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.
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
Last edited:
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.
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.
Last edited:
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.
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.
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.
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
Bridge Rectifiers Components Maplin
KBPC3504 B5 400 35 280 1.2V@17.5A
Last edited:
Thanks for all this information, it is very helpful, also to choose the correct heathsinks.
Yes, I've read the manual. It is very complete, compact and easy readable.
Thanks, Nelson!
Still, I need to simulate "my" psu, as I dont have a 18VAC trannie, but 20V.
Too high?
Do I have to waste some watts in higher R value in the CRC filtering?
Or do I better a CRCRC filtering, with this trannie?
Or do I wait till my money allows me to buy a 18V trannie?
Franz
Yes, I've read the manual. It is very complete, compact and easy readable.
Thanks, Nelson!
Still, I need to simulate "my" psu, as I dont have a 18VAC trannie, but 20V.
Too high?
Do I have to waste some watts in higher R value in the CRC filtering?
Or do I better a CRCRC filtering, with this trannie?
Or do I wait till my money allows me to buy a 18V trannie?
Franz
When I take my F5 (with 230V mains rating) to the UK - then the transformer started to hum. In the UK a real voltage in mains network was approximately 245V. In addition, the bias rises because the PSU Voltage increase of a few V. Perhaps it also depends on the quality of the transformer.
Now I am back from a few month business trip in my country - and transformer is silent. Here in mains - approx. 220V.
Now I am back from a few month business trip in my country - and transformer is silent. Here in mains - approx. 220V.
I think Peranders has something for this. I remember reading about this a while back.
sjostromaudio.com - DCT01 The DC trap, high-end style
True. It really is a fantastic article. I read it again a few days ago and learned more. Stuff I could not have understood the time I read it before this was now clear. There is still lots I dont understand in it and would be really nice if each paragraph was broken down yet further but man it sure is a nice article and I really appreciate the Pass Library.
Uriah
I would go with the 20v transfo. You will get 27 to 28 volts dc which should not kill the jfets.
If you are afraid of these few more volts you can cascode the jfets.( see Cviller blog) or even use an active filter which can drop out about 4 volts.( see zen v9 article)
