F5 Turbo Circuit Boards

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#1,762
beetle said:
What do you think is the best? Low bias ~1-1.5A with 35V rails or high bias ~1.5-2A with 24V rails? Will bridge the F5t so the speakers will see double voltage any way. Will use 8 output devices per channel, F5 turbo V1. Will drive these speakers with it: Dynaudio Special Twenty-Five loudspeaker Measurements | Stereophile.com

Dissipation is already crazy with this.
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that depends on what you want the amp to do.
the higher bias, the higher classA power. lower the rails, lower the power will be.
the best way. amp wise., is 2+A bias with +/-40V rails. but that will cost you in regard to cooling. so ask yourself. how much power do you need. you are the only one that can answer that.
 
#1,763
beetle said:
What do you think is the best? Low bias ~1-1.5A with 35V rails or high bias ~1.5-2A with 24V rails? Will bridge the F5t so the speakers will see double voltage any way. Will use 8 output devices per channel, F5 turbo V1. Will drive these speakers with it: Dynaudio Special Twenty-Five loudspeaker Measurements | Stereophile.com

Dissipation is already crazy with this.
Click to expand...

well. just had a quick look at those speakers. first no,no in regards to class A is the 4ohm nominel. sec is the 89db at 2W so 86db at 1W.
if you want this to play in class A a good way up. it demands alot.
say +/-45 rails and around 2.6A bias. will give you 50W class A at 4ohm. and a dissipation of 234W pr ch. + losses in PSU.
 
#1,768
AudioSan said:
well. just had a quick look at those speakers. first no,no in regards to class A is the 4ohm nominel. sec is the 89db at 2W so 86db at 1W.
if you want this to play in class A a good way up. it demands alot.
say +/-45 rails and around 2.6A bias. will give you 50W class A at 4ohm. and a dissipation of 234W pr ch. + losses in PSU.
Click to expand...

In this case you recomend one pair of output devices. I am planing to bridge the amp, so I have a different case here. So the voltage the speaker is seeing is double. Therefor twice the wattage. So I think lowering the rail voltage is no problem her. Or is it? I am going to bridge it to have symmetrical inputs. Or is there anything wrong with my consideration?

Why 2 output devices and not 4?

45V Rails with 2.6A bias will be quite a bitch to keep cool. With 8 output devices each channel allmost 1kw of heat.
 
#1,769
so you planning on a balanced amp? then you can cut the rails in half🙂
but then agein. on 4ohm speakers? thats 2ohm pr amp.
the bias i'm talking about is total bias for all pairs.
but to run this at any high class A power will give you a headake and a electric bill thats off the roof🙂
 
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#1,770
Bias is not summing up when bridged, as far as I understand. Disipation will be this per channel: 2 F5t*2A Bias*24V*8 Output devices = 384W or 576W with 3A Bias.

I am thinking about using one Modushop 5U 500 case per channel. They tell one sink can handle 0.2C°/W. There are 4 of them per chassis. 2 output devices per sink. Makes 96W to 144W disipation for each sink. 19.2 to 28.8°C above ambient in best case.

I think 100W per sink should conservatively spoken be possible. Then let's see if the sink can handle more heat.

What do you think?


Maybe my GF will be off to the moon when I tell her about the consumption. She is allready suspicious about my gear. Maybe I get rid of the power-on LEDs soon. She thinks there are to many of them. No LED, no consumption. solved. 😀
 
#1,771
I was asked whether the new boards will fit the UMS, which is the drilled and tapped hole standard as used in the diyAudio chassis. The answer is YES! that's the point.

To see the standard, go to t he store here:
http://www.diyaudio.com/store/ or select it at t he top of this page,
then look for this link:

PCB Summary (all amplifier PCBs are UMS compliant)

the 400mm deep chassis has more holes , as listed in the Standard so will accommodate 2 boards on each side, with MOSFETS and diodes. Four MOSFETS and DIODE per side in other words. the 300mm deep chassis will accommodate one board per side, ie 2 MOSFETS and 2 DIODES per side

Alex has laid these out for us per Toecutter's design. He's amazing!

We hope that board makers for all projects will use this standard when possible to make building up amps a lot easier!
 
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#1,772
beetle said:
Bias is not summing up when bridged, as far as I understand. Disipation will be this per channel: 2 F5t*2A Bias*24V*8 Output devices = 384W or 576W with 3A Bias.

I am thinking about using one Modushop 5U 500 case per channel. They tell one sink can handle 0.2C°/W. There are 4 of them per chassis. 2 output devices per sink. Makes 96W to 144W disipation for each sink. 19.2 to 28.8°C above ambient in best case.

I think 100W per sink should conservatively spoken be possible. Then let's see if the sink can handle more heat.

What do you think?


Maybe my GF will be off to the moon when I tell her about the consumption. She is allready suspicious about my gear. Maybe I get rid of the power-on LEDs soon. She thinks there are to many of them. No LED, no consumption. solved. 😀
Click to expand...

they can handle a lot of heat those beasts. but at 2A bias. there is not much class A power when the amps sees 2ohm.
 
#1,779
So ~3A bias 24V rails then. I would assume that Modushop 5U 500 has not the right sinks for 576W per channel. Or does it?

1kva 18V toroid will be costly. Any good source in Europe?

I would expect a total power of up to 200W in 4 ohm Class B and 36W class A. Right?
 
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