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Amplifier recommendations anyone?

Discussion in 'Sound, Music, and Intercom' started by quarterfront, May 19, 2009.

  1. quarterfront

    quarterfront Member

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    I'm shopping for an amplifier and figure it can't hurt to ask here if anybody has an amp that the really love which fits the profile for what I'm doing. Here's the situation:

    400 seat theatre, does comedies, musical reviews, mysteries, etc....

    The rest of the system:
    Mains are Meyer CQ-2's.
    Delay ring is EAW JF60's powered by Crown K1's.
    Subs are powered by an old Carver amp.

    The amp I'm replacing:
    A Carver amp (c.1987) that drives sound for the "Suite", a small balcony. Sound for the Suite comes from 1) a pair of EAW JF60's, and 2) a delay system of JBL Control-1 mini speakers.

    So: I need a 2 channel amp and I need to drive less than 200w into 2 ohms.

    I'm looking at a Crown XLS 202D. It can deliver more watts than I need, but that just means I'll be running it cool, the price is right, and I've always figured you can't go too far wrong with Crown amps.

    OTOH, I'm a lighting guy first and a sound guy second (or third) so...

    Any recommendations?
     
  2. rwhealey

    rwhealey Active Member

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    The XLS202 does not appear to be rated for 2 ohm operation.

    Try the QSC RMX850. It's heavy, but a tank.
     
  3. waynehoskins

    waynehoskins Active Member

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    If your speaker cables in question are home runs, you could split the load onto multiple lighter-weight amplifier channels. Perhaps as light and easy-to-find as Crown D75s, or as newfangled as Crown CTs4200s. Or a couple of XLS202s. Something like that is what I'd look at if it were me.
     
  4. quarterfront

    quarterfront Member

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    On the data sheet it gives specs for power consumption under a 2 ohm load, so I figure it's built to handle it. I'll look at the QSC, though. Big part of what I'm after is quiet - this lives in the booth with the SM, so a variable speed fan would be nice. The K1's run totally silent and it's great....
     
  5. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Not on my data sheet. :rolleyes:

    Someone mentioned if there was home runs to split it into multiple channels... Now I don't think that's needed. I think that if you can reconfigure the load to series parallel or some other configuration then you will get away from your impedance issues...
     
  6. museav

    museav CBMod CB Mods Departed Member

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    I think any discussion of load or power requirements is pure conjecture without knowing specifics such as the quantity of speakers and how they are wired.

    Here's my thinking, it sounds like you need one channel for a pair of EAW JF60s. The original JF60 was rated for 200W and 5 Ohms, the current JF60z is rated at 200W and 8 Ohms, so whether it is a 'z' version or not can be a significant difference. You apparently need the second channel for some unknown number of JBL Control 1s. There have been numerous versions of the JBL Control 1, the current Control 1 Pro is rated for 150W and 4 Ohms, most previous versions of the Control 1 had the same ratings but there were some versions that differed, such as the Control 1AT that had an internal transformer for 70/100V operation and which might be used for a delay fill application. So we don't know how many Control 1s you have, we are not sure of which version of the speakers you have and we don't know how they are wired. However, based on the speaker product information I don't see anything that seems to directly relate to a an amp rated less than 200W into 2 Ohms. I'm not saying that it is wrong or is not a good option, but how did you establish that you need an amp with two channels rated 200W or less into 2 Ohms?
     
  7. quarterfront

    quarterfront Member

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    Brad -

    How I got to the conclusion I got to is that 1) the old amp is a Carver PM-350 and it's worked fine for years, 2) the EAW's are the 5 ohm version and I'm running them in parellel with only one home run, 3) the EAW's will only take 200w max, 4) there are 6 JBL's that are fed via some sort of transformer system that I've never bothered to suss out but which has always worked and which has always (since 1987) been fed by one channel of a Carver PM-350, and 5) even though odds are I'll never push this amp over about 50 watts it's always nice to have a bit more amp around for this particluar application because if something ELSE more important decides to let it's smoke out I can blow off sound to the suite that this amp powers for a few days and patch the more important speakers into this guy, but 6) I don't need to replace all 350 of those Carver watts, 'cause there's noplace around here where I need that much power.

    BTW, the JF60's were new 5 years ago, so this amp has been driving that load 7 days a week for 5 years. The amp has been driving Control 1's since 1987. 5 years ago the old Control 1's were replaced with identical new Control 1's when it bacame apparent that after 17 years the foam had gone to dust. Datasheet on my Control 1's says 8 ohms and a recommended power range of 10-80 watts RMS.

    Chris15, re the datasheet, here's what I'm looking at:
    http://www.fullcompass.com/common/files/3519-XLS-202_Power_and_Thermal_Data.pdf
     
    Last edited: May 20, 2009
  8. Chris15

    Chris15 CBMod CB Mods Premium Member

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    That data sheet seems to be outdated, refer to this one on Crown's website.

    The transformer system you speak of would most likely be a 100v or 70v line system, with said transformer doing the step up from a low Z load to high Z...
     
  9. museav

    museav CBMod CB Mods Departed Member

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    The Carver PM-350 is rated for 350W/channel into 8 Ohms and 450W/channel into 2 or 4 Ohms.

    The JF60 are rated for 200W each but you have two of them, so that's 400W for both of them. So 400W into 2.5 Ohms would not be out of line.

    The transformer does indeed indicate the possibility of a constant voltage system, probably 70V. I don't know how the transformer was wired to the amp, but a 4 Ohm primary connection wouldn't be unusual. Meanwhile, the JBL Control 1AT that would have been used in a 70V system had 7.5W, 15W, 30W and 60W taps, so six of those could be 360W. Add in a bit for line loss and 400W at 4 Ohms for that channel is a possibility as well.

    So without knowing anything more about the transformer or how the JBL's are tapped, it seems quite possible that the Carver P-350 was initially selected specifically because of its ability to provide 400W+ into 2 and 4 Ohms. Without knowing more it would not really be safe to assume anything less.

    FWIW, the only Control 1s that I can find that are rated 8 Ohms and 10-80 Watts are the consumer products, all of the pro or commercial JBL Control 1s, from the discontinued Control 1C, Control 1AW, Control 1 Plus to the current Control 1 Pro, are rated at 4 Ohms and 150W. Given that you have six of these speakers and there is apparently a transformer at the amp, I think you really need to verify exactly what you have, or what you originally had, and how they are wired before making any assumptions on what you need to drive them.
     
    Last edited: May 24, 2009
  10. David Ashton

    David Ashton Active Member

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    It would be good value to put an impedance meter across the line and see what it reads, this would remove a lot of doubt.
     

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