Well, with a digital crossover you always need multiple DACs. Fusion is a complete system including DACs and amps. This kind of integration has benefits (no interlinks, preamp, connectors and additional circuits required). My Fusion 253 has three DACs built in, one per channel. You can connect a single DAC to it, but you will have an additional ADC stage then. With a good clock source I now prefer to go digitally in via spdif. But if you like the sound character if your DAC you van connect it, the ADC stage is fairly neutral...
Fedde
--- Answered my own newbie question I think , It looks like the the Hypex Fusion Plate amps take a S/PDIF Input so I could use my own dac...... , but it would be nice not to be locked into the Ncore amps forever though.
- In a perfect world eventually I would like to use my own dac, and my own amplifiers, Is there and easy way to do that?
- EDIT -
-------- Ooops didn't see your post in time - thank you fedde -
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- Kudos and to xrk, jmpmash and mainframe99 for your recent builds!!! Great job on the measurements and very inspirational to the rest of us! Sounds like your really enjoying your music thru your new loudspeakers!
- Do any of you plan on building passive crossovers down the road?
- In a perfect world eventually I would like to use my own dac, and my own amplifiers, Is there and easy way to do that?
- EDIT -
-------- Ooops didn't see your post in time - thank you fedde -
------------------------------------------------------------
- Kudos and to xrk, jmpmash and mainframe99 for your recent builds!!! Great job on the measurements and very inspirational to the rest of us! Sounds like your really enjoying your music thru your new loudspeakers!
- Do any of you plan on building passive crossovers down the road?
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I used to think that too..... but found out the long and hard way, that building a good loudspeaker cabinet, do good measurements and adjusting the DSP correctly.... is way - WAY more important for a good result
The beauty of using a Hypex amp is that there is no need for a DAC. If you use a DAC, the output will just be converted back to digital, which means you have introduce two unnecessary conversions to the process.
Here's the Hypex block diagram showing the digital and analogue paths:
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Mine is passive Harsch XO (quasi transient perfect asymmetric 4th/2nd order).
Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
A bit off topic, but I always wonder why even go through the analog stage. The sigma-delta stage of a DAC looks very similar to the signal+carrier in a class D amp. if they can feed that directly from the sigma-delta into the class D output stage, would that skip the whole process of converting to analog and then back again?
I have a minidsp that has SPDIF in/out so the active crossover is completely done in digital domain without ADC/DAC until the output where I need 2x stereo DAC. It is ok to do. But my particular model doesn't support FIR filters so I am looking into alternative solution.
You are welcome! I am learning as I go.
I do plan to build a passive crossover. I have been relying on DSP crossover for all my previous builds and I want to take that extra leap to learning how to design a passive one.
I believe that's what's done in the Steinway Lyngdorf amps.
Fully digital systems | Steinway Lyngdorf | The world's finest audio systems
This has been tried, but the practical problem with it is that it basically has to be an open-loop implementation. The time delay in running the output through an A/D and then a DSP feedback process renders the use of feedback impractical if not impossible.
Now that we have extremely good conventional D/A processes and also very good conventional Class D implementations, it turns out that it's cheaper, easier, and better to use the conventional approach.
NAD did get decent results with their implementatiion, but it appears at this point that even they have drifted away from this in more recent models.
- Hi , sorry for such basic questions - ( newbie here) ... so your minidsp unit requires two dacs after the active filter that's in the unit? . . . .
- Q - what are the FIR filters , and why are they necessary to your minidsp active filter - or to your application?
- Q ... what alternate solutions are you looking at?
----- Thank you for your help ,
I can offer some help here. No shame in being new (joined 2008??). Yes, if you are using a dsp system that is digital in and digital out, you will need dacs for each channel that you are putting out. For example my setup has 4 channels (2 low freq L and R, 2 high freq L and R) out therefore I use two stereo DACs.
If you are just getting started, don’t worry about FIR filters. They are a luxury and hard(er) work, and the IIR filters in a cheap DSP do a perfect job for getting you 99.8% of the way “there”.
I’d assume by alternative solutions he’d mean either different miniDSP models or different DSP manufacturers altogether. There are several. MiniDSP is probably the cheapest to get started. The cheapest all digital MiniDSP model I believe does not support FIR filters, and they require much more digital processing power so you need to spend more to get them.
I originally planned to use a MiniDSP HD for crossing over to subwoofers, but I'm now considering the freeDSP-aurora. Need to do more research on it though.
Like you, I'd welcome any thoughts on it.
Another one to consider is Analog Devices ADAU1452 EVM board. It has the 1452 which is technically superior to the 1701 used in basic miniDSP. It is 4x8 and capable of high speed sample rates internally. Also has FIR capability and a huge toolbox of DSP filters and tools available for free with Sigma DSP Studio GUI based software. It will let you have complete control over all capabilities of the DSP. I got one of these to develop my own custom DSP with premium AKM ADCs and DACs and find that the sound quality of the EVM is very good and the capabilities are immense. Takes a little more learning to get up to speed but not that hard. Also has built in SPDIF (optical in/out) and can have I2S or SPI accessories added to it (I connected external DACs via I2S and Bluetooth no problem).
EVAL-ADAU1452REVBZ Analog Devices | Mouser
Here is SigmaStudio:
SigmaStudio(R) | Analog Devices
EVAL-ADAU1452REVBZ Analog Devices | Mouser
Here is SigmaStudio:
SigmaStudio(R) | Analog Devices
Isn't the Aurora basically the same but with the 8 "free" channels of DAC and USB input?
Zetex have done this too and used to have a complete multichip solution that used an ADC with digital input and post filter feedback. They never released it to the general public though. I'm guessing that the system complexity, with regards to tuning the control loops for maximum performance and stability, along with needing the hardware to be implemented to ensure stability, wouldn't be a trivial matter. Any time you change a system parameter, such as different layout, different output inductor, different output capacitor, different output inductance/capacitance and their parasitics...these could all necessitate retuning of the control loop. It's possible that a properly optimised system usually required direct input from a Zetex engineer too. Something they'd be happy to offer for a large company only. I can't say I ever saw a commercial product using it either, or was the NAD based on it?
The original TacT did not used post filter feedback and neither did a number of Lyngdorfs subsequent releases. In fact I am not sure if they even use that now.