Wattage of Pass F5

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If you want more power look at the F5-Turbo..
Really? Where can I find out more about that?
Increasing MOS-FETs on their own will not increase power output..
I don't know. what's your output impeadance?
In order to increase power you do need more output devices...
Wait a minute! which is it, more output devices or not? Did you work for the government, or maybe the military previously?
...but that enables you to increase the power supply rails without stressing the MOS-FETs...
maybe just more current and not more voltage might not stress the FETs to much?
If you want more power - look at the Aleph 4, it is 100W/Channel in Class A.
Can you really take advantage of 100W/ch classA?
 
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No you are NOT driving each driver at half the power.

Each driver is working within its own frequency band.

Both drivers are being driven fully.

It's over simplistic to say that the BASS is working at 25W throughout its audio range and the TWEETER is working at 25W throughout its range but that is what the set-up is capable of.

In reality the tweeter has less work to do and does get fed with less power .

Agreed, both the drivers are not working at half the power.

But at the same time an extra amp is going to supplement the speaker.

Also agreed that tweeter + midrange power drawn will be less than the bass driver. The point I am trying to make is there is help from an extra amp.

I dont understand the volts, gain. Can you look at my preamp specs, is it suitable for f5
Thanks
pandu
 
Really? Where can I find out more about that?

I don't know. what's your output impeadance?

Wait a minute! which is it, more output devices or not? Did you work for the government, or maybe the military previously?

maybe just more current and not more voltage might not stress the FETs to much?

Can you really take advantage of 100W/ch classA?

I was over simplyfying a complex problem.
 
Please read the full thread.

YES, I do enjoy my music comfortably loud. Not excessively loud but I get no clipping with a nice 6W RMS background.

As AndrewT states, even at that modest volume, musical peaks will exceed 600W.

The Aleph 4 is a brilliant amplifier, easy to build and very easy on the ears.

I sold my Mark Levinson 60W/Ch Class A because it was "Horrible" in comparison.
 
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From your questions and your replies and your statements, I can read that you do not know the basics.

Knowing or not knowing basics is subjective. Depends on how we take it.
I definately agree that I am not an expert in that area.

I studied currrent electricity in college I*I*RT is power output by a resistor. With regard to electronics may not know much about it.

SOrry for bothering you.

Thanks
Pandu
 
The F5 is truly lovely at LOW volume with VERY EFFICIENT speakers.

At 25W it will clip early into the program at anything about COMFORTABLY LOUD.

Your Pre should be fine.

A lot of us, me included, are driving Alephs with low gain pre-amps. Relying on the high 2V ouput of current CD players.

Apolgies to the vinyl players out there.
 
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I'm not familiar with that notation.

However, most of the lesser Pass amps will run in Class A to a certain point and then continue on in Class A/B.
Zen1,2,3,4???? Zen5? Maybe I should go look. Zen 6,7?? Zen 8,9 Well you could argue the Aleph...F1,2??. F3, and ZV9. F4 hey! Bingo! an amp that goes to classB operation!!! F5 And another!!!
He must have been thinking Pass Labs :confused:
 
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The Aleph 4 runs at Class A up to 100W

If you do a bit of homework you will see that, in order to achieve concert performance, you would need impossibly high power outputs.

For true Opera Nirvana you might need over 10kW if not more.

The Aleph 4 probably runs into Class AB at over 100W but boy, that's better than 25W

The Aleph 4, in my opinion is Musical Nirvana. Beats the ML and Krell 250 - but that's my choice.
 
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TBPO the only real cost differences between building the smaller Pass amps is the number of MOS-FETs, the amount of heatsinking and the Power Supply.

Matching MOS-FETs isn't beyond the DIYer. I bought 50 to get the 24 that I needed.

The transformers and the big PSU caps are comparable in cost between the various amps.

If you hunt E-Bay you can get the heatsinks cheap. I paid £40 for the whole lot for mine.
 
It is 25 watts max per channel into 8 ohms. Does it mean that x watts in A and 25-x in B mode. What is the x when bias is set at 900mA.

What happens when we double the mosfets as recommended in the second design.

Let me know.

Thanks
Pandu

I think the original question was not quite answered.

When the bias is reduced, the heat is reduced at quiescent.

When you double the output mosfets the quiescent current is increased, so that the amp can remain in Class A for lower Z loads. The output power remains the same.
 
No, if the bias point (voltage) per mosfet is the SAME, then the quiescent current through the pair is DOUBLED.

You have TWICE the dissipation, not half.
One does not (in the F5) use a pair of mosfets per rail and then decrease the standing current usually. Kinda defeats the point.

The limit of the Low Z load is according to doubling the current. Assuming you want to remain in class A, etc...

_-_-bear
 
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Aleph 4 is not for me for now. It is too huge. My DIY capabilities are at a minimum. And also with respect to my room and speakers

The following specifications were pulled from B&K ref30 preamp.

Output Impedance: 221 Ohms
Input Impedance: 50 k Ohms
Signal to Noise Ratio: 98 dB CCIR 2 k Weighted
Maximum Output Level: 3 V rms
Input Sensitivity: 2 V in, 1.5 V reference out
Noise Test Reference Level: 46 mV

Does F5 suite above specifications

My speakers are Paradigm signature S4. It is 3 way bigger bookshelf.
Do you think 25W is enough to drive speakers whose efficiency is 90db and nominal impedence is 8 ohms. My paradigms are bi ampable. Is it better to use two channels to drive single speaker Meaning two stereo amps driving two speakers. Then I would be powering each speaker with 50 W capability instead of 25 W.



Thanks
Pandu
Regarding the B&K Ref 30, I believe the 3V max output is a B&K OM typo, and it is actually 9Vrms max (AD712 running on +/-15V rails), just like all the other B&K preamps of this vintage that I've seen...
 
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