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Which pro amp to go with??

Discussion in 'Amps and Cabs [BG]' started by Thumpinthenight, Apr 13, 2004.


  1. Thumpinthenight

    Thumpinthenight

    Apr 13, 2004
    New York
    I am about to purchase a power amp to go with my Ampeg SVP-PRO pre-amp. I'm thinking Carvin DCM1000, DCM1500, QSC RMX1450, or QSCPLX1202. I have 1 Hartke 4x10XL (400watts), and a Hartke 115XL (200watts). I currently use a Hartke 3500, and plan to use this for a practice/backup amp. I'm not sure how much watts is ok to put thru these cabs via these powerful amps. Is it ok or better to use a more powerfull (say CarvinDCM1500) than say the DCM1000? Also, which is better-running in stereo with one cab/channel? or getting a lesser powered amp and run bridged?
    Is there something special about the QSCPLX seies other than weight reduction that makes it worth the $?
    Doing small to medium indoor gigs and an occasional outdoopr lawn picnic, I'm thinking the Carvin DCM1000 might suffice. Any thoughts or experience would be appreciated. :help:
     
  2. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    Your power amp has a huge effect on your tone. I would buy the best power amp that you can afford. The PLX amps are highly regarded here at TB. They sound excellent and the weight feature is a bonus. I have never had an ounce of trouble with any of mine, I have three (2ea 1602's and 1ea 2402). I would at a minimum buy a 1602. If you can afford it, buy the 2402. Good luck!
     
  3. Schwinn

    Schwinn

    Dec 4, 2002
    Sarasota, FL
    Hi there, are you the one from the ampeg forum? You'll like it better over here :)

    To answer your question about the amps you listed, I think most would agree that they will all be the same (i.e., not enough power difference to make a difference in volume). PLX is preferable because its half the weight, but they will all sound as good. About which mode to run in, you can try running in stereo or parallel, but if you clip the amp too easily, switch over to bridged. I can tell you from experience that the QSC amps run in bridged mode very well. They get warm, but hardly break a sweat :D .
     
  4. Thumpinthenight

    Thumpinthenight

    Apr 13, 2004
    New York
    Hey Schwinn. Yepper, that's me movin' over from Ampeg 101 board. Thanx again for the input. With about $4bills in my pocket, I think I'm leaning to Carvin DCM1500. Stereo is my plan, but that would mean 300 watts going to my 200watt-115XL, and 300 watts to my (400watt) 410XL-if my calculations are correct. Each cab is 8ohm. I hope that's ok. As far as "clipping" what would cause that? :meh: Green again.
     
  5. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    Thump,

    If you are smart and know how to operate your rig resonably (volume), I would recommend to try and bridge. Bridging is going to give you the "clean headroom" effect. This is what, I feel, is most responsable in cleaning up your tone when switching from hybrid amps to a pre/power set-up. In fact, if you ran in stereo you would be more likely to clip your power amp than if you ran bridged. Power amp clipping is when you have pushed your power amp to the point where it cant push any more. You can also clip your power amp with to hot of input signal. Speaker clipping is when you throw to much power at your speakers. I run a PLX1602 bridged with 2 GS112's. These are rated at 350 watts a piece. I have yet to blow a speaker. You will find that when you under power your speakers you are more likely to clip your power amp. Why, because you need more volume and run the system to its limits. Power amp clipping is the worst kind if clipping. It can do the most damge and sometimes you dont even know it is happening. You can find used PLX1602's for $400-500 an regular basis. You have to know where to look. I would serioulsy hold up on the Carvin and go QSC :p Your ears and back will thank you for it later ;)
     
  6. GooseYArd

    GooseYArd Guest

    May 15, 2003
    That's not true. In dozens of well documented double blind listening tests, subjects have never been able to discriminate between individual transistor power amps with accuracy better than random chance, as long as they were withheld from clipping. Choose for power, price, features, reliability, but don't waste any time doing listening tests because if the amp is working correctly you'll just be imagining things if you hear any difference.
     
  7. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX

    In my real world experience I would have to disagree. I had a Crest CPX900. Aside from the power difference of the PLX1602. This thing had a huge effect on my tone. It sounded muffled and boomy. There were no highs or mids to speak of. I junked that and bought a PLX1602. What a difference! It sounded like someone took a blanket of my sound. Im sorry but, I dont care what test might say. I firmly beleive that poweramps do affect your sound. Maybe Bob Lee might be able to shed some light on this subject?
     
  8. Thumpinthenight

    Thumpinthenight

    Apr 13, 2004
    New York
    I'm getting it now, IOW don't pay too much attention to the speaker's wattage (at Ohms rating), it doesn't have to be under the amp's output wattage. Just run your amp at a lower gain setting-I guess. But I thought you run the amps gain setting on almost full for max clean power, and keep the volume output on the pre-amp down low? :meh: If you run 2- (8 ohm) cabs in bridge mode, that's the bridge 4 ohm power rating-pretty high. How can you run 2-(4ohm) cabs in bridge mode-that would be a 2 ohm load-which I haven't seen on any amp ratings yet? I guess you can't. :eek:
     
  9. g4string

    g4string Supporting Member

    Sep 19, 2002
    Melissa, TX
    I think the PLX can be bridged with 2ea 4 ohms cabs, however you might want ask them first. Bob Lee is a member of TB and a QSC employee. He is extremely knowledgeble and could answer your question about the 2 ohm load. You are correct about running the amp at 90-100% all the up and then making all gain adjustments at the preamp. Most bass players and sound techs run their amps this way.

    Think of your power amp like the voltage in your house. Imagine (if you dont) have a dimmer switch controling a light socket. The dimmer switch is receiving all 115V from your homes main electrical buse. But the switch will only allow the voltage that you demand by turning up or down the dimmer to pass through the rheostat and on to the light bulb. A pre/power rig is the same way.

    The thing that is going to most demading on your amp while bridging is heat, espeacily at a 2 ohm load. The reason being is that you have all this power from the power amp ready to go, but it is being held back until there is demand for it (although hard on amps, it is good to have as a bass player, especially important with transient peaks and valleys). It is kind of like running your cars engine as fast as it go (in nuetral of course) with the brake set. The main you thing you need to be concerned with when bridging is keeping the amp cool. Same thing applies with your cars engine!
     
  10. check out the ampeg power amp, that 'll work good with the ampeg pre-amp
     
  11. bill7122

    bill7122

    Feb 23, 2003
    Albany NY area
    I have a Crown CE1000 that I'm planning to use to build my rig. Opinions???? :meh:
     
  12. GooseYArd

    GooseYArd Guest

    May 15, 2003
    As long as you "believe" the idea, which is kind of a metaphysical thing, the power of suggestibility will make it so, and you'll hear differences. In all likelihood the other amp was simply louder, and in almost every blind listening test simply increasing the volume by way of power sounded "better" to subjects.

    Double blind listening tests are substantially more a real-world experience than an informal, not even AB listen by single person. In an ABX test you take scores of people, possibly even hundreds, and ask them to do real, critical listening in a controlled environment, where they can't see which amp is connected and be affected by excitement. It is particularly important in the case of people who already strongly believe that theres going to be a difference to be figuratively blinded from knowing which signal they are hearing because ego will unconsciously be a motivator. It sucks but its true.

    It is of course possible that your old amplifier was malfunctioning in such a way as to impart a muffled and boomy quality to your sound, however, it wouldn't be logical to make the leap to assuming that all power amps sound inherently different.
     
  13. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I agree with GooseYArd. The ideal amplifier is, metaphorically, a straight wire with gain. The closer amplifiers are to the ideal, the more alike they should and will sound.

    To properly compare two amplifiers, their gains have to be matched as precisely as possible (ideally, the listening should also be done blind, but that's difficult for most people to set up). Even two identical amps of the same model will sound different if their gains are different. Because the human auditory system's sensitivity to various frequencies--especially lows and extreme highs--varies greatly with SPL, the louder amp will invariably sound punchier, tighter, thumpier, et al.

    If two power amps, with their gains matched and in identical systems, and operated within their linear range, sound different, there is probably something wrong with at least one of them. I would expect solid state amps from manufacturers that are established/reputable/respected/know-what-they're-doing/whatever (and I would place Crest in this category, as well as QSC, Crown, LAB Gruppen, and a number of other brands) to sound very much alike, maybe even indistinguishable from one another. There may be audible differences in the way they handle extreme situations like clipping, abnormally low load impedances, high EMI and RFI, and such.
     
  14. GooseYArd

    GooseYArd Guest

    May 15, 2003
    This is why I only use QSC amplifiers :)
     
  15. Schwinn

    Schwinn

    Dec 4, 2002
    Sarasota, FL
    Thump,

    You will be safe running in bridged mode with any cabinet (or 2 8ohm cabs chained together). Don't worry about the speaker rating being lower than the amp output. When you buy a cable for your new setup, just remember to get a speakon cable that has a NL4FC Neutrik connector. http://www.neutrik.com/start.asp Sounds complicated but it isn't really. This particular connector is 4 pole, and it must be wired to +1 and +2 terminals, which doesn't require soldering, just a screwdriver.

    I usually run my power amp at full (gain 1 all the way up) and adjust volume from the SVP. Good luck.

    Refer to this thread as well:
    http://www.talkbass.com/forum/showthread.php?t=80647&highlight=pole+speakon
     
  16. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Yes, with a solid state amp you can run it with no load attached. If you have two channels, can use one for whatever and the other for whatever else, including nothing.
     
  17. Thumpinthenight

    Thumpinthenight

    Apr 13, 2004
    New York
    Schwinn, thanx, and I hear you about the neutrik connectors, but both my cabs have only the std 1/4 inch connection. I've talked to some local shops, and they said they make neutrik on one end and 1/4 banana plug on the other. Is this ok? I know it's probably not the preferred.
     
  18. Schwinn

    Schwinn

    Dec 4, 2002
    Sarasota, FL
    Yeah, its ok. The cable I use is speakon at one end (into amp) and 1/4" at the other (into cab).

    You're right, it's not prefered because any benefit in power handling you get from the speakon is lost at the 1/4" connection. You know how the saying goes, a chain is only as long as its weakest link... One day I will install speakon connectors on my avatar cabs, but that is more work than I can deal with right now :(
     
  19. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    The cool thing about cables is that one type of connector can go on one end and another type can go on the opposite end. Just like the detachable power cord on you computer and other gear; one end is an IEC connector, and the other is the plug that is approriate for your AC outlets.

    Having a Speakon on one end of a cable and a 1/4" on the other is what you need, so that's what you should get. It'll work, but keep in mind that a 1/4" connection is not as robust or reliable for speaker power levels. You probably don't need to right away, but you could consider upgrading to a Speakon connection on the cabinet some time in the future.