juma:
I've bought 50 pcs of J310 and I could closely matched 10 pairs. According to what I've read here before, I think I should I choose the pair with lower Id(e.g. 8.6mA) than the ones with higher Id(e.g. >10mA) in order to get lower distortion. Is that correct?
I like the J310 JFET preamp with its low 2 times gain and single rail power supply.
I've bought 50 pcs of J310 and I could closely matched 10 pairs. According to what I've read here before, I think I should I choose the pair with lower Id(e.g. 8.6mA) than the ones with higher Id(e.g. >10mA) in order to get lower distortion. Is that correct?
I like the J310 JFET preamp with its low 2 times gain and single rail power supply.
Electrolastic,
All the J310 I used (On Semiconductor, Vishay, Fairchild) had Idss about 30-40mA and that's what we aim for.
You choose Rs that will give you Id of about 10mA (usually 220R to 330R). Then we choose Rd to give us gain of 2 or 3 (680R to 1k). With PS voltage of 24V the Drain should sit at about 13-14V.
J310 is different from 2sk170 - transconductance (gm, gfs, Yfs) is somewhat lower, the -Vgs(off) is between -3V to -6V (compared to -0.3V to -0.6V for 2sk170), so you can not treat j310 as direct replacement for 2sk170. That's the reason why we use different resistors' values in similar circuit to achieve more favorable results with J310 in this line preamp.
To understand this completely, please study the datasheets of both JFETs and read carefully this article:
http://www.borbelyaudio.com/adobe/ae599bor.pdf
All the J310 I used (On Semiconductor, Vishay, Fairchild) had Idss about 30-40mA and that's what we aim for.
You choose Rs that will give you Id of about 10mA (usually 220R to 330R). Then we choose Rd to give us gain of 2 or 3 (680R to 1k). With PS voltage of 24V the Drain should sit at about 13-14V.
J310 is different from 2sk170 - transconductance (gm, gfs, Yfs) is somewhat lower, the -Vgs(off) is between -3V to -6V (compared to -0.3V to -0.6V for 2sk170), so you can not treat j310 as direct replacement for 2sk170. That's the reason why we use different resistors' values in similar circuit to achieve more favorable results with J310 in this line preamp.
To understand this completely, please study the datasheets of both JFETs and read carefully this article:
http://www.borbelyaudio.com/adobe/ae599bor.pdf
The interesting thing about Source resistance is that clearly
you can adjust the bias and gain, but what is less obvious is
that you alter the character of the sound. I have had many
examples over the years of better numbers with greater
Source resistance, but having audiophiles liking the sound
less that way.
My point: It's worth listening to these circuits as you play with
these values in addition to measuring them.
you can adjust the bias and gain, but what is less obvious is
that you alter the character of the sound. I have had many
examples over the years of better numbers with greater
Source resistance, but having audiophiles liking the sound
less that way.
My point: It's worth listening to these circuits as you play with
these values in addition to measuring them.
...
My point: It's worth listening to these circuits as you play with
these values in addition to measuring them.
That's the point of all points - listening is the ultimate purpose, measuring only leads nowhere...
The interesting thing about Source resistance is that clearly
you can adjust the bias and gain, but what is less obvious is
that you alter the character of the sound. I have had many
examples over the years of better numbers with greater
Source resistance, but having audiophiles liking the sound
less that way.
My point: It's worth listening to these circuits as you play with
these values in addition to measuring them.
Ahhh! It feels so good to know that something I learned
by myself is part of advice Papa is giving. When playing
with the Pacific phono pre circuit, the sound got worse
as the source resistance was increased. It is a delicate
balance between gain, linearity/distortion and of course,
sound.
Not really, because EQs are used in pro recording studios all the time.
I'm just saying be more specific with what you are boosting or trimming.
I think it's better not to use EQs or tone controls in hi-end at all.
If you want to roll of the highs, install a pad or variable power resistor on the high frequency horn and get a small sub.
I change out speakers all the time so I need something that works without me redoing every crossover, although that would be ideal.
Also small speakers loose bass from wrap around.
I use tone controls rather gently, if at all but a 3 to 6dB might be all thats needed.
Maybe a passive Baxandall-type can be added to the front end.
Also small speakers loose bass from wrap around.
I use tone controls rather gently, if at all but a 3 to 6dB might be all thats needed.
Maybe a passive Baxandall-type can be added to the front end.
I bet if you go to Rod Elliot's site there would be something interesting.
Expandable Graphic Equaliser
http://sound.westhost.com/project97.htm
Expandable Graphic Equaliser
http://sound.westhost.com/project97.htm
There's nothing wrong with op amps. All the music you listen to was recorded or processed at some point with op amps, including inside the instrument!
there was short period of time when I thought exactly the same ........
anyway - feel free to keep your opinion as long it suits you
there was short period of time when I thought exactly the same ........
anyway - feel free to keep your opinion as long it suits you
It's not an opinion that all the music you listen to was recorded through op amps. Even op amps used to master and "press" the CDs. That's a fact. So you are hearing the tone of op amps all the time.
Discrete is fine, but it often colors the signal. I make pro musical instruments and electronics like pickups. I use a buffer amp very similar to this JFET circuit, which is a common circuit you will find in the app notes for JFETs. JFETs have a pleasing tone. Tubes have a pleasing tone too, but neither is very accurate a lot of the time, and tubes never are.
But then accurate isn't always musical.
So my "short period of time" doing this is since about 1972. So it's not based on some fad. It's based on real world circuits.
A luthier did a double blind test to see if people could discern or preferred an op amp preamp compared to a JFET. The JFET circuit used is very similar to the JFET BOZ.
Lutherie Myth/Science: A Listening Evaluation
of Discrete vs Integrated Circuit Audio Preamplifiers in Stringed Musical Instruments
So most of the pro recording equipment uses op amps. So we want the clearest playback equipment.. to hear the tone of the op amps used in recording it.
The rest is cork sniffing.
I didn't tell that you said anything wrong or untrue , regarding myriads of opamps in signal chain , during music production ;
that issue is beaten to death , and anyone is entitled to have own opinion ;
on the other side - I can't agree with you that either tubes or jfets are music coloring devices ; good stage is good stage , whatever gain device you are using .
maybe you had misfortune to hear only mediocre jfet and tube stages .....
that page you linked to - it's just semi informative , that's why false in objectivity ; there is no any information about power supplies used in evaluation ; anyway - knowing a little about guitar circuits and technology , one can presume that batteries were used ; they're hardly any etalon PSU , at least for me .
besides that - judging any type of gain stage - used for amplifying guitar signal - can be just matter of personal preference for this or that kind of tone - same issue as preference for Trainor or Marschall or Vox or Ampeg or Orange amps ......
apples and oranges , in fact .
I'm doing these things for living little shorter (time) than you , but I'm certainly much shorter in my willingness to proclaim any expertise , as universal truth .
enjoy in your choices
that issue is beaten to death , and anyone is entitled to have own opinion ;
on the other side - I can't agree with you that either tubes or jfets are music coloring devices ; good stage is good stage , whatever gain device you are using .
maybe you had misfortune to hear only mediocre jfet and tube stages .....
that page you linked to - it's just semi informative , that's why false in objectivity ; there is no any information about power supplies used in evaluation ; anyway - knowing a little about guitar circuits and technology , one can presume that batteries were used ; they're hardly any etalon PSU , at least for me .
besides that - judging any type of gain stage - used for amplifying guitar signal - can be just matter of personal preference for this or that kind of tone - same issue as preference for Trainor or Marschall or Vox or Ampeg or Orange amps ......
apples and oranges , in fact .
I'm doing these things for living little shorter (time) than you , but I'm certainly much shorter in my willingness to proclaim any expertise , as universal truth .
enjoy in your choices
Sure it did... a 9 volt battery. These are internal preamps in the electric bass pictured. They even show the schematic from each preamp.
Also unlike some audiophile tests, this was a real double blind test. All anyone involved new was the switch on the bass said A and B.
I like tubes and I like transistors. I play through a solid state bass amp, but with a tube preamp. The tube is for coloration. It fattens up the tone.
I also have an all tube Mesa Boogie 400+ bass amp. Very hi-fi, but also very different from a solid state amp. Tube amps have output transformers, and transformers color the tone. Not a bad thing, just a fact.
But there is nothing intrinsically wrong with a high quality op amp. You can make some very low distortion circuits very easily. I think they got a bad name back in the day when people used LM741s.
I listen primarily to vinyl recordings made in the 60', 70's which used real instruments and tube or transistor equipment. The electric guitars and basses did not include built in amps either. Those recordings sound better to me that the 80's recordings which sound thinner and less natural.
My power amp is a giant op amp using discrete transistors!
However I am pleasantly surprised at how good 1 or 2 gain stages in single ended mode can make music sound more natural.
Maybe opamps gave EQ's the bad rap.
Last EQamikaze work out i did was a 3-band balanced 6dB up/down one with discrete JFET input opamps, loosely based on Cello's design and the tone control of the '83 Elektor Prelude.
I'd love to do a stretch limo version with minimum 4-layer (main) boards, preferably 8.
Just not worth a one-off, about as life sucking as constructing a Spyker in the back yard garage.
