F5 pcb group buy...

[mstr]

F5 boards

Hello Peter,

time for another buy! Are you still on stock with the F5 boards?

Please send me 3x F5 boards (6 channels).

I've just made the PayPal transfer for the boards, if there are any problems, please let me know.

Thanks for your effort,

Michael

 

[Peter Daniel]

Thanks for the order, it will ship today.

At the moment, I have approx 15 stereo sets left; when they gone, it may be a while before I reorder.

 

[1MOR]

Peter, the boards arrived. Thank you!

 

[Peter Daniel]

at first I had connected both yellow wires to the gnd of last filter cap
http://www.diyaudio.com/forums/showthread.php?postid=1807410#post1807410
but after Andrew T recommendation - one post ubove I did extension with gray wire
one last thing - I don't have safety network - I only experiment at that point

That grey wire extention is not a good idea. Both ground wires should be connected directly to the caps.

Are you using a single supply to power both amp channels?

 

[samoloko]

Hi Peter

at the moment I am trying to find the reason why I get buzz so I use only one F5 amp pcb which Is connected like on the picture
0V from the PSU filter caps - gnd of F5 amp pcb - yellow wire
0V from the PSU filter caps - speaker return - yellow wire
the Input of F5 amp Is open circuit

 

[Peter Daniel]

The input shouldn't be left open if you are checking for buzz.; you shoulkd have a properly operating source connected.

There is not much that can go wrong here, I've built many amps wired this way and all worked fine.

See pics of my latest one: http://www.diyaudio.com/forums/showthread.php?postid=1740824#post1740824

Just make sure that both ground wires are connected DIRECTLY to the commonn point on caps, without the extender. Ground from RCA connect directly to SG point on amp board and nowhere else. RCA should be isolated form a chassis.

 

[samoloko]

thx Peter

I connected to cd player
yes there were no ground loop buzz what I got when open loop, but instead of I got too much hiss when pause

 

[Peter Daniel]

Hoe is it when you put it into stop?

 

[samoloko]

no difference
but I have connected directly to dvd output without pot (not cd as I post) with 5 m long cable
I don't understand why I got buzz when Input Is not connected
sure my commercial amp don't do that

 

[Peter Daniel]

How is it when you switch the power off from the DVD?

All your wires are pretty long and not arranged optimally, that might be a reason for a buzz.

 

[samoloko]

when switch off - I got big thump and no hiss at all

 

[Jozua]

Any F5 boards left

Peter

Please let me know - I am interested in a stereo pair.

Thanks

Jozua

 

[Peter Daniel]

Yes, still available. Ordering info can be found in a first post of this thread.

 

[samoloko]

thx Peter for the great help
you're the man

 

[Jozua]

F5 Boards ordered

Peter

I have just done a Paypal payment.

If I cannot source good parts locally I might approach you to quote for parts as well.

I am looking forward to see how the F5 compares to my DIY Aleph 30?

Regards

Jozua

 

[Jozua]

Any parts preference

Gentlemen

Are there any recommendations re which brand of resistors (Mills, Dale, Riken etc,) works best with this board. It is so small one could just as well go over the top?


Regards

Jozua

 

[Peter Daniel]

When it comes to standard resistors, I recommend Dale CMFxxxKQFCT available from DigiKey. If you want something better (which may not make much difference anyway) you can go with Caddocks MK132 or Vishay S102.

As to power resistors, blue 3W Panasonics fit the board, but I'd reather go with Mills 5W (available from percyaudio or partsconnexion)

 

[rickmcinnis]

MK132 on the heatsink

On the amp most recently presented (post 2800) there is an MK132 mounted next to the output device.

As you know, and expect, I cannot figure out which resistor this is and why it is there.

Would you mind telling me?

AS ALWAYS, thanks very much,

 

[Peter Daniel]

Those were actually MP-930 used as series resistors between filter caps. Didn't work out as expected and I switched to Mills mounted directly on the caps.

An externally hosted image should be here but it was not working when we last tested it.

 

[Peter Daniel]

Luke S., you tried to contact me yesterday, but my email reply bounced back.