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  1. #1

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    Default SDA and power amps?

    I keep hearing that you need 200watts to wake up those sda's. I am biamping my 1.2tl's with two aragon 2004's. They are rated @ 100watts into 8 ohms. What would moving to a 200 watt amplifier do? I'm not going to listen to any louder. Thanks, soupbone

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    I always say, you cannot have enough power!

    I bi-amp my TL's with a Carver PM-1.5T on the drivers and a Carver PM-1200 on the tweeters. Both are rated well over 200 watts into a nominal 8 ohm impedence and I believe the TL's are around 6 ohms nominal.

    Doing the upgrade would cause you no harm and ensure the Polk's are getting even cleaner power with some reserve and lessen the chance of you clipping the amp and square waving the speakers. Square waving spells death to coil movements, so the cleaner with more reserve, the better off you will be.

    Joe:p
    An Unused Weapon Is A Useless Weapon!!

  3. #3

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    I have been thinking about upgrading my amps. They are as old as my sda's. I was thinking about 3 amps, the aragon 8008,anthem amp 2 and the sunfire amp. What do ya think?

  4. #4

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    I think 375 to 1000 per channel is not unreasonable. I listen only at moderate levels and can tell the difference between my Soundcraftsmen 250 per channel and my Soundcraftsmen 375 per channel. I have one of the Sunfire 300's as well but still favor the Soundcraftsmen 375. As you go beyond about 500W you really can't tell the difference at moderate volume. It seems the more power you have the cleaner and quieter the sound is. I seem to use a lot more power out of the soundcraftsmen than the Sunfire for the same in room volume. The Sunfire seems really loud at lower output levels??? I'm sure there is more at work here than just the measured output power.
    madmax

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    Default Loudness Compensation

    madmax,

    I'm wondering if the Sunfire has some type of loudness filter built in so that the lower midrange and bass frequencies are boosted as the volume is lowered.

    One way to tell is if you have a graphic equalizer with a calibrated microphone and white noise generator. If you start getting response peaks in the lower midrange-bass as you turn the volume down, well........
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
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  6. #6

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    Default Bi-Amping

    soupbone,

    Most of the 100 watts going to the tweeters is being dissapated as heat by the resistors in the high frequency portion of the crossover network. The mid-woofers are the ones that need the power.

    Try connecting the upper and lower binding posts together with high quality heavy guage speaker wire (like 12 guage) and using a single 200 per channel amp.

    As others axeman and madmax have said, it's not about being able to play louder, its about being able to generate a cleaner signal with less strain on the amp.
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
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  7. #7
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    Soupbone,

    Your 1.2TL's are still asleep - near coma like state. Zzzzzz.
    You are going to need at least 200wpc to wake them up.
    Now, to get them singing... I'd recommend two identical bridged amps capable of at least a 500w reserve. Your 1.2TL's are rated for 1KW. You should at least provide 50% of their rated power.
    Therefore, a minimum would be 500W - IMO.

    I have the 3.1TL's which are Polk rated at 500W. I pump 250 watts into them and they swallow it all up without so much of a hickup. If I had the 1.2's, I'd get a 2nd 250W amp, bridge them, and I'd send the full 1000W to the 1.2's.

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    One interesting note for rskarvan:
    I would have posted something similar to what you did but because of one experience I didn't.
    The Story:
    I had my 1.2's running on a 375w SC like I said above. I just got a set of SDA-CRS+ and a 250w SC that I was going to use in another room. Like any experimenter I hooked up the CRS setup next to the 1.2 setup and listened to both. I noticed the CRS were not awake and sounded like they were on the verge of distortion, not like the 1.2's. I then hooked the 375w up to the CRS's as a test and noticed they ate up quite a bit more wattage, really woke up and sounded great. Bad amp? (the 250w) I wondered. So I hooked the 250w to the 1.2's. They were awake and going strong. Not as far as with the 375 but still there. I think it is because they have more drivers and given the same amount of input power they deliver more volume.
    You are still right though. They deserve at least 500w per channel to be at their best and do what they are advertised to do.
    madmax

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    Default Soupbone/Good Post

    This is a question that has come up a few times over the years and you got darn good reponses here already.
    Power, and more POWER! SDA's do like it!

    I run my 2.3's with two - 750wattsRMS @ 8ohms bridged amps. They respond quite well to it. My 2B's are only getting 200wattsRMS pc@ 8ohms as HT rear surrounds and my CRS+'s aren't getting their 250wattsRMS pc@ 8ohms, and they don't like it.

    rskarvan/max,

    As to why some amps produce more with less on some SDAs....

    I have more lists for the sens. of the SDA line over the years some place but here are two years

    1988: 1 watt @ 1 meter sens.

    SDA-SRS 95dB
    SDA-SRS2 93dB
    SDA-1C 95dB
    SDA-2B 92dB
    SDA-CRS+ 92dB

    1990: 1 watt @ 1 meter sens.

    SDA-SRS 1.2tl 91dB
    SDA-SRS 2.3tl 90dB
    SDA-SRS 3.1tl 90dB

    If I remember correctly, an increase of 3dB aprox doubles the volume level, so when you look at the figures and do the math......

    It really depends on which model and what year your SDA is as to how loud it will sound with a paticular amp.

    (My 1989 SDA-SRS 2.3 89.7dB probably rounded off to 90dB by Polk)

  10. #10
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    Question:

    I have the 3.1TL's running off a single 250wpc amp.
    They sound fine.
    My amp is fed a signal from my Denon3801.
    I wonder if bi-amping the 3.1TL's with the 3801
    providing the input to the tweeter would make them
    sound yet better?
    I haven't tried it yet.
    Is there any reason why this wouldn't work; that is,
    would there be any reason why this wouldn't work BETTER
    than just powering the 3.1TL's from the seperate amp?

    I have a set of monitor 10's that I could be placed behind the
    3.1TL's and hook them up to the denon also. That could potentiall provide a huge sound stage - not that the 3.1's don't do that already. The monitor 10's have the angled stands too... thus, they might be able to project the sound upward better.
    The room is rather narrow and very long.

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    Default rskarvan

    I take it you're talking a HT system here? If yes, I suppose you could try a verticle bi-amp that way if you wanted to............

    If you were asking about a vertical bi-amp in a HS system, I would say no. In this application, you wouldn't want to use amps that are vastly mismatched. In addition to using two compatable amps (similar characteristics) for a verticle bi-amp, it would be recommended to use an electronic crossover too. This way you aren't sending a full range signal to both halfs. I believe most audio circles recognize this approach to verticle bi-amping.

    Other than that, everyone is free to experiment.

  12. #12

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    Well, I thinkk I found a nice muscle amp for $675.00 The Parsaound HCA-3500. 350 watts. That should get those drivers moving! Anyone ever heard this amp? Soupbone

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