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Old 4th July 2007, 07:55 AM   #881
nonoise is offline nonoise  South Africa
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Sorry to ask again but could anybody (hopefully Nelson)
answer the question regarding the Fairchild mosfets.
The reason I'am so insistent is that the Fairchild parts are 40% cheaper.

I dont want to sacrifice performance but my budget is limited
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Old 4th July 2007, 08:01 AM   #882
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Quote:
Originally posted by Zen Mod
old booster amps from toob era.......... for theaters ,but later also for cutters ..............even if they mostly have some gain..........

I was thinking of amps like Quad 405 and Stasis as they had one hi-q amp providing clean sound and one powerful providing the muscle (current), at least the ads said so, I seem to remember.

That is not to say I have anything against either of these amps, including the F4 (which I have not listened to either). The F4 seems in my opinion as a splendid idea, reducing the number of electronic components providing high enough swing from the source/preamplifier.

RK
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Old 4th July 2007, 05:06 PM   #883
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Quote:
Originally posted by nonoise
Sorry to ask again but could anybody (hopefully Nelson)
answer the question regarding the Fairchild mosfets.
The reason I'am so insistent is that the Fairchild parts are 40% cheaper.
The Fairchilds work fine. They have a slightly higher Vgs and
the distortion of the P channel devices is a bit lower, although
not enough to rule out the IR parts as followers.

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Old 4th July 2007, 06:41 PM   #884
nonoise is offline nonoise  South Africa
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Thank you very much Mr Pass I really appreciate you dedication and generosity.
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Old 6th July 2007, 02:05 PM   #885
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Default Plitron group buy

I posted some information on a possible Plitron group buy in the Group Buy forum. Just wanted to let people know since the F4 can use the model in the GB:

http://www.diyaudio.com/forums/showt...07#post1250007
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Old 9th July 2007, 03:17 PM   #886
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Default Re: F4 power amplifier

Quote:
Originally posted by Nelson Pass
www.passlabs.com/np/F4 Power Amplifier.pdf

The F4 is Class A impedance converting amplifier, having no voltage gain or feedback. Its input impedance is 48,000 ohms, and its output impedance is about 0.2 ohms. It is suitable for driving a high sensitivity loudspeaker with the output
voltage of a preamp or other line-level audio source.

Voltage Gain -0.5 dB

Few questions
Is it possible to drive this amps from a cross over with a output of 2.50 V at 600 ohms and loudspeakers of 100 db ?
Are the 60uV noise heard on 100 db speakers and would require a LPAD ?
Has the amps a thump on at the start like the F1 ?

Regards
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Old 9th July 2007, 04:26 PM   #887
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Quote:
Originally posted by Nicola
600 ohms and loudspeakers of 100 db
Sounds more like a headphone !
100dB/W or 100dB/mW ?

For a headphone with a 100dB/mW sensitivity: 60 x 10-6 Volts gives a soundpressure level of <18dB.
18dB is very soft.
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Old 9th July 2007, 06:04 PM   #888
nonoise is offline nonoise  South Africa
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jaco
I think Nicola meant that the active crossover were able to provide
2.50 V (probably RMS) into a 600 ohms load.
600 ohm is often specified as the terminating impedance
for pro-audio equipment. (This is as a result of often using transformers for coupling this type of equipment together)
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Old 9th July 2007, 06:17 PM   #889
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Default Re: Re: F4 power amplifier

Quote:
Originally posted by Nicola


Few questions
Is it possible to drive this amps from a cross over with a output of 2.50 V at 600 ohms and loudspeakers of 100 db ?
Are the 60uV noise heard on 100 db speakers and would require a LPAD ?
Has the amps a thump on at the start like the F1 ?

Regards
Yes, No, and No.

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Old 9th July 2007, 09:19 PM   #890
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I'm having problems with my LM431/TL431/KA431 SPICE model. Anyone have a version that I can try?

I use the Berkeley language (with b2spice).

Thanks.
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