Problem minidsp/sure + powersoft digimod
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URL: https://forum.speakerplans.com/forum_posts.asp?TID=108657
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Topic: Problem minidsp/sure + powersoft digimod
Posted By: Angelow
Subject: Problem minidsp/sure + powersoft digimod
Date Posted: 31 July 2024 at 5:28pm
| Hi everyone, I have a mini dsp that I want to use to bi-amp some speakers. I have some powersoft digimod 1000 and 500 that can be used both unbalanced and balanced, but the output level of the Mini dsp with an RCA connector is too low in terms of volume to be able to drive the amplifier. I tried some adau modules from sure and the result is the same. Where can I buy a PCB that acts as a preamplifier between the DSP and the amplifier? AliExpress? How should I search? Do you have any links? Thanks |
Replies:
Posted By: VECTORDJ
Date Posted: 01 August 2024 at 1:17pm
| Buy a Real Crossover/DSP.....DBX Driverack is very Good for the Money. |
Posted By: KDW32
Date Posted: 01 August 2024 at 6:03pm
I think he's trying to make an active box
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VECTORDJ wrote:Posted By: Elliot Thompson
Date Posted: 02 August 2024 at 3:03am
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What you are looking for is a Distribution Amplifier. The Aphex 120 Distribution Amplifier will deliver close to 14 volts on it's balanced output. Best Regards, ------------- Elliot Thompson |
Posted By: Angelow
Date Posted: 04 August 2024 at 9:41am
| hi, i need it for an active speaker box |
Posted By: Elliot Thompson
Date Posted: 05 August 2024 at 1:59am
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So, you rather not feed the MiniDSP into a Distribution Amplifier to a powered box? Your limiting factor is MiniDSP as it is a Home Audio grade Crossover Network. You are basically going from one extreme to another. Best Regards, ------------- Elliot Thompson |
Posted By: fudge22
Date Posted: 05 August 2024 at 10:17am
|
From the first post, it would appear that the miniDSP is
being used as a crossover. A separate amplifier for each output is thus
required. The distribution amplifier you mentioned is a 1 in 4 out. He would
need 2 of them per cabinet. RDL do a number of more suitable unbalanced to balanced
converters, but they are pricey. There was no mention of where the completed system is to be
used, so if it is to be used at home I guess home audio grade is fine. The only
problem, irrespective of use, is the limited output level of the dsp, or
looking at it the other way, the lack of gain in the digimod. If Angelow can use a soldering iron, making a custom
preamplifier board, with a few op-amps, resistors and capacitors, would not be
too difficult. Do a web search for balanced line out circuits. Most audio
equipment uses variations on the same circuit. It might also be worth checking
to see if the gain of the analogue output stage of the dsp can be modified to
give more output. A search on AliExpress for “preamplifier boards” brings up
plenty of results. Whether any are suitable I can’t say. |
Posted By: Elliot Thompson
Date Posted: 05 August 2024 at 10:38am
Distribution Amplifiers are offered in many configurations. The one I mentioned (own) is an example what you can expect in terms of output voltage. Angelow will need to research the right Distribution Amplifier for his requirements. As Angelow is using a Powersoft Module, he is going to have to invest in the proper tools to fill in the gap, if he wants to use miniDSP. Best Regards, ------------- Elliot Thompson |
Posted By: fudge22
Date Posted: 05 August 2024 at 10:52am
|
Thanks for clarifying that you agree the device you
suggested is unsuitable for the OP. |
Posted By: Elliot Thompson
Date Posted: 05 August 2024 at 10:57am
I prefer giving ideas so many can explore multiple options by a means of research. Best Regards, ------------- Elliot Thompson |
Posted By: Robbo
Date Posted: 05 August 2024 at 11:51am
| I know that this may sound a bit obvious but have you tried making up a single co-ax lead from the unbalanced RCA connector to a male XLR and wiring the XLR pins as pin 2 live and pin 1 linked together to pin3 thus unbalancing the XLR end of the lead. |
Posted By: Angelow
Date Posted: 06 August 2024 at 11:14am
|
Hi, I've already tried to make the cable, but the problem is the voltage coming from the mini dsp! On AliExpress I can't find anything that is small and can be inserted into a small case. More than balanced, you need an adapter from -10 to + 4 dbu |
Posted By: studio45
Date Posted: 07 August 2024 at 2:00pm
You could make some opamp circuits that give you the required gain quite easily. Here is the basic diagram for a non-inverting opamp gain stage: To get the gain you need, use 10k for R1 and 39k for R2. This gives an output (Vs) of about 1.24v RMS (+4dBu) for an input (Ve) of 0.32v RMS (-10dBv). It makes a 3.9x voltage multiplier. You will also need a couple of extra components to make the real circuit: - A 100k resistor from +IN to GND, this stops the input floating and potentially producing a high DC output if disconnected. - A 100r resistor in series with the output, this helps the opamp cope with driving subsequent cabling. - And, a 100nF cap from power + to - on the board near the chip, this stops oscillations. If you already have or can easily make a +/- 15v supply in the project, just use that to power the opamp. Otherwise, if you only have a single-ended supply, you will also need to use one opamp to generate a virtual ground at 1/2 V+, use that as your ground node inside the opamp circuit, and add 1uF non polar capacitors at the input and output to couple the AC signal. Note that this circuit will raise the voltage of the whole signal, including noise. I don't think the ADAU1701 has a very good signal-to-noise ratio, so you might still have a problem in the form of excessive hiss when no signal is present - the only solution to that is a better DSP board.
------------- Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA |
Posted By: erick77
Date Posted: 06 September 2024 at 12:39am
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You did not mention if you tried to source the Powersoft DSP cards/boards that were designed to plug in and play in those amps. A 30 second look at the data sheet shows the amps were designed for optional dsp cards. Crown use to do that with PIP cards/input panel for their macro-tech and com-tech amps. Parts-express.com has a number of different dsp cards for integration into a project. Rod Elliot has a number of board designs with available PCB if you want to go analog and make your own crossovers.. https://sound-au.com/index.html Mini DSP have some modular boards that plug and play with each other. Optimize your inputs and outputs the way you want. You do not mention what you are trying to use that is minidsp. does it have headers for different inputs and outputs ? probably does. For example they have "balanced input boards", and probably balanced output boards also... I think you can get that MiniDSP kit stuff at parts express also and ebay of course. ( minidsp started out with build your own kit IIRC ) Oh yeah and rod elliot's ESP (elliot sound products) site has input and output buffer/preamp boards . There is a forum with a community and much more detailed information on the design once you buy a PCB from him. Powersoft still makes the DSP cards for "digi-mod" amps : https://www.powersoft.com/en/products/dsp/dsp-lite-e Given that the Powersoft have dsp card slots in those amps; there are going to be low voltage provisions for said cards or a custom mod...
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