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Power amp with low input sensitivity? (~.7v)

Discussion in 'Amps and Cabs [BG]' started by dharma, Apr 6, 2006.


  1. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    I've as of yet been unable to find a power amp that is rated below around 1v, and my preamp choice is a .7v output level.

    To add to the criteria, I want it to be fairly cheap (under say $400) and fairly lightweight (~30 lbs at most, if possible) but I know that all of this is going to be hard to swing and am willing to wiggle a little. One up side is fairly low power output is no problem, I am working at 8 ohms as of right now, and bridgeable to around 400 or 500 watts at that rating is just fine with me. Anything more would be overkill for my needs at the moment.

    Any suggestions are welcome, and I've noticed that the Berg IP series internal power amp has that sensitivity, but $1900 is a little out of my range now.
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Most consumer amps will take a .775 (0dBu) signal. That, and having unbalanced inputs, is often all that separates them from pro-sound amps.
     
  3. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    Forgive my ignorance as I'm new to the power amp idea, but what's the difference between consumer and pro sound?

    I.E. name me some names?
     
  4. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    Nobody has any input? This is a first.
     
  5. Fretless5verfan

    Fretless5verfan

    Jan 17, 2002
    NorCal
    It's because you have a character from Big O as your avatar...:p

    In all seriousness though, what type of pre-amp is it? Some can have a minor adjustment made to boost thier output to match normal amps.
     
  6. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    Avatar - just an icon I found that sorta resembles me (I know, sad.)

    Preamp - SWR IOD, .7v output.
     
  7. zombywoof5050

    zombywoof5050

    Dec 20, 2001
    My Carver PM1400 has switchable input sensitivity (0.775v or 1.5v), but you have to open it up and add/remove (soldered in) jumpers on the board inside. It also has both balanced and unbalanced inputs. But it only goes down to 4 ohms per channel, so it can't bridge into less than 8 ohms (no problem for me, but some people like to bridge into 4 ohms). It's also heavier and pricier than what you listed.
     
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Consumer gear runs at -10dB, uses unbalanced connections. Pro gear runs at +4dB, uses balanced connections.
     
  9. BruceWane

    BruceWane

    Oct 31, 2002
    Houston, TX
    Crest CA and CD series amps all have .775v input sensitivity. CA's are heavier, but very well regarded. I don't know much about the CD series.

    Keep in mind that most power amps can have the input sensitivity modified to accomodate your needs. It's a pretty common thing. So if you've already got a power amp that isn't working well with your IOD, you could probably have it modded by a local tech.

    And a lot of times when you buy a new power amp the selling dealer will mod it for free, or a very small charge.
     
  10. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    That's a pitiful preamp output.
     
  11. Yes indeed. The IOD DI output is 0.7v maximum output, balanced. Tain't consumer, tain't prosound. Go figure.

    I use a greater than unity gain device in the signal chain between the IOD and the power amp. This is a Rane EQ box, Rane MX22 active crossover, or DBX 120a sub-synth. All of these devices can boost the IOD signal to the 1.7v required by my PLX.
     
  12. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Yeah, you can practically arc weld with the output of my Rane DC 24 units. Every pre I've had can fully drive amps with 1.2+ volts sensitivity without turning up either their master gains or the amps' input all the way. Actually they'd all drive my QSC 3402 which requires the most of all the PLX series.
     
  13. 4runner

    4runner WARNING!"WALL OF DOOM" does "exceed" 140 decibels!

    Feb 11, 2006
    Hackensack NJ,
    Hey Dharma,
    I believe,"Crest", "Crown", and "QSC", are all designed to be driven to full output, with a 0.775 dbv input signal, and are equipt with "input sensitvity" swiches, to accommodate a variety of mixer / pre-amp, line level outputs. My Crown amp has three settings; 0.775v, 1.4v, and 26 decibel gain; which requires a 3.3v signal. There are alot of guys that are members of TalkBass, who have far superior Knowledge concerning the subject. :bassist:
     
  14. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    There are fewer amps that have user-accessible sensitivity settings - other than the knobs - that's what they are there for - than ones that supply extra switches.

    And really, why are some manufacturers building preamps that can't generate what the expected range is, what others can, what an average [channel of a] mixing board can? Is it because they can't supply decent gain and still end up with a s/n spec that passes muster? Preamps after all are supposed to be able to get the signal up to line level. That was originally their main purpose.
     
  15. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    So here's a question for you out in the open, bgavin: Does the Rane EQ you use produce enough boost just by virtue of you connecting it between the IOD and your PLX?

    I e-mailed Lord Valve about this very line of questioning and I believe he cribbed a little, telling me he used to do mods to overcome this, but now my best bet is to contact SWR about modifying the IOD itself.

    I think I may have gotten myself into the weeds on this one, my severe G.A.S. for the damn thing led me to grab one tonight. It's got real frickin' power tubes.

    Now for an amp. :meh:

    Also, after some looking, I'm curious about the 1u lightweight Stewart line. Is their 1v input rating accurate?
     
  16. The Rane ME30B will provide more than enough gain for your IOD to completely clip any power amp.

    The added benefit is you can use it to dial your rig to Flat, then use the IOD tone controls from there.
     
  17. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Since you didn't ask ; } - the Rane DC 24 is a great addition to a bass rig, just before the power amp. It'll drive anything to max and has two-band compression, crossover or summed crossover with band-balancing, downward noise expanders, limiting, and scads of clean headroom.
     
  18. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    Scads?!

    That's a lot.

    I mean, gobs or loads are expected, but scads would be a big improvement.
     
  19. Juniorkimbrough

    Juniorkimbrough

    Mar 22, 2005
    Mississippi / Memphis, TN
    Endorsing Artist: Lakland Basses
    a preamp with power tubes?:confused:
     
  20. dharma

    dharma Srubby wubbly

    Oct 14, 2005
    Monroe, Louisiana
    2 EL84's.
     

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