• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Using a stereo 3.5 mm audio jack connected to a mono speaker: Out Of Phase Stereo (OOPS)

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia
I just couldn't find any info anywhere on using Apple USB-C Headphone Adapters with a 3.5 mm audio jack connected to a speaker. I know this is due to the sheer simplicity of it.

But I have questions!

1. Mine are mono only (3.5 mm to two wires, red and white), but when you input 3.5 mm stereo to a mono speaker, certain popular music have the vocals etc cancelled out (like the karaoke function in some editors) so the background music comes out very clear. I have a direct 3.5 mm to 2 ch speaker system which used to be connected to the Logitech subwoofer. That stereo speaker system works fine. Stereo to a mono is not straightforward. The bass speaker from Logitech is like a low pass filter. Other sources distort badly. There is a lack of clarity in the sound in some complex tracks. Or nothing is heard at all. Why does this happen? Or is this simply the speaker's frequency response?

2. My 4 ohm sony speaker distorts when used with apple dongle on higher volume. But the 8 ohm tv speaker works very well. Would a dongle with 2VRMS avoid this distortion?

I was always amazed to see how nearly nothing can be heard on speakers from a Realtek chip via 3.5 mm, but Apple dongle can drive it plenty loud.
 

Zek

Major Contributor
Joined
Feb 17, 2018
Messages
1,582
Likes
2,146
Are you talking about passive or active speakers?
No one USB dongle is designed to drive passive speakers, but headphones or active speakers.
 
OP
Saidera

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia
These speakers are all passive and taken out of their enclosures. I agree that this is not the usual way of using USB dongles.
 

KeithPhantom

Addicted to Fun and Learning
Forum Donor
Joined
May 8, 2020
Messages
641
Likes
658
These speakers are all passive and taken out of their enclosures. I agree that this is not the usual way of using USB dongles.
If you are using these dongles as amps for passive speakers, they may be running out of juice. At least I would use small integrated amplifiers or small amplifies for speakers.
 
OP
Saidera

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia
Thanks for the replies!

No, Apple USB-C is sufficiently powerful.

It's just DIY bare speakers from cars, TVs, 5.1 ch systems...connected to a stereo 3.5 mm cable and powered by stereo signal>mono speaker
 
OP
Saidera

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia
OP
Saidera

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia

Bamboszek

Active Member
Joined
Mar 17, 2018
Messages
181
Likes
306
If I understand correctly you are shorting both channels and driving 4 ohm load with USB dongle.
Even if dongles IC include some kind of protection, that's definitely running out of specification and dongle would be probably damaged sooner or later.
If you want experiment like this at least connect two 8Ω drivers in series to get more reasonable 16Ω load. And don't short stereo channels to mono.
 
OP
Saidera

Saidera

Senior Member
Joined
Jul 18, 2020
Messages
388
Likes
309
Location
Adelaide, South Australia, Australia
If I understand correctly you are shorting both channels and driving 4 ohm load with USB dongle.
Even if dongles IC include some kind of protection, that's definitely running out of specification and dongle would be probably damaged sooner or later.
If you want experiment like this at least connect two 8Ω drivers in series to get more reasonable 16Ω load. And don't short stereo channels to mono.
So there is a short? How does the OOPS effect relate to that? If my jack was mono, I guess it would not have the OOPS. It is a problem arising due to only two wires and a ground wire attached to the jack. If it had four wires, I'd have stereo. Apple provides a warranty, and I don't think connecting a mono speaker to the dongle is misuse or abuse of the dongle. I'll report here if it gets damaged...
 
Top Bottom