Cornet Photo - kit in progress

Grover · « **on:** 14 Mar 2004, 11:18 pm »

The Cornet is probably only about 70% at this point, but the board is almost complete. Just waiting for some Nichicon 10,000 uF caps to come in. I've been playing with my digital camera today and also poking around Audio Circle learning the ropes here. I can't quite figure out how to get the photo to appear automatically in the post, so I've included the URL below of my Cornet board.

I went with components that fit pretty well in their designated spots without needing to shoehorn them in. But most stuff is upgraded over stock. Riken Ohm resistors in the signal path and Kiwame elsewhere. Mostly Sonicap capacitors, with Auricaps at C5 and Angela film and tin foil at C1 and C3. It's being a fun and challenging project. I'll post more photos as I finish up the PCB and start assembling the chassis parts.

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=261

Marbles · « **Reply #1 on:** 15 Mar 2004, 12:25 am »

What you do is go to the gallaries section and click on the picture, then your right click on the picture and go to "Properties"

Then copy the URL of the picture.

Then you come back to this posting section and hit the "IMG" button ,

Then you paste the URL, and hit the "close Tags button"

It looks VERY good so far. I hope you like yours as much as I like mine.

Frank McCrea · « **Reply #2 on:** 15 Mar 2004, 12:56 am »

Hi Grover,

Very nice looking.

Be sure to keep the photo's coming.

I too am about about 70% finished on my Cornet project, been waiting for a chassis from IAG so I've been at other things.

Actually I've been waiting since the middle of last Nov, I guess you could say I'm getting a little pissed with the (next week, yeah next week) replys I've been getting from IAG Audio.

Serenity now baby!!

Look forward to seeing your finished Cornet.

Frank

some young guy · « **Reply #3 on:** 15 Mar 2004, 01:48 am »

nice grover! what are you using for an encloser? what tubes will you be using?

Grover · « **Reply #4 on:** 15 Mar 2004, 02:27 am »

Marbles - thanks so much for the tips on posting photos. I thought I tried exactly what you said, but a preview of my post showed only the "dreaded Red X".

I'll keep trying.

I purchased the standard Hammond aluminum case for the Cornet. I've never done any metal work before, so it's been interesting. My biggest oops so far was while using a professional Milwaukee half inch drill that I borrowed from work. Trying to cut the half inch holes for transformer wires, I forgot to clamp the chassis to the work bench. What a surprise I got! Once the chassis stopped spinning around the drill bit, I had a raggedy hole "somewhat" larger than half an inch. Rubber grommets will hide a multitude of sins, I hope.

I've got a bunch of tubes to play with. GE 5-Star 6087, Bendix Redbank 6106, Brimar GZ32 for rectifiers. Both my amp and pre use the 12A?7 type tubes, so I've collected a number of old stock 5963, 12AU7 and 12AX7 types. I have some RCA 7025 labeled Beckman that might be cool. It will be fun testing out the Cornet and I'm sure it will force an upgrade to my cartridge which is an older Grado.

GRD · « **Reply #5 on:** 15 Mar 2004, 10:09 pm »

Very nice work. I'm amazed at how you were able to keep the layout so clean, especially when fitting the Riken's. Looks well thought-out. I will be interested in your listening impressions with the various tube combinations once the unit has a chance to burn in awhile. I'm quite partial to the 6106 and 6087 rectifiers.

SHIF · « **Reply #6 on:** 17 Mar 2004, 06:13 am »

Greetings Grover,
Very nice assembly of the components, especially those Auricaps. I know how difficult it is to work with those finely stranded lead wires.

I wish to suggest that you remount the ceramic power resistors however and provide at least 3mm of space below them. Use a couple Starbucks stir sticks for temporary spacers while soldering.

Using a Fluke infrared temperature probe with my DMM I measure R21 to be over 220 degrees F. This will eventually scorch your PCB. R22 is 165 degrees.
My R18 gets quite hot too, 155, but that's not an issue for you.

-SHIF

GRD · « **Reply #7 on:** 18 Mar 2004, 12:42 am »

SHIF,

Thanks for the heads-up. Is it standard procedure to mount these types of resistors with a small air gap to protect the board? Their design (ceramic capsule) seems to indicate they are rated for high temperature operation. Never thought about the board contact. However, I've never noticed any scorching during the many times I've swapped components and I've never encountered the telltale odor of overheating. Perhaps the board material is rated for these temperatures.

Regards,

GRD

SHIF · « **Reply #8 on:** 18 Mar 2004, 03:05 am »

GRD,

I don’t think there is a serious issue with the temp of these parts and board contact. I know these can handle up to 200 degrees C and mine top out at 107. It just seems like having some space beneath these hot blocks makes sense. The Xicon product description states “ self-extinguishing”, how does that make you feel?

My configuration mounts everything on the back side of the board with the valves, so I’m watching the temps on the nearby caps with more attention. Then again my resistors can radiate heat easily straight up where as a conventional Cornet configuration has the components on the roof of the enclosure, inside.

On another topic, for component upgrades I’ve only installed Auricaps for C5 and C6. I’m interested to know if using Rikens in the signal path is the next logical upgrade.

I’m happy to report very musical results with this project so far. I don’t have my enclosure fabricated yet but I’m gaining many hours of enjoyment listening to my Cornet which is simply mounted on a 1x6 plank.

-Shif

Grover · « **Reply #9 on:** 18 Mar 2004, 06:13 am »

SHIF -

Thanks for the suggestion on the Xicon power resistors. I wish I had thought of that myself before I trimmed the leads. I'll probably do what you suggest, but I'll have to fashion some extensions unless I can bend the leads differently to make them longer.

The Kiwame resistors in my Cornet that are in-line with the Riken Ohms are all mounted about 2mm above the circuit board. This wasn't for heat dissipation, but simply for looks. The Kiwames sort of disappeared when I had them right up against the board. Lifting them up was better.

GRD · « **Reply #10 on:** 18 Mar 2004, 04:53 pm »

SHIF,

I've changed C5, C6 (twice), C7 and C8 along with adding Rikens in the signal path. Each change was subtle. And I think additive.

I changed C8 and added the Rikens at the same time. With this change, voices became more natural sounding. So, I can't say it was the Rikens or the C8 or both. But it was a worthwhile improvement to me. The C8 was relatively cheap.

I also noticed more obvious differences in the sound of different tubes after I completed the upgrades. In my original version (Auricaps in C5 and C6), tube differences were less apparent. Now it is very easy to hear differences in tubes. I note this becouse it was a suprise to me. Of course, the downside is that I now have a whole box of rectifiers, AX and AU tubes I picked up at various swap meets.

GRD

Mikey · « **Reply #11 on:** 19 Mar 2004, 02:53 pm »

Grover,

Where did you get the Kiwame resistors, and how much $$$ are they?
Does you supplier have a large selection of values?

Thanks in advance,

Mikey

Grover · « **Reply #12 on:** 19 Mar 2004, 03:28 pm »

Mikey -

There are two suppliers of Kiwame resistors on the web that I am aware of. Michael Percy Audio, where I got mine, sells for $1.10 each in the 2 watt size. diyhifisupply.com sells for $1.00 each. Both dealers are well stocked. I got the Riken Ohm from Partsconnexion.com at $3.20 each. I haven't yet added up all the parts costs of my Cornet. I'm guessing it will come in just over $500 including the price of the kit itself. That includes almost $90 that I spent on a custom wound ElectraPrint transformer instead of the specified one from Hammond.