Using autosound linedriver for HT sub amps

Discussion in 'Archived Threads 2001-2004' started by Kenny WH, Apr 12, 2002.

  1. Kenny WH

    Kenny WH Stunt Coordinator

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    I've got a Phoenix Gold PLD-1 linedriver I used back when I was dabbling in autosound competitions and was wondering if I could use in my theater to drive my sub amps.

    I currently have a Samson S1000 driving dual SVS Ultras and another amp driving a 10 unit tt array. At first I just had the Samson/SVS running off the sub out on my Denon 5800, but when I y'd the sub out and added the second amp/tt I noticed I had to turn up the level on the sub out to get the Samson/SVS to the level they were before.

    To make a long story short, would using the linedriver powered with an AC to DC converter be of any benefit?

    I know pro-sound style amps require more input voltage than true consumer style amps and thats why I'm asking. The PLD-1 has adjustable gains so It's very flexible when it comes to matching input voltages.

    Thanks,

    Ken
     
  2. jeff lam

    jeff lam Screenwriter

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    It would probably work but will it pass a clean signal? That's the only thing I'd be worried about. That and the AC-DC converter. With the system you have you might be better off going with the SVS Black Box.

    I use an Ebtech Line Level shifter and I gain about 8db. It's a passive design so no power supply or added noise. It's just an impedance matcher.
     
  3. James Mudler

    James Mudler Stunt Coordinator

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    Kenny,

    We are in the same boat. I have a couple of PLD-1 and TBA-T's laying around was wondering the same thing. I have not had the time to install it yet. I already have a 12v power supply in my rack so it should be pretty quick.

    Either way whoever does it first....lets post the results.
     
  4. Ken Shiring

    Ken Shiring Agent

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    Guys, be careful. Driving car amps in your house is not as easy as finding a 12v supply.
    The big fat reason is : wattage. I'm guessing these amps are going to pump out 100+ watts, which means that the power supply driving these suckers has to source probably around 167 W (for a low efficiency of 60% found in class AB amps). 167 W * 1.4 (AC/DC conversion factor) is around 234 VA.
    So you would need a transformer with 234 VA *per channel* to drive these amps. Transformers with that kind of rating are big and heavy, and you will need to throw in a bunch of other stuff to keep your supply from blowing up. You need at least one high power bridge rectifier, a slew of large caps, and large gauge wire to handle the current.
    The point I'm making here is that this is not a simple effort. It would cost you a similar amount of money just to go out and buy new 120V amps [​IMG] .
     
  5. Ken Shiring

    Ken Shiring Agent

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    Whoops. I just realized you guys weren't talking about amps. I haven't heard of what a 'line driver' is, but I'm guessing it is some sort of small redrive device? Don't know what kind of power requirements it needs, but anything in the 100 mA category can be sourced from a wall transformer.
     
  6. jeff lam

    jeff lam Screenwriter

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    Ken,
    Ya not much current is required to run one or these. It's more like the current draw of an electronic crossover or an eq. Not power amps. You're right though about needing a bug huge expensive transformer to power an amp. We get many of those questions every once in a while too. Everyone wonders why we just point them to the PE 250W plate amp??? Go figure![​IMG]
     
  7. Marc Bodin

    Marc Bodin Extra

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    The line driver will have a very high s/n ratio, probably in excess of 100 db. It will not affect the quality of the signal at all, and will allow you to lower the gain of the sub amp, dropping the noise floor even more. Running it of a AC-DC converter will work fine, you will need to come up with a way to power the remote turn on though. This is usually done by the head unit in your car. In your case you could wire it to a switch, or you could wire a relay triggered by a remote control, so that the line driver turns on when you turn on the rest of the system.
     
  8. James Mudler

    James Mudler Stunt Coordinator

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    Ken,
    I now have time to go into more detail. The PLD-1 is a good piece. As Ken mentioned, I too was a an installer and the shop I worked for had test equipment galore. The TBA-T is not as clean. We measured many systems with o-scopes, rta's, linear X, and the PLD was a solid piece. The opamps in the TBA-T are not as high quailty and should be upgraded. The S/N ratio is a solid 108db. This info was told to be by the tech guru for PG at finals back in 97.
    I have a 15amp power supply out of a headunit/radio sound board. When the shop upgraded the display, the owner gave it to me. I power it up out of my line conditioner, and tie the remote and B+ together to turn it on along with a LCD monitor.
    I try to install it over the weekend. I have Sample Champion (purbits) testing software and try to post some before and after results.
    The only issue I forsee is impedance missmatch. Sorry for the spelling running late [​IMG]
     
  9. Kenny WH

    Kenny WH Stunt Coordinator

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    Thanks for all the replys guys,

    I already have a AC-DC converter running a 12volt type 6" lcd monitor in the theater for the 5800's osd so I don't have to turn on the projector when listening to music and want to adjust something. It's turned on by one of my line conditioners so I'm good to go on the power side of it.

    I did think of some things while mowing the lawn today;

    the PLD-1 if I remember right can put out up to 8 volt rms, how much voltage is too much?

    I guess start at the low end and just make small adjustment till the clip light barely flickers and then back off a bit?
     
  10. Kenny WH

    Kenny WH Stunt Coordinator

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    After installing the PLD-1 this morning here is what I've observed so far, please keep in mind I have not really played with it much but here's some preliminary findings;
    With the gain on the PLD-1 set to full and the S1000 on full I could not get the clip light on the S1000 or the peak light on the PLD-1 to flicker,even while listening to bassy music. But I was getting nervous cause the ceiling sounded like it was about to cave in from the vibration. Way too much bass, the subs way overpowered my RF-7's which are quite powerful and dynamic running off a QSC PLX 1602(300w a side a 8ohm stereo). I did not have this problem before[​IMG].
    You can definitely turn down the sub amp gains, I've turned my amp gain down from max gain to around two-thrids. Plus I turned down the sub level on the 5800 a couple db's and I still have as much or MORE clean bass than before.
    Even with the reduced gains, bass seems much more consistent and has improved dynamics in relation to my Klipsch main speakers at lower volume levels. I guess the voltage from the sub out on the 5800 is not very strong at lower volumes,especially for pro-sound style amps.
    Overall it seems that the S1000 can now really stretch it's
    legs, where before it seemed like it was starving for signal from the 5800. Now it seems like I am really hearing what over 1000 watts can do when running into the ULTRAS. It seems like my bass is much fuller at all volumes now than it was before.
    So far I detect no ill effects from adding the PLD-1, such as noise, etc. Like James said,"the PLD-1 is good piece".
    James, I look forward to hearing your experience with it as well. I hope you will be as happy with it as I am so far.
    Thanks,
    Ken
     
  11. James Mudler

    James Mudler Stunt Coordinator

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    Ken,
    Thanks for the update. Good to here you are happy with the PLD-1 in your HT setup. I did not get a chance to try it myself. The honey-do-list, was to long [​IMG]. I'll report my finds as well. Later
     

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