amp for lsi 15

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.

Comments

  • FestYboy
    FestYboy Posts: 3,861
    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.
  • tonyb
    tonyb Posts: 32,902
    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-
    Sony 850c 4k
    Pioneer elite vhx 21
    Sony 4k BRP
    SVS SB-2000
    Polk Sig. 20's
    Polk FX500 surrounds

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

    Kitchen

    Sonos zp90
    Grant Fidelity tube dac
    B&k 1420
    lsi 9's
  • mrloren
    mrloren Posts: 2,454
    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:LG QNED80 75", Onkyo RZ50 Emotiva XPA3 GEN3 Oppo BDP-93,Sony UBP-X800BM. Main: Polk LsiM 705Center: Polk LSiM 704CFront High/Rear High In-Ceiling Polk 80F/X RT Surrounds: Polk S15 Sub: HSU VTF3-MK5
    Bed Room; Marantz SR5010, BDP-S270Main: Polk Signature S20Center: Polk Signature S35Rear: Polk R15 Sub: SVS SB2000
    Working Warehouse; Yamaha A-S301, Sony DVP-NS3100ES for disc Plok TSX550T SVS PB2000 Mini tower PC with 400GB of music
  • speedy76
    speedy76 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.
  • mlistens03
    mlistens03 Posts: 2,767
    edited March 2018
    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:
    87hujvxpfypd.jpg