F5 power amplifier

[AndrewT]

is 330watt enough for both channel?( although nelson recommend 200watt per channel)

330VA 18+18Vac has an AC current rating of 9.1Aac.
The maximum continuous DC current this transformer can supply is ~4.6A
if you draw 2.6Adc then it will be running at 57% of maximum continuous capacity. It should be OK, it may get a little warm, so keep it well ventilated.

 

[udailey]

So, Andrew, where do you find these DC output transformers I bet they DO get warm!
Just joking. I know what you meant but had to take the rare opportunity.

 

[chchyong89]

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

i tested with test pen on the signal in channel and the LED light up, is it normal and ready to connect my signal into it?

because i killed my preamp last time when i connect through the F5 board i solder last time. now i am scare to connect any signal into it again before any advance comments.

 

[juma]

...i tested with test pen on the signal and the LED light up, is it ok to connect my signal into it? ...

Is that PCB that you are using for F5 bought on e-bay?
I saw one quite like it and it had errors. Check your PCB - compare it with schematic, it might be bad...

 

[cviller]

Yeah, you should probably direct the questions to the one who sold you the boards.

 

[awc]

Your green wire looks like it goes to + suppy ? dose your green come from ov ?

 

[awc]

"supply" sorry
these boards work fine, (sorry guys I got that board before I came across this site) Ive uploaded a pick of what to do.
DONT CONNECT SPEAKERS UNTILL voltage adjustments are set and then
use some old or cheap speaker make certain no noise coming through.

 

[awc]

I just re read your post. You need to check your soldering underneath as well with your light, you may have "sgn in" touching "-neg" power in.

 

[tinitus]

Looks like the device legs below board could be touching active board lines they shouldnt touch
Because of too short device legs, bent too close to board

 

[juma]

...these boards work fine, ...

Please, check orientation of Q1 - it looks like it is turned the wrong way around.

 

[hesener]

Hi chchyong89, is this a regular "electricians" screwdriver you are using (that is mainly used for testing line voltages)?

 

[awc]

When it sounds as good as this and other guys with high end gear agree, I dont care if all the component are inside out its sounds amazing.

Id like to make it dual 18v 300va I reckon it needs more VA.
how would I do that with out making it a dual Mono ?
join another 2 rectifiers + to +, - to -, another bank of Caps then ov to ov, would it Parallel lik that ?

That would give it 32 caps in total.

 

[sutantoroy]

Anyone ever tried F5 PCB from Jim's Audio (Hongkong)? Is it layot okay/correct?

 

[awc]

Anyone ever tried F5 PCB from Jim's Audio (Hongkong)? Is it layot okay/correct?

Thats what mine is as you can always tell by the way the F5 is written on them, and once again they sound fantastic.

 

[chchyong89]

^i am curious about the connection of Q1 too

 

[sutantoroy]

Another question to ask...

Is it okay if the position of TH2 (4k7 Ohm) is reversed with R16 (2k2 Ohm)? Because they are in series connection, it would have the same final value right? Are there other specifics purpose on its placing?

 

[jackies]

Also, in PSU, is there a point of putting a capacitor between + and -? Provided I already have enough capacitance?

 

[acold7dusta]

like snubbers?

 

[jackies]

Of course I like snubbers!

I'm asking if there's any benefit from an additional (large) capacitor that is connected between positive and negative power rail, as opposed to existing capacitors that are rail-to-ground.

 

[jackies]

Hah!
After a thorough search found a dedicated thread:
http://www.diyaudio.com/forums/power-supplies/164076-comining-rail-rail-rail-ground-decoupling.html
Apparently the conclusion was that it's pointless, at least from a theoretical standpoint.
But in this thread a person reports that he witnessed reduced sagging:
http://www.diyaudio.com/forums/powe...-directly-rail-rail-excluding-center-tap.html
Any other experiences?