Wednesday, July 14, 2010

5687.. status

After few hours of ‘burning in’ this is what I found.

The microphony of the tube is very tube dependent! I have bought two sets of the 5687 tubes by Tungsol and so far have experienced less ‘microphony’ in one than the other one!

Somehow AC heaters induces more hum, as such DC heating is more favourable.

I have stopped playing with it and waiting for the dual 50uF+50uF which was originally specified to arrived. There is this low AC humming which I suspect coming from the B+ voltage as I have used a substitute caps of 20uF instead of the 50uF originally specified. I was desperate and need to get it running before deciding to get the expensive stuffs or not. The dual cap was bought from ebay and could take anything form 7-14 days to arrive. Item was bought last week..

Till then..

Friday, July 9, 2010


Had the opportunity awhile back to audition the infamous F5, 25W+25W pure Class A power amp in my system. It's DIYed by a fellow forummer. I bought the PCBs.. wonder if I should build one.
Here the pix:

If you're looking for a kickass Class A 'heat' monster, this is it! For Class A purist only. Should be able to satisfy full range lovers. Unfortunately at higher than 'normal' listening levels, my RTL3 is gasping for more 'air'..the 'thirst' that only the Technics that I have can satisfy... 'nuff said.

Wednesday, July 7, 2010

The good news and some 'bad' news..

Okay, the good news is, I have completed the tube preamp, hurrah!!! That was about a a week ago.
It was worth the wait (and the agony of waiting)! The preamp was connected to a discrete 40 watter (nicked name,D'Bomb) and the sound is simply marvellous albeit some issue which is irritating me right now.

One, I have humming issues, then buzzing then 'crackling' issues.. After much googling and reading more about tube amp designs.. I managed to solve the buzzing by opting to use DC heater as opposed to AC heaters. BTW, I have read and done all the do's and don'ts about tube amps building thingy, like wires crossing at 90 degrees etc.
The humming and 'crackling' although very soft and only audible when I am not playing anything, it is just 'psychological annoying'... Since I used some 'alternate' (read cheap and what is avail.) parts to what was being specified in the original design, now that I have heard how good it is and believing that there is a potential for it to become 'better'), I think it's worthwhile to invest in quality/premium parts and I have decided to buy the 'good stuffs' online.. I also found the TUNGSOL 5687 is kinda 'microphony' and it is known for that! There are other drop in replacement for this 5687 but I would not do it till further listening. Since this is my first tube project, I just want to have some experience and maybe moving on to other popular tubes. More updates later..

The casing used (like a metal pizza box) was bought cheaply from a manufacturer excess stock meant for something else.. hehe

Pic shown the preamp during the 'wet-run'. Speakers used was the Gale 3030 floorstander and I could not believe the amount of good solid bass coming out!