[navin]

100Hz and 3kHz are a good place to start. Gunbir used to deal in Hertz maybe he knows more.

[Gill]

Hope,Gunbir adds on something to the discussion,mean while navin ji even we reduce the harshness of tweeter somehow if possible by going active like changing the slops or reversing the phase or by any medium.
One thing more would it be safe to have tweeter playing down to 3khz?

[gunbir]

Originally Posted by Gill

Navin,
I am also inclined for going active but i am not to able to find the info about the Freq range the tweet and mid can handle,On hertz site they have mentioned that full comp set range is 60hz to 23k but i doubt the midbass can go that low,mid bass would be happy around 80hz range
I was looking for Energy Crossover points in defualt crossover it comes with,but couldn't find any info.
Only concern are the drivers strong enough to handle the active system

Originally Posted by Gill

Hope,Gunbir adds on something to the discussion,mean while navin ji even we reduce the harshness of tweeter somehow if possible by going active like changing the slops or reversing the phase or by any medium.
One thing more would it be safe to have tweeter playing down to 3khz?

Hi Gill,

Don't bridge the amp to the components. There is no need for that much power. Especially since it will overpower your sub stage. Ideally, a power ratio of 1:2 (eg. 100w x 2 to fronts, 400w to sub) works for most people, some prefer 1:3. By that standard if you plan to have a 500w (250w x2) front stage, you will need to at least have a 1000w sub stage.

Here's what I suggest:

Option A: Semi Active. Run your HT18 tweets (with crossover) off your HU amp's rear channels and the midbass (with crossover) off the 75.4's front channels. By using fader, you can control the level of power going to the tweeters and blend them to your taste. This option leaves you the other two channels of your 75.4 to bridge and run the sub, as it is now.

Option B: Alternative to the above, you can run the tweets off the 75.4 (with the crossover) front channels, and the midbass (with crossover) off the 75.4's other two channels. Of course, you will need another amp for the sub.

Option C: Active. Akin to option B, except, discard the passive crossovers, set the 9887 to active and set the tweeter HPF at 5KHz, bandpass the midbass between 80Hz and 5KHz.

Again, in Active mode, you can also try running the tweets off the HU amp's front channels. Or off the 75.4, as discussed in above A & B options, only difference is passive crossovers are discarded and active used. The HT18 tweeters don't need a lot of power and I suspect you will find them sufficiently loud off the HU amp. So I suggest trying this first.

Let us know if you need any further help with this.

Cheers!

[Gill]

Thanks for the Input Gunbir,I might be adding an amp for sub,shall be giving the IDQ around 500-600w.
So the JBL will be used to power the fronts only.
I woul like to use 9887 to run whole setup active.I want to see what difference does it make to run system active and what are the pros and cons of each(Passive and active),You solved my confusion about frequency cut offs,
Can tweeter play lower then 5K hz?
another small confusion with option b)How can the system be active with existing crossover of the comps

[gunbir]

Originally Posted by Gill

Thanks for the Input Gunbir,I might be adding an amp for sub,shall be giving the IDQ around 500-600w.

Awesome. The iDQ15v2 will rock your world on 600w.

Originally Posted by Gill

Can tweeter play lower then 5K hz?
another small confusion with option b)How can the system be active with existing crossover of the comps

Yes, you can run the tweet lower than 5KHz. It would be comfortable with anything over 3.5KHz. See the enclosed data for more details on the HT18 tweeter.

As I said, it's sort of semi-active, if you power (bi-amp) the tweets, mids separately and control the level of each driver separately. The passive crossovers still do the crossover function, so its not completely active. Of course if you have the amplification, by all means go active.

Cheers!

[Gill]

Thanks Gunbir for the data and input,surely made things easier for me,what all things need to take care off while running the system active,i mean small things that a novice like me might look over,i know one thing for sure,gains for tweeter has to set very carefully,
gotta go to bed now,will discuss rest later,

Cheers! and thanks again Gunbir

[hydrashok]

Originally Posted by gunbir

Option A: Semi Active. Run your HT18 tweets (with crossover) off your HU amp's rear channels and the midbass (with crossover) off the 75.4's front channels. By using fader, you can control the level of power going to the tweeters and blend them to your taste. This option leaves you the other two channels of your 75.4 to bridge and run the sub, as it is now.

This option sounds the best to me. The added advantage is that you can try this right now, without waiting for a mono amp.

[noidaboy]

shall be giving the IDQ around 500-600w.

Waiting for this to happen

[navin]

Originally Posted by gunbir

Yes, you can run the tweet lower than 5KHz. It would be comfortable with anything over 3.5KHz.

As I said, it's sort of semi-active, if you power (bi-amp) the tweets, mids separately and control the level of each driver separately. The passive crossovers still do the crossover function, so its not completely active. Of course if you have the amplification, by all means go active.

Originally Posted by gunbir

Option A: Semi Active. Run your HT18 tweets (with crossover) off your HU amp's rear channels and the midbass (with crossover) off the 75.4's front channels. By using fader, you can control the level of power going to the tweeters and blend them to your taste.

1. with an fs of 1500Hz 3k/12db is about the minimum XO the tweeter can live with.

2. I like option A as it keeps the tweeter's XO in circuit. seeing the tweeter's impedance curve I would guess that the XO has an impedance flattening circuit implemented in it and by removing this XO you will loose the benefit of this.

[navin]

Gunbir,

this is a 4 ohm tweeter right? if you see the specs it is quoted as 91db/1W, later it is quoted as 91db/2.83V (which for a 4 ohm tweeter is 2W). What gives?

[gunbir]

Originally Posted by navin

I like option A as it keeps the tweeter's XO in circuit. seeing the tweeter's impedance curve I would guess that the XO has an impedance flattening circuit implemented in it and by removing this XO you will loose the benefit of this.

Exactly sir, in the whole trend of active, impedance correction usually gets overlooked.

Originally Posted by navin

this is a 4 ohm tweeter right? if you see the specs it is quoted as 91db/1W, later it is quoted as 91db/2.83V (which for a 4 ohm tweeter is 2W). What gives?

Hmm... Looks like a typo.

[speedzak]

Gill, I 've got to salute you for your interest in DIY and the urge to try out new ways in your ICE. Keep it up!

The option A mentioned by Gunman seems a good point to start experimenting with. You don't have to change your setup much and can be done easily.
My suggestion to try that first and give us some feedback.

[navin]

Originally Posted by gunbir

Exactly sir, in the whole trend of active, impedance correction usually gets overlooked.

not only impedance correction but also baffle step (for home audio) and baffle difraction. Ofcourse the simpler way is to implement these at line level (cheaper too since you need small components).

[low_bass_makker]

Originally Posted by gunbir

Ideally, a power ratio of 1:2 (eg. 100w x 2 to fronts, 400w to sub) works for most people, some prefer 1:3. By that standard if you plan to have a 500w (250w x2) front stage, you will need to at least have a 1000w sub stage.

Hmm I would not take this as a ideal stuff. There can be lots of variations and it will depends on the equipment you are going to install. I have a 500 watts front and 2400 watts sub. ratio is 1:5

I have such a loud sub section because I love SPL. But it is not necessary that I will play it loud 100 % of the time. I tone it down to match it with the front stage.

Also using high rating amps with a speaker with lower RMS rating the main purpose is more headroom. The driver will play stress free without any clipping.

[gunbir]

Originally Posted by low_bass_makker

Hmm I would not take this as a ideal stuff. There can be lots of variations

I don't know where there's a debate. I did not say its absolute, just an ideal that works for most people. I did not say all people.