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Originally Posted by DerAlte "Crossovers"? Or "Filters"? There is a difference, you know. |
Sure Crossovers are used to filter the musical spectrum!
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Originally Posted by DerAlte Oh no, please don't restrain yourself - we love to hear a technical dissertation! |
Your way of asking questions is better since that would give in depth details step by step instead of a long post with confusing details.
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Originally Posted by DerAlte AND you have NOT set HPF at the A channels of the amp? I fail to see the problem if HPF is set, EVEN if there is a fixed HPF at 80 Hz with a -12dB rollover, no matter how much boost is given at the HU Equalizer. |
Over here I will base the matter only on speaker cone excursion or protecting the driver from bottoming out.
The 12db roll off sometimes doesnt help.
Many a times you need 16db or 24db slope (I agree those slopes exist not just to protect the speakers but lets use the idea for the particular reason).
If you car has 4 inch driver. 80hz wont really help if the owner has a habit of cranking it up.
The simplest method is to reduce the gain if you hear speaker popping (bottoming out). I used to do that on the kenwood amps long ago. I believe most of the people are tuning in this way.
Setting 80hz hpf on 12db slope doesn't mean the speaker wouldnt see 50hz. It only means 50hz would be heavily attenuated compared to the -3db attenuation of 80hz.
I am not against the kenwood amp, they are the best and reliable amp within the price range. Never had a failed one (unless you dipped it in salt water). I am only saying If i were to choose an amp, I would prefer one with variable crossover settings on HPF and LPF.
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Originally Posted by DerAlte I am a bit confused here:
1. Are you describing your *previously* mentioned scenario, or is this a new scenario? I was expecting an answer w.r.t. your previous scenario |
Yes, I can explain.
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Originally Posted by DerAlte 2. How is Phase Cancellation getting corrected by pushing up the LPF to 80 / 100 / whatever frequency? |
Phase cancellation might not be completely solved by this method.
First of we need to know why its there or whether its phase cancellation or something else. (Bad install, Reverse polarity on speakers or sub etc...)
(I bet there will be question on reverse polarity and phase, are those the same?)
Anyways I will outline the step quickly without details.
Are the speakers all on the same phase and polarity?
Easy way to know that is to check the polarity.
Then use a phase testing tool to confirm.
Use the balance control on Head unit for the following two steps
* Play front speakers on test tones from 40hz onwards to around 125hz to see if they are not cancelling out.
* Play rear speakers and try the same method above
Use the Fader control on Head unit
* Bring in slightly the front speakers and if there is no cancellation, its time to bring in the sub stage.
Use Sub control on Head unit or remote
* Bring in the sub on each of test tone range from 30 all the way to 125hz. Listen carefully and it will be evident where the speakers are cancelling the sub or vice versa.
For the context here, lets say we found a phase issue and it can be fixed only by messing around with Crossover settings.
May we want to try settings at speakers on 100hz -12db slope and sub on 80hz -12db on the amp to rectify this. So how would you do this or atleast try to see if that can fix if your amp has fixed setting.
(Now lets say I run a business and I was doing this installation for a customer. How do i explain to the customer during a tuning session that I am limited on tuning due to this? Would sound really lame.)
An RTA helps at this moment to see if there is a dip in the spectrum or listening can help if you know what to look for.
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Originally Posted by DerAlte * Isn't the sub anyhow not supposed to handle that F region (normally installed, not F response)? |
Depends on the install, vehicle and enclosure. Generally setting the LPF at 80hz works and a big population of music lover don't understand the issue at all. They know the music but they dont understand musical spectrum.
Generally people add a sub and become happy about those 40hz and 50hz boost. Eventually they complaint that the punch is lacking or the sub has too much rumble.
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Originally Posted by DerAlte
* If one is using less-capable speakers in the front (cannot go lower than 120Hz, for example, which may need the sub to play higher), why in the first place is the sub put in? Why not NOT SET the LPF at all, since the sub will naturally not make any recognizable sound above 250Hz? |
I can do that if i have a kenwood 350 amp and basic kenwood amp. You would hear a lot of the music coming from the sub.
It might sound really bad if we try this on a sub that doesn't have the required frequency response. (30Hz to 100Hz only subs)
And there are subs with frequency response all way to 1000hz and it can be smartly installed to get loud if sound stage is not a problem.
But Lets say you do not set crossover on a sub that does 1000W RMS and the amp is truly capable of driving that power. You will soon cook the Voice coil.
Cooling is a huge part in subwoofer construction. Those 120hz upwards of musical power will not help much in cooling the voice coil as there wouldn't be much excursion.
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Originally Posted by DerAlte
* If there is 'phase cancellation' (not able to visualize why only in the 80-100 Hz region) - why is the Phase cancellation not being analyzed and tackled? As I mentioned above, it can only be lack of capability in that region in the front speaker, and not 'phase cancellation' (which has a different genus) |
So in short, If there is a phase problem after you have done proper installation, phase checks performed, amp gains and standard crossover settings dialed.
It could be due to the lack of capability of the speakers or sub. And it has to be analyzed before just running to the crossover and changing it. For me crossover setting is the fine tuning before i touch the equalizer for tonality.
The only reason why we are stuck at 80hz is because of the topic on the 80hz fixed hpf of kenwood amp.
Once again all the above is applicable on case to case basis and doesnt mean Kenwood amp is bad.
And generally the idea is to feel that the bass upfront and blending with the front speaker stage.
What does this mean to me and why am i going on an on. When I set the crossover correctly I feel the bass upfront. (TA is another subject that i dont want to touch)
Hope all the above information helps someone!
We are all learning as SQ and SPL is extremely challenging in car audio.
(Same goes for mono amps with phase control knob - I would prefer amps with phase variation control)