Laney Cub 12R Hot Transformer Solution

Laney Cub 12R Hot Transformer Solution

VLUU L200 / Samsung L200

I had some doubts about this little combo since I discovered the cab is made of compressed cardboard or some shit which was a shocker (read about it here). But I love the tones I’m getting out of it so I’m hanging in to improve the quality as much as I can. So after recovering the cab with snakeskin Tolex, I added external voltage test points and drilled a hole directly above the bias trim pot so I can bias without pulling the chassis (I use a bias probe to read current). I made a wooden trim pot adjustment tool for it which works perfectly. It was at that time I noticed how hot the thing was getting. I read about the transformer heat issue some dudes were having but this was worse. The entire chassis was too hot to touch. I now have it running at 298 volts on the plates and biased at 22.3 mA which is pretty moderate which left just the transformers as the heat source. I checked the temp on one of them and it was running at 104+ degrees F. The other one I just put my hand next to it and it was cookin too. After a little thought I had an idea. First I took some computer RAM heatsinks and used Arctic Alumina Thermal Adhesive and attached them to both transformers. I had some older Pentium processor 12v cooling fans with 1-5/8″ dia blades which turned out to be the perfect size. They were a bit noisy so I ordered a couple of Noiseblocker NB-BlackSilentFan XM1 40mm x 10mm Ultra Silent Fans. I attached one to each side of the rear cover and positioned them so each was pointed directly at a transformer. Added fan grills and wired them in parallel and made a switch box with a 12v power jack and hooked it all up. A 12v wall wart plugs into the switch box to complete the setup. These little fans move a lot of air and they’re totally silent. So does it work? You bet your ass it does. The transformers are running at 95 F and the chassis stays cool enough to touch it. That’s a hell of a reduction. It creates a flow that runs across the heat sinks, then exhausts out the unused 1/4″ jacks on the back side. The way the fans are situated some of the air deflects off the transformers and flows around the tubes to cool them down a bit as well. All in all the design just freakin’ works, on this amp at least. The only thing I’m still unsure of is just how hot are these transformers supposed to get normally. and am I just treating a symptom of a bigger problem. I’m still looking for that answer and I know it’s out there somewhere. But at least now I don’t have to worry about cooking a transformer or any nearby components,

VLUU L200 / Samsung L200

How hot do your transformers get? Leave an answer in the comments below. Click here to find out what these are made of!

UPDATE#2: Be sure to check out the final and definitive update to this post and more about the fans here.

 

 

Russ

Dean Leslie West Peace Sign Signature Soltero, Dean Leslie West Flame Maple Tobacco Burst Signature Soltero, Gibson Les Paul Studio, Hamer Studio,, Epiphone Les Paul (Korean), Ovation Celebrity, Laney Cub 12R, Blackstar, HT-1R, Jet City JCA20H, Jet City JCA22H, Orange OR15, and a lot of dirt pedals, some store bought some DIY.

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