F5 power amplifier

[ichiban]

Originally Posted by Tripmaster

Thanks for that. It looks like you have a pair of Chris Wujek's heatsinks

Yes, good eye. Wish I had purchased four of these.

[Tripmaster]

Originally Posted by bobodioulasso

Most of the ever asked questions are answered in the pdf manual . From noise figures to heatsinks size. And a lot more. Reading it deeply is very informative.

Hi

Please excuse my ignorance, I am inexperienced! I have read through the manual on several occasions and just needed to clarify a couple points

Quoted from the manual

'The amplifier with 24 supply rails should be good for a 50 watt peak into 8 ohms, or about 2.5 amps.'

'The power supply of the tested amplifier is +/-24 volts and should be rated at 6 amps continuous duty, and more than 10
amps peak per channel.'


I will be driving FE167E 8ohm drivers.

Can someone please answer the following...?

What should the fuse holder, power switch, and the spade connectors attaching the ac/dc wires to and from the bridge rectifier be rated at? ~7-10 amps or am I completely missing the point?

Thanks

[AndrewT]

the fuse holder and the spades and the power switch will all see the current limited supply that the CL60s have ensured.
I would expect 10A rated components to be easily capable of meeting that duty.

The secondary side is completely different.
The 230:18+18Vac transformer effectively allows 6times as much current to flow through the rectifier and smoothing caps.

For a 2.6Adc continuous loading of two channels of F5 you need a transformer >=5.2Aac to run at maximum rated power.
To run cool the transformer rating should be roughly doubled, i.e. >=10.4Aac

The rectifiers will see very high, but short term, charging currents that are considerably bigger than the 2.6Adc load. They will need to be >10A and preferably ~25A and will also need to be cooled with heatsinks.

[Tripmaster]

Originally Posted by AndrewT

the fuse holder and the spades and the power switch will all see the current limited supply that the CL60s have ensured.
I would expect 10A rated components to be easily capable of meeting that duty.

Thanks Andrew I was having difficultly understanding the correct rated part in different areas of the amp.

Its good to know I don't need to source a new switch and fuse holder! The trouble with spade connectors is most are not rated all that high.

I have some of these... Lucar Female Connector Components Maplin

I emailed their technical dept. and the chap says they will handle around 15A @ 12VDC. I'm not sure how this translates into the voltages I will be dealing with.

[Tripmaster]

Oops you posted another reply, I missed that one.

Airlink Transformer
Primary 230Vac
Secondary: 2 x 18v @ 13.80A
Regulation: 6%

Just noticed they rate the primary winding at 230v

[AndrewT]

230Vac rated primary is not a problem.
They are designed to work on the full range of mains voltages from 220 to 240Vac.
The specified 230:18+18Vac tells you the turns ratio, after correcting for the 6% regulation. It looks like the ratio ~12.05:1+1

The 13.8Aac is comfortably above the 10.4Aac that I advised.

[Tripmaster]

I currently have a pair of these and I was going to either attached them to the main heatsinks or to a separate sink, with heat transfer compound in between.

Bridge Rectifiers Components Maplin


KBPC3504 B5 400 35 280 1.2V@17.5A

[AndrewT]

give the bridge rectifier/s their own cool heatsink. It does not need to be big to run much cooler than the 50degC or so of the mains sink/s

[Tripmaster]

Excellent!

I'll just solder the wires to the bridge and be done with it.

[umut1001]

I am using F5 amp with 2xKendeil capacitors of 68000uf plus 2x15000uf Rifa peh 169.I also have 8xBC 25v 47000uf each 4mohm esr capacitors.Is it possible to add them?Will be any problem then?I have 600va transformer and i connected 1 piece of cl60 in series to primary of transformer.