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Car Forum / Driving, Maintenance, Tuning / Car Audio / May 2004System I'm designing - two questions
I'm designing a system for my 93 Mustang hatchback. I've built a bunch of PC's, but this is my first car audio system, and I'm trying to take the "measure twice, cut once" approach. I don't want to announce my arrival from a half mile away, but I am aiming for SQ and lots of the proverbial "clean, tight bass" at low to moderate volume. Based on what I've read on this group and elsewhere, I have decided on Polk DB series speakers - DB6500 components in front (mids in doors, tweets in dash), and DB570 coaxials in back. I'll get a JL 300/4 amp to drive the speakers. To get this "clean, tight bass" without giving up too much hatch space, I'm going with a JL 8W7 sub in a sealed enclosure. I'll drive the sub with a JL 250/1. I'd like to keep my (older) Alpine cd head unit, which has no preouts. I'll run speaker-level to the amps. So I have two questions. Will I get good results running speaker-level to the amps? Or will it make a real difference if I go ahead and upgrade to a head unit that has preouts? And, will this little 8W7 sub give me this bass I want? The alternative (I guess) would be a 10W7 and a 500/1 amp. TIA, John I'd strongly recommend listening to any speaker before taking some else's word for it - after all - we don't all have the same listening tastes or the same budget available to spend. For the low-end, generally for an 8" woofer to work appreciably, you'll need to do some sound deadening to the vehicle as road noise/engine noise will drown out a good chunk of the sound a woofer that size will produce, (at least in my experience with 90's mustangs). To underline that all, without knowing you - it's impossible to say "yes, the 8" will give you the bass you want". Again, you'll need to check with your local dealer and see if they have one on demo you can hear yourself. As far as keeping your existing headunit, I don't think the 300/4 or 250/1 accept speaker-level inputs so you may need to consider replacing the head unit or hunt around for an amp that 'still' has that feature. n8 > I'm designing a system for my 93 Mustang hatchback. I've built a > bunch of PC's, but this is my first car audio system, and I'm trying [quoted text clipped - 23 lines] > TIA, > John n8, Thanks for the advice. I have heard these subs in a demo room but I know it's going to be VERY different in the car. I have not heard the Polk DB speakers though (no one had them on demo), but you're right - I should not buy anything without hearing them first. JL has some sample configurations on their web site, and one of them shows a factory head unit with speaker level going to their amps. So even if it will technically "work", I wonder if the SQ will be as good as actual preout (line level). John > I'd strongly recommend listening to any speaker before taking some else's > word for it - after all - we don't all have the same listening tastes or the [quoted text clipped - 41 lines] > > TIA, > > John I have a friend wo swears by polk DB subs. They hit really hard in his Altima. I personally will only buy fosgate. I love my HX2 subs > n8, > Thanks for the advice. I have heard these subs in a demo room but I [quoted text clipped - 60 lines] >> > TIA, >> > John That's great - but again, you have to recognize that not everyone has the same tastes... n8 > I have a friend wo swears by polk DB subs. They hit really hard in his > Altima. I personally will only buy fosgate. I love my HX2 subs Very true, I think noobs often forget that and think it's all about "poundin". And personally any time someone says I only buy brand "X" I usually dismiss them as a noob with no real understanding. I may be wrong 1 out of 100 times but oh well. Les > That's great - but again, you have to recognize that not everyone has the > same tastes... [quoted text clipped - 3 lines] > > I have a friend wo swears by polk DB subs. They hit really hard in his > > Altima. I personally will only buy fosgate. I love my HX2 subs > That's great - but again, you have to recognize that not everyone has the > same tastes... That's true. But I've owned Polk dB subs and they've sounded no different from any other sub I've had in my car. > That's true. But I've owned Polk dB subs and they've sounded no different > from any other sub I've had in my car. One difference: they went <poof!> much easier. I must have been clipping. <g> a head unit without pre-outs? christ, that must be ancient.. first off, if you want clean, tight bass, go with an amplifier with a damping factor of 500 or better. Signal to noise ratio doesnt matter so much with bass frequencies, 95 dB or higher is fine.... if it doesnt advertise what the damping factor is, then chances are its shitty.. i personally never really liek any of the JL amps for SQ, always thought they sounded too harsh, even when i had the Clarion DRX-9255 for a head unit. you want good SQ for a cheap price? im sure theres plenty of people that will argue with me on this, everybody has their opinions.. but The "low profile" Farenheit series from Power Acoustik, which is now discontinued, produced better SQ scores than my xtant, soundstream, or( i know im gonna get sh.t for this!) my ESX quantum amplifier setup. actually.. the ESX quantum amps( Q 175-2 and Q120-4 )had a slightly softer tonal quality, BUT, it distorted more at higher volumes.. so its a toss up.. the PA farenheit series is discontinued now, but if you want one, i can probbaly find a supplier that still carries it, email me at aaronrus@tampabay.rr.com > I'm designing a system for my 93 Mustang hatchback. I've built a > bunch of PC's, but this is my first car audio system, and I'm trying [quoted text clipped - 23 lines] > TIA, > John > a head unit without pre-outs? christ, that must be ancient.. > > first off, if you want clean, tight bass, go with an amplifier with a > damping factor of 500 or better. Go with any modern amplifier. The damping factor is a moot point nowadays and is merely a gimmick marketing tool to show a big number. Signal to noise ratio doesnt matter so much > with bass frequencies, 95 dB or higher is fine.... if it doesnt advertise > what the damping factor is, then chances are its shitty Or they realize that every modern amp already has a high enough rating and there is no need to state it. .. i personally never > really liek any of the JL amps for SQ, always thought they sounded too > harsh, even when i had the Clarion DRX-9255 for a head unit. you want good [quoted text clipped - 5 lines] > Q120-4 )had a slightly softer tonal quality, BUT, it distorted more at > higher volumes.. Where to start?? Aaron, let me ask you a question and perhaps it will help dispell the myth. How can the amps sound different? When you measure then, scope them, whatever and all the results come out with differences below the threshold of hearing then how can they possibly sound different? When you operate an amp within it's linear limits, ie no clipping, then you will not be able to hear a difference, especially in a car. Your ESX distorted more at higher volumes because you were either clipping it or it was defective. A softer sound is often associated with a lower volume. The physics of the matter support the fact that they sound the same, the I heard it argument is so full of holes it doesn't hold water. But I won't give you any crap about the cheaper amps, if they deliver the power and reliability someones after then by all means go for them. I have used Profile and Lanzar in many cars and have always been pleased. I don't care for JL amps personally, not because they are not good but I think they are overpriced for what you get. Les >> a head unit without pre-outs? christ, that must be ancient.. >> [quoted text clipped - 10 lines] >Or they realize that every modern amp already has a high enough rating and >there is no need to state it. Absolutely right. As long as the damping factor is at least 50 or so, you're not going to hear a difference, and ANY modern car amp exceeds that number by a large margin. The main reason modern amps have such huge damping factors is because high damping factors are a by-product of the large amounts of negative feedback used in solid-state amps. Damping factor doesn't say anything about the quality of the amp or how it will sound. It says more about the particular circuit topology the designer chose to use (no feedback versus low feedback versus high feedback). If you look at older tube amps used in home stereos that have little or no global negative feedback, some of them have damping factors as low as 20, and they sound just fine. You have to get down around 10 before you're almost certain to hear a difference, and even then, it might not sound worse, just different. So like Les said, any modern amp is going to have such a high damping factor that there's no reason to mention it, except as a marketing tool. The same is true of signal-to-noise ratio. My old Linear Power amps only had an advertised SNR of 80 dB, but no one ever complained about them sounding noisy, and they sold a butt-ton of them. To put it in perspective, a SNR of 80 dB means that the signal is approximately 100,000,000 times stronger than the noise. So, if your amp put out 100 million watts of clean signal, there'd be one watt of noise mixed in with it. Trust me, you're not going to be able to hear it. You can see the folly in selecting one component over another just because one has a SNR of 90 dB and the other has a SNR of 100 dB. Scott Gardner > Absolutely right. As long as the damping factor is at least 50 or so, > you're not going to hear a difference, I'd argue 10. And that's assuming everything else, including the listening room and the hearing/training of the listener are perfect. >> Absolutely right. As long as the damping factor is at least 50 or so, >> you're not going to hear a difference, > >I'd argue 10. And that's assuming everything else, including the listening >room and the hearing/training of the listener are perfect. I'd agree with you, but the only scientific experiments I found indicated that there could be audible differences with a damping factor as high as 20 (as you said, assuming an ideal environment and a well-trained listener). To be conservative, I said 50 in my post. With modern solid-state amps, it hardly matters, since they're all be well over 50 anyway. Scott Gardner > >I'd argue 10. And that's assuming everything else, including the listening > >room and the hearing/training of the listener are perfect. [quoted text clipped - 5 lines] > With modern solid-state amps, it hardly matters, since they're all be > well over 50 anyway. Dick Pierce suggests 10 in his damping article. I think an argument can be made that in practical applications you can go even lower than that. Which brings us back to the underlying point - damping factor doesn't matter. |
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