The diyAudio Firstwatt F6

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Very nice setup flocchini.
Zman01 You could also use some nice Soviet era surplus connectors. Or current millitary, lots of different stuff on ebay.
Thanks ZM I will. I dont know a lot about the European surplus market. All the interesting outlets selling surplus stuff are gone ( as far as I know ) in Scandinavia. When I was a kid my more electronic inclined friends used to dumpsterdive at the national telecom in Iceland.
 
I have both +/-23V and +/-29V umbilical power supplies. Both are dual mono. The 23V supply is CLC while the 29V is CRC. Standard NP supplies
In attached pics the 23V is used for my SUSY F6 and M2. The 29V is for VFeT2.
M2x will be tried with both.

I think the real advantage is that you can build different amps without having to replicate power supplies.
Just my feeling.

Best

Bob

Fugly? mebe. Inordinately Complex for dubious advantage is another viewpoint.
 
ZM I was looking at your blog and in your M2 amp build with the double mono supply is the filter just a snubber C (the small blue-grey one) and CC (2x 33000uf electorlyt.) per rail and is the green resistor a bleeder resistor? Or do you have a R on the underside of the board (for CRC)?

I have now most of the parts for my M2, dont have a chassis yet and at the moment am pondering the first generation power supply for the M2. I dont want to tear down my F6. Its a great amp.

I got hold of 8x long life Kemet PEH200 (Rifa) 47000uf 63V for a low price. They are 2-3 years old but I would like to try them. I was thinking of doing similar to your M2 build i.e. 2x200 or 2x300VA toroids (almost the same price), 4 x bridges and per rail a bleeder resistor 2.2k then CRC (Cs are the 47000uf and R is either 10W 0.1R or 4x paralleled 3W .47ohm). Would that work ok. I dont have access to any simulation sw or scope. Should I bypass the Kemeths with small value polyprop. caps?
 
I have been pondering if I should build/get a passive pre (autoformer) like ZMs Iron Pumpkin in front of my F6/Altec A5 system (100+db). I tried yesterday to exchange my Aikido linestage ( ca 10-15 db gain, using 4x 6cg7 tubes) with a Slagle autoformer box ( used as my pre for many years in front of SE 300B amps).
Using a Starting Point Systems Dac 3 dac, c.a. 2v ( passive I/V), source was Tidal via Apple TV. I did not have enough gain. Phono was worse as my Boozehound phono is unbuffered ( havent built a pearl 2 yet :) ) Got some more transparent and open sound and some aggressiveness in the top, but lost bass, slam and ultimately loudness for especially some classic works ( that are rather low in Volume compared to loud close miked stuff (like Cash etc.).
The funny thing is that when I tested the F6 on my ineffective (86-87db) speakers in another room ( using a Rasberry pi, Hifiberry Dac+Pro streaming directly to the F6). I had all the slam, bass and loudness I needed.
Could this be an impedance match problem between my SPS Dac3 and F6 via Slagle atoformers, which a unity gain buffer after my Dac would fix, or am I simply in need of more gain?

My Aikido Linestage loses some transparency compared to the autoformers but sounds really nice (I use Broskie stepped attenuators as a Blue velvet pot choked the sound to a degree that made the Aikido uninvolving and boring) but I like the idea of a simple buffered autoformer.
 
Official Court Jester
Joined 2003
Paid Member
as I said numerous time - any decent passive (especially AVC) is reference to any active preamp , regarding transparency and , say, mid range purity

what passive is always lacking , except in cases of lucky impedances/cable lenghts/capacitances matching , is dynamics

so , good preamp is on par with passive regarding transparency , without losses in dynamics

easiest way to obtain this is buffering good passive ; resistive pot buffered after , inductive pot buffered in front

gain is another issue - do you need it or not

so , you know that I tried adressing all these issues with Iron :Pumpkin: ; enough written in dedicated thread , same as in Iron Pre dedicated thread

though , it's worth not forgetting that all roads lead to Rome ...... just choose good one :)
 
Yes Rome is nice ... last time I flew there. Might have to drive or walk the next time ;)
I like autoformers as well, can be challenging with revealing speakers and less perfekt source and components in the chain. Ill play around with buffers as I have a boozehound buffer somewhere ( didnt like it when I tried it some time ago after a unbuffered dac ). And see if this is mainly an impedance and not a gain issue. The reason for my pondering is of course that I have read through most of your turtle and pumpkin threads with great interest :) There is no cure for a restless mind :). Am currently trying to find a inexpensive housing for my M2, have used all the money on components, including 2x300VA trafos ;)