Building the Audio Note Kit 1 SET amp...

A super cool thing about DIY that I have found most enjoyable is the subtle and not so subtle changes in sound when I change out one part for another. If one wants a bit more "old school" warmth in their system, dont go out and buy a new speaker cable or interconnect, put in an oil cap and Allen Bradley resistor in cathode of your driver tube. One guy I know has a seriously upgraded AN DAC and he loaded the circuit with Allen Bradley resistors. He loves the sound and I got to hear it and yes it is way cool sounding. He took a point of view and went with it and can always undo it later on if the mood strikes. Look under the hood of a Ken Shindo amp or preamp...you will find all sorts of vintage parts. I got lots of ideas after googling Shindo and viewing the innards. To much warmth in your system? Try an Audio Note Tantalum or Vichay Nude Resistor in the driver cathode. I settled on AN Tants on my driver tube. They gave me all of the musicality of the Allen Bradley's with a bit less warmth. Some amps have electrolytic caps in their power supplies. Replace one or two of them with oils and listen to how smooth and liquid your amp will sound. I am currently experimenting with hi quality Wima caps in my power supply. Dont get me started on coupling caps :) Lots of fun to be had with them. Being able to change out parts in a SET amp yields very interesting changes in sound since they have so few parts to begin with and it is very empowering to have so much control and spending so little money. So much of this hobby is very expensive...cost come way down and satisfaction goes way up when one enters the DIY arena.

Rebbi,

Where in the circuit are the caps C1 thru C4? Since the silk screen on the board shows a physically much larger size cap for those four, did they modify the original circuit or simply send you the four mylar caps by mistake. Good luck, you're in the homestretch now!
Ron

Jet, you are so right and I so do that! Let me share with you my most recent find for the power supply of tube amps and preamps. I have used the large computer grade electrolytics and recently tried the oil types from GE & ASC. I like the oil types and have mixed them with Mundorf MLytics when more capacitance is needed.

However, nothing prepared me for the sonic breakthrough that resulted when I placed 100% Clarity TC film caps in my Preamp. Oh my. Go look at Parts Connextion and see the TC 600 series of film power supply caps. With no electrolytics in my preamp and these killer TC caps things really opened up and the life like sound of voice and instrument is SOTA.

They are large and you need room under the hood so some gear won't accommodate them unfortunately. TC caps come in 600vdc values with up to 500uf of capacitance. They simply sound spectacular. Since my preamp is tube voltage regulated, and I cannot overstate the importance of tube regulation done right, I was not sure how much these TC film caps would help over the computer grade electrolytics. The bottom line is they are really a sonic joy.

These are the sorts of improvements only DIY initiatives and curiosity will uncover. Since starting my DIY journey I am happy to say the sonic gains in my system are unprecedented and I have learned so much.

Lots of great gear out there designed by brilliant folks and companies. They can often times be brought to the next level with DIY initiative and passion.

Ronnjay, here is a Kit 1 schematic which I believe corresponds pretty closely if not exactly to the configuration supplied to Rebbi. (See page 3 of the pdf for a clear presentation of the schematic, although you will have to refer to the first two pages for the reference designations of the components). As you will see, C1 through C4 provide noise filtering and decoupling for the B+ that is supplied to the small signal stages.

Consistent with Rebbi's explanation of the reason for the two holes and pads at one end of the capacitors, it appears that some versions of the kit were provided with physically large 0.015 uf capacitors (see Section 7 of the manual), and others (including Rebbi's) with smaller capacitors which are 4700 pf according to the schematic. Both values seem to me to be within reason, with the choice depending on the range of frequencies that are considered to be most likely in need of being filtered.

Rebbi & Mapman, thanks for the nice comments.

Best regards,
-- Al

Almarg,
Right. If you go to the product page of the Kit 1 8th anniversary edition (not the C-Core 10th anniversary edition) and you click the download manual tab at the bottom of the page, you'll find photos in the manual of the populated driver board, using the older style, much larger caps. They would have used the top and bottom holes. The smaller sized caps being delivered with the kit these days for C1-C4 use the middle and upper holes, as Al pointed out.

On another note, Brian and I did more testing last night via Skype and confirmed that there are some very wonky AC voltage values on my driver board, so something is wrong there. That seems to be the source of the sonic problems I've heard! It's not impossible that I have some bad solder joints connecting the valve bases to the PCB, so I'm going to go through those and see if adding solder fixes the problem. But in the meantime, Brian is having Digital Pete, his builder in Florida, send me a finished driver board to replace mine in case I can't get mine sorted. I think the one he's sending has the standard Mundorf Supreme caps, but if the board fixes the problem, I'll replace them with my Silver/Gold/Oil caps.

Again, AN Kits customer service has been above and beyond. Although I'll have to swallow some pride to use Digital Pete's driver board in place of my own if I can't get mine sorted, it'll be a quick way of getting the amp in order!