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SEQUENTIAL/DSI => Prophet => Prophet Rev2 => Topic started by: alexandreleblanc on June 09, 2018, 02:37:58 PM

Title: My Rev2 is noisy
Post by: alexandreleblanc on June 09, 2018, 02:37:58 PM
Hello Guys,
I have plugged my Rev2 outs with 1/4" mono (unbalanced) Jacks (digiflex cables) directly to my Audient ID22 Soundcard.

The noise floor seems to be very high. So when i boost the highs with an Eq or if i compress the sound i get with a really noisy signal.

Do you have any idea how can i improve this ?

I also have a DSI Tetra that is way less noisy than my Rev2.

 ???
Title: Re: My Rev2 is noisy
Post by: Chimponaut on June 09, 2018, 02:53:08 PM
Do the inputs you are using have a Mic/Line switch somewhere by any chance? Maybe a -10 / +4 switch? Shouldn't be noisy. My Rev 2 noise floor settles right around -80db when I'm tracking and getting levels of around -18db or -12db.
Title: Re: My Rev2 is noisy
Post by: alexandreleblanc on June 09, 2018, 02:53:46 PM
Here's a screen shot of what looks like when there's no sound playing on the Rev2 recording channel.

You can see the noise very high
Title: Re: My Rev2 is noisy
Post by: alexandreleblanc on June 09, 2018, 03:00:34 PM
Do the inputs you are using have a Mic/Line switch somewhere by any chance? Maybe a -10 / +4 switch? Shouldn't be noisy. My Rev 2 noise floor settles right around -80db when I'm tracking and getting levels of around -18db or -12db.

No, my sound card dosen't have a switch. It's a Audient ID22.
Title: Re: My Rev2 is noisy
Post by: Frocktar on June 09, 2018, 06:20:47 PM
That image doesn’t look right that’s for sure.

Assuming you have run the calibration?

If so I’d contact support too as well as this forum.

Good luck, hope it’s something simple.
Title: Re: My Rev2 is noisy
Post by: Chimponaut on June 10, 2018, 01:23:00 AM
Quote
No, my sound card dosen't have a switch. It's a Audient ID22.

Good for you, I have the ASP-880. The ID22 does have a Mic/Line switch. RTFM!
Title: Re: My Rev2 is noisy
Post by: alexandreleblanc on June 19, 2018, 06:51:04 AM
Quote
No, my sound card dosen't have a switch. It's a Audient ID22.

Good for you, I have the ASP-880. The ID22 does have a Mic/Line switch. RTFM!

Sorry but the ID22 is not equipped of a mic/line switch. I have read the manual and test all what i was able to test before posting my question on this forum.


Whether I plug the Rev2 into the Mic / Line input of the ID22/ASP880 or plug into the D.I inputs, it does not make any difference to the noise level.

The audio signal comming from the Rev2 is still noisy.
Title: Re: My Rev2 is noisy
Post by: AlainHubert on June 19, 2018, 07:43:31 AM
Quote
No, my sound card dosen't have a switch. It's a Audient ID22.

Good for you, I have the ASP-880. The ID22 does have a Mic/Line switch. RTFM!

Sorry but the ID22 is not equipped of a mic/line switch. I have read the manual and test all what i was able to test before posting my question on this forum.


Whether I plug the Rev2 into the Mic / Line input of the ID22/ASP880 or plug into the D.I inputs, it does not make any difference to the noise level.

The audio signal comming from the Rev2 is still noisy.

From page 12 of the ID22 user manual (pdf version):

"Plugging in a TS (tip-sleeve unbalanced)
jack will override the mic signal and turn
channel two into a fully fledged, fantastic
sounding instrument input with access to a
-10 dB pad (for hot output instruments such
as active basses, drum machines and
synthesizers), polarity reverse (useful for
phase alignment between a mic and D.I) and
the HPF (useful for taming unruly low
frequency content)."

Title: Re: My Rev2 is noisy
Post by: alexandreleblanc on June 19, 2018, 07:56:38 AM
Quote
No, my sound card dosen't have a switch. It's a Audient ID22.

Good for you, I have the ASP-880. The ID22 does have a Mic/Line switch. RTFM!

Sorry but the ID22 is not equipped of a mic/line switch. I have read the manual and test all what i was able to test before posting my question on this forum.


Whether I plug the Rev2 into the Mic / Line input of the ID22/ASP880 or plug into the D.I inputs, it does not make any difference to the noise level.

The audio signal comming from the Rev2 is still noisy.

From page 12 of the ID22 user manual (pdf version):

"Plugging in a TS (tip-sleeve unbalanced)
jack will override the mic signal and turn
channel two into a fully fledged, fantastic
sounding instrument input with access to a
-10 dB pad (for hot output instruments such
as active basses, drum machines and
synthesizers), polarity reverse (useful for
phase alignment between a mic and D.I) and
the HPF (useful for taming unruly low
frequency content)."

This is exactly how my Rev2 is plugged into my sound card.

Connected with a 6' Digiflex TS 1/4" jack to the Mic / Line input. So the input of my soundcard is switch to line level mode.

I have tried the line input and the D.I input but this dosent change anything to my problem.

I also tried with other cables, and also TRS jacks but i always got the same result.

P.S. note that my Synth IEC is also plugged in a Furman PL-8C power conditionner. So i don't think that the noise is caused by a bad electrical supply.
Title: Re: My Rev2 is noisy
Post by: AlainHubert on June 19, 2018, 09:11:33 AM
I get about the same results as Chimponaut (around -80 db noise floor on the REV2).

So yes, the REV2 is very slightly noisy. But when you consider that it is an analog polyphonic synth offering 16 analog voices, it's bound to be a little noisier than a 4 voices only Tetra. 

But if you feel that it's abnormaly high, you could always contact DSI support and see what they say about it ? But I suspect that they'll probably tell you that it's perfectly normal for such a device.
Title: Re: My Rev2 is noisy
Post by: alexandreleblanc on June 19, 2018, 09:49:16 AM
I get about the same results as Chimponaut (around -80 db noise floor on the REV2).

So yes, the REV2 is very slightly noisy. But when you consider that it is an analog polyphonic synth offering 16 analog voices, it's bound to be a little noisier than a 4 voices only Tetra. 

But if you feel that it's abnormaly high, you could always contact DSI support and see what they say about it ? But I suspect that they'll probably tell you that it's perfectly normal for such a device.

Thank you Alain! This answers my original question. I also have about -80 db of noise.
I was wondering because I also have a Tetra and I notice that the noise floor is lower on this device. I am used to digital synthesizers, so this is the first time I see a level of noise like this.

I understand now with your answer that this level seems normal for Rev2.
So I'm going to live with that.

Do you think that the number of oscillators or voices for this synthesizer has an impact on the noise level?

More oscillators = more noise?
Title: Re: My Rev2 is noisy
Post by: AlainHubert on June 19, 2018, 10:22:53 AM

Do you think that the number of oscillators or voices for this synthesizer has an impact on the noise level?

More oscillators = more noise?

Obviously. In the analog world, more sound sources always equals a little more noise. Unless some compander gimmicks are used, which always impact the sound to a certain extent.

But, to be fair, a -80 db noise floor is pretty low considering that there are 32 op amps for a stereo 16 voices analog synth. And I'm sure that if you raise the monitoring volume level high enough in order to actually hear that noise floor in your headphones, and accidentally hit a note on the keyboard, you'll probably have ringing in your ears for a few minutes after that !  :o
(don't do it)
Title: Re: My Rev2 is noisy
Post by: discorules on June 20, 2018, 02:34:15 PM
I've noticed that some of my equipment (not only the Rev2 but an Octatrack / Rytm) gets REALLY noisy if i plug it on the USB port. As soon as i unplug the USB, the noise go away. Maybe you should give it a try, if you are using USB to plug the Rev2 into the computer.
Title: Re: My Rev2 is noisy
Post by: Robot Heart on June 20, 2018, 04:51:32 PM
Hi discorules-

This sounds like a ground loop. Here's the info we recommend to our customers:

Try changing your plug configurations for the synth and your laptop, i.e. try unplugging your laptop from the wall and see if the problem still exists, and try plugging your DSI synth and the computer into the same outlet. You can also try using a surge protector/power conditioner, try powering your audio interface with a wall plug if it is bus powered normally, try plugging your DSI synth into a different USB port, use a different or shielded USB cable, or try a USB hub if you haven't already.

If none of the above suggestions work, users have had good results using the following DIY method. You must have an extra USB cable you don't mind modifying:

```
* Using wire strippers and/or wire cutters, Strip away a 10-15mm section of the rubber coating in the middle of the USB cable to expose the braided shielding.
* With the wire cutters, carefully cut the shielding away entirely, exposing the 4 wires surrounded by the shield.
* Make sure the shield is completely disconnected. Verify this by testing for continuity on both metal ends of the cable.
* Cut the black wire, which is connected to pin #4 and represents ground. This creates a "ground-lift".
* Fold the ground wire back and out of the way, then wrap the exposed section of the USB cable with electrical tape. Your ground noise should be gone.

```

If you'd rather not try a DIY fix, some companies also make USB signal isolators. Here are some examples:

**USA:** USB signal isolator (http://microcontrollershop.com/product_info.php?currency=USD&products_id=3769)

**EU:**  USB signal isolator (http://electronics-shop.dk/isolated_serial.htm?currency=EUR)


You can read more about locating and eliminating ground loops in your system at the following web link (PDF file):

Understanding & Eliminating Ground Loops (http://www.davesmithinstruments.com/wp-content/uploads/2015/03/Understanding-and-Eliminating-Ground-Loops.pdf)
Title: Re: My Rev2 is noisy
Post by: musicsound on June 22, 2018, 03:15:43 AM
my too. Bought is yesterday
Title: Re: My Rev2 is noisy
Post by: RonGerrist on June 22, 2018, 08:46:14 AM
What about just using a MIDI interface? Would that solve the problem? You can get this for very cheap to give it a shot.
Title: Re: My Rev2 is noisy
Post by: aaronsimsg on August 15, 2018, 08:10:37 AM
I did a check and found mine has a -65db noise floor, is that acceptable?
It's my first analog synth and I'm trying to learn what to lookout for.
My Minitaur that was ordered together has only -85 to -80db.
Title: Re: My Rev2 is noisy
Post by: guyaguy on August 17, 2018, 05:34:01 PM
-65db is in the acceptable range.
Title: Re: My Rev2 is noisy
Post by: aaronsimsg on August 18, 2018, 04:17:58 AM
-65db is in the acceptable range.

cheers thank you
Title: Re: My Rev2 is noisy
Post by: Nsemest182 on August 29, 2018, 07:41:12 AM
I had the same issue. I went from the TRS Main (A) outs to a Radial DI box, pushed in the Ground/Lift button and the issue went away.
Title: Re: My Rev2 is noisy
Post by: discorules on July 14, 2019, 04:22:35 PM
You can read more about locating and eliminating ground loops in your system at the following web link (PDF file):

Understanding & Eliminating Ground Loops (http://www.davesmithinstruments.com/wp-content/uploads/2015/03/Understanding-and-Eliminating-Ground-Loops.pdf)

Thank you very much for such a detailed answer, will check here.

Cheers !
Title: Re: My Rev2 is noisy
Post by: seq_user12123 on July 16, 2021, 12:09:38 AM
i had the same or at least a similar problem. Regardless of the master volume output, I always had a kind of background noise on all outputs, i.e. headphones and line outs even if the master volume output was "0". In addition, there was a signal in the high frequency range that was only visible after I played a sound.

i have attached the frequency spectrum of the broken device and a small video that shows what was happening after I had played any sound. But regardless of what the frequency spectrum showed, the background noise could always be heard.

I tried to re-import the firmware, to reset the device and to recalibrate it. unfortunately nothing helped.

Solution: i had to exchange the device. and now everything is fine. no more rushing at all and no strange signals in the frequency spectrum either. now the rev2 sounds perfect and 100% clean.