The diyAudio Firstwatt F6

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#583
6L6 said:
Had to use WW -- it's the only thing available in such an odd value.
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wdecho said:
So you would use a wire wound resistor. I had a mindset of metal oxide and did not consider wire wound.
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I was making a bom with only ww resistors when I came across these posts. So do you suggest to pick ROX or RNX Vishay resistors rather than RN60 when possible? Even though they're quite pricey and with higher power values?
 
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#584
No. The RN55 and RN60 resistors are my favorite resistors more than all others.

The 3W Panasonic ERX, ERG are wonderful.

Again, the reason for the WW was because Nelson specified a 0.56ohm 3W in that position.

All that said, resistors don't make very much difference in the sound quality.
 
#586
A personal review of the F6 amplifier which could be the complete opposite of someone else's. This is the 3rd Pass amplifier I have built starting with the Aleph 30, (with some of the best top end I have heard), a single ended BA3 with 3 pair of outputs, and now the F6. Any amplifier sound is different depending on the speakers used. That is why Mr Pass sells different flavours of amplifiers. My speakers are very efficient modified Klipsch LaScalla's so with anyone else's speakers the sound will be different. With my horns the BA3 is a wonderful amp with a smooth midrange and good soundstage. One I could be very happy with. I A B'd the BA3 for the F6 multiple times to get an idea on the difference's in the sound. I do not have a SP meter so my analyses is purely amateurs' by what my ears hear. I tried to adjust each amplifier so that the volume was the same from both amplifiers. By the way, I am using the front end of the BA3 as a preamp in it's own enclosure. To my ears, the difference in the sound was the F6 showed more detail with a better bottom end and does have a significant better sound stage. It is just a tad bright with the Lascalla's but I was expecting that, nothing that is annoying at normal listening levels but remember this is with horn speakers. With a good vinyl recording the sound was better than I can ever remember but with a pressing that is not as good or recorded very well the sound was worse than the SE BA3. Most everything with the SE BA3 sounded good. I Contribute this to better detail than any amplifier I have heard in my system. The F6 will show any fault in the recording. All 3 of my Pass amplifiers had better bass than I have ever heard on my speakers. Ever since I bought these speakers in '86 the general consensus is that Lascalla's are lacking in bass. Not so with these Pass amps. A lot of the best sounding bass I have ever heard from my speakers. I have a very good sub but most of the time I do not use it, it is just not necessary and when I do use the sub it is very little with a sharp cutoff just to get some more low at the very bottom end. I have run my speakers with amplifiers with 200 watts per channel never knowing that what I needed was a good Pass amp with 25 watts. With good source material the F6 is a sweet amplifier. The old saying apply's, crap in crap out. It has pinpoint positioning of the singer that does not waver from center with every instrument in it's place.

All this observation depends on how your amplifier is built, of course, and the speakers you are using. I am enjoying my F6 very much.

David
 
#589
I found a solution for the tad of brightness I heard on my horn speakers. I cut the midrange back 2.4 db using my crossover autotransformer. Even more enjoyable now. I failed to mention that the SE Burning amp I built was the fastest sounding amp I had heard until this F6. It sounds to me even quicker and sharper. Reno Hi Fi, one of First Watts distributors, describe the sound as "The F6 has a glorious sound and similar to that of a PASS amp which costs more than twice as much! "
Reno Hi-Fi
Maybe the S-2 SIT ? Similar is what they say but do not say to what.
 
#590
wdecho said:
Reno Hi Fi, one of First Watts distributors, describe the sound as "The F6 has a glorious sound and similar to that of a PASS amp which costs more than twice as much! "
Reno Hi-Fi
Maybe the S-2 SIT ? Similar is what they say but do not say to what.
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Interesting...Mark did say a Pass amp, so perhaps he was thinking of something like the XA30.8?

I definitely need to try an F6.

Dennis
 
#592
+1

IMO it really is that good.

It's now had long sessions with all my hma full range speakers, fostex 167, 206, seas FA22 and MA alpair10.2 and also Lynn Olson Ariel 6. Finally it's had a long time on my full range ER audio electrostatics(ESL3s).

The main system is now squeezebox classic, F6 and ESL3s, and I'm sticking with it at the moment. I'm surprised it has such control of the electrostatics but it certainly seems to have.

If anybody is in doubt or sitting on the fence about building it I'd say 'do it'.

Ed
 
#597
Hello. I've had a trawl through this thread and the other F6 thread and I can't find an answer to my question. It is about the blue led.

In the document 'Nelson Pass talks at burning amp festival 2012', Nelson says the blue leds develop about 2.7v. Does this mean they have a forward voltage of 1.35v each? Does the inclusion of the pots mean the forward voltage value of the leds is not critical? If so, would another colour led do? And if not another colour, blue leds also come with different forward voltages. I'm just curious as to what the requirement is. Could this be a specific zener diode?

Sorry if this is a stupid query!
 
#598
The Led's on the amp using semisouth fets determine the bias but most people are building the IRFP240 one that is biased with Zener diodes so my understanding is that the led is just to show that the channel is on so it doesn't matter what led you use if you have the correct resistor. The Led may have some other function on the Mosfet version but I am not aware of it. The one NP is talking about at the 2012 festival was the semisouth one.
 
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