diyAudio F5 Build Guide

Thx Dennis, 6L6.

Depends on how you build your PSU. If I were rebuilding mine I’d use monolithic diode bridges and the CL-60 soft start so I could place the transformer toward the front and the CR filter toward the rear, similar to the real First Watt F5 design. With discrete diodes and the soft start board, I didn’t have space for the DIY Audio Store CR filter board anywhere but attached to the face plate. I think this layout could be what’s causing the slight hum in my F5 build.
 
Depends on how you build your PSU. If I were rebuilding mine I’d use monolithic diode bridges and the CL-60 soft start so I could place the transformer toward the front and the CR filter toward the rear, similar to the real First Watt F5 design. With discrete diodes and the soft start board, I didn’t have space for the DIY Audio Store CR filter board anywhere but attached to the face plate. I think this layout could be what’s causing the slight hum in my F5 build.

Thx jphabc54. I was planning on building the PSU pretty much per 6L6's build guide linked to in the store. The F5 layout would be much along the lines of his build guide on that as well. I was part way through a build on a Hypex class D amp when I received and finished an ACA first, so I happen to have a nice soft start module and a push button switch with an led ring around it I thought might look great on the black deluxe 4U chassis. I'll have to wait for the chassis to see how I will lay it all out. Any pics of your amp would be great.

Please explain a bit about this CR filter. I do not see anything about it in the store nor do I recall reading about it.

Thx
Dave.
 
Thx jphabc54. I was planning on building the PSU pretty much per 6L6's build guide linked to in the store. The F5 layout would be much along the lines of his build guide on that as well. I was part way through a build on a Hypex class D amp when I received and finished an ACA first, so I happen to have a nice soft start module and a push button switch with an led ring around it I thought might look great on the black deluxe 4U chassis. I'll have to wait for the chassis to see how I will lay it all out. Any pics of your amp would be great.

Please explain a bit about this CR filter. I do not see anything about it in the store nor do I recall reading about it.

Thx
Dave.

Hey no problem — by CR board I meant the capacitor bank part of the Universal PSU. To make everything fit in the 4U chassis, I had to separate the rectifier and capacitor bank components of the PSU board and attach the capacitor bank to the front panel. Unfortunately this layout put my transformer in a loop with my preamp. I got some good advice on adjusting my wiring to minimize the loop, but I still have a very faint 60hz hum on my F5 when it’s attached to a preamp.

I posted some pictures of my build and a discussion of my hum challenges beginning here in the F5 Power Amp thread:

F5 power amplifier
 
Hey no problem — by CR board I meant the capacitor bank part of the Universal PSU. To make everything fit in the 4U chassis, I had to separate the rectifier and capacitor bank components of the PSU board and attach the capacitor bank to the front panel. Unfortunately this layout put my transformer in a loop with my preamp. I got some good advice on adjusting my wiring to minimize the loop, but I still have a very faint 60hz hum on my F5 when it’s attached to a preamp.

I posted some pictures of my build and a discussion of my hum challenges beginning here in the F5 Power Amp thread:

F5 power amplifier

Hey this is great! Thanks. I've built the ACA and a couple Elekit tube amps so I haven't been fretting too much about most of it - but the biasing part is new to me ... and when the guys get to talking about firing the amp up the first time with a light bulb in the loop or a variac, it gets me slightly nervous.
 
Well, after some fun with FedEx, my chassis finally arrived. 5 days from Italy to Edmonton where it sat for 5 more days with a delivery pending notice.... which then went to "delivery date unavailable". I had to spend quite a bit of time figuring out that FedEx wanted customs fees from me but once paid it was here the next day.
So far everything seems to be going rather nicely. I have a few remaining resistors and LEDs on the way, and other than having to drill out the back plate to accept the RCA blocks properly, all is looking rather nice. I see there's a fuse block for a couple of 250V fuses in the power supply module. I don't suppose anyone has a Digikey or Mouser PN for these? I don't believe I'll be finding these in town here...
20190305_192608.jpg
 
How about 5 amp slow blow? I went to my local "The Source".... (I miss when it used to be Radio Shack and they always had tons of fun stuff. Now it's all about smart watches and Beats headphones). Anyways, I found a 2 pack of 250v x 5 amp slow blow fuses. The only fuses in the store. Is 5 amp suitable?


Circuit Protection
Take a look at section 6 Application to get some ideas to think about.


If you've built your F5 with a transformer in line with the original design:
http://www.firstwatt.com/pdf/prod_f5_man.pdf
then 5A looks over sized. Take a look at the manual and you'll find relevant commentary that should help you out.
 
Really appreciate it astromo. Oddly enough, I found the information right where it probably should be, in the schematics: 2.5 slow. Reading schematics is like reading sheet music, I'm not very good at it - and being a drummer, I'm generally forgiven for not being able to understand it anyways. I sent a query off to the DIY store as well and they suggested a 3 amp fastblow.
 
PSU Filter capacitor value?

Hi, I see 4x 22,000’s (per side) in 6L6’s guide, whereas the original schematic from Papa had 15,000’s - and some have used 10,000’s “because that’s what they had.”

I’ve been trying to figure out from reading and researching how to optimally figure filter capacitor values. I believe I’ve read conflicting reports about how much is enough versus too much filter capacitance in a system.

For my build, I’m using the AnTek AS-4218 400VA 2x0-18, and I’m using the psu board from diyaudio.

So I have two questions:
1. What value filter capacitors should I buy for my system?
2. Why? (what’s the math/magic formula, or what article should I read)
 
Really appreciate it astromo. Oddly enough, I found the information right where it probably should be, in the schematics: 2.5 slow. Reading schematics is like reading sheet music, I'm not very good at it - and being a drummer, I'm generally forgiven for not being able to understand it anyways. I sent a query off to the DIY store as well and they suggested a 3 amp fastblow.

Had the same question myself. Building the F5 using the store back panel kit and guide from 6L6, F5v3.

2.5 amps, slow blow I think is correct

Just make sure the cartridge is also the correct size.


I used the guidance in the link I noted back in Post #70 diyAudio F5 Build Guide
for a Universal PSU build for an Aleph J that I've recently completed but used a large transformer than standard. I've eyeballed a crappy wall plug "watt meter" and its reading a starting and operating current in line with that intel, so I'd say it checks out.


The First Watt F5 manual that I linked to concurs with Tuberoller. Take a look on p.18.
 
Well, after some fun with FedEx, my chassis finally arrived. 5 days from Italy to Edmonton where it sat for 5 more days with a delivery pending notice.... which then went to "delivery date unavailable". I had to spend quite a bit of time figuring out that FedEx wanted customs fees from me but once paid it was here the next day.
So far everything seems to be going rather nicely. I have a few remaining resistors and LEDs on the way, and other than having to drill out the back plate to accept the RCA blocks properly, all is looking rather nice. I see there's a fuse block for a couple of 250V fuses in the power supply module. I don't suppose anyone has a Digikey or Mouser PN for these? I don't believe I'll be finding these in town here...
View attachment 740885

You can get some cues from this piece:

Back panel parts kit plus PCB / Transistor / Diode mounting parts kit – diyAudio Store

As per the intel above, if you got yourself a UMS chassis from diyAS, these receptacles (or similar) should fit:
Please complete the security check - Octopart
Please complete the security check - Octopart
... worked for me.

... and the power entry module from the store page. I went for one with a green LED.
 
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I hope its ok to reply in this thread.
Was planning on building the F5 and just wanna make sure I got it all.

From The diyAudio Store
- F5 boards
- F5 kits part kit
- Deluxe 4u aluminium + back panel kit
- Linear Systems Matched Lsj74/Lsk170 JFET Pairs
- Universal Power Supply

Other
- Transformator 500VA - Would this be a good match? http://www.sedlbauer.de/media/ringkerntrafo_datenblatt_826058_e.pdf
- Parts for Universal Power Supply


Seen these rectifier blocks but my local store doesnt carry them, anyboy who know where I can find them?
Rectifier-block — imgbb.com
 
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Thanks for the quick reply.
Saw even bigger transformers in other build so kind of settled for this one. Will take a look at the price difference for a smaller one. Thanks for the link to the bridges form Mouser.

At the moment I'm looking for a good store for components. Recommendations would be awesome, preferably in EU but not necessary.
 
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