F5m kit

[Ylab]

around 40dB feedback.... in Spice.

Hi Generg,

where is node 003 and 004 on your schematic? Trying to understand how you have calculate this 😅

Hubert

 

[Toys4Boys]

Why so many parts LOL! Would it be letting the cat out of the bag, how many kits in the first batch?

 

[6L6]

Fewer than 600,000. From what I’m led to believe…

 

[Zen Mod]

it seems only I, ZM Mighty, is keeping so-so overall balance .........with parts count in any particular build

Pa keeps shaving numbers, so what's left to me, to keep increasing them

 

[Mark Johnson]

... bypass the source resistors of the output fets with say 1F or 3,3 F supercaps?

It might be a good idea for you to calculate the (AC) current through each source resistor bypass capacitor, when the amplifier is delivering 40 watts RMS into a 4 ohm load.

Are supercapacitors available, whose datasheets guarantee a ripple current capability that is acceptably large? Are those supercapacitors expensive? How big are they, physically?

 

[Toys4Boys]

Fewer than 600,000. From what I’m led to believe…

Everyone's a comedian The question wasn't frivalous, today I'm on the road with limited iternet access.

 

[EUVL]

logically, this one isn't intended for specific form factor of FW cases

Sounds like you are now the official press secretary for Pass Labs / First Watt / Nelson ?




Patrick

 

[Zen Mod]

I'm just fave Pet, with few spy Birdies in SR Facilities

Besides being sole proprietor of OPLDF

 

[generg]

Hi Generg,

where is node 003 and 004 on your schematic? Trying to understand how you have calculate this 😅

Hubert

Node 3 is at the gate connection of the J-fets and node 4 is where the feedback resistor wire meets the J-fet sources. The node numbers changes with every new added component or change in the circuit. So you must have a new look for the node numbers.

 

[WBS]

In the BOM there is mentioned for Q3 the IRFP9240. Is this a typo?
The circuit shows the IRFP9140.

IRFP9140 is correct.

 

[captain pugwash]

The usual First Watt cases are too big for my needs but they do allow things to be nicely spaced out inside. I have a case in mind for this project (the 250mm long version of an ACA case) but it would mean that the 3 boards and transformer would be quite tightly packed. I'm wondering if there would be any issues with hum or interference if I were to attempt this ?.

 

[Zen Mod]

dissipation?

 

[Logic800]

Similar thinking to Capt P, but whatever is the proper chassis size perhaps we should think of a UK group buy from Italy?

 

[Mikerodrig27]

Man, this is going to be a great amp for people wanting to get into amp building. Very cool! I like the thermistors replacing the resistors in the CRC power supply. Two less parts. Pretty clever.

 

[captain pugwash]

Similar thinking to Capt P, but whatever is the proper chassis size perhaps we should think of a UK group buy from Italy?

Well I already have one of these https://modushop.biz/site/index.php?route=product/product&path=284&product_id=733 which is the ACA case but with 5cm extra on the heatsink. It is rated at 0.47 C°/W. I'm looking for the smallest case possible (minimalist right?). The 3 cases quoted in the F5m pdf are all a tad too big but I'm not sure if there's enough breathing room inside.

 

[Toys4Boys]

I'm not seeing the chassis that Papa referred to in the build document, can someone enlighten me?

 

[captain pugwash]

Last page, top paragraph there are 3 "Diss" cases (Dissipante from modushop in Italy).

 

[km]

It might be a good idea for you to calculate the (AC) current through each source resistor bypass capacitor, when the amplifier is delivering 40 watts RMS into a 4 ohm load.

50 watts into 4 ohms is 5A peak 10F supercap is rated for 10A, they are small and cheap, I think I will give it a try

 

[Toys4Boys]

Last page, top paragraph there are 3 "Diss" cases (Dissipante from modushop in Italy).

Yes, and it said available in the store, I assumed that meant the DIY Store.

 

[captain pugwash]

Aha, see what you mean now, you can't find them in the store, agreed. For others reading this if you just search on "2U" and "3U" in the store instead of going to the chassis section you find a whole range of cases including the 3 in the F5m pdf but it seems that the store doesn't actually stock these.