PSU
Thanks Jacco,
I think I will try something more than 60,000uf in each channel of F5.
Papa recommends about that in F5 article -
The noise of a properly laid out circuit is about 30 uV with a quiet supply, and raw supply with two 29,000 uF capacitor and
70 mV ripple will give about 100 uV noise (measured in the band from 20 to 20,000 Hertz).
Are you recommending 80,000uf?
I thought since this is class AB, the discharge may be quicker than say an F3. This may lead to needing more juice.
Always wanted to try 47000uf caps.
Thanks Jacco,
I think I will try something more than 60,000uf in each channel of F5.
Papa recommends about that in F5 article -
The noise of a properly laid out circuit is about 30 uV with a quiet supply, and raw supply with two 29,000 uF capacitor and
70 mV ripple will give about 100 uV noise (measured in the band from 20 to 20,000 Hertz).
Are you recommending 80,000uf?
I thought since this is class AB, the discharge may be quicker than say an F3. This may lead to needing more juice.
Always wanted to try 47000uf caps.
cviller said:
I haven't read the hole thread. He might have suggested that - i doubt ringing is a problem in this regulation...
I have uploaded a new layout - I still plan on ordering tonight, unless someone points out a blocking issue with my layout.
Look good to me, going over all the board connections
I get the feeling that you cannot make a mistake The thermistor issue can be handled with a dab of silicone sealant. Good heat transfer and can take quite some heat. I do beleive though, that Firstwatt just use the "leg bending"- technique and place the thermistor hovering right over the powerfets. Someone posted a picture somewhere, but I couldnt find it. Jacco?
steenoe said:
Look good to me, going over all the board connections
The thermistor issue can be handled with a dab of silicone sealant. Good heat transfer and can take quite some heat. I do beleive though, that Firstwatt just use the "leg bending"- technique and place the thermistor hovering right over the powerfets. Someone posted a picture somewhere, but I couldnt find it. Jacco?
Thanks for looking through the F5 pcb. What about the psu - it is so simple, but I might have missed something.
You can see the thermistor here:
http://6moons.com/audioreviews/firstwatt7/f5_2.html
cviller said:
PSoo look good too
It would probably be a good idea to fill the 3 plated via's on the neg. rail with some solder first.
One suggestion: a set of big solderpads at each rail, for if someone would use a CLC config would be nice. 2mm holes, sitting at the R sections....
BTW, very good idea with the output in the middle of the board. Makes for a much cleaner looking build.
mithomas said:
100uV referenced to 2.83V is -89dB.
It's not about noise, but impuls power, how important that is for you is determined by the behaviour of your LSP's.
Really good LSP's are usually not the most friendly, with a few exceptions.
A commercial example : Accuphase A-30, pretty OK power amp for $3.5K
Does 30W/8, dissipates a little over 80W per channel, a single 400VA transformer for both channels, has 47000uF per channel.
But : the vertical MOSFET output stage rails of the A-30 are a bit higher than 24Vdc, the lytics have more energy stored than the same cap value would have in an F5.
Plus : the Accuphase has separate regulated rails for the front stages, including the driver stage.
(the bigger buck A-60 brother has 82000uF per channel)
I'm not recommending anything.
The LSP's i have are tricky, so i tend to go for big caps.
Yours may feel pretty happy with less than 60KuF, not for me to say.
jacco vermeulen said:
Recommending big caps is always popular!
A promised in the beginning of this thread to make room for dale resistors, but I didn't think they were that big... now I have moved around a bit to make it possible to fit them.
Next up, the psu suggestions from steenoe.
Attachments
No refurb to the Spicas...everything is the factory original with these 2 speakers.
On the F5 thread, the consensus is that the Spica's are too inefficient (84 dB/W/m) for the F5s. I'll give it a go once the F5 is ready for its test drive.
Depending on how 2009 shapes up financially, I'll probably end up building a pair of speakers that are at least rated at 90 db/W/m. Then I will probably get that taste of heaven I crave.
I sent payment and again thanks! This will be my first amp to build. Total noob!
I can mail it to you - just send me a pm, but do you want the double sided or single sided?
BTW: I have stopped sending requests for a while because Paypal has limited my account. I have given them all the documents, but it might take some time for them to get to it. You can still send me GBF5_ORDER mails, but I'll just queue them until I can send request again.
BTW: I have stopped sending requests for a while because Paypal has limited my account. I have given them all the documents, but it might take some time for them to get to it. You can still send me GBF5_ORDER mails, but I'll just queue them until I can send request again.
Chokes and replies
I guess my request is one that will have to wait on your PAYPAL account to be updated. I will wait patiently.
Noticing the mention about using chokes in the PS: this is always a good idea. What is a suitable choke for this purpose? If you know I would greatly appreciate knowing where to look!
Thanks,
I guess my request is one that will have to wait on your PAYPAL account to be updated. I will wait patiently.
Noticing the mention about using chokes in the PS: this is always a good idea. What is a suitable choke for this purpose? If you know I would greatly appreciate knowing where to look!
Thanks,
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