Should I have resistors on my headphones out jack of my LM380 mini G. amp?

[Jasonmatthew911]

I've seen 47 - 100 ohm resistors going between the output of an LM380 - 2.5W amp and the tip and ring of the headphone output jack....I assume they are for impedance matching or attenuating the sound for headphones...Are they really necessary???...I ask because I would've liked to use the same jack for headphones with a speaker shunt, to power an external speaker cabinet if I wanted, without having to add another separate jack for the external speaker with speaker shunt, or an SPST switch to turn the speaker on/off...But then I figure, if I connect an unbalanced type 1/4" plug for a speaker, it will GND the Ring of the jack which carries the same signal as the Tip, and if they are connected together this will also GND my Tip with the main signal...Is there any type of capacitor or resistor that would allow me to connect between my Tip and ring of the output jack so that only the ring gets GND when I connect an unbalanced plug and not the Tip too, or is there just no way around this???...I want to send the same Mono signal to the tip and ring of output jack, but it would be nice if I could use the same output for my Headphones and for an external cab......Any help or ideas?

[Gurner]

If you a dealing with a mono signal - why mess about with a stereo 1/4" plug?

A tip & sleeve is all that's required - why the ring?

[Jasonmatthew911]

If you a dealing with a mono signal - why mess about with a stereo 1/4" plug?

A tip & sleeve is all that's required - why the ring?

I figured that I need the ring for the right side of the headphones, or else it will only sound on the left side, because a headphone jack has 3 contacts....How will both sides of the headphones have audio with a tip and sleeve only?...I know that I could do it if I connect my headphones to an adapter plug that will convert the headphone jack to Mono, but I wanted to be able to connect a TRS plug for headphones and a TS for external speaker use...I wanted to know if there is a way I can do both through the same jack, without having to have 2 separate jacks???

[Gurner]

My apologies....I was focusing on the speaker jack socket - which will be mono & therefore only need two connections....it's late here, drank too much beer too! (never a bad thing)

If you wanted to dedicate a pair of headphones to just this setup up, you could just short the two connections inside the headphone jack.....that way you could keep all your connections out of your amp pure mono (tip & sleeve) ...makes for a simple 'external connectivity' arrangment.

[Jasonmatthew911]

My apologies....I was focusing on the speaker jack socket - which will be mono & therefore only need two connections....it's late here, drank too much beer too! (never a bad thing)

If you wanted to dedicate a pair of headphones to just this setup up, you could just short the two connections inside the headphone jack.....that way you could keep all your connections out of your amp pure mono (tip & sleeve) ...makes for a simple 'external connectivity' arrangment.

Are you saying that I can use a TRS (w/ speaker shunt) jack and GND the ring and sleeve leaving only the tip signal?...Will doing this still make the Mono signal sound on both sides of the headphones???

[Gurner]

What I'm saying is if I wanted an amp where I could connect both mono headphones &/or a mono speaker .....I'd likely use a standard mono jack socket (tip & ground) ....that way all the actual 'external connectivity' needs no special handling.

Of course, you'll either need to short the tip to the ring in the headphone jack plug (hence me saying 'dedicate a pair of headpones to it), else a simple adapter cable to place between the amp socket & stereo headphones.

[Jasonmatthew911]

What I'm saying is if I wanted an amp where I could connect both mono headphones &/or a mono speaker .....I'd likely use a standard mono jack socket (tip & ground) ....that way all the actual 'external connectivity' needs no special handling.

Of course, you'll either need to short the tip to the ring in the headphone jack plug (hence me saying 'dedicate a pair of headpones to it), else a simple adapter cable to place between the amp socket & stereo headphones.

Yeah I know I could do it that way, but I would like it to sound on both sides with any pair of headphones without needing extra adapters, even if it's just a Mono signal anyways...I think I'll just dedicate a TS 1/4" with speaker shunt for the speaker output and a TRS w/ speaker shunt for the headphone output...Although, I'm still wondering if I need resistors on the headphone output, or can the LM380 drive most pairs of headphones alright???...I know headphones usually have a higher imedance than an 8 ohm speaker load....Does the higher impedance mean that the LM380 will push out less power or will the sound in the headphones sound saturated???...I'm not very good with this impedance matching stuff...Can you or anyone tell me what would work best or if leaving the resistors out is alright?