Contessa ca 15 mini bass

cryan · #1 02-24-2008, 01:17 AM

15 inch speaker two 6v6 two 7025 says it is made by Hohner but can't find any info. Just bought this amp in Tucson at a thrift store and it seems to be working OK. Thanks Cliff

Catanova · #2 09-21-2012, 09:58 PM

I know I am responding to an very old post, so maybe this is a waste of time...but now its 2012, maybe someone has some insight on these now.

I have the same amp and it has been my main bass practice amp for 5 years or so. I love the tube tone especially when cranked and it IS loud. I have used it live a few times but its only useful for a small setting, unless you mic it.

These were built by Bartell of California. Useful web refs are few about this amp, but you can learn a bit about the builder. I do know that they were branded for Hohner and Natural as well. Mine has no brand mark. There were virtually identical guitar versions made as well. I spotted one in Longmont earlier this year, but did not have the foresight to buy it, as mine was working ok.

I have used this amp in my experiments of learning how to repair tube amp circuits, as it needed some work shortly after I got it and now have done various small repairs on it. But last month the 6ca4 rectifier tube died, and all my troubleshooting afterwards was unsuccessful. I took it in for professional repair today and will post a followup if I can justify the repair cost. IMO these amps were probably unappreciated in their day, given the competition they were up against. Dont know how many were built, but I would guess a lot of them are in the graveyard now...

The EH Man · #3 11-21-2012, 08:43 AM

Some of those amps were made by Hohner, post-Bartell. All the Bartell-made units I've seen had 12" speakers.

Catanova · #4 01-07-2013, 10:19 PM

Well, my Contessa is finally working again.

Turns out that one of the 6v6 tubes had a shorted cathode. Because of the circuit design, a shorted power tube will cause the one side of the rectifier (6ca4) to short out due to the current draw. Was pretty sure there was a bad transformer and I thought I had tested ALL the tubes properly during my own diagnosis, but I didn't catch the bad 6v6.

Thankfully the problem didn't ruin anything else in the amp. But since I did a full cap job on it prior to taking it in to a pro, this amp now SHOULD be reliable for the long term, and it sounds great once again!