F3 Builders Thread

Melon Head

Banned
2006-11-10 10:14 am
Hi everyone.
Well with everyone purchasing their F3 boards through Peter, I felt it made a lot of sense to start up a builders thread, to share the journey together.
To start off, I thought part selection would be a good topic to discuss.

AMP PARTS
For resistors I am thinking of any of the following:
Caddock Mk132,
Vishay Bulk Foils,
Vishay Dale RN55D,
Mills
Its probably important to discuss which resistors are the most critical.
Any other suggestions?

Electrolytic Caps
Well besides Panasonics I am not to sure what would be best at a reasonable price.
I am most concerned about what to use for C1 and C10

Film Caps
Also not to sure about what to use here maybe Wima MKP10 might be a good choice.

POWER SUUPLY PARTS
Electrolytic Caps
Will 30000uF caps be sufficient for this amp?
I can get hold of Epcos SIkorels, but these might be overkill for a Class A amp.

Rectifier Diodes
I have MUR860 diodes, will these be a good choice.

Resistors
Mills or something cheaper possibly.

Any other suggestions would be welcome?

Some pictures would be a nice contribution if anyone has already started assembling theirs.
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
All those parts sound pretty good to me. Probably the most
contentious part is the big electrolytic at the output. If you could
parallel up a pile of Elna silks or polypropylenes to form the output
capacitance I think that would be the biggest improvement you
could make parts-wise.

Yes, I can see it now.... 100 parallel Solen canisters per channel...

:cool:
 

Melon Head

Banned
2006-11-10 10:14 am
Thanks Nelson
I forgot about Elna Silmic caps. I just had a look at these and the highest vaue they have at the required voltage is 1000uF, so that means 15 of these suckers.
Maybe Panasonic FC would be a more sensible choice either 5600uF 25V, or 3900uF 35V.
 

Melon Head

Banned
2006-11-10 10:14 am
Having said that, I think most people will want to stick fairly closely to what will fit on the PCB.
So if anyone has other suggestions about what would be good to use here, then that would be most welcomed.
I think Peter likes to use Jenson Capacitors, but I don't think he was completely happy with the result.

The other thing worth discusing might be the choice of values.
The original uses 15000uF, 220uF, 1uF in parrallel.
Maybe their is a better combination of values that will also fit on the board.
 
If I can suggest something for multidriver speakers, is to split the output caps between drivers and use whatever is needed only.

For instance, in my particular setup, I'm using 6.8uF Siemes MKV in tweeter network (1st order filter) and BG N 330/100 with the midrange driver (again first order filter only). No need for other big caps. If you have a woofer, then you can put 10,000uF cap there too, but it could be separated from mid/high output.
 

Melon Head

Banned
2006-11-10 10:14 am
Hi Peter
Thanks for that, I noticed you mentioned it in your ZV9 build.
If I understand correctly you are suggesting placing these caps inside the speakers splitting them across the different drivers.

Just to clear things up the purpose of these are dc blocking capacitors is that right?
If so won't the tweeter be more vulnerable to damage by doing it this way?
I really don't know much about this so if you could explain that would be appreciated.
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
thanh1973 said:
I forgot about Elna Silmic caps. I just had a look at these and the highest vaue they have at the required voltage is 1000uF, so that means 15 of these suckers. Maybe Panasonic FC would be a more sensible choice either 5600uF 25V, or 3900uF 35V.

Trust me - people obviously are missing a big bet on the Elnas.

:cool:
 
thanh1973 said:
Can anyone supply a spice model for LU1014D?
thanh, Send me a PM ;)

As far as Rs go, I've been using the Caddock MK132 in critical, low power (signal path mostly) spots. I'm of the opinion that resistor distorion may have a few significant factors effecting it. Some, like the actuall material, film, foil, whatever, may not even be advertised but are significant. An important factor you can deal with is the "thermal memory distortion". That is, when in operation, you don't want the signal to be varying the power disipation greatly. Basically that boils down to selecting a component with high enough power dissapation and actual size but, also very low temp coefficient. Most bulk metal foils are the best at around 5-10ppm. In other words, the resistor value does not change as power, or temperature, varies with signal.
Just my 2 cents :xeye:
 
thanh1973 said:
Just to clear things up the purpose of these are dc blocking capacitors is that right?
If so won't the tweeter be more vulnerable to damage by doing it this way?
Yes, they are for DC blocking. And Peter is still using them in series with the speaker for that purpose. Someone correct me if I'm sounding off the wall or something. The way he is using them he is also combining any cross-over components with the output cap to arrive at one less cap in the system. In addition, since bass signals are not going through the tweeter cap, any possible distortion from the bass should have less effect on tweeter signal.
 
Trust me - people obviously are missing a big bet on the Elnas.

Thank you very much for your recommendation :)

In the capacitor tests of Cyril Bateman non-polar electrolytic capacitors showed much lower distortion compared to normal polar electrolytcs, especially whith higher bias voltages across them, so a non-polar Silmic version might potentially be even better, if only one could get those.

To my surprise, when browsing through the Silmic datasheet I found the following statement: “For bipolar capacitors, consult with us.” So it looks that they would offer bipolars. Not sure though how they will react when I call them up for my 50 units :xeye:
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
thanh1973 said:
Hi Nelson
So are you suggesting 15 x 1000uF Elna SIlmics is definitely worth the effort?
Or can we get away with a lower capacitance eg 5000uF instead of 15000uF.

I haven't tried it, but this being the only capacitor in the signal path,
I think it's worth the effort. The F3 has a very sweet top end, and
anything you can do to improve it is worthwhile.

:cool: