F6 Illustrated Build Guide

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#281
heatsink dilemnas..

Now it gets interesting 🙂 Heat sinks And cases ?
Not really wanting to spend 350$ + cdn on a DIY shoppe case.
Easier though, also of a wee bit Pedestrian appearance imo 😱.
Certainly so after wading thru all the v nice to exquisite DIY build gallery photos.
Consequently I'm perusing Heatsink sources with evil intent.
Conrad.au seems ok, albeit somewhat size constrained,
however Shipping from the other side of the Planet adds complication.
HeatsinksUsa has basically One extrusion usable for the F6's 10" long pcbs..their 10.08" long one is 'just' usable.
Their other styles feature 1" long fins which seem as inadequate ?
Would there be heat flow Problems with vertically mounting the PCBs, logic suggests there would be... but ?

Considering a DIY Copper Heatsink lashup ..
Have ample supplies of such and it's allegedly far better at cooling than ali.
Easy(ish) and allows for more design freedom.. in theory at least.
Just a possibility... so far.
 
#283
JFets , even if they're burned , have no influence on output offset

check trimpots - best to remove mosfets from circuit and check can you set bias voltage for each mosfet in entire possible voltage range (0 to full LED voltage)

btw. for better sleep - pull JFets out and test them for Idss ; that way you'll know are they damaged in any way
 
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#284
Trimpots are checked. They're ok. I ll try best version. ( My zeners are 7.2v. so till 7.2v??)
Last edit: i have a couple idds 6.8 jfets is it suits?
Thanks.

SM-N910C cihazımdan Tapatalk kullanılarak gönderildi
 
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#287
Note to self...not discharging hefty power supply after testing will cause large flash when cutting V- & V+ leads.....😛 Stop building as tiredness sets in is the rule for me, along with cut one lead at the time......Good thing I wasnt disarming a bomb. No damage done. Should be doing final wiring and biasing up this evening.

Russellc
 
#291
WalterW said:
And your cutter is gone I guess...
Click to expand...

My favorite exolite now has a small notch in it that must be avoided to clip wires. Time for a new set...I really liked those.

Oh well, F-6 is all wired up now. since I assembled the boards way back when they and the transformers were first in the store, they have the old specified zener and resistors. Bias set to .530 both channels, 3 mV offset steady as a rock.

Tried them briefly with computer speakers and B-1, played music with no noise or hum. only odd note thus far is the LEDs, one just bearly has a glow in there, and the other is hardly any brighter.

Deluxe 4U case only slightly warm at .530 bias, mosfets measuring right at or just over 40 degrees cent. (according to my laser temp gauge).

Be checking it out in the am.

Russellc
 
#293
Playing nicely now in living room setup, silent as can be, no noise, hiss hum, nothing. Letting it break in for a while. Transformer is a 500 VA 18 + 18 Antek.
 

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#296
Bare said:
Absolutely Nothing.. I would imagine.
Remember: Komplete Newbie.. If I had the requisite knowledge, I wouldn't need to be asking 😉
So these cl60 's are the soft start?
Click to expand...


The double CL-60s off the primaries. This diagram seems to give a lot of newbies problems seeing how it is wired, for some reason. Look at some of 6L6's build threads (for power amps) and see how he rigs it up on a terminal block. Makes it very clear and straightforward.

My F-6 uses that setup as well as others and they all turn off and on with no thump. When you fire up your amp use some "test" speakers. I have a vey old pair of 6.5 inch polyprop woofers and a small set of media speakers I use for initial fireup, once I have it biased, offset zero'd, and burned in until stable. I have no need for the speaker protection, but if it makes you feel better, so be it.

Russellc
 
#297
What no review? I like your horns. The F6 is so revealing that I had to make changes in my system. Specifically changes in my crossover network and attenuation. Once I did that the sound is amazing with some of the best sound stage of any SS amp I have heard.
 
#299
wdecho said:
What no review? I like your horns. The F6 is so revealing that I had to make changes in my system. Specifically changes in my crossover network and attenuation. Once I did that the sound is amazing with some of the best sound stage of any SS amp I have heard.
Click to expand...

You know, I thought about your post when I was first listening. Upper ranges seemed a bit piercing (just a bit) so I turned down the pot to the B&C 250/QSC waveguide combo, but as a few hours went by, I was able to return it to normal setting.

I took the amp upstairs to a system with smaller 2 way speakers, and seemed fine up there as well. Amp sounds good, like all Pass amps I've built, just different. Planning on more break in today, I remember with the BA-3 it took a while, I dont know if it is break in or just adapting to it, but some time needs to pass with music I am familiar with before I feel I "know" the amplifier.

Have not hauled the amp to basement where Altec Voice of the Theatre system is.

Not much of a reviewer, but with the very short time I have spent, and this is a very preliminary statement, I think I prefer this amp over the F-5 overall, but still prefer the BA-3 over the F-6. Again, very preliminary, and my version of BA-3 is quite a bit more powerful, so this is something that may vary from system to system, and with different front ends. Both downstairs and upstairs are using BA-3 FE as pre amps, the basement Altec setup is tubes, a 60 watt DIY 6550/KT88 PP amp, and tube preamp.

When I finally went to bed last night I was liking this F-6 more and more. I stopped to power down and drill the hole that the transformer bolt uses as a mount to chassis, and holes to mount feet. Powered it back up on dining room table, let cook awhile, tweeked bias and off set.

Ready to give it another go today. I already mentioned this, but I was waiting for chassis for some time and so the boards have been assembled since I bought them a while back. As such I used the initially spec'd resistors and zeners. All I can say is that my bias and offset is rock solid. Like all my Pass projects, it is silent, no off/on thumps, no hiss hum, dead silent.

Russellc
 
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