How much DC is considered safe?

If you measure the DC voltage at the amp's speaker output terminals, how much DC is considered safe? I have a pair of monoblocks that I measured a maximum of -32mV on one amp, dropping to about -21mV on the other. Will this small amount of DC cause any harm to the speakers?
An 8 ohm speaker with 32mV across it would dissipate 128 microwatts or .000128 watts. I think you are safe.
In short-0
But-My understanding is that measuring dc with ac present usually results in unreliable readings. Especially true with most garden variety digital meters. Probably not to worry over those readings. Tweeters generally safe from low amounts because of the caps. Do you hear any pops from the woofs when you fire them up?

There are more tech oriented forums than here. As a failsafe try asking your Q at the Asylums DIY page or bottlehead.

The world ain't right when Plato is taken rif from Clueless.
Great parting comment, Clueless :^)! Anyone here monikered Aristotle??? Cheers.
Thanks guys. I think I'm fairly safe at the level of DC the amps exhibit, but was just wondering at what DC voltage threshold would one need to be concerned?

If anyone here can answer that, by all means do so, otherwise I may do as Mr. Clueless suggests and pose my question in a more technical forum. BTW, that parting comment should have read, "takin' riff" not "taken rif." ;P

Don't take these figures as "gospel" (there are far too many variables out there) but figures around and under 20mV are fairly innocuous, figures from 20 to 50mV should probably be adjusted out and figures above 50mV can often be classed as a fault condition. Hope this helps.

Regards, Richard

Fuley apreciate da Engleash Leson. Duh..., youve redemed youself as intelagent as fer as me are cuncrned.

As soon as i saw it posted I shook my head. Have you ever noticed how careless e-mail makes you? Maybe it is just me.I have an immediate liking of anyone named Plato as I live in a cave and spend lots of time looking at the shadows on the walls. Have you ever noticed how poor the sonic qualities of rock is.

Anyway. I still think you want 0 (or very close) dc and your reading is not reliable. I am not an amp person (i do like to make speakers) but i assume the real issue is sound. dc running out is not going to help the coil make sense of what it is trying to do and well... all the cable up grades in the world will not help. A well designed pre/amp should block the dc and it becomes an issue long before you have to worry about the health and welfare of your speakers if you want music.

Do me a favor, if you find an answer post it back here. It would be appreciated. Maybe we can publish a dialogue about it.

Sincerely, I remain

Thanks for that bit of knowledge; it makes sense to me. I remeasured the amps today after playing around with them a bit and now they both measure under 20mV. So it would appear that they will be safe enough to use. I will be in touch with the amp's designer next week when he returns from CES, and perhaps he will have more to say on the subject. Prior to my posting this question, he sent me a message not to connect my speakers to the amps if I measured more than 20mV of DC offset following a 10-minute warm-up period.

Dear Clueless, your sense of humor is appreciated and no offense is taken. I think that DC offset in small amounts will pull or push your speaker's diaphram/cone out of its neutral resting position, although that may not be audible in most cases, which is why you need to measure for it. Of course larger amounts of DC can act to destroy drivers. My measurements were taken at the amp's speaker posts while the speaker cables and interconnects were disconnected.

Have a great weekend guys!
see what happens when the amp inputs are shorted, this info might tell the manufacturer something useful when you talk to them. If you're not applying any signal (playing music) then there's no AC component to confuse the meter when you take this meassurement, which you do appear to be doing correctly. Any offset values >100mVDC I would really start being concerned, & the amp may even go into DC protect mode around that point.

I tried your suggestion about using the input shorting plugs and retaking the measurements. Curiously, with the shorting plugs both amps measured 4 to 5 mV higher DC than without the plugs. I don't know why that should be, but it's what I got.