The F5X Preamp

[EUVL]

Now under thermal test.
Otherwise operational, bar some user interface cosmetics.




Patrick

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[BigE]

Wow!

This is more than DIY.... this is bespoke.

 

[EUVL]

I think you will like our F5X power amp as well ....




Patrick

 

[maxw]

How does the power switch work in both units? Is it soft on/off?

 

[EUVL]

There is no power switch at the PSU.
But one can be added at the mains plug if so wish.
The button at the front of the PSU switches off the regulator pass devices.
Thus cutting supply tothe amp.

There is of course build-in soft start, etc.


Patrick

 

[maxw]

The button at the front of the PSU switches off the regulator pass devices.

Interesting. What's the power consumption when powered "off"? If you have one of those measuring devices...

 

[EUVL]

For the amps zero. Off is off.

The auxiliaries consumes almost 10W.
Many relays. And the display eats a lot of current.
(No SMPS, all linear regulators)


Patrick

 

[merlin2069er]

Is this an improvement on the b1 / dcb1? how well does it match with an F5 amp?

 

[CeeVee]

Please do a little research...you will be grateful you did.

 

[merlin2069er]

Where do I get the boards and bom?

 

[Morde]

Here is the GB thread: Interest for Potential GB for F5X Preamp
Please check post #40 for schedule.

 

[phongnavy]

Can anyone share the F5X-Preamp BOM list for me? please! Many thank

 

[Nikon1975]

Slowly but steady:

PSU: Done
Output stage: Done
Input stage: Done
Volume control: Done
Software: Done

Now I need to mill the front panel and put the controller inside.

D.

 

[EUVL]

Patrick

 

[Nikon1975]

I am thinking about reducing the gain a bit. I get 10v out with 1V in. Probably an overkill.

D.

 

[EUVL]

You can try. Just watch stability.
And not for GB subscribers who are using laterals as power device.


Patrick

 

[Nikon1975]

Some more pictures of the creatures: the front panels are still to be done. These are temporary.

I included in the power supply outlets to power my monoblocks. There are 3 lemo cables between the psu and the pre: one for the power of each channels and one for the control voltages and relays.

 

[EUVL]

You have PM.


Patrick

 

[CeeVee]

Impressive work Nikon.

 

[EUVL]

F5X Pre with a Gain of 3 ?

There is a request for the preamp with less gain.

Normally I recommend that you do not use the attenuator at any level higher than -10dB.
So with a source output of 2Vrms per phase, you will have max input to the pre at +/-0.9V per phase.
With a gain of 3, you will just get back 2Vrms at the output.

This is fine for directly connection to the F5X power amp.
But if you have a power amp with higher rails, you might want more output.
Or you have an active crossover in between, you can easily lose 6 to 10 dB.
So do bear that in mind.

I've more or less worked out how to reduce gain to 3x in simulation.
But I want to have it tested before publication.
GB subscribers will have access to the spice files at the usual location.
Maybe in a few weeks' time.


Patrick