f5- almost there
well I know you all cann't wait for today's installment-of
As the Amp Turns-
Got the resistors repositioned and that turns out to have been the issue with the big voltage on the speaker binding posts- thanks fran and peter-
Tell ya though, with the big leads of the mosfets and the power resistors going through tight little pads, desoldering( I have a real desoldering iron, no wick in this house) was not only a chore but ate up the pads pretty badly- YUCK-Fairly easy going in not so much coming out- turns out the resistors weren't in circuit after I tore up the pads desoldering and shazaam there is the return of my big voltage- I had to solder a bar across the bottom of the resistors and the output on just one board. I think the bridge will be fine- my beautiful PD bards now look like they were ravaged by a hot poker in the hands of my 15yr old. que sera-
Got to the balancing of the outputs and that seems to be going well- love having three functioning multimeters- brought the boards individually up to .59 vdc with 0dc at the speaker posts (on a 1 amp fast blow fuse!) and back down to.4 vdc for 1/2 hr for a little burn in and to check heat generation-
Thats a pleasant surprise; what I thought would be inadequate heat sinking seems to be doing well at this point-9.5 wide x 8.5 high by 1.5 deep- they are warm but not hot after 1/2hr- fans may not be that big a deal
On our next episode we'll see how they sound-
be patient gentle readers,
to all a good night!
rob
well I know you all cann't wait for today's installment-of
As the Amp Turns-
Got the resistors repositioned and that turns out to have been the issue with the big voltage on the speaker binding posts- thanks fran and peter-
Tell ya though, with the big leads of the mosfets and the power resistors going through tight little pads, desoldering( I have a real desoldering iron, no wick in this house) was not only a chore but ate up the pads pretty badly- YUCK-Fairly easy going in not so much coming out- turns out the resistors weren't in circuit after I tore up the pads desoldering and shazaam there is the return of my big voltage- I had to solder a bar across the bottom of the resistors and the output on just one board. I think the bridge will be fine- my beautiful PD bards now look like they were ravaged by a hot poker in the hands of my 15yr old. que sera-
Got to the balancing of the outputs and that seems to be going well- love having three functioning multimeters- brought the boards individually up to .59 vdc with 0dc at the speaker posts (on a 1 amp fast blow fuse!) and back down to.4 vdc for 1/2 hr for a little burn in and to check heat generation-
Thats a pleasant surprise; what I thought would be inadequate heat sinking seems to be doing well at this point-9.5 wide x 8.5 high by 1.5 deep- they are warm but not hot after 1/2hr- fans may not be that big a deal
On our next episode we'll see how they sound-
be patient gentle readers,
to all a good night!
rob
I am actually intending to drive just the mid and top with the F5 and use my aleph 5 s for the bass. I dont expect to run the 801's at full volume from two 25w channels. I was driving some bookshelf speakers when testing and the drivers are about the same size as the mid tops on the 801's ( yes I know size isnt the specific factor here) I dont think this is unrealistic.
dave
dave
labjr said:
Hmm... I dont think you really know what your talking about. Ive been running the 801s for about 4-5 years with the aleph 5s and they sound great. The addition of the F5s would lessen the loadon the A5s. Ive run these speakers with an Audiolab 8000A at 60wpc and they sounded great too.
The problem lies in the preamp that in single ended mode has around 12db of gain but 20bd in balanced. I have found some help here :
http://www.diyaudio.com/forums/showthread/t-101152-p-1.html
The solution is build the other two F5s I am planning and run them balanced. Then I'll need a splitter/buffer as I only have one set of balanced outs ( some sort of Bnumber thing I was hoping
) Running the two f5s unbalanced was a stopgap...Everytime I've ever heard the 801s they were driven with large 150-200 watt amplifiers. All the reviews I've read recommended a bare minimum of 100W. Thus, I can't see why you are surprised that the F5 is clipping at a low volume.
I don't see the point in trying to use a 25 watt amp for a relatively inefficient speaker. It's not even the minmimum recommended power for that speaker.
I don't see the point in trying to use a 25 watt amp for a relatively inefficient speaker. It's not even the minmimum recommended power for that speaker.
