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Stewart World 1.2 Power Amp???

Discussion in 'Amps [BG]' started by jokerjkny, Mar 15, 2002.


  1. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    hey all,

    i've been interested in these for a while now, but am cautious, cause people have complained of the lack of thump(?). is this true?? 10 lbs. in a single rack space pushing 1200 watts is no joke, but what do you guys think? anyone using one?
     
  2. boogiebass

    boogiebass

    Joined:
    Aug 16, 2000
    I think I want one...
     
  3. Whappo Grande

    Whappo Grande

    Joined:
    Feb 9, 2002
    Location:
    Santa Clara, CA.
    Disclosures:
    Manager: AccuGroove Speakers
    I can only tell you about the 2.1 since it's what I use. You won't find a better built, reliable or sounding amp...period.

    Whappo
    http://www.accugroove.com
     
  4. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Joined:
    Mar 29, 2000
    Location:
    Sactomato, CA
    Hey Joker, I have the older model PA-1000, which is essentially the same amp as the world 1.2. I've had it for more than 5 years, and I've abused it using it for bass and PA, and it just keeps on going. I experience no lack of "thump" with this amp, and I really like the low end. It's uncompressed, and doesn't bottom out, even at high volume low frequency levels. It can get hot however, so If you plan to use it in the sun at maximum power, then I wold put a fan on it, but otherwise, it should be fine.

    I used it at 2 ohms a side for extended periods of time and had no problems.

    if you have any questions...
     
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  6. Cool to see folks yippin' about this amp. It seems too good to be true...? if this amp is so great why don't more folks use it? What about slew rate? That would dictate how "punchy" the amplifier would be, correct? I know that they need a steady supply of AC or they get "slushy". I guess most other amps store the AC is big transistors or caps or something? This amp gets around that by using what comes out of the wall, giving it a more "direct" line to your speaker cabs.....less AC, less "punch." This is what I've read..not what I've experianced. Is this amp the Holy Grail or what guys..??? You tell me.
     
  7. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    Subby brings up some points that i heard as well, and was wondering if y'all experienced the same.

    i didnt ask that at first cause i didnt want owners second guessing themselves. but it seems that the guys who are usin' em are happy. thing is i wanna get sometihng to replace my WT400 head. its ok, but i recently played thru an Aguilar DB659 that knocked me out, so i'd love to use it, but only need a poweramp for maybe 600 watts into 4 ohms for my 2 soon-to-be Berg 1x12's.

    coyote,

    have you seen or tried the newer 1.2? is it still one rack space?? if i got the aggie and stewart in a 2 space rack bag, ya think i'd be asking for trouble??

    that's another thing, some say that it doesnt quite fit alot of rack bags. i do extensive giggin' all over NYC, getting in and out of cabs, i dont wanna mess with a plastic box and want something i can sling on my shoulder. anyone know a good rack bag that would fit?
     
  8. Whappo Grande

    Whappo Grande

    Joined:
    Feb 9, 2002
    Location:
    Santa Clara, CA.
    Disclosures:
    Manager: AccuGroove Speakers
    “What about the slew rate?”
    It’s 30V.

    “If this amp is so great why don't more folks use it?”
    It’s a pro audio amp for PA’s, which is where you’d see more of them in use. They are not interested in setting up every Tom, Dick & Harry as a dealer. Therefore, you have to look to find something this good.

    “I know that they need a steady supply of AC or they get "slushy".”
    I’ve never experienced this nor has anyone I know. Any amp, regardless of type, that does not get enough consistent power will have problems & could end up with component failure over time. If you play in clubs where power is a problem, invest in a voltage regulator. This will keep the voltage consistent to your amp regardless of the AC outlet. (minus blackouts)

    Whappo
    http://www.accugroove.com
     
  9. So...a Holy Grail it is? 1200w, single space? What about the PV DPC 1000? That's a single space too...

    [​IMG]
     
  10. allan grossman

    allan grossman

    Joined:
    Sep 8, 2001
    Location:
    surreal city, usa
    Hey, Mad Subwoofer -

    I finally put 2 and 2 together.

    If you're looking for a light, high power single rack space amp Peavey still makes the DPC1400X.

    Although the Stewart's 30v/µs transient response is good (it's high enough to be inaudible), check this out:

    re slew rate from the DPC1000's owner's manual:

    "The amplifier output slew rate is internally controlled to optimize phase linearity and improve transient response. Due to the nature of the amplifier design and the internal signal conditioning circuitry it cannot slew rate limit."

    and from the DPC1400X manual:

    "The slew rate is internally controlled by a Bessel filter to optimize phase linearity and improve transient response. Because of this circuitry, the amplifier cannot slew rate limit."

    No slew rate at all? Sounds excellent - but I'd feel better if Peavey would give some number for transient response.

    Some other stuff - The DPC1000 is not 4 ohm stable when bridged, the Stewart and DPC1400X are. The DPC1000 is not 2 ohm stable but the Stewart and DPC1400X are.

    The Stewart and DPC1400X make rated power into a 2 ohm load, the DPC1000 is rated at a 4 ohm load. So - into a 4 or 8 ohm load both Peaveys are louder. Into a 2 ohm load the DPC1400X is louder than the Stewart, and as I mentioned earlier you can't run a DPC1000 into a 2 ohm load.

    The Peaveys are also noisier - my DPC1000 has a S/N ratio of >90db, the DPC1400X is 95db and the Stewart is >100db.

    THD at rated power is 0.2% for the DPC1000, 0.1% for the DPC1400X and < 0.1% for the Stewart.

    I don't know about fan noise on the Stewart but the DPC amp fans are controlled by load - they run (and make a little noise) all the time and run faster as thermal load increases - the fans speed up when you play through the amp - but even practicing in my living room the fans are only audible when I'm not playing. It's a little weird but the only time this would make any difference is in the studio, I guess. I imagine the Stewart uses a similar setup but I don't know that for sure.

    For my needs my used DPC1000 won - I got mine for $350. There's one on the Dudepit for $600 but I think if you tell the guy you know someone who just bought one for $350 he might sell it for less - he's been sitting on it for awhile.

    hth,

    allan
     
  11. I already sort of figured the 1400X to be the right choice...thanks for all that info, phew! The only question I really have about the DPC is the digital thing. Does the amp control the mosfets digitally or does it convert your signal into little 1's and 0's. I couldn't live with that.....other than that, the Peavey seems the best choice, no?
    :p
     
  12. allan grossman

    allan grossman

    Joined:
    Sep 8, 2001
    Location:
    surreal city, usa
    I don't know the answer to that, so I'm gonna guess :eek:

    A note on Peavey's modified Class D power amps (the DPC series):

    Instead of creating the audio signal by simple Pulse Width Modulation or duty cycle variation of a square wave, Phase Modulation uses two switches operating at the same frequency. By controlling the phase angle or time difference between the two waveforms and processing them differentially, the output varies from full off (0 phase shift) to full on (180°). This approach does not suffer from the difficult turn-on speed and symmetry problems that limit the performance of conventional PWMs. Vertical mosfets are the output device of choice due to their ability to turn on and off very quickly.

    Does the DPC series digitize the signal? I don't think so but can't say for sure. I use a tube preamp with a DPC1000 and it sounds like a tube amp but a heck of a lot louder.

    Maybe someone else can shed a little light on the subject.

    allan
     
  13. bben

    bben

    Joined:
    Feb 28, 2002
    Location:
    Santa Fe, NM
    A lot of the small-yet-powerful amps use Class D "digital" technology, which switches the output circuitry between on and off very rapidly. This includes the AI Clarus, Peavey DPC series, Stewart World series, QSC PLX series, Crown K series, and others.

    Each manufacturer has a slightly different way of doing it, with their own terminology and hype about why their way is the best. Until recently, Class D amps weren't very reliable, but that seems to have changed.

    There was a little bit of info on this in the BassTech column in the February Bass Player magazine, and you can learn all about it by poking around on the web.

    Traditional power supplies need a big heavy transformer, and vary the voltage in the output cicuitry instead of switching it on and off.

    You pay extra for less weight. For example, if I remember right from looking briefly at the schematics (they are online), the QSC PLX2402 and RMX1850HD have virtually identical output cicuitry. The PLX 2402 has more output, weighs 21 lbs, and costs about $800. The RMX has a few dB less output, weighs 45 lbs, and costs under $500.
     
  14. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    Wow, Grossy,

    this is some really nice stuff here. i'll definitely check out the peavey. but, since you did your homework, are there any other manufacturers who make power amps this small???

    also, do you find that's a bit too deep for some rackmounts?? i'm thinking of getting a rack bag, yet i know most dont quite fit the tight confines. what do you use?
     
  15. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
  16. Chuck M

    Chuck M

    Joined:
    May 2, 2000
    Location:
    San Antonio, Texas
    I've been using Stewart power amps for about 3 years now. They are the best sounding power amps that I've owned. I presently have a PA-1000 and a World 1.6.

    I had a World 1.2 but it had a recurring problem so Stewart replaced it with the 1.6 World for a $50 upgrade charge.

    I've tried the Peavy amps and they sound compressed to me. Some players like them and some players do not like the Stewart amps. Best to listen to them yourself before you buy.

    I played an outside gig last night. The power was pretty shaky and I neglected to bring a power conditioner/regulator. My PA-1000 never missed a lick and sounded wonderful. I have yet to have a problem with my Stewart amps being sensitive to a/c supply power. I do recommend using a power conditioner/regulator on gigs where a/c supply is suspect.

    Chuck
     
  17. allan grossman

    allan grossman

    Joined:
    Sep 8, 2001
    Location:
    surreal city, usa
    jokerjkny said...

    this is some really nice stuff here. i'll definitely check out the peavey. but, since you did your homework, are there any other manufacturers who make power amps this small???

    I think someone already answered this.

    also, do you find that's a bit too deep for some rackmounts?? i'm thinking of getting a rack bag, yet i know most dont quite fit the tight confines. what do you use?

    With banana plugs in the speaker outputs my DPC1000 clears the back of my rack with about an inch to spare - and the rack is 17" deep. I bought a 4 space Rollex rack and I think the whole rack weighs about 30 lb. With a power amp that light I don't see the advantage to a rack bag - but that's just me.

    allan
     
  18. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    Hey chuck,

    you might have had the "DDT - Distortion Detection Technique" engaged. in the bass player article i posted, T. Buddingh said it sounded a tad bit compressed with it, but disengaging it made things lubby.
     
  19. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    thx gross,

    nobody really said anything else about other 10 lbs., 1 space rack jobs, other than the peavey and stewart, but i guess that's it.

    30 lbs.?? wow, that is light. but i still would like a cool rack bag to sling on me, only cause i've got 4 flights in a pre-war building along with my two 1x12's, my bass, and an effects board... oi...
     
  20. Chuck M

    Chuck M

    Joined:
    May 2, 2000
    Location:
    San Antonio, Texas
    Joker,

    You may be correct but I don't remember seeing any switch for the compression. I also tried a CS-800 and it sounded compressed even at low volume.

    Chuck
     
  21. jokerjkny

    jokerjkny

    Joined:
    Jan 19, 2002
    Location:
    NY / NJ / PA
    hmm...

    well, its the "DDT" button on the front beneath the "bridge" button. but if you didnt like it at low volumes, then that gives me pause, cause i'd be using it in some situations for low acoustic work too.
     

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