Steve Eddy said:
Thanks Steve, I was on a panel with him, but he had a kidney stone and had to leave. I like this quote...
>The 2N4401 and 2N4403 transistors are specified to be general purpose switching and small signal amplifier transistors. Although they are not specified for low noise applications, they have a low base spreading resistance which makes the suitable for low noise amplifiers. An engineer once told me that some audio designers consider the noise performance of the 2N4401/2N4403 pair to be a design secret. Hence they sometimes remove the numbers to keep others from knowing what transistors they use. The original transistors which I developed the circuit with were the 2N5210 and 2N5087. The Motorola data book specifies these as low noise transistors. When I replaced them with the 2N4401 and 2N4403 transistors, the signal to noise ratio was improved by about 4 dB.<
They WERE a design secret when I discovered them in 1968. Please note date. That was 40 years ago. What were you doing 40 years ago, Scott? I mentioned the 2n4401-4403 pair as low noise devices in a LTE to 'Wireless World' in 1971. It was not published, but referred to the author of the low noise article I was addressing, and my contribution was footnoted by this author in 'WW' in 1972, fully 4 years after I made this discovery when I worked in the Ampex audio department.
This is the parts pair that we used in the Mark Levinson JC-1 pre-preamp first introduced in 1973. It is also the recommended part pair in my patent of the same circuit.
This is the parts pair that we used in the Mark Levinson JC-1 pre-preamp first introduced in 1973. It is also the recommended part pair in my patent of the same circuit.
john curl said:
And best to use whatever gives one the greatest satisfaction at the end of the day.
se
john curl said:
I might have been riding the back of one of those big white Leach garbage trucks. Lots of fresh air.
For everyone, this is a good example of: It doesn't exist; it exists, but it is not important; and we invented it. It was new and fresh in 1968. It was not believed in 1973 when we introduced the JC-1 pre-preamp, and by the late 70's, it was considered obvious. Happens all the time.
john curl said:
Pardon my absolute ignorance of these matters, but it looks like to me as if the BJT power supply transient response ends up dominating the fet's response.
That would mean the 100uf 16V electrolytic becomes critical as well.
Ah, it's all critical in the end, like missing 10 feet in the middle of a rope bridge. Not gonna work very well.
Ah, it's all critical in the end, like missing 10 feet in the middle of a rope bridge. Not gonna work very well.
Mr Curl
What do you think of Sanyo Jfets?? Looking at datasheets seems to me 2sk222 can match the 2sk170 in noise and some parameters are better. 2Sk223 is a 80 volt version. The datasheets secify noise spec.
I am thinking of using these in a frontend of a amp and i like using sanyo as their range of bjts are excellent.
Alex
What do you think of Sanyo Jfets?? Looking at datasheets seems to me 2sk222 can match the 2sk170 in noise and some parameters are better. 2Sk223 is a 80 volt version. The datasheets secify noise spec.
I am thinking of using these in a frontend of a amp and i like using sanyo as their range of bjts are excellent.
Alex
That looks worth a try, it can't hurt to try. The 2nV with Rg of 1k would require a rather cold temperature.
Scott, I wonder if we could get you to ease up on the use of the quote button. It clutters up the thread and IMHO there's simply no need to quote if you are the next post in line unless you are selecting only a portion of the post to respond to.
Thank you
Thank you
scott wurcer said:
😀 . -200 degrees Celsius would easily make it. Or, VERY experienced designer! 😉
dimitri,
You mean the front end of Mr.Curl's Vendetta phono amplifier? 😉
Interesting choice...........a study in low noise design.
Jam
You mean the front end of Mr.Curl's Vendetta phono amplifier? 😉
Interesting choice...........a study in low noise design.
Jam
- Status
- Not open for further replies.