I use DM7 in a active 3 way setup with Roon and Audiolense.
I have a little more noise with DM7 than with other DSPs. The horn is JBL2384 with JBL2451 with Truextent beryllium diaphragm. The amplifier to the horn is Anaview AMS0100 with 20 gain.
I can see that it is possible to individual adjust volume on each channel directly on the unit, will it help?
And it is possible to choose between 4 and 5V. I think it is default 4V in my setup?
Or maybee i should use a 10 dB XLR inline attenuator? Or a series resistor on the compression driver?
Any other suggestions?
I prefer experience in the answer
I have a little more noise with DM7 than with other DSPs. The horn is JBL2384 with JBL2451 with Truextent beryllium diaphragm. The amplifier to the horn is Anaview AMS0100 with 20 gain.
I can see that it is possible to individual adjust volume on each channel directly on the unit, will it help?
And it is possible to choose between 4 and 5V. I think it is default 4V in my setup?
Or maybee i should use a 10 dB XLR inline attenuator? Or a series resistor on the compression driver?
Any other suggestions?
I prefer experience in the answer
A series resistor on the driver doesn't help as it also attenuates the signal. You'd have to turn up the volume which might increases the noise again, depending on where it is generated.
What you need is more signal to noise ratio. Increasing the Topping output to 5V might help, but again depends on where the noise is generated and we don't know that.
Have you tried setting the Topping level to max and using a volume control before the Topping?
BTW I don't think you can set volume for individual channels in the DM7; reading the little user guide it looks like there's only a global volume setting for all 8 channels at the same time.
Jan
What you need is more signal to noise ratio. Increasing the Topping output to 5V might help, but again depends on where the noise is generated and we don't know that.
Have you tried setting the Topping level to max and using a volume control before the Topping?
BTW I don't think you can set volume for individual channels in the DM7; reading the little user guide it looks like there's only a global volume setting for all 8 channels at the same time.
Jan
It is a usb dac, how do i put a volume control in front?
Audiolense is a automatic room correction and crossover sofware:
https://juicehifi.com/
Audiolense is a automatic room correction and crossover sofware:
https://juicehifi.com/
I'm not suggesting putting a physical vol control in front of the DM7 that obviously is bonkers.
But it you can control volume before the DM7, it decreases the DM7 noise. Maybe you can do it in your DSP.
If you do in the DM7, your S/N will not change most likely.
It's all about figuring our where the noise is generated.
If you don't know that you're groping around in the dark - you may strike out lucky, or you may not.
Step 1: figure out the problem; step 2 - fix it.
BTW How do you know you have more noise? How did you verify that?
Jan
But it you can control volume before the DM7, it decreases the DM7 noise. Maybe you can do it in your DSP.
If you do in the DM7, your S/N will not change most likely.
It's all about figuring our where the noise is generated.
If you don't know that you're groping around in the dark - you may strike out lucky, or you may not.
Step 1: figure out the problem; step 2 - fix it.
BTW How do you know you have more noise? How did you verify that?
Jan
Well, not if you increase the gain in the digital domain - right?
It might be that the gain structure is so that the digital signal feeding the DAC is never higher than -50 dBfs - if so, attenuating the drivers with resistors say 20 dB makes it possible to up the digital volume with 20 dB - hence a 20 dB better SNR if the noise came from the DAC analog output stage and not the amplifiers...
//
The possible increased noise isnt huge. But i havent compared with a SPL meter. My other DSP (Groundsound DCN28 has individual analouge volume adjustements on the outputs).
The amplifier is balanced and only 25W and has 20 gain. It is even more quiet than First Watt Sit2. I have tested before.
The dsp i use now is a software in the pc and doesnt have individual volume adjustements.
The Topping DM7 8 channel dac is a USB dac/soundcard
My Q is: will 4 or 5V out on the dac give less noise?
I will test those individual digital volume adjustements in DM7 (see my first post).
The amplifier is balanced and only 25W and has 20 gain. It is even more quiet than First Watt Sit2. I have tested before.
The dsp i use now is a software in the pc and doesnt have individual volume adjustements.
The Topping DM7 8 channel dac is a USB dac/soundcard
My Q is: will 4 or 5V out on the dac give less noise?
I will test those individual digital volume adjustements in DM7 (see my first post).
Are you saying so see the noise difference on an SPL meter?? That's - remarkable.
How do you know it measures just the noise, when a typical living room is orders of magnitude more 'noisy?
How did you measure that?
To your question: it depends where the noise originates. If it originates before the level setting, it just gets bigger with the bigger output.
If it originates after the DAC like in the power amp, your S/N ratio gets better but only 4/5ths which is only about 2dB less which difference is normally not audible.
You need to get more info what's going on before you can fix it, or before realizing there is no issue.
Also, I do not think it is possible to cset individual levels in the DM7. If so, I'd be interested, I would like to do that too, haven't found out if it can be done.
Jan
How do you know it measures just the noise, when a typical living room is orders of magnitude more 'noisy?
How did you measure that?
To your question: it depends where the noise originates. If it originates before the level setting, it just gets bigger with the bigger output.
If it originates after the DAC like in the power amp, your S/N ratio gets better but only 4/5ths which is only about 2dB less which difference is normally not audible.
You need to get more info what's going on before you can fix it, or before realizing there is no issue.
Also, I do not think it is possible to cset individual levels in the DM7. If so, I'd be interested, I would like to do that too, haven't found out if it can be done.
Jan
I would say the noise has to be the opamp noise of the converter, or some noise induced into the cable from the converter to the amplifier due to impedance mismatch, ground loops or some other problems with the simple balanced output of the DAC, But since your other DAC has analogue volume control after the DAC chip I would guess it is simply the unattenuated noise of the DAC opamps. So a line attenuator in between the DAC and the power amp could be a solution. 4V or 5V should make no difference in noise if my suspicion is right.
On the other hand, my dm7 that powers a no baffle speaker setup, where it is now really quite, had some unbearable noise problems until I balanced all the connections to the (originally unbalanced) amps with transformers I had, luckily, lying around. Without those I heard digital noise from the computer in the speakers.
That makes sense. On ASR, the Topping guy was asked about using a balanced to single ended cable on the DAC output, and he said 'don't do it!'.
What it does is short one channel of the bal connection to ground. Nothing breaks, but it's bad in so many ways.
Jan