Amps

I have an RCA 100 watt Amp that I have hooked to 2 Polk 705s and 2 Bose 301s. If I have all 4 speakers playing, it is not very loud. Need more power. Any suggestions for an AMP that will push out more sound.

Best Answer

  • pitdogg2
    pitdogg2 Posts: 24,474
    Answer ✓
    Lawnguy54 wrote: »
    I hear you then what receiver do you think I need (size) for 4 speakers? Or will I have the same problem of sound from two to four speakers.

    The problem is most receivers now are rated to drive ONE pair of speakers at the stated WPC. Many home theater receivers drastically reduce WPC with more than ONE pair of speakers. Since the power supply is typically the MOST expensive part of a receiver that was the first part to get scaled down to keep costs in line. Many HT receivers rated at lets say 140wpc are down to 40-50 WPC or less with 5 speakers. Not only has the WPC dropped but more importantly the CURRENT to drive said speakers falls flat and that is how it is so easy for the receiver to send CLIPPED signal the speakers and that is what actually causes harm to tweeters and drivers in the speaker.
    Your best bet is to buy a decent receiver that has 5.1or more PRE-OUTS for other channels then you can buy a good amp to be able to drive the speakers to the best of your ability.

Answers

  • pitdogg2
    pitdogg2 Posts: 24,474
    Parasound
    Carver
    Sunfire
    Krell
    Adcom
    Aragon
    Etc
    Etc
    Etc
  • mhardy6647
    mhardy6647 Posts: 32,923
    edited January 2022
    "not very loud" isn't, typically, an issue of inadequate power per se, but rather of inadequate drive (signal strength) of the component providing a signal (music!) to the amplifier.

    Can you give us a little more information?
    RCA Amp as in late Radio Shack-era "RCA" or otherwise?
    Two channel (stereo) intergrated amp or receiver?
    What is your signal source (e.g., a phone, a media player, or a CD or DVD player)?

    You may well need "more power" but that's probably not why your setup is "not very loud".

    All four loudspeakers playing at the same time may well present a really difficult load for the amplifier. Does it sound strained or distorted when playing all four? Maybe (???) the amplifier has some sort of load protection that is limiting its output into all four. Does the setup play louder when only driving one pair of the speakers (either pair) and then get less loud when both pairs are playing at the same time?
  • jbreezy5
    jbreezy5 Posts: 1,141
    To tack-on to @mhardy6647 post, maybe begin with only the Polks connected (should be the better of the 2 pairs of speakers you have.

    How is the sound with just those connected?
    CD Players: Sony CDP-211; Sony DVP-S9000ES; Sony UDP-X800M2 (x2); Cambridge Audio CXC

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  • GlennDog
    GlennDog Posts: 3,084
    I've got a sweet Adcom 5802 that'll make those 705s sing hallelujah

    https://worldradiohistory.com/hd2/IDX-Audio/Stereophile-IDX/IDX/90s/Stereophile-1998-04-IDX-217.pdf
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  • Not Radio Shack I think it was Best Buy about 16 years ago/ my RCA has A or B or both. Does have FM & AM I guess all in one. It is lower in sound when I play all 4 speakers and yes it is higher in sound with just 2 speakers playing. I use this for phono plus streaming music.
  • mhardy6647
    mhardy6647 Posts: 32,923
    You know -- I still cannot rationalize this.
    Do you have a model number for the product (which sounds like a receiver).
    A model number would help a lot.
    A clear photo of the rear panel of the receiver could help, too.

    Does it have a speaker impedance switch on the back? Labeled, perhaps, with something like "8 ohm/4 ohm"?

    We would like to help -- so please help us help you with some more info!


  • mhardy6647
    mhardy6647 Posts: 32,923
    Perhaps something like this one?
    16rlhrc3f12f.png
    https://www.ebay.com/itm/334284001917?hash=item4dd4e1127d:g:UiIAAOSwIQhh2f5U
    The model number suggests this model is from the days when Radio Shack was selling components branded "RCA".

    (I am clutching at straws here!)

  • Attached is front and back of my RCA. There is not a switch on the back with the ohms.
  • pitdogg2
    pitdogg2 Posts: 24,474
    edited February 2022
    That is a receiver, not an amp. There's also no preouts to facilitate an addition of a stand alone amp.
  • What would you suggest then to push my four speakers. The room size is a 25x26. I am just wanting something that will push out thru the 4 corners.
  • mhardy6647
    mhardy6647 Posts: 32,923
    OK that is, indeed one of the Radio Shack era RCA receivers.
    STA-3900
    gcwkogy181ge.jpg

    The manual's available: https://www.hifiengine.com/manual_library/rca/sta-3900.shtml
    "100 wpc" per FTC regs -- but not a really robust 100 wpc.
    note the power spec bandwidth of 40 Hz to 20kHz.

    i5sw23dpybem.png

    You are probably just asking more of it than it can deliver @Lawnguy54
    Note the manual's admonition to "only connect speakers that are rated at between 8 and 16 ohms"
    This is an amplifier with limited -- perhaps severely limited -- output current capability and thus not one well-suited to low-impedance loads.

    bhpg9o3qk3zq.png

    Even two pairs of 8 ohm speakers connected to A & B outputs and both turned on at the same time represent a nominally 4 ohm impedance load to the amplifier in your receiver. It is probably pretty unhappy with that condition. Lower impedance loudspeakers would make the situation even worse, and could result in damage to the amplifier.

    Also, given the age (and relatively low quality) of the receiver, the power supply section may not even be capable of performing "at spec", so the performance of this particular receiver, at the age of 20 years old, may be even considerably worse than when it was new.

    Best thing to do: if you like the speakers you have and if you really want to run both pairs at once -- get a newer, better, and perhaps even more powerful stereo amplifier.

    You might well want to consider an integrated amplifier, which has all of the inputs and controls of a reciver, without wasting your money (or comprimising the performance of the component even further) by also including an AM/FM tuner.

    A good used component would be fine, or a refurbished model, if cost is a major concern. There are many websites that sell such "deals" (sometimes even refurbished by the manufacturer) even with a limited warranty for a good price.




  • mhardy6647
    mhardy6647 Posts: 32,923
    Oh. two other things.

    1) thanks very much for posting the photos! Solved the mystery!

    2) it is essential that there are no inadvertent short circuits between any of the eight wires that comprise the two pairs of stereo speaker connections! The small clearance between connections on the back panel, and the twists in the wires in your photo, make me a little nervous that you may have a stray wire strand crossing from one connection point to another. THAT could be part of your problem, too -- maybe even the whole problem.

    pc4fkv8lcn7i.png

    36eu4ytnmv0r.png

    If you haven't done so already, you might want to disconnect everything, carefully re-dress all of the speaker wire leads, and carefully and thoughtfully re-connect them.

  • Clipdat
    Clipdat Posts: 12,557
    Just stop trying to run four speakers simultaneously off a crappy ancient receiver. It's not difficult.
  • mhardy6647
    mhardy6647 Posts: 32,923
    edited February 2022
    I agree with every word -- except ancient.

    :#

    14431883336_686a0060ef_c.jpg
    (not that these, at ca. 10 watts each, would do too well with that particular collection of loudspeakers)

    Bottom line, there are two straightforward solutions. Different, better/more capable receiver (or amplifier), or less loudspeakers.



  • I hear you then what receiver do you think I need (size) for 4 speakers? Or will I have the same problem of sound from two to four speakers.
  • Clipdat
    Clipdat Posts: 12,557
    Why are you trying to listen to 2-channel stereo music through 4 loudspeakers?
  • Like a Yamaha 801 or larger? To run all four of my speakers? With no sound loss or am I just dreaming! You may not know ; Thank You. See I do not want to be in the same situation when I buy a new receiver so I talk things out.
  • mhardy6647
    mhardy6647 Posts: 32,923
    edited February 2022
    The Yamaha A-S801 integrated amplifier is a very nice & capable piece of hardware.
    That said, Yamaha's ratings for running two pairs of loudspeakers on it are quite conservative, specifying both pairs of loudspeakers must be at least 8 ohms nominal impedance and instructing the use of a "low impedance" switch on the back of the amp. This switch, to the best of my understanding, limits the current (and thus power) output of the amplfier into a low-impedance load.

    xxngtgqogpe8.png

    https://usa.yamaha.com/files/download/other_assets/1/1412681/web_VEX7500_A-S801_om_U_EnFr_A0.pdf

    s3a7bdoh6a7y.png

    The A and B speaker connections put both pairs of speakers in parallel across the power amp output of each channel, so the load the amp feels is (nominally) 4 ohms.

    ur3j7btjcw13.png
    Clipdat wrote: »
    Why are you trying to listen to 2-channel stereo music through 4 loudspeakers?

    so, let's try this question again, @Lawnguy54 -- why do you want to use all four loudspeakers at the same time?
  • gp4jesus
    gp4jesus Posts: 1,969
    Anyone consider connecting the speakers in series? It’s free and reduces the likelihood him toasting his unit

    I know that presents some technical and possible SQ issues or changes but…

    Have fun. Tony
    Samsung 60" UN60ES6100 LED Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga - LCR mids, inside* & out 8 ga Powerline: LR woofers, inside* & out *soldered LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & “Plugged*” Mids - 981, connected w/MP Premiere ICs Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s *Xschop's handy work
  • mhardy6647
    mhardy6647 Posts: 32,923
    edited February 2022
    One may certainly connect loudspeakers in series.
    The problem is that it passes the signal through the inductance, capacitance & resistance of one loudspeaker system before it gets to the other one.
    From my perspective, this pretty much guarantees that the second loudspeaker in line will not perform as its designer and manufacturer intended.

    It will also decrease the amount of power delivered (e.g., by 3dB if both speakers wired in series are of the same nominal impedance).

    Electrically, though, it will do no harm.
    Doesn't make it a good idea, though.

    @Lawnguy54 (if you're still out there): this is what you'd have to do if you wish to wire your two sets of speakers in series.

    ssoavjjhgrgo.png


    It may (just barely) be worth mentioning that, especially many years ago, some amplifiers or receivers would wire A & B loudspeaker outputs in series. These are virtually unknown today. A receiver with A & B outputs wired in series will produce no sound if only one pair of loudspeakers is connected (say, to the "A" outputs) and the speaker selector is set to "A + B".
  • I listen two one pair of speakers most of the time, as why do I listen to all four because I have set up on the all corners of the room. I need a bigger integrated amp.
  • invalid
    invalid Posts: 1,270
    If you had a decent integrated amp you would only need 2 speakers
  • gp4jesus
    gp4jesus Posts: 1,969
    edited February 2022
    mhardy6647 wrote: »
    One may certainly connect loudspeakers in series.
    The problem is that it passes the signal through the inductance, capacitance & resistance of one loudspeaker system before it gets to the other one.
    From my perspective, this pretty much guarantees that the second loudspeaker in line will not perform as its designer and manufacturer intended.

    It will also decrease the amount of power delivered (e.g., by 3dB if both speakers wired in series are of the same nominal impedance).

    Electrically, though, it will do no harm.
    Doesn't make it a good idea, though.

    @Lawnguy54 (if you're still out there): this is what you'd have to do if you wish to wire your two sets of speakers in series.

    A big thanks to Mark for detailing what I was thinking so well, especially the graphics.

    Since it seems his unit employs current limiting, it’s possible though unlikely using series loading he may have higher volume than the parallel loading, but not to his satisfaction driving a single pair. But…

    …as Mark has taken great pains to point out to which I alluded: SQ will suffer, likely greatly. Lawnguy54: either use the pair speakers of which the sound you prefer or upgrade your gear. Risking the toasting of your present unit’s outputs wired in parallel isn’t worth it especially considering the sale of same could (partially) offset the upgrade cost(s*).
    *”hint”

    @Lawnguy54: make sure the replacement receiver (or whatever) has preamp outputs. As many will agree this seemingly insignificant Feature will greatly broaden your system’s possibilities. Later on you could up significantly up your game w/a pair of splitters and a 4 or 5 channel amp. (Hint: I have a Thx Certified 5 X 100 WPC amp for sale, useless w/out preamp outputs)

    My $0.02. Tony



    Post edited by gp4jesus on
    Samsung 60" UN60ES6100 LED Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga - LCR mids, inside* & out 8 ga Powerline: LR woofers, inside* & out *soldered LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & “Plugged*” Mids - 981, connected w/MP Premiere ICs Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s *Xschop's handy work
  • Clipdat
    Clipdat Posts: 12,557
    You can lead a horse to water...
  • mhardy6647
    mhardy6647 Posts: 32,923
    Yeah, I think we've done what we can do here.
    :|
  • Thanks for the helpful advice.