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Couple questions about DSP for the LFR's
#430004 09/10/18 05:29 PM
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Hi gang,

I'm considering getting a pair of LFR1100's to upgrade my stereo/HT system. Been reading up on the required DSP module and have a couple of questions:

1. Is there a way to have 2 different sources going into the DSP module? I'm considering one source for stereo/music (higher quality) and a different one for HT. What's the best way to set things up so I can toggle between these 2 sources?

2. If I understand correctly, the DSP converts an analog signal back to digital for processing and then again to analog for amplification. Isn't this detrimental? Is there a way to stay digital going into the DSP to avoid all the back and forth?

Sorry if these are dumb questions. Just trying to wrap my head around all this new architecture - last time I set up my system was 14 yrs ago so I have a lot of catching up to do on new tech =)

Thanks guys

Re: Couple questions about DSP for the LFR's
SrMead #430006 09/10/18 08:38 PM
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Not dumb questions at all.

There is a version of the DSP which includes a built-in 4-channel amplifier and selectable inputs. The page does not mention a standalone DSP (for use with separate amplification) with those selectable inputs but it would be worth asking Axiom if such a thing was possible.

Quote:
Then there are two version of and integrated DSP and amplifier. Both versions include our ADA1000-4 amplifier with the DSP built into it. The one version accepts either a pre-out or high level (speaker wire) out from your pre-amp or receiver. The other version will accept up to 3 independent sources (i-pod, CD player, etc) and has an input selector switch, a balance control, and a volume control on the front panel.


re: avoiding another A-D/D-A pass, even if you had digital inputs I imagine the DSP would have to re-sample from <input sample frequency> to <DSP sample frequency of 96 KHz> anyways. I guess it would be nice to avoid going through analog if your receiver / pre-pro could output 24-bit 96 KHz over HDMI... no idea if that is common though. I haven't heard any mention of digital inputs on the DSP though.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
Re: Couple questions about DSP for the LFR's
SrMead #430007 09/10/18 11:35 PM
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Thanks, Bridgman. I still have to decide whether I want to go with separate amplification or not. That integrated DSP/amp with selector sounds just like what I need!

Regarding signal conversion, I wonder how detrimental each pass could be. Let's say I'm feeding the DSP a high quality signal obtained from a 24/192 source by a high-end DAC... would it degrade in the DSP unit? I've read that frequency is less important that bit depth so maybe the potential loss is inaudible.

Re: Couple questions about DSP for the LFR's
SrMead #430009 09/11/18 03:12 AM
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Why would it degrade it at all? Its that sort of BS advert they always like to put out that shows a nice ultra smooth sine wave with the words Analog, and then they show a jagged 4 bit step representation beside it calling it digital.

Look at actual music sounds on an oscilloscope and it isn't all that nice clean smooth curves. Then look at reality of signal to noise ratio of all the analog sources that you can get and then compare it to that of CD @ 16/44 and it rivals just about everything out there. You are more likely to get far more noise picked up from the length of wire running from your amp to the actual speakers than you will get induced from converting your analog signal back into a digital form so that the rear speaker offset can be calculated then it sent back to the analog domain.


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: Couple questions about DSP for the LFR's
SrMead #430010 09/11/18 03:16 AM
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Another option you have is to get the LFR with the amps built inside. That way you don't even need the DSP at all. it is done purely inside the speaker.


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: Couple questions about DSP for the LFR's
MatManhasgone #430011 09/11/18 04:23 AM
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Originally Posted By MatManhasgone
You are more likely to get far more noise picked up from the length of wire running from your amp to the actual speakers than you will get induced from converting your analog signal back into a digital form


I always wondered if there would be a percievable difference when running longer cables vs having the amp between/behind the speakers.
I'm kind of hoping that using a larger inwall/sheilded cable is all thats really needed.




Re: Couple questions about DSP for the LFR's
MatManhasgone #430012 09/11/18 07:04 PM
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Originally Posted By MatManhasgone
Why would it degrade it at all? Its that sort of BS advert they always like to put out that shows a nice ultra smooth sine wave with the words Analog, and then they show a jagged 4 bit step representation beside it calling it digital.


I'm aware of the "hoax" of a digital signal being a jagged line smile I'm just wondering if there could be a theoretical loss (since the DSP module maxes out at 24/96) if you're coming from an original source of higher quality like 24/192. If your point is that other factors weigh much more in terms of the end result, I'm ready to agree with it. Just wondering in the theoretical realm.

Re: Couple questions about DSP for the LFR's
SrMead #430017 09/12/18 12:16 PM
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If you ask me, 24/192 is little more than a marketing hoax. Sure as you take more samples or use a larger bit depth you theoretically get closer and closer to an exact digital copy, but you are doing so with more effort and zero gain.

In sound, it really all comes down to signal to noise ratio. I don't know about you, but I cannot and would not ever know if any given piece of music listened to is correct or not? it could be off in timing flutter by +/- 5 ms and I'd never know. it could be played too fast or slow affecting the pitch and I couldn't tell. But I can hear noise. A pop crackle or erroneous hum I can perceive.

There are those who live by the belief that a vinyl record gives a more true sound as it's analog than a digital source. Yet a digital source has a much greater signal to noise ratio, and the electronics are more likely to be timed within a tighter tolerance. Your record player likely doesn't have a regulated power supply connected to the drive motor so it could be wavering all over the place with speed as electricity from your mains is not a perfect fixed voltage.

So comes back to the question of what is perfect sound when listening to your favourite song?


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: Couple questions about DSP for the LFR's
SrMead #430019 09/12/18 03:36 PM
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Thanks for your perspective, Mat. It's easy to get carried away with specs and numbers in this hobby so a good dose of grounding is always healthy smile

Re: Couple questions about DSP for the LFR's
SrMead #430027 09/12/18 09:36 PM
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Yep, grounding is important too laugh

Seriously, my unconfirmed impression (it might be unconfirmed but I make decisions based on it) is that once you get past 24 bit / 96 KHz there isn't really anything more to be had by going further... and that if something like 20 bit / 60 KHz existed that would probably be just as good...

I like 24 bit rather than 16 so I don't have to be as paranoid about recording levels, and 96 KHz rather than 44.1 because I had enough bad experiences with early CDs and poor filtering before A/D conversion to ever really trust 16/44.1 again.

Last edited by bridgman; 09/12/18 09:49 PM.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
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