Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Completely noob question, how to measure DC offset - advice needed
New Posts  All Forums:Forum Nav:

Completely noob question, how to measure DC offset - advice needed

post #1 of 13
8/8/10 at 10:57am
Thread Starter 

Hi, i am about to buy a very nice marantz 2252b vintage reciver.

 

But after reading a lot about dc offset, it seems i cant buy a vintage equipment without having heard it or knowing the amount of dc offset.

 

So please explain to me, how do i measure dc offset (in a newbish way, preferably)

 

What do i connect to what (this is the part im most confused about)

 

But also please explain all the others details to me one more time

 

Thanks

 

Rune

Reply
post #2 of 13
8/8/10 at 11:13am

Well, do you have a Voltmeter with DC-mode?

If so, that would be a good starting point!

Reply
post #3 of 13
8/8/10 at 11:14am

Measure DC voltage on the output.

Reply
post #4 of 13
8/8/10 at 11:17am

I guess that´s not the kind of answer the TO wanted?

Reply
post #5 of 13
8/8/10 at 12:21pm

yep, if you have a meter, measure DC voltage across left/ground and right/ground

Reply
post #6 of 13
8/8/10 at 9:51pm
Thread Starter 

The person who i would buy the amp from has a meter, but i cant recall having a meter in my own hands. So how do i explain to him, without knowing what im saying, what he needs to do?

 

Sorry for my stupid questions, but you guys are my only solution

Reply
post #7 of 13
8/8/10 at 10:17pm

If he has a multimeter, he'll know what you mean when you ask "What is the DC offset" or "What is the DC output level".  If not, ask him to measure DC volts (hopefully millivolts) of the outputs (left output to ground and right output to ground, measured from the inside of the RCA connector to the outside of the RCA connector).

Reply
post #8 of 13
8/8/10 at 11:45pm

The preamp outputs are internally switched on the 2252B, attempting to measure the DC offset at the RCA jacks (with just the meter probes) will not give you accurate results. ;)


Edited by MisterX - 8/9/10 at 12:15am
Reply
post #9 of 13
8/9/10 at 2:03am

 

 

1. Speakers disconnected (or connect the meter to the 'B' speakers and set the front panel speaker control accordingly)
2. Input set to an unused position (not Phono)
3. Volume control at minimum.
4. Balance in center
5. Tone controls either defeated or set to mid position
6. Set your meter to read DC, and set to a low scale (300mV scale is common) Connect directly to the Pos and Neg of the speaker terminals
7. Give the amp 10 minutes to settle.

Reply
post #10 of 13
8/9/10 at 2:08am
Thread Starter 
Quote:
Originally Posted by MisterX View Post

The preamp outputs are internally switched on the 2252B, attempting to measure the DC offset at the RCA jacks (with just the meter probes) will not give you accurate results. ;)


What do i do then?

Reply
post #11 of 13
8/9/10 at 3:38am

Ask the seller to take it to qualified technician for evaluation and provide a copy of the invoice.

It's not your responsibility to make sure it works properly.

Reply
post #12 of 13
8/10/10 at 12:46pm
Thread Starter 

Thanks for the help, it seems he measured the reciver to 153mw right and 149left, so you guys just saved me from a bunch of crap.

 

Thanks a lot!

Reply
post #13 of 13
8/10/10 at 5:19pm

 

 

Do you mean 153mv,that is a lot,makes me wonder how it was measured.

Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Completely noob question, how to measure DC offset - advice needed