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Newbie needs help on Audio Research and DynAudio Quality


Hello all,

 

I am a newbie to high end home audio and need help from all of you audiophiles out there. I was actually into high end car audio back to when I was younger so I kinda understand what sound quality level can be considered at audiophile standard. I bought this set up (2 mono amps Audio Research Classic 120, Audio Research LS22 preamp, Dynaudio Contour 1.8 mkII, Rega Planet CD player) 4 years ago and did not have time and room to put them up to enjoy until recently. After setting them up last week, I was very disappointed at the performance. The sound was harsh and I would get tired after listening to 2-3 songs. I remember when I picked up the speakers, the previous owner played a couple of songs using his turntable and it was warm, clear and enjoyable (I could not remember what equipment he had back then). I have another set of solid state stuff to play around which includes Luxman M-12 amplifier, Sansui CA-2000 preamp, JBL 4311B, and same CD player Rega Planet. The sound quality is much better compared to ARC set. I expect that the ARC set at least has to be at entry level of audiophile but what I got out from it is disappointing. I need help from you experts to point out what is wrong or what I should expect from Audio Research.

Best Regards,

Dan


sqlover
almarg's avatar
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almarg
9,670 posts
 
Hi Mapman,

I see the statement you are referring to, which says:
Output Regulation:  Approximately 0.2 dB 16 ohm load to open circuit (Damping factor approximately 45)
Like most tube amps, the Classic 120 is presumably designed such that the output tubes see a load that is the same or similar when a 4 ohm load is connected to the 4 ohm tap as when an 8 ohm load is connected to the 8 ohm tap, and as when a 16 ohm load is connected to the 16 ohm tap.

To accomplish that, it can be shown that ideally the output impedance of the 4 ohm tap would be half of what it is for the 8 ohm tap, which in turn would be half of what it is for the 16 ohm tap. Ideally that would result in the damping factor being the same for all of the taps. Various factors will cause some differences between the three damping factors, especially when the output impedance is very low, but they will usually be in a similar ballpark.

And given that a damping factor of 45 for the 16 ohm tap corresponds to an output impedance of 16/45 = 0.36 ohms, and the fact that the output impedance of the 4 ohm tap is almost certainly lower than that, it seems safe to say that interaction of the amp’s output impedance with the impedance variations of a speaker whose minimum impedance at any frequency is 3.8 ohms will not be significant.

Best regards,
--Al
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
To the OP:  Just to be sure that something simple isn't being overlooked, are you sure that the two speakers are connected with the same polarity, i.e., speaker "+" to the amp's 4 ohm terminal and speaker "-" to the amp's "0" terminal?

Best regards,
-- Al
mapman's avatar
mapman
22,389 posts
 
Almarg yes one can presume that is the case and most likely should be just not clearly identified in that spec as written.

If if everything is properly connected and working properly including broken in as you alluded to earlier then it just may be that is not the right amp for that particular user.

OP it has nothing to do with quality of ARC gear in general FWIW. All ARC amps are different and this may just not be the right one for you if things continue as is currently. Break in of amps and speakers is a real phenomenon. Maybe that would help. If not consider a different amp for comparison. Something high power and high current. I’d recommend Trying a newer high quality class d amp if it comes to that. Give the Luxman a shot if not already. That might do just fine.
sqlover OP
2 posts
 
Thanks everyone for spending time putting in comments.

To almarg: Speaker polarity is correct as I double checked per your recommendation.

To mapman: I checked the Luxman spec and it is only for 8-ohm speakers. Not sure if I can connect the Luxman to Dyn?

To ALL:
I have turned the amps on and let it run for the last 12 hrs. During that time, I kept playing CD to CD at low volume level just to have some signals running through the whole system. During bed time, I just left them on (including the preamp). I have also played around with speakers position. This morning, before going to work, I played some song and saw that the quality has improved. Also, I checked and see one of the big tubes in one of the amp is not lighting up. So I will do this to clear things out:
- Have the amp and premap serviced
- after that, play around more with speaker positions since I have a weird corner to set up my gears. Please see picture
 

Put I really think that my amps are not for Dyn speakers. I will try with JBL speakers to find out.

Again, thanks everyone for helping me, I really appreciate it.
Respectfully.

mapman's avatar
mapman
22,389 posts
 
The JBLs listed nominal impedance is 8 ohm. The Dynaudios 4 ohm. I do not see an output impedance spec for the Luxman amp but its a safe bet being a SS amp that it is low and not an issue that would prohibit its use with 4ohm nominal speakers. This is of course as always assuming the amp is in decent working order.

The JBLs are likely an easier load to drive, but you can still use most any SS amp with 4ohm nominal impedance speakers safely. As always, just do not overdue it. Start at lower volume and go up gradually. If you hear signs of audible noise or distortion turn it down. Also check to make sure the amp is not getting too hot in that it will have to work harder into a 4ohm load than with 8.



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