404 owners

Soccerplyr · January 2003

I've had mine for 3 days now, and last night I noticed when it's not on it has a hum. Anyone else notice this?

TonyPTX · January 2003

Think I saw this in an earlier thread. If I remember right, someone called Polk up and asked them and they said it was OK for it to hum a bit. It's just the transformer for the amp anyway. If you really want it to stop, you can flip the auto switch to "OFF" and that should get it.

Soccerplyr · January 2003

only way I could get it to stop was to unplug it.

danger boy · January 2003

i was looking at this sub as a second one.. but it has a hum in it.. i don't want one now.

TonyPTX · January 2003

It's really not that bad...
Only way I can hear it is if I put my ear directly on the housing of the sub.

Soccerplyr · January 2003

I can hear mine from where I sit. Granted I was reading and nothing else was on. I like the sub, but my previous (velodyne) one didn't make a noise. tonight I'm going to plug it into a monster power center to see if maybe that will help, if not, I may return it.

danger boy · January 2003

it shouldn't hum if you are not using it. it should revert to stand by mode.. i think you may have a bum 404 sub.

TonyPTX · January 2003

The hum everyone is hearing is just the transformer that converts the power from 120V down to something the amp can use to drive the woofer. It doesn't make a difference if you plug it into a Monster Power conditioner or not. Power transformers hum....period! Put your hand on any of the big "power" blocks for the adapters to one of the accessories for your PC. Feel the vibration? That translates to a hum. The hum is not audible through the woofer or speakers. It's just the hum of a transformer. Next time you pass a high voltage power line, roll down your car window and tell me you don't hear a hum coming from the transformers (big cylindrical cans near the top of many posts.) I think the 404 is a fine product, it works well for me, and the hum is only noticible if you live in complete silence and are in the very near vicinity of the sub.

shiu · January 2003

I agree with Tony, the hum is from the transformer. The 202 has a small transformer and you could hardly hear such hum. I think the 404 is louder because of : a) it has a huge power supply transformer, in order to deliver 200 W average power. b) it probably use a transformer of lower quality than the one used in your Velodyne. A quieter transformer does not necessarily make better sound. I could hear the hum from up to 3 ft away, not bad.

RuSsMaN · January 2003

Ground loop anyone? This topic has been discussed at length many times, get your search on.

Cheers,
Russ

Soccerplyr · January 2003

Not a ground loop. Does it when it's plugged in and not connected to the receiver. My biggest concern is with the fact that it was not apparent from day one. I've got 30 days and it I decided I don't like it, I'll return it for something else.

I understand the concept of transformers and their hums. I'm just not to thrilled with the added noise. i can't say I've heard others complain about this with other subs, so I would call it a design flaw. I think polk could have done a better job in design.

Other then that I've been pretty happy with it's performance.

MxStYlEpOlKmAn · January 2003

Is it just me....or does all polk subwoofers have problems?
Hums...
Port Noise...
Bottuming Out...
Blown Drivers in the first week or so...
Not that Im an expert, But going back to the drawing board isnt a crime....

My M&K is huge all over, everything about it is big. The transformer, the amp, the drivers, the enclosure and so on. I hear absolutely NO HUM. So there is something Polk is doing wrong, what it may be, I dunno.

RuSsMaN · January 2003

Ground loop anyone? Cheater plug?

Cheers,
Russ

Yes, it could be the xformer, but there are other things to try before ditching the sub altogether.

Soccerplyr · January 2003

Russman-

What other things would you suggest trying?

In theory the monster sub cable grounds itself to the receiver when connected properly (Thats what the arrow on the cable is for), so I really doubt the problem is with ground loops.

I've now tried it with one of the 2 outlet monster power 2 converters and no change. I like the sub and really don't want to take it back. Plus it's much more astetically pleasing then the velodyne's

goingganzo · January 2003

i have olny had 1 sub and it has never humed it olny thumped but it is a velo. polk makes great speakers but i just dont care for their subs. i will take my velo over any polk sub. maby exep the 1200 and that is just a maybe. but i never had a velo cht15. now later in a few years when i decide to upgrade. i will be going with the ls line or their line like the ls line if they change it. i would have to say if this is a true problem polk maybe should re speck their sub amps with a better transformer.

shiu · January 2003

All transformers hum. I was thinking of returning mine too but I decided to keep it, after listening to several subs in the stores (Future shop) I bought it from. I put my ear onto (touching) the top and side of several subs on display, including Velodyne, JBL, and others. I found the 404's hum is about the same as the others, the PSW202 was actually much quieter. Typically, more expensive transformers are quieter, but the bottom line is, transformer cores are made of laminated steel, when subject to 60 hz current, the lamination vibrates and produce that humming noise. The lamination is necessary to reduce core loss. I think most people say their subs does not hum but I am not sure if they had tried putting their ear directly in contact with the cabinet, or whether their sub has a power switch. The Polk does not have a switch, so as soon as you plug it in, the transformer is energized. My receiver is like that too, and.........it hums just the same. If you have a ground loop it will hum much louder and you should be able to hear it from even 5 feet away.

danger boy · January 2003

ok, i'm convinced subs hum. I just came back from listening to my 350 and it does hum. ever so slightly. i had to put my ear right up to one of the ports to hear anything. when i move away 4 or 5 inches from the port. i can't hear anything anymore. very minor hum. that's within acceptable limits i think.. if your 404 is louder than that.. i'd be surprised.

shiu · January 2003

If you put your ear right up to (in contact with) the enclosure's side wall where the transformer is, you will hear a louder hum. If the noise is due to ground loop current, the hum would likely be louder, and would come from the loudspeaker itself. I still think that the 404 hums louder because its amplifier, at 200W average, requres a very large transformer, relative to its small enclosure. A 10" woofer Velodyne has a much larger box, but the transformer may be much smaller because the large box make it more efficient, hence no need for a large P/S transformer. This is just my educated guess.

404 owners

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