Need help with SVP Pro

Discussion in 'Amps and Cabs [BG]' started by svp, Nov 11, 2013.

  1. svp


    Mar 12, 2007
    Recently purchased a svp pro pre, now I could use some help picking a power amp. It is my understanding that the output sensitivity rating is on the low side on these preamps and the input sensitivity rating needs to be low on the power amp also, if this is not true please tell me. So for I am leaning towards a QSC PLX 1602, but I just want to get my power amp selection right the first time, thanks in advance for the time and help(would love to hear from Bob Lee):D
  2. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Output of the preamp is voltage. On a power amp you have voltage sensitivity, and a lower number is more sensitive, if its high on the power amp, might be a problem, if its low the knobs sort it. Also with how cheap power is now, being able to drive amp to full swing is not really necessary.
  3. chadds


    Mar 18, 2000
    Wish your two points were true.
    There is also an impedance issue and I don't mean amp to cabinet. When you're not driving an amp to it's fullest the combination pre & amp can sound tepid and no amount of knob twirling will fix it.
  4. OP, your new SVP-Pro has plenty of output voltage, sufficient to drive any power amp.
    Note: this is the 1/4" output, not the DI.
    The DI is only suitable for driving a console.

    The weak SVP preamp is the SVP-CL, with a gain of only 23dB / 27.2x multiplier.

    SVP-Pro specs call for 76dB of total gain, or a multiplier of 37.6x
    This multiplier will boost a 150mV passive pickup to 5.64 volts.
    The stock PLX-1602 requires 1.2v input to reach full power.
  5. What do you mean? I'm pretty sure they would have designed the amp to be able to drive a 10k~ input on a power amp.

    output impedance doesn't change with drive in this ciruit
  6. chadds


    Mar 18, 2000
    Of all the pre amps out there that one is known to have a particularly low output. There has not been a standard in Bass preamps. An integrated head is proprietary and only has to work internally. PA power amps over the years have what appear to be three different voltage standards.

    Search. There has been a lot of conversation about this.

    Your pre and your amp may work great. No worries. Nope, impedance between the pre and amp. It has nothing to do with the output of the amp.
  7. chadds


    Mar 18, 2000
    There you go your answer appeared above!
    My error on which Pre you own!!
    Good playing!!
  8. svp


    Mar 12, 2007
    Thanks to the TB community for the responses to this point. Let me say I have never done the pre-amp power amp set up before, having said that from the research I have been able to do at this point I have narrowed my choices down to the following. Crest Audio CA6, QSC PLX 1602 or 2402 also the RMX 2450. If you folks would please give your opinions on which one would work the best for semi-loud hard rock bass paired with my Ampeg SVP Pro and why (if there is one I have not listed above that would killer please mention). Thanks so much for the help:confused:
  9. Consider the weight of the amp.
    The CA6 and RMX are both lead-sleds.
    PLX is 21 pounds.

    Also consider a Crest ProLite 2.0, which is 11.8 pounds.
    I bought one of these because of the 10.375" depth, light weight, and built-in 100 Hz 4th crossover for biamping subs.

    If you have not been done the power amp road before, I can tell you with certainty those heavy amps get real ugly at closing time.
  10. svp


    Mar 12, 2007
    What about handling the strong bottom end of a bass, I have heard the CA6 does very well with that:confused:
  11. All decent power amps handle the bass end.

    CA6 is a very nice amp, all 44 pounds of it.
    The ProLite are not as sturdy built, nor do they weigh as much as CA6 or PLX.
    The PLX at 21 pounds is very well built and big heat sinks. ProLite has these

    Road Ready, and other true ATA cases I have not seen in 3 rack space sizes.
    CA6 + SVP-Pro (53 pounds) + 25 pounds for RoadReady 4RU rack = 88 pounds total. Been there, done that.
    I don't think an SKB plastic rack will tolerate that much weight.

    I keep each PLX in a 4RU RoadReady case. 21 + 25 = 46 pounds.
    The rear of the amp is secured to the rear rack rails.
    Most of these have a 1RU Rane crossover, and the 4th slot is empty with a blockoff plate.
    My preamp pair (RPB + VTRM) are in a separate 2RU ATA case.
    Two racks, but less weight than a single rack.

    I encourage you to think long and hard before buying a lead sled.
    They are great amps (owned several), but the weight is too much.