F4 power amplifier

[Studley]

In the user manual it says the F4 will work well with a preamp or other line source (assuming you have efficient speakers).

I'm wondering whether this would work: My CDP (ouput 2v) into a passive volume control (eg TVC or Lightspeed) into F4 driving Bastani Atlas open baffles (sensitivity 100db / 16 ohm load). A couple of watts is apparently enough to drive these OBs.

If necessary maybe I could insert a Burson Buffer in the chain as they add 6db.

??

[R-K Rønningstad]

Originally posted by Studley
In the user manual it says the F4 will work well with a preamp or other line source (assuming you have efficient speakers).

I'm wondering whether this would work: My CDP (ouput 2v) into a passive volume control (eg TVC or Lightspeed) into F4 driving Bastani Atlas open baffles (sensitivity 100db / 16 ohm load). A couple of watts is apparently enough to drive these OBs.

If necessary maybe I could insert a Burson Buffer in the chain as they add 6db.

??

As the F4 is unity gain, your 2 Volts (peak) will give 1/8 Watt RMS into your 16 ohms speaker. (P =U^2/2*R)

RK

[Studley]

RK
OK thanks (for showing my ignorance )

[spencer]

I have finished my second F4 amp today. Distortions as below:

Left: 0.016% @ 1W and 0.03% @5W
Right: 0.017% @ 1W and 0.035% @ 5W
All 1kHz, 8.2 ohm load. Bias 1.5A each channel.

I used it as balance mode and the bass is much firm and strong than single unit guess due to higher power and match up with my Bal DAC. I would say it is another step better!

Thanks NP for sharing this wonderful design.

Spencer

[protos]

Originally posted by lykkedk


This was from a very old thread, posted by master Pass himself... I guess it's allright that they grow hot!

Jesper.

Don´t forget that is amps at the primary not the total bias+losses of the amp itself at the secondary.

[Salas]

Its amazing how the old and straightforward buffer concept is celebrated worldwide, only after Nelson put it forward again. It seems that audio world is not needing super circuits, it simply needs concept lead.
Bravo Nelson.

[korben69]

Great job Spencer, very attractive babies, congratulations !
Could you let us know about your enclosures, seems to be galaxy...
Thanks for the answer.
Very good looking F4 pieces, I hope to design mine as successfully as yours.

[spencer]

The enclosure has two version but my final version is 200mm height x 400mm deep x 350mm wide because I manage to find a supplier of heatsink of 400mm wide x 50mm thick in China. I design the case with all drawings and ask a metal shop to custom made for me for a total cost about US$200/ea. Face plate is 10mm wider/taller with 10mm thick and all polished and anodized per my spec. All the plates and heat sink are connected together with 12 pieces "L" sharp bar with either holes or tapped holes. Total weight of the case is 13kg net and completed amp is over 20kg.

With this size, the temperature rise is about 18 deg C max.

[Nelson Pass]

Originally posted by salas
Its amazing how the old and straightforward buffer concept is celebrated worldwide, only after Nelson put it forward again.

Well, it just goes to show that this is a fashion industry.

[Variac]

Or it's because sometimes a new need arises which can be addressed by an old idea...