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F5 build questions thread

B

booja30

pfm Member
Rather than creating a new thread each time I have a question I thought I'd try a general purpose thread and ask questions as they come up. Thanks for your patience and help in advance!

First question:

I'm getting ready to order a transformer for a DiyAudio FirstWatt F5 build (25w class A). This transformer meets the build guide recommendations (400-500VA, 2x18V):

https://airlinktransformers.com/pro...toroidal-transformer-standard-range-cm0500218

There are three 'customization' options at the bottom of the page (click the Customize tab). The second option splits the primary so you can wire parallel/series for NA and EU voltages (I've done that conversion before on a Naim tuner so that all makes sense).

The other two options are what I need help with. There's a £9 electrostatic screen (copper foil) option and a £7 EMI/RFI shield option. Are either of these worth it and/or necessary for this application?
 
Jez will be able to answer that - I have no hands-on experience although given the tiny proportion of the overall cost I'd probably go for one or t'other.

Unlike the F5, the M2 has a transformer in the signal path and with that comes the potential to pick up noise from the mains wiring. I mounted the mains transformer vertically and used one of these: https://www.aliexpress.com/item/32266289460.html?spm=a2g0s.9042311.0.0.37404c4dgtv4gk And it's quiet.

I'm too long in the tooth to have great hearing, but it still seems to me that our brains are 'trained' to ignore very low level noise, so most of us don't hear it. But as soon as it's removed we rave about 'inky black backgrounds' and micro detail suddenly becoming audible. Unlike a manufacturer, you can define your own budget and take every precaution you can think of to make your amp as silent as it can be. Given the cost of the chassis and psu, it makes no sense not to spend the extra 5% if that's what it takes. (I haven't costed my M2 - too busy enjoying it. But from memory the commercial version would have set you back $3,600, the F5 a bit less. so it's still going to be a bargain:))
 
As above really.... it's likely to make bugger all difference but for the few quid extra you may as well go for it.

As an aside, folks do seem to obsess about things that are going to make bugger all improvement... aside from the foo stuff that cannot make any difference at all under any circumstances (hifi mains leads, foo fuses etc) it gets forgotten it seems that eg a MC phono stage is about 2000 times more sensitive to noise and interference than any power amp!
 
Some things got lost in the mail and for some reason it took 3 weeks to get more leaded solder so I was dead in the water.

But it gave me a lot of time to figure out a good layout and simplify. That's good because I need room for a soft start board, a speaker protection board, and a second transformer for the speaker protection board. I'm also doing a lifted ground (probably got that term wrong) between audio neutral and chassis ground using a big diode bridge instead of a CL-60.

But yeah, I'm excited to be getting back to it again!
 
I'm in Spain but thanks for the offer!

I decided to put together another Mouser order on Friday. It left Texas that evening and arrived at my door in Valencia Monday morning. That was with free shipping!

I guess I'm a big Mouser fan now!
 
Here you go @Luca!

49855691587_b31b4712b4_b.jpg

49855388201_6bd1a7b7b8_b.jpg


The amp boards have been removed because they have a few fragile parts and I've been mostly working on the wiring of the PSU, soft start and speaker protection. I've had some extra fun designing and 3D printing some brackets to hold the PSU board vertically and the speaker protection above the transformer.

I still have to run power from the PSU to the amp boards, connect the inputs to the amp boards, and connect the amp boards to the speaker outputs via the protection board.

I'm already thinking about a preamp project next. I'm a bit tempted to look for a cosmetically ugly but good preamp to disassemble and rebuild into a ModuShop/Hifi2000 case. I find tone controls useful on occasion and not a lot of the DIY boards have them. If I build one from kit boards it'll probably be the DiyAudio Mezmerize B1 buffer (no gain).
 
booja30 said:
Here you go @Luca!

49855691587_b31b4712b4_b.jpg

49855388201_6bd1a7b7b8_b.jpg


The amp boards have been removed because they have a few fragile parts and I've been mostly working on the wiring of the PSU, soft start and speaker protection. I've had some extra fun designing and 3D printing some brackets to hold the PSU board vertically and the speaker protection above the transformer.

I still have to run power from the PSU to the amp boards, connect the inputs to the amp boards, and connect the amp boards to the speaker outputs via the protection board.

I'm already thinking about a preamp project next. I'm a bit tempted to look for a cosmetically ugly but good preamp to disassemble and rebuild into a ModuShop/Hifi2000 case. I find tone controls useful on occasion and not a lot of the DIY boards have them. If I build one from kit boards it'll probably be the DiyAudio Mezmerize B1 buffer (no gain).
Click to expand...


Great work!!!! Congratulations. I hope it will sound so good as it looks ...
 
booja30 said:
Here you go @Luca!

49855691587_b31b4712b4_b.jpg

49855388201_6bd1a7b7b8_b.jpg


The amp boards have been removed because they have a few fragile parts and I've been mostly working on the wiring of the PSU, soft start and speaker protection. I've had some extra fun designing and 3D printing some brackets to hold the PSU board vertically and the speaker protection above the transformer.

I still have to run power from the PSU to the amp boards, connect the inputs to the amp boards, and connect the amp boards to the speaker outputs via the protection board.

I'm already thinking about a preamp project next. I'm a bit tempted to look for a cosmetically ugly but good preamp to disassemble and rebuild into a ModuShop/Hifi2000 case. I find tone controls useful on occasion and not a lot of the DIY boards have them. If I build one from kit boards it'll probably be the DiyAudio Mezmerize B1 buffer (no gain).
Click to expand...
That is looking very smart indeed...
 
Thanks! Building is the most rewarding part for me, and given that I have so much time lately, I totally don't mind getting a bit OCD with the layout.

I could potentially have this thing ready to calibrate in a day or two, but there's no rush since I don't have a preamp to pair it with (my current setup is an integrated). I could try a ChromeCast Audio with variable output into it, but there's something reassuring about having at least a potentiometer between a source and power amp.
 
booja30 said:
Thanks! Building is the most rewarding part for me, and given that I have so much time lately, I totally don't mind getting a bit OCD with the layout.

I could potentially have this thing ready to calibrate in a day or two, but there's no rush since I don't have a preamp to pair it with (my current setup is an integrated). I could try a ChromeCast Audio with variable output into it, but there's something reassuring about having at least a potentiometer between a source and power amp.
Click to expand...

Why you don't pair it with the Naim Nac 72? I use Naim pre and power amplifier together or matched with amps of different brands with very good results.
 
Luca said:
Why you don't pair it with the Naim Nac 72? I use Naim pre and power amplifier together or matched with amps of different brands with very good results.
Click to expand...
I sold my Naim and Quad items a while ago and at the moment have a Rega Brio-R (the older one) and a Sony TA-F3000, both integrated amps.
 
booja30 said:
Here you go @Luca!

49855691587_b31b4712b4_b.jpg

49855388201_6bd1a7b7b8_b.jpg


The amp boards have been removed because they have a few fragile parts and I've been mostly working on the wiring of the PSU, soft start and speaker protection. I've had some extra fun designing and 3D printing some brackets to hold the PSU board vertically and the speaker protection above the transformer.

I still have to run power from the PSU to the amp boards, connect the inputs to the amp boards, and connect the amp boards to the speaker outputs via the protection board.

I'm already thinking about a preamp project next. I'm a bit tempted to look for a cosmetically ugly but good preamp to disassemble and rebuild into a ModuShop/Hifi2000 case. I find tone controls useful on occasion and not a lot of the DIY boards have them. If I build one from kit boards it'll probably be the DiyAudio Mezmerize B1 buffer (no gain).
Click to expand...

Just wow ! I personally love the heat sinks, a class A deserves this !
 
Gervais Cote said:
Just wow ! I personally love the heat sinks, a class A deserves this !
Click to expand...
It's a Deluxe 4U chassis from ModuShop/Hifi2000 in Italy that they make for DiyAudio. The sinks are pre drilled and tapped for DiyAudio's 'universal mounting specification' which will work for most of the projects on their site. The version with the 10mm bare aluminum faceplate also has holes for mounting things like the PSU board but I wanted a black faceplate, so I had to get more creative with layout and making parts. It's been a great project so far.

We'll see if I still like it when it gets above 40C here this summer. :p
 
booja30 said:
It's a Deluxe 4U chassis from ModuShop/Hifi2000 in Italy that they make for DiyAudio. The sinks are pre drilled and tapped for DiyAudio's 'universal mounting specification' which will work for most of the projects on their site. The version with the 10mm bare aluminum faceplate also has holes for mounting things like the PSU board but I wanted a black faceplate, so I had to get more creative with layout and making parts. It's been a great project so far.

We'll see if I still like it when it gets above 40C here this summer. :p
Click to expand...

For this reason I keep Naim, as alternative to my tubed amps, especially for a summer cold-listening. :)
 
I'm already thinking about a preamp project next. I'm a bit tempted to look for a cosmetically ugly but good preamp to disassemble and rebuild into a ModuShop/Hifi2000 case. I find tone controls useful on occasion and not a lot of the DIY boards have them. If I build one from kit boards it'll probably be the DiyAudio Mezmerize B1 buffer (no gain).
Click to expand...

In my opinion the F5 needs some gain from a preamp. I am using a Salas DCG3,its a good design and you can set the gain. Mine is set at 3Xand seems to work really well.

Fantastic looking build by the way!

Cheers
Ian
 
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