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what differs sql and spl


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ice32 
Copper - Posts: 116
Copper spacespace
Joined: June 12, 2007
Location: Australia
Posted: November 18, 2007 at 2:53 AM / IP Logged  
Thanks for the clarification, just always read ppl say choose eather SPL or SQ just curious as to how the systems are setup different to excel in the selected area
haemphyst 
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Posted: November 18, 2007 at 10:39 AM / IP Logged  
djdowdell wrote:
I will try my best to clarify and if I miss anything guys chime in. Difference with spl(sound pressure level) and sql (sound quality level) is mostly system design.
First of all, there is NO SUCH OFFICIAL TERM AS SQL. Try to find one, anywhere. You won't. Why? Because it's a nonsense phrase. I typed "what is sql" into a search engine, and this was the result of that search...
djdowdell wrote:
Lets start with spl. SPL mainly deals with subs b/c low frequencies produce the most sound pressure. You need lots of power to get high SPL. So you may need multiple batteries and/or multiple and/or high output alternators to supply the power and lots of wire to carry it.
No... No... No...
1: Sound pressure is EQUAL, across the entire audio bandwidth, unless the system is DESIGNED to make, with great efficiency, a narrow band of audio, like in the subwoofer band. There are MANY ways to produce high SPL numbers, and lots of power is only ONE WAY. Multiple woofers and enclosure are the other two major ways. Lots of power and multiple woofers is commonplace today, but it's NOT the only way.
2: High frequencies can be made to get JUST as loud as subwoofers, and will oftentimes require ORDERS OF MAGNITUDE less power. The overall efficiency of the driver has a tremendous effect on the overall output capabilities of a given driver. A driver with a 100dB efficiency (not common, but they DO exist, and they are generally high-frequency drivers) will only take 9 watts to acheive 128dB output, but a driver with an efficiency rating of 85dB (typical in today's world of long-throw, extreme power woofers) will require as much as 16 THOUSAND watts to do the same output. (I am referring to anechoic responses. I cannot (and nobody CAN) tell you, how much power is required in a car. I can tell you as can ANYBODY, that it is far less than an anechoic response, due to the addition of cabin gain.)
Your generalizations are (as all generalizations are...) FALSE.
djdowdell wrote:
As far as the head unit is concerned you may need one with high voltage output on the rca's, and a good sampling rate(?) to help combat skipping caused by vibrations unless u isolate outside the vehicle.
False, again, as you can make ANY amplifier accept even a 200mV input and produce maximum power, and maximum power is the the desired result. You do NOT have to have a high voltage RCA, but you DO have to match your amplifier's INPUT requirements with/to the available RCA voltage. Hmmm... could that be a little thing called a GAIN CONTROL? Stick with me here... It gets better.
and 2: Skipping or not skipping has nothing (as in zero, none, nada, niente, and in no way, shape or form) to do with sampling rate, or RCA voltage. Here's the big serach I did, and here's a Wiki entry, regarding "sampling rate"...
djdowdell wrote:
Speaking of vibrations you MAY have to go to such extremes as concrete for sound damping again depending on your goals, sanctioning body etc.
I'll let that go... pretty much true, EXCEPT for the fact that it's not required for SPL.
djdowdell wrote:
Your amps ideally should have a high voltage rating or high current and be class D again b/c of efficiency.
EEEEEENNNNNNHHHHHH! Again, wrong answer. Again, it will all depend on the topography (the design, if you will) of the amplifier. You can get JUST as much output from any given Class A/B amplifier as you can from an equally powered Class D amp. Higher efficency has nothing, again, to do with overall output. The efficiency of an amplifier ONLY determines how much of the input power actually goes out to the drivers, i.e. how much heat will the amplifier make. It's only a number that determines overall waste in the system.
djdowdell wrote:
Subs are really the only major concern and should be matched with the amps (as all speakers should be) and a properly designed enclosure(s) with port tuned to the resonant frequency of the vehicle to maximize SPL. Now granted it will not be "musical" but hey all you want is pressure.
This, I'll agree with... there are several schools of thought, but I'm pretty much of this school.
djdowdell wrote:
Now sound quality is another beast all together. I left out level because sound quality is like beauty, its subjective but most have a general consensus on what sounds good. Sound pressure is measured scientifically with no ifs ands or buts about it.
You left out "level" because it's correct to leave it out. Please see my opening rebuttal line. You are also correct to a certain extent in the respect the SQ is subjective, but in the sanctioning of SQ contests, there are very hard and fast rules to judging that, just as there are in SPL competitions. It's a little thing called "Frequency Response". It is desired (if not REQUIRED) to be as flat as possible, "no ifs, ands, or buts". Also quite scientific. There are many other things that are scientifically judged as well, but you are largely correct in the "subjective" part of SQ.
djdowdell wrote:
Now sound quality u may or may not have to upgrade alternators depending on your class if you compete. It also doesnt have to a large complicated system. Some of the best systems have the fewest speakers.
Mostly true. I recommend upgrading the alternator in ANY system, no matter HOW small or what it's application. If you add an amplifier, you will add an alternator.
djdowdell wrote:
Now with sound quality (man, what did i get myself into) is really complicated. U still need high voltage output for a good clean signal but a lot more comes into play like the quality of a/d converters and such. Almost all the specs, THD and frequency reproduction range, etc. come into play.
But it's not scientific, and no hard rules. what differs sql and spl - Page 2 -- posted image. Again, you don't have to have high voltage on the signal leads. ANY pre-amp output section can be made to perform as well as any OTHER pre-amp output section, whether the output voltage is 150mV or 16V balanced. Proper matching and care with installation is FAR more important than a "high RCA voltage".
djdowdell wrote:
Not to mention now u have to use a/b class amps for the midrange/tweeters (unless you can find tubes).
Another wrong answer, Seabee! Some of the FINEST sounding amplifiers in the WORLD are Class D. Spectron comes to mind... Here's the reviews... Bang & Olufsen ICEPower amplifiers are consistently praised as some of the finest sounding amplifiers around, and were at one time called "The Perfect Amplifier". Jeff Rowland embraces PROUDLY ICEPower. All Class D. Alpine (in the PDX amplifier line) and Eclipse (in the XA series amplifiers) both use ICEPower modules. No... It is no longer true that you must use analog amplification for true sound quality.
djdowdell wrote:
Also speakers need to be sensitivity matched, crossedover at the right point, positioned for stage height, depth, time aligned, etc. And a bunch of other stuff. Then u gotta consider matching subwoofer size and wattage with the other speakers so u can have a perfect frequency balance. A sealed enclosure is ideal for woofer control. Way too much to list. But for a decent everyday non competition system I say get quality equipment, a five channel amp with 300 watts for the sub and 200watts split between the other four speakers and your good. Sorry I cant get in more depth but its 3:30A where I am and I'm sleepy. Sorry for any omissions or mistakes. Help guys.
Mostly right, except for the power ratings. You DID say for an everyday driver, though, so I'll agree with this paragraph. For a true SQ competition class system, those front stage ratings are about 1/4 what they need to be... Headroom is our friend, and is mandatory for perfect performance.
I'm really sorry to tear into it like that, but WOW, that was a lot of mis-information.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
djdowdell 
Copper - Posts: 60
Copper spacespace
Joined: December 07, 2005
Location: Kentucky, United States
Posted: November 18, 2007 at 2:06 PM / IP Logged  

Ha I love haemphyst! Well let me explain a little about my "false generalizations" if I may. First and foremost I never said that this was concrete. Acoustic theory is much to deep to get into in a forum number one. Number two, I think the question was a general one not a scientific one. As far as acoustic theory goes my generalizations were not completely accurate (i.e. concrete) but for the purposes of the question I just used competitions because Im pretty sure thats what the question was pertaining to that.what differs sql and spl - Page 2 -- posted image.

"NO SUCH OFFICIAL TERM AS SQL." This is something I know already I just used as a reference to the question. And SQL is actually sound quality league in MECA.

"1: Sound pressure is EQUAL, across the entire audio bandwidth, unless the system is DESIGNED to make, with great efficiency, a narrow band of audio, like in the subwoofer band. " That is why I said subwoofers, reference my competition statement. I've never seen an Sound Pressure vehicle full of tweeters. Not saying it aint possible but my answer is not a scientific one, just whats done majority of the time.

"There are MANY ways to produce high SPL numbers, and lots of power is only ONE WAY. Multiple woofers and enclosure are the other two major ways. Lots of power and multiple woofers is commonplace today, but it's NOT the only way. " Thanks, I left that part out.what differs sql and spl - Page 2 -- posted image.

"2: High frequencies can be made to get JUST as loud as subwoofers, and will oftentimes require ORDERS OF MAGNITUDE less power. The overall efficiency of the driver has a tremendous effect on the overall output capabilities of a given driver. A driver with a 100dB efficiency (not common, but they DO exist, and they are generally high-frequency drivers) will only take 9 watts to acheive 128dB output, but a driver with an efficiency rating of 85dB (typical in today's world of long-throw, extreme power woofers) will require as much as 16 THOUSAND watts to do the same output. (I am referring to anechoic responses. I cannot (and nobody CAN) tell you, how much power is required in a car. I can tell you as can ANYBODY, that it is far less than an anechoic response, due to the addition of cabin gain.) " Absolutely true but people compete in spl not just for scientific numbers but fun. I dont think a high frequency driver has as much of a fun, crowd pleasing factor as a low frequency transducer, hence my reference only included subwoofers.
 
"False, again, as you can make ANY amplifier accept even a 200mV input and produce maximum power, and maximum power is the the desired result. You do NOT have to have a high voltage RCA, but you DO have to match your amplifier's INPUT requirements with/to the available RCA voltage. Hmmm... could that be a little thing called a GAIN CONTROL? Stick with me here... It gets better. " True, but....its easier to get a clean signal and keep the amplifier more in its efficiency range when dont have to crank the gain up, which would result in less heat and longer amp life.
"and 2: Skipping or not skipping has nothing (as in zero, none, nada, niente, and in no way, shape or form) to do with sampling rate, or RCA voltage. Here's the big serach I did, and here's a Wiki entry, regarding "sampling rate"... "

I said "sampling rate" but I meant oversampling and it does give you a buffer. I also never said it had anything to do with RCA voltage. I may not be an electronic engineer but I'm not stupid.

"
djdowdell wrote:
Speaking of vibrations you MAY have to go to such extremes as concrete for sound damping again depending on your goals, sanctioning body etc.
I'll let that go... pretty much true, EXCEPT for the fact that it's not required for SPL. " Not required, but did u miss the all capital letter MAY in that statement????
"EEEEEENNNNNNHHHHHH! Again, wrong answer. Again, it will all depend on the topography (the design, if you will) of the amplifier. You can get JUST as much output from any given Class A/B amplifier as you can from an equally powered Class D amp. Higher efficency has nothing, again, to do with overall output. The efficiency of an amplifier ONLY determines how much of the input power actually goes out to the drivers, i.e. how much heat will the amplifier make. It's only a number that determines overall waste in the system. " All spl competitors know the more system waste you have the more money you waste, and in spl efficiency is just as important as output if only for the fact it will save you money and increase your db/dollar ratio!!
"
djdowdell wrote:
Subs are really the only major concern and should be matched with the amps (as all speakers should be) and a properly designed enclosure(s) with port tuned to the resonant frequency of the vehicle to maximize SPL. Now granted it will not be "musical" but hey all you want is pressure.
This, I'll agree with... there are several schools of thought, but I'm pretty much of this school. " Thank the lord, lol!!
"
djdowdell wrote:
Now sound quality is another beast all together. I left out level because sound quality is like beauty, its subjective but most have a general consensus on what sounds good. Sound pressure is measured scientifically with no ifs ands or buts about it.
You left out "level" because it's correct to leave it out. Please see my opening rebuttal line. You are also correct to a certain extent in the respect the SQ is subjective, but in the sanctioning of SQ contests, there are very hard and fast rules to judging that, just as there are in SPL competitions. It's a little thing called "Frequency Response". It is desired (if not REQUIRED) to be as flat as possible, "no ifs, ands, or buts". Also quite scientific. There are many other things that are scientifically judged as well, but you are largely correct in the "subjective" part of SQ. " Amen!!! Like I said there may be some things left out, it was late!!
"
djdowdell wrote:
Now sound quality u may or may not have to upgrade alternators depending on your class if you compete. It also doesnt have to a large complicated system. Some of the best systems have the fewest speakers.
Mostly true. I recommend upgrading the alternator in ANY system, no matter HOW small or what it's application. If you add an amplifier, you will add an alternator. " I agree but its not a necessity, hence my may or may not.
"
djdowdell wrote:
Now with sound quality (man, what did i get myself into) is really complicated. U still need high voltage output for a good clean signal but a lot more comes into play like the quality of a/d converters and such. Almost all the specs, THD and frequency reproduction range, etc. come into play.
But it's not scientific, and no hard rules. what differs sql and spl - Page 2 -- posted image. Again, you don't have to have high voltage on the signal leads. ANY pre-amp output section can be made to perform as well as any OTHER pre-amp output section, whether the output voltage is 150mV or 16V balanced. Proper matching and care with installation is FAR more important than a "high RCA voltage". " I say this because it makes things a lot easier when u have a strong clear signal.
"
djdowdell wrote:
Not to mention now u have to use a/b class amps for the midrange/tweeters (unless you can find tubes).
Another wrong answer, Seabee! Some of the FINEST sounding amplifiers in the WORLD are Class D. Spectron comes to mind... Here's the reviews... Bang & Olufsen ICEPower amplifiers are consistently praised as some of the finest sounding amplifiers around, and were at one time called "The Perfect Amplifier". Jeff Rowland embraces PROUDLY ICEPower. All Class D. Alpine (in the PDX amplifier line) and Eclipse (in the XA series amplifiers) both use ICEPower modules. No... It is no longer true that you must use analog amplification for true sound quality. " Touche!! I forgot about those. Told you there may be some omissions.
"I'm really sorry to tear into it like that, but WOW, that was a lot of mis-information." Did you read the last 3 sentences or did you chose to ignore them??? Like I said number one, i couldnt get more in depth because it was late, number two I dont appreciate you trying to say right out I'm false. I just chose not to get into a scientific explanation as not to discourage a future competitor and the statements were made for ease of entry into spl/sql and help him save a little money doing so. Now anyone with deep pockets or sponsors or a great installer can go against the grain or spend a lot of time, money and energy tuning inefficient system but what fun would that be for a new guy? So I was making it statements that were meant to be helpful but by no means the final word on the subject. Thats is why I asked for help not derogatory criticism! It's all good, though no harm done. One love!!

Pure Noize
ice32 
Copper - Posts: 116
Copper spacespace
Joined: June 12, 2007
Location: Australia
Posted: November 18, 2007 at 8:01 PM / IP Logged  
djdowdell wrote:

Ha I love haemphyst! Well let me explain a little about my "false generalizations" if I may. First and foremost I never said that this was concrete. Acoustic theory is much to deep to get into in a forum number one. Number two, I think the question was a general one not a scientific one. As far as acoustic theory goes my generalizations were not completely accurate (i.e. concrete) but for the purposes of the question I just used competitions because Im pretty sure thats what the question was pertaining to that.what differs sql and spl - Page 2 -- posted image.

"NO SUCH OFFICIAL TERM AS SQL." This is something I know already I just used as a reference to the question. And SQL is actually sound quality league in MECA.

WOW, thanks for the huge correction/information there, i do apologize for such a general question, and the wrong terminology.
The question was more getting at when a daily driver is looking to buy a SQ setup, what specs on amps/subs etc should they look for? e.g noise to signal ratio etc
haemphyst 
Platinum - Posts: 5,053
Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: November 18, 2007 at 8:16 PM / IP Logged  
Read the sticky "How to choose and amplifier".
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
ice32 
Copper - Posts: 116
Copper spacespace
Joined: June 12, 2007
Location: Australia
Posted: November 18, 2007 at 8:29 PM / IP Logged  
ok, and are speakers ans subs the same in both SPL and SQ setups?
djdowdell 
Copper - Posts: 60
Copper spacespace
Joined: December 07, 2005
Location: Kentucky, United States
Posted: November 18, 2007 at 9:07 PM / IP Logged  

ice32 wrote:
ok, and are speakers ans subs the same in both SPL and SQ setups?

Yes (for haemphyst, lol) and no. It all depends on the manufacturers design. For all intensive purposes a 12 inch sub is a 12 inch sub they fit in the same box. Some manufacturers design their subs to lean more toward sp or sq, some for both. It also depends on system design as the sum of the parts (not to mention installation and proper tuning) make the whole. What I suggest is get a budget together and get with a local installer or me or someone else in here and discuss what your goals and budget is like and your preferences, type or music, etc. and get you a proper system designed. That way you get the most listening pleasure for your money. Oh, btw, midrange and hi freq drivers are not really geared towards sp but you should to get a more uniform and easier to tune sound i would suggest u try to sensitivity match all drivers as close as possible.

Pure Noize
haemphyst 
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Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: November 18, 2007 at 9:16 PM / IP Logged  
djdowdell wrote:
ice32 wrote:
ok, and are speakers ans subs the same in both SPL and SQ setups?
Yes (for haemphyst, lol) and no. It all depends on the manufacturers design. For all intensive purposes a 12 inch sub is a 12 inch sub they fit in the same box. Some manufacturers design their subs to lean more toward sp or sq, some for both. It also depends on system design as the sum of the parts (not to mention installation and proper tuning) make the whole. What I suggest is get a budget together and get with a local installer or me or someone else in here and discuss what your goals and budget is like and your preferences, type or music, etc. and get you a proper system designed. That way you get the most listening pleasure for your money. Oh, btw, midrange and hi freq drivers are not really geared towards sp but you should to get a more uniform and easier to tune sound i would suggest u try to sensitivity match all drivers as close as possible.
what differs sql and spl - Page 2 -- posted image.
That's all true, but if you buy component sets, the manufacturer will have done all of the mid-to-tweeter level matching and/or padding you need. If you buy individual drivers, then I'd certainly look for matching sensitivity ratings, especially if you're going to design your own passive crossover(s), it'll save you a semi-complicated step in that aspect of system design. With a dedicated amplifier or channel for the sub alone, you'll be able to match sub with mains easily, so don't really work yourself into a lather trying to find a woofer with an identical sensitivity.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
ice32 
Copper - Posts: 116
Copper spacespace
Joined: June 12, 2007
Location: Australia
Posted: November 18, 2007 at 9:30 PM / IP Logged  
Thanks for the info guys
djdowdell 
Copper - Posts: 60
Copper spacespace
Joined: December 07, 2005
Location: Kentucky, United States
Posted: November 19, 2007 at 9:37 AM / IP Logged  
No prob. Thanx for the help Haemphyst!
Pure Noize
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