Going active this time : how to protect the tweeters ?

[Notorious97200 339]

Hello guys,

 

I wish you all a really happy new year !

 

So, I bought a mini dsp for Xmas, and now I want to use it.

I will study the pluggin seriously to find and set the X-over points and the different slopes. I'll take care of T/A too.

 

I will play later with the eq available .

 

I see they're talking about caps to protect the tweeters. How many micro Farads do I need ? How to choose what to buy ?

 

My current amplifier is an Incriminator 3.4. I want to keep it bridged to the Seas mids. 2 x 225 w rms @ 4 Ohms, so my  8 Ohms speakers will have enough power.

 

I need a small amplifier for the tweeters, something on the cheap. Do you have ideas ? What amp would you get ? I may run 6 or 8 Ohms tweeters in the future.

I'm currently using the Focal tweeters I had on my 165 KP set.

 

Thank you for your help.

 

[Notorious97200 339]

Is this one a good idea, or is it too weak for 6 or 8 Ohms tweeters ?

http://www.woofersetc.com/c-3-amplifiers/c-28-two-channel/p-11793-st-2x-zapco-2-channel-170w-rms-class-ab-studio-x-series-full-range-amplifier.html

 

Or this one : http://www.woofersetc.com/c-3-amplifiers/c-28-two-channel/p-11505-xah-1252-cadence-2-channel-500-watts-class-ab-stereo-amplifier-black.html

[///M5 2,833]

Unbridge the amp to start then decide what to buy. Any real amp is fine.

As for how to protect them start with the gain OFF and listen to ONLY the tweeters to find their breakup point. Obviously this is crossover dependent, but for safety and starting points pick 2.5x Fs and a 24db slope. Turn them up slowly and listen for strain.

Unplug and tune the mids. Them blend. Do this at non-reference levels first. Then slowly turn up again while listening to the mids and tweets independently. It is real easy to hear stress on a test when nothing else is playing.

Once here iterations happen optimizing the crossover and eq for each driver again independently. Don't forget to play with every combination of phase as well once you are starting to get comfortable.

And as always ONLy cut with eq, no boost.

[THX_Elite 26]

I have a similar question and am still a bit confused.

 

I ordered the Pioneer DEH-80PRS and will be running it active which means on this HU I will be plugging my tweets directly into my 4ch amps front-left and right channels then my 6.5" door woofers into the rear-left and right channels.  Is there something I will need to do to protect the tweets running in this configuration?

 

This is my first time going active and decided to begin learning with a good HU that will do this.  Down the road when I am more knowledgeable I will move on up to a DSP.

 

P.S.  I have a 1K 4ch Hifonics now but am getting this to replace it very soon:

http://store.soundsolutionsaudio.com/products/ampere-audio-150-4-1000w-4-channel-amplifier.html

[jcarter1885 995]

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Unbridge the amp to start then decide what to buy. Any real amp is fine.

As for how to protect them start with the gain OFF and listen to ONLY the tweeters to find their breakup point. Obviously this is crossover dependent, but for safety and starting points pick 2.5x Fs and a 24db slope. Turn them up slowly and listen for strain.

Unplug and tune the mids. Them blend. Do this at non-reference levels first. Then slowly turn up again while listening to the mids and tweets independently. It is real easy to hear stress on a test when nothing else is playing.

Once here iterations happen optimizing the crossover and eq for each driver again independently. Don't forget to play with every combination of phase as well once you are starting to get comfortable.

And as always ONLy cut with eq, no boost.

If he unbridged the amp then there would be no need to buy any other equipment, since two channels will be open.

[95Honda 486]

Adding anything passive inline with the drivers when using active filters defeats the whole purpose. 

 

This practice has spawned from wives-tales in the late 80's when active was first being used in car audio and people didn't understand it...

[///M5 2,833]

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Unbridge the amp to start then decide what to buy. Any real amp is fine.

As for how to protect them start with the gain OFF and listen to ONLY the tweeters to find their breakup point. Obviously this is crossover dependent, but for safety and starting points pick 2.5x Fs and a 24db slope. Turn them up slowly and listen for strain.

Unplug and tune the mids. Them blend. Do this at non-reference levels first. Then slowly turn up again while listening to the mids and tweets independently. It is real easy to hear stress on a test when nothing else is playing.

Once here iterations happen optimizing the crossover and eq for each driver again independently. Don't forget to play with every combination of phase as well once you are starting to get comfortable.

And as always ONLy cut with eq, no boost.

If he unbridged the amp then there would be no need to buy any other equipment, since two channels will be open.

Exactly. Makes ZERO sense to buy something now as he has a 4 chn amp. MORE than enough power to not only set it up to sound awesome but break shit. Adding another amp would be a waste.

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Adding anything passive inline with the drivers when using active filters defeats the whole purpose. 

 

This practice has spawned from wives-tales in the late 80's when active was first being used in car audio and people didn't understand it...

I was taken aback that it was read somewhere to still try it actually. For the sake of protection it surely could serve a purpose, but of course only if you do everything else wrong and actually running them that way would be absurd.

The biggest thing you can do to protect your tweets is to not turn them on. Seriously play with everything else first. Then shut it ALL off and only listen to the tweets. Then blend them in. Do NONE of it at high levels and CONSTANTLY listen for stress. Shut your sub off completely until you have it really dialed. No need to have anything distracting you from listening to what you are trying to setup.

Even once you have your bearings and know what you are doing it is critical to listen to each and every driver independently during setup.

[Notorious97200 339]

Thanks for your answer.

I read about the caps on the mini dsp website, and some friends of mine still use them (they are oldschool guys !).

 

I'll try to set eveything as M5 said.

I don't want to break anything.

 

I'll try to find the Fs of those tweeters...

 

 

Of course, I'll unbridge the amp first. If I feel I need more power, I'll look at new amp(s). I'd rather keep what I have. Money is tight !

 

Hoping to install and use that dsp soon.

[///M5 2,833]

And stop worrying about 8ohm or 4ohm. In mids that is a ridiculous discussion where the 8ohm drivers regularly sound better and are louder.

If you can't find the Fs of the tweeters you could also measure their current crossover. Just play sine tones through the crossovers and find the -3dB point You could then use that as your baseline although to be safe I'd add a little to it at first. If you are measuring it, I'd also measure the slope. Find the 3dB down point, drop an octave and measure again and see how many dB it is down. You'll then know the slope.

Caps are a waste. Not sure how/why that is on the website. Anything extra that creates an anomaly AND a phase change in your signal path is a mistake.

If you are really frightened what you could do at first is just run the passives you have on the tweeters and not on the mids. This will get you going and then you can remove those and start playing. It would make it a nice a/b comparison for you to hear what a tweeter sounds like without a mid to make sure what you are matching is comparable.

Continue to post up your thoughts/actions. We'll help you through it.

[Notorious97200 339]

I receive a coupon code from my official dealer,  to download the plugin, but I can't have it.

I sent a message to mini dsp. com. I'm hoping for an answer soon.

 

When I register, it's ok. But it seems that I need to buy something else, Paypal doesn't like to send $ 0 to someone ! So, the order can't be filled totally. And I don't have access to the necessary plugin.

 

 

My installer and I were ready to install and play this friday afternoon, but it was not necessary, without the 2x4 plugin.

 

 

The link M5 sent me does not work. It's impossible to share that software like that.  :-( 

[Notorious97200 339]

Ok I have the plugin.

 

I think I'm good with the inputs and outputs, the parametric eq,...

 

Now I need to learn how to set the time alignement. I know it works with delay on the speakers, but I don't know what to mesure in the car. I will look into the minidsp manual, but I would like some tips.

I think it asks me, for both sides, a mesurement for the mid and one for the tweeter.

 

I have one problem : the tweeters are in the dash, firing on the windshield : how do I do ? Where to measure ?

 

Another question regarding the power source : can I split the USB coming from the head unit, to keep one USB input and the second to power the minidsp ? Will I loose something : weak signal, weak power source ?

I will install everything in the car by the end of the week, with my smal IA 3.4 in 4 channel mode.

 

Thanks for your help.

[///M5 2,833]

Not familiar with your car, but a bounce path of the windshield is pretty normal.  Time align the left together alone, then the right, then pair them up.

 

As for the headunit splitting the usb, you can surely try.  I don't think the minidsp requires that much power....but all that being said you should have bought the DC power source from minidsp for $10 as it will prevent turn on thump.  If you mean powering that it is simply done just off an accessory switched source.

[THX_Elite 26]

 

 

Not familiar with your car, but a bounce path of the windshield is pretty normal.  Time align the left together alone, then the right, then pair them up.

 

As for the headunit splitting the usb, you can surely try.  I don't think the minidsp requires that much power....but all that being said you should have bought the DC power source from minidsp for $10 as it will prevent turn on thump.  If you mean powering that it is simply done just off an accessory switched source.

That actually answered a question I had wanted to but not yet asked!  (about mounting my tweets face up to the windshield) thank you! 

[///M5 2,833]

I'd prefer not to, but regularly the other compromises can be worse.  Like an ugly ass dashmat

[Notorious97200 339]

I was afraid to install them on the dash facing up, but it's the stock location, it fits, and I can tell you it's the first time I hear the tweeters so well.

 

But for my T/A process, I think I need to measure the distance between me and the tweeters. So do I need to start from the windshield, or from the tweeters location ?

I still have a lot to learn.

 

I will install that dsp without T/A, first, and play with it after some readings.

[///M5 2,833]

You need to "measure" the full path.  ie, from the tweeter off the reflecting surface and to your ear.

 

I personally prefer to do an acoustic measurement instead of a distance measurement, but am not sure if there is any freeware that would let you do that.  Need software that will measure in the time domain and be able to play some sort of impulse while being time/phase synced.

 

Most sound cards and not phase consistent across the frequency range and while I've never tested I'd bet phones are even worse.

[Notorious97200 339]

I have a laptop. I will be able to play and test with everything.

I don't think I'll try acoustic measurements, as I don't have any mic/software for that, and I'm far from a specialist here !

 

I'll let you know what I feel about the different results.

[THX_Elite 26]

All you need is a usb mic a laptop(and possibly lots of study time).  Here is an example of a freeware program that I will be trying out once my install get's to that point...

 

http://www.roomeqwizard.com/

[///M5 2,833]

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All you need is a usb mic a laptop(and possibly lots of study time).  Here is an example of a freeware program that I will be trying out once my install get's to that point...

 

http://www.roomeqwizard.com/

Good luck with that, lol.

 

I haven't seen a sub-$300 sound card have a matched phase response.  Need both channels synced completely if you truly want to measure delay.  Hell if you could just find a card that had a known delay you could compensate but they typically have a response curve and many aren't even repeatable.

 

USB mics are pathetic and useless as well and surely can't be used.  A real mic taken into a real sound card could have enough resolution for you to measure time response.  I used to sell a lower cost analyzer capable of doing that, but it was still over $8000.  There are definitely much cheaper ways on the market, but I have a large stock of analyzers that make that 8k one look like a kids toy, so I haven't spent anytime looking for a cost effective solution lately.  I am sure there are some, but don't expect it to be that easy.

 

Measuring frequency response is relatively easy however.  I assume that is what REW does.  If it does anything in time I'd like to see how it calibrates the phase before I'd trust any of it.

[THX_Elite 26]

^ thanks for the info about that ///M5, I only recently had found out about REW and have yet to try it out.  I will be needing to setup my 80PRS in active mode as soon as my install is done so I'm trying to gather as much information as I can.  Being that it will be my first time with an active setup I foresee A LOT of trial and error in the near future. 

[///M5 2,833]

The best thing you can do is start to train your ear.

[garychurch84 127]

That's what I did...I sat in the driver seat and started measuring.don't know if that's the way to go or not,still learning myself

[Notorious97200 339]

OK the mini dsp is in.

I've played with it, and first I was disappointed.

Then I changed one knob position on the amplifier, and all of a sudden the tweeters came alive : I had channels turned off with a switch.

 

I'm very happy now. everything is clear, sound nice.

I have a lot of work to do. I have never used a parametric eq in my life.

I have never played with time alignement.

 

So there is a lot of work to do.Gains were set again. I was afraid of loosing output : thanks M5, you gave me confident in this system. It's louder than I would have thought !!!

 

The mini dsp is in the glove box, powered by usb.

I need to try a "usb split" , because I need my usb devices to play my music. I hope I will be able to find one. Or I will need to power the dsp another way.

 

 

[///M5 2,833]

You should power the minidsp off of their 12vdc isolator. Otherwise you are going to have turn on pop.

[///M5 2,833]

And BE CAREFUL. Now isn't the time to test the output, have to tune it first.