I received some big power resistors yesterday. I'll test them out for my friends in incandescently 
challenged parts of the world and report back after the weekend.
challenged parts of the world and report back after the weekend.
yes Olaf, you are right......
I just tried them with 54V and and the end of the line I had at the drain 0,8V
UUUPs! I did it not do it again with the second bulb parallel.....
seems I was too fascinated, lurking in my basement for a fitting bulb, saw the red one, measured 23 Ohm cold resistance and Ohms Law didn't exist any more in my brain.....
so we enjoy two infrared bulbs in our home and we can cure two persons at one time.....😀
My good friend Tony Wong's SIT amplifer almost complete .. Here's some pics of the amp..
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I am just hearing since two hours the SIT Amp .......
PSU is at the moment the normal FW version, bias at the moment a nine volt block with a 5 k pot. (Former solution was a 2 Ohm resistor, giving 5V, but I had a PSU with 28V in this case)
I use just now the normal PSU so I can switch between my different clones, at the moment a crippled F4 with an xformer M2like.....
With this solution I cannot touch exactly the sweet points Mike mentioned, but I get 2,4A and about 10V at the output node over the SIT and the CCS.
First hearing with the SIT last days seemed to me a bit disappointing, quite normal sound I thought.....
My F4 and Xformers sounds better.... So I build one channel F4 and one channel SIT in the same case.
And ..... F4 and xformer did not sound better was the first experience.....
The somewhat dull experience with the SIT was more due to the pre I use at the moment.
So I could look new at the real differences....
SIT: very relaxed, never harsh (triode effect?), more fine details, more room around
modified F4: more attack, the medium area shows a bit more presence, closer to the box, bit less details.
At the moment I prefer the SIT.....🙂
So I am encouraged to build the second channel. Must I look for two different bias circuits for each channel? I suppose so....... Otherwise sound could be mono.
In Aleph P first version Nelson used for biasing the IRFs only one biasing point from the Zener string but put 100k in the two cables going to the gates.
Any hint?
PSU is at the moment the normal FW version, bias at the moment a nine volt block with a 5 k pot. (Former solution was a 2 Ohm resistor, giving 5V, but I had a PSU with 28V in this case)
I use just now the normal PSU so I can switch between my different clones, at the moment a crippled F4 with an xformer M2like.....
With this solution I cannot touch exactly the sweet points Mike mentioned, but I get 2,4A and about 10V at the output node over the SIT and the CCS.
First hearing with the SIT last days seemed to me a bit disappointing, quite normal sound I thought.....
My F4 and Xformers sounds better.... So I build one channel F4 and one channel SIT in the same case.
And ..... F4 and xformer did not sound better was the first experience.....
The somewhat dull experience with the SIT was more due to the pre I use at the moment.
So I could look new at the real differences....
SIT: very relaxed, never harsh (triode effect?), more fine details, more room around
modified F4: more attack, the medium area shows a bit more presence, closer to the box, bit less details.
At the moment I prefer the SIT.....🙂
So I am encouraged to build the second channel. Must I look for two different bias circuits for each channel? I suppose so....... Otherwise sound could be mono.
In Aleph P first version Nelson used for biasing the IRFs only one biasing point from the Zener string but put 100k in the two cables going to the gates.
Any hint?
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not necessarily ....... bias supply is virtual gnd for gates , so you'll not have mono
you can use one supply , but separate bias nets for each channel
THX Zen Mod!
Hi tea-bag, happy to see buildings like mine.......How do you like the sound? 😀
440uF at the output?😱 then you hear only half the orchestra!😀
Hi tea-bag, happy to see buildings like mine.......How do you like the sound? 😀
440uF at the output?😱 then you hear only half the orchestra!😀
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I dont have a decent test speaker yet to say, and I am only mono.
I have some M-Lytics I will put on at some point. Source is currently an Ipod.
Still if I had to make a quick guess, soft. Likely not enough gain to drive it.
Only mono....?
Sometimes I think I do not like stereo, I like more one channel this amp and other channel different amp......seems to be more fun for me.🙂
Sometimes I think I do not like stereo, I like more one channel this amp and other channel different amp......seems to be more fun for me.🙂
It was only a joke...
You use the bulbs....... I see the light in the pictures. I would try them too immediately but you know we have no 100W and no more 60 Watt, we have to use energy saving bulbs.
Not to speak of 300 W.....
I am really interested to hear your opinion about the sound..... Soft is for sure correct, I could hear the harshest CDs still a pleasure.......
You use the bulbs....... I see the light in the pictures. I would try them too immediately but you know we have no 100W and no more 60 Watt, we have to use energy saving bulbs.
Not to speak of 300 W.....
I am really interested to hear your opinion about the sound..... Soft is for sure correct, I could hear the harshest CDs still a pleasure.......
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they already told ya - use halogen sticks
they're funnier , too 😉
you can even use heater elements of so called "quartz" furnace ( called as that because glass used as envelope for heating wire is sort of special )
they're funnier , too 😉
you can even use heater elements of so called "quartz" furnace ( called as that because glass used as envelope for heating wire is sort of special )
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I had a chance to try some power resistors today for those of you in incandescently challenged parts of the world. They are 120W. They have a green coating on the element, and ceramic or porcelain insulators on the steel mounting brackets. You can see they are quite large.
I wired five 4 Ohm resistors in series, so I could try tapping off different load values. You don't have to do that unless you want to; just use three in series for 12 Ohms.
They get hot. They cook along at 100C, like a light bulb. The mounting brackets never got hot, apparently due to the insulation. They work just fine, and work without a heatsink. They also have a nice retro Forbidden Planet sort of look.
If you're concerned about accidentally touching them you can always cover them with a tube cage.
I wired five 4 Ohm resistors in series, so I could try tapping off different load values. You don't have to do that unless you want to; just use three in series for 12 Ohms.
They get hot. They cook along at 100C, like a light bulb. The mounting brackets never got hot, apparently due to the insulation. They work just fine, and work without a heatsink. They also have a nice retro Forbidden Planet sort of look.
If you're concerned about accidentally touching them you can always cover them with a tube cage.
