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Old 2nd August 2007, 06:25 PM   #991
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Default F1 vs F2 vs F3 vs F4

This is the post comparing the F1-F2-F3-F4 amps:

http://www.diyaudio.com/forums/showt...46#post1152546

Quote:

The F4 sounds like a cross between the F1 and the F3. Cleaner than the F2, a touch of sweetness, but the truth is still front and center. I have not heard this amp in my system (yet), so my thoughts about this may change. It is a very exciting product.
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Old 2nd August 2007, 06:29 PM   #992
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Default F1 vs F4 Bass

Quote:
I use the F1 for basses (20hz - 630hz). I'm happy (very) with it only that in some instances in somehow lacks the power for the woofer. I'm considering changing for the F4. Since you have listened both amps, what are the main differences between both F1 & F4 listening wise ?
Hi Nicola:

An impossible question. Because the F1 is a current source, and the F4 is a voltage source, a bass system designed for the F1 would not work well with the F4, and one that works well with the F4 would not work will with the F1.

That being said, both have worked very well in bass note reproduction when used with an appropriate speaker. The F1, because of its lower power, would work best with hi-efficiency woofers. If you are having a power shortage, I would certainly consider using the F4 in bridged mode where you can get a up to 100 watts of power.
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Old 6th August 2007, 11:48 AM   #993
spencer is offline spencer  Hong Kong
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F4 going to finish and now under bias adjust.....
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Old 6th August 2007, 11:51 AM   #994
spencer is offline spencer  Hong Kong
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Bias total 1.5A per channel and take very long time to become stable. DC offset below 5mV for all channel. Supply voltege at +22/-22V by using two 18Vx2 250VA transformers.
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Old 6th August 2007, 01:18 PM   #995
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Quote:
Originally posted by spencer
F4 going to finish and now under bias adjust.....
Good to see another F4 coming to life...very nice work Spencer


Those PCB are from PD?

Lets hear your first impressions of sound
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Old 6th August 2007, 06:15 PM   #996
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Default Re: F1 vs F4 Bass

[QUOTE]Originally posted by twitchie
[B]This is the post comparing the F1-F2-F3-F4 amps:

http://www.diyaudio.com/forums/showt...46#post1152546
Quote:
Originally posted by Jon Ver Halen


Hi Nicola:

An impossible question. Because the F1 is a current source, and the F4 is a voltage source, a bass system designed for the F1 would not work well with the F4, and one that works well with the F4 would not work will with the F1.

That being said, both have worked very well in bass note reproduction when used with an appropriate speaker. The F1, because of its lower power, would work best with hi-efficiency woofers. If you are having a power shortage, I would certainly consider using the F4 in bridged mode where you can get a up to 100 watts of power.

Many thanks for the comment. This is exactly what i'm trying to find out. The woofers are around 99db, but if I compare the F1 with a classical voltage 20 or 40w class A amps, with some instruments it seems to lack the headroom, like there is a more limited power available especially with chords / piano / cello - where the instrument is fast in its attack. But on the other side none of the voltage amps have this control... so as you wrote it is like strawberry or vanila... Kind regards

Specs from woofer are
SPL: 99dB enclosed in box reaches 105db 1m / 1w +- 2bd
Fc: 43 Hz (Qes: 0,34, Qts: 0,33, Qms: 10,5, VAS: 231, Re: 4,8 Ohm ,EPB: 126,5)
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Old 7th August 2007, 02:19 PM   #997
vizion is offline vizion  United States
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Can the F4 be driven with 2.8vrms from a source unit ?
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Old 7th August 2007, 02:22 PM   #998
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yeah I was wondering something of the same sort will a preamp with an 18.5 db gain be enough for the F4?
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Old 7th August 2007, 02:41 PM   #999
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Old 7th August 2007, 02:57 PM   #1000
Magura is offline Magura  Denmark
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Quote:
Originally posted by mpmarino

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