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DSM variable volume on digital out?
2017-09-24, 00:01
Post: #1
DSM variable volume on digital out?
Hi all,

I have the Majik DSM and use it with some DIY hybrid electrostatics, for which it works brilliantly. I'm using a miniDSP active line level crossover that sits between the DSM and a 4 channel amp. What I'd really love to do though is use the internal DSM amp for the HF. The problem is that the only way to do this is to sacrifice the volume control on the DSM, use the analogue outs as amp inputs, and connect the miniDSP to the TOSLINK output instead.

I'm pretty sure I know the answer to this but is there any way of making the digital outputs on the DSM variable volume? This would solve all of my woes and would greatly improve the signal flow as I would only have one stage of digital to analogue conversion.

Volume is an annoying thing to be without though! I can change it on the miniDSP but it's not convenient and won't work with the Kazoo app.
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2017-09-24, 06:50
Post: #2
RE: DSM variable volume on digital out?
I don't have the answer for you, but I hope you realise that if you use the digital outputs you lose the biggest attraction of your DSM, which is the DAC and the surrounding electronics.
Another drawback is that by activating the internal amp would somewhat hurt the performance of the internal electronics as well, but compared to disabling the DAC it should be minute.
But all in all, you would have downgraded your DSM to a cheap DAC and a nice amp.
That's not how source first is meant to be implemented. Wink

So either upgrade your 4 channel amp, or figure out another way to control the volume.



Dangerous bonus option: some subwoofer designs are connected to speaker output terminals and use a very high resistance connection to 'sense' the signal without disturbing it. If you feel comfortable enough you could do the same if you can figure out by how much you'd have to lower the voltage again. I'm only mentioning this as a technical option, but I would not recommend doing this as it will be very easy to damage all the components if you make a slight miscalculation.

Tin can telephone system.
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2017-09-24, 07:12
Post: #3
RE: DSM variable volume on digital out?
As Tin says, using the digital out of the DSM will make it into a transport only. No Space Optimisation, no quality DAC, for those channels. In combo with the other channels you want to use from the analogue out - it would be unbalanced in many ways.
And anyway, the digital outs can't be volume controlled, so it's pretty academic Wink

Akurate EDSM | Majik ExaktBox-I [on Custom Design iRAPs] | Majik 140, REL T5
Rega RP1, [DS214play +Jitterbug, MinimServer], Kazoo [Linx1010]

AV: Marantz NR1506 | B&W 652(C), M1(S), REL T5 (LFE) | Fronts powered by Linn
Net: NetGear DGN2200 | GS108 | AQ Forest x3

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2017-09-24, 10:59
Post: #4
RE: DSM variable volume on digital out?
Gentlemen, thank you. I did not realise that Space Optimisation was disabled on the digital outs. This seems to be a classic Linn thing of handicapping other manufacturers separates because Exact is itself a digital output, and surely that takes advantage of SPACE?

I guess what I was trying to avoid is going digital to analogue out of the Linn, and then analogue to digital to analogue with the miniDSP. The miniDSP uses SHARC processors though which are great. I have them in my Apollo sound card as well and that sounds amazing.

Currently investing the Majik 4100 anyway.
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2017-09-24, 12:12
Post: #5
RE: DSM variable volume on digital out?
(2017-09-24 10:59)Bosco Birdswood Wrote:  Gentlemen, thank you. I did not realise that Space Optimisation was disabled on the digital outs. This seems to be a classic Linn thing of handicapping other manufacturers separates because Exact is itself a digital output, and surely that takes advantage of SPACE?

I guess what I was trying to avoid is going digital to analogue out of the Linn, and then analogue to digital to analogue with the miniDSP. The miniDSP uses SHARC processors though which are great. I have them in my Apollo sound card as well and that sounds amazing.

Currently investing the Majik 4100 anyway.
I'm not sure if it is a deliberate handicapping. If you look at the hardware design of a DS the signal enters the DAC, steps outside to go to the FPGA, does all kind of digital thingies like volume control and SPACE and then returns to the DAC to be converted to an analogue signal.
You have a good point when mentioning Exakt, I don't know exactly what the role of a DS is, for all I know its being reduced to a transport, but I'm sure others will either correct or confirm that.

Tin can telephone system.
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2017-09-24, 12:16 (This post was last modified: 2017-09-24 12:16 by DavidHB.)
Post: #6
RE: DSM variable volume on digital out?
(2017-09-24 10:59)Bosco Birdswood Wrote:  Gentlemen, thank you. I did not realise that Space Optimisation was disabled on the digital outs. This seems to be a classic Linn thing of handicapping other manufacturers separates because Exact is itself a digital output, and surely that takes advantage of SPACE?

Linn do not, in my experience, seek to handicap other manufacturer's products (they leave that to big boys like Apple). What they try to do is to maintain some sort of technical coherence while keeping the system as open as possible. It's a difficult balancing act.

Space Optimisation and (where relevant) Exakt are only provided on the primary output(s) of streaming devices because the setup of those capabilities is speaker- and room-dependent, and not because Linn are trying to exclude other manufacturers. The length of the list of third party speakers that can be used with SO makes that point clear.

SO is not provided on digital outputs partly for the reasons already given and partly because it will typically not be wanted in the use cases of those outputs. As has already been hinted, if you want to bypass the DAC of a Linn DSM in its primary use, there is not much point in buying it in the first place.

David

Main system: [Basik/Basik+/K5/Lejonklou Gaio >][Roksan Kandy Mk III >] KEDSM > Akurate Exaktbox 10 > Linn Silvers> A4200 x 2 and A2200 > K600 > Akubariks
Second system: Kiko
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2017-09-24, 12:27 (This post was last modified: 2017-09-24 12:33 by timster.)
Post: #7
RE: DSM variable volume on digital out?
(2017-09-24 12:12)Tin Wrote:  
(2017-09-24 10:59)Bosco Birdswood Wrote:  Gentlemen, thank you. I did not realise that Space Optimisation was disabled on the digital outs. This seems to be a classic Linn thing of handicapping other manufacturers separates because Exact is itself a digital output, and surely that takes advantage of SPACE?

I guess what I was trying to avoid is going digital to analogue out of the Linn, and then analogue to digital to analogue with the miniDSP. The miniDSP uses SHARC processors though which are great. I have them in my Apollo sound card as well and that sounds amazing.

Currently investing the Majik 4100 anyway.
I'm not sure if it is a deliberate handicapping. If you look at the hardware design of a DS the signal enters the DAC, steps outside to go to the FPGA, does all kind of digital thingies like volume control and SPACE and then returns to the DAC to be converted to an analogue signal.
You have a good point when mentioning Exakt, I don't know exactly what the role of a DS is, for all I know its being reduced to a transport, but I'm sure others will either correct or confirm that.

A DS(M) in Exakt mode is precisely what you say Tin. A (very good) transport and (very good) digital pre-amp. As the OP points out - Space in an Exakt system (ie. SO+) is actually implemented in the Exakt domain, not the pre-amp. (Edit: for hybrids that use both, such as surround, SO is still implemented in the DS for the analogue channels)
If you only ever want to use Exakt, you may as well buy an Exakt-only variant. But that isn't (currently) available at Majik level. And probably won't be - the Akurate is t the right price point for that configuration.

Akurate EDSM | Majik ExaktBox-I [on Custom Design iRAPs] | Majik 140, REL T5
Rega RP1, [DS214play +Jitterbug, MinimServer], Kazoo [Linx1010]

AV: Marantz NR1506 | B&W 652(C), M1(S), REL T5 (LFE) | Fronts powered by Linn
Net: NetGear DGN2200 | GS108 | AQ Forest x3

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2017-09-24, 12:39 (This post was last modified: 2017-09-24 13:18 by Briain.)
Post: #8
RE: DSM variable volume on digital out?
(2017-09-24 10:59)Bosco Birdswood Wrote:  Gentlemen, thank you. I did not realise that Space Optimisation was disabled on the digital outs. This seems to be a classic Linn thing of handicapping other manufacturers separates because Exact is itself a digital output, and surely that takes advantage of SPACE?

I guess what I was trying to avoid is going digital to analogue out of the Linn, and then analogue to digital to analogue with the miniDSP. The miniDSP uses SHARC processors though which are great. I have them in my Apollo sound card as well and that sounds amazing.

Currently investing the Majik 4100 anyway.

Hi

I suspect it wasn't done for that reason, but more that Linn simply didn't consider that anyone would want to bypass their own DAC. As SO (or DVC) isn't applied to S/PDIF, that would imply these stages happen after the stage where that digital output is generated and thus it might not be possible for Linn to re-route it (via a firmware update) to be generated after the SO and DVC processes; that might even require a hardware change (only Linn Design could answer that one; perhaps they already have in another thread, so it might be worth spending some time searching the forum in case they already have done).

The thing is that when the first DS came out, Linn had no DVC and no SO; these are relatively new features and thus when the DS hardware was initially designed, Linn would likely not have considered any need to derive a digital output post 'processing' as there were no user applied processes (i.e. DVC or SO) in the product range.

Bri

PS I love the miniDSP boxes and I use miniDSP 2 x 8 to feed my sub. My pre-amplifier's balanced outputs go to my active speakers and its unbalanced outputs feed into the miniDSP's analogue inputs. The signal is then digitised and I apply a delay (to time align the sub to the mains; it is a rear sub and 4 ms closer to me than the speakers are in front). I also combine the L&R channels and apply the roll-on and roll-off filters, then the signal is passed through the DAC and fed up a single cable to the sub's analogue input.

Interestingly, though the main speakers bass units roll off at 85 Hz (4th order LR) I found the miniDSP sounded best when rolled off at about 65 Hz (and using a 4th order Butterworth). Later, I measured the phase response of the signal being fed to the bass unit of the main speaker and the signal being fed to the bass unit in the sub. After some experimentation, I found that the phase shifts were best aligned (i.e. best track each other) with theDSP set to use a 63 Hz Butterworth (4th order) so that was why I had found that first setting by ear (and that I was surprisingly close to it being optimally set); amazing what ears can do in the absence of test equipment! Smile

I am often almost tempted to get the new 2x4 HD to see how it sounds (I'd be using it in IIR mode to match the phase of my existing speakers) but to be honest, the old 2 x 8 sounds fabulous (it is only feeding a sub, so I doubt the new SHARC would sound any better, when used in that roll).

KDS/1 (music) + ADSM (AV) -> KK/1 -> 350A + miniDSP time & phase aligned 345 rear sub
KDS Renew -> Homebrew fixed attenuator -> 2250/D -> 212 and Sizmik front sub (bedroom)
MDSI -> 104C (awaiting installation in my kitchen)
MDSI -> Shahinian Arc (installed at my mum's house)
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2017-09-24, 13:09
Post: #9
RE: DSM variable volume on digital out?
Hi Bri, you raise some very interesting points there actually. It probably is due to exactly that; signal chain and the fact the hardware predates the software. It's also a rare usage case as most speakers with active crossovers use their own amps internally.

David, you also make a fair point regarding the number of 3rd party speakers SO has profiles for. My counter argument to your "not much point" comment is that even if you only use the digital outs on the DSM it acts as a digital preamp / front end for my other components (of which there are becoming fewer and fewer of course). I originally looked at the DS as I didn't want to pay for an amp I didn't need but then I realised the DS was just a transport and nothing else.

With regards the miniDSP they are amazing for the money. I remember when I first bypassed the passive crossovers in my B&W CM5s and used the miniDSP instead. It was night and day. Linn are one of the only manufacturers who openly criticise passive crossovers and were way ahead of the pack in offering active solutions.

I wonder if I could replicate the SO EQs with the miniDSP convincingly? I don't believe SPACE processes anything in the time domain?

Finalyy, one thing I will say is that the DSM amp is much better than the amp I'm currently using. Definitely justifies looking into the 4100.
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2017-09-24, 13:49
Post: #10
RE: DSM variable volume on digital out?
(2017-09-24 13:09)Bosco Birdswood Wrote:  I wonder if I could replicate the SO EQs with the miniDSP convincingly? I don't believe SPACE processes anything in the time domain?

Finalyy, one thing I will say is that the DSM amp is much better than the amp I'm currently using. Definitely justifies looking into the 4100.

Hi

I haven't paid much attention to the FIR versions, but I did briefly look (shortly after they first appeared) and I seem to remember that folks were designing compilers to enable them to be set up as linear phase crossovers (and perhaps even facilitate corrections to be applied for unit and cabinet anomalies, as Linn do in Exakt; of course, you'd need to build your own anechoic chamber to measure such things; that could be the tricky part). As SO is done in the DS, it will be using IIR and thus there will be small phase wiggles (but likely they are quite small due to the nature of the dips it applies) so I guess it might be possible to do SO in the miniDSP, and as you'd be using FIR, the wiggles would be a lot less.

Apologies if any of the above is incorrect; my field is in matters of radio and my knowledge of FIR technology is very limited (one day, I must rectify that).

Bri

PS Are you aware of anyone (with ears like our ones) having compared the traditional miniDSP to the new SHARK based ones (in terms of sound quality when both are used in IIR mode) and commented on same?

KDS/1 (music) + ADSM (AV) -> KK/1 -> 350A + miniDSP time & phase aligned 345 rear sub
KDS Renew -> Homebrew fixed attenuator -> 2250/D -> 212 and Sizmik front sub (bedroom)
MDSI -> 104C (awaiting installation in my kitchen)
MDSI -> Shahinian Arc (installed at my mum's house)
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