DIY FirstWatt F4 and McIntosh C48?

[Rosewind]

Thanks! That is very helpful again. Much appreciated!

I have an Avondale soft start module, so I won't need the CL60 thermistor, right?

 

[2 picoDumbs]

Not for soft start but you'll want one linking psu ground to chassis ground

 

[Rosewind]

Thanks. Will do.

 

[Rosewind]

An externally hosted image should be here but it was not working when we last tested it.

 

[Rosewind]

Pictures of most of the loot:
Components, wires, screws etc., back panel, ready-made Avondale soft start module, BA-2 VAS board (unstuffed), populated f4 amp boards, populated psu board, transformer.

https://onedrive.live.com/redir?res...76&authkey=!APxFJ361POxxq44&ithint=folder,jpg

Arriving this coming week:
2 bridge rectifiers
CL60 inrush current limiter
Connection bridge
IEC power input + switch

Then I will begin planning the build and begin my journey towards understanding how to wire this little beast up for use with balanced inputs (XLR) and for use with soft start and BA-2 VAS module.

 

[Rosewind]

Oh. The predrilled holes in the heat sinks do NOT match up with the v1 F4 power AMP boards, so I will only be able to fix the two boards with two screws each at the top. The lower part of the boards will merely rest on standoffs. The legs of the 6 jfets will help hold the board fixed to the side, however. Would that be a problem?

I am running low on space in the cabinet so the psu will be placed on 8 cm standoffs above the transformer right up front. I will place the soft start module next to the transformer and run the power wires below the amp between the two bottoms of the 4u Deluxe enclosure.

The pre-amp VAS module will be placed centrally at the back of the cabinet.

Tomorrow I will build the enclosure and drill a big hole in the bottom for the transformer bolt. Then I will fix it securely to the bottom. After that I will screw the jfets onto the heat sinks and match up the amp boards to make sure they fit. Pictures forthcoming.

 

[KevinHeem]

Oh. The predrilled holes in the heat sinks do NOT match up with the v1 F4 power AMP boards, so I will only be able to fix the two boards with two screws each at the top. The lower part of the boards will merely rest on standoffs. The legs of the 6 jfets will help hold the board fixed to the side, however. Would that be a problem?

So the holes for the all the mosfets line up? I would drill and tap two holes in each sink just to be sure. If you haven't drilled and taped holes before I can walk you through it. It's really pretty easy, especially because you aldeady have two that line up. Do you have access to a drill press?

 

[2 picoDumbs]

If you're using CL-60s do you really need the soft start?

CL60 is to link PSU ground to chassis ground

 

[KevinHeem]

Sorry, I was still editing. I took that part about the soft start right out of my post.

 

[Rosewind]

Yes the mosfets do, actually. The v1 board is about 1/2 inch shorter at both ends.

I may be able to borrow a press drill at work / have the work done there. I will see next week. I feel more comfortable with the amp boards properly attached to the heat sinks.

 

[Rosewind]

https://onedrive.live.com/redir?resid=BFABEA7F02E245EC!7352&authkey=!AI0T9OvoFSyjx1I&v=3&ithint=photo%2cjpg

Changed layout with gain board on the back plate. The psu can then just fit in the enclosure.

 

[Rosewind]

Alright. I have decided to buy a small Bench Drill and to tap all new holes that match up with the v1 First Watt f4 amp boards. Then I may also decide to mount the PSU on the inside of the front panel.

So I will most likely press buy on these today.

 

[KevinHeem]

Drill Press

A drill press is always a handy tool to have, but you do have another option. You could always buy the F4 V2 boards from the store and put your V1 boards up for sale in the swap meet. Just an idea.

 

[MASantos]

I also have a F4 v1 board, and I thought of making some aluminum rectangular standoffs, one will attach to the heatsink's hole and the other will attach to the board.
Another option is to glue two standoffs side by side with some heat resistant epoxy glue.

Drilling the heatsinks might be the easier route, but there are other options if you don't have access to a drill press!

 

[Rosewind]

Thanks. I have (almost) everything sitting in my workroom. Still waiting for the small drill press and the tools needed to tap threads into the holes. I may still mount the psu on standoffs. I will see when everything is here.

Kevin. My boards are already stuffed. Buying v2 versions would mean that I would have to stuff that too (apart from the BA-2 board).

Question re. the BA-2 board: do I need to use any heatsinks anywhere on that board?

Kind regards,
Peter

 

[KevinHeem]

How's it going

Just wondered how your build is coming along. Have you had time to work on it lately? Maybe you're done and just listening to music.

 

[Rosewind]

Hi Kevin.
I have all the bits in the house give or take a few bits and bobs. All I need is time. Currently I am in Tenerife, tomorrow will see me back in Denmark and I will have a hard look at the task ahead of me Thursday. Most likely I will drill and tap a few holes in order to mount the amp modules and the psu properly in the 4U deluxe enclosure. Then it will be time for mounting everything but the pre amp board.
Kind regards
Peter

 

[finwbu]

BA1 F4

Hi,

if someone looking for Boards i have 5 or 6 Boards available and partly assembled.The price per Board is 8Euro.The Shipping from Germany by DHL.

Br Walter

 

[Rosewind]

Just a Quick note. I have just broken a bone in my left hand wrist, so my cunning plan to work on this build during Easter has had to be postponed. I may have to wait as long as 8-12 weeks before the break has healed. Never try to haul branches and cut-off shrubbery off a closed trailer with all your force and weight. I fell backwards and my left hand bore the brunt of the fall. A bone below the thumb may have broken all through. An MR scan will determine that.

I am busy correcting students' mid-term essays with my right hand. I am not in any pain, thankfully. Had I broken my right hand I would be able to look forward to piles of English essays that I could not in any way correct ... for too many weeks.

 

[albertNL]

Hope it heals quickly!