amp for lsi 15

speedy76speedy76 Posts: 2
Let me begin by saying that what I know about ohms, amperes, and GE lightbulbs could fill a thimble.

I inherited (free) a lovely pair of Polk Lsi 15m speakers and a non functioning Marantz 2270 receiver and a functioning Yamaha RX 586. I already owned a Sony 7.1 DN 860, and a Sansui TU 9900 presently used with my Sonus Faber Grand pianos. I will attach a subwoofer to my Polk in due time.

The issue of 4 ohm versus 8 ohm confuses and scares me. Which receiver should I be using and which amp, if any, should I look for? Is tube a better choice for classical music and opera? Do I need a pre-amp as well? I don't want to go cheap but not very expensive either. Thank you in advance.


  • FestYboyFestYboy Posts: 2,979
    Oh my, well I think starting with basics. Load (as seen by the amp) is measured by ohms. Using a resistor, the amp will see a steady load (relative to it's temperature), but a speaker presents a dynamic load and can (does in many cases) dip far lower than their DC resistance or impedance measurement (also listed in ohms). In this case, the lower the number, the greater the load on the amp. It's a bit confusing because as the number drops, the amount of current that can pass through the load (in this case, the speaker) goes up because there's less resistance, but in this case, lower resistance is bad because all the current has to pass through the amp as well and it has it's thermal limits. Think of it like this: the closer you get to 0, the closer you are to welding, which as you know means ALOT of heat.

    So, you want to have an amp that is stable to the lowest limits of the speaker you plan on using. Some 8 ohm speakers can dip to less than half that number (SDAs come to mind). That's why you'll hear want for a high current amp that is 4 ohm stable. They can handle the thermal load and can drive the speakers to their capabilities.

    The tube vs solid state debate has no affect on the above statements.

    Then there's the confusion with receiver, amps, pre amps... Unless you're looking for a specific sound, mixing receivers, amps and pre amps will cause more headache. A receiver is an all in one option. Everything but the source is in it: pre amp, volume control, amplification. An amplifier needs a pre amp for source and volume control.

    The LSi 15s shouldn't need additional sub reinforcement.
  • tonybtonyb Posts: 30,161
    Neither the Yamaha or the Sony will be able to drive the LSI's. What you need is either a receiver with preouts to add an amplifier, or a pre amp/amp combination. Depending on if this system will be for music or HT...OR BOTH.
    HT SYSTEM-2 channel
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Dynaudio Audience 72
    Polk FX500 surrounds
    Cary xciter dac
    Cullen modded Sonos
    Joule la-100 pre
    B&k Ref 4420 amp

    Acoustic zen Satori speaker cables
    Acoustic zen Matrix 2 IC's
    Analysis plus crystal oval ic's
    Wireworld eclipse 7 ic's
    Audio metallurgy ga-o digital cable


    Sonos zp90
    B&k 1430
    Tad 803 speakers
  • mrlorenmrloren Posts: 1,581
    Welcome to the Club,

    What Tony said. You will need an amp with either a good AVR that has pre-outs or a preamp. It's all about how much you want to spend and how big of a system do you want.
    When I was a kid my parents told me to turn it down. Now I'm an adult and my kids tell me to turn it down.

    Family Room:
    Samsung UN60H,
    Denon AVR-X4400H, Emotiva XPA3 GEN3
    Oppo BDP-93,Sony UBP-X800BM, Sony DVP-NS3100ES, WD Live HUB.
    Main: Polk Signature S60
    Center: Polk CSi-A6
    Front High/Rear High In-Ceiling Polk 80F/X RT
    Surrounds: Polk T15
    Sub: HSU VTF3-MK5

    Bed Room;
    Sony KDF-E42A10,
    Marantz SR5010, BDP-S270
    Main: Polk Signature S20
    Center: Polk Signature S35
    Rear: Polk R15
    Sub: HSU STF-2

    Working Warehouse;
    Sony 2100ES
    Polk RTi4 about 15' up the wall
    Old sony 12" Sub
    Mini tower PC with 400GB of music
  • speedy76speedy76 Posts: 2
    thank you all for your advice. I have ordered the hegel 160 pre amp/amp, and the NAD C427 FM tuner.

    here is a very silly question. As I had said, I have recently inherited these lovely speakers, and I was reading the manual on the internet as to how they should be positioned. If each speaker is considered a left or a right, where does the side speaker (woofer) face, toward each other or facing the outside walls? I think I have them reversed! Thanks everyone, more silly questions to follow I am sure.
  • mlistens03mlistens03 Posts: 2,324
    edited March 20
    Outside walls if they are the same as the 25s. The tweeters face in towards you. Look on the back near the serial number and it will say something like model LSi15 R (or L, depending on which one you look at).
    Edit: I was wrong before, it will look like this except it will say 15 instead of 25:

    Main system: Technics SL3200, Shure M97xE, Lafayette LR1100 for tuner, Hagerman Audio Labs Bugle 2 phono stage, NAD C352 integrated, Boston Acoustics VR 2, Boston PV500, generic ICs, and BJC Belden speaker cables.

    Desktop: Dell Precision 690 running iTunes, Yamaha RX-v665, Monitor Audio R90s, Velodyne VA-907, generic ICs and speaker cables.
    I've always thought the goal of high-end audio was not to have your neighbors bang on the wall and say, 'Turn that darn music down' but to have your neighbors bang on the wall and say, 'Tell your friends to go home and you can practice later this week'.
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