Anyone here own a Rel Sorm III sub?

@Dabble, thanks for the suggestion about the resistor - I will look into that. Also thanks for confirming (and explaining) the popping behavior.


Is this true that I should not use a wire wound resistor and instead use a metal foil resistor? If this is the case I can source a Vishay
CPF312K000GKB14 (12K ohm, 3w, 2% tolerance). Would this be preferable?
 
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It doesn't have to be a particular brand, but your reference is to a metal foil resistor, which is better still than the metal film I mentioned.

Metal resistors are a little more expensive, tend to be lower tolerance, smaller, more reliable, longer lasting, and are quieter on the signal path than carbon resistors. I read that the thermal noise is the same, and current noise varies with the resistance material. I refitted my R8 with a carbon resistor as I'm not too fussy, but I wouldn't risk a wire wound resistor which will obviously introduce some degree of induction.

As you are fitting R8 as 12k, I presume you haven't changed the transistors from the originals.
 
I have not changed the transistors. Only R8. Not that I am looking for trouble, but I do not think there is currently any other issue with the unit.

Is there a reason to consider changing the transistors?

Current availability of parts seems to be a potential issue to get ahead of.
 
Some commercially repaired units have been returned with the transistors 'upgraded' along with the resistor change from 12k, 2 watts to 15k 3 watts. Some owners think the unit sounds different afterwards, but not better.

In the absence of a good reason to upgrade the transistors, my preference would be to keep the original transistors, and just up-rate the 12k R8 to 3 watts.
 
Yet another REL owner in need of schematics...

Instead of good full-bodied bass, my Storm III started producing hardly audible grunt - on both high- and low-level inputs.

Upon checking, my technician said it was a blown opamp on the input side. Does anyone have any idea of the wiring of the opamp pins? Or where I should look for documentation?

Thanks in advance:

Boris
 
Got info directly from REL today.

This is the repair, remove and replace with

Q4,Q5 - MJE350
Q9,Q10 - MJE340
R8 – 15k ohm 3 watt
R6 – 22k ohm 0805 resistor
Also check R1 (1.2K), R2, R3, R7 and R19 (100ohm), R17 and R18 (4.7K). Sometimes these will drift and cause bias problems in the driver circuit.
While you are in there replace C1 and C2, 6800uf 63V
 
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Also from REL:

Rarely, the output transistors will fail.


Even more rare, the low voltage supply will fail.
Check the low voltage supply +/- 15VDC under load (connected to pre-amp PCB).
Look at pins 1 and 2 at CN2. If these are under voltage, then I would go ahead and rebuild the LVS.
Replace Q13 with MJE 340 and Q14 with MJE 350. Replace D8 and D10 with BZX55C16V 16V regulators (or similar).
replace C14, C16, with 100uf 25V and replace C13, C17 with 100nF
replace R22, R26 with 22K 1W and R30, R31 with 10 ohm chip resistors.
 
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First post and i already have a story. My rel strata 3 did developed the referred symptoms: growing uhmmmm(even without input), intense tumph sound at powering on (more than when i bought it), intense cracking, and lately the performance really went south.
I Google the issue and found this thread.
Starting from the more simple quilty....the on/off buttom. It was hard to dissamble...one thin sharp knife blade on each side of the green button and the mechcaninsm parts literally popped out. They DID CAUSED he crackling. After figuring out how those two litle swibling metal parts and one spring were able to switch two contacts simultaneously i did notice a black gooh on two surfaces...just scratch that out with the sharp knife blade and after 2 hours of trying two put that together (i did desolder if out to handle it better and even Google it to buy a new one) i manage to put it together and no more crackling. At this stage a remember a had a cheap multimeter....enough for detect the extrems: short and open circuit. SURPRISE: the famous R8 mesured near zero ohms (even" in circuit") so i desolder it on a hurry(!) And mesured it out...Zero ohms...open circuit...
How could this poor thing work in this conditions?
After some days of internet indecisions i bought one 12k 5w (square one ? precision) on a local electronics parts store (readily available) just to try and magic: IT WORKED. I bought the sub used and it sounds maybe better than when that old dude sold it to me suspiciously cheap. No more uhmmm (you have to really focous to hear it...mutting the tv and such ). No more loud thumping at powering on/off (once again...less noticeble than when i bought it used). The performance is on point. All this could have ended really bad because when i desoldered the R8 i didn't had any ways to remove the solder and stayed to much time with the Iron tip in contact with the pcb and that made the top side small metal ring that connects to the tracks to come loose. At the time it didn't give it much importance but after soldering the new resistor and checking the trace continuity with my P.R.C multimeter it didn't "connect" with the small capacitor and then i remember that....that metal ring had a function. Solution: used one of the legs of the old resistor to make one small jumper (on the back side). I learn from my mistake....and i know what i did wrong. Note: the R8 was completly open but it wasnt very aestethically afected...it just had partially lost the "shean"/glow/sparkle.
 
I have 3 Storm III's. I run two of them, configured in stereo, on my main system, and love them. I ended up with a spare, so I use that one on my bedroom music / tv system.

One of my main system SIIIs started failing a couple of months ago, with random wooshing sounds. And also occasional whumps when unmuting my preamp.

Upon taking the amp out, it has the typical R8 thermal damage.

Per the excellent, detailed info on this thread, I just rebuilt it myself as follows
- Changed SMD Q9 & Q10 to MJE340
- Changed SMD Q4 & Q5 to MJE350
- Changed R8 (12k, 2 Watt) to 15K, 5 Watt, 5% (I uprated it to 5w per Dabble's comments on 18-Mar-2017)
- Changed R6 (SMD 10k, 1/8 Watt?) to 22K, 1/4 Watt, 1%
- I had a bunch of extra MJE340/350s, so for the heck of it, I replaced Q13 to MJE340 & Q14 to MJE350 too.

Just as a point of interest, I measured R8 after removal, and it was still within spec. But of course I measured it cold, so perhaps it was misbehaving at operating temp. Or perhaps one of the other replaced parts was on it's last legs.

I reconnected the amp to the Storm III, without buttoning up the cabinet, in case of issues, and also to check out the temperature of the new parts.

The good news is that the repair was a success.

However, after letting it come up to temp, with music playing, I noticed that R8, Q5 and Q10 are too hot to touch (for more than a fraction of a second).

Per my Fluke IR gun, the 5W R8 is 160F at it's hottest point. Is that any cause for alarm?

Q5 & Q10 are also too hot to maintain contact. However, I can't get a good angle on the exposed metal surface to measure them with the Fluke.

I assume that these components would get even hotter if it was Summer, and the amp was buttoned up in the unvented cabinet.

 

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Just for comparison, I checked the quiescent temperatures of the hot components:
- R8 is around 120F.
- Q5 & Q10 are warm, but are not too hot to maintain contact (can’t get a good angle for an IR measurement).

I then checked my other main system SIII. This one was serviced 6 years ago by Sumiko, USA. It has the standard replacements, though R8 looks like a 3W AFAICT. The temperatures are pretty much the same. I measured a maximum of 157.5F on R8 with music playing. And Q5 & Q10 are too hot to maintain finger contact.


By the way, a minor correction regarding the change list in my previous reply. It should say:
- Changed R6 (SMD 22k, 1/8 Watt?) to 22K, 1/4 Watt, 5% (should be 1%).

I have a 1% on order, and will replace it later with the correct tolerance part.
 
@tangoextreme, I just noticed your response...

Good to know. R8 was running as hot as 70C in open air.

So yes, as mentioned above, I am concerned that the temps will go even higher with the cabinets buttoned up. Especially in the Summer time with higher ambient temps.

Since my last message, I did some further changes, which have helped significantly:

1) Changed R8 to a 25W TO-220 resistor, and added a heat sink

www.digikey.com/product-detail/en/caddock-electronics-inc/MP925-15.0K-1/MP925-15.0KF-ND/3013536

2) Added heat sinks to Q5 & Q10.

R8 is happy now.

Q5 & Q10 are much better, but still on the hot side. I intend to upsize the heatsinks on these 2 components when I have a chance.

I'm not working on this continuously, so it may be a while longer before I'm done. But I'll report back with pics and final results when I'm finished.