I am wondering if someone can recommend a DIY unity gain line stage. Since I am an unbalanced person the ability to convert back and forth between balanced and unbalanced is not important.
The unity gain is important due to the 100 dB efficient speakers I use. A normal gain linestage puts the volume pots just barely cracked open. And hair trigger pot response.
I looked at the BLS, but the gain and the recommended input impedance are an issue. Several of my sources work best if they see a 100K or so load.
The buffer at the input of the Zen V4 looks like an easy solution, but would prefer using a dual rail supply. This may allow DC coupling.
Currently I have build one using a BUF634. This is sounding nice, but a discrete circuit should perform better. There are a lot of devises inside the BUF chips. This could be done much simpler.
Also a fairly low set of rails (15 - 30v) would allow use of parts on hand.
TIA,
George
The unity gain is important due to the 100 dB efficient speakers I use. A normal gain linestage puts the volume pots just barely cracked open. And hair trigger pot response.
I looked at the BLS, but the gain and the recommended input impedance are an issue. Several of my sources work best if they see a 100K or so load.
The buffer at the input of the Zen V4 looks like an easy solution, but would prefer using a dual rail supply. This may allow DC coupling.
Currently I have build one using a BUF634. This is sounding nice, but a discrete circuit should perform better. There are a lot of devises inside the BUF chips. This could be done much simpler.
Also a fairly low set of rails (15 - 30v) would allow use of parts on hand.
TIA,
George
Do you want symmetrical or single ended? bipolar, FET or Tube?
For symmetrical, take a peek at the Borbely Audio Site
And the BUF634 is really not that bad of a device. You have to be careful with rails, decoupling , etc.
Just for kicks, for my unity gain line driver needs, I've been playing around with a dual JFET source follower in front of a LM6321 buffer. Nothing fancy, but it's not bad. 😉
mlloyd1
For symmetrical, take a peek at the Borbely Audio Site
And the BUF634 is really not that bad of a device. You have to be careful with rails, decoupling , etc.
Just for kicks, for my unity gain line driver needs, I've been playing around with a dual JFET source follower in front of a LM6321 buffer. Nothing fancy, but it's not bad. 😉
mlloyd1
The LM6321 works fine by itself. If you can find one.
If not......JFETs! Bet Signoro Lloyd will sell you some of his.
Jocko
If not......JFETs! Bet Signoro Lloyd will sell you some of his.
Jocko
Oooohhh no. They're mine, all mine and you can't have them!
ah, hah, hah, hah, hah, haaaaaaah
I'd part with a buffer before I part with a FET and you can quote me on that .... 😉
D@mn- National discontinued the LM6321
What next ....
Oh well, go visit headfi . They keep up with buffers MUCH more than I do.
I've got a clock circuit to think about now (Thanks Jocko) Can't let them digital boys have all the fun ...
mlloyd1
ah, hah, hah, hah, hah, haaaaaaah
I'd part with a buffer before I part with a FET and you can quote me on that .... 😉
D@mn- National discontinued the LM6321
What next ....Oh well, go visit headfi . They keep up with buffers MUCH more than I do.
I've got a clock circuit to think about now (Thanks Jocko) Can't let them digital boys have all the fun ...
mlloyd1
Jocko Homo said:
You can easily configure BLS with gain of 1 (read the PDF for notes). Make the load whatever is required for your source.
If you use CCS on the tails the common mode rejection is high even for unbalanced input.
I know you specified balanced not necessary, but diff. pair is a common input tool.
If you use CCS on the tails the common mode rejection is high even for unbalanced input.
I know you specified balanced not necessary, but diff. pair is a common input tool.
Here ya go.
<center>
<img src="http://www.q-audio.com/images/buffer.jpg">
</center>
Just about as simple as it gets.
se
<center>
<img src="http://www.q-audio.com/images/buffer.jpg">
</center>
Just about as simple as it gets.
se
If you want to assure that it will not oscillate....
Put R2 on the other side of R1. Or add a gate damper. <100 ohms should work.
Jocko
Put R2 on the other side of R1. Or add a gate damper. <100 ohms should work.
Jocko
Re: If you want to assure that it will not oscillate....
It works fine as is. It's been out in the field for better than a dozen years and haven't had any problems with it.
se
Jocko Homo said:
It works fine as is. It's been out in the field for better than a dozen years and haven't had any problems with it.
se
Thanks!
Steve,
I will build it and compare to the BUF634 used now. It is perfect, even the rail voltage is the same. The power supply will not require a single change from the one used for the BUF's. But moving R1 should not hurt, and may help.
One question, what kind of current does this circuit draw when built as drawn up? I have the BUF634 biased to 9 ma, but they are not current limited in my simple supply.
Never used those FET's before, I will have to find a few.
George
Steve,
I will build it and compare to the BUF634 used now. It is perfect, even the rail voltage is the same. The power supply will not require a single change from the one used for the BUF's. But moving R1 should not hurt, and may help.
One question, what kind of current does this circuit draw when built as drawn up? I have the BUF634 biased to 9 ma, but they are not current limited in my simple supply.
Never used those FET's before, I will have to find a few.
George
Source for 2N5566
Maybe I should be posting this on the parts page, but looking at Digi-Key, Mouser, and Allied the 2N5566 does not look availabe. Is there a better part number to search for?
I downloaded the data sheets and I like the dual chip, one for each channel in this application.
George
Maybe I should be posting this on the parts page, but looking at Digi-Key, Mouser, and Allied the 2N5566 does not look availabe. Is there a better part number to search for?
I downloaded the data sheets and I like the dual chip, one for each channel in this application.
George
Panelhead:
http://www.diyaudio.com/forums/showthread.php?postid=155182#post155182
regards, jonathan carr
http://www.diyaudio.com/forums/showthread.php?postid=155182#post155182
regards, jonathan carr
Re: Thanks!
I drew that up for you and seeing as you said you'd prefer +/- 15 volt rails because you already had such a power supply on hand, I set the rail voltages to +/- 15 volts.
It's running about 5-10 milliamps. Depends on the FET. The 2N5566 has an I<sub>DSS</sub> that ranges from 5 to 30 milliamps, but they typically tend to run about 15-20 milliamps. You can try a lower value resistor if you like and increase the current, just make sure they don't run too hot.
See if you can get some samples from Vishay (who now own Siliconix, which are the ones we use). If not, let me know and I'll be happy to drop you a couple in the mail.
se
Panelhead said:
I drew that up for you and seeing as you said you'd prefer +/- 15 volt rails because you already had such a power supply on hand, I set the rail voltages to +/- 15 volts.
It's running about 5-10 milliamps. Depends on the FET. The 2N5566 has an I<sub>DSS</sub> that ranges from 5 to 30 milliamps, but they typically tend to run about 15-20 milliamps. You can try a lower value resistor if you like and increase the current, just make sure they don't run too hot.
See if you can get some samples from Vishay (who now own Siliconix, which are the ones we use). If not, let me know and I'll be happy to drop you a couple in the mail.
se
Re: Re: Re: Thanks!
Don't worry about it. We buy these by the thousand and shipping will be nothing more than a 37 cent stamp. If it'll make you feel any better, next time you see a "homeless" person begging for money, give 'em a little pocket change and tell 'em "This is from Steve. He says get off the crack get a damn job!" 😀
se
Panelhead said:
Don't worry about it. We buy these by the thousand and shipping will be nothing more than a 37 cent stamp. If it'll make you feel any better, next time you see a "homeless" person begging for money, give 'em a little pocket change and tell 'em "This is from Steve. He says get off the crack get a damn job!" 😀
se
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