Residual white noise on DP24SD headphone output

[Mitch Gallant]

Phil .. yes one for each of L and R channel.
Thanks Arjan .. actually that Keen's box doesn't house that headphone noise-reduction adapter. Was used for another guitar/amp thing I built a few years ago and thought those mustard metal boxes looked neat so lol.

Keep in mind that the info above is suitable for phones with about 50 ohm impedance. You would need to adjust the resistor value if you use with phones with substantially higher or lower impedance. Pretty easy voltage divider math.

Also, I tried a 15 Ohm resistor which gives you about -9dB (about 1/3 voltage) drop in headphone output and there is still plenty of gain. Of course you are wasting a lot of playback signal power in the resistors (one for each channel) but 1/4W resistors are still fine for power dissipation.
My test gig with 15 ohm resistors is shown above.

p.s. .. to check for this "hiss" background noise, try this simple listening test:
In a quiet room, put your phones on and plug in. Without playing any tracks and with Stereo level at max and Monitor level at 12:00, listen to the difference between phones plugged and quickly removed. You should hear a faint hiss. On my system that level doesn't change even if the monitor level is turned up full (because that gain control is in the digital part of circuit).

 

[Arjan P]

@Mitch Gallant You might wanna downsize photos before you post them, it's my understanding the forum has limited bandwidth.. (and they load faster that way)

 

[Mitch Gallant]

Thanks Arjan .. done. Hopefully the updates propagate here.

 

[-mjk-]

Great idea Mitch. Don't you need 2 of these though - left & right signals?

The box solves another issue: 1 headphone jack.

I would also have put a couple of 3.5mm jacks there while I was at it.

 

[-mjk-]

In the future, please post external links to photos. We are trying to keep the operational overhead down (which is why the actual upload link was disabled). Thanks.

 

[Mitch Gallant]

hmm I was using the insert image URL and thought it was using the URL link in the message. Guess should use the link icon directly?

 

[-mjk-]

If it's a link to an off-site host, that's cool.

 

[Mitch Gallant]

I've updated the article to include more detail on the passive voltage divider idea and more accurate noise measurement results etc.
https://www.jensign.com/TascamRecorderNoise

 

[multiverse]

Good evening. New member here. I hope it's okay to bump an old thread. I found this thread searching Google for this exact problem. I just want to report that this headphone amp noise still has not been corrected as of early 2022 by firmware or hardware improvements.

I recently purchased and received today my Tascam DP-32SD 32-Track recorder, and tested it. One of the first things I noticed was that there was a fairly noticeable white noise in my headphones right as the machine booted up-- and the noise was not affected by anything such as fader levels, trim levels, monitor levels, the use (or non-use) of effects, etc. It's just a certain level of white noise that remains constantly on as long as the machine is on.

I find the noise to be distracting and annoying.

In order to compensate, I plan on raising the volume of the headphones so that I can hear what I'd consider to be the noise floor of any given recording. I wouldn't want to record a number of tracks and miss low-level sounds in the mix because they were buried under the white noise hiss, if that makes sense.

 

[Mark Richards]

Here's the result of real world measurements and conclusions from testing I did four years ago using my DP-24.

 

[dctdct]

Agree with all concluding: it is not in the record, it is just in the phone output circuitry. And annoying

I heard it from the beginning when I got my DP-24(MIDI). And I hear it constantly with my Sennheiser HD-600 during mute intervals of tracking or mixing. Annoying!

I just ordered an SPL control box for phones and speakers: Looking forward if I get the thing back quiet.

 

[dctdct]

How quiet it is now, with the SPL 2Control preamp between the Portastudio and headphones! Most of the hiss from the loudspeakers is gone too. Currently I made a straight connection without using the patchbay:
[DP-24] MONITOR OUT > TRS to XLR balanced > IN1 [2Control]
- for the loudspeakers [2Control] SP1 > XLR to RCA > IN [power amp] speaker A >
- for the headphones [2Control] "Phones 1" TRS front output

Will have to check the quality enhancement in the next couple of weeks more in depth. But the first hour of premixing and jamming with loudspeakers or with headphones was already a revelation in terms of clarity.

Eventually I will give it a try using DP-24 STEREO OUT (which should be even quieter than the MONITOR OUT) as well as connecting again through the patchbay, like all my other devices.

 

[shredd]

Stumbled on this thread when referenced in a different topic.
I'll agree with @Mitch Gallant - I'll hear hiss/white noise in my headphones when plugged directly into the DP-32 and the output is say 11 o'clock or more. Annoying, but has never shown up in my recordings. And my hearing is so bad, that I probably wouldn't notice.
That said - the previously-mentioned output/monitor controller providing the headphone and/or monitor feeds would surely do it. It's never bothered me enough to go that route (there's times where I listen/monitor via my mixing boards' headphone-out, and get less noise there).