Premium Audio - In depth
Discussion
OK, slow day! 
I thought I would drag out the test gear and have a look at the Premium Audio and see what is what.
Now normally when setting up high end audio, I would set everything flat, center the gains and level the attenuation. Get the RTA out and set up one channel at a time, then run the full system and fine tune. Last of all, listen and alter to taste.
The Alpine system in the AM cant do any of this. The eq changes both channels at once and there are no separate gain controls for each driver. Whatever comes out, its going to be a compromise.
OK, lets start by evaluating.
The significant drivers in the system are the front door speakers and the sub. The door speakers consist of a 4" mid and tweet. already this isn't good. The 4" isn't going to go nearly low enough to bridge the gap to the sub. That means either we will have a hole in the frequency response, distortion from exceeding its response limits or the sub will drag the soundstage back by working at higher frequencies to make up for the lack of punch in the 4".
Subs come in a variety of forms. Sealed units have great tonal balance and are very musical, but lack power so invariably are hard driven big linear units. Ported designs have the advantage of making more bass in small space. From a tonal balance point of view, ported boxes have a tendency to be 'one note' as they are tuned to the frequency of the port rather than balanced over a wide range. I suppose its all conjecture until we check.
The image below is the flat response of the system using a spectrum analyser at 1/48 octave resolution with a calibrated mic. I've averaged a few thousand samples to get the curves. Mic position was from the drivers, passenger and center location to get spacial averaging.
What we see is a resonance from the subwoofer and a hole in the mid-bass at 150hz and 500-800hz. A peak at 1k and another hole at 10k. Higher than this appears to be the tweeters roll off.
The tweet roll off is not a bad thing. Ribbons and some metal domes can minimise this but end up sounding harsh. I dont think the Alpine tweeter is harsh, but could be better. There's nothing like the sound of a nice 1 or 2" silk dome. A lack of >10k signal can lead to a loss of spacial awareness and sibilance.
The hole at 10k is unusual, running an active signal sweep into the system would help but I couldn't be arsed to link it in to find out. High energy at this frequency point just hurts anyway. Lets reserve judgement of it being a problem for now.
The mid bass holes are the ones that will need looking at. The 150-250Hz range is great for giving a string section a fuller sound. Listen to The Beatles 'Eleanor Rigby' and The Rolling Stones' 'As Tears Go By' and you'll know what I mean. A lack of energy in this department also, and most important for me, will render drums without sufficient energy and seem gutless. This frequency is fundamental for snare, toms, guitars and male vocals. With the peak at 6k, would have given great attack
.
Since the flaw in apparent in both speakers when played independently, I would conclude its either the drivers limitation or in combination with door skin resonances and reflections off the interior.
Then there is the sub. It clearly shows a resonance and a sharp roll off at 80hz. I think that's as high as they could go for the crossover before making it too obvious and dragging the stage backwards.
Test tracks also threw up some anomalies such as phase changes. Normally when drivers are out of phase, they sound diffused and difficult to locate in the soundstage. In the case of the AM Dolby, out of phase just produced sound out of the rear. There's another tool gone from the box!!
My advise would be to leave Dolby off if you are a purist. The downside is you will lose the center channel speaker. As the door speakers are positioned with unequal path lengths, the center is a good cheat to good imagery. So, compromise.
Lets leave it on and turn the rear down, right down.
OK, on to corrections.
What we want to achieve is a nice smooth response. We do not want a flat line, far from it. Our target is a nice downsloping line from about 250Hz to 10-20kHz at a rate of 1-1.7db/octave.
There will invariably be some peaks/valleys in the response that are caused by reflections and other sources. If that's the case then no matter how much you equalise, it will make no difference to the actual frequency response. Unless you are considering moving the speakers, live with them.
Here is the end result of a lot of fannying around and adjusting this, that and the other. This is what we call a 'point of reference' sound for accuracy. The sound can be modified by some bass enhancement but this would only improve the punch by adding sub output rather than filling the massive gap in the frequency response. To modify, I suggest using the bass & treble rather than the eq. It will keep it smoother.
Balance is set from SPL readings on pink noise then verified from a reference soundstage recording. Imagery is above average.
Subwoofer setting ensures the bass appears to come from the front, as you increase the subs output, it becomes more apparent where it is. The sub has plenty to keep anyone happy.
The good thing about this setup, is the quick bass/treble settings are flat. so when you get different recordings, you can alter them on the fly and put it back to flat.
All I can say is the most annoying thing is no track repeat for the reference track. I can't tell you how frustrating it is when you've gone through a dozen mic points, different settings and when your nearly there, it goes to the next track.... Grrrrrrr
Concluding, it will be really easy to improve on the Premium Audio option. Increasing the size of the midbass would yield the largest improvement by getting rid of the 150hz hole. Even a 5 1/4" driver would make a massive difference. I think they could be made to fit. The sub crossover is too high in my opinion, a compromise made as the mid driver is pretty useless.
I'm so temped to fit a custom mount with some 5 1/4" mids.
Personally, there won't be that many times where I'll be listening to the stereo and care enough about the sound that much.
Settings-
Balance - 2/3 clicks to the left
Fader - 4 clicks or all the way forward
Surround - 4 clicks down
EQ-
60hz - down 1
200hz - up 1
1k - down 2
3k - up 2
12k - zero
Bass & treble - zero
Subwoofer - 1 click down
I thought I would drag out the test gear and have a look at the Premium Audio and see what is what.
Now normally when setting up high end audio, I would set everything flat, center the gains and level the attenuation. Get the RTA out and set up one channel at a time, then run the full system and fine tune. Last of all, listen and alter to taste.
The Alpine system in the AM cant do any of this. The eq changes both channels at once and there are no separate gain controls for each driver. Whatever comes out, its going to be a compromise.
OK, lets start by evaluating.
The significant drivers in the system are the front door speakers and the sub. The door speakers consist of a 4" mid and tweet. already this isn't good. The 4" isn't going to go nearly low enough to bridge the gap to the sub. That means either we will have a hole in the frequency response, distortion from exceeding its response limits or the sub will drag the soundstage back by working at higher frequencies to make up for the lack of punch in the 4".
Subs come in a variety of forms. Sealed units have great tonal balance and are very musical, but lack power so invariably are hard driven big linear units. Ported designs have the advantage of making more bass in small space. From a tonal balance point of view, ported boxes have a tendency to be 'one note' as they are tuned to the frequency of the port rather than balanced over a wide range. I suppose its all conjecture until we check.
The image below is the flat response of the system using a spectrum analyser at 1/48 octave resolution with a calibrated mic. I've averaged a few thousand samples to get the curves. Mic position was from the drivers, passenger and center location to get spacial averaging.
What we see is a resonance from the subwoofer and a hole in the mid-bass at 150hz and 500-800hz. A peak at 1k and another hole at 10k. Higher than this appears to be the tweeters roll off.
The tweet roll off is not a bad thing. Ribbons and some metal domes can minimise this but end up sounding harsh. I dont think the Alpine tweeter is harsh, but could be better. There's nothing like the sound of a nice 1 or 2" silk dome. A lack of >10k signal can lead to a loss of spacial awareness and sibilance.
The hole at 10k is unusual, running an active signal sweep into the system would help but I couldn't be arsed to link it in to find out. High energy at this frequency point just hurts anyway. Lets reserve judgement of it being a problem for now.
The mid bass holes are the ones that will need looking at. The 150-250Hz range is great for giving a string section a fuller sound. Listen to The Beatles 'Eleanor Rigby' and The Rolling Stones' 'As Tears Go By' and you'll know what I mean. A lack of energy in this department also, and most important for me, will render drums without sufficient energy and seem gutless. This frequency is fundamental for snare, toms, guitars and male vocals. With the peak at 6k, would have given great attack
. Since the flaw in apparent in both speakers when played independently, I would conclude its either the drivers limitation or in combination with door skin resonances and reflections off the interior.
Then there is the sub. It clearly shows a resonance and a sharp roll off at 80hz. I think that's as high as they could go for the crossover before making it too obvious and dragging the stage backwards.
Test tracks also threw up some anomalies such as phase changes. Normally when drivers are out of phase, they sound diffused and difficult to locate in the soundstage. In the case of the AM Dolby, out of phase just produced sound out of the rear. There's another tool gone from the box!!
My advise would be to leave Dolby off if you are a purist. The downside is you will lose the center channel speaker. As the door speakers are positioned with unequal path lengths, the center is a good cheat to good imagery. So, compromise.
Lets leave it on and turn the rear down, right down.
OK, on to corrections.
What we want to achieve is a nice smooth response. We do not want a flat line, far from it. Our target is a nice downsloping line from about 250Hz to 10-20kHz at a rate of 1-1.7db/octave.
There will invariably be some peaks/valleys in the response that are caused by reflections and other sources. If that's the case then no matter how much you equalise, it will make no difference to the actual frequency response. Unless you are considering moving the speakers, live with them.
Here is the end result of a lot of fannying around and adjusting this, that and the other. This is what we call a 'point of reference' sound for accuracy. The sound can be modified by some bass enhancement but this would only improve the punch by adding sub output rather than filling the massive gap in the frequency response. To modify, I suggest using the bass & treble rather than the eq. It will keep it smoother.
Balance is set from SPL readings on pink noise then verified from a reference soundstage recording. Imagery is above average.
Subwoofer setting ensures the bass appears to come from the front, as you increase the subs output, it becomes more apparent where it is. The sub has plenty to keep anyone happy.
The good thing about this setup, is the quick bass/treble settings are flat. so when you get different recordings, you can alter them on the fly and put it back to flat.
All I can say is the most annoying thing is no track repeat for the reference track. I can't tell you how frustrating it is when you've gone through a dozen mic points, different settings and when your nearly there, it goes to the next track.... Grrrrrrr
Concluding, it will be really easy to improve on the Premium Audio option. Increasing the size of the midbass would yield the largest improvement by getting rid of the 150hz hole. Even a 5 1/4" driver would make a massive difference. I think they could be made to fit. The sub crossover is too high in my opinion, a compromise made as the mid driver is pretty useless.
I'm so temped to fit a custom mount with some 5 1/4" mids.
Personally, there won't be that many times where I'll be listening to the stereo and care enough about the sound that much.
Settings-
Balance - 2/3 clicks to the left
Fader - 4 clicks or all the way forward
Surround - 4 clicks down
EQ-
60hz - down 1
200hz - up 1
1k - down 2
3k - up 2
12k - zero
Bass & treble - zero
Subwoofer - 1 click down
If you download both images and flick from one to the other, its pretty telling!!
Everything is subjective in sound settings except the bl00dy big holes in the frequency response. Until you fix that, its all a matter of choice.
This is why I put the frequency curves up. At least you can see where your starting from.
I use the IASCA judging disc, a throwback from when I used to be on the circuit. If your really into your music, its worth having in the toolbox.
Don't forget that this is static. When you're driving the road noise will suck the life out of your bass.
Everything is subjective in sound settings except the bl00dy big holes in the frequency response. Until you fix that, its all a matter of choice.
This is why I put the frequency curves up. At least you can see where your starting from.
I use the IASCA judging disc, a throwback from when I used to be on the circuit. If your really into your music, its worth having in the toolbox.
Don't forget that this is static. When you're driving the road noise will suck the life out of your bass.
Edited by divetheworld on Sunday 10th March 21:13
Edited by divetheworld on Sunday 10th March 21:28
WeirdNeville said:
You've got nearly a 6bd gain in the dips there - was that by massaging curves up or pulling surrounding frequencies down?
Some of it was blind luck I reckon. The Q of the eq is that wide that it makes it hard to make any meaningful fix.Shifting the balance and fader/surround might be a factor.
Jon39 said:
Thank you Brent, for your interesting article.
My question is, do you keep your suggested settings unaltered for different types of music, eg. 'Living Daylights', 'Balade pour Adeline', and 'It's Still Rock & Roll To Me'?
If there should be an adjustment to play either melodic, classical, or rock (with it's heavier bass), what changes would you suggest?
My question is, do you keep your suggested settings unaltered for different types of music, eg. 'Living Daylights', 'Balade pour Adeline', and 'It's Still Rock & Roll To Me'?
If there should be an adjustment to play either melodic, classical, or rock (with it's heavier bass), what changes would you suggest?
djmac56 said:
As a result of mp3 compression, some studios are remastering to allow for people listening through headphones rather than a a pair of wharfdales, kef's etc. But what does this mean for our car settings? Do we need to up the bass and treble to compensate for mp3 compression?
All recordings and music sources are different. When you have a well sorted system, you get paranoid when something sounds crap. I like to think that if I have the system as good as it can be then when something doesnt sound right, I know its the track and not the system. That's why I set the eq for reference and use the bass and treble controls to alter to suit the mood/track/beat.
Instead of trying to second guess your music, try setting up or listening to your system with a reference track. Some naughty people have posted up a download link below.
I always use original discs BTW!
Alternatively, try Sheffield Labs discs like this one -
http://www.sheffieldlab.com/sheffield.pl?category=...
https://itunes.apple.com/album/id254821041
http://www.diymobileaudio.com/forum/technical-adva...
http://fs10n3.sendspace.com/dl/11ecceb3e9ab89f8003...
Edited by divetheworld on Monday 11th March 17:47
montecristo said:
Very interesting. I am curious as to why you change the balance - doesn't that mean the music will be distorted for the passenger, as her (hopefully) nearside speakers are now too loud?
Its about imagery. The driver should be able to close his/her eyes and picture a uniform soundstage. With the speakers being so poorly positioned, the path lengths from each driver are so different that the image will be skewed. Without time alignment, someone will have a poor image. Better the passenger than the driver.Wanna see how bad a car is? Cut this to disc and play. The 7 drums are equidistant on the soundstage.
http://www.puwer.co.uk/uploads/Imaging.mp3
Gassing Station | Aston Martin | Top of Page | What's New | My Stuff