or Connect
AVS › AVS Forum › Audio › Receivers, Amps, and Processors › Adding a 2 channel amp to power 4 ohm speakers
New Posts  All Forums:Forum Nav:

Adding a 2 channel amp to power 4 ohm speakers

post #1 of 23
Thread Starter 

  I have just purchased a pair of Martin Logan Motion 40, 4 Ohm towers. I'm running them from my old Yamaha R-V1103 80 watt per channel 5.1 receiver.
  I am trying to add a power amp to run the front speakers mentioned above. The Yamaha R-V1103 pre outs are rated at 2.6 volt  /1.1 K-ohms. I'm looking at a Nad C 275 BEE power amp which has an Input Sensitivity of 1.2 volts and a Voltage Gain of 29dB.
 Q.Can the Nad amp do the job with the rated pre out of 2.6 volt coming out of otherwise great sounding Yamaha receiver?

 Q. Should I consider the Emotiva XPA-3 or XPA-2 to do the job?
Does anyone have advise on choosing a Power Amp? I want to achieve 300 watts into 4 ohms.
Speakers
Impedance: 4 Ohm
Frequency Response: 40-25,000 Hz +/- 3 dB
Sensitivity: 92 dB @ 2.83 Volts/ meter
Recommended Amp Power: 20 - 300 watts

Thank you for you're input.
         


Edited by rrollin909 - 12/6/13 at 6:57am
post #2 of 23
Thread Starter 

Can anyone give me some advise on powering 4 Ohm speakers without clipping my AVR?
Seeking an external Amp setup.
You're advise is welcome.

post #3 of 23
The NAD amp you mentioned would be a very good choice. I would certainly recommend it...but:

It is $1300, though, and for $1200 you could get a much better-sounding receiver with plenty of power to drive your speakers; the Cambridge Audio 551R. That is the recommendation I would make to a friend. Cambridge is the Mercedes-Benz of receivers, and their power ratings are far more realistic and conservative than others. IMO the Cambridge 551R would have way more power than you need, but more importantly provide MUCH better sound quality than anything Yamaha has ever made! With the Cambridge receiver, your speakers will sound so much better that they won't be able to wipe the smile off of your face for a week.

It will make all 5 channels sound better. Adding an amplifier will give more power, but not improve the sound of the Yamaha. It will still be screwing up your overall sound quality.

You would NOT need a separate amplifier to drive your speakers with that receiver. It has amplifers and power supplies that have been engineered for good sound quality and maximum speaker drive capability.

Your speakers are actually quite sensitive, at 92 db per watt, and do not require 300 watts at 4 ohms. Even 50 watts at 4 ohms would be plenty of rated amplifier power for those speakers. 10 watts of actual power applied to those speakers will produce a sound level of 102 dbA, which is louder than a live symphony orchestra at close range. I play my system pretty loud, but seldom THAT loud.

Any actual power level over 100 watts would really not be usable with those speakers.

The ACTUAL power output capability of your current receiver is probably about 40 watts per channel when driving 5 speakers (and it should not even be connected to your 4 ohm speakers; it will be unstable with that load).

The 2.6 volts that is specified is only the MAXIMUM voltage the preouts will produce without clipping. Normally they will only be putting out 100-500 millivolts or so, depending on the instantaneous nature of the audio signal. The signal fluctuates with the musical content.

They will work fine with any amplifier.

I'm near San Bernardino here, so hi there...lol.
Edited by commsysman - 12/6/13 at 8:11am
post #4 of 23
Quote:
Originally Posted by rrollin909 View Post

Can anyone give me some advise on powering 4 Ohm speakers without clipping my AVR?

Don't operate your receiver at full output power. Few of us ever do.
post #5 of 23
Thread Starter 

Thank you, commsysman for you're input and recommendation on the Cambridge 551R. I will certainly consider that option. Fortunately I haven't gone out and bought anything yet. I've looked at a lot of Receivers and not many seemed to be able to handle the 4 Ohm speakers.
Thank you again for responding.


Edited by rrollin909 - 1/22/14 at 9:57am
post #6 of 23
Thread Starter 

Thank you FMW for the input.
  I have changed Receiver to a Denon 2313 that I had bought recently. It is rated at 105 watts stereo 2 channel or somewhat less at 7.2. It runs the Martin Logan's fine but when adding my JBL 8-ohm 150 watt rated speakers the receiver gives off a fluctuating /rolling and weak output. Not good.
  Now I'm just using the two JBL's front 2 channel only. Can't run both pairs of speakers at the same time.

  I am still thinking of adding a 2 channel power amp that will handle 4-ohm 150 to 250 watts. I want to run all 4 speakers as front stereo.


Edited by rrollin909 - 1/22/14 at 10:01am
post #7 of 23
My advice is to ignore the ohm rating on your speakers. I have many 4 ohm speakers and they can be driven the same as 8 ohm speakers by any receiver.

The primary difference between a 4 ohm speaker and a 8 ohm speaker is the 4 ohm speaker manufacturer actually took the time and effort to accurately measure it. Do you ever wonder why almost all inexpensive speakers are 8 ohms? It's because the manufacturer is typically a Chinese company that wants the speaker to sell better so they automatically rate it at 8 ohms. Impedance can't be represented by a single number and there's no way to prove or disprove a measurement so manufacturers tend to overstate it.
post #8 of 23
Quote:
Originally Posted by rrollin909 View Post

Thank you FMW for the input.

  I have changed Receiver to a Denon 2313 that I had bought recently. It is rated at 105 watts stereo 2 channel or somewhat less at 7.2. It runs the Martin Logan's fine but when adding my JBL 8-ohm 150 watt rated speakers the receiver gives off a fluctuating /rolling and weak output. Not good.

  Now I'm just using the two JBL's front 2 channel only. Can't run both pairs of speakers at the same time.


  I am still thinking of adding a 2 channel power amp that will handle 4-ohm 150 to 250 watts. I want to run all 4 speakers as front stereo.

I power a pair of 4 ohm speakers in my bedroom with a bottom-of-the-line Pioneer AV receiver with no problems at all. It is all just a matter of how loud you play the system. Amplifier impedance ratings are made at full output power - something very few of us never use. It is a fear tactic to get you to buy a power amplifier. If you want to do that be sure your AVR has preamp outputs.
post #9 of 23
Thread Starter 

Hi FMW, I don't understand why the two pairs of speakers don't run well at the same time on the Denon 2313 av receiver?
  My old Yamaha model R-V1103 Surround receiver ran them well on the A and B stereo Channels simultaneously until I tried to turn the volume up beyond the normal range to see what it could produce. They sounded good on the way up and then clipped. I know that the Yamaha is rated at 80watt per channel 2 channel stereo, and the specs. say it can run 4 ohm, 6 ohm, or 8 ohm.
  Just too much speaker for this Receiver? Still considering my options.

post #10 of 23
Thread Starter 

Thank you for you're input, KidHorn. I am open to all the advice that I can get.
 The place were I am coming from is....I have recently gotten into upgrading my stereo/ av experience. For Music primarily.
 I have Albums and CDs collection mostly. XM radio, not much compressed music.
 I am after clean stereo sound, surround not so much but theater capability also.
 


Edited by rrollin909 - 1/27/14 at 7:22am
post #11 of 23
All amps/receivers more or less sound the same. The most important factor when buying a receiver is the room correction software. Audyssey for Denon/Onkyo/Marantz. YPAO for Yamaha. MCACC for Pioneer. They all basically work the same. Some higher end Audyssey have a more granular eq curve and can eq subs better. XT32 is a step above all the others.

It sounds link you want to be able to play really loud, so you either need to buy a powerful receiver, which would also likely have very good room correction software or you need to buy a receiver with pre-outs so you can hook up an external amp.

Strangely enough, pre-outs tend to only be available on higher end receivers, which also have better amplifiers. So I would suggest buying a higher end receiver with pre-outs and see how it works. If you still need more power, then buy an external amp and hook it up to the receiver.
post #12 of 23
Thread Starter 

Hi KidHorn, to you're comment, yes I want to be able to play music above the normal listening range at times.
  Last August I bought a Denon AVR-2313CI ,7.2 ch. Integrated Network Receiver /rated at 110 watts per channel in stereo 2 channels driven. It has RCA pre-outs for a Zone-2 amp. I'm thinking of using the Zone 2 pre-out to use a Nad C-275 BEE stereo 2 channel amp. It produces a rated 150 watts into 4 or 8 ohms. Then run 1 pair of 8ohm 150 watt speakers from the Denon in stereo mode and the 4ohm ML towers from pre-out Zone-2  from Nad amp . Play all 4 speakers as front stereo side by side and in sync.
  My dilemma is will this do what I want?  Play all 4 speakers as front stereo side by side and in sync, Or do I need to buy a very expensive Receiver that will have to drive  all 4 speakers  ( 2- 8ohm and 2- 4ohm ) I'm looking at the Cambridge Azur 651R, will that work well?


Edited by rrollin909 - 1/29/14 at 4:42am
post #13 of 23
Quote:
Originally Posted by rrollin909 View Post

Hi FMW, I don't understand why the two pairs of speakers don't run well at the same time on the Denon 2313 av receiver?

  My old Yamaha model R-V1103 Surround receiver ran them well on the A and B stereo Channels simultaneously until I tried to turn the volume up beyond the normal range to see what it could produce. They sounded good on the way up and then clipped. I know that the Yamaha is rated at 80watt per channel 2 channel stereo, and the specs. say it can run 4 ohm, 6 ohm, or 8 ohm.

  Just too much speaker for this Receiver? Still considering my options.

When you A pair and B pair together you cut the overall impedance in half.
post #14 of 23
Quote:
Originally Posted by FMW View Post

Quote:
Originally Posted by rrollin909 View Post

Hi FMW, I don't understand why the two pairs of speakers don't run well at the same time on the Denon 2313 av receiver?

  My old Yamaha model R-V1103 Surround receiver ran them well on the A and B stereo Channels simultaneously until I tried to turn the volume up beyond the normal range to see what it could produce. They sounded good on the way up and then clipped. I know that the Yamaha is rated at 80watt per channel 2 channel stereo, and the specs. say it can run 4 ohm, 6 ohm, or 8 ohm.

  Just too much speaker for this Receiver? Still considering my options.

When you A pair and B pair together you cut the overall impedance in half.

IME only stereo receivers have a facility for managing two complete sets of speakers. I went looking for modern AVRs with the feature and came up empty. Some support a second zone but they have either just line level outputs or dedicate some amps to them.
post #15 of 23
Quote:
Originally Posted by rrollin909 View Post

Hi KidHorn, to you're comment, yes I want to be able to play music above the normal listening range at times.

  Last August I bought a Denon AVR-2313CI ,7.2 ch. Integrated Network Receiver /rated at 110 watts per channel in stereo 2 channels driven. It has RCA pre-outs for a Zone-2 amp. I'm thinking of using the Zone 2 pre-out to use a Nad C-275 BEE stereo 2 channel amp. It produces a rated 150 watts into 4 or 8 ohms. Then run 1 pair of 8ohm 150 watt speakers from the Denon in stereo mode and the 4ohm ML towers from pre-out Zone-2  from Nad amp . Play all 4 speakers as front stereo side by side and in sync.

  My dilemma is will this do what I want?  Play all 4 speakers as front stereo side by side and in sync, Or do I need to buy a very expensive Receiver that will have to drive  all 4 speakers  ( 2- 8ohm and 2- 4ohm ) I'm looking at the Cambridge Azur 651R, will that work well?

I think your proposed scheme will in some sense work, but many will prognosticate that you won't be overjoyed with the results because the duplicate speakers will either interfere with each other or will not add that much. Depends on your preferences and rooms and the speakers themselves.
post #16 of 23
I would guess hooking up an external amp to the zone 2 pre-outs would work, but why do you want 2 sets of mains? We're no longer in the 1980's. Why not setup a 5.1 system? I think 5.1 sounds a lot better than stereo.
post #17 of 23
Thread Starter 

Hey KidHorn, I'm going to try setting the system up in 5.1 and see what happens.                  


Receiver,  Denon AVR-2313ci
Front R/L, Marten Logan- Motion 40, 3way speakers
Center, Martin Logan- Motion 30
Rear Surround R/L, JBL- LX 500, 3way speakers
Sub, Infinity Primus- PS410

post #18 of 23
Thread Starter 

Thanks for the insight arnyk.
Maybe I'm going at this all wrong.

post #19 of 23
Thread Starter 

Thank you everyone for input.

I have found it to be very useful to get advise & bounce some ideas around before buying more equipment.
  As suggested I have set up my system into 5.1 mode and implemented the Audyssey room EQ. The system sounds good and all of the speakers that I want to use are sounding great.It seems that the Denon 2313ci is able to drive the Martin Logan 40s 4ohm and JBLs 8ohm in the same system. Getting the sound I had wanted.
 
Thank you AVS Forum

post #20 of 23
Bi-amp mode in most receivers sends identical signals to two sets of speakers similar to stereo speaker
A and B from previous generations. 5.1 is the way to go. The word bi-amp sells product.
Edited by kikkenit2 - 2/5/14 at 8:59pm
post #21 of 23
Quote:
Originally Posted by rrollin909 View Post

Hi FMW, I don't understand why the two pairs of speakers don't run well at the same time on the Denon 2313 av receiver?

  My old Yamaha model R-V1103 Surround receiver ran them well on the A and B stereo Channels simultaneously until I tried to turn the volume up beyond the normal range to see what it could produce. They sounded good on the way up and then clipped. I know that the Yamaha is rated at 80watt per channel 2 channel stereo, and the specs. say it can run 4 ohm, 6 ohm, or 8 ohm.

  Just too much speaker for this Receiver? Still considering my options.

That's a fair question and I don't have a definitive answer. Normally, if an amplifier reaches the point of thermal shutdown, it doesn't vary the volume up and down. It just turns off the amplifier. While each amplifier in the AVR is independent of the others, they all share the same power supply. My guess is that there is something defective or weak in the power supply. You can check that by removing all the speakers except the ones that cause the strange sound presentation. If it goes away, I would suspect a power supply problem. You can eliminate the amplifiers themselves by connecting those speakers to different amplifiers. If the problem persists after all of that, then I would suspect the speakers.

Troubleshooting is just a matter of changing things around to try to eliminate potential causes until you can get down to the actual cause. Adding an external amplifier may or may not solve the problem. Buying one is an expensive way to find out.
post #22 of 23
Thread Starter 

Yes FMW, I have been holding off on buying another Receiver for just that reason $$$.
  I think that I've solved the problem with set up in 5.1 and I've programmed the speakers parameters to front mains (Large) & surround as (Large). Crossover at 80db to Subwoofer. Running Audyssey has solved the problem. All channels not being used are set to (None) so that those that I do run have all of receivers power. "What a difference"
  This should keep me satisfied for now. It sounds like it should now.
For me this is new stuff. Using Audyssey. I've been in a cave for awhile and just got back into the home audio ect.
Thank you all.
 


Edited by rrollin909 - 2/6/14 at 9:41am
post #23 of 23
Glad you got it worked out.
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Receivers, Amps, and Processors
AVS › AVS Forum › Audio › Receivers, Amps, and Processors › Adding a 2 channel amp to power 4 ohm speakers