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first watt f5

P

philiphifi

pfm Member
hi - i just been on the diyaudio and read reviews on the FW F5. Is it true that the sound is that good? It is easy to build and doesn't cost that much
 
Yes, yes, and yes. It’s only 25 watts per channel into 8 ohms, so you’ll need fairly efficient speakers. The F5 has a very precise/accurate sound.
 
I've built, well transplanted a F5T, 50 watts and it does sound really good.

This thread needs to be moved over to the DIY room.
 
I have the F4. It has no feedback and no voltage gain, only current gain. It needs a pre with sufficient output to drive it but I find it sounds fabulous with my Tubes4hifi valve pre. Again, efficient loudspeakers are required. My Ref 3a speakers are >90dB.
I've read that Mr Pass' favourite designs however are single ended. Must try one sometime. The great thing is that once you have the case and psu you can try different amplifiers. When I get the time I will try converting my F4 to a 'Sissy Sit' with VFETs.
 
Avinunca said:
I have the F4. It has no feedback and no voltage gain, only current gain. It needs a pre with sufficient output to drive it but I find it sounds fabulous with my Tubes4hifi valve pre. Again, efficient loudspeakers are required. My Ref 3a speakers are >90dB.
I've read that Mr Pass' favourite designs however are single ended. Must try one sometime. The great thing is that once you have the case and psu you can try different amplifiers. When I get the time I will try converting my F4 to a 'Sissy Sit' with VFETs.
Click to expand...

I have a pair of DIY Aleph 60 monoblocks - single-ended Class A. I heard a pair of SIT amps last year and they were stunning but cost a fortune.
 
I owned an F5.They sound nicely open and clean and image well but are really boring sounding.All the audiophile qualities are there but they just do not engage you with the music and lack vibrancy.Which is a bit odd because they do not sound clinical or mechanical as is often the case with SS amps.There is just something fundamentally musically unconvincing about them.
 
As I understand it the F5 is pretty lean and clean.

The F6 is sweeter.

I prefer the M2 to the F6, very musical with a slight touch of softness top and bottom from the output transformers.

Any of his designs are well worth your time investigating. My M2 is a keeper.

Would be very interested to try the F4 though.
 
philiphifi said:
are they different to the commercial pass lab? these cost a fortune
Click to expand...

The diyaudio boards are identical to the commercial FirstWatt circuits. Those are about £3.5K so unless you like the Robot Wars looks of the official ones the DIY versions are a no-brainer.
 
thanks gents. What about the components and transformers? i built 2 preamps with different resistors and caps and they sound very different.
 
philiphifi said:
thanks gents. What about the components and transformers? i built 2 preamps with different resistors and caps and they sound very different.
Click to expand...

With the First Watt designs I probably wouldn’t be looking to swop in boutique parts.

However, my M2 did benefit from an improved power supply designed to reduce noise on the rails.
 
can i get all the parts including power supply from diyaudio or would you recommend a UK based firm (probably would be much easier)
 
They sometimes have full kits as well as boards but they are often out of stock. You’d have to check the store.

Otherwise Mouser / RS will carry most of the basic parts. You might have to look further afield for certain JFETS depending which circuit you decide to build.

There are full BOMs and illustrated build guides over on diyaudio.

It’s worth spending some time on the First Watt site getting your head round the different circuits, they are all pretty individual and some will suit your needs better than others.

I’d take an F6 over and F5 personally.
 
Hi Philip,
The F6 especially is very easy to build and gives excellent results. You can buy the kit of PCB and transformers from the DIYAudio shop and also some of the matched FETs as well. The rest of the components you can get from RS, Farnell, CPC, Rapid, and Cricklewood in the UK. As with all Pass circuits/kits it gives about 25 Watts of very clean audio.
One thing I would initially advise against is mounting the transformers on the PCB as they are susceptible to electromagnetic hum pickup from the power transformers. I attached mine using longish leads, about 10"/30cm long, and moved them around for minimum hum then fixed them in place using thin Ali strips, Tyraps and sticky pads. Residual hum and noise down in the -90dB WRT 775mV.

John
 
i.j.russell said:
I have a pair of DIY Aleph 60 monoblocks - single-ended Class A. I heard a pair of SIT amps last year and they were stunning but cost a fortune.
Click to expand...

The 'Sissy SIT' uses some devices originally designed for high current industrial applications. I bought mine from a diyaudio member seller in China. He may still have some. They are big beasts. The sissy sit thread on diyaudio has all the info. They are paired up with a mosfet - one of each per channel.
 
John Caswell said:
Hi Philip,
The F6 especially is very easy to build and gives excellent results. You can buy the kit of PCB and transformers from the DIYAudio shop and also some of the matched FETs as well. The rest of the components you can get from RS, Farnell, CPC, Rapid, and Cricklewood in the UK. As with all Pass circuits/kits it gives about 25 Watts of very clean audio.
One thing I would initially advise against is mounting the transformers on the PCB as they are susceptible to electromagnetic hum pickup from the power transformers. I attached mine using longish leads, about 10"/30cm long, and moved them around for minimum hum then fixed them in place using thin Ali strips, Tyraps and sticky pads. Residual hum and noise down in the -90dB WRT 775mV.

John
Click to expand...

Rivnuts are your frend for mounting toroids, they are like a internaly threaded pop rivit.
Buy a cheap tool and inserts from eBay etc.

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=264620515472

Pete
 
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John Caswell said:
Hi Philip,
The F6 especially is very easy to build and gives excellent results. You can buy the kit of PCB and transformers from the DIYAudio shop and also some of the matched FETs as well. The rest of the components you can get from RS, Farnell, CPC, Rapid, and Cricklewood in the UK. As with all Pass circuits/kits it gives about 25 Watts of very clean audio.
One thing I would initially advise against is mounting the transformers on the PCB as they are susceptible to electromagnetic hum pickup from the power transformers. I attached mine using longish leads, about 10"/30cm long, and moved them around for minimum hum then fixed them in place using thin Ali strips, Tyraps and sticky pads. Residual hum and noise down in the -90dB WRT 775mV.

John
Click to expand...
Thank you very much. On various forums, the F5 seems more popular than the F6. Is there a reason for that or is it just that it is new?
 
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