REL Strata III repair issue

My REL Strata III bit the dust. It started to blow fuses so I sent it to REL in CA for repair. To my surprise, I was informed that one of the amp's boards has suffered trace damage and cannot be repaired. They found a complete replacement amp module and are offering it to me for $500. Seems excessive to me. My question to you guys is whether there might be an alternative replacement amp for this subwoofer, or whether it might be possible to have someone else repair the damaged amp.

Thanks in advance.
Thats a bit of a tough call. To get something even close or similar in a plate version you might be looking at around $500. Then by the looks of them the strata amps there oblong and one I had in mind is square. Im not saying it couldn’t be done but not without some modifications to the box. And I would want them to be done right. If you cant perform mods yourself $$$ to have someone else do them. I can check into another thought and report back. I recall the same company having other options/dimentions/ sig. prepossessing but its a little vague to me at the moment.

Another option would be a rack mountable class D separate like those made by Anthony Gallo. The biggest altercation you would need to do is re route the input from speaker terminals on out to the amp. You might find a used Gallo Reference in and around $500. More often then not they go a little higher. And depending which model higher still.

Another option I like would be using a bridgeable A/B amp thats up to the task and running a good quality DSP ahead of it.

Figure out what you would be willing to spend and start from there.

As I was saying its a bit of a touch call if there isnt a GOOD quality new one that will right bolt up, or even come close. Also factoring in that the REL amp failed in one area once, doesnt mean it will fail again somewhere else but theres the possibility, research those specific amps to gain a little more perspective. Will they warranty on the whole amp after work is performed? How much and how much coverage is relevant question. All things to consider. Repair sounds a little costlier than its worth but it still may be the least expensive and easiest/ convenient option for you.

I forgot to add having someone out of house perform the work and weather its worth it is another good question. How reliable are they and some of those guys arent exactly working for wooden nickels but you may save some along the way.  Then you may need to source the new parts and I would want at least comparable stuff. They might offer you a warranty on good faith and keep it, my guy is usually pretty good that way and he sources his own parts. It can pay off to find a good trusted technician and hang on to them.
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I was right they have a couple that might be more accommodating but to be sure dimensions of the REL’s plate are needed. Including plunge depth inside of the RELs cavity to make sure any potential substitute wont have clearance issues.

These amps with built in programmable processors and usb updates should be up to the task.

Hypex are known for making good quality class D amps for sub and full range applications. $364 and $415 at this parts house, you can check around and maybe do better. Both of those in bridged mode will generate more than enough power to drive the RELs sub.

More things to consider, input signal is balanced. If your preamp does not have a balanced output you would have to get an adapter, and I’m not even sure if thats possible or advisable? Someone that knows about it for certain may chime in to confirm.

Power cord is neutric so if you dont have one you will have to source a pre assembled cord to plug and play or buy a plug separately and mate it to the end of existing wire from the Rel to keep costs down.

You will need a PC or know someone with a PC that can set up the Hypex inboard processor and grab updates.  

All that said it wouldn’t take much getting something like that to fit and well and look professional. By some careful trimming if too big. If too small by adding some mitred hardwood trim to the RELs cavity perimeter. Dado cut to bring nearer to flush with the rels outer surface area. Adding a contour would also be nice further enhancing the look. And of course matching stain. If plunge depth restricts mounting at all you could make adjustments for that too in the process. It almost makes me wish I had a broken Rel Strata to work on.

Ask Bill Legall what to do. Cheers,
I would certainly keep everything original 'REL'.  This is an excellent sub and $500 is not much money to invest into your listening experience.

The newer REL products are junk-sourced to china.  The older models were designed/built in the U.K.
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I found this great thread.  The Storm and Strata III are supposed to be very similar circuits with the minor difference of additional capacitance.

an update? boodledude offers sound advice.
Hi frogman,

I read recently about internal vibrations causing stress fractures of PCB traces in subwoofers. The way that REL attached the power supply board at a 90 degree angle supported on only one side, leaving the heavy assembly unsupported on the other makes this a viable diagnosis.

Back in my PCBA days, engineers often used what was called "blue wires" to bypass faulty PCB traces in prototype and early production PCBs, making it possible to complete design verification or to simply consume existing inventory to support customer demand while the PCB manufacturer corrected the issue in future lots.

It boils down to soldering small gauge wire from component leg to component leg thus bypassing the faulty trace internal to the PCB. This should be relatively easy on the REL’s power PCB due to the circuitry simplicity of the PCB, the widespread use of pin-though-hole vs SMT components, and the fact that the PCB is single sided with access lands at the ends of most traces.

A good electronics technician with adequate soldering skills and a schematic should be able to identify the problem traces/solder joints and apply blue wires where necessary.


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.

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? 

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. 

Fantastic information, Ken.  Your description of the sound quality of the suspicious sub is exactly what I hear: "rubbery/boomy"; BUT, from the less loud sub.  I will take a look at the wiring and see if I can find some inconsistency in the wiring.  I'll report back.