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20 year old REL stentor III amp faulty, repair or replace ?

Discopants

Discopants

FTM
Hi folks

I’ve got a 20 year old REL Stentor III which Is making very disturbing noises, it sounds like arcing but I believe it might be a relay. Its not constant and sounds a bit plinky.

I had this issue several months ago and after leaving it off for a week I opened it up to look inside. I could not see any obvious issues, there is some PCB discolouration around a couple of resistors that obviously get a bit toasty. The capacitors appeared Ok but I know 20 years I should be looking to replace the electrolytics anyway.

I really love this subwoofer, its a fast 10inch long throw woofer, super solid cabinetry and the transmission lined port means its -6db at 12 Hz!

I put the sub back together and it was working great again for a few months but yesterday I really turned the system up for an hour or so and then late evening it was ‘arcing’ again so its back to square 1.

What do folks think, is it worth taking to a good tech for repair and recap or should I just get a new amplifier and wire it to the woofer?

its a 300w class AB amp that can peak at 600w.

Would I have any issues if I got a 1000w class D to replace it ? Any suggestions on a replacement amp ?

Happy new year!

Disco
 
The amps were boggo hitachi FET clone designs, there's next to nowt to them and they're an easy fix. Couple of resistors, bridge rectifier and a few output fets should do it.

Or you could replace with a Hypex plate amp?
 
Fix for sure. It may be older than 20 years ?
My storm mk3 starting making horrible noises. Removed amp section. Big Volt driver was OK. Spotted a burnt resistor and bulging main caps. Sent amp to Rel recommended repair centre. Genserve. Sadly now not in business.
Resistor replaced but sat up upon its legs this time. Hot transistor underneath I think. It was a mod, certainly for the Storm. Big caps replaced. Fully tested. That was years ago.
Still in action. Great old sub.
I'm sure there are a few here could sort it out no problem.
Or call Rel. They may have nominated a new repair outfit by now for the old legacy gear. Who will presumably will have access to all the schematics and mod details required ?
 
The lateral FETs are hard to replace these days, but rarely fail. There are some resistors that always seem to cook, a cheap fix.
 
Probably repairable, but you might well be better off by replacing it with a new plate amp as suggested by others. I replaced the amp in my big SVS sub with a 1000 watt digital plate amp from BK Electronics. Quite a bit better than the original. Not sure they still offer this model but other makes are available, as they say.
 
Thanks for the replies guys, I will make enquiries to fix it.

If I got a new plate amp the plate is unlikely to fit the slot of the old one. I was thinking a monoblock might work near or on the old cabinet.
 
Discopants said:
Thanks for the replies guys, I will make enquiries to fix it.

If I got a new plate amp the plate is unlikely to fit the slot of the old one. I was thinking a monoblock might work near or on the old cabinet.
Click to expand...
Dayton makes many variations of subwoofer amp plate so you may end up finding one that would fit or be a tad smaller and you will only need to add a home made adapter plate. The contemporary versions of these amp plates tend to be smaller as they are class D with switch mode power supply, maybe something like this :

https://www.solen.ca/en/products/dayton-audio-spa250dsp-250w-subwoofer-plate-amplifier-dsp
 
Update, took it to a tech and he found that 2 small caps had drifted out of spec which was causing the relay to buzz.

I've had him recap all the electrolytic caps and he's also replaced 2 resistors with longer legged ones so they stand off the pcb a little further as the pcb is scorched under them.

getting it back tomorrow, hope it still sounds good or better. Price for the work is very reasonable.
 
Heads up The on off switches canv wear leading to crackling on power on but the switch is a simple swap out - high in rush versions
 
It's good to find someone who can do decent repairs for reasonable price. Those guys are rare. Don't know why but they are.
 
Sadly he is very near retirement in his 70s now. I kind of wish I just said to him imagine it was yours and you loved it what would you do to service and pimp it so that it's good for 20 more.

I need to listen to it but the main 10000 micro farrad power caps were in spec, high ripple I believe and very likely up for grabs I would offer them free to any of the thread contributors to this point, would prefer to go to someone who would use them or anyone in need. Their replacements were £70 new Kemet. Just pm me.
 
Although these caps are 20 year old and I play my system for let's just say several hours per day. I've only had it the last quartile of its 20 year life. It was an old boys who bought it for home theatre use, he passed and his son had had it some years out of use. He himself had a stadium 3 (which I have also previously owned.
 
This thread has peaked my interest as I have an original Stentor 1 that I bought directly from Mr Lloyd in 1993.
It's on a very low setting and is never turned off. Do you think it needs servicing? - it appears to work as normal.
 
I’ve have my ATC Concept One sub since 2005 and it has never been shut off. It continues to work just fine.
 
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