F5 power amplifier

[h_a]

@TheAnaesthetist: glad to hear you finished your amp and it's now up and running! I'm sure you'll enjoy it

Hannes

 

[thunk303]

Can the LighterNote be used directly with my f5??

I'm sure this must have been discussed at some point but I am buggered if I can find the posts.....

Cheers
Dean

 

[Sangram]

F5 has input impedance of 100K and should be fine with passive attenuators for the most part, IINM.

I used to use mine directly from the DAC outputs. The amp was not at all fussy or problematic when used this way.

 

[PB2]

A couple of volts. The losses are across the Source resistors and the saturation
voltage of the Mosfets.

Thanks Nelson, that's what I thought - just wanted to confirm.

 

[TheAnaesthetist]

great looking amp
Hifi2000 case ? Is It 4U 300 - you got right amount of space for a dual mono
I see that you use Amplimo toroids - what are their spec - what Is your bias, any hum from toroids

regards

Hi samaloko. Yes Hifi2000 4u 300 plus pierced base. Fits perfect.

Amplimo: 2x18V 225VA ringkerntransformator - Prim. spanning : 2x 115V

The tranformers are completely silent. Bias is now set at 0,6V ~1,3A. Temp of heatsink is appr. 48 degr. C but I am not sure about the thermometer. At least I can put my hand for more than 5 sec. on the heatsink which is a reliable test according to pappa N.

 

[wixy]

Anyone know where to buy PCB's for the F5? (if possible).

 

[Woody1911a1]

Anyone know where to buy PCB's for the F5? (if possible).

sure click on "Store" at the top of this page

cheers Woody

 

[wixy]

sure click on "Store" at the top of this page

cheers Woody

Thanks for that. PSU pcb's aren't available at the diyaudio store, can they be bought anywhere else?

 

[cviller]

Thanks for that. PSU pcb's aren't available at the diyaudio store, can they be bought anywhere else?

I have a few psu pcb's left (you can order them here: cviller order site ) and I think Peter Daniel also still has some left.

Br,
Christian

 

[TheAnaesthetist]

@TheAnaesthetist: glad to hear you finished your amp and it's now up and running! I'm sure you'll enjoy it

Hannes

Thanks Hannes,

I am enjoying it. I was intentionally worried about the combination DCB1 (no gain)-F5 and my 8 yr. old Dynaudio S25 but luckily there is a lot of emotion, subtility, nice stereoimage and enough dynamics to make me smile and enjoy the music. So I am satisfied.

Joffrey

 

[AndrewT]

I'm using 5x20mm 2.5A fuses (slow blow) for my F5. I just popped one with my transformer and bridges hooked up into the power supply unit.

Fuses, plural.
Where are they located?

 

[samoloko]

Thanks Hannes,

I am enjoying it. I was intentionally worried about the combination DCB1 (no gain)-F5 and my 8 yr. old Dynaudio S25 but luckily there is a lot of emotion, subtility, nice stereoimage and enough dynamics to make me smile and enjoy the music. So I am satisfied.

Joffrey

have you tried to hook F5 with pre Instead of buffer
I think that F5 having 100K Input does not need buffer

 

[PB2]

I was wondering Nelson if you had looked at this nearly comp pair from Fairchild:
FQA36P15/FQA28N15 in TO3P package and with gms of 19.5/20S, power 294/227W

Probably overkill for an F5 but I was thinking of a more powerfull design. The gm's
are significantly higher than other favorites on here.

 

[Nelson Pass]

I imagine the capacitance would be roughly proportional to the
transconductance.

 

[EUVL]

> FQA36P15/FQA28N15 in TO3P package and with gms of 19.5/20S, power 294/227W

Those gm values are at 18A. I guess you are not going to bias at 18A.
So at around 2A, gm would still be like 3S or so.


Patrick

.

 

[wixy]

Would anyone be able to advise the total approximate parts cost of a standard F5, using decent quality parts?

 

[AndrewT]

Hi Wixy,
a single channel F5 amplifier will cost ~£20 to £30.
The transformer + PSU + Heatsink + Chassis + Hardware could cost from a low of £20, if salvaged, to £1000 for new components. Using super quality parts expect >£2000 per channel.

 

[6L6]

wixy - I figure about $600-700 USD is what I have in mine. Your biggest variable is the chassis.

 

[Nelson Pass]

With a little resourcefulness, $200-$300

 

[labjr]

With a little resourcefulness, $200-$300

even less if one re-uses the chassis and PS from another F amp project.