F5 power amplifier

[udailey]

Might be better using those to power an Aleph Mini. Boards are available for CHEAP from chipamp.com at the bottom of the order page.
Uriah

 

[nicoch58]

thanks I know the miniA but I will have a used F5 board.....if can work with 15vac , 8 amp per side ?

 

[Nelson Pass]

What is the purpose of the // capacitor between the thermistors on the 120Vac PS?

It reduces hi frequency line noise, both incoming and outgoing.

 

[Renron]

Thank you Papa.

Ron

 

[bobodioulasso]

can try power the F5 with two 120VA 15vac r-core from seletronic ?

Yes you can if you slightly lower the bias .

 

[nicoch58]

burning trafo

 

[bobodioulasso]

Did you burn it trying with F5?
No mains fuse?

 

[nicoch58]

I joke I mean that trafo will run hotter

any one can report what gain in sound with dual mono psu ??

or at last one trafo and dual mono cap/diode......

 

[AndrewT]

I reckon a pair of monoblocks always sounds better than the same amplifiers built into stereo amplifier case irrespective of whether one or two transformers are used to power the two channel amplifier.

 

[labjr]

I reckon a pair of monoblocks always sounds better than the same amplifiers built into stereo amplifier case irrespective of whether one or two transformers are used to power the two channel amplifier.

Are you saying that separate cases make a larger difference than using separate transformers?

 

[nicoch58]

good point ! plus advantage to put near the speakers with short cable

 

[nicoch58]

two trafo, small space, a lot crossotalk and eddycurrent

 

[bobodioulasso]

I joke I mean that trafo will run hotter

any one can report what gain in sound with dual mono psu ??

or at last one trafo and dual mono cap/diode......

A normal F5 channel draw 25v x1.3A x 2halves = 65w

The stock F5 (http://www.6moons.com/audioreviews/firstwatt7/f5_2.html)

works with a 300va trafo which is 150va per channel


One channel supplied at +/-20v dc and biased at 1.3amp will draw

20v x 1.3A x 2 = 52w

120 va per channel is ok. even without lowering the bias.

If you are afraid, you can start with 1A bias

20v x 1 x 2= 40w your trafo is 3 times this power.

 

[AndrewT]

Are you saying that separate cases make a larger difference than using separate transformers?

I cannot confirm that.
Just that monoblocks are always better sounding.

 

[nicoch58]

thanks a lot , as I need a buy two 300va for my Erno amp ,4 are too much money

reuse are eco friendly

 

[nicoch58]

smart trick

 

[nicoch58]

I prefear use franch r-core trafo and FR ,girl too

 

[Razorblade]

Hey,

since i am building two F5 Monos at the moment, can anybody help me out with some questions regarding the power supply?

I have already posted it here

two pages back

For example: in spice simulation i get a power dissapation of ca. 100mw when using 0.15 Ohm resistance in a crcrc configuration, wouldnt 1 3w resistor be enough then?

 

[AndrewT]

what would be the peak current through the 0r15 if the speaker load demands 20Apk?
Most of that peak demand will be met by the last cap in the chain.
What percentage of rated dissipation would you aim for in the or15 for transient demands and continuous demands?

 

[brianco]

HELP NEEDED in UK PLEASE

Can any Uk or Euro member recommend a supplier for the Power Supply caps and inductor coils. I have searched and other than a few difficult to understand sites can find little suitable. I would naturally like to get both from the same source as a single order.

I am also looking for adequate heatsinks for this amp and am having similar trouble in finding well specified items in small quantity.

Many thanks for any replies.

Brian