An illustrated guide to building an F5

[Ben Mah]

The light bulb test is probably a false positive. The light bulb glows brightly at a high current. If you have set the bias up properly, that current draw is high enough to light the bulb up. The light bulb test only works when then bias is set to a smaller amount.

If the boards were set to their proper bias successfully and ran with no issue for hours, they should be okay.

If you are still worried, you can turn the pots back to the start and check with the lightbulb again.

 

[camarillo]

Tuesday Morning

I assembled everything together and ran a dim bulb test.

Failure.

So I then tested the PSU. That works.

Then the right channel by itself. Failure.

Left channel by itself. Failure.

I've checked all my connections.

I checked the mosfets for a ground issue. Nothing.

All the LEDs light up.

Appreciate any ideas.

 

[camarillo]

Maybe I missed something.
Why is the resistance value of R3 and R4 10k ohm instead of 10 ohm as in the original diagram?

 

[Dennis Hui]

Good catch! Those definitely should be 10 ohms.

@Chiptech: I think you need to change R3 and R4 to the proper value. Unfortunately you'll need to reset P1 and P2 to min value before powering up and biasing again.

 

[twastard]

page 167

 

[Chiptech]

The light bulb test is probably a false positive. The light bulb glows brightly at a high current. If you have set the bias up properly, that current draw is high enough to light the bulb up. The light bulb test only works when then bias is set to a smaller amount.

If the boards were set to their proper bias successfully and ran with no issue for hours, they should be okay.

If you are still worried, you can turn the pots back to the start and check with the lightbulb again.

Ok. I was hoping that was the issue. Yes both sides were working before I reassembled everything.

 

[Ben Mah]

You still need to fix R3 and R4.

 

[Chiptech]

Good catch! Those definitely should be 10 ohms.

@Chiptech: I think you need to change R3 and R4 to the proper value. Unfortunately you'll need to reset P1 and P2 to min value before powering up and biasing again.

I see what I did. I wanted to up the resistors to 2W, but ordered the wrong one.

Thanks to camarillo for sorting this out.

I will replace them, reset P1 & P2 and redo the biasing.

I should be a pro at this when i get done.

 

[Chiptech]

Yep.

 

[Chiptech]

I'm back.

Everything is working.

Both channels biased.

Now I have the unit put together and tomorrow I will bias with the lid on.

Close.

 

[Ben Mah]

Great news!

 

[Dennis Hui]

Yes. Good luck tomorrow.

 

[6L6]

Absolutely fantastic!!!!!

 

[Chiptech]

It works.

Sounds great after hour two.

No hum, silent.

I want to thank everyone who hung in there with me and ensured I crossed the finish line. I can't say enough about all of the great help and patience.

I'm going back to listening to music.

 

[6L6]

That is the best news I've heard in a couple of weeks!

Congratulations!!

 

[Dennis Hui]

That is wonderful news! Very happy to hear your perseverance has paid off.
Enjoy your new amp!

 

[ItsAllInMyHead]

Congratulations!!!!!

 

[Eric]

Score! I was pretty confident you'd get it sorted out!

 

[chiily]

It works.



Sounds great after hour two.



No hum, silent.



I want to thank everyone who hung in there with me and ensured I crossed the finish line. I can't say enough about all of the great help and patience.



I'm going back to listening to music.

Well done you, congratulations...enjoy

 

[Chiptech]

Connecting a REL sub to the F5

One week and going strong. I'm going to check the measurements later today.

I just got a REL sub and see attached for their recommended hook up to an amplifier.

I assume it will work fine with F5, but wanted to get some review on their approach.

I don't want to mess up my baby.

Thanks