DN2540/LM317 CCS works great!

The CCS works really well… It dropped the voltage to one of the 5691 tube correctly as calculated. However, when I put both 5691 tubes in, one of them had a B+ of 115.8v while the other is 106.8v… a 9v difference between the tubes! Not what i expected from these superbly built tubes. And according to jacmusic.com, these are the best ever 6SL7 variants.

So I measured the cathode resistors just to be sure the voltage drop is correct and that it is not due to the CCS. One tube measured 1.058v and the other measured 1.048v. On the spot as far as I’m concerned! (The cathode resistors are Kiwame 820R and the Rset on the LM317 should be some Dale 1% 1k resistors. But this just shows how accurate the CCS is!) This can only mean that even the 5691 can vary from tube to tube! And the ones I have are matched to 58/60 and 58/68 according to the guy I got them from…

Well… anyways, next would be to put these stuff together with the Sabre32 dac and the Placid power supply.

Dremel Versatip 2000

Got a new toy from Sgtooling.com. This interesting store sells CNC mills and lathes. Quite interested in the mills, but it’s definitely something that will have very low ROI… I will need to justify a purchase by building more projects. 🙂

Anyways, I used the versatip for soldering of a pair of CCS for the red base 5691 tubes that i’m gonna try using in the BCF for my sabre32 DAC implementation. It’s a very nice tool. The sound of the butane flame reminds me of my secondary school chemistry lab days with the bunsen burners. One side of the solder tip has a circular hole for the flame to burn. This causes lots of heat to be released from that area. Best to solder with that hole facing up, else the work piece will become hot.

Heat up time was quite quick. The literature listed a +/- 25 seconds duration. It took around 10 – 15 seconds to heat up at the minimum heat temperature. This setting is enough for soldering. Turning up the gas a little more and the versatip had no issues with desoldering speaker terminal connections. This normally takes a long time to heat up with my electric soldering iron.

The easy on and off feature of the versatip also suited my work style. I had to alternate between laying components and soldering. The ease of using the versatip made it quick for soldering jobs anywhere. Why didn’t I get this earlier…