Author Topic: Volume control instability  (Read 1835 times)

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Offline MrRich

Volume control instability
« on: February 20, 2021, 08:36:01 PM »
Issue: static and volume instability.

I decided to purchase a pair of new PreSonus, ErisE8, powered studio monitors for my Tyros 5. I wired the monitors directly to the keyboard R & L outputs using balanced cables with XLR plugs at the monitor ends and balanced 1/4" plugs at the keyboard. At the time I did not realize that the Tyros 5 keyboard 1/4" outputs are NOT balanced. As soon as I started playing the above "issues" appeared. The volume of the keyboard will go up and down at random, the channels emit static at random, and the sound images become distorted at any listening level above 1/2.

As an experiment I wired the monitors to the keyboard using unbalanced cable with standard 1/4" stereo plugs on both ends and the issues have seemed to disappear.

Has anyone else had this happen when connecting monitors with balanced cables? I can understand getting some static...or distortion...but what about the volume going up and down on it's own? Can anyone possibly explain that?

Some research I did indicates that I will need to install a passive DI box if I want to convert the unbalanced signals at the keyboard to balanced signals to the monitors. This will be necessary if I want to use my subwoofer which only has balanced xlr in and out ports for use with powered monitors. Is this what others have done to get around the Tyros 5 not having balanced plugs for signal output?

Thanks all for any information to help me further understand this balanced/unbalanced mystery.

Offline MrRich

Re: Volume control still unstable.
« Reply #1 on: March 11, 2021, 01:09:37 PM »
Well....I thought the unstable volume control issue went away, but it didn't. Now when I play the volume will increase or decrease at will. In other words, if I set the volume knob at 50%, the volume might spontaneously drop down to as low as 10% or go as high as 90%....without ever touching the control knob. This wacky, uncontrolled volume just happens at random sometimes remaining stable for an hour or so before acting up. It is driving me crazy! Yes the issue has been isolated to the keyboard through the process of elimination. Any help is appreciated. Rich

Offline overover

Re: Volume control instability
« Reply #2 on: March 11, 2021, 02:50:07 PM »
Hi Rich,

in my opinion, the problem described (volume "instability") cannot have anything to do with the fact that you initially used balanced cables.

As you have correctly stated, the output jacks of the T5 are unbalanced. If you use a balanced (TRS) jack plug, the middle contact (Ring) does not receive a signal because the Ring contact is not connected inside the T5 output sockets. A balanced input on an active speaker or mixer then only receives "half" the signal (only the plus-phase on XLR pin 2). This basically leads to a much quieter signal (-6dB) and can also lead to hum, as the input for the minus-phase (XLR pin 3 = Ring contact of the TRS plug) is OPEN.

By the way, you don't necessarily have to use DI boxes to connect the T5 to balanced inputs. If you are using relatively short cables (maximum 3 - 5 meters) it is usually sufficient to work with unbalanced cables. To do this, the XLR pins 1 (ground/shielding) and 3 (minus-phase) simply have to be bridged. This can be done either in the XLR plug or in the jack plug. When using a TRS plug, it is sufficient to connect the Ring contact to ground/shield contact and the cable is unbalanced. :)

In addition, unbalanced cables should not be laid parallel to mains cables, if possible, in order to avoid hum interference. And to avoid hum caused by potential differences, the keyboard and speakers / mixer should be connected to the same power strip.

First I recommend using the AUX OUT sockets as a test (instead of the Line Out Main sockets). The AUX OUT sockets have a fixed volume, so they are not controlled via the Master Volume dial. Please make sure beforehand that "AUX OUT" is activated in the Mixing Console > tab "Line Out" (not "Sub 3-4).

If the volume remains stable when using the AUX OUT sockets, there is probably a hardware problem (e.g. on the Master Volume potentiometer or in the signal path of the Line Out main sockets, or maybe a loose contact (bad solder joint) on the Line Out Main sockets).

Another way to isolate the problem would be to test whether the volume at the headphone socket fluctuates at the same time as the volume at the Line Out Main sockets: If not, it is probably NOT due to the Master Volume potentiometer.

If the "volume instability" occurs when playing with STYLES, it could be due to the following setting:

Please make sure that in the Style Setting display ("FUNCTION> STYLE SETTING / SPLIT POINT / CHORD FINGERING> tab STYLE SETTING") the parameter "STYLE TOUCH" is set to Off. (When this is set to "ON," the Style volume changes in response to your playing strength in the chord section of the keyboard.)

Please also make sure that the current firmware is installed on the T5 (V1.13). This ensures that the Sliders are correctly calibrated (so that the values of the assigned parameters do not change "by themselves").

If you have connected a Volume Pedal (FC7) to one of the Pedal sockets of the T5, I recommend configuring it so that only the RIGHT parts are controlled in terms of volume (not the entire keyboard).

Please also check the assignment of the "Assignable Slider": Press "[Direct Access] and then move the Assignable Slider slightly. If "Keyboard Volume" is assigned here, there is a risk of accidentally changing / limiting the volume of the Keyboard parts. If not required, I therefore recommend setting this Slider to "Off".

Hope this helps!

Best regards,
« Last Edit: March 11, 2021, 02:59:39 PM by overover »
Everyone always said: "This is not possible!" - Then someone came and ... just did it!

Offline MrRich

Re: Volume control instability
« Reply #3 on: March 19, 2021, 06:12:04 PM »
Hi Chris,

First, I very much appreciate you taking the time to reply and offer these great suggestions so I could try to isolate this issue. Thank-you!

This is what I have done so far:

With two pair of powered monitors (JBL 8" and Presonus 8") I have alternatively plugged these into both the T5 main r & l outs, and the aux 1 & 2 outs (with monitor gain controls used to set the listening level). I did this using 1/4" to 1/4" cables then 1/4" to XLR cables (with a DI unit) in every possible configuration. The volume issue persisted. Also, no hum was noted at any time. My keyboard is plugged into an AC-outlet separate from that of the monitors. I found that if I power them all up together I would sometimes get a single snap/crackle thru the monitors. Powering up the monitors and the keyboard with a slight delay between them, eliminates this.

Next, listening thru the headphones...the problem remains.

Checking the style-touch was set to "off".

Checking the displays V1.13.

No pedals are currently plugged into the keyboard.

The slider is being used to control multi-pad volume.

Chris, taking the time to go thru the checks you recommended has allowed me to hear if there is any pattern to this problem. I've discovered that this issue has no pattern and that the volume can change level at any time. I've even tried shaking the keyboard to see if the volume changes when I do that. It doesn't. I was also hoping the problem would get worse over time to make it easier to diagnose. It hasn't. This week I played this keyboard for two days (5-6 hrs total) and the volume did not fluctuate at all. This morning however was a different story. 10 minutes after turning on the keyboard the volume jumped up 40-50% and stayed there for nearly 1/2 hr before suddenly dropping back down. BTW the temp in this room is maintained at 68-69*F.

I am thinking now that this problem is somewhere hidden in the circuitry of the keyboard. Do you know if there is an isolated board in the T2 which has to do with volume control or do you think this is going to be a witch hunt? I am not hesitant about a qualified technician taking a look....what I am concerned about is that both of the Yamaha certified repair centers near me currently have 4-5 week backlogs for service. Then if parts have to be ordered that's another week or two. I don't even want to think about my keyboard being kicked around a repair shop for two months before I get it back.....ugh! 

Chris....thanks again!


Offline EileenL

Re: Volume control instability
« Reply #4 on: March 22, 2021, 02:09:02 PM »
Dose your keyboard work fine on the Yamaha speakers and Woofer.

Offline MrRich

Re: Volume control instability
« Reply #5 on: March 24, 2021, 09:47:09 PM »
Hi Eileen,

I don't have the Yamaha Tyros speakers, however, I have the use of two different brands of quality powered monitors which I have hooked up separately and also headphones which I've operated thru the headphone jack...and the volume issue can be noted in each trial.


Offline overover

Re: Volume control instability
« Reply #6 on: March 24, 2021, 10:55:27 PM »
Hi Rich,

you wrote that the Volume problem (randomly changing Volume) occurs on the Main Outs as well as on the Aux Outs and the Headphone output.

Since two separate DAC chips (digital/analog converter) are used internally for these signal paths, the error should be before these DAC chips. And this is exactly where the problem lies, because these two digital signals ("DAC-Data0" and "DAC-Data2") come directly from the Master Tone Generator chip. ("DAC-Data1" signal is used for a third DAC chip and goes to SUB OUT 1/2.)

However, an error that affects the signal paths equally would also be conceivable, e.g. a strongly fluctuating supply voltage for the DAC ICs or the following (analog) OP-Amp ICs.

The internal test program of the Tyros5 offers various test routines for the outputs, but this requires special measuring devices and a lot of experience, so that this can only be carried out by an experienced Yamaha service technician.

If it is absolutely certain that the problem is NOT with the cables / plugs used or with monitor speakers / headphones, and especially if it is not related to switching processes (e.g. Registrations / MIDI songs) on the Tyros5, the only possibility will be have the device checked by a Yamaha technician.

Best regards,
Everyone always said: "This is not possible!" - Then someone came and ... just did it!

Offline MrRich

Re: Volume control instability
« Reply #7 on: March 28, 2021, 06:39:08 PM »
Hey Chris,

Thank you for your time.

Not that I can make much sense of your answer in technical terms....however, I am getting the message. I do feel confident that I have eliminated all causes of this problem being external hardware or user settings/ next step is off to the technician, a process I am dreading, but deeming necessary.

Before closing this thread out I would like to once again say "THANK YOU" to all offering their help. Much appreciated!

Offline overover

Re: Volume control instability
« Reply #8 on: March 28, 2021, 07:19:16 PM »
Thanks for your kind feedback, Rich!

I hope that your volume problem can be solved soon, when a Yamaha technician has looked at the matter!

Best regards,
Everyone always said: "This is not possible!" - Then someone came and ... just did it!