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Hooking speakers up Parallel


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#1 dembits

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Posted 05 December 2005 - 07:22 PM

Okay, I am relatively new to hooking up sound. I have read some of the old posts and think that I have a decent idea of what is going on, but want to make sure before I buy the wrong amp  or hurt my speakers. The guys at my local amp store are so into getting money out of me that they can't or won't take the time to really help me. I recently purchased a pair of MTX TP 112 speakers that according to the manual can handle 150 Watts of continuous power at 8 ohms. I also just got some Gemini GT 1002 speakers. Their website says that they can take 90 watts at 8 ohms, but the back of the speaker says 160 watts. I am going with 90. I would like to hook all four speakers up to one amp , creating a 4 ohm hook up and have read about hooking them up parallell. Based upon the .8 to 1.25 ratio, I think that the XLS 402 would work out, giving them 400 watts on each side at 4 ohms. However, I have a few questions:

1.  Am I correct in my selection?

2.  Can these be hooked up parallel?

3. When I do hook them up parallel, can I just use the banana plug to connect to the amp with one speaker cable and then just plug another banana plug into the back of the previous plug? As long as I don't hook them up upside down, it seems like this would work. (Hopefully this makes sense)

4. For the highest quality sound, can I hook up one MTX and one Gemini to each channel or will I have to hook up both MTX's to one side and both Gemini's to the other.

Thanks in advance for any help you can provide.

#2 DGlass

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Posted 06 December 2005 - 11:31 AM

1. Am I correct in my selection?
I went to both speaker manufactures sites and there isn’t a lot of information available for their speakers. Anyways… using the 150 watt rating for the TP112 and the 90 watt rating for the GT1002 with one of each per side you would have a 240 watt, 4-ohm load. So you would be looking for an amp that could do about 240 watts per channel into a 4-ohm load (for 3db of headroom) and be in the range of 192 to 300 watts per channel. Since the power is shared between the two speakers, on a channel, they could both be getting 200 watts each with the XLS402. This would be fine for the TP112 as it is Peak Power rated for 300 watts but way to high for the GT1002 as I have a feeling that the 160 watt number you mentioned on the speaker is a Peak Rating. If you went with the XLS 202 you would be the other way low powered for the TP112 at 100 watts shared powered and good for the GT1002.

If you put identical speakers per channel of the amplifier The TP112s would present a 300 watt, 4 ohm load (amp power 300w- range of 240 to 375 w) to their amp channel while the GT1002 would be a 180 watt, 4 ohm load to their amp channel (amp power 180 w- range of 144w to 225w). Again the XLS 402 would be two much for the GT1002 but alright for the TP112.

In this case I would look at using two amplifiers to get a better power match. I would look at the XLS402 for the TP112 speakers (one per side) and the XLS202 for the GT1002. The XLS202 8-ohm per channel rating is only about 32 watts above the power range guidelines for the GT1002s I would first verify with the manufacture that this is alright.


2. Can these be hooked up parallel?
* You shouldn’t have a problem doing a parallel load with XLS amplifiers as long as you follow the power selection guidelines.

3. When I do hook them up parallel, can I just use the banana plug to connect to the amp with one speaker cable and then just plug another banana plug into the back of the previous plug? As long as I don't hook them up upside down, it seems like this would work. (Hopefully this makes sense)
*Using two stacked banana plugs works fine for paralleling speakers. You could also run one cable to a speaker and then jumper from one speaker to another.

4. For the highest quality sound, can I hook up one MTX and one Gemini to each channel or will I have to hook up both MTX's to one side and both Gemini's to the other.
*There are a few things to consider here: Are you running the system stereo? If you put one, of each speaker, per side than you will get the best imagery. If you have identical speakers on each amp channel than the two sides will sound different.
*However…. power requirements need to be considered also see response to Question 1.


#3 dembits

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Posted 06 December 2005 - 01:17 PM

Would it be possible to hook up the two smaller (90 watt) speakers to one channel and not turn that amp channel all the way up? I am trying to save money as muchas possible and I am not as worried about the speakers as I am about the amp. I got the speakers used for really cheap. Could this work for me and if it doesn't and it brings too much power to the speakers, would the amp get hurt?

#4 DGlass

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Posted 06 December 2005 - 02:34 PM

QUOTE(dembits @ Dec 6 2005, 01:17 PM)
Would it be possible to hook up the two smaller (90 watt) speakers to one channel and not turn that amp channel all the way up? I am trying to save money as muchas possible and I am not as worried about the speakers as I am about the amp. I got the speakers used for really cheap. Could this work for me and if it doesn't and it brings too much power to the speakers, would the amp get hurt?
View Post

The front panel level controls are input attenuators and not a Watt Knob. By turning the knobs up or down all you are doing is increasing or decreasing the amount of drive signal that is going to the amplifier. Amplifiers have a fixed amount of power they can put out. If you turn down the input level attenuators and give the inputs a large enough input signal you can still get full output of the amplifier.
As explained before there could be to much power available. The XLS is capable of delivering 400 watts to a 4 ohm load per channel. The means each speaker could have available to it up to 200 watts each. The GT1002 speakers are rated for 90 watts each. Keeping it turned down will not guarantee that you would not get peaks that could blow through and push the amp to full output or that someone wouldn't say it needs to be louder or shouldn't the knobs match and turn it up for you.
My recommendation is don't. But you can if you want to risk it. I would contact the speaker manufacture and ask them as well after all it's their speaker who would know it's capabilities better:)

#5 dembits

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Posted 06 December 2005 - 04:18 PM

Thanks. I will just have to bite the bullet and buy a lower powered amp for the smaller speakers.

#6 Bud Bolf

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Posted 07 December 2005 - 04:56 AM

Hi,
Forget this post.

Good Luck,
     Bud
PS. Here's a link to the Lounge, the Study Hall is at the upper Right.
         PSW Lounge

#7 DGlass

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Posted 07 December 2005 - 09:40 AM

Bud

I have to agree with you that mixing two different speaker boxes is not a good idea as they will not couple together correctly as well as the sonic differences between two different boxes not to mention phase and or polarity problems. The speakers he has- is what he has- and that is what the original posting asked for help with.

Yes, Dembits would be better off with (4) of the TP112 speakers than the GT1002 or even (4) matching boxes from a better name brand speaker manufactures that will have better characteristics, give better performance and have a higher resale. But sometimes you already have gear or the pocket book will not support this (especially for people just getting into the Biz.). I remember the days when I first started I used everything and anything I could afford ,or get my hands on, until I got to a place were I could move up and eventually could afford to go and buy my own Array system. Did these systems always sound good – No - but I learned a lot in those days stating out.

The Live Audio Forums is a good place to start and learn from others as well as getting good materials to read like the books and websites mentioned in previous postings of this form. But the comparison used in the analogy of the boat owner being an "idiot" is a little over the top. Yes, we as pros can be a little critical of others and their systems, sometimes, since we have access to the best toys, but let's not forget were we all started from.  smile.gif  smile.gif

#8 dembits

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Posted 07 December 2005 - 11:25 AM

Wow. As a wrote in the first post I am new and I only came on here to learn a little bit. Where did this thing go sour? I got four speakers for dirt cheap (gotta love craigslist), so the main goal is to try to make this work. I know that crown makes great amps, so when I decide to move up, I know that the heart of my system will be okay. That is why I am trying to get a good amp. Personally, I do not like the sound quality of the majority of the middle level speakers, and the MTX's surprisingly sounded the best for their price range. I am not really ready to go out and buy a huge system, just something small so that my friends and I can spin wax at local bars and house parties. I plan to use the MTX speakers as the mains and the Geminis for monitors. I have also considered getting a longer cable and putting one of the Geminis in the back of a room facing inward towards my setup to try to give it more of a surround sound vibe. I am not sure how that will sound, but I will have to experiment. From what it sounds like, most of you are professional sound techs, or just true hobbyists. That is fine, but what good does it do to berate a new guy? I spend all day writing how to books for notaries, and if you had a question on that, I would gladly help you out without making you feel like an idiot. And by the way, I don't know anything about speed boats, so I missed the analogy. Thanks!

R

#9 DGlass

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Posted 07 December 2005 - 12:51 PM

Crown's and my personnel apologies for the comments made by one of our forum members. As a semi-open forum we have no control, sometimes, over comments made by others before they are posted. Although technically correct it was out of place and over the top. We at Crown are proud to assist anyone in any way we can from beginners to professionals alike within the guidelines of the forum.

#10 Bud Bolf

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Posted 07 December 2005 - 08:54 PM

Howdy,
If I was over the top, then please accept my over the top apology!
It was around 4am.
I really meant for Constructive not Destructive advice.
If you think it was Destructive then I removed the Post.
Some points are:
You did not tell US what your application for these speakers was going to be.
In hind site both David and myself should have both asked you for that info first.
I will remember that in the future, my BAD!
In future posts, You could also help by being as forthcoming as
possible in exactly what your intentions are going to be, Equipment and need wise.
If your going to use the MTX's for your Mains and the Gemini's as monitors then let US know that. It really helps.
Also if you try and use one of the Gemini's for a rear room speaker, you may have delay issues, but you can give it a try.
I was ASSUMING that you were going to use these speakers together!
And you know what happens when you ASSUME something.

I did not want to see you going off and spending money in the
wrong direction, and have Salesman take advantage of you,
especially when you do not have a lot of money to play with!
Just because you got speakers dirt cheap does not mean
that you have to further complicate the issue by buying
the wrong Amplifiers based on the Speakers that you got cheap.
Amps are not.
If you know already that these speakers are not what you
are going to ultimately be using, then what happens when
you buy Amps based upon them, only to get a good deal
on the Speakers that you really want?
Hopefully the Amp choices that you make today, will still be good
with different speakers, tomorrow.
That's really all I was trying to convey, especially because you are new to all of this.
I wanted to lead you to study up a bit and really decide how your needs today
compare to your needs in the future.
Be an educated Sound Person, no more newbie.

  Not always is a Dirt Cheap deal the best deal in the long run.
I would hate to tell you to buy this or that amp and have you spend
good money and then when you fire up the "System" and wait
for WOW, instead it's Fizzle. Yet what's done is done.
Anyway,
To answer your original question:
  
1) I would put both MTX Speakers on one channel and you could Parallel
them with Bananas, or build a Rack panel with Speakons or 1/4" jacks.
The Specs for these are 150 Wrms, (the Power to speaker equation is 1.5 to 2X the RMS rating) that means that at 4ohms you could power these two paralleled cabs with between 450 Wrms (1.5x) to 600 Wrms (2x)
Therefore you would want a Power Amp that is rated at 450 to 600 Wrms per channel @ 4Ohms.
You should use a Crossover so Frequencies below 40 to 50hz will not be sent to the Cabs. The speakers are spec'd for 33hz to 22khz but I would probably not send anything below 40hz to them, maybe 50hz, depends on the speakers when you fire them up with good power!

2) The Gemini speakers would be on the other Channel, I did not find the specs for them but again assuming that the 90 watts is RMS, then
paralleled they would be 180 Wrms @ 4 Ohms.
With the 1.5 to 2x Power amp to speaker ratio that means you would want
between 270 Wrms (1.5x) to 360 Wrms (2x) @ 4 Ohms per Channel.

In summary I would think that a Power amp (such as the XLS402)
that is around 400 Wrms @ 4 Ohms per Channel would be a decent choice.
You would be 50 Wrms under the 1.5x on the MTX and 40 Wrms
above the 2x for the Gemini's. I'd back off the Gemini's Input just a bit under the MTX's.
If you go with an amp that has a Higher per Channel rating, (such as XS500)
then back off the Gemini's Input even more or they may go poof!

Another Scenario is that if you need to have different volume levels
on the Gemini's, because one is in the back of the room.
Then you need two Power Amps, but another problem is that
then each Speaker load is 8 Ohms.
At 8 Ohms the MTX's need an amp that is 225 Wrms @ 8 Ohms (1.5x)
to 300 Wrms @ 8 Ohms (2x) Still an XLS 402
The Gemini's need (if the 90 is rms) 135 Wrms @ 8 Ohms (1.5x) to
180 Wrms @ 8 Ohms per channel.

Again my apologies,
    Good Luck,
         Bud

PS. Let us know how it turns out.
I still say go check out the Pro Sound Web
it's a great place to learn.

#11 dembits

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Posted 09 December 2005 - 11:18 AM

Thanks for the info. I have read a few articles in the Study Hall and they are great. I plan to continue to read as much as possible to learn what I can. I got a smaller amp that will work for the monitors and will be getting the XLS 402 to run the MTX speakers. I was also planning on getting a case where I could stack my dual deck cd player and both amps. Will there be a problem with stacking these components on top of each other  or is there anything that I should look out for?

#12 DGlass

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Posted 09 December 2005 - 01:02 PM

QUOTE(dembits @ Dec 9 2005, 11:18 AM)
Thanks for the info. I have read a few articles in the Study Hall and they are great. I plan to continue to read as much as possible to learn what I can. I got a smaller amp that will work for the monitors and will be getting the XLS 402 to run the MTX speakers. I was also planning on getting a case where I could stack my dual deck cd player and both amps. Will there be a problem with stacking these components on top of each other  or is there anything that I should look out for?
View Post

I general there shouldn't be a problem with stacking them. In practice I usually leave at least one rack space between an amp and another piece of electronic gear that is of a lower signal source. This is to avoid any unforeseen electromagnetic interference from power transformers and such.

#13 Bud Bolf

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Posted 09 December 2005 - 05:23 PM

QUOTE(DGlass @ Dec 9 2005, 02:02 PM)
QUOTE(dembits @ Dec 9 2005, 11:18 AM)
Thanks for the info. I have read a few articles in the Study Hall and they are great. I plan to continue to read as much as possible to learn what I can. I got a smaller amp that will work for the monitors and will be getting the XLS 402 to run the MTX speakers. I was also planning on getting a case where I could stack my dual deck cd player and both amps. Will there be a problem with stacking these components on top of each other  or is there anything that I should look out for?
View Post

I general there shouldn't be a problem with stacking them. In practice I usually leave at least one rack space between an amp and another piece of electronic gear that is of a lower signal source. This is to avoid any unforeseen electromagnetic interference from power transformers and such.
View Post


Hi again,
  I have a Gator Rack that has a CE4000 on the bottom, a CE2000 above
the CE4000 and then a Sennhieser Digital wireless receiver
(for my Bass Guitar) above the CE2000. I have had no problem at all.

I would say that before you get the rack go ahead and
stack the equipment just as you would in the rack, and see if there
is any problems.
If your afraid of scratching the outer cases, just lay a towel between the Amps and CD player.
If all goes well, then get yourself a rack to hold it all.

Ya know, better than bananas, and you can't pull them out, is using
Speakons at the Amp and 1/4" at the Speakers.
You can build them or buy them. I'd use 12ga wire.
A good place to check out these items is at Parts Express,
the link is here: Parts Express

#14 Bud Bolf

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Posted 09 December 2005 - 05:32 PM

Hi again,
  I have a Amp Rack that has a CE4000 on the bottom, a CE2000 above
the CE4000 and then a Sennhieser Digital wireless receiver
(for my Bass Guitar) above the CE2000. I have had no problem at all.

I would say that before you get the rack, go ahead and
stack the equipment just as you would in the rack, and see if there
is any problems.
If your afraid of scratching the outer cases, just lay a towel between the Amps and CD player.
If all goes well, then get yourself a rack to hold it all.

Ya know, better than bananas, and you can't pull them out, is using
Speakons at the Amp and 1/4" at the Speakers.
I did eventually changed out my speakers to Speakons as well.
You can build them or buy them, 12ga wire is pretty good for
up to 75 feet or so.
A good place to check out these items is at Parts Express,
the link is here: Parts Express


  Later,
     Bud