1/2" and a 13MM is a direct sub. SOA may be higher on the 1/2" though. BE voltage about the same. However if the 1/2" is made in China, a Craftsman 13MM is the better choice....

 

[laatsch55]

Hello everyone,

I hope you won't mind if I join... Let me introduce myself : my name is Florian, I am 33 years old and I am living in Brussels at the moment.
A few months ago I bought two pairs of JBL 4311 to hook to a Pioneer SA 9800 that I quickly changed for a PL 400 upgraded with the WOT rev D board with a PL 2000 as preamplifier. I am joining the forum with the hipe to find a solution to an horrible hum that I can ear when nnothing is played and even when the preamp is not connected (sounds like 50hz to me...) this problem is driving me nuts... I read dozens of pages about huming issues with this amp, but nothing helped me getting rid of this sound... When I tried it at seller's place, everything was working perfectly... I don't understand what is wrong with my set...

Thanking you in advance for your precious advises,

Florian

Florian , Welcome to Phoenix. We haven't had a good troubleshooting thread in introductions in a while so it's all good.

First, is it a hum through the speakers? Or an audible hum from the chassis?

 

[laatsch55]

Hello Florian,

Welcome to Phoenix! We're pretty laid back here so we don't concern ourselves much on what is posted where and if so a moderator will move this.

One of the first things to do if the hum is generated in the amplifier would be to tighten the bolts that hold the transformer to the chassis. You'll need to snug these down tight. I don't have a spec to reference the torque value but if you use a socket with a decent sized ratchet and hold the nut with a wrench that should work.

Another consideration would be the power cable - the original wiring was two pronged and it is important to plug this in correctly. If you have a three pronged plug the earth ground should not be connected to the chassis.

Oh yeah - I'd be remiss if I didn't welcome you with a Nav babe:

The torque spec is " just before it strips, quit..."

 

[Coldsmoke]

Hello again,

The hum is actually audible from the speakers, I quickly checked previously the tightness of the bolts on the transformer and they look to be tight enough (I did'nt dare to insist to much as my 13mm wrench was a bit loose, I thought these were imperial sized bolts...)

 

[laatsch55]

That are. They're 1/2 inch..

 

[Dazen1]

Welcome to Phoenix Florian.

 

[Northwinds]

Another consideration would be the power cable - the original wiring was two pronged and it is important to plug this in correctly. If you have a three pronged plug the earth ground should not be connected to the chassis

Did you check this Florian?

 

[P.L.F.]

Did you check this Florian?

Hi Florian, this is crucial what Northwinds says. You HAVE TO forget about grounding your amp through the 'earth' prong to your AC wall socket grounding. Provided you have 3-wire power cable (EU standard), two options there: either you disconnect the grounding wire inside your AC plug or you cut its connection to the chassis on the other side of the cable, inside the amp. Don't worry, your grounding 'will flow' through shielded RCA signal cables from your pre-amp or e.g. CD source (keep ONLY ONE gear grounded to your AC wall socket, closer to the source of your music, better...).

On top, if you have some cash to invest, try to google this device: "PS AUDIO Noise Harvester". On ebay you'd pay probably $60-$70. Not sure what's inside but this little thing does miracles to your multi-gear audio system, which is dead silent after plugging into the same AC wall socket... Checked myself...

 

[marcok]

Welcome aboard .
I suggest to read carefully this document about hum and noise .
http://www.jensen-transformers.com/an/an004.pdf
Ciao
Marco

 

[P.L.F.]

And one more clarification referring to the document Marco sent you:

[...]
NEVER, NEVER DEFEAT THE SAFETY GROUNDING of any device having a 3-prong power cord. The results of doing so can be deadly to you and/or your customer.
[...]

Correct by all means! The only reason I suggested experimenting the opposite is that in my country "ground" and "neutral" are always interconnected in line with the attached scheme (more details here: http://forums.phxaudiotape.com/show...ear-700-Series-II-White-Oak-Conversion/page46 , post 453). So my suggestions do not address defeating safety ground as such but grounding loops when present... Don't know the AC house wiring standard in Belgium though...

 

[Coldsmoke]

Thanks again to all of you guys,
Actually I think my cord is original, two prongs, no earthing of the cabinet...