Bridging tops

[Javlingames]

Hi, I have a QSC PLX3402 AMP Running 2 nexo ps15's. The ps15's are 8 ohms so im not getting full use of the power amp. If I Bridge the Amp and link the speakers together I can get more power to them BUT when im doing a 60's set will I lose vocals?

[DJ Jules]

Hi, I have a QSC PLX3402 AMP Running 2 nexo ps15's. The ps15's are 8 ohms so im not getting full use of the power amp. If I Bridge the Amp and link the speakers together I can get more power to them BUT when im doing a 60's set will I lose vocals?

Short answer is yes, you can do it. If you ran the amp in bridge mode and connected the speakers to the amp in parallel (presenting a 4ohm load), you'd be driving it at to it's max (3kw!)

Why would you lose the vocal's when you're doing a 60's set? Are the vocals all in one channel? If so, I'm not sure how this particular amp handles this (i.e. if the amp sums L and R inputs to produce the signal for bridging). I'd have to read the manual to do that - something you could do :D

Julian

[Javlingames]

Short answer is yes, you can do it. If you ran the amp in bridge mode and connected the speakers to the amp in parallel (presenting a 4ohm load), you'd be driving it at to it's max (3kw!)

Why would you lose the vocal's when you're doing a 60's set? Are the vocals all in one channel? If so, I'm not sure how this particular amp handles this (i.e. if the amp sums L and R inputs to produce the signal for bridging). I'd have to read the manual to do that - something you could do :D

Julian

Hi Jules thanks, yes in 60's songs that were recorded in mono, you tend to get vocals one side, in particular with tamla motown. I will investigate , thanks for your help.

[DJ Jules]

Hi Jules thanks, yes in 60's songs that were recorded in mono, you tend to get vocals one side, in particular with tamla motown. I will investigate , thanks for your help.

I did think that there's probably other ways you can solve this if the amp doesn't sum the two signals depending on the kit you have upstream of the amp (e.g. Mixer, Software, etc). Some mixers can be switched to mono, as can some decks and software.

Julian

[Javlingames]

I did think that there's probably other ways you can solve this if the amp doesn't sum the two signals depending on the kit you have upstream of the amp (e.g. Mixer, Software, etc). Some mixers can be switched to mono, as can some decks and software.

Julian

Yes my serato can be switched to mono. Maybe that's my answer

[Corabar Steve]

If something is in mono the whole thing goes to both stereo channels usually

[DJ Jules]

Yes my serato can be switched to mono. Maybe that's my answer

I would expect that'd probably do what you'd want (i.e. sum L and R channels and deliver the sum through both L and R outputs). Only one way to tell... try it :D

Julian

[Javlingames]

Thanks all

[Excalibur]

If something is in mono the whole thing goes to both stereo channels usually

But then they wouldn't be stereo, would they? :p:D:D


OK, from the Nexo manual:
Recommended Amplifiers 550 to 1200 Watts into 8 Ohms for 1 x PS15 per channel
PS SERIES MANUAL REV3 10/10/05
1000 to 1800 Watts into 4 Ohms for 2 x PS15 per channel

The QSC claims 800 watts at 8 ohms. Spot on, I'd say.

Bridged, it says 1700 per cab ( 3400 into the two in parallel ). Not good.

[DJ Jules]

But then they wouldn't be stereo, would they? :p:D:D


OK, from the Nexo manual:
Recommended Amplifiers 550 to 1200 Watts into 8 Ohms for 1 x PS15 per channel
PS SERIES MANUAL REV3 10/10/05
1000 to 1800 Watts into 4 Ohms for 2 x PS15 per channel

The QSC claims 800 watts at 8 ohms. Spot on, I'd say.

Bridged, it says 1700 per cab ( 3400 into the two in parallel ). Not good.

I did wonder about that - the blurb on their website says something about being able to take 2kw each though. Their salesy data sheet (http://nexo-sa.com/attachments/products/27/nexo_ps15-r2_datasheet.pdf) says 1-2kw as well.

It did strike me as having incredibly high nominal power handling capability. Where's the manual to?

Julian

[Excalibur]

I did wonder about that - the blurb on their website says something about being able to take 2kw each though. Their salesy data sheet (http://nexo-sa.com/attachments/products/27/nexo_ps15-r2_datasheet.pdf) says 1-2kw as well.

It did strike me as having incredibly high nominal power handling capability. Where's the manual to?

Julian

this is the one I found. (http://nexo-sa.com/attachments/products/46/ps-series-manual.pdf)

[Javlingames]

You can drive them with as much wattage as you like. If you have the nexo controller set up correctly, they won't blow. The controller has sense lines attached to the speaker output terminals on the amp.

They say the nexos like a lot of power to make them truly sing.

[DJ Jules]

You can drive them with as much wattage as you like. If you have the nexo controller set up correctly, they won't blow. The controller has sense lines attached to the speaker output terminals on the amp.

I hadn't come across the controller bit yet. Clever idea, DSP to optimise the sound for the cabs, active crossover and protection, all in one box.


They say the nexos like a lot of power to make them truly sing.

They told me that about the JBL's I bought as well. Personally I always thought that more power just made them shout or scream, rather than sing, but then the JBL's were £400 a pair, not £4k! :D

Julian

[Corabar Steve]

But then they wouldn't be stereo, would they? :p:D:D


No, they'd be a left hand mono channel with the whole track playing & a right hand mono channel with the whole track playing SMARTARSE!:P

My point was a mono track would not have vocals on one channel & music on the other. (It would also be quite unusual for a stereo track to do that)

[Excalibur]

You can drive them with as much wattage as you like. If you have the nexo controller set up correctly, they won't blow. The controller has sense lines attached to the speaker output terminals on the amp.

They say the nexos like a lot of power to make them truly sing.

So let me get this right. You've got an amp and cabs which appear to be perfectly matched as they are, you want to couple them up so that you get maximum power into the management system which then throttles it back so that the cabs get roughly what they were getting in the first place, and your amp runs into a two ohm load per channel, thus ensuring its fans get a really good workout to disipate the heat produced? :confused:

Leave well alone would be my advice. I don't expect you to find any noticeable improvement in volume, sound quality or definition, and I do expect you to find problems with heat. How much more volume do you need out of cabs which can produce 136Db or so?

[Javlingames]

So let me get this right. You've got an amp and cabs which appear to be perfectly matched as they are, you want to couple them up so that you get maximum power into the management system which then throttles it back so that the cabs get roughly what they were getting in the first place, and your amp runs into a two ohm load per channel, thus ensuring its fans get a really good workout to disipate the heat produced? :confused:

Leave well alone would be my advice. I don't expect you to find any noticeable improvement in volume, sound quality or definition, and I do expect you to find problems with heat. How much more volume do you need out of cabs which can produce 136Db or so?

Yes Nexo recommend 600 to 1200 watts (I think) so at 8 ohms they are getting 700 watts on my amp, which is fine. Im happy. But if my sound was improved by bridging and getting extra power to the tops I would consider it. Bridging is just an idea at this point .

[Javlingames]

I hadn't come across the controller bit yet. Clever idea, DSP to optimise the sound for the cabs, active crossover and protection, all in one box.



They told me that about the JBL's I bought as well. Personally I always thought that more power just made them shout or scream, rather than sing, but then the JBL's were £400 a pair, not £4k! :D

Julian

JBLS's are a bit shouty. The controllers are very clever pieces of kit. You just turn your amps right up and the controller does the rest. Pretty pricey stuff but I do go for 2nd hand gear, especialy nexo. £4k for a mobile disco is a bit OTT .

[addoaddo]

Although you could do it I think it would be a mistake as you have a high chance to blowing the amplifer. 4ohm as a load for a bridged amp is the same as a normal amp running at 2ohm. Some can do it but it puts a lot so stress on the components. I used to have two crown amps that I used for the bass bins and had the same idea 1300W bridged mode. One night 1 amp went dead, a couple of weeks later on a single night I lost both bass amps. In a space of 3 weeks I had lost 3 amps. During the last 10 years I have only lost one other amp. I now keep all the amps running at a min of 4ohm load and not bridged.

[Javlingames]

Although you could do it I think it would be a mistake as you have a high chance to blowing the amplifer. 4ohm as a load for a bridged amp is the same as a normal amp running at 2ohm. Some can do it but it puts a lot so stress on the components. I used to have two crown amps that I used for the bass bins and had the same idea 1300W bridged mode. One night 1 amp went dead, a couple of weeks later on a single night I lost both bass amps. In a space of 3 weeks I had lost 3 amps. During the last 10 years I have only lost one other amp. I now keep all the amps running at a min of 4ohm load and not bridged.

Yes I have heard that amps don't really like it, think I will just keep it simple. Sound like the best option is to add another 2 tops bringing it down to 4 ohms. Don't think I will need 2 more , especially with these babies