Another one bites the dust

A couple of years ago I decided to invest in a decent portable amplifier. Not too big, not too heavy. The main requirement: it has to be a vale amp, with a good manufacturer’s support, relatively easy to repair.  My brother, who was the happy owner of a couple of amps by a certain maker, suggested the latest automatic model. The amp arrived promptly and after a couple of months on air, I decided to buy one more unit, to serve as a spare.

The spare unit arrived promptly as well, but unfortunately with a dead FU-728. It blew the fuse upon the first power up which was kind of unexpected.

Luckily I had a spare FU-728. I did notify the maker, but never heard back.

I cut my losses and decided to buy four more FU-728 from China. These tubes have not been manufactured for at least 15 years so FU-728 available online from Chinese sellers are NOS – new old stock, sitting in storage for at least a decade an half. My suspicion is that they were probably out of spec tubes even when they were new. Of course, you don’t just whack an old tube in an amp without ‘cooking it’ (many recipes available online!) so I carefully followed the recommended procedure.

A few days later, out of four, three were proven to be good. I was happy with that; after all, the price was reasonable. Two years later, one of the three is still as good as new, but the second one died after a year, and the third just last week. The estimate life time: around 500 hours.

Now, here is a bit that puzzles me: why a reputable amplifier supplier would risk their  reputation by anchoring the project on a NOS Chinese tube?

And it looks like that was the very same question that puzzled DX Engineering in USA who decided to something about it: to contact Penta Labs in California with the request for a production of a US made batch of FU-728.

I have to say that I’d only heard of Penta Labs this morning. Penta Labs has been in  business making tubes for over 70 years and is regarded as a world leading tube manufacturer. It is a serious business – so serious that in 1971 it was acquired by Raytheon Corporation, a major US Defence contractor.

Penta FU-728 is not cheap. Advertised at AUD $2,400 plus shipping and delivery (USD$1,599), it costs more than four Chinese tubes. Yet I am seriously tempted.  Without a decent, reliable tube, my amps are useless.

What would you do? Buy a Chinese or a Penta? Or, is there a third option? As always, your input is very welcome, especially if you have a Penta tube in your amplifier.