Speaker Protection Board Question (WOPL 400)

[mjstriker]

Been out of town for almost 2 months with work so the phase linear hasn't been getting much use. Last few days been playing it almost 24/7. Picked up some nice Polk monitor 10b's for cheap and recapped them. They guy selling them was trying to sell me his "higher end" models not knowing the Polks were hands down the best of the group. They are a great speaker and work well with the WOPL 500 pumping out some tunes. After caps break in will look to refinishing the veneer and they will probably serve main duties in the living room.

Anyways to the question at hand. Recently noticed I get a small speaker crackle when I unplug the amp. Was wondering if maybe the protection board is having some issues? Like the relay isn't engaging soon enough and I am getting a slight discharge which is audible prior to the relay kicking in to kill any current.

I have recently switched my set up around adding a DAC to the loop. Dont' know if I could be having issues with power conditioning. I do have a slight hum which I think is some sort of ground loop that I am trying to narrow down

 

[laatsch55]

At power off the relays goes as soon as power is removed, I have yet to see that phenomenon yet..do you have a cable box in the house?

 

[mjstriker]

I do. Didn't have the issue when hooked up in the garage so was thinking it might be an
external power issue. Will have to unplug a few things and see.

 

[mjstriker]

Tried unplugging various things in the house and still get the slight crackle on turn off. Noticed I have a hum in both speakers that worsens when I turn the volume up. I am thinking I may have a ground problem somewhere. Decided to move the unit into the garage to open it up. At that point I hooked up some cheap-o speakers and turned it on with no input. I am getting a nice loud hum through the left speaker. Checked the frequency and it is right at 180 hz. Looks like the 400 is sick. Gonna open her up and see if I can narrow down where the frequency is originating.

Also in general I feel the noise floor isn't that quiet on the unit especially when reading other posts about how dead quiet there's are (I feel my Citation 16 is more quiet). Is there some wiring pathways or general things I can look at to ensure I am getting the least amount of noise? Thanks

 

[laatsch55]

If there is no input to the amp and there are no shorting plugs in the RCA's it's going to be VERY NOISY...

 

[mjstriker]

If there is no input to the amp and there are no shorting plugs in the RCA's it's going to be VERY NOISY...

Well that answers that. Was thinking something was totally botched for a second there.

Have any suggestions on what I can look into to lower the noise floor? Thanks

 

[laatsch55]

Build some shorting plugs to see just how much noise is attributable to the amp alone. Review Joes grounding scheme in the WOPL archives . Post about what you don't understand..

 

[mjstriker]

Build some shorting plugs to see just how much noise is attributable to the amp alone. Review Joes grounding scheme in the WOPL archives . Post about what you don't understand..

Thanks for pointing out the post. Exactly what I was looking for as a starting point

 

[Northwinds]

I blew up a pair of Polk Monitor 10A's quite easily with the WOPL500. The fuses on the speaker backs were popping so I upped them to 3.5A fastblo's and they did not blow fast enough, took the dual drivers right out on both speakers. If you need the crossovers, I can hook you up for your 10B's if you hurt yours. I like the fact you have fuse protection at the terminals even though I violated their rating LMAO. I also have a set of Peerless gold back tweeters that are a nice swap for the SL-2000's. Magnets are slightly larger so the hole needs to be opened up a hair

 

[mjstriker]

I blew up a pair of Polk Monitor 10A's quite easily with the WOPL500. The fuses on the speaker backs were popping so I upped them to 3.5A fastblo's and they did not blow fast enough, took the dual drivers right out on both speakers. If you need the crossovers, I can hook you up for your 10B's if you hurt yours. I like the fact you have fuse protection at the terminals even though I violated their rating LMAO. I also have a set of Peerless gold back tweeters that are a nice swap for the SL-2000's. Magnets are slightly larger so the hole needs to be opened up a hair

WOPL 500 does pack some juice and gets the drivers going for sure!! Thanks for the generous offer but I Just re-capped the crossovers on each speaker and replaced the resistors. The 10b's I have do not have actual fuses only a polyswitch to protect the tweeter. I ended up taking those out and just replaced with a resistor. Some say the sound is better and I figured if I blew the tweeters I could always upgrade to the Peerless like you have.

How do you like the Peerless? I kind of enjoy the high end but it can get a little pitchy so I might try the Peerless one day.

 

[Northwinds]

The Peerless came out of Cizek Monitors. They are highly regarded I guess

 

[eminence1963]

The Peerless came out of Cizek Monitors. They are highly regarded I guess

They are all the rave according to people on the Polk Forums. Which BTW has been down for quite some time now. Can anyone confirm this for sure?

 

[mjstriker]

So I have narrowed down the hum in the right channel to the faceplate. After looking over all my ground points and scratching my head I realized the hum goes completely away with the faceplate off and lying in front. As I slowly raise the faceplate to its proper position the hum is re-introduced. With it down the noise floor is dead quiet. Trying to narrow down what component/wire is the culprit.

On a side note installed the new light assembly with the blue LED's. Pretty sweet!!

 

[laatsch55]

Take a jumper wire and go from the faceplate to the chassis with the faceplate layed down. If you have hum then, play around with the AC wires going to the switch. It souinds like you have the AC running to close to the pots.....is this a 400?? With no pots??

 

[mjstriker]

400 without switch or pots

 

[laatsch55]

Transformer bolts tight?

 

[mjstriker]

They are tight. Pretty sure I found the interference. The jumper did not introduce the hum but I slowly pushed the bundle of wires (the culprit most likely being the two AC wires) going to the faceplate and as they came closer to driver board the hum appeared. Looks like I need to devise a better way to route the wires to the faceplate preventing them from getting close to the board

 

[laatsch55]

Are they trying to lay on top of the driver board?

 

[mjstriker]

Pretty much. They are solid core so I think I can adjust them to run straight up the back of the faceplate and over to top part of chassis away from the driver board

 

[laatsch55]

The top of electrolytic caps are conductive, if you have an AC wire laying on one it could do it...