Two receivers one speaker each?

[MushroomHunt]

Hey all, I’ve got two matching sx-680’s. They’re a little low on power...95 Watts total, about 45 per channel. Any reason I can use both, with my turntable?...hook the right RCA into one and the left RCA into the other...run one speaker out the left channel on a receiver and a speaker out the right channel of the other receiver. Then pan the balance accordingly? Would this give me the entire 95 watts for each speaker?

 

[swechsler]

No, that won't improve things. Each channel is limited by its design, and not using one channel will not cause the other to suddenly have double the power.

There are some amplifiers that allow you to bridge two channels to double or triple the power by bridging two adjacent channels, and I think some old quadraphonic receivers may have done this as well, when used in two-channel mode.

 

[century tek]

With what you are proposing to do would not give you any more power. Basically, you are just using one half of each receiver/amplifier which will give you the same output as if you were using a single receiver.

The only way to get each receiver to output its full left & right amps to a single speaker, you would need to bridge the receivers so they act like a mono receiver each. Unless the manual for this particular receiver says that they can be bridged, then that is the way I would go but I don't think these receivers can be bridged so the only other option is to get a second set of speakers and use both receivers together for more power.

 

[quiet]

What about the main power supply. Would it not be taxed less?

 

[imral3]

They’re a little low on power...95 Watts total, about 45 per channel

Why do you think these are low on power? What speakers do you have? How large is the room?

 

[spark1]

If you need more power - assumedly so that you can drive your speakers louder - get a different receiver (or integrated amp, or preamp+power amp), OR, get more sensitive speakers.

And keep in mind that it takes twice as much power to get a 3dB increase in loudness (3dB is generally defined as the smallest change in volume to be clearly noticeable...a 10dB change = twice as loud, and requires 8 times as much power).

Your 680, like any stereo amp, has two amps - one for the right channel, and one for the left. In the 680 (and most receivers), the power supply for the amps is shared. Each of these amps is rated to be able to deliver 30 watts of continuous output into an 8 ohm load.

Whether you use two receivers or one, the power available for each speaker is therefore the same....30 watts, assuming 8 ohm speakers (slightly higher with lower impedance speakers).

While true that by using two receivers the common power supply is not shared, this will not provide an appreciable difference in output.

 

[Harvestor]

Hey all, I’ve got two matching six-680’s. They’re a little low on power...95 Watts total, about 45 per channel. Any reason I can use both, with my turntable?...hook the right RCA into one and the left RCA into the other...run one speaker out the left channel on a receiver and a speaker out the right channel of the other receiver. Then pan the balance accordingly? Would this give me the entire 95 watts for each speaker?

Get yourself a Sansui AU717 with Dual Transformers one for the Left channel one for the Right channel...
Or a Kenwood Basic M2-A Amplifier which also has separate Transformers...
Here's my video showing the inside of the 717 ...Left of Amplifier has the Two Transformers with the Sansui name on them

 

[quiet]

Can each receiver be set to mono and the L and R be joined from that receiver and be sent to one speaker? And the same with the other receiver for the other channel?

 

[spark1]

Dual transformers may well provide performance benefits, but why does the OP need either of the amps you are recommending?

He first needs to determine how much power he needs....a function primarily of how loud he wants to be able to listen, speaker sensitivity, and listening distance.

He can then start looking for appropriate amplification. If he feels compelled to pursue amps with dual power supplies, or even mono amps, there are plenty to choose from...both used and new.

 

[spark1]

Can each receiver be set to mono and the L and R be joined from that receiver and be sent to one speaker? And the same with the other receiver for the other channel?

No.

Or more accurately, yes, if he wants to create a high likelihood of damage to his receivers.

In addition, this arrangement would not provide stereo output (for the few moments before one or both amps melt down). It would be mono.

 

[quiet]

I have a pair of Lafayette LR 1500ta receivers. I'm gonna give it a go and see if the smoke comes out.
The only remarkable thing about these receivers is the amp protection system.

 

[twiiii]

First of all you can't hear a 3 db change (if possible, which it is not in this case,) with out a reference unless you have trained hearing. Musician, etc. So don't waste your time. For me I would be looking for more efficient speakers more power, or both. That said for over 10 years I just had about the same power with 101 db plus sensitivity speakers and I had plenty of level. 117 db with 40 watts at 4 ft.each channel. If I would have had 100 watts I would have had 121 db. People now days by speakers that require 1000 watts to get the same levels I got with 40. No wonder I some times think the world is going mad.. . .

 

[spark1]

First of all you can't hear a 3 db change (if possible, which it is not in this case,) with out a reference unless you have trained hearing. Musician, etc. So don't waste your time. For me I would be looking for more efficient speakers more power, or both. That said for over 10 years I just had about the same power with 101 db plus sensitivity speakers and I had plenty of level. 117 db with 40 watts at 4 ft.each channel. If I would have had 100 watts I would have had 121 db. People now days by speakers that require 1000 watts to get the same levels I got with 40. No wonder I some times think the world is going mad.. . .

First of all, yes, most people can. In fact, within the field of audiology, it is broadly accepted that a 3dB change is the smallest to be obvious to someone with normal hearing capabilities. On a more technical level, a 3dB change = a 23% change in perceived loudness (and a 100% change in sound energy, or intensity).

However, if you listen at the levels you described, I am not surprised that you are unable to discern a 3dB change loudness. Your hearing will have been irreparably damaged.

 

[fill35u]

No.

Or more accurately, yes, if he wants to create a high likelihood of damage his receivers.

In addition, this arrangement would not provide stereo output (for the few moments before one or both amps melt down). It would be mono.

Each SX-680 could be series bridged with its own BTL adapter. That might get around 90W per channel into 8R speakers. No reason to expect anything would burn up.

 

[spark1]

Yes, with two adaptors he could get two 60 watt amps. This is not what was being described.

He would also need to put in place a means of feeding sources to both amps.

 

[spark1]

I have a pair of Lafayette LR 1500ta receivers. I'm gonna give it a go and see if the smoke comes out.
The only remarkable thing about these receivers is the amp protection system.

Please report back with your findings.

 

[Harvestor]

Dual transformers may well provide performance benefits, but why does the OP need either of the amps you are recommending?

He first needs to determine how much power he needs....a function primarily of how loud he wants to be able to listen, speaker sensitivity, and listening distance.

He can then start looking for appropriate amplification.

Dual transformers may well provide performance benefits, but why does the OP need either of the amps you are recommending?

He first needs to determine how much power he needs....a function primarily of how loud he wants to be able to listen, speaker sensitivity, and listening distance.

He can then start looking for appropriate amplification. If he feels compelled to pursue amps with dual power supplies, or even mono amps, there are plenty to choose from...both used and new.

I was thinking the original poster would be better off getting the type of amplifier like I suggested, because their questions seemed imply using two receivers and separating left and right channels in such a manner would increase power output to the individual speaker.
I figured this was a better approach...

And I should also have said maybe they should just get more efficient speakers that will make a 45 watt per Channel receiver more appealing if they're searching for more power or louder listening sessions

 

[spark1]

His SX-680 is rated for 30 watts into 8 ohms and 37 watts into 4 ohms...not 45.

In any case, there is nothing about dual transformers/dual power supplies that results in a more powerful amplifier.

Regardless of amp topology, it comes down to desired loudness at a given distance and speaker sensitivity. From this info, the necessary amplifier power can be determined. Alternatively, he can calculate the speaker sensitivity required to achieve desired loudness with his 30 watt amp.

Simply put, if he can't get the loudness he wants with his existing system, he needs to get more sensitive speakers, a more powerful amp, or both.

Alternatively, he could add a second pair of matching speakers in parallel and pick up another 3-6dB, assuming the amp can handle combined load. And then add a couple of subs for a few dB more. But running two pairs of speakers comes with its own challenges.

 

[Sam08861]

Not sure what kind of speakers you have, but you could look into bi amping. One receiver would drive the woofers, another the tweeters. You would need a crossover though.

 

[cpt_paranoia]

An amplifier's ability to drive power into a load is determined by the available voltage swing (provided it can also supply the necessary current to meet that swing). P=V^2/R

The amplifier power supply is at a fixed voltage (except in some esoteric classes of amplifier). The amplifier can only swing the output within the range of its power supply.

A stereo amplifier has two amplifier circuits, one for left, one for right. Both swing the output within the range of the power supply. An amp rated for a given power can drive both channels with that power; the power supply is capable of providing current to do that.

If you don't use one channel, the power supply voltage is still the same. The amplifier cannot swing the output any further. It cannot drive any more power into the single load. The only change is that you don't take as much current from the power supply.

The only way to increase the output power with the same power supply is to use the two channels in bridge mode, where the input to one channel is the inverse of the signal fed to the other channel, and the speaker is connected across the outputs of the two amplifier channels. This doubles the effective swing seen across the load.

Not many hifi amps have bridge mode capability.