AR 2ax matched with Yamaha CA 800

[basshockey13]

Afternoon Everyone

I’ve wanted a pair of Acoustic Research AR 2ax speakers since I first heard “Pretty Hate Machine” through my Uncle’s at Keuka Lake in 1993. He had a Sansui 4000 receiver and a Sony cassette deck, and it sounded better than any stereo I’d heard to that point. I now have a Yamaha CA-800, and my wish of owning a pair or 2ax has been granted! However, I’m very disappointed. I know that the “Type A” setting is only 10W+10W of output, but even with the B mode selected, it’s awfully quiet. The pots need a bit of work, and the woofers will probably need a refoam, but do I just simply lack the power to drive these speakers? I’m listening to exclusively vinyl on this system. Any input would be greatly appreciated.

Tim

 

[RxDx]

Yeah, you need at least 20w to wake them up, a lot more if you really
want to hear what they can do.

Make sure they don't need new surrounds, or that they get new ones,
before you use them.

 

[basshockey13]

Thank you! Not sure what I’m going to do with them now, but dont want to part with them. We shall see! Perhaps I can find a CA-1000.

 

[spark1]

The CA-800 and the Sansui 4000 have the same rated power output (45 watts). If your CA-800 is unable to achieve anything beyond low volume, there is something wrong (even if you are running it in its 10 watt, Class A mode). There are three basic possibilities:

1. The amp has a problem. You might want to use its preamp out capability to see if it works correctly thru a different power amp, and use its power amp-in capability to drive its power amp section with a different preamp, to see if that changes things. Problem may also be just in the phono section, assuming that this the only input you have tried.
   
2. Your phono input is a problem....possibly too low. What turntable and cartridge are you using? Try using a different source device (CD player, etc) into the AUX connection. Do you get significantly higher output from speakers in this scenario?
3. The speakers have a problem...altho this is least likely. It would be very odd for both speakers to have the same specific problem with low output.

 

[spark1]

On a more general note, you should be aware of the relationship between power, loudness and speaker sensitivity.

First, each 3 decibel (dB) change requires a doubling (or halving) of power. 3dB is generally considered to be the smallest change in loudness to be obvious to someone with average hearing. So, an amp capable of 70 watts of continuous (RMS) output - like the CA-1000 - can put out less than 3dB more loudness than the 45 watt CA-800. This should make it clear that power is not your problem.

To better illustrate the relationship between loudness and power: 80 dB is twice as loud as 70dB, and requires almost 4x the power. 90dB is 4x as loud as as 70dB, and requires approximately 8x the power.

Then there is the issue of speaker sensitivity. Different speakers will achieve different levels of loudness with the same amount of power. Low sensitivity speakers require more power than high sensitivity speakers to achieve the same loudness. The sensitivity rating of a speaker tells you how loud the speaker will get (in decibels) with 2.83V of input, measured at 3 feet. 2.83V = 1 watt, assuming 8 ohm speakers (like the AR2Ax).

The AR2AX has a sensitivity of around 86dB...a bit lower than the average speaker. But even at a listening distance of 12 feet, you should be able to achieve around 75dB with just one watt of input. While not loud, this is not particularly quiet, either.

 

[basshockey13]

Thank you greatly! That was super informative and I’ve never had dB explained to me more clearly. In my line of work, coating holidays are measured in dB, and similarly, a defect of 80dB is twice a 70dB indication, once its normalized for attenuation and current output. I didn’t know it worked the same with amplifiers, although it certainly makes sense.

I have two sets of speakers that sound great with my Yammy: a set of Technics SB CR-33 stacked on top of a pair of MCS 8265s. I can really crank these on Type A, and they sound fantastic.

When I connected the ARs, even in B, it was very quiet. Could these speakers be complete lemons?

 

[spark1]

Well, have you taken off the grilles and confirmed that all of the drivers are working. The woofers should be fairly obvious. A paper tube can be helpful with mids and tweets.

Also, when you were using the other speakers, was it with a turntable? The same turntable as now, and same cartridge?

 

[basshockey13]

Yes, same turntable and cartridge. It’s a Sony turntable from the 80s. I did the paper roll tube truck, and although both sets of tweeters work, one mid is out. The woofers appear to be working, but definitely need to be refoamed.

 

[spark1]

Sounds like the speakers are definitely the problem. Pull that midrange and test with a digital meter (DC resistance). Could be the driver, or a problem with crossover (bad cap). And of course get new foam...they will have quite a bit less low end if the foams are missing or have large gaps. Also, you can damage the woofers running them with damaged surrounds.

Still, it seems like something else is going on if both speakers have approximately the same output, and its dramatically less than your other speakers.

 

[basshockey13]

Thank you for being so gracious with your time and knowledge. I work six days a week, so on Saturday I’m going to dismantle one of the speakers and start looking at the innards. I will be armed with a Fluke, Detoxit, Lone Stars, and some mighty tunes! I’ll post the results!

 

[spark1]

Good luck isolating the problem(s). While the silent midrange could be a function of disconnected wiring, a failed or failing potentiometer, a failed cap, or a failure within the driver itself, I cannot think of a scenario in which both cabinets can only put out low volume. Actually, I can....but only as a function of problems with the amp or source. However, I think you've ruled that out as a possibility.

Wait...there is another scenario in which this could occur....very, very long wiring runs using very thin wiring. But I highly doubt that this is your situation?

On a related note...I guess that both woofers could have a damaged coil, causing exceptionally high resistance (impedance) and therefore low output. I've seen this before, but not in both woofers (altho it is certainly possible). Since you will have the woofers out anyway, test their resistance. Should probably be between 5 and 6 ohms.