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miniAMP digital pipeline 12 years 3 months ago #164

  • jzagaja
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With miniDIGI->miniDSP->miniAMP one can build a digital pipeline for an active speaker right? Do you have an idea for volume control? Distortion level at 3/4 and full power?

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Re:miniAMP digital pipeline 12 years 3 months ago #165

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Hello,

Why not just control the volume directly in the MiniDSP via potentiometer as described in the Manual on page 10/11 ?

greets,
Complex

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Re:miniAMP digital pipeline 12 years 3 months ago #166

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There's any manual? I haven't seen.

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Re:miniAMP digital pipeline 12 years 3 months ago #171

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jzagaja wrote:

With miniDIGI->miniDSP->miniAMP one can build a digital pipeline for an active speaker right? Do you have an idea for volume control? Distortion level at 3/4 and full power?


Jack,

Yes, that's correct. An active speaker with digital input (SPDIF/Optical) and linking capabilities for the next speaker is indeed the most obvious application for this combo.

Volume control as mentioned by "Complex" can be done in the digital domain on the miniDSP. Have a look at the miniDSP manual as suggested. If you want to control volume of the amplifier, there are currently 4 selectable gain settings on the board (-3/+3/+9/+12 dB). We would typically set the coarse gain with the switch to match the desired output power of the speaker, and then tweak the volume with the digital gain.

Manual for the miniAMP will be out in the next few days. Amplifier is being manufactured as we speak.

Hope this makes sense.
miniDSP, building a DSP community one board at a time.

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Re:miniAMP digital pipeline 12 years 3 months ago #175

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Multichannel global volume control (without PC) is always difficult for DIY. We can buy Chinese 4 channel potentiometer but channel to channel difference is of several dB. Better are the relays, with digital display but who of you DIYers is able to design such?

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Re:miniAMP digital pipeline 12 years 3 months ago #177

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Actually, the digital volume control we're are talking about is a "Master" volume control for all output channels. So only a single 10k/100k pot is enough to be able to control the volume in digital domain. No need for multichannel pot.

Have a look at the user manual for more info on how to connect it.
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Re:miniAMP digital pipeline 12 years 3 months ago #203

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Can a single pot control master volume for two boards?

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Re:miniAMP digital pipeline 12 years 3 months ago #205

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Yes, controlling two boards using a single potentiometer will not cause a problem.
miniDSP, building a DSP community one board at a time.

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Re:miniAMP digital pipeline 12 years 3 months ago #206

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Can I ask how to do it?

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Re:miniAMP digital pipeline 12 years 3 months ago #208

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Can't get volume control. When I turn my pot LED stops blinking but volume remains the same. Why? Pin 9 is center tap.

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Re:miniAMP digital pipeline 12 years 3 months ago #209

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Moreover when I connect switching PSU to the Tripath amp and MiniDSP with its own PSU to the Tripath then I hear loud HF noise like a mistuned radio. Everything is alright except some background hisss when I connect everything to linear PSU.

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Re:miniAMP digital pipeline 12 years 3 months ago #210

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Jacek,

After looking at the manual, we realized the typo. It's supposed to be Pin 5, not pin 9. That pin is the LED control, so indeed it would affect the LED but not the volume. :-)
I've updated the User Manual with a new set of diagrams. Please make sure to have a look at it to confirm the pin-out. Let us know if you have any questions.

With regards to your amplifier/PSU issue, I'm not sure what to make out of this problem since we've never experienced it over here even though we have a wide range of amplifiers, class d/AB. I'm guessing that you've already proved that this background noise is not related to your laptop, am I right? (previous posts)

Please send an email to our tech support team @ This email address is being protected from spambots. You need JavaScript enabled to view it. with some diagrams of your setup and we will take it from there. It will be much easier for us to troubleshoot and track your case.

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Re:miniAMP digital pipeline 12 years 3 months ago #211

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My setup is very simple:

Switching 12V PSU for LCD -> Tripath TA2024 board -> MiniDSP

There are three most important questions:

1) Why do some switching PSUs introduces loud noise in MiniDSP or Tripath? Can switching PSU be used at all?

2) How can I control volume in two or three boards using a single potentiometer?

3) In a typical closed box speaker I use 15dB bass boost. Does it mean I need to decrease master volume so that amplifier input stage will not clip the signal? That means for any serious work 15-25W Class-D is insufficient and miniAMP is to weak.

Maybe a good solution is to take miniIO and connect home cinema amplifier through TOSLINK?

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Re:miniAMP digital pipeline 12 years 3 months ago #212

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Jacek,

In answer to your questions.

1) Why do some switching PSUs introduces loud noise in MiniDSP or Tripath? Can switching PSU be used at all?
miniDSP Team: Boards have been running with switching supplies without any problems/noise, so it must be something else. I believe that we just wrote in our previous post that you should contact our tech support team to open a ticket and let our tech support team follow up this issue. This forum is for basic technical information and if you need additional support, you'll need to contact our tech team directly to make our task of following up cases easier. Hope you can understand.

2) How can I control volume in two or three boards using a single potentiometer?
miniDSP Team: As long as all boards are sharing a same ground (PSU for example), simply connect the center tap pin to more than one board.

3) In a typical closed box speaker I use 15dB bass boost. Does it mean I need to decrease master volume so that amplifier input stage will not clip the signal? That means for any serious work 15-25W Class-D is insufficient and miniAMP is to weak.
miniDSP Team: I'm not sure to fully understand this statement. We have assembled a couple of boxes already in 3/4 way configuration, with or without the miniAMP and it worked very well without any saturation/clipping and even though we're boosting the signal with +15dB. My answer is that it is all gain structure related. As long as you don't exceed the Peak to Peak voltage on the output (2.5Vpp), you'll be fine. In most cases, amplifiers would have a clipping point that is lower than other sources. You just need to know that clipping point. miniAMP is different because it uses I2S (digital audio) to share audio between boards. Clipping point of a miniAMP is 0dBFS (0dB full scale = 24bits of 1) which with any digital audio, you certainly don't want to get even close to! :-)

Hope this makes sense,

miniDSP Team
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Re:miniAMP digital pipeline 12 years 2 months ago #379

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Which pot is better - linear or log?

I've installed motorized pot (Alps type) but it is a bit weird - must double check.

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