Will I run into any problems doing this on a 4 channel amp.

Front speakers on 1&2 channels

rear speakers in parallel off 3rd channel

center speaker run off 4th channel.

thanks!

Is each individual channel have it's very own gain settings? IE; there are 4 gain knobs rather than 2?

If there are only 2 knobs, I'd imagine you might run into impedance conflicts. But, I've never tried this before.

Just a thought.

~Levi

It will all come down to the load being placed on the amp. It is impossible to say without having full details.

That would do some really funky stuff to the amp bro. The rears would have to be something like 2 ohm drivers wired in series to give you a 4 ohm load, and the center then would also have to be 4 ohm, you'd have to mono the signal into channel 3/4.

Make your life easy and get one of the mini monoblock Xtant amps designed to run full range.

Front and rear speakers are 4ohm, I can get either 4 or 2ohm for the center.

There are only 2 gain knobs on the amp.

the amp specs are:

• 150W x 4
• Per channel into 2 ohms : 150W x 4 (<=1%THD+N)
• Per channel into 4 ohms : 150W x 4 (<=1%THD+N)
• Brigded 4 ohms: 300W x 2 (<=1% THD+N)
Dimensions
• Crossover Frequency : 1/2Ch + 3/4Ch, 30Hz-400Hz HP/LP/Off (-12dB/oct)
General
• Frequency Response: 20Hz - 20kHz (+0,-1dB)
• Signal to Noise (S/N): 100dBA (Reference to Rated Power)
• Input Sensitivity (For Rated Power): 0.2V to 4.0V (1.0 at Center Detent)
• Input Impedance: 10k Ohm


I'll look into mini monoblocks if it's not possible then.

Thanks!

run the 4-channel for the fronts/rear and get that mini amp for the center...going to be the easiest, most cost effective way to have a 5.0 sound setup.

They way you have it setup, MAY work. But it may not.

Things you need to consider:

Do you have a 5.1 source, or are you using something to generate the signal?
How are you going to mix the rear channels?
What are you really trying to get out of this?


You can finagle the lack of proper independent gain control by using some of these:

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=266-234

They have them in 1dB, 3dB, 6dB, and 12dB.

But really, it isn't worth it.

If i were you and REALLY wanted to do this, i would run the rears from the HU and run the center in mono using 3-4 by Y'ing the front inputs (RCA) and then adding an L-pad to the center to attenuate it at will.

Over all gain control, and the ability to attenuate..

okay, yeah.. I'll get a mini amp.. or to save space swap out my sub mono for this 4 channel amp I have laying around and bridge the sub..

Any idea what brand your amp is? Model? Can it be run "mixed-mono" .

Presuming it can,...the way to wire it is to run the fronts off channels 1+2,....3+4 for the rears,...and wire the center channel to channels 1+2 or 3+4 as if they were bridged. You will essentially be running 2 of the channels bridged and stereo at the same time. This used to be common in "old'school" systems.

I have in the past run 13 speaker setups with 2x12" woofers bridged,...a center channel bridged,..and 10 stereo speakers (3 way in front, 2 way in rear) off the same 2 channel amp.

This will of course mean that the amp is "seeing" a 2 ohm load for the center channel,...but you can simply add a 4 ohm resistor or an "L" Pad to dampen the volume of the center channel down.

Start with the 4 ohm resistor in the pos wire to the center channel speaker,...and if it is still too loud,...go with a bigger resistor,...if too quiet,...a smaller one. An "L" Pad from Radio Shack gives you a passive volume knob to make the adjustment with,..and maintains the impedance.

If you wire the center to the rear channels of the amp,...you can use the fader to adjust the center to the fronts.

^
it's an alpine pdx 4.150

I'm not sure if it can be mixed/mono.

Is there a risk of damage to the amp if I do the above?

That's Daishi00 territory :)

~Levi

Presuming it can,...the way to wire it is to run the fronts off channels 1+2,....3+4 for the rears,...and wire the center channel to channels 1+2 or 3+4 as if they were bridged. You will essentially be running 2 of the channels bridged and stereo at the same time. This used to be common in "old'school" systems.

I have in the past run 13 speaker setups with 2x12" woofers bridged,...a center channel bridged,..and 10 stereo speakers (3 way in front, 2 way in rear) off the same 2 channel amp.

This will of course mean that the amp is "seeing" a 2 ohm load for the center channel,...but you can simply add a 4 ohm resistor or an "L" Pad to dampen the volume of the center channel down.

Start with the 4 ohm resistor in the pos wire to the center channel speaker,...and if it is still too loud,...go with a bigger resistor,...if too quiet,...a smaller one. An "L" Pad from Radio Shack gives you a passive volume knob to make the adjustment with,..and maintains the

So, basicly, your saying what i just said.... lol... with a little added detail of course... lol

If i were you and REALLY wanted to do this, i would run the rears from the HU and run the center in mono using 3-4 by Y'ing the front inputs (RCA) and then adding an L-pad to the center to attenuate it at will.

Over all gain control, and the ability to attenuate..

I just took a quick at the PDX amps, i couldn't find anything on mixed mono, but i doubt it would be a problem as they are the high line models...

So, basicly, your saying what i just said.... lol... with a little added detail of course... lol


Not quite. You don't need to "Y" the RCA's to get mono. If you wire a speaker to a pair of channels "Bridged",....you will get mono. It's a better way to get mono than "Y" ing a set of RCA's. I've never been sure how wyeing RCA's effects the pre-amp stage of different head units.

If you can run mixed/mono (tri-mode) you won't need to run the rears off the deck. you can run bridged mono for the center channel and stereo pair off th same 2 channels simultainiously.

You can also run the fronts and rears off the same 2 channels. I do this all the time. I just wire in 10 ohm resistors in the positive wire of the rears. This quiets them down. The amp sees just under a 4 ohm load (3.6?) and all is well. I never run more that 20-30 watts to the rears anyway,...and if I'm building an SQ system,....I leave the rears disconnected altogether.

If you do that,...he would still have 2 channels left to run a woofer or center.

I know what your saying about the Y cables, i actually had a complete post written up and "re-thunk-it" and missed changing those parts...

We are on the same page, is all I'm sayin...

okay,

I'll try tri-mode/mixed mono. I'll contact alpine support just to make sure.(edit:I just called and the tech guy confirmed that it was okay)
Oh yeah, what's the correct way to place a resistor, do I just stick it in the + terminal along with the wire, or does it have to be soldered between the speaker wire and amp?

Thanks

duckstu..and others,

what if the bridged speaker I run is 8ohms, will that be okay? I'm considering this tang band

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-821

I am guessing yes.. that higher loads are more okay for an amp than lower loads.

You'd be fine running an 8 ohm driver.

You'll actually get the same output out of that Tang Band as a standard 4 ohm car audio driver (of the same sensitivity) due to the differences in how both are measured, so it should tie in nicely to the other two front drivers. the only MAJOR issue I see is the fact that it only can handle 25w RMS, and even in a load above 4 ohm on the amp side of things you're going to be feeding it well well well over that power rating. I wouldn't be surprised if you end up frying it after a few weeks. Another issue is that the Tang Band will most likely sound completely different than the other front drivers and annoy the piss out of you. That is why most people who are trying to run a surround sound setup try to use all the same drivers in all locations.

You're not really going for a "true" surround sound though right? Just want to trying to center the vocals more correct?

What HU are you running?

You're not really going for a "true" surround sound though right? Just want to trying to center the vocals more correct?

What HU are you running?

yeah,

I'm just trying to center the vocals, although I wouldn't mind having surround sound as an option. The problem with matching my front components is that it would be crazy expensive to buy another set, polk SR6500 (http://www.polkaudio.com/caraudio/products/sr6500/).

other options that were recommended to me are:
polk db401 (http://www.polkaudio.com/caraudio/products/db401/)

Vifa XT tweet and Scanspeak 4", Cant' find price on scanspeak. I don't know how to make a crossover.

Alpine SPX-107R (http://www.ikesound.com/product-product_id/3025), Expensive.

Legatia L4 (http://www.hybrid-audio.com/legatia_individual_drivers.htm), won't be in stock for few weeks, mid to high $100 range.

Currently I don't have a head unit. I'm running an ipod through a
RF 3sixty.2. I'm planning to install a carputer later, so my sound will be going through a usb or firewire sound card. I may or may not keep the 3sixty.2

thanks!

if you have a 3 Sixty.2 why don't you just run an active front stage and take advantage of time alignment to center your vocals? It's going to take about the same amount of work to do a center channel cleanly as it would to wire up your setup for 2-way active front.

if you have a 3 Sixty.2 why don't you just run an active front stage and take advantage of time alignment to center your vocals? It's going to take about the same amount of work to do a center channel cleanly as it would to wire up your setup for 2-way active front.

Agreed, adding another driver is going to make it more difficult to tune properly. With the 360.2 you should have no problem getting a good center image from just the front speakers. Spend your time on tuning what you have instead of trying to add another speaker, it's cheaper too. :)

Where are all of your speakers currently mounted? Something as simple as moving your tweeters might make a huge difference as well. Did you try different locations before permanently mounting them?

Where are all of your speakers currently mounted? Something as simple as moving your tweeters might make a huge difference as well. Did you try different locations before permanently mounting them?

Also a very important point. If you have them in some place such as the stock location then you're asking for trouble. The SR6500's have an insane response curve on and off axis so they are very forgiving to how you mount them in terms of sail panels, a-pillars etc... couple that with the processing power of the 3Sixty.2 you are golden.

BTW if you decide to sell that 3Sixty.2 in the future let me know :D

yeah, I've tried the time alignment using the 3sixty and to be honest.. it sounds amazing, lol. But if you remember from a previous thread, I wanted to center the image for both passenger and driver and time alignment pretty much screws over the passenger. I currently have the tweeters in the sail panel and the gauge hump on the driver side messes things up. This week I'm going to try to move the tweeters up to the a-pillars, so maybe that will be good enough.

.. If I do decide to get rid of the 3sixty, I'll give you a good deal on it for sure.

ah, that's right forgot about that.

I still maintain my belief of SCREW THE PASSENGER. :D

the a-pillars will help with that a bit, but you have to remember that the piller slopes backwards, so break out some MDF to get it aimed correctly. If you need any help on that let me know as I had to go through the same thing myself.

Sweet on the deal :D

One last question, i think. I'm looking into l-pads. The highest rated I see on parts-express is 100 watts.
The pdx is 150X4rms, 300x2rms. Can a 100Watt l-pad handle this. Also, is an l-pad with an 8ohm impedence okay?

Thanks.

I have no idea what an l-pad is haha.

As for handling it...sure for two reasons. One, you set the gain on the amp, so you can easily set it for less than 150w on those particular channels. Two it's an 8 ohm component so it's going to use roughly half the available power.

I have no idea what an l-pad is haha.

As for handling it...sure for two reasons. One, you set the gain on the amp, so you can easily set it for less than 150w on those particular channels. Two it's an 8 ohm driver so it's going to use roughly half the available power, but should maintain around the same output as a 4 ohm car audio driver.

okay cool, thanks!

L-pad..... http://en.wikipedia.org/wiki/L_pad

Ah, thanks, I better edit my post a bit now. You 'da man.

I would avoid using a rheostat, as it just wastes energy. I would attenuate the volume on the signal side of the amplifier.

I got it working and it sounds great!

http://img.photobucket.com/albums/v203/ironfinger/midclosedlow.jpg

I used the L-pad as suggested, works awesome.

The Tang Band sounds kind of harsh up high so I had to band pass the sucker. However, I did succeed in raising and centering the soundstage. I sat there toggling the center channel on and off..wow what a difference. Now I can't imagine my sound system without it.

Thanks for the help you all!

http://img.photobucket.com/albums/v203/ironfinger/midnogrilllow.jpg

http://img.photobucket.com/albums/v203/ironfinger/midopenlwo.jpg

Looks pretty good! Is the back of the speaker sealed off? I can't really tell from the pics.

He probably doesn't need to seal it off. The bass "wrap-around", where bass is cancelled if the front of a driver isn't seperated from the back,...only gets noticable below 300 hz roughly. Most center-channels you try to run between 400 hz and 5,000 hz,...the area of the majority of vocals.

You also don't get much of the ratteling issues as you cross it up that high,...which helps out a lot as you are likely installing it with no cabinet and in a thin piece of plastic.

I would avoid using a rheostat, as it just wastes energy. I would attenuate the volume on the signal side of the amplifier.

Of course, the power he is "wasting" with an L-Pad is power he doesn't want going to his center speaker,...which is why he installed an L-Pad and then turned it down.

I think the fuel costs of wasting a few watts from 2 channels of his front amp into an L-Pad would amount to a few nickels a year in extra gas cost.

He could also do it with resistors. A 4 or 8 ohm resistor might do the trick nicely and would also allow the amp to run at a lower impedance,...which could reduce distortion just slightly (at least the amount added by the amp).

In the past,..I have used an L-Pad for a few days to get the center channel volume right where I want it,...and then used pink noise cd track and a db meter to see what the volume wis. Then removed the L-Pad and tried different valued resistors until I got the volume (as measured by the db meter) back to where is was with the L-Pad.

The L-Pad in that case had simply allowed me to easilly tweak the volume here and there over a few days of driving until I decided exactly where I wanted it.

I can't say there's a difference between the 2 methods in SQ,...but it was a cleaner install when done,...and better in theory at least.

He's using an 8 ohm driver,...so to the amp,..he will have 4 ohms,..just like his lefts and rights probably are.

Yeah, I didn't enclose the back. I band passed at 80-8000hz. I am noticing the cancellation below 400hz, however I kept the spread wide because all the adjustments also affect the rears, which I want a wider range.

Yup, the L-pad does leave for a messy install, wires everywhere and nowhere to mount it. But I think I can live with it since everything is hidden under the rear storage floor.

I got a chance to tweak it some more and it sounds really good with the center time delayed about a foot from the sides. It also turns out that the volume level doesn't need to be cranked up much to have the desired affect.

As for the sound stage. It definitely narrows side to side panning affects, but that's the only downside. The benifits are tremendous. It gives tremendous height, breadth, center, and unity. Can't ask for much more really :alien:

Of course, the power he is "wasting" with an L-Pad is power he doesn't want going to his center speaker,...which is why he installed an L-Pad and then turned it down.:rolleyes:

oh man, I experienced the smell of some melting plastic this morning :(
I must of had the L-pad cranked to high.. well I'm hoping it's this cheap tang band and not something else that's frying..

Rutt Rohh Raggy....

Hey,

So I want to replace the center speaker with a speaker rated at 4ohms.

If I hook up the 4ohm speaker to the 8ohm L-pad, what will the final load at the amplifier be?

Thanks!

btw..is it okay to wire a 4 ohm speaker to an 8ohm L-pad?

nevermind.. I was at autozone and spotted this cheap and tiny 18rmsX2ch amplifier. So, I bought the sucker :D.

looks great!