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Thread: Some amp questions from a retard

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    Some amp questions from a retard

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    I have been using the crappy powered mixer that this local bar provides up until now. But I am looking into buying a minimal but non-crappy PA system. Most places I will be playing will not have more than 100 people or so (indoors). When looking at amps, I see that they rate the wattage per channel at different ohmages. What does this really mean? Should you set them at 2 ohms, 4 0hms, 8 ohms, bridged? I am quite sure this is a dumb question, but it will help me figure out which amp to buy. Even a link to a website with such info would be great. Thanks.

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    Quote Originally Posted by pdadda
    I have been using the crappy powered mixer that this local bar provides up until now. But I am looking into buying a minimal but non-crappy PA system. Most places I will be playing will not have more than 100 people or so (indoors). When looking at amps, I see that they rate the wattage per channel at different ohmages. What does this really mean? Should you set them at 2 ohms, 4 0hms, 8 ohms, bridged? I am quite sure this is a dumb question, but it will help me figure out which amp to buy. Even a link to a website with such info would be great. Thanks.
    Not a Dumb Question
    The ohmage is determined by the type and number of speaker cabs being used. Cabs come different ohms; 16,8,4 and, rarely, 2 ohms. If your amp say it can run 200 watts at 8 ohms, then you can run two 16 ohm cabs or one 8 ohm to get the 200 watts. If it says 200 watts at 2 ohms, then you can run one 2 ohms, two 4 ohms, four 8 ohms or 8 16 ohms. And on some tube amps you also have to select which ohmage you're going to run, though I've never run into one. If the amp is stereo, this applies to each side. Also, you can bridge most Stereo power amps, giving you a mono signal, but a increase in power. Most bass players do this, but I don't think it usefully for PA. And I also don't run my amps at 2 ohms; I like a little safety margin. Did all of that make any sense?

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    this makes alot of sense, thanks !
    now, why don't live PA engineers use the bridged mono mode ?
    since most live PA mixes are kinda Mono.....then whats wrong with using the bridged mode ?
    what do you loose? a tiny little bit of stereo image that probably won't even benoticed by the crowd ?
    or is there more...

    and now that we are talking about AMPS for small FOH systems,
    can you name a few brands that do a fine job?
    i see that there are Many amps on the market that produce lots of watts,
    but i just don't know much about "Live gear",
    brands i should check out,,,brands i should stay away from...
    popular modals for clubs or venues that can host a maximum of 300 people...

    ...edit....
    additional question:

    so if i get it right, then the Higher the Ohm on your speakers, "the better",
    and the lower the OHM on your amp, the better,
    since this gives you alot more connection possibilities ?
    ...so you only gotto make sure your Speakers have a higher Ohm-age than the amp.......
    Real curious !
    cheers,
    earworm
    ...listen...

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    If you are using more than one speaker, bridged mono doesn't do you any good. (send the same signal to both sides of a power amp and hook one speaker to each side) If you only have one speaker that will handle the power, bridged mono will do what it is supposed to.
    Jay Walsh
    Farview Recording. I am also the forum spokesmodel for Terasyne Amplification

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    interesting,,,i'm learning,
    and next month i'm gonna start hunting for some amps to do small live gigs,
    so any recommendations for Brands...
    whats junk,,,what's nice// cause for LIVE i don't really know where to start looking...

    thanx
    ...listen...

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    All the speakers I have looked at are 8ohms. What are some 4ohm speakers?

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    Quote Originally Posted by earworm
    this makes alot of sense, thanks !


    and now that we are talking about AMPS for small FOH systems,
    can you name a few brands that do a fine job?
    i see that there are Many amps on the market that produce lots of watts,
    but i just don't know much about "Live gear",
    brands i should check out,,,brands i should stay away from...
    popular modals for clubs or venues that can host a maximum of 300 people...
    Yamaha, Soundcarft, Mackie and some Behringer, if you have to watch the bills.
    ...edit....
    additional question:

    so if i get it right, then the Higher the Ohm on your speakers, "the better",
    and the lower the OHM on your amp, the better,
    since this gives you alot more connection possibilities ?
    ...so you only gotto make sure your Speakers have a higher Ohm-age than the amp.......
    Real curious !
    cheers,
    earworm
    Ok, the other side of the coin is this; 16 ohm speaker aren't as loud as 8 ohms, 8 ohm aren't as loud 4 ohm, 4 ohms aren't loud as 2 ohm. I'd said 8 ohm cab are sorta standard for small PA systems. Now there is some other complicated stuff regarding SP and surface area and other esoteric s**t. But, I'm not the one to speak on that. This is just practical experience. And most amps will adjust to whatever ohmage speaker load you're running. But, if you drop the load too low, you're risking burning the head, I mean FIRE!!! Flames, smoke, the whole lot.
    Here's a few small package's at Musician's Friend; Sweetwater, Zzounds and others have similar packages.
    http://www.musiciansfriend.com/srs7/...se_pid/631362/
    http://www.musiciansfriend.com/srs7/...se_pid/630119/
    http://www.musiciansfriend.com/srs7/...se_pid/605257/

    And, you get what you pay for.



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    OK, I have about $1000 to start building my PA. I was thinking of:
    Yamaha MG 16/4 mixer
    JBL JRX 115
    JBL JRX 112M
    Crown XLS 402 or QSC rmx 850
    That would run me just a bit over budget. What do you think? This is mostly for indoor stuff, no more than 100-150 people. If I only have the money for one speaker and one monitor or two speakers, which would you recommend? I figured I would use one as a monitor until we can buy more stuff in a few months.

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    Definitely, two speakers. You need to get the wide spread.
    Get 2 of the JBL JRX 115s
    that'll get you started.
    Last edited by lbanks; 12-01-2004 at 12:32.

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    You think the JBL's are any better than the Yamaha Club speakers? I had looked at the Peavey PV-215's for the double 15'' speakers. Plus they're cheap. How do those sound? I hope to go listen to all these in a week or so, and I'll post my opinions.

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