Does Bi-Amping with F5 for the lows and AlephJ for mid/high make sense? - Page 3 - diyAudio
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Old 29th March 2013, 09:11 PM   #21
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I have taken many paths to come to this conclusion. In stead of telling me I am in the wrong forum, you might have asked me how I came to think so.
An FFT of my life would show a couple of peaks and some low level harmonics, but mainly random noise.
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Old 29th March 2013, 10:45 PM   #22
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Some speakers have dual binding posts on the back with a jumper for single amplifier use. Remove the jumper, and you can use two amps.

As far as modifying an existing speaker without dual binding posts, and that uses a parallel xover, I see no reason not to do that.

Different sensitivity drivers, different gain amps? That is what pads on the output of the amp, at the driver or at the input of the amp are for.
Or - may be used for.

Active crossovers before an amp may or may not have better fidelity. Implementation is critical. Cheaper and more sure is passive.

A simple HP (cap) at the input of a SS amp that is used for HF in a biamp situation is not a bad idea as long as the F3 point is somewhat below the F3 point of the exisiting xover. ie. get rid of the LF stuff, don't effect the existing xover point/slope.

Regardless, it is difficult to "gild" an average speaker by biamping. But it may well be possible to get a better subjective result with a higher or lower DF amp on the bottom end (depending on what is needed) and a "smoother" sounding amp on the top end. Something like a SE triode amp often does sound much "kinder" heard on the tweeters of typical speakers, but won't do the job full range.

The F5, in my experience, is capable when implemented cleverly of being a fantastic amp for the high frequencies. But the F5 does seem to vary all over the map depending on parts and implementation details. Not the least of which is the very real possibility of having fake JFets for the input to alter the results.

My 2 cents... doesn't even get you a bubble gum any longer.
_-_-bear -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ]
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Old 6th May 2013, 01:00 PM   #23
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YESSSSS it does make sense!
Tried it this weekend. Had the AlephJ with single MosFets for highs and the F5 for the lows. Sounded amazing!!!!! :-D
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Old 8th May 2013, 08:50 PM   #24
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I agree with Vacufile...a passive line level cross over before the amps is the way to go...dividing the voltage and current at line level is easier to can use very high quality capacitors and coils at one volt that would be very expensive when sized for 30 volts and more current.
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Old 9th May 2013, 01:54 PM   #25
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Step by step...
Next step ofcourse will be to make active filters
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Old 9th May 2013, 02:37 PM   #26
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I made my filters passive...coils and capacitors...I used headers so I could switch in and out capacitors of different values. The coils were easy to wind and inductance can be made to vary with a movable core.

I tuned the filters by getting the slopes approximately correct in a simulator...then I sweep the real thing with a signal generator and adjust the slopes to where they need to be. Works cheap and I think better than op amp based active filters. B1 buffers can be used to good effect. BOSOZ makes a good front end for an analog filter because you can vary the output level of a BOSOZ with out changing the out put impedance and upsetting the filter.
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Old 21st September 2013, 03:16 PM   #27
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The problem I have with either way of biamping the speaker is when the crossover sits a bit higher, say, 200-500hz cross point. This is a critical region that if one does not have extremely identical amplifiers, will easily hear a difference between the one running the top section and the one running the lower section. This said, if one is able to integrate two amplifiers properly via either bi-amping w/active crossover or just using the biamp capable speaker terminals, there is a ton to be gained.

What is the crossover point in the speakers that people are biamping with and do you not hear a difference that does not sound "off" by using two different sounding amplifiers? I know it is very possible to make work, but when you have such an outstanding amplifier that does it all so well, it begs to ask what exactly are you willing to give up just to gain a bit more headroom/bandwidth/dynamic control/etc.
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Old 21st September 2013, 03:36 PM   #28
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I'm trying an Aleph4 with mids and F5 with tweeters. The sub 400Hz is being dealt with by a different genre of amp. What it will perform like I don't know.

The mid range contains the most detail which is why I've given it to the most able amplifier.
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Old 21st September 2013, 03:48 PM   #29
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Default Bi-amping

I am building in a two-stage approach.

Stage 1: Use my Pass Aleph 5 for mid and high and a Crown K2 for bass
Stage 2: When the F5 project is finished , replace the Aleph 5 with F5

I am modifying the crossover cards in my JBL crossover unit to be compatible with my 4343s.. that is still to be done .. Stage 0 I guess.

Stage 3: Under discussion. Sell the Aleph 5 and its pre-amp and start all over again.. not making the mistakes that I have made / expect to make

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Old 21st September 2013, 03:53 PM   #30
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The F5 is a bit light for bass use, at only 25W an F5 turbo would be better.

I've got a Dr White 150W for bass duties. Aleph 4 (100W) for mids and F5 (25W) for highs.
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