# Hooking up second pro amp.



## canaris (Dec 13, 2006)

I want to use 2 amps to power my 2 pairs of Tempests ... What are some of the better ways to split the pre-sub out from my HTR without weakening the signal. I also have a BFD in the signal path.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Well, if you have a BFD in the signal chain, you'll have to split after that point. A common "y" splitter works as good as anything else and doesn't appreciably weaken the signal. Even if it does - that's why amps have gain controls.

Regards,
Wayne


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## thxgoon (Feb 23, 2007)

With the BFD in mono mode doesn't it take one input and output on both channels? For some reason I though it did.


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## Wayne A. Pflughaupt (Apr 13, 2006)

There's no such thing as "mono mode" on the BFD, but you did jog my memory about something: It's possible that the signal would be present on both the balanced and unbalanced outputs of the channel you're using. It's not uncommon to find this with balanced gear. Can't hurt to try... 

Regards,
Wayne


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## thxgoon (Feb 23, 2007)

Maybe it's not called the mono mode... but I swear I remember setting something up so that the calibrations apply to both channels and not just one. I'll have to look when I get home. And I do believe you are correct about outputting both 1/4 and XLR. Infact, on my setup I'm running in 1/4" and out XLR, so I'd imagine it's working on both


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## canaris (Dec 13, 2006)

So I go out from my HTR into the BFD and then split it to the two amps.... 

What if I want to run the amps in normal stereo configuration which needs the signal to be split in 4?


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## Wayne A. Pflughaupt (Apr 13, 2006)

thxgoon said:


> Maybe it's not called the mono mode... but I swear I remember setting something up so that the calibrations apply to both channels and not just one. I'll have to look when I get home.


Yeah, IIR you can set it to where any filters you enter are assigned to both channels.


> And I do believe you are correct about outputting both 1/4 and XLR. Infact, on my setup I'm running in 1/4" and out XLR, so I'd imagine it's working on both


Yup, typically if you can find a block diagram you'll find that both the inputs and outputs are tied togther.

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

canaris said:


> So I go out from my HTR into the BFD and then split it to the two amps....
> 
> What if I want to run the amps in normal stereo configuration which needs the signal to be split in 4?


There's no need to run the amps in stereo if you're feeding it the same mono signal to each channel. Switch them to parallel mode, so that one input will feed both channels.

Regards,
Wayne


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## Mike Cason (Mar 17, 2007)

Hi Wayne,

Good to meet you at the audition....:T

That's how I've got my two pro amps set up in my system, paralled to a single output. I wired my 4 voice coils on each sub's twin drivers in series for an 8 ohm load and now I don't worry about blowing them as they probably don't see much more than 900 watts at the low freqs. (Soundsplinter RLP 15s).

Both of my QSC 1450s have been set up to mono and you heard how great they sound. I've got twin sub outs on my Rotel, but they are wired together inside the rotel, basically the same configuration as a "Y" connector. I've also used the "Y" connector to a single sub output on the Rotel and saw no difference.

Come by when you can,
Mike


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## canaris (Dec 13, 2006)

I got 4 drivers with dual voice coils in each... My pro amps are the same brand but different models.... Right now I am not taking advantage of the amps power cause I have the 4 drivers wired as 8 ohm pairs which only gives 250 watts to each driver. The amp can do 750 watts per side in 4 ohms or 2200 watts bridged to 4 ohms. I wanted be able to power 1 pair of subs with each amp in a 4 ohm stereo configuration. Any one follow what I am saying cause I think I just lost myself?


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## Mike Cason (Mar 17, 2007)

canaris said:


> I got 4 drivers with dual voice coils in each... My pro amps are the same brand but different models.... Right now I am not taking advantage of the amps power cause I have the 4 drivers wired as 8 ohm pairs which only gives 250 watts to each driver. The amp can do 750 watts per side in 4 ohms or 2200 watts bridged to 4 ohms. I wanted be able to power 1 pair of subs with each amp in a 4 ohm stereo configuration. Any one follow what I am saying cause I think I just lost myself?


You should just bridge each of the amps and the amps will see the 8 ohm load. You won't be seeing 2200 watts to your 8 ohm speakers. This should work fine. If you have a higher wattage amp than the 1450s that I have, just be sensible with your gains. You should look into getting the Reckhorn B-1 equilizer (85 bucks from CSS) or something similar for better control and subsonic frequency protection and high pass filter. It also has gain control and bass boost down to 20 hz.


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## canaris (Dec 13, 2006)

Mike, I already have a BFD so I don't think the Reckhorn will benefit me more.


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## Mike Cason (Mar 17, 2007)

canaris said:


> Mike, I already have a BFD so I don't think the Reckhorn will benefit me more.


canaris

You should be in good shape with the BFD. I found by turnining off all of my filters and clip limiters on the amps and using the B-1's controls, I'm able to get the full benefit of the amps capabilitities. I get all of the lows the amps can produce now.

Crank 'em up~~~~:T

Mike


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hi Mike,

Yes that was a great get-together! Thanks for hosting us.



canaris said:


> Right now I am not taking advantage of the amps power cause I have the 4 drivers wired as 8 ohm pairs which only gives 250 watts to each driver. The amp can do 750 watts per side in 4 ohms or 2200 watts bridged to 4 ohms.


Something doesn't sound right there. Typically an amp will be doing good to double its power between 8 ohms and 4 ohms (many can't), but yours triples power, from 250 to 750 watts?



> I wanted be able to power 1 pair of subs with each amp in a 4 ohm stereo configuration.


Probably won't be able to do that with these drivers, as that would require drivers with (logically) 4-ohm voice coils

Regards,
Wayne


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## Mike Cason (Mar 17, 2007)

Hey Wayne....:1eye:

UPDATE:...I see you are adressing Canaris's post, but this is good information for him as well.....



You got me curious....so I just checked with QSC on their specs to make sure I didn't go wrong as it's been a couple of years since I've looked at it. 

My wife blew up my drivers once when she switched movies and I had each driver hooked up to a separate bridged QSC 1450 back when I only had one sub. They were seeing 1450 watts at 4ohms to each driver. That's when I was using the Y connector so the timing would be exact to each amp.

I had to get a couple more drivers from Mike.....

I removed one of the amps and hooked all my voice coils together in series to present an 8 ohm load to the amp and used a single QSC in the bridged mode. (I ordered two more drivers and built a second sub because we couldn't just let that other amp sit there not working.)

After I just read your post, I double checked QSC's specs on that type of installation and their specs say that with the 1450 amp, bridged to mono, the output would be 800 watts between 20hz and 20,000 hz. at 8 ohms. They have a handy chart showing the different outputs from their different models.

I went with this setup because 800 watts is plenty for the RLP 15s with peaks and clips.

Here is the link....http://media.qscaudio.com/pdfs/Specifications/RMX_spec.pdf

Mike


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## canaris (Dec 13, 2006)

> Something doesn't sound right there. Typically an amp will be doing good to double its power between 8 ohms and 4 ohms (many can't), but yours triples power, from 250 to 750 watts?



Sorry.... they way I explained it I mixed you up.... What I meant to say is.... right now I got 4 dual 8 ohm VC subs that I am powering with a Crest CPX 2600 pro amp. I have set up the subs at 8 ohm pairs so the amp is only delivering it's rated 500 amps at 8 ohms = 250 per driver. The amp is capable of putting out 900 watts in 4 ohm stereo or 1800 in bridged 4 ohms. Now I have a second amp and I want to use it to split the drivers up and power 2 drivers per amp .I want to be able to send at least 600 watts to each driver since they are rated for 750 watts and get the somewhat the full benefit of the amps. Of course I would be careful with the gain knobs.LOL!


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## Mike Cason (Mar 17, 2007)

Take two of your drivers and parallel the 8 ohm coils for a 4 ohm load. Do the same for the other two drivers. Use a "Y" splitter and send the same signal to both sides of the amp's input and you should be. That gives you a pair drivers with 4 ohm loads to L & R of your stereo using the same signal.

Overamping is better than underamping and I prefer this but unfortunantly, I had the gains set to full when from the last movie I had been watching. Throttle them back about a third on your gains, and you should be fine. You have less chance of clipping with a higher powered amp. That's why I had a single bridged 1450 throwing that much power into a 1000 watt driver, but I thought I was in control of the gains. I forgot to set them back after the night before. Gosh, it's always so easy to blame the wife!

Mike


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## Wayne A. Pflughaupt (Apr 13, 2006)

Mike Cason said:


> Take two of your drivers and parallel the 8 ohm coils for a 4 ohm load. Do the same for the other two drivers. Use a "Y" splitter and send the same signal to both sides of the amp's input and you should be. That gives you a pair drivers with 4 ohm loads to L & R of your stereo using the same signal.


It also leaves him with a vacant amplifier... 

Again, no need to use a "y" - just switch the amp to Parallel mode. 

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

See Pg. 10 of the manual...

http://media.qscaudio.com/pdfs/manuals/RMX_User_Manual.pdf

Regards,
Wayne


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## Mike Cason (Mar 17, 2007)

It sure does leave him a spare amp! 

I didn't even think of the parallel option. That's the way I hooked mine up, but after a couple of years after setting mine up, I forgot I used that option. 

Take care Wayne... :T


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## canaris (Dec 13, 2006)

Is it possible my Crest amps have no setting for parallel hookup? 

All I see is 'bridged' and 'stereo'. 

CREST CPX 2600) 

and crest CA6 :scratch:


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## Mike Cason (Mar 17, 2007)

canaris said:


> Is it possible my Crest amps have no setting for parallel hookup?
> 
> All I see is 'bridged' and 'stereo'.
> 
> ...


I'll check in in the a.m. when I come out to my office and if you haven't received a reply by then, I'll check it out for you. It's been a long day for me. If you have a manual, read the dip pin switch setting information and see if that option is available. I don't know that model and it may not have those switches which would be mounted on the back. A pair of those switches may say "Parallel on or off". If you see that, then yes you can. You may leave the right gain on full all the time and the left gain will control both channels together.

Mike


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## Wayne A. Pflughaupt (Apr 13, 2006)

The CPX doesn't have a Parallel mode, but all the inputs - XLR, 1/4" and barrier strip - are paralleled internally. (manual, pg. 19) So, you can use say, an XLR cable to Channel A, then use a short TRS cable between Channel A and Channel B. You could also simply use jumper wires (with spade lugs) to make the connection between Channel A and Channel B. 

The CA 6 has a parallel switch on the back (manual pg. 11)

Regards,
Wayne


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## canaris (Dec 13, 2006)

The Ca6 is an older model I have ...it has an internal jumper that says 'stereo' and 'bridged'.. nothing else... he is a pic of the back... 










the CPX


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## brucek (Apr 11, 2006)

> it has an internal jumper that says 'stereo' and 'bridged'


When you bridge an amplifier, there will be one (of the two) input channels that is specified as the single input to use.

brucek


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