Amps

Lawnguy54

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.

pitdogg2

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.

pitdogg2

Parasound
Carver
Sunfire
Krell
Adcom
Aragon
Etc
Etc
Etc

mhardy6647

"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

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?

GlennDog

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

Lawnguy54

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

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

Perhaps something like this one?

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!)

Lawnguy54

Attached is front and back of my RCA. There is not a switch on the back with the ohms.

pitdogg2

That is a receiver, not an amp. There's also no preouts to facilitate an addition of a stand alone amp.

Lawnguy54

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

OK that is, indeed one of the Radio Shack era RCA receivers.
STA-3900


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.



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.



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

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.





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

Just stop trying to run four speakers simultaneously off a crappy ancient receiver. It's not difficult.

mhardy6647

I agree with every word -- except ancient.




(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.

Lawnguy54

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

Why are you trying to listen to 2-channel stereo music through 4 loudspeakers?

Lawnguy54

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

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.



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



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.

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

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

mhardy6647

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.




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".

Lawnguy54

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

If you had a decent integrated amp you would only need 2 speakers

gp4jesus

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

Clipdat

You can lead a horse to water...

mhardy6647

Yeah, I think we've done what we can do here.

Lawnguy54

Thanks for the helpful advice.