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Old 4th February 2014, 07:07 AM   #1
Dr Jim is offline Dr Jim  United States
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Default Stereo SPDIF > MiniDigi > (2) MiniDSP > (2)Hifimediy DDX 320 amps?

!!! UPDATE !!! Bit the bullet, bought the NanoDigi & plugin from MiniDSP so my 'stack' of a MiniDigi and two MiniDSP 2x4’s with 2-way and 4-way advanced plugins is for sale. How about $140 including shipping Continental U.S. for assembled, working setup with all cables, SW on USB stick about $200 USD at current prices.

Cheers & thanks


In the process of evolving to a pretty much 'pure digital' system ...

As configured now, an LMS squeezebox server on an Xbuntu 2Tb Host streams to a Logitech Receiver which drives via Toslink a MiniDigi + 2 MiniDsp stack.

Using the MiniDsp 4-way plug-in, channel 1 on the upper MiniDsp is assigned to Left Bass, channel 2 is assigned to the Left Mids, and channel 3 to Left HF.

The bottom MiniDsp maps the same channel assignments to the right channel Bass, Mid, and HF outputs.

The mid (Two 5", 8 Ohm Celestion per side mounted OB) and HF (Linnaeum polymer tweeter) drivers are driven by TA2050 amps, while the bass woofers (two 18" Eminence Sigma drivers in an floor-mounted IB manifold) are driven by a dedicated class D amp of about 250 Watts.

The original plan was to buy another MiniDigi, split my current stack into two MiniDigi+MiniDSP stacks, split the Toslink signal from Logitech Receiver, run 10' Toslinks to each stack, select the appropriate I2S_INPUT pair for either the left or right channel, the push the matching processed I2S_OUTPUT channels from each MiniDSP to the stack's Minidigi's Toslink output and then on via short link to the DDX320V2's inputs.

My untested assumptions are:
  1. That I can split the outgoing Toslink signal and decode it properly at each MiniDsp
  2. That I can pass the processed signa; back through the MiniDigi's Toslink with the correct I2S channel assignments for the DDX320V2 to decode.
  3. And finally that this fershlingener lashup will actually fly.....

Have I missed anything - is there a simpler & more elegant way of routing this data?

Your inputs are always depreciated .... :>



Last edited by Dr Jim; 6th February 2014 at 01:03 AM.
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Old 5th February 2014, 08:15 AM   #2
Dr Jim is offline Dr Jim  United States
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Default Upon further review...

I've been spending some unproductive 'medical time' reading and reviewing the MiniDsp site.

It looks like while the MiniDigi/MiniDsp 2x4 stack is pretty successful as an Analog output solution, its single SPDIF output is pretty limiting - and that for a digitally streamed system, I'd be miles ahead to replace my current stack with a single NanoDigi board.

To my unlearned eye, there are some significant advantages:
  1. The Nano has 4 SPDIF outputs with 8 available channels, I'm currently using 5 channels (L+R Mid, High, and summed mono bass)- room for expansion.
  2. The Nano samples at 96kHz versus 48kHz of the MiniDsp more headroom & lower noise floor?
  3. The crossover functions in the Nano seem roughly similar to the 4-way advanced on the MiniDsp, I wonder if I can export & import my existing setup as Biquads ?

Can someone more familiar comment on the NanoDigi's plug-in capabilities, I'm currently using PEQ, filtering, 2+1 active x-over, and digital time delay - are these features all implemented on the Nano?

If the Nano is a workable solution, I'll gleefully pass along my Mini-stack + plugins for roughly 100 USD, which seems like a fair price & will help keep this upgrade within my very tight budget.


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Old 7th February 2014, 02:14 AM   #3
minidsp is offline minidsp  Hong Kong
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Knowing your setup, the nanoDIGI would indeed be the best way to set your system. Using the Hifimediy DDX spdif amps is the cleanest setup you can hope for.

The nanoDIGI does have more power, more flexibility than the miniDSP kit. A good choice.

__________________ - Low cost & modular audio DSP kits for DIYers - Follow our tweets @ minidsp
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Old 7th February 2014, 04:33 AM   #4
Dr Jim is offline Dr Jim  United States
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Thanks Devteamers...

Hope you had a great New Year's holiday & that the Year of the Horse is healthy, auspicious, and prosperous for you all.

I've been plotting this upgrade for sometime, and would have used two MiniAMPs, but 20W into a 1600sq foot room just didn't seem enough to really rock Infected Mushroom with 89dB tweeters....SIGH!

Pretty excited, these are the last pieces in a puzzle that I've been trying to solve for a number of years, we've exorcized a fair number of audio demons, have driven the noise floor to nearly inaudible levels, and are pleased with the system's spectral & impulse response.

Now it's time to grapple with the hoary shibboleths of Dynamic Range and Inner Detail, wish me luck, I'll either return with my ears, or on them ....


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Old 17th February 2014, 07:40 PM   #5
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Default DDX320 parallel operated ?

Dear Dr Jim,
That's very intersting. I'm moving along the same lines for my all digital setup. Now, I'm experimenting setting up straming/music server for ultimately a nanoDigi --> DDX320 for my new active speakers. I'll get them in two monthes.
No time offset problem paralleling these DDX320 ?
Off topic, DDX320 sound : out of the box, I was very pleased with the very nice dynamic range and great inner detail.
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Old 1st December 2014, 05:28 PM   #6
mwyss is offline mwyss  Switzerland
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Default Volume Control


Do you volume control in miniDigi and let ddx320 on full gain/volume?
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Old 16th December 2014, 06:14 AM   #7
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Hi Martin,
Now, DDX320 are at -6 dB.
Master volume control with nanoDigi.
What is your setup ?
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Old 16th December 2014, 07:36 AM   #8
Dr Jim is offline Dr Jim  United States
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Sorry for ignoring this thread - got seduced by building a headphone station (Fostex T20RP V1 + Burr-Brown PCM1794 eval board + Lehman clone amp) which all sound very nice indeed driven from a Logitech Duet via S/PDIF.

I chickened out on building Arduino-controlled WiFi-enabled stepped attenuators, which are supported by the DDX320's output stages, and still set the system's overall gain at the Raspberry Pi via its Squeezeplayer app.

The NanoDIGI is run @ 0dB (e.g. no attenuation) on the DDx 320 inputs, but the Infinite Baffle Subwoofer is set at -10dB attenuation at its crossover, the OB mid/woofer line array is set for -11.5 dB attenuation, and the ML electrostatic panels are at 0dB attenuation.

The DDX320 has it's input set for +10dB boost, so essentially the subwoofer (two Eminence Sigma 18's in a floor-mounted manifold is run at -10dB, mid/woofers are almost flat at -1.5dB, and the panels are +10dB.

I'm pretty certain that this is a sub-optimal gain structure - and I certainly wouldn't recommend it, or its topology - but I originally built this system to drive fairly efficient OB speakers over the IB sub, and then fell across two pairs of ML Sequels for $225USD total and got sucked back into the trap of Electrostatic Audio Doom from which I have not yet escaped.

The ML panels are somewhat less efficient than the mid/woofers, and the subs (driven by a 250W analog amp fed from a Firestone Audio DAC) are both about 6dB more efficient, and have a higher gain structure that the rest of the chain - so they get pretty severe attenuation.

The seduction of the modified ML panels (crossovers removed, and bias now @4000 VDC) is their brilliant midrange clarity, speed, and imaging stability from 400Hz to 16KHz their resolving power is sometimes astonishing - the entire room becomes headphones.

The price is relatively low efficiency, very nasty capacitive loading in the upper ranges (the EQ is rolled off -1.75 dB from 15kHz on to protect the amps), and moderately poor dispersion.


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