I feel that the M2 will disappoint like the F5 did because of my complex B&W speaker load.
I've got a pair of B&W 800D3s on order which will challenge these amplifiers even more.
I've got a pair of B&W 800D3s on order which will challenge these amplifiers even more.
In that case take a look here: F-5 Turbo boards
Another suggestion, a 100W Class AB amplifier inspired by Papa's F5 (there's an open GB going on): FSSA amplifier build thread with review
Another suggestion, a 100W Class AB amplifier inspired by Papa's F5 (there's an open GB going on): FSSA amplifier build thread with review
Last edited:
Maybe you are right, especially if one's dislike for the F5 is not about its power, but rather its sonic signature. Which seems to be the case here since KatieandDad prefered Aleph J over F5. And I would guess that Aleph J should have a harder time driving a difficult load!
+1
Max. power is just out thing. Looking at the impedance curve of the B&W 800 shows that you need an amplifier with low output impedance (=high damping factor). Since the impedance dips to 3 Ohm, you'll want high output current.
As I wrote before: crank up the bias current of your Aleph J!
You could also increase the negative feedback to further improve the damping factor.
Or you could just get some better speakers that are more suitable for your amps.
My speakers are a fairly constant 3 Ohms (Apogee Stage) all my Papa amps can drive them to uncomfortable levels.
That was the idea of planting the seed. I doesn't take a lot of imagination to arrive at a J2 with big boots.
Building blocks:
Cascoded AJ/J2 front end driving a current sourced emitter follower (see ZM's Babelfish ᄅſ for emitter follower).
BAF2015 Schade feedback amplifier, ditch the Shade feedback.
Connect the global feedback.
Give it a name - Leggo.
Job done.
Attachments
Last edited:
Hmm, I don't get it. Why do you need a J2 to run more current? The bias current can be just as much with the J as with the J2, if you ask me. It just depends on the heatsinks and the output devices.
Take that as the yard stick (or meter rule, whichever you prefer)
100W into 8 ohm is 28.3V rms at 3.53A, 5.77A at 3 ohm.
Supply rails will need to be around +-35V.
35V x 2A bias is 70W per device (upper and lower) at idle, a little too much for a single TO-247.
If you want to crank the bias to 3.5A, that would be 122.5W per device.
Big boots
That's probably as far as I'd take it, about a 1/3rd of the rated dissipation.
Member
Joined 2009
Paid Member
At some point it’s worth trying a high-quality class aB, you might be pleasantly surprised at how darn good it sounds especially if your only experience of such amplifiers have been Poorly designed and poorly constructed
Member
Joined 2009
Paid Member