January 20-23, 2001
Bjørn Aaholm
Copenhagen, Denmark

 

Ah, the new year... Just got passed the busy season in December and things went into a slump. The january depression had started. Chatting with Bjørn over ICQ every night gave us the idea that I should drop by Copenhagen again for a visit. I had some time off, so what the heck, it's only a 970km drive. I loaded up my car with my 1H4 preamp and EL34 power amp, just to have some fun while we were there. Nine hours later I was in CH, yeah yeah, there was a blizzard near Hamburg. Luckily it cleared up after an hour and traffic was back to normal.

We unpacked my gear and set it up for a listen. We agreed that the 1H4 preamp was not a serious match for the 26 preamp Bjørn had built. The EL34 was quite a step up from his NAD sand amp though, sorry Bjørn ;)  We discovered the next evening that there was some major distortion in the EL34 amp when listening a bit louder. What the heck... it took a while to figure it out, but I had apparently switched the driver and gain tube at some point. As the EL34 amp had been in the closet ever since I finished my 71A amps I never took another look. We switched them back and found we could now enjoy the system.


The setup during the stay. My 1H4 and EL34 on the foreground.

 

Bjørn's DAC was bugging him for some time now. He didn't like the output tubes, ECC81s... I agreed and we decided to rebuild the DAC to hold 5842s instead. Some minor changes to the pcb were made and we were finished within a few hours. This was a really good improvement in sound, very nice indeed.

BANG....tzzzt... SHIT!!!!! What the @#*&$ !!!   Something sparked and popped, can't be good. A quick look at the DAC showed that the FET that was regulating the B+ had fried itself. How can this be?! A quick look at it's specs told us the original builder was a cheap skate and plugged in some el-cheapo parts instead of the good stuff. The FET in question was running at maximum voltage levels and the dissipation after the 5842 mod was just too high. Dammit! We went into town the next morning and decided to convert the DAC into a passive B+ supply instead of a regulated one. Out went all the sand stuff (ss) and in went some new caps and resistors. Wow, what an improvement!!! Nice!!!


Three AM, DAC blown: we should either get some shut-eye or a pot of coffee.

 

Evening again, we just got back from the Italian restaurant that had seen us come in for the third evening in a row :)))  Hey, it was close by and cheap, what else can a DIY'er ask for ?!  Bellies full and very lazy we sat down. Lights dimmed, tubes lit, music playing, glass of whiskey... ahhhh.... Al our work during the (extended) weekend had paid off.

 


Bjørn's surfing position