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Old 24th March 2010, 06:29 PM   #7521
EUVL is offline EUVL  Europe
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Not always.
And it also depends on how you define close.

Patrick
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Old 25th March 2010, 02:11 PM   #7522
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Originally Posted by bobodioulasso View Post
Massimo,
it looks like a bad solder joint.
It seems you were right, the soldering appeared all good but...

Last time I checked, I got V+ on P-ch mosfet source with pots at zero. Bending lightly the board I got zero or V+ as an intermittent contact was in action.
I've decided to populate a new board (I took a couple for spare and was a good choice at this point) so I desoldered all the components from the "faulty" one. The mosfets seem to work correctly at least with the test alazira mentioned earlier (same procedure can be found at Basic Testing of Semiconductor Devices).
The bare "faulty" board shows a very difficult continuity between both mosfet source and their relative resistor (R11/R12). Could it be the problem?
The other twin mono still works perfectly stable.

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Originally Posted by bear View Post
...............................This is assuming that something else isn't a wrong value or miswired or otherwise malfunctioning...
Your final words were profetic
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Old 25th March 2010, 10:03 PM   #7523
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I'm thinking about building two F5's, a total of four channels, to bi-amp my speakers. How I'd like to biamp them is just tie the two inputs of each amplifier together with a single RCA connector. This would mean that I would only have a single interconnect going to each amp but dual speaker cables going to the bass/treble connectors of my two-way speakers. Referring to the original schematic in post #89 I'm wondering if I'd have to change the values of R9 or R10 to prevent my preamp from seeing half the input impedance it normally would on a power amp. Suggestions anyone?

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Dan
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Old 25th March 2010, 10:07 PM   #7524
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Usually a pre amp out is much lower impedance than the input of a power amp.

My preamp is about 100ohms output impedance and the power amp is 47K input impedance so nothing to worry about there.
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Old 25th March 2010, 11:19 PM   #7525
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Quote:
Originally Posted by dantwomey View Post
I'm thinking about building two F5's, a total of four channels, to bi-amp my speakers...

Dan
Don't you think a filter between preamp and amps would be a better way?
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Old 25th March 2010, 11:28 PM   #7526
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Fore biamp I would consider a preamp with double preamp modules
The one for woofer amp would have more gain, and additional attenuator

Or just additional preamp module for woofer amp
There are a few with adjustable gain
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Old 26th March 2010, 12:36 AM   #7527
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one could tweak the gain at the amp level by adjusting R6 and R7 a bit. probably better to do so on a bass amp side as to not muck up house F5 clone sound.
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Old 26th March 2010, 01:13 AM   #7528
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Originally Posted by Tea-Bag View Post
one could tweak the gain at the amp level by adjusting R6 and R7 a bit. probably better to do so on a bass amp side as to not muck up house F5 clone sound.
If 'Father Pass' and others give my idea a thumbs down then I'll probably go the traditional route with monoblocks.

Regards,
Dan
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Old 26th March 2010, 01:51 AM   #7529
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Biamping a passive speaker doesnt automatically lead to better sound
I have had no luck with that
Others will say they have
My guess is that it very much depends on the actual speaker, and how its done

But it could be a step on the way to making an active speaker with DSP
But again, I might consider combining F5 with a different kind of amp for the lows

I think a pair of F5 monos would be a good choise fore further devellopments

If you insist on two F5 stereo amps, I would suggest one as pr original F5 with single pair output devices
And the other with double pairs
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Old 26th March 2010, 02:16 AM   #7530
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F5 is 10dB lower gain than a typical power amp - I'd put the attenuator on the woofer side, unless you have 10dB more efficient (sensitive) tweeters... do the math first...

I'd buffer a second output for the woofer, but all buffers do not sound the same... I've yet to find a transparent DSP, but it would be nice...

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