Warming up first channel, Variac at 120V, 2.3 millivolts offset, .447 V......slightly warm sinks.
Old original F5 was set around .62V, Nelson's article says this one from .52 to.80 V, so now up to .65, V, offset 4.8.....sinks noticably warmer, but not much.
After few minutes, up to.78V, offset -2.6 mV,
Still just warm. This is a 3U 400mm chassis.
I really expected more heat?
Seems stable at 3.4 mV offset and .78V bias. Power down and do other channel.
Russellc
After few minutes, up to.78V, offset -2.6 mV,
Still just warm. This is a 3U 400mm chassis.
I really expected more heat?
Seems stable at 3.4 mV offset and .78V bias. Power down and do other channel.
Russellc
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Second channel warming, 120V on variac, 5.8 mV offset .67V bias. Top on, cooking for a bit. Bias drifting ever so slightly up to .71, offset down to .8 mV, looking good so far!
Little more cooking, re set, power up both channels together, little more cooking, final touch up and music time!
If my original F5 was at .80 mV it would be hotter than a two dollar pistol. This F5m is nice and warm, but far from "crikey" hot ..
Russellc
Little more cooking, re set, power up both channels together, little more cooking, final touch up and music time!
If my original F5 was at .80 mV it would be hotter than a two dollar pistol. This F5m is nice and warm, but far from "crikey" hot ..
Russellc
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🤭 whoops, well at these temps I'm not to worried, can turn down a bit. I really worried if these 3U heatsinks would be sufficient, so I got the extra deep 400 mm version, probably not necessary, especially at a lower bias
There, .67V and 3.2 mV offsett
There, .67V and 3.2 mV offsett
Well, that explains it! Still not sure the 400 mm deep is necessary, but it gives a nice long low profile look!
On final cook, touch-up, fasten top on and hook it up to some speakers
Russellc
On final cook, touch-up, fasten top on and hook it up to some speakers
Russellc
Re warmed up sans variac, readjusted warming in system. Speakers hooked up, either it doesn't work or is DEAD silent!
Streamer on, music!
Russellc
Streamer on, music!
Russellc
Whoa....forgot to reverse speaker hook ups, image jumped forward 5ft! Seems this one, like Aleph J, is particularly subject to this effect.
Russellc
Russellc
I don't recall my original 5 being this open, maybe it is the additional 2nd harmonic over that version. Very sweet sounding.
Great project, super simple, inexpensive, chassis not as expensive either. First listening is this beats original, for my tastes.
Original is upstairs, need to haul this up there for comparison.
Right now nice Iron pre upstairs, so older beta build Iron Pre and Tekton speakers sound flat amazing. Time to sit back a minute.
Great project, super simple, inexpensive, chassis not as expensive either. First listening is this beats original, for my tastes.
Original is upstairs, need to haul this up there for comparison.
Right now nice Iron pre upstairs, so older beta build Iron Pre and Tekton speakers sound flat amazing. Time to sit back a minute.
Been playing hard all this time, tektons rattling things. Now to pause remeasure, touch up, screw on top and another one done.
No rest for wicked, plethora of pinjatta package just came in mail.....
Russellc
No rest for wicked, plethora of pinjatta package just came in mail.....
Russellc
Now hooked up to X's XSD speakers. Doing TV duty for a minute then switch to music.
These are 4 ohm speakers and like lots power, although fairly efficient, around 92 dB. What they really need is dampening factor.
We will see how music does. Aleph J faced a similar problem, sounds ok, but can be better. My other speakers play fine with Aleph J. Just playing around with new toy. Really liking this long and low look of the 3U chassis.
These are 4 ohm speakers and like lots power, although fairly efficient, around 92 dB. What they really need is dampening factor.
We will see how music does. Aleph J faced a similar problem, sounds ok, but can be better. My other speakers play fine with Aleph J. Just playing around with new toy. Really liking this long and low look of the 3U chassis.
Gotta say, as nice as blingy builds are, the best thing on this forum is when someone builds a thing and is genuinely stoked with the result. 🎉
Just curious. Many years ago my "first " First Watt clone was the F5, original version, still servicing bedroom system. When the new one came out,
just had to do it.
Not sure what words to describe, original was good enough I realized tubes were a type of sickness, and if I could get this sound from jfet/mosfet,
the sand die was cast. After many builds here However, a certain "thin" or "dry" not meant in a bad way, I just dont know how to describe it. F6 seemed to also share this trait. I kept F5, but converted F6 to AlephJ. Now things are cooking! M2, BA3 also closer to the mark I sought. XA 252 nailed it!
Then new F5m. As described, a touch more 2nd order harmonic spectra....after a very sucessful session with Tektons I hauled it upstairs to bedroom system where original F5 plays TV, M2 handles Streamer and turntable. Speaker are small stand mounted 7.5 inch 2 way that suck a lot of power and are only 85 dBish.....but these amps are plenty for room....I did notice that F5m under this speaker was a bit to the thin side, really not the best load,so I think it will end up driving the tektons with which they rock perfectly.
Speaking of not the best load, I hooked it up to the main living room to X's XDS dipole speakers. First listen was Anjali, which is a fine recording, almost entirely strings, hardly "bombastic" very calm. Lots of string tones, plucking and so forth. Image slightly shrunk down, not bad, tonally beautiful which was surprising. As I found more demanding music it also surprised, image shrunk a bit, mostly sins of omission rather than commission. Faired better than Aleph J here.
Like original F5, simple build, great result for the effort. Not bowling over the other First watt clones, not beating (in my opinion) BA3, and simply not in power catagory of XA 252, which beats everything! (in my opinion).
In short, a great update to original F5. Not everyman's amp, but for those with proper speaker efficiency and ancillaries, can sound very, very nice for money and effort expended.
just had to do it.
Not sure what words to describe, original was good enough I realized tubes were a type of sickness, and if I could get this sound from jfet/mosfet,
the sand die was cast. After many builds here However, a certain "thin" or "dry" not meant in a bad way, I just dont know how to describe it. F6 seemed to also share this trait. I kept F5, but converted F6 to AlephJ. Now things are cooking! M2, BA3 also closer to the mark I sought. XA 252 nailed it!
Then new F5m. As described, a touch more 2nd order harmonic spectra....after a very sucessful session with Tektons I hauled it upstairs to bedroom system where original F5 plays TV, M2 handles Streamer and turntable. Speaker are small stand mounted 7.5 inch 2 way that suck a lot of power and are only 85 dBish.....but these amps are plenty for room....I did notice that F5m under this speaker was a bit to the thin side, really not the best load,so I think it will end up driving the tektons with which they rock perfectly.
Speaking of not the best load, I hooked it up to the main living room to X's XDS dipole speakers. First listen was Anjali, which is a fine recording, almost entirely strings, hardly "bombastic" very calm. Lots of string tones, plucking and so forth. Image slightly shrunk down, not bad, tonally beautiful which was surprising. As I found more demanding music it also surprised, image shrunk a bit, mostly sins of omission rather than commission. Faired better than Aleph J here.
Like original F5, simple build, great result for the effort. Not bowling over the other First watt clones, not beating (in my opinion) BA3, and simply not in power catagory of XA 252, which beats everything! (in my opinion).
In short, a great update to original F5. Not everyman's amp, but for those with proper speaker efficiency and ancillaries, can sound very, very nice for money and effort expended.
Well, except by total boneheaedness, I carelessly sent a giant transient through it and it is in the amp hospital!