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miniDSP Low cost, modular Digital Signal Processor (DSP) kits for the DIYer from miniDSP.

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Old 16th February 2014, 10:31 PM   #1
gekados is offline gekados
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Default MiniDSP (or other module) between pre and poweramp

Hi.

Been reading for days now, and I've gotten quite confused by this point.
I'm trying to find a good solution for my system and advice would be greatly appreciated.

First i'll outline my setup :

I have 4 speakers, two tops and 2 passive subs.
Today I use the crossover from my preamp to split signal at 80hz.
I have a 5-channel poweramp of which I use 4 channels.
Source is a dedicated mediacenter pc.

The first issue is that my preamp only has 1 sub out, so I have to y-split the signal to subs and therefore only gets mono bass.
Next issue is that the crossover in my preamp is horrible.
Third issue is my room which gives me evil spikes around 40-50hz, resulting in very boomy bass.
Last issue is that I want the best possible sound quality

My initial idea was a minidsp between pre and poweramp, using peq to compensate for room and crossover for splitting signal properbly (my speakers need a really steep filter). It sounds like a wonderful best of all worlds solution. But the miniDSP samples everything to 48khz it seems. Which has me worried for a lot of my music is either 44.1, 96 or even 192khz. And even though the dac in my preamp isn't exactly worldclass, it would be sad to resample signal after it leaves the preamp.

So I was wondering if there was another solution to get both crossover ability and room compensation without resampling the signal 'so much' ?

My first idea was minidigi/minidsp, but that would have to be before preamp and then I couldn't use it as a crossover solution. But that would be a solution for room compensation.
But the crossover can't be done without resampling signal to either 48 or 96khz ?

And yes, i know, a lot of people says it makes no difference. But I believe it does, on my system there is a difference (not big, but it's there), between 44.1 and 192khz signals, and 48khz is just not good for anything but movies, which natively are 48khz anyway.

What I'm really looking for is a 'pass-through' crossover solution, with no resampling between pre and poweramp. Would that be possible in any way?


Excuse my rambling, but I would appriciate any input the community might have on this one - even a simple 'it can't be done' would at least put my mind to rest.

Thanks in advance and best regards,
Lars
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Old 17th February 2014, 10:49 AM   #2
lduarte1973 is offline lduarte1973  Portugal
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minidsp has plugins that work at 24 / 96 khz ( the 4x10 and 10x10 units ) havent seen any plugin for 192khz , it always resamples to the freq the plugin works on , with it maybe you wont need that preamp/dac you have but i cant know without testing. Minidsp xover peqs and filters are very good , no problem with that . i have a dac that resamples everything back to 192khz , maybe you can use one like that for the main speakers , no need for high resolution on subs.

Last edited by lduarte1973; 17th February 2014 at 10:54 AM.
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Old 19th February 2014, 12:34 PM   #3
JohnR is offline JohnR  Australia
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Quote:
Originally Posted by lduarte1973 View Post
minidsp has plugins that work at 24 / 96 khz ( the 4x10 and 10x10 units ) havent seen any plugin for 192khz.
I think the 10x10 runs at 48 kHz. I'm not aware of any units that run (internally) at 192 kHz. The simple reason is that it takes twice the DSP power, or to look at at another way, halves the effective amount of processing you can do.
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Old 19th February 2014, 12:43 PM   #4
JohnR is offline JohnR  Australia
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Quote:
Originally Posted by gekados View Post
What I'm really looking for is a 'pass-through' crossover solution, with no resampling between pre and poweramp. Would that be possible in any way?
Hi, if you put a DSP unit between preamp and power amp, then it will sample at some rate and output at (usually) the same rate. The bandwidth will be limited to half the sample rate. There is however no sample rate conversion being done digitally in this case, but there is an "extra" set of A/D and D/A conversions - however that is unavoidable if you put a DSP unit between your (analogue) preamp and poweramp.

These days, personally I think the optimal solution is to do all processing digitally before a final conversion to analog, in as many channels as needed. I don't think we're totally there yet but I think it's inevitable.
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Old 19th February 2014, 04:13 PM   #5
lduarte1973 is offline lduarte1973  Portugal
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4x10 plug-in | MiniDSP See 2x8/8x8 tab , says 96

https://www.minidsp.com/products/min...inidsp-4x10-hd , says 96 too

Last edited by lduarte1973; 19th February 2014 at 04:15 PM.
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Old 19th February 2014, 06:02 PM   #6
gekados is offline gekados
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Quote:
Originally Posted by JohnR View Post
Hi, if you put a DSP unit between preamp and power amp, then it will sample at some rate and output at (usually) the same rate. The bandwidth will be limited to half the sample rate. There is however no sample rate conversion being done digitally in this case, but there is an "extra" set of A/D and D/A conversions - however that is unavoidable if you put a DSP unit between your (analogue) preamp and poweramp.

These days, personally I think the optimal solution is to do all processing digitally before a final conversion to analog, in as many channels as needed. I don't think we're totally there yet but I think it's inevitable.
Hi John.

Thanks for the info.
I'm feeling really allergic to the extra adc/dac and that stage in the chain.
So I think i'm going for an analog filter for crossover. There is such a one for my speakers, but it's needlessly expensive, but hey, it's the right solution I believe.

I will need some sort of room treatment though, but that would mean I cut do that between source and preamp. Only for one source though, but that would be ok. My PS3 is only used for watching football anyway, hardly any 45hz spikes in that material

A follow-up question :
Since i'm using toslink out from my htpc, i would like to switch to usb out instead. Any suggested solution for setup between htpc/preamp which would enable me to use "usb-dac" and peq ? I know nothing about is2..

Best regards.
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Old 19th February 2014, 09:49 PM   #7
JohnR is offline JohnR  Australia
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Quote:
Originally Posted by lduarte1973 View Post
4x10 plug-in | MiniDSP See 2x8/8x8 tab , says 96
Yes, the 4x10 runs at 96 kHz, the 10x10 runs at 48 kHz.
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Old 27th February 2014, 06:22 PM   #8
DWP is offline DWP  United States
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The first thing I did after properly setting up my MiniDSP 2x8 using the 4x10 plug-in was get rid of my preamp. I added a rotary source selector for additional analog inputs and used the optional pot MiniDSP offers for attenuation. A couple months ago I also added MiniDSP's Vol-FP and Digi-FP which gives me additional digital inputs + remote volume and digital source selection. Much more of a DIY approach but now the 2x8 is also a very decent pre, I even added a phono pre to the box. I put my creation with pics up on the MiniDSP forums here if you're interested but it has evolved a bit more since that post was made.


Also, I believe any volume attenuation should be done at the DSP or after it in the audio chain for best possible sound quality and it certainly helps in getting the correct gain stage going into the DSP.
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