rebel 20... 8 ohm tap cuts out

[joitheboat]

Ive had the rebel 20 for awhile and love it. Ive always used the 16ohm tap, but I got a new weber 410 cab last night. It has a 16ohm load in that only uses 1 pairof the speakers. .. Works fine on that. It also has an 8 ohm in that uses all for speakers. When I connect the 8 ohm load to the 8 ohm tap, the amp cuts or soon after starting to play.

Any ideas? Ive opened up the cab and used my multimeter to ensure that the 8 ohm input is really an8 ohm load (2 8ohms in series connected in parallel to the other identical series pair.

Thanks!

 

[thickwood]

Clean all your speaker out jacks with small brush and D5 Deoxit spray , it will cut out on load with a marginal connection if its not clean enough !
I assume your {not} using a instrument cord for a speaker cable !
All high power connections that have a weak connection will begin to cut out , cold solder joints also.
I have a R20 also,2 yrs no problems except a tube or 2 !
I redplated a couple also in the R30 amp,i ask for high Ip, tubes that have a higher draw and less quickly breakup.

Bruce has a high plate current transformer and its open up the power on these Rebels.
Good luck , at least spray a plug and run it in and out a few times.

 

[joitheboat]

Thanks. The cab is nearly brand new. All jacks were clean. I did move one speaker wire from a painted terminal to a bare metal one and will check the output jack on the egnator tonight. My speacker cable is good- made it myself from doubled up heavy gauge wire.

I will try again tonight before practice.

 

[thickwood]

I ran 2 cabinets into my rebel 30 to see if i had any issues but it was flawless.

I used vacume cleaner 120v cord and made my speaker cords with that !
Not all jacks and plugs are exactly the same it seems,i used switchcraft plugs for mine and they snap in snug.
Hope you get it right !

 

[joitheboat]

Thanks. I too used good switchcraft plugs.

I popped open the amp and double checked all the switching jacks and biased the tubes while I was at it. Each bias point tested maybe 7mv off spec. I returned them to 40 and 45.. or atleast within .5 to .7mv of that... very very sensitive pots.

something I did must have corrected it. 2 hours of high volume practice last night with zero problems.

sounds great too.