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Lost in sub ... with DRPA +

valverecordvalverecord Posts: 6
edited September 2014 in PA Connectivity
In Google

Hello I am new to this forum.
Wear over a year working with a DRPA +, and everything has been fine so far.
Due to technical requirements the PA + has always been at the rack of steps on stage.
configuration:
High- (L and R)
Middleton (L and R)
Low- mono.
The team is always perfect.
The last weekend, (as I had sufficient channels in hoses) + put the PA on the table (FOH) to have a more direct device control. What was my surprise to notice a loss of 60% or even 70% in the bass. I tried 3 different channels, two hoses for the shipping Low signal loss and always the same, however the High and Middle signal going well.
I replaced the rack PA + stages on stage and all was well again.
Is it possible that the hose of 25 meters, is responsible for this loss?
Incidentally, I did change to FOH with the same program without changing any settings.
On Saturday we have another performance, whether you could help, I would be grateful.
Thank you.
a greeting
Juan Carlos.
Spain


Hola soy nuevo en este foro.
Llevo más de un año trabajando con un DRPA +, y todo ha estado bien, hasta ahora.
Por necesidades técnicas el PA+ siempre ha estado en el rack de etapas en el escenario.
Configuración:
High-(L y R)
Middle-(L y R)
Low- en mono.
El equipo siempre va perfecto.
El fin de semana pasado, (como ya disponía de canales suficientes en las mangueras) puse el PA+ en la mesa (FOH), para tener un control más directo del aparato. Cuál fue mi sorpresa al notar una pérdida del 60% o incluso el 70% en los graves. Probé con 3 canales diferentes, en dos mangueras, para el envío de la señal Low, y siempre la misma perdida, sin embargo la señal High y Middle van bien.
Volví a poner el PA+ en el rack de etapas en el escenario y todo fue bien otra vez.
¿Es posible que la manguera de 25 metros, sea la responsable de dicha pérdida?
Por cierto, el cambio a FOH lo hice con el mismo programa y sin cambiar ningún parámetro.
El sábado tenemos otra actuación, si pudierais ayudarme, os estaría agradecido.
Gracias.
Un saludo
Juan Carlos.
España

Comments

  • Options
    DraDra Posts: 3,777
    Swap the low & high connections at the PA+ and amps. Does the problem change or remain the same?

    DRA
  • Options
    valverecordvalverecord Posts: 6
    Neither has happened to me, I have always believed that the -10 dBV, +4 dBu, affected only the input and not the output.
  • Options
    DraDra Posts: 3,777
    I am talking about the cables at the outputs on the PA+ and the cables at the inputs of the amps.

    DRA
  • Options
    valverecordvalverecord Posts: 6
    As I explained in my first post, I tried different cables and hose, with the same result, in fact we have two Multi hoses, and tried with both and was equal.
  • Options
    DraDra Posts: 3,777
    Again. I am not saying to try new cables. I am saying to swap the connections so tht the cables that are working fine for the highs are being used for the lows and the cables for the lows will be used for the highs. Does the problem remain with the Low output?
    It could be a capacitance problem causing a loss of low frequency information due to the distance. If so, the solution would then be to purchase a higher quality cable dedicated to the sub signal. Another solution would be to increase the sub's (low) gain in the x-over section to compensate for the loss.

    DRA
  • Options
    valverecordvalverecord Posts: 6
    Understood, no, I did not try that all cables are igales is 32 pairs hose, just connect da 1, 2 .... that 30 ... etc. Thank you for your trouble. I can not prove anything until Saturday which is the day of the concert, all the material is loaded into the truck.
  • Options
    DraDra Posts: 3,777
    My best guess is that you will need to increase the lows gain in the cross-over to balance the outputs.

    DRA
  • Options
    valverecordvalverecord Posts: 6
    I had thought about it, I'll have to readjust the whole team.
    Thanks for your interest.
    a greeting
  • Options
    byaceybyacey Posts: 16
    Dra wrote:
    Again. I am not saying to try new cables. I am saying to swap the connections so tht the cables that are working fine for the highs are being used for the lows and the cables for the lows will be used for the highs. Does the problem remain with the Low output?
    It could be a capacitance problem causing a loss of low frequency information due to the distance. If so, the solution would then be to purchase a higher quality cable dedicated to the sub signal. Another solution would be to increase the sub's (low) gain in the x-over section to compensate for the loss.

    DRA
    Excessive capacitance will roll off the high frequency content long before affecting the low frequency in any way. However, low impedance balanced line are generally unaffected by capacitance; you can run thousands of feet without much concern.

    It is mentioned the sub(s) are mono. Is there more than one sub feed out of the driverack, and how many sub amplifiers? If so, it could be a phase reversal on one of the sub lines, even though they are mono.

    Check the cables that are normally used at the stage location.Perhaps one cable is wired out of phase, and one speaker is connected out of phase to the amp to correct the phase issue created by the reversed line feed cable. If this is the case, using two proper in phase cables to drive the subs will create an out of phase condition on one sub.
  • Options
    DraDra Posts: 3,777
    Assuming the Google translator is accurate, the only difference (as I read it) is the insertion of the snake into the path. Like you said, that alone should not cause the result achieved. This is an odd one. There has to be more.

    DRA
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