F5 Turbo Builders Thread

Jump to Latest
#4,561
Yes, i guess that will be my best bet. Think 30W per dissapation is workable? I wanted to use the DIYaudio Store PCBs, 1N and 1P Channel would work out great spacewise but i guess i can work something bigger out. The more overall Bias the better the low impedance drive capabilities, that was the trick EUVL used to build the balanced f5x right? We need Amps not Volts.
 
#4,565
Dennis is correct, no need for cascode with normal voltage. Cascode gives easy chance to make more power through more voltage swing.

Either configuration will sound wonderful, there's something that sounds better , in my opinion, with paralleled devices.
 
#4,566
I ordered two of his boards. Will go non cascode, 24V 1.5A in search for some improved low z performance compared to my trusty F5s. I will build a stereo amp this time so i can use the softstart and dc protection pcbs from the diyaudiostore. I Kinda would feel safer to have these in place.

Any reconmendations on a powersupply? I was thinking 1000VA 2x18V on the Transformer but how much capacity?
 
#4,567
Assuming 2 pairs of output devices per channel and 1.5A per device, 1000VA
for the stereo amp will be more than adequate. I would be happy even with 800VA.

For capacitance, your current draw will be a bit more than twice that of the standard FW design
so perhaps about twice the standard amount as a guide?

Cheers,
Dennis
 
#4,569
Razorblade said:
...........Will go non cascode, 24V 1.5A .......... I will build a stereo amp ...............Any reconmendations on a powersupply? I was thinking 1000VA 2x18V on the Transformer but how much capacity?
Click to expand...
There are three ways to arrive at a suitable VA for the transformer.
a.) Follow Tomchr's design guide.
b.) Take the VA and divide by the Vac to arrive at Iac.
de-rate this for a capacitor input filter to get the max Idc (~50% to 60% of Iac) from the PSU. For cool running assume the continuous DC current is ~50% of Idc max.
c.) Multiply the total maximum ClassA output by 6 to 10

Answers
C.) gives six * {50W+50W} = 600VA to ten * {50W+50W} = 1000VA
B.) gives 2*2*(1.5A+1.5A+1.5A+1.5A)=24Aac which at 18-0-18Vac becomes 864VA
I have no intention of going through a.)

All of these methods are referred to repeatedly in this Forum. It's long past the time that we should still see the same question being repeated.

For PSU adopt any of the PASS recommended arrangements, or follow the Build Guides so kindly prepared by our Members.
 
#4,570
Erlend Sæterdal said:
Blew a pair of LSK 74/170 during adjustment, Now they are "sold Out" 😱
Click to expand...

Thats my problem too. I still got a lot of SK170, one matched pair of SK170 and SJ74, and two more matched pairs that are installed in my F5s, i dont really wanna rip apart my F5s. Since LSJ74 are only sold via diyaudio store , i guess i have to buy a pack of SJ74 and hope two of them match with my 170s

Andrew i knew the rough formula, i think Papa wrote it down in one of his Papers on Power supplies, but i cant find it anywhere. The other twomethods were unknown to me. I will go for the standart F5Tv2 supply and maybe up the caps a little bit. should be good to go. Cornell sell some pretty large 35V/47.000 Caps that have 35mm diameter and 10mm spacing so they should fit the diyaudio store power supply.
 
#4,574
Re First Build F5T

Hello all.

Thank you for such a wealth of information. I have been lurking around for a while and I have learned so much. I have started to piece together the parts for an F5T build. I could use some help choosing some parts.

If you feel up for some novice hand-holding drop me a line.

Thanks again for putting up some great resources.
 
#4,576
if they are at the top end of grade A lsj74 then they will work.
You will probably have to make small adjustments to some of the resistor values.

If they are middle to bottom end of Grade A, then they will not be close enough to the B or BL grade of the sk170.

Have you tested them using the Borbely jig for Idss and Vpinchoff? and calculated the gm?
 
#4,579
alexanderfa said:
I bought F5 V3 from diyaudio store
Does anyone has the BOM list of this version?
What should be the correct position of 2SK170/2SJ74 and ZTX450/ZTX550?
Thanks in advance
Alex
Click to expand...

Alex, the Bill of Materials is on the store page for the F5T boards. If you scroll down the page you will see it under the heading Helpful Links. There are 2 BOMs depending on if you are building V2 or V3
 
#4,580
Hi,
My plan is to use 32V rails.
Does anyone have any (constructive ;-) ) negative comments about these PSU capacitors

CORNELL DUBILIER SLPX223M050H9P3 Electrolytic Capacitor, Snap-in, 22000 µF, 50 V, SLPX Series, ± 20%,

(I'm only asking because their price point is very much lower than Vishay etc)
Thanks
 
You must log in or register to reply here.
Top Bottom