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Author Topic: Replace Lab1300c by Camco DX24 on sub: worth it ?  (Read 6504 times)

Nicolas Poisson

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Replace Lab1300c by Camco DX24 on sub: worth it ?
« on: August 31, 2012, 08:32:53 AM »

Hi,

I currently use a Lab.Gruppen 1300c on a single  EAW FR250z sub. The amp is set up in bridge mono mode on a 4 ohm load (thus virtually 2 ohms per side).
The sound is not bad, but I find it lacks "punch".

I was thinking about replacing it by a 2nd hand Camco DX24, set up in parallel mode (not bridge), with each channel seeing an 8 ohm load. Weight is not important. Moreover, I could keep the DX24 - set up in stereo - if I were to buy a second FR250z in the future.

Has anybody tried the DX in parallel mode on subs ? Has anybody compared DX and old Labs on subs ? Is it worth replacing the Lab by the Camco ?
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Nicolas Poisson

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Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #1 on: September 13, 2012, 03:04:11 AM »

I reply to myself, since I did buy a DX24.

I first set up the DX24 in stereo, connecting my single sub FR250z on one channel. Sound was more punchy than with the lab1300c bridged mono.
I then set it up in parallel mono. This way each channel virtually sees an 8 ohm load (the FR250z is 4 ohms) and the available power increase to 1920W. I could not hear any significant difference compared to stereo/1 channel.
Tests were made playing back a CD, I did not had the chance to use the new amp in live show yet.

OK, I had read before that running an amp on 2-ohm load per channel is generally a bad idea, even with good amps, and especially on subs. I tried, I compared, I am now convinced too. May this post convince other people.
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Mac Kerr

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Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #2 on: September 13, 2012, 08:52:47 AM »

I then set it up in parallel mono. This way each channel virtually sees an 8 ohm load (the FR250z is 4 ohms) and the available power increase to 1920W. I could not hear any significant difference compared to stereo/1 channel.

It's not surprising that you didn't hear a difference, since there was no difference. Parallel mono just sends the channel 1 input to both channels of the amp, it does not change the amp channel outputs at all.

Mac
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Nicolas Poisson

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Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #3 on: September 13, 2012, 11:07:22 AM »

Hi Mac,

Note that the "parallel mono" mode of the Camco DX is the same as that of the Crowns: it parallels both inputs and outputs. You have to add a "shorting plug" (a 4 pole speakon plug with 1+/2+ shorten) on output 2. You connect the speaker to the other output (but I guess it works exactly the same if you switch outputs). This is different from the Lab.Gruppen "tandem mono" which is exactly what you describe, in which case you shall never shorten positive outputs from what I read.
This feature was one reason that made me choose the DX24, because it allows me to use both channels on my current setup (mono), and would still be acceptable if I were to buy a second sub (switching to a full stereo setup).

My understanding is that it does not change the amp gain (exactly like two 1.5V batteries in parallel still deliver 1.5V), but each channel of the amplifier provides half of the total current. Virtually a 4 ohm load is seen as 8 ohm by each channel, improving the damping factor and total power (increasing from 2x1400W/4 ohm to 1x1920W/4 ohms for the DX24). This why I thought I could expect slightly better sound on a subwoofer in parallel mono. But this was not the case.
- Either I did not ran it hot enough
- or the amp is not bad enough to suffer on a 4 ohm load
- or actually there is a difference but my ears are not trained enough, which could happen more often than my ego can recognize :-[
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RYAN LOUDMUSIC JENKINS

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Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #4 on: September 13, 2012, 01:55:46 PM »

Hi Mac,

Note that the "parallel mono" mode of the Camco DX is the same as that of the Crowns: it parallels both inputs and outputs. You have to add a "shorting plug" (a 4 pole speakon plug with 1+/2+ shorten) on output 2. You connect the speaker to the other output (but I guess it works exactly the same if you switch outputs). This is different from the Lab.Gruppen "tandem mono" which is exactly what you describe, in which case you shall never shorten positive outputs from what I read.
This feature was one reason that made me choose the DX24, because it allows me to use both channels on my current setup (mono), and would still be acceptable if I were to buy a second sub (switching to a full stereo setup).

My understanding is that it does not change the amp gain (exactly like two 1.5V batteries in parallel still deliver 1.5V), but each channel of the amplifier provides half of the total current. Virtually a 4 ohm load is seen as 8 ohm by each channel, improving the damping factor and total power (increasing from 2x1400W/4 ohm to 1x1920W/4 ohms for the DX24). This why I thought I could expect slightly better sound on a subwoofer in parallel mono. But this was not the case.
- Either I did not ran it hot enough
- or the amp is not bad enough to suffer on a 4 ohm load
- or actually there is a difference but my ears are not trained enough, which could happen more often than my ego can recognize :-[

I use the parallel mono function on my Camco Vortex 6 amps all the time.  I do not however have to short any of the outputs together on mine.  Keep in mind that since the gain remains the same, for you to get full output and notice any difference than you need to send a hotter signal to the amp.  If you send a +4dBu signal to a 1000 watt amp set for 32dB gain then you will get the same output as you would by sending that same +4dBu signal to a 10,000 watt amp with the gain set for 32dB.  Just having an amp capable of having more output is not going to just make it louder, you have to use the extra capacity to get louder.

At the same time,  If you are just gaining a couple hondred watts of potential power by the swtich 1560 Watts to 1920 watt then I would be very surprized if you could tell the difference anyways.  The camco does not seem to be rated for 4ohm Bridged operation so that is out of the question.
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Nicolas Poisson

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Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #5 on: September 14, 2012, 02:31:37 AM »

Concerning the shorting plug, I just followed the manual. I guess Camco has improved the design in the Vortex series. Indeed, the DX is already an improvement over the older DL series which only had the "bridge" mode, no "parallel".
The DX48 accepts 2 ohm/channel, but DX12 and DX24 do not.

I thought the simple fact that the damping factor doubles could have improved the sound, but it did not and you seem to confirm that it is usually not audible.
« Last Edit: September 14, 2012, 02:33:59 AM by Nicolas Poisson »
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ProSoundWeb Community

Re: Replace Lab1300c by Camco DX24 on sub: worth it ?
« Reply #5 on: September 14, 2012, 02:31:37 AM »


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