I dont have a scope to check ( if thats what i need to check ? ) Resistors 11/12and 5-9get pretty hot along with q1/2
dhole said:
q1 an q2 should not get hot. Have you triple checked every component against the schematics?
Got it.... usuall stupidity.. I drilled some of the connections to fit my bigger wiring . You guessed it no connection between top and bottom plates. Ive done this before and had no problems , simple mistake to make...
thanks for the advise ! Just ignore me next time
dave
thanks for the advise ! Just ignore me next time
dave
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
Im up and running two channels of F5 now! hooray! Im driving them with an x-bosoz and I get clipping at what seems like quite a low volume. I have B&W Matrix 801 speakers. Any advice on tweaking or is this the volume I have to be happy with ?
dave
dave
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
dhole said:
The B&Ws need about with ten times the power of the F5 to sound good. I don't see how this will ever work well even with two amplifiers. Besides the Aleph 5 is only sixty watts.
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.
labjr said:
"Power Handling 50W – 300W into 8 ohms " 801 pdf
I am using the 25w for the mid and top and 60w for bass.
It dosent clip at 60w driving the whole speaker !
Can I put a y cable on the output of my amp and run two power amps or is this a dumb idea ? ( bring on the insults hehe)
dhole said:
ok - there it is :
>insult<
ya happy now ?
logical idea regarding Y cable ,even better to have two sets of outputs on preamp , along with attenuator for one set of outputs
bi-amplify in it's tradition meaning. Not as an active speaker system.
It's easiest if all the amps have exactly the same gain. Then no pots nor adjustments are necessary.
It's easiest if all the amps have exactly the same gain. Then no pots nor adjustments are necessary.
AndrewT said:
I think as stated earlier, and if I got Dhole's intentions right, balanced F5's on bottom would be 21db gain, 1 f5 on top would be 15db gain. So fiddlin may be needed.