F4 power amplifier

[Zen Mod]

Originally posted by jacco vermeulen


That does it, i'm a drooling mental retard.

..................

welcome to the club

[Magura]

At 91.5db/w it seems I have to repeat myself, something isn't right if 25W can't deliver the goods! Most likely as somebody suggested, the pre isn't up to the job.

Magura

[analogair]

Actually the MF A1 has specs that says 2 x 20W into 8 ohm Class A, but im sertain they only go about 8-10W in Class A...

The Audiovector 4 have been put away in my basement and have been replaced with a pair of B&W Matrix 801 Series 2

I know they should be rated as having a sencitivity at 96dB/1m/ 8w

I somehow am pretty sure that the are harder to drive than that, so if someone have some real life specs on my new used babys.

But i can actually turn the knob almost to 11 o'clock before the sound turns muddy and uncomfortable.

Just before that it is actually pretty loud, but not as loud as i would like it to be for some sorts of music (read.. Roger Waters, Dire Straits, Thin Lizzy, Midnight Oil, Queen...etc...)

[lykkedk]

have you headphone output on your CD player?

try to feed Babelfish from that output,just for test.....then tell us what you hear.

I just tried that Look's like we have a winner here !

The soundpressure, is louder now, maybe 3/5 maybe even a little more !!! Of what the speaker's usually are playing when driving near to the max, with my leachamp. So i guess Magura is right when telling me, that the preamp is the problem.

[Zen Mod]

Originally posted by lykkedk


I just tried that Look's like we have a winner here !

The soundpressure, is louder now, maybe 3/5 maybe even a little more !!! Of what the speaker's usually are playing when driving near to the max, with my leachamp. So i guess Magura is right when telling me, that the preamp is the problem.

correction:

"So i guess steen is right when telling me, that the preamp is the problem


anyway-change the spks

[doggy]

I am attempting to build the F4 point to point. Waiting for parts from tech diy, the rest I sourced from digikey. Has anyone compared the A30 to the F4, and what would the differences be? I would assume less gain with the F4; and perhaps more transparency? With my fostex fe108ez-mcm 8"combo horn I have lots of power with the A30 and very enjoyable.

[massimo]

Steenoe, you probably skipped my post #456 on this thread (page 46) and my offer. That is still valid, if you want to try.

[lykkedk]

I was wondering about this note, from the f4 power amp papers (not rev0).

Notes:
Output device bias is approximately .53 amps per device, which measures 0.25
volts across the .47 ohm source resistors.

Is this true, has any of you meassured ?, because it aint much right ?

Jesper

[cviller]

Originally posted by lykkedk
I was wondering about this note, from the f4 power amp papers (not rev0).

Is this true, has any of you meassured ?, because it aint much right ?

Jesper

This thread is becoming so long it repeats itself...
You'll find the answer here and a few posts later when steen finishes his amp.
http://www.diyaudio.com/forums/showt...23#post1169323

[lykkedk]

Actually i was looking at youre post,but it doesent come clear to me, how much current / voltage each mosfet must swallow

I am just preparing a setup for matching mosfets... Se this LINK

So i would just like to know the voltage / current, for correct matching. (And to test the heatdissapation too)

Jesper