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Posted By: SrMead Couple questions about DSP for the LFR's - 09/10/18 05:29 PM
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
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.
Posted By: SrMead Re: Couple questions about DSP for the LFR's - 09/10/18 11:35 PM
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.
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.
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.
Posted By: brwsaw Re: Couple questions about DSP for the LFR's - 09/11/18 04:23 AM
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.
Posted By: SrMead Re: Couple questions about DSP for the LFR's - 09/11/18 07:04 PM
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.
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?
Posted By: SrMead Re: Couple questions about DSP for the LFR's - 09/12/18 03:36 PM
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
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.
I feel fortunate, MP3z sound fine to me over BT
Originally Posted By Gr8_White_North
I feel fortunate, MP3z sound fine to me over BT


I will generally agree with you. A good recording that has been processed properly with 320Kbps sent over any of the modern BT protocols is getting very hard to tell the difference with an utlra hi-res file. I would hazard to guess that most individuals would have a tough time in blind testing to tell, other than simply guessing.
Yeah i dont like getting into those pissing contests with the audio fools . I can hear the difference between good recordings and bad even with my not so good hearing and for casual listening the MP3 is mostly fine. If i want ti better i plug my phone into the usb on the car. At the end of the day, redbook cd's are fine by me though i do have some SACD's that are quite good. Brothers in Arms is sublime on my M80's from my Oppo on SACD
I would love someone to do an experiment. If you have friends who say they can tell the difference between MP3, CD and SACD (high res).

Play 3 different songs (it doesn't matter what they are just the three need to be different). have one of them an MP3, one a CD recording either FLAC or WAV, but some lossless format. And the last one a HighRes 24/96 or above. Play them in any order you like.

Then get the friend to say which one was recorded in what format. I would bet that no one would get it right other than sheer luck. Without something else to reference it against, I don't think you could tell.

If Axiom has another one of those anniversary parietes, I will definitely be coming up and really want to give this experiment a try.
Such a test can never work because it is the familiarity with ones equipment and song preferences that help you notice the differences. I have a lot of songs on my phone and when play it on shuffle in the car some songs sound great and some dont sound so great so there is differences even with how an MP3 is created. I have original recordings on cd that dont sound as good as other simply becasue they were not mixed well in the beginning so your test would never work. As i said , red book is more than adequate and all this high res bs is just that bs. I have music that has been reissued and it has been remastered and sounds different than the original though not necessarily better. I really dont think there is a test we can do that would prove hi res one way or another because music is so subjective and this is why they get away with pushing all this high res bs. We have a crappy stereo at work thats over 30 yrs old the speakers have had different drivers jammed into them and we stream with an internet radio station and it sounds really good and its more to do with the size of the room than anything else. You want big sound you need a big room.
But that is the whole point. To say that you can tell the difference between an MP3 and a 24/196 that are about as far apart as you can get, why would it make any difference between how where or when it is played?

It's like the coke/pepsi challenge. if you say you like coke over pepsi, if someone handed you a glass you should be able to tell the difference and tell no matter what. I can tell the difference between coke classic and diet coke. they clearly to me taste different.

But when it comes to music, is it we have such lack of sense in perceiving the differences or is it that they are so marginally small that without a back to back ability to rapidly switch between the two that we won't be able to tell the differences.

To tie this back to the original post, I am just trying to prove that really even if there were a difference, would you have the ability to perceive it and know that what you were listening to was in some way inferior to what you could have.

Point. if you like what you hear, does it really matter?
I should probably clarify my comments a bit. I went with 96/24 for recording/ripping but most of my listening is still at 16/44.1.

If you do an absolutely perfect job of filtering/sampling/recording at 16/44.1 I also agree that it would be really tough (perhaps impossible) to tell the difference between that and a higher resolution...

... it just seems relatively rare that perfect job is actually done, and "compress the heck out of it for simplicity" seems more common.
Posted By: Mojo Re: Couple questions about DSP for the LFR's - 09/13/18 07:04 PM
Originally Posted By MatManhasgone
if you like what you hear, does it really matter?


Not until you hear something better.
Originally Posted By MatManhasgone
But that is the whole point. To say that you can tell the difference between an MP3 and a 24/196 that are about as far apart as you can get, why would it make any difference between how where or when it is played?

It's like the coke/pepsi challenge. if you say you like coke over pepsi, if someone handed you a glass you should be able to tell the difference and tell no matter what. I can tell the difference between coke classic and diet coke. they clearly to me taste different.

But when it comes to music, is it we have such lack of sense in perceiving the differences or is it that they are so marginally small that without a back to back ability to rapidly switch between the two that we won't be able to tell the differences.

To tie this back to the original post, I am just trying to prove that really even if there were a difference, would you have the ability to perceive it and know that what you were listening to was in some way inferior to what you could have.

Point. if you like what you hear, does it really matter?


I would try it for sure. It would have to be level balanced since the loudness really affects how we perceive music. I think my taste buds are smarter than my ears.
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