REL Strata III repair issue

Thanks all for your responses.  Update:

I now have the Strata in a secondary system using an inexpensive outboard amp/xover (NHT).  Getting pretty good (not great) results and the jury is still out on the fate of this Strata.  

Dave, thanks for your thoughts; I will have a local tech check the defective amp module.  Further update:

I have bought a pair of REL Storm III subs as I have always wanted to try stereo subs.  Well, everything they say about stereo subs is true: smoother, less lumpy bass, improved dimensionality and absolutely huge soundstage among other benefits.  So far, I am very pleased with the results, but am trying to diagnose a potential problem with one of the subs.  Although there is no sign of distortion or strange sounds of any kind, one of the subs gives noticeably less output (or has lower input sensitivity) than the other.  For the same level of output that one sub provides with the volume knob at the 2/3-3/4 mark, the other needs to be almost maxed out.  I plan on swapping out the amp modules to make sure that the issue is not with the speaker itself as opposed to the amp module.  I contacted REL about this and they tell me that as long as the sub provides  undistorted sound that there is nothing that they can do; it either works or it doesn't !?!? Thoughts?

I understand your issue completely, frogman. I initially bought one REL Stadium III (cherry finish) and some time later decided to try two. A seller had two black-finish Stadium IIIs for sale for a good price so I bought both since they would match.

One of the black pair responds differently to crossover/volume adjustments than the other (and to the cherry one). I learned to just ignore the marks on the back plate when setting the knobs for lack of a better remedy. I am not any more comfortable with this than you are.

Also had one crap out with symptoms similar to yours. I stole the electronics from the cherry one and swapped it into the offending black one, the cherry one now is an (expensive) podium for the components in my vintage system. So, I have a vested interest in your experiences with correcting the problem(s) with your first sub. Interestingly, the one that crapped out is the one that had the setting variances to the other two.

BTW - the improvements you describe from adding the second sub mirror mine.

Dave

Interesting that you should experience the same issue, Dave.  My two subs came from different sellers and from a cursory examination of the modules it is obvious that, while they are the same design, they are of different vintages.  I removed the modules shortly after receiving them and was able to compare, but didn't swap them at the time as I wanted to first have a better sense of what was happening sonically with each.  I do find it strange that, even if the one that gives less output, is operating "normally" and the difference was a deliberate design change, that it would mean that the volume would have to be almost maxed out in the context of a system that is pretty conventional.  My Manley tube monos currently drive a pair of fairly easy to drive and efficient transmission-line Paragon Regents.  Is it possible that since the Paragons don't need much power to get them going, that the RELs then don't see sufficient current; hence the need to turn the volume way up with the High level input?  Like you, my ears tell me that the xover frequency selector switches are calibrated differently in each sub.  This does affect the perceived output; still.....,  I also think that, while subtle, the lower output sub's sound has slightly less impact and definition.

"Is it possible that since the Paragons don't need much power to get them going, that the RELs then don't see sufficient current; hence the need to turn the volume way up with the High level input?"

I don't know, frogman. Agree in that I don't think that REL would intentionally design a sub that needed to be dialed up so high for the "nominal setting". Not much headroom for different installs... 

Even with the differences in calibration of the settings between my three (two at any given time), I can't turn the hi-level volume adjustment on any of them up beyond the 12 o'clock setting without over-exciting the driver. My happy zone is between 10 and 11 o'clock. Of course, my speakers are the antithesis of "easy to drive and efficient".

Can you load the amp's outputs somehow (with resistors?) to see if the output increases? 

Dave     

I too had issues with running stereo REL Stadium lll's and want to share what I eventually found. I had gotten them setup and running but one was playing a lot louder than the other for the same volume and crossover settings and the bass was altogether different being "rubbery and boomy"  is the best way to describe it. Definitely not as REL trait.

After confirming and reconfirming both subs were hooked up correctly thru the hi level inputs and with identical cabling for both, I concluded that something was wrong with the louder of the two because if I disconnected one of the high level connectors from the amp, it then sounded just like the other one. I pulled out by trusty Fluke DMM meter and measured the input impedance of the high level cables connected to the hi level input. With the louder REL, the measured impedance from GND to one leg was 9.6k ohms and the other was 19k. The other sub measured 65k ohms on both legs!

I removed the louder REL amp and a close inspection revealed nothing amiss, all connections were solid. I removed the other amp for comparison and that too showed nothing amiss but I did notice that the wiring from the balanced input, the hi level input and the balanced single input were different. Since these were different rev amps, I didn't give it much thought.

After giving it some thought, I hooked up the hi level cable to the balanced hi input on the louder REL and repeated the measurements and now got 65k from both legs to GND! Not sure if this was a miswire issue or a rev. change but with one REL hooked up normally thru the hi level input and the louder one hooked up to the hi level balanced input, the output from both was now identical with the same volume/crossover settings and the "rubbery/boomy" sound was gone. 

Ken