# Does a DSP minimize the need for an SQ head unit?



## elk88 (Dec 7, 2012)

Long time lurker, first time poster (so be gentle :laugh

I've done a bit of searching but I haven't found what I'm looking for (if I'm just missing it and someone one wants to redirect me to the appropriate thread, please feel free and I'll do my own homework).

I'm curious if having a DSP minimizes the need for having an SQ style head unit?

I recognize that some SQ head units offer things like optical outputs to maximize quality but it seems in a lot of cases that the head unit just becomes a pre-amp for the DSP. A fair amount of SQ head units seem to include features that a DSP has which I believe is part of what classified them as SQ head units. It would stand to reason then if you're going to incorporate a DSP, that a lot of those features wouldn't be used (hence raises my question). If any of this babble is correct, then I would assume having a strong/clean signal for the DSP to work with is what I really should be after and don't necessarily need an SQ head unit?

I'm looking at a Helix DSP Pro Mk2 and trying to pair it with a suitable head unit (to maximize SQ) but unsure of what I should be considering (suggestions absolutely welcome but please keep in mind I'm still stuck in the 90's with a majority of my collection in CD form  Which means things like the Sony RSX-GS9 probably aren't the right choice for me).

For reference sake (and off-topic in my own post - haha), I ?_think_? I can class myself as 'old school' with most of my involvement (and gear) being from the 90's (92-2000). This really feels like I'm having a mid-life crisis trying to start this all up again (although I don't intend to compete again and hopefully won't start the merry-go-round of equipment & installs). What this means though is that I'm in way over my head with a lot of this DSP stuff and digital music (my entire music collection is records/tapes for home and CD's for car - haha). If any one is curious, the majority of my gear is still in excellent condition and being brought out of storage for use. Most of what I still have is PPI (PC2150, PC2350, EPX223, 2x DEQ-230), Alpine CDA-7949 w/ tos link changer and a boat load of different speakers/subs that I've used throughout the years (FYI this is not a sales pitch either - I'm not looking to sell anything - my oldest son is almost 16 and when he gets his first car, I'm aiming to set him up with the gear I don't use). My intent is to add a new HU (recommendations welcome), a DSP and since I'll be going with an active crossover set up, a multi-channel amp for the front stage (right now I'm considering the TRU B41-S). I'll likely swap out speakers too (looking at the Hertz Mille line). For what it's worth, I'm just trying to get back to 'that one car'. Doesn't matter how much gear I've been through in the past or setups/ installs I've had in multiple vehicles, there's still that 'one' that stands out among the rest and I'm aiming to get back to it again.

Anywho, now that I've derailed my own thread, any input on whether having a high-end/SQ head unit with a DSP is worth it or a waste, would be great (and again HU suggestions are welcome).

Thanks in advance


elk


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## SkizeR (Apr 19, 2011)

The benefits of an "SQ" head unit are low distortion, low noise floor, etc etc.. A dsp can't fix either of these so a good source is still important

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## Lycancatt (Apr 11, 2010)

and you own one of the better ones in that alpine you listed above, so get your son a pioneer 4200 nex which he'll appreciate the flexibility of and run from there.


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## elk88 (Dec 7, 2012)

Lycancatt said:


> and you own one of the better ones in that alpine you listed above, so get your son a pioneer 4200 nex which he'll appreciate the flexibility of and run from there.


That's pretty much the root of why I was asking the question and the reason for wanting to change the HU (the kids). While this is ultimately for my own personal enjoyment, I am trying to incorporate them into the experience as best as I can. They want to be able to connect all their toys and listen to their own stuff and I was hoping I could make that happen without making a lot of sacrifices. Maybe get them to appreciate the listening experience and expect a little more from their music quality (hard to understand there is a difference until you can actually hear the difference). I had hoped I could compensate somewhat with a DSP by giving a little away on the HU to gain; as you said, flexibility. Am I dreaming/asking too much with something like the pioneer you suggested? 

elk


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## smgreen20 (Oct 13, 2006)

The adage goes, you're only as good as your weakest link. Same applies here.
I'm also what you call an old schooler. I run LANZAR Opti amps currently with a modern day Phoenix Gold amp for sub duty. 

Soon I'll be switching back to OS speakers and going with LANZAR. Might keep the Opti amps, but am thinking of going back to my Clarion 6ch A4600 to keep the space down.


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## sapatel20 (Feb 4, 2017)

SkizeR said:


> The benefits of an "SQ" head unit are low distortion, low noise floor, etc etc.. A dsp can't fix either of these so a good source is still important
> 
> Sent from my VS988 using Tapatalk




Then DSP is waste if we pair it with stock HU from Car manufacturers? Actually i am planning to add mosconi 4to6 or other basic 6 ch dsp with my stock fiat punto stereo made by Harman. If its like that way only then what is a good option to keep stock HU and aiming for SQ Music.

Stuff which i have as of now:
Stock player without touch but with 7 band EQ.
Iso to Hi low converter 
Morel maximo components at front and cox at rear
Dayton ultimax 10 sub sealed
Alpine pdx v9

Please advise.




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## Jlugo360 (Mar 6, 2017)

sapatel20 said:


> Then DSP is waste if we pair it with stock HU from Car manufacturers? Actually i am planning to add mosconi 4to6 or other basic 6 ch dsp with my stock fiat punto stereo made by Harman. If its like that way only then what is a good option to keep stock HU and aiming for SQ Music.
> 
> Stuff which i have as of now:
> Stock player without touch but with 7 band EQ.
> ...




In my experience i had basically a Mosconi 4to6 DSP like what you’re looking at, except mine was built in to the amp (Mosconi D2 100.4DSP) but my factory head unit in my Honda Accord has some eQ that needed to be corrected, i had like a “Cut off or dip” on the lower frequencies so basically I wouldn’t get any bass out of my system so needed to boost the lower frequencies to get a “flat signal output” but since the 4to6 has no input eQ feature to be able to correct that i had to add a JL Audio Fix 82 to correct the Factory HU signal and feed a proper “Flat” signal to DSP before tuning, i later switched to a Mosconi 6to8 that has input eQ so no need for the extra equipment and got rid of the Fix 82. 

With that said, I would take the car to the local Professional shop so they can check the output signal of your Head Unit with an oscilloscope before investing in the 4to6


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## Holmz (Jul 12, 2017)

I have an old HU that predates the special DSP features.
But it has AM, FM, CD, and a couple of Aux inputs.

Even an iPhone has decent output quality, so I am not sure how the sound quality is degraded much through an Aux input. 
There should be some specs for RCA level output in signal to noise and channel seperate on, noise floor, radio sensitivity.
Or as mentioned, maybe have it checked out?

If it has RCA outputs then it may not be as ideal as optical, but they are all generally pretty good.
Isn't it the amps in the head units that usually differ the most? (Which you are not intending on using anyhow)


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## SkizeR (Apr 19, 2011)

sapatel20 said:


> Then DSP is waste if we pair it with stock HU from Car manufacturers? Actually i am planning to add mosconi 4to6 or other basic 6 ch dsp with my stock fiat punto stereo made by Harman. If its like that way only then what is a good option to keep stock HU and aiming for SQ Music.
> 
> Stuff which i have as of now:
> Stock player without touch but with 7 band EQ.
> ...


No. I'm saying a dsp is always worth it

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## Hillbilly SQ (Jan 26, 2007)

OP-I think you'll be fine with the Alpine you already have in your car and something with bells and whistles (like the Pioneer suggested) for your son. Yes some people on here take it to the extreme with Hi-Res but for the average enthusiast I don't see the point. I know some of the people running a Hi-Res unit like the Sony will disagree and that's fine. If I put the same number of hours and expense into my actual install as they have I'd probably run one too. But I doubt most people would be able to honestly tell the difference with the average install with minimal effort (like mine).

Jlugo-tapping into the speaker outputs of a factory headunit can be hit and miss. The sound you get will probably have a "signature" that you can't get rid of. If you can bypass the factory amp to get a clean aftermarket style signal from the factory headunit that should be good enough for 99% of people seeking sq in this hobby. Bypassing my factory amp and getting a clean signal straight from the factory headunit is the best upgrade I'll ever do for my system.


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## Jlugo360 (Mar 6, 2017)

Hillbilly SQ said:


> Jlugo-tapping into the speaker outputs of a factory headunit can be hit and miss. The sound you get will probably have a "signature" that you can't get rid of. If you can bypass the factory amp to get a clean aftermarket style signal from the factory headunit that should be good enough for 99% of people seeking sq in this hobby. Bypassing my factory amp and getting a clean signal straight from the factory headunit is the best upgrade I'll ever do for my system.



Well in my case I didn’t have a factory amp so i can’t talk on that, but that “signature” you’re talking about it was definitely present on mu HU and is sort of what i was referring to when saying that i had a dip on the lower frequencies but after tweaking the input eq on the DSP it was flat on the output channels on RTA, so yeah it could definitely be taken care of, and even in extreme cases like when you have factory time alignment on HU you add a JL Audio Fix and it gets taken care of, i’m not a Pro by any means specially when it comes to tuning but as far as the factory HU integration goes i feel confident when I speak because of what I went through. 

On my first try at the system i did a Audiocontrol LC7i and came back to the shop the next day after install because i had no subwoofer output even with the “Acubass” they gave me a few excuses that didn’t fix my issue, so i took the car to a different shop, where the Pro’s work at and after analyzing the HU output with an oscilloscope the fix was a JL Audio Cleansweep (since the Acubass couldn’t “amplify or boost” a signal that wasn’t being feed to it) the Cleansweep flattened the HU output response, however later on we found out the Cleansweep was introducing distortion when dialing the system in and went with a Fix 82 and then switched to the Mosconi 6to8 Aerospace so yeah its been Real lol.. 

My apologies to the OP if i hi jacked the thread as it wasn’t my intention, just trying to clarify based on my experience



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## Hillbilly SQ (Jan 26, 2007)

Tapping into speaker outputs can and will kill dynamics. You're just amplifying and tuning around a bad (most likely squashed) signal to make it sound as good as possible. But if it sounds good to you that's all that matters.


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## gijoe (Mar 25, 2008)

It looks like some people completely missed the point of your question. 

Does a DSP reduce the need for a sound quality focused head unit? Yes. As long as the source signal is clean you can have a great system after tuning with the DSP. Almost any modern after market stereo will have a clean, low distortion signal that can be fed to a DSP with great results. The cheaper ones might clip earlier, but below clipping you can get a good signal with just about any of them. Modern DACs are very good and even the cheaper won't cause any trouble. With a decent head unit, and a DSP the weak link will be your ability to tune, not the equipment.


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## PPI_GUY (Dec 20, 2007)

elk88 said:


> For reference sake (and off-topic in my own post - haha), I ?_think_? I can class myself as 'old school' with most of my involvement (and gear) being from the 90's (92-2000). This really feels like I'm having a mid-life crisis trying to start this all up again (although I don't intend to compete again and hopefully won't start the merry-go-round of equipment & installs). What this means though is that I'm in way over my head with a lot of this DSP stuff and digital music (my entire music collection is records/tapes for home and CD's for car - haha). If any one is curious, the majority of my gear is still in excellent condition and being brought out of storage for use. Most of what I still have is PPI (PC2150, PC2350, EPX223, 2x DEQ-230), Alpine CDA-7949 w/ tos link changer and a boat load of different speakers/subs that I've used throughout the years (FYI this is not a sales pitch either - I'm not looking to sell anything - my oldest son is almost 16 and when he gets his first car, I'm aiming to set him up with the gear I don't use). My intent is to add a new HU (recommendations welcome), a DSP and since I'll be going with an active crossover set up, a multi-channel amp for the front stage (right now I'm considering the TRU B41-S). I'll likely swap out speakers too (looking at the Hertz Mille line). For what it's worth, I'm just trying to get back to 'that one car'. Doesn't matter how much gear I've been through in the past or setups/ installs I've had in multiple vehicles, there's still that 'one' that stands out among the rest and I'm aiming to get back to it again.


OP, to comment on your off-topic background info, if you decide not to use your old school gear in your own install, you might want to consider letting go of it. NOT TO ME! I have plenty of the older stuff but, old school gear (especially your PC series amps and processors) is bringing solid prices now and you might want to take advantage of the market interest. 
While there is nothing 'wrong' with your gear...in fact it was some of the highest quality back in the day, it is still 20 years old. Your amps are class a/b and as such are inefficient and large. Again, nothing wrong with them (I also own several) but, the same amount of power can be found in quality class D amps that probably take up 1/3 the space and are much easier on your electrical system. Just like component speakers have made tremendous leaps in those 20 years, the same can be said for amps as well. 
I am by no means a pro, guru or anything of the sort. Just wanted to give you something to think about. If you do decide to use your old PPI gear...GREAT! We need more old school PPI fans around here!


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## elk88 (Dec 7, 2012)

gijoe said:


> It looks like some people completely missed the point of your question.
> 
> Does a DSP reduce the need for a sound quality focused head unit? Yes. As long as the source signal is clean you can have a great system after tuning with the DSP. Almost any modern after market stereo will have a clean, low distortion signal that can be fed to a DSP with great results. The cheaper ones might clip earlier, but below clipping you can get a good signal with just about any of them. Modern DACs are very good and even the cheaper won't cause any trouble. With a decent head unit, and a DSP the weak link will be your ability to tune, not the equipment.


This is what I had hoped. I recognize what SkizeR said about distortion/ noise floor but I had been assuming that as long as I was obtaining a strong/clean signal, I could lose a bit of that quality (to get bells/whistles for the kids) and still get what I'm after through the DSP. To be honest; like I implied above, I've been out of it for quite some time and I question if my ears still have the knack to differentiate between those sorts of changes let alone what age and years of competing have done (and as long as I don't fall down the rabbit hole of meets/events/competitions etc, I probably won't know the difference anyway). 

If there aren't any other suggestions made to the contrary of this discussion, I may do as Lycancatt suggests and pick up something like the Pioneer to see how it goes. I'll be sure to scope it to see where it clips etc (yes I still have an oscilloscope and RTA packed in bins with the rest of the gear) and if I'm unhappy with the final results, I may swap back to the Alpine. I just hope that after 17+ years of sitting, the Alpine HU and Changer don't need service (they were fickle even back then). I'm sure I'll figure that out quickly once I put power to them 



PPI_GUY said:


> OP, to comment on your off-topic background info, if you decide not to use your old school gear in your own install, you might want to consider letting go of it. NOT TO ME! I have plenty of the older stuff but, old school gear (especially your PC series amps and processors) is bringing solid prices now and you might want to take advantage of the market interest.
> While there is nothing 'wrong' with your gear...in fact it was some of the highest quality back in the day, it is still 20 years old. Your amps are class a/b and as such are inefficient and large. Again, nothing wrong with them (I also own several) but, the same amount of power can be found in quality class D amps that probably take up 1/3 the space and are much easier on your electrical system. Just like component speakers have made tremendous leaps in those 20 years, the same can be said for amps as well.
> I am by no means a pro, guru or anything of the sort. Just wanted to give you something to think about. If you do decide to use your old PPI gear...GREAT! We need more old school PPI fans around here!


While it cost a fortune at the time, I can't imagine selling my gear even if it's worth a few bucks now (and besides who can pass up on something that doubles as a surf board?). I've yet to hear a Class D amp in action but there's a reason for Class A and A/B being considered SQ amps. That and they were always fantastic workhorses. They're in pristine condition and were never mistreated so as long as they fire up (and I can't imagine why they wouldn't), I can't justify replacing them (I'm sure there's some nostalgia associated with that choice too). I mean yes I'll have to upgrade the alternator/electrical and it looks like folks are using batteries instead of caps but I probably would have done it all anyway regardless of what amps went into the vehicle. That was always one thing I remember clearly. Electrical along with treatment and placement where the paramount factors of an install. Didn't matter what toys you had, tuning you did or fabrication skills you showed off, if you didn't plan and build from a solid foundation, it was a waste of time. Obviously a few things have changed over the years but the principles are still the same. It'll be a fun project for the winter! 

Thanks all!

elk


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## Holmz (Jul 12, 2017)

elk88 said:


> This is what I had hoped. I recognize what SkizeR said about distortion/ noise floor but I had been assuming that as long as I was obtaining a strong/clean signal, I could lose a bit of that quality (to get bells/whistles for the kids) and still get what I'm after through the DSP. To be honest; like I implied above, I've been out of it for quite some time and I question if my ears still have the knack to differentiate between those sorts of changes let alone what age and years of competing have done (and as long as I don't fall down the rabbit hole of meets/events/competitions etc, I probably won't know the difference anyway).
> 
> If there aren't any other suggestions made to the contrary of this discussion, I may do as Lycancatt suggests and pick up something like the Pioneer to see how it goes. I'll be sure to scope it to see where it clips etc (yes I still have an oscilloscope and RTA packed in bins with the rest of the gear) and if I'm unhappy with the final results, I may swap back to the Alpine. I just hope that after 17+ years of sitting, the Alpine HU and Changer don't need service (they were fickle even back then). I'm sure I'll figure that out quickly once I put power to them
> 
> ...


I am pretty sure that HU is as good now and it was back in the day, but you would know if it was good enough in a low level sense - assuming a 600-ohm output drives the headphones - if you could just put an RCA to headphone jack on and test it.

I have some class A/B gear too.
I would not replace it with class-D because it is modern, but for something like a subwoofer where cross-over distortion is not really much of an issue- It makes sense to consider class-D.

And for some tweeter channel, where there is little power needed, then claiming the efficiency benefits of class-D... and the sound is close to class A/B. does not make a compelling reason to give up on the already paid for quality gear. (IMO)


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## ANDRESVELASCO (Dec 7, 2015)

gijoe said:


> It looks like some people completely missed the point of your question.
> 
> Does a DSP reduce the need for a sound quality focused head unit? Yes. As long as the source signal is clean you can have a great system after tuning with the DSP. Almost any modern after market stereo will have a clean, low distortion signal that can be fed to a DSP with great results. The cheaper ones might clip earlier, but below clipping you can get a good signal with just about any of them. Modern DACs are very good and even the cheaper won't cause any trouble. With a decent head unit, and a DSP the weak link will be your ability to tune, not the equipment.


∆∆∆ x2


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## JH1973 (Apr 21, 2017)

I only care about how clean the signal is and where it clips.DSP takes it from there.


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## High Resolution Audio (Sep 12, 2014)

For once I agree with Nick (SkizeR).

I'm old school. I still play CD's, I love class AB amps, and I think some of the best sounding source units (as well as car audio gear in general) were built during the Sound Quality Wars of the 1990's- Early 2000's. 

The whole reason I was dragging my feet about getting a DSP was because I though it might degrade the sound of my Alpine 9835 head unit. But then, thankfully, Leonard Day showed me his Old School Sony head unit with a modern DSP and after I heard it knew I had to get one. 

I ended up with a Helix DSP Pro Mk 2 and Director. 

In my opinion, the source unit is the #1 most important piece of equipment when it comes to designing a SQ system. 

I have heard vehicles with the new head units including the Sony you mentioned, old school head units, and factory head units. 

With my ears and my opinion, systems that used factory head units can sound very good, but are not on par with dedicated SQ head units. 

But I do compete on occasion and my goals may differ from yours.


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## DC/Hertz (Nov 27, 2011)

The only beef I have with my stock HU is it’s noise floor at low volume. If I bypass it’s gone. 
But once it’s playing at listening volume there is nothing I could do differently.


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## ANDRESVELASCO (Dec 7, 2015)

Up to now, my only Head Unit requeriments

1- Flac Reproduction.
2- Rear Usb input (to hide the drive).
3- Basic BT phone functions.

Even a single din with a single RCA pair output is ok for me, as long as it meet these three basic requirements.

From there, I can make any adjutment with my helix director.


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## Truthunter (Jun 15, 2015)

I feel if you can pull a pre-amp signal, either analog or digital, from a factory head unit, then yes it can provide a very good quality base to start with.

BUT, if the only option is to pull a speaker-level signal, then your at the mercy of the factory amplifier's s/n ratio, dynamic range, stereo separation, distortion and volume dependent FR molestation all of which there is no correction for even with the most expensive DSP. AFAIK these attributes become significantly poorer compared to using a pre-amp signal.

For example (not that it's considered high end); the Alpine X008U the I use specs the pre-amp sn ratio 100db but the built-in amp output specs at 85db.

And I have the same experience as Gerald; To my ears there is just something missing in the cars that I've heard that use the factory head unit speaker outputs as a source compared to those that use and aftermarket source. They can be loud and sound better than if there was no post-source aftermarket equipment but, to me, they don't compare to one fed a quality aftermarket source.


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## gumbeelee (Jan 3, 2011)

In my opinion you can not go wrong with a good source. When u have a quality sq head unit, it just makes your dsp sound even better. Thats just my 02 cents


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## ARCuhTEK (Dec 22, 2008)

Lycancatt said:


> and you own one of the better ones in that alpine you listed above, so get your son a pioneer 4200 nex which he'll appreciate the flexibility of and run from there.



FYI. I have the Nex4200 with a Helix DSP Pro set up.... I am no audio expert, but to me the pair sound incredible. I also have never tried to measure my own noise floor, but to my ears, the system seems perfectly quiet when I am not playing music. No whine, no noise at all. I actually really like the 4200 nex.


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## Sine Swept (Sep 3, 2010)

I have an interesting situation. I am using the speaker level outputs from my Kenwood radio as there was an incident with the burning of a certain output transistor on my front RCA outputs. I could have used the other low level output from the radio, but have been using the speaker outs as input into my MS-8. I have listened to it this way for a year or so give or take and could not really give any complaint. 

I do however have a flat output from the radio to the DSP. Although this has never been proven using any scientific approach aside from setting the EQ to flat and no crossovers set. I recall reading somewhere that if you have a low output voltage (low level) that it may sometimes be better to use the hi level outs as it will give you a hotter signal.

Is a flat signal more important than quality components in the radio?


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## drop1 (Jul 26, 2015)

No. A dsp in no way changes the need for a clean source.

If you are talking about all the feature some sq based headunit come with then yes. A dsp will take over crossovers, ta and eq but you will always need a clean, strong source to play the music.


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## Truthunter (Jun 15, 2015)

Sine Swept said:


> I recall reading somewhere that if you have a low output voltage (low level) that it may sometimes be better to use the hi level outs as it will give you a hotter signal.
> 
> Is a flat signal more important than quality components in the radio?


A hotter signal means higher voltage. Speaker level outputs from a head-unit are a higher voltage but higher distortion, lower S/N ratio, and lower stereo separation when compared to low level pre-amp signals.
If the choice was there, I would be use pre-amp output over a head-unit's speaker-level outputs any day.


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## drop1 (Jul 26, 2015)

Truthunter said:


> Sine Swept said:
> 
> 
> > I recall reading somewhere that if you have a low output voltage (low level) that it may sometimes be better to use the hi level outs as it will give you a hotter signal.
> ...


This is true but that's a decision that needs to be made based on everything in the chain behind that source.
Using a dsp then amps to boost that nice clean signal can be worse depending on the equipment.


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## Holmz (Jul 12, 2017)

Truthunter said:


> A hotter signal means higher voltage. Speaker level outputs from a head-unit are a higher voltage but higher distortion, lower S/N ratio, and lower stereo separation when compared to low level pre-amp signals.
> If the choice was there, I would be use pre-amp output over a head-unit's speaker-level outputs any day.


I Agree with the conclusion of using the RCAs, but your "hotter signal" seems a bit misguided.

How can the signal be hotter or cooler than the RCAs if the sound out the speakers is the same? The output impedence of the amp is lower than a line stage. Is that what is called "heat"?

Then whether sound quality is helped by have EQs in the head unit, or whether a pure signal is the definition of quality sort of determines what is a good head unit. Since an iPhone seems as good anything, then the head unit may not matter much if it can supply a clean signal.


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## Truthunter (Jun 15, 2015)

Holmz said:


> I Agree with the conclusion of using the RCAs, but your "hotter signal" seems a bit misguided.
> 
> How can the signal be hotter or cooler than the RCAs if the sound out the speakers is the same? The output impedence of the amp is lower than a line stage. Is that what is called "heat"?


Hotter = higher voltage from the car audio slang I'm familiar with. Speaker level output signals are nominally "hotter" (higher voltage) than pre-amp (RCA) signals.


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## Truthunter (Jun 15, 2015)

drop1 said:


> This is true but that's a decision that needs to be made based on everything in the chain behind that source.
> Using a dsp then amps to boost that nice clean signal can be worse depending on the equipment.


Not following you


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## Holmz (Jul 12, 2017)

Truthunter said:


> Hotter = higher voltage from the car audio slang I'm familiar with. Speaker level output signals are nominally "hotter" (higher voltage) than pre-amp (RCA) signals.



What is the voltage gain of an amplifier? maybe 40:1 ?

More to the point is that one can consider an amplifier more of an impedance matching device.
So you may have 100k-ohms coming in and 4-ohms output impedance.

---
The speaker outputs may be higher voltage when turned up, but if one is bringing in the signal... Then at the same sound level, the voltage through the RCAs would be the same as the voltage through the hotter speakers.

When a speaker is on the amplifier then the back EMF has some distortion. With a purely resistive load it should not be a lot.
I would prefer a class A to drive an RCA when the output impedance does not need to be low...
So yes the RCAs are better, but not because of "heat".
---
Then there is the concept of a "Clean" signal. But I am not sure how unclean, the worst of head units is... The RCAs are usually a lot better than an output amplifier stage - but unless there are specs, I am not sure.


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## Weightless (May 5, 2005)

He's not referring to literal heat. When a signal is louder or of a higher voltage, it is said to be "hotter". Hence the quotes. 

This is common slang in many facets of the audio world.



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## Holmz (Jul 12, 2017)

I get that, but it is no hotter unless the sound is turned up.
If it is at the same level then the "hotness" is equal.

If there is a lot of noise coupled in, then the lower impedance would be better... but that is unusual, and the RCAs should out perform the speaker level outputs.


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## brainbot1 (Feb 19, 2016)

I personally don't feel the need for a head unit anymore. I use my phone as a source like I think most people use these days for daily use.

The only thing that makes me want a head unit is I could keep my steering wheel controls but I really don't mind using my DSP volume knob. the issue with this though is that most headunits dont have digital out (Sony RSX GS9 is an exception but its too expensive for me) so most HU's add a D/A conversion in the signal flow which may degrade sound quality. 

I think its best to keep signal flows as simple as possible so I go digital out from my phone straight to the DSP so there is only one D/A conversion in my signal flow.


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## Carlton9000 (Sep 16, 2017)

brainbot1 said:


> I personally don't feel the need for a head unit anymore. I use my phone as a source like I think most people use these days for daily use.
> 
> The only thing that makes me want a head unit is I could keep my steering wheel controls but I really don't mind using my DSP volume knob


You could use the PAC SWI-X to control the mini DSP units. I used it with great success in a 2008 MX-5 with the mini DSP unit.
https://www.amazon.com/PAC-SWI-X-Universal-Steering-Interface/dp/B0002J22AU


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## Sine Swept (Sep 3, 2010)

The reason the hi-level in is important, is there are OEM integration situations that do not allow for a low level input.

I seem to recall in the article I read about using HI over LO, was in a situation where the radio is junk and less than 1.5 volt preout. Which would never happen in a situation with a really nice source unit.

How do we measure the source to prove one radio is better than another?


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## Holmz (Jul 12, 2017)

Sine Swept said:


> The reason the hi-level in is important, is there are OEM integration situations that do not allow for a low level input.
> 
> I seem to recall in the article I read about using HI over LO, was in a situation where the radio is junk and less than 1.5 volt preout. Which would never happen in a situation with a really nice source unit.
> 
> How do we measure the source to prove one radio is better than another?


Many good radios are 1v pre outs, which would not be called "junk".

What are you trying to show?
Noise floor is one measurement, and there is cross talk, and SNR or some THN plus distortion.

Having a way to measure it allows one to assert that it is/isn't junk.


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## brainbot1 (Feb 19, 2016)

Carlton9000 said:


> You could use the PAC SWI-X to control the mini DSP units. I used it with great success in a 2008 MX-5 with the mini DSP unit.
> https://www.amazon.com/PAC-SWI-X-Universal-Steering-Interface/dp/B0002J22AU


Thanks for this! something to keep in mind. So this uses IR? Can you set it up to do presets 1-4 and mute in addition to volume control?


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## Carlton9000 (Sep 16, 2017)

brainbot1 said:


> Thanks for this! something to keep in mind. So this uses IR? Can you set it up to do presets 1-4 and mute in addition to volume control?


It has been a while since I used it. But I was running a headless setup with just the iPhone as a source with the mini dip and I was able to control volume, tracking, play/pause, and hands free on the phone. Here is a link to the build:

http://www.thecarversite.com/yetanotherforum/default.aspx?g=posts&t=8008


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## DarmoZ (May 20, 2016)

brainbot1 said:


> I personally don't feel the need for a head unit anymore. I use my phone as a source like I think most people use these days for daily use.
> 
> The only thing that makes me want a head unit is I could keep my steering wheel controls but I really don't mind using my DSP volume knob. the issue with this though is that most headunits dont have digital out (Sony RSX GS9 is an exception but its too expensive for me) so most HU's add a D/A conversion in the signal flow which may degrade sound quality.
> 
> I think its best to keep signal flows as simple as possible so I go digital out from my phone straight to the DSP so there is only one D/A conversion in my signal flow.


Finally a post that makes sense to me. I don't understand why this isn't becoming the standard now and companies are not making units that meet today's requirements (your music library digitally in in Spotify/Apple music/Tidal). It's 2018, and i know high level input from a source has always been viewed inferior, but in my eyes low level RCA input should also be viewed inferior. 

In my mind the perfect solution is this (and i don't know if this is on the market yet already, but as far as i can see it isn't which is stupid) 

A Head Unit & DSP (let's call it a HUDSP) built into one single/double din size unit, that can accept your iPhone via USB input. This way the HUDSP is taking the digital file directly off the iphone when using Apple music/Tidal/Spotify (same as plugging a memory stick into the unit with a flac/mp3 file on it), performs the DAC once, then the processing, and off the signal goes to the amps.

Why on god's green earth is this not a product yet????


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## gijoe (Mar 25, 2008)

DarmoZ said:


> Finally a post that makes sense to me. I don't understand why this isn't becoming the standard now and companies are not making units that meet today's requirements (your music library digitally in in Spotify/Apple music/Tidal). It's 2018, and i know high level input from a source has always been viewed inferior, but in my eyes low level RCA input should also be viewed inferior.
> 
> In my mind the perfect solution is this (and i don't know if this is on the market yet already, but as far as i can see it isn't which is stupid)
> 
> ...


There are plenty of head units that also have DSP. The reason you aren't seeing a lot of new ones is because people aren't replacing head units like they used to.


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## DarmoZ (May 20, 2016)

I'm sure in the market for a new one. My Alpine 178bt sounds **** when iphone plugged directly into it, especially high notes sounds very harsh, its not the amp/speaker fault as it's a Hertz HDP4 going into Mille Legends, i suspect it's a jitter of the head unit DAC. If i plug the iphone 6 in via Aux (using the iphone DAC) the music is more enjoyable and natural sounding, harshness of the high notes go away, but of course with the Aux you have to accept a little bit of noise. 

This must mean that the DAC in a 2013 'Audiophile' head unit, is not as good as the one that comes in a 2014 iphone.


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## DarmoZ (May 20, 2016)

brainbot1 said:


> I think its best to keep signal flows as simple as possible so I go digital out from my phone straight to the DSP so there is only one D/A conversion in my signal flow.


How do you digital out from the phone directly into the DSP, what phone / DSP are you using?

i use iphone, so do i have to buy a DSP that has the 'made for iphone' badge on it? so that it can be plugged in to the DSP directly via the USB cable?


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## gijoe (Mar 25, 2008)

DarmoZ said:


> I'm sure in the market for a new one. My Alpine 178bt sounds **** when iphone plugged directly into it, especially high notes sounds very harsh, its not the amp/speaker fault as it's a Hertz HDP4 going into Mille Legends, i suspect it's a jitter of the head unit DAC. If i plug the iphone 6 in via Aux (using the iphone DAC) the music is more enjoyable and natural sounding, harshness of the high notes go away, but of course with the Aux you have to accept a little bit of noise.
> 
> This must mean that the DAC in a 2013 'Audiophile' head unit, is not as good as the one that comes in a 2014 iphone.


Based on Alpines reputation, I find it difficult to believe that one of their top head units suffers from sounding "like ****." I suspect your problem lies in the settings, or maybe you have a defective unit, and just because they are Mille Legends doesn't mean they can't sound harsh, are they run actively, or passively?


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## brainbot1 (Feb 19, 2016)

DarmoZ said:


> How do you digital out from the phone directly into the DSP, what phone / DSP are you using?
> 
> i use iphone, so do i have to buy a DSP that has the 'made for iphone' badge on it? so that it can be plugged in to the DSP directly via the USB cable?


Galaxy S8 and Iphone6 and higher. I use the S8 and my girl uses an iphone6. It was the biggest reason I upgraded S7 to S8. And with a USB-C splitter I can charge my phone whilst digital audio out with a self powered USB to SPDIF converter to the SPDIF input of the miniDSP  

https://www.amazon.com/gp/product/B01M3NOFXQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


https://www.amazon.com/gp/product/B0093KZTEA/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

and this is the transformer I use on the Dirac unit 
https://www.amazon.com/DROK-Converter-Step-down-Transformer-Waterproof/dp/B00CEP3A0Q?th=1


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## DarmoZ (May 20, 2016)

gijoe said:


> Based on Alpines reputation, I find it difficult to believe that one of their top head units suffers from sounding "like ****." I suspect your problem lies in the settings, or maybe you have a defective unit, and just because they are Mille Legends doesn't mean they can't sound harsh, are they run actively, or passively?


It's actually my second unit, and i didn't enjoy it just like the first one, so doubt i had two defective units in a row. Been through all the settings, kept the MX off, EQ on flat, used HU Xovers, then used Amp Xovers, tried defeat mode aswell, still can't get the sound i'm after, don't me wrong i can play loud and clean, but i feel like the different notes of the music are off timed, which is why i'm thinking jitter. 

The front comp's are with the passive crossover. Amp in bridged mode (as per the manual for component sets) it's giving 500w to each side. Iv'e set gains using a multimeter, however to get the loudest and cleanest sound best to leave the amp gains on lowest point, this way i can crank the HU all the way to 35. It get's loud and clean don't get me wrong, but i just don't find my self tapping away to the music and getting into the music for some reason. With the iphone in via Aux i do more.

It's funny cos in my old car i use the 173-bt HU powering the speakers, active halfords sub in the boot and it sounded great for many years, which is why i went with alpine again for my high end build. 

Hell it could be spotify app, could be the speaker install (although was done by a pro shop) May ditch the Hertz for pioneer high end, as i had pioneer mid range in the old car and loved them.


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## DarmoZ (May 20, 2016)

brainbot1 said:


> Galaxy S8 and Iphone6 and higher. I use the S8 and my girl uses an iphone6. It was the biggest reason I upgraded S7 to S8. And with a USB-C splitter I can charge my phone whilst digital audio out with a self powered USB to SPDIF converter to the SPDIF input of the miniDSP
> 
> https://www.amazon.com/gp/product/B01M3NOFXQ/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
> 
> ...


Sounds good, the Muse USB to Optical works with iphone then?


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## brainbot1 (Feb 19, 2016)

DarmoZ said:


> Sounds good, the Muse USB to Optical works with iphone then?


Yes, just get the lightning camera adapter from apple. 

Sent from my SM-G950U using Tapatalk


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## DarmoZ (May 20, 2016)

brainbot1 said:


> Yes, just get the lightning camera adapter from apple.
> 
> Sent from my SM-G950U using Tapatalk


Awesome, Thanks! didn't realise i could do this......bye bye head unit!

I may ask on the forum first though for an even simpler solution.....a DSP that is 'made for iphone' so i can just simply plug the iphone directly into the DSP with the cable provided by apple. That's the product i'm really waiting for, then i can have ipad mini in dash and use that as my permanent in car head unit.


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## brainbot1 (Feb 19, 2016)

DarmoZ said:


> Awesome, Thanks! didn't realise i could do this......bye bye head unit!
> 
> I may ask on the forum first though for an even simpler solution.....a DSP that is 'made for iphone' so i can just simply plug the iphone directly into the DSP with the cable provided by apple. That's the product i'm really waiting for, then i can have ipad mini in dash and use that as my permanent in car head unit.


You could wait or you can do a permanent install with the info I provided. Like I said before, it charges and does digital audio out. I also plan on eventually doing a permanent iPad install just so my setup is completely wireless in appearance but I like being able to navigate on my phone. 

Sent from my SM-G950U using Tapatalk


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## audiocholic (Dec 5, 2016)

Jlugo360 said:


> In my experience i had basically a Mosconi 4to6 DSP like what you’re looking at, except mine was built in to the amp (Mosconi D2 100.4DSP) but my factory head unit in my Honda Accord has some eQ that needed to be corrected, i had like a “Cut off or dip” on the lower frequencies so basically I wouldn’t get any bass out of my system so needed to boost the lower frequencies to get a “flat signal output” but since the 4to6 has no input eQ feature to be able to correct that i had to add a JL Audio Fix 82 to correct the Factory HU signal and feed a proper “Flat” signal to DSP before tuning, i later switched to a Mosconi 6to8 that has input eQ so no need for the extra equipment and got rid of the Fix 82.
> 
> With that said, I would take the car to the local Professional shop so they can check the output signal of your Head Unit with an oscilloscope before investing in the 4to6
> 
> ...



as most OEM HU I expect my Head unit wouldnt be giving the flattest of all signals either.


In this case can I solve this by simply compensating with the EQ from DSP output on the 4to6? 



its obvious there is a benefit to being able to eq on the input side also since its added to the higher tier units but how bad is it really to eq on whats available (4to6 in my case) and I truely ask cause I do not know no smart ass question or sarcasm that I see alot here


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## Jlugo360 (Mar 6, 2017)

4to6 doesn’t have input eQ i had to purchase a JL Audio Fix82 to go into my Mosconi D2 100.4 DSP which basically has a 4to6 built into it, and a few months later got a 6to8 Aerospace so removed the other equipment being that 6to8 has the input eq....

All the mentioned equipment is for sale now if interested look at my post’s for the sale thread....


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## audiocholic (Dec 5, 2016)

Jlugo360 said:


> 4to6 doesn’t have input eQ i had to purchase a JL Audio Fix82 to go into my Mosconi D2 100.4 DSP which basically has a 4to6 built into it, and a few months later got a 6to8 Aerospace so removed the other equipment being that 6to8 has the input eq....
> 
> All the mentioned equipment is for sale now if interested look at my post’s for the sale thread....


thanks mate for replying,



but to be honest I understand the 4to6 doesnt have input eq, what I want to understand how bad it is to simply eq the output signal rather than doing it before entering the dsp via input eq?


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## Jlugo360 (Mar 6, 2017)

Ok, my mistake...
Now I understand the question, i had asked the same thing to my installer before purchasing new equipment and i was told that in my case the factory Head Unit had a bass rolloff at 80hz so there was “no way to tune something that isn’t there” so i guess it would depend on what you’ve got going on with your Head Unit


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## elijahscott (Jun 23, 2017)

How many more people are running headless with their phones or iPads? I’ve been doing it for a few years now with my dm810 AudioControl dsp, running one digital coax to the dsp from this mini dac ( https://www.parts-express.com/smsl-x-usb-dac-digital-audio-interface-with-dsd-support--230-236?gclid=EAIaIQobChMIi-Ch6KWA5gIVghh9Ch24UwSJEAQYASABEgLRjvD_BwE ). Then I used a usb camera kit for my iPhone to get power to the phone and also using a usb y cable to get power to the dac. With this there is no noise floor like I get from my factory head unit(audi a4). I could never get the noise floor gone with the factory 
head unit and I need the computer stuff integrated into the car so I can’t get rid of it. 
It’s been a little while since the last post so I’d assume more people are doing this now?
My only question is with an iPhone as the source wouldn’t the input v be .9 or so? Isn’t that too low? Would I need a line driver or is that what my dsp is doing?


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