[Speedskater]

What is the dimension of the gap between the 'hot' and 'neutral' traces at 'C3'  ?
And between the "hot" trace and the mounting holes?

[BradJudy]

What is the dimension of the gap between the 'hot' and 'neutral' traces at 'C3'  ?
And between the "hot" trace and the mounting holes?

0.15" and 0.175" respectively.  The distance between H and the mount can be adjusted by angling it in a bit more, but I'm stuck with the C3 one unless I make the traces thinner. 

One could also use nylon screws for mounting and not worry about the corners. 

Any idea what a minimum distance for AC leads traces should be?

[kyrill]

hoi when are they ready?

I need them fast

[BradJudy]

hoi when are they ready?

I need them fast

To ensure they are right, I would likely order just two or three at first, along with the various supported parts.  Once I verified that everything fit right and no revisions were needed, I would then place a larger order.  I don't know how long all of that would take.

I'm hoping the community participation will help reduce any errors before the first run.

I think removing the ground trace might be a good move for the next revision, otherwise it's looking pretty good. 

I'll take a look at the fuse mount option, but the more I think about it, the more I think it should be done off-board with the user's choice of implementation.

[Speedskater]

Any idea what a minimum distance for AC leads traces should be?
3 mm or 0.12 inch rings a bell, but I don't remember what voltage they were using.
Maybe you could straighten the trace and add a small round pad for C3 and C4.
More clearance would be good, especially for anyone with a large isolation transformer.
Large isolation transformers have a nasty voltage kickback when a primary fuse blows and the field collapses with nowhere to go. 

[Martyn]

I looked at the Hammond 1455 extruded cases and this doesn't work well for sizing to fit.  In order to get one with the height clearance for the CMC (1.3" for the CoilCraft, 1.65" for the larger JW 8100), you'd have to go to a size that's at least 4" wide.  Even with the ground trace the board is only 2.4" wide. 

Why not make the board double width so that it can take two Felixes side by side? That way users can filter their SB and amp, or pre-amp and amp, or DAC and amp, or CD player and amp, or whatever pair they choose. I would imagine that a single ground trace would be OK for two circuits (or no trace at all as has been suggested already). I'd guess that this would then fit either the 4.06" or 4.92" wide Hammond box, both of which are a touch over 2' high. This might also be slightly cheaper than buying two "single circuit" boards, and folks who want just one circuit can always trim the board to the width they want (crude, but effective).

Martyn

[randytsuch]

My vote would be to get rid of the ground trace.  Then, you could make the board a little thinner, and still have room to move the hot line away from the screw hole a little, to give more clearance between the screw head and hot.  Yeah, you can use nylon screws, but it would be nice to be able to use any screws.

Otherwise, I would go with what you have.  Everybody will have different uses, and different requirements, so you can't make a one size fits all.  So, go with this, it is simple enough so it can be easily adapted to most situations.  If you add stuff, or make a double one, gets more complicated, and not as many people will be able to use it.  Keep it simple.

BTW, what size screws did you make the holes for?

Randy

[poseidonsvoice]

Brad,

Count me in for about 5 of these PCB's. I figure you are going to try to set up a group buy. Thanks for all your effort.

Best,
Anand.

[BradJudy]

Okay, no ground trace, a bit more spacing between the corners and leads.  I just adjusted the corner screw holes to be 0.15", which should accommodate up to #6 machine screws.  The board is 5"x2" at the moment.

I also "unlocked" the traces from the C3/C4 holes to off-set them and expand the gap between the traces to 0.25". 



The number of boards ordered has a big impact on the per-board costs, so once we seem settled (I think I just need to triple-check measurements), then I'll start another thread for a group-buy.  I'm hoping for only one prototype round with something this simple since it should only be a matter of proper spacing.  The prototype rounds for PCBs are the money sinks as each is disproportionately expensive compared to the quantity purchase.

[randytsuch]

Okay, no ground trace, a bit more spacing between the corners and leads.  I just adjusted the corner screw holes to be 0.15", which should accommodate up to #6 machine screws.  The board is 5"x2" at the moment.

I also "unlocked" the traces from the C3/C4 holes to off-set them and expand the gap between the traces to 0.25". 



The number of boards ordered has a big impact on the per-board costs, so once we seem settled (I think I just need to triple-check measurements), then I'll start another thread for a group-buy.  I'm hoping for only one prototype round with something this simple since it should only be a matter of proper spacing.  The prototype rounds for PCBs are the money sinks as each is disproportionately expensive compared to the quantity purchase.

Looks good.

If you can send me a 1:1 scale, I'll double check it for you.  I have most of the parts, so I can check to real parts.  Only have the miller chokes, and some values of the caps, but I can get the datasheets for the other stuff.

Also, if you were not planning to, you should amortize the prototype costs into the group buy.  Let the group buy pay for all the costs for the PWB.

Randy

[Gordy]

If you can send me a 1:1 scale, I'll double check it for you.  I have most of the parts, so I can check...

I've examples of all the coilcrafts, though the spacing is identical on all three, and can check those for you.

[BradJudy]

Thanks for the offers, but I expect that placing parts against an image won't be as accurate as comparing the parts spec sheets to the board specs (each being noted down to 1/1000").  Getting a precisely formatted image would be much harder given this software.  If anyone is interested in installing ExpressPCB and checking the measurements, I'd be happy to post the file. 

I'll check the measurements tonight or this weekend and then place a prototype order, along with an order for the fitted parts. 

[Hap]

Excellent work people!

Can any of you clarify the best way to configure the caps in the line.

The original Felix schematics has the large value caps in the C1 & C4 position; which would place the C4 cap close to the CMC on the output side with the bypass caps in the C2/C5 and C3/C6 locations.
Many have suggested placing the .01uf caps bypass caps close to the CMC, and the current board project offered by BradJudy looks like the caps would be configured that way.

Would the cap configuration affect the sound in any way, or is there some other reason for keeping the small value bypass caps close to the CMC.

Cheers

[JoshK]

You want to put the bypass caps closest to the CMC.  I'm sure the original schematic you reference was drawn that way for convenience only.

[BradJudy]

My use of component numbering does match with the page 1 schematic - sorry for any confusion.  On the board the caps will only fit if the large value ones are on the outside and smaller values on the inside.  This seems to be the recommended configuration.

[Occam]

Hap - Good Catch! 

I'll fix the Schematic on pg.1 of this thread, to indicate the smaller values should be closest to the CMC.

[TomS]

... the smaller values should be closest to the CMC.

Just curious what reasoning is for this, as it is a bypass?  Lead inductance?  I usually piggy back those to the big caps anyway (when there is no PCB) so the leads can get a little long.  Tom

[JoshK]

The bypass caps are for the highest frequencies, therefore it is as you say in that you want to minimize lead inductance and other stray inductances. 

[tanchiro58]

Excellent work people!

Can any of you clarify the best way to configure the caps in the line.

The original Felix schematics has the large value caps in the C1 & C4 position; which would place the C4 cap close to the CMC on the output side with the bypass caps in the C2/C5 and C3/C6 locations.
Many have suggested placing the .01uf caps bypass caps close to the CMC, and the current board project offered by BradJudy looks like the caps would be configured that way.

Would the cap configuration affect the sound in any way, or is there some other reason for keeping the small value bypass caps close to the CMC.

Cheers

Does this configuration change the sound since I built the Felix based on Gary's schematic? 

http://www.audiocircle.com/index.php?topic=50284.20

[Hap]

tanchiro58,

Also questioned the others about whether this configuration changes the sound since I built the my first Felix based on the original schematic too...

The first Felix I built used the Miller CMC and .47/.1/.01 caps; I built it exactly as the original schematic, placing the output .47uf cap next to the CMC, and the .01 bypass cap farthest away.
I put this one in the AC line to my preamp and was very happy with the results.

After seeing the other builds which placed the smallest value caps next to the CMC, I built another Felix this way using the same parts, and hooked this one up to my preamp.

My results are subjective; but I seem to notice a little more detail and speed to the sound with the .01 bypass caps close to the CMC; at least in my audio system.

I did not notice much difference with the different Felix config when they are used for my small TV monitor.

Cheers.