preenfm Forum

PreenFM => preenfm2 and preenfm3 => Topic started by: karlisss on February 10, 2021, 10:52:49 AM

Title: preen FM2 headphones 3.5 mod
Post by: karlisss on February 10, 2021, 10:52:49 AM

hallo
is there some schematic how to mod preenfm2 and make a audio headphones jack (like i can plug and listen headphones) directly from preenFM2 synth?

atm its only usable on desktop with audio interface who have L and R channel inputs.

maybe someode did it already?

Title: Re: preen FM2 headphones 3.5 mod
Post by: Xavier on February 10, 2021, 10:30:58 PM

Hi,

What version of the PCB do you have ?
Latest vesions allow you to plug a stereo jack in the audio output #2.
It also has a auxiliary output where you can add a headphone dedicated jack.

But in both case, no headphone emplifier, so the output level is not very high.

Title: Re: preen FM2 headphones 3.5 mod
Post by: karlisss on February 11, 2021, 10:15:55 AM

preenFM2 R5d

Title: Re: preen FM2 headphones 3.5 mod
Post by: Xavier on February 12, 2021, 07:42:05 AM

If you have stereo audio jacks on your preenfm2, you can wire the 2 jack pins like shown in green in the attached picture.
That will make audio Jack 2 to deliver a stereo signal when Jack1 is empty.
You can then plug a headphone directly.

Title: Re: preen FM2 headphones 3.5 mod
Post by: hitachii on February 18, 2021, 05:05:27 AM

If I'm using the R6, would it be the same configuration? I tried to do it based off of the picture twice and failed. No sound would come out of #1, and sound would still only come out of one side on #2.

Attached is the picture of the bridge I made (second time around, much sloppier than the first time but with the same results), as well as a clearer picture of the pins I chose. Figured that it would go in the opposite direction since the pins were upside down.

Title: Re: preen FM2 headphones 3.5 mod
Post by: Xavier on February 18, 2021, 08:55:36 AM

Quote from: hitachii on February 18, 2021, 05:05:27 AM

If I'm using the R6, would it be the same configuration?

Unfortunately it depends on the R6 version. R6.1 ? R6.2 ? R6.3 ?
R6.1 : The traces are different. There's nothing you can do. Sorry about that  :-\
R6.2 : Same audio wiring as R6.1 but you can use the Aux output as a secondary output and wire a jack there, after shorting the 3 "Aux" jumpers.
R6.3 : nothing to do, the stereo mode is already in place for the main jacks. (The secondary output "Aux" can also be used).

Title: Re: preen FM2 headphones 3.5 mod
Post by: hitachii on February 18, 2021, 09:15:44 AM

Luckily, I have the R6.2!

By shorting the jumpers, do you mean bridging the three tiny pads labeled "1", "2", and "Aux_5v" or something else? Sorry, I'm such a newbie   :D

Title: preen FM2 headphones 3.5 mod
Post by: Xavier on February 18, 2021, 09:22:57 AM

Quote from: hitachii on February 18, 2021, 09:15:44 AM

Luckily, I have the R6.2!
By shorting the jumpers, do you mean bridging the three tiny pads labeled "1", "2", and "Aux_5v" or something else? Sorry, I'm such a newbie   :D

Yes that' it  :) Be carefull they're tiny.

Technically, the Aux output is behind an op amp that i didn't want to wire by default.
Aux_5V will power the op amp.
"1" and "2" will feed it with the audio output.
then you can use the "Aux 1 2" 3 pins. The one below "Aux" is the ground, the 2 other ones are the audio outputs.
You can plug an headphone here, but keep in mind that there's no headset amplifier and the level will not be very high.

Title: Re: preen FM2 headphones 3.5 mod
Post by: hitachii on February 18, 2021, 09:39:30 AM

Thanks a ton, your instructions are loud and clear!