Help With My Setup!?

arun1963

250 watts rms seems low for a 10" dvc. For 250rms the pa1100.5 would be good. Just set the gain for the sub around 10 o'clock.

vh5150

So for 250rms, won't I need to rewire the sub for 4ohms? The PA's sub channel is 280x1 @ 4ohms. Can I run the sub @ 2ohms? I'd imagine the PA's sub channel @ 2ohms would be +/- 400 watts.

cadenceclipse

if sub is 2 ohms, its 2 ohms, not 4

vh5150

right. its a 4ohm dvc that is already wired for 2ohms. i guess my question is, if i run the sub channel at 2ohms (approx. 400 watts +/-) will i damage the woofer? according to the id website the rms of my sub is 250watts with a program power handling (i guess that means peak???) of 500watts. sorry for sounding like an idiot but this is my first foray into doing my own install and i want to do it right the first time.

cadenceclipse

ull b ok, jus watch gains

arun1963

400 watts for the 250rms sub is fine. Just set the gains lowish and you'll be fine.

vh5150

still at around 10 o'clock or lower?

arun1963

10 would be a good place to start. Try it there. If you find that the sub is bearing down on the mid frequencies (hence loss of clarity in sound) or that the sub bass is kind of boomy and not tight (distortion) you can turn it down a bit.

On the other hand if you find the sub a bit thin, you could turn it up a bit say till 11. 9-11 would be a safe range. Depends on where it sounds best to you.

vh5150

As far as a better sounding / harder hitting sub, should I maybe purchase the IDQ 10 with a 2ohm dvc and run the sub output on the amp at 1ohm? In that configuration, I'd be running 600 watts to the sub. Where should I set the gains if I go with this setup? Thanks all.

arun1963

I would'nt run a sub at 1ohm because of the higher distortion levels. The 400watts you would get at 2ohms would be fine for a 10".

On the choice of sub, it depends on what you want. Do you want the sub to just play the frequencies that your mids miss, with a bit of punch? Or do you want loud db's and to feel the impact of each sub note on your chest (assuming a well tuned setup)?

The sr sub would fill the first need. It has amazing presence but its not the loudest. The kicker solobaric would do for the second need. The ID would be somewhere in between.

I think you want clarity+impact+loudness. The ID 10 wired at 2ohms and getting 4-450 watts would give you what youre looking for

MacLeod

If the amp can handle a 1 ohm load there is nothing wrong with running it that way. There wont be any more distortion and even if there were, you wouldnt hear it coming thru a sub anyway.

cadenceclipse

i guess some1 had 2 let the truth b known.. 600 is too much though..

arun1963

I look at distortion as a sum of all the points that create it. The internal amp in the hu(btw on the p-880 keep this off), IMD at xover points (this is higher in passive mode due to lower xover point between mid and tweets), distortion from the amp, speakers, etc etc. So in this sum game whatever I can reduce or minimise, should make for lesser overall distortion.

So yes while the sub at 1 ohm on its own may not be audible, as part of the sum game it is adding to the total distortion. Thats my logic. If wrong, I stand corrected.

BTW, cadence I don't recall advocating running a 250rms sub at 600watts. But yes 600 watts at 1 ohm may be a bit much for the 250watts rms sub.

MacLeod

If youre using the passive outputs of the head unit then youre not using the internal amp, so there wont be any distortion from that.

cadenceclipse

that was for vh, not u arun. btw whats IMD?

arun1963

True, I was only illustrating it as one of the sources for added distortion.

Keeping my total distortion level low, gives me the flexibility to play with my gains so that I have a bit more headroom.

Youre right that distortion is normally heard in the upper mids to highs. If I want to check for distortion levels, I will turn up the volume to like 54/62 and then open both front doors and listen from like 10 feet away. If it's there, I will catch it in the upper mids/highs.

arun1963

IMD is intermodular distortion. Explanation is in laymans langauge (which is what I understand). Around the xover point a range of frequencies get attenuated. This creates distortion called IMD.

Eg. if your xover point for mids/tweets is say 3khz, at a slope of 12db, it would mean two things. One, that 3khz will be 3db lower and that one octave up would be 12db lower for the mid and one octave down would be 12db lower for the tweet. So, in effect a range of frequencies are getting attenuated and compressed. This compression causes the frequencies to react and create harmonic distortion (ghosts).

Most passive xovers split the signal at under 3khz. Why? I don't know. In active mode if you set the xover higher say 5khz, the squished range would be 2.5 to 7.5khz. There is less 'sound' in this range than say the 1.5khz-4.5khz, (xover point at 3khz), hence less IMD.

You would get this at both xover points. Except that at the lower end, you would'nt hear sub bass distortion at nominal levels. At medium levels, while you may not hear it directly, you may hear its impact on the lower mids. Jury is out on this one.

ok ntd re the wattage. What about the other comment......lol...........its ok.

MacLeod

I think youre overthinking things a bit. Ive head of phase issues with crossover frequencies, which is why a lot of people say to not use odd number order slopes like 6, 18 or 30. I personally have never found this to be true. Never heard of IMD tho.

arun1963

I'm sure you're right on the overthinking bit. Is there a cure for this madness/sickness? Apart from not listening...lol.

You can google for intermodular distortion. It's on wikipedia as well. Have to admit tho I have'nt done a placebo/real test for this. But I think the crux is accurate.

The thing is that there is so much stuff out there, that sometimes it becomes difficult to seperate the grain from the chaff. Which is where guys like you come in.

You got to take more classes here bro....;)

MacLeod

Yeah dude, you need to quit reading so much stuff. This is audio. Go out and tune your car by ear. Formulas, equations and fancy scientific terms will drive you crazy.

arun1963

Funny thing is that although I read up a bit on the net, the 4-5hrs of listening and tuning per day is all by ear. All the formulae and theory just slip out the mind.

MacLeod

Yup, the only thing even remotely scientific I do when Im tuning is to use test tones and an SPL meter to level match left and right. Then even that if fine tuned by ear once Im done.

cadenceclipse

u don't set gains with a multimeter? think i gotta try that..

MacLeod

**** no. Never even tried it. Have always done it the old fashioned way. 30/35 volume and turn the gains til I hear clipping/distortion then back it down a smidge. Thats usually the 9-10:00 position. And after 20 years of playing with car audio, I have yet to blow a speaker. Even in SQ judging where the judges routinely crank up certain tracks to 32/35 volume.

cadenceclipse

me 2, interesting..except 4 me its the 8:00 position(or all the way down). any idea what my prob can be? amps down, volume up(79/80). i get distortion after 78 now(stil crank to 79 on highwayy) and also sense it at around 76 and up. also 79 sounds like volume where components(system) should at least be playing at(sounds about right level for 75w into my components and 150 into sub). maybe i just need to bi-amp, specially since components and sub have low sensitivity and i'm only using front speakers now..?
do u tell them 30, but they go higher anyway?

vh5150

OK, so I'm cleaning out the closet yesterday and come across a brand new Rockford OEQ2 system EQ. Should I use it in the signal chain or just stick with the EQ'ing off of the HU?

arun1963

MacLeod wrote: »

Yup, the only thing even remotely scientific I do when Im tuning is to use test tones and an SPL meter to level match left and right. Then even that if fine tuned by ear once Im done.[/QUOTE]

I'm really glad you mentioned that.

The eq settings that balance and level match the test tones, when used on normal music, gives inert and dead sound. Its located correctly, but everything is squished together. It lacks in width, depth and that vibrant 'alive' feel. Getting the sound alive is the last bit of tweaking.

The toughest thing for me though is to know when to stop. While tuning, I have often hit the ideal setting only to have everything fall apart 10mts later because I tried to over think/tweak while chasing a very small delta. So for me, knowing when to stop is the really difficult bit....lol.

arun1963

I would say go with the processor on the p-880. The oeq2 is more of an equaliser than a true processor. Even here, it only gives you control over 10 frequencies. Your HU gives you 16, apart from time alignment and ability to set an active 3way network.

arun1963

Cadence: Re your distortion issue, what are your xover points and slopes. Dont think its a gains issue becoz you've set both pretty low.

arun1963

appologies to vh for multiple conversations in his thread