And-
There is an article in an old Stereophile, February 1988, Vol 11 No.2 about a passive preamp by Ben Duncan of that time Audio Synthesis. First place I had seen that talks about the Law Faking resistors.
I might have to ask Stereoophile before I could post it. Never built it. I brought the magazine for the reviews. But it looks interesting.😎
There is an article in an old Stereophile, February 1988, Vol 11 No.2 about a passive preamp by Ben Duncan of that time Audio Synthesis. First place I had seen that talks about the Law Faking resistors.
I might have to ask Stereoophile before I could post it. Never built it. I brought the magazine for the reviews. But it looks interesting.😎
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Harry,
was this the old Audio Research preamp you held hostage for years and ffinally decided to kill in order to get rid of nasty witnesses 🙂 .... 😀
Somehow i know the knobs ....
was this the old Audio Research preamp you held hostage for years and ffinally decided to kill in order to get rid of nasty witnesses 🙂 .... 😀
Somehow i know the knobs ....
This is not mine
This passive is not mine. I appeared on another forum. The knobs
are spares from what I read. I have a canniblized C-J premiere 3 that I have used parts from. I used the knob on a passive that I built for a reveiwer for Positive Feedback and Fi magazine. I know you all think I am joking but I am sorry to say it's true.
H.H.
This passive is not mine. I appeared on another forum. The knobs
are spares from what I read. I have a canniblized C-J premiere 3 that I have used parts from. I used the knob on a passive that I built for a reveiwer for Positive Feedback and Fi magazine. I know you all think I am joking but I am sorry to say it's true.
H.H.
FBJ,
doing a passive "preamp" for balanced lines is easier than you may think.
You will need two resistors and one (log) pot for one balanced pair. You can also use a linear pot with a law faking resistor of course.
Try (not tested in this configuration) following values with a good low impedance balanced output:
+ ---1k--------------- +
in 10k pot out
- ----1k---------------- -
Klaus
doing a passive "preamp" for balanced lines is easier than you may think.
You will need two resistors and one (log) pot for one balanced pair. You can also use a linear pot with a law faking resistor of course.
Try (not tested in this configuration) following values with a good low impedance balanced output:
+ ---1k--------------- +
in 10k pot out
- ----1k---------------- -
Klaus
Thanks for the info lahk about the balanced passive preamp idea. But I haven't done much about it. I have had computer and work related problems.
Also I had been trying to post that Stereophile passive preamp schematic but when I change my drawing to JPEG or BMP files the schematic shows up either to large or to small to read. Oh well.
I did find a ALPS black beauty (100K) pot and a couple of 12.1K caddock resistors which I plan to build one of HarryHaller passive preamps designs.
Also I had been trying to post that Stereophile passive preamp schematic but when I change my drawing to JPEG or BMP files the schematic shows up either to large or to small to read. Oh well.
I did find a ALPS black beauty (100K) pot and a couple of 12.1K caddock resistors which I plan to build one of HarryHaller passive preamps designs.
Oh say, there a very good article on passive preamp design located at www.sstage.com/articles/pete02.htm
🙂
🙂
Pete Goudreau
FJB,
I worked with Pete at Alcatel! He is a mad scientist and absolutely brilliant. There is a story about his exit interveiw from another company in which he is said to have told the Human Resources guy that he was leaving the company because " This place is a cluster f*** of biblical proportions." This guy makes Jocko and me look shy. His intellect is frightening. Thanks for the link.
H.H.
FJB,
I worked with Pete at Alcatel! He is a mad scientist and absolutely brilliant. There is a story about his exit interveiw from another company in which he is said to have told the Human Resources guy that he was leaving the company because " This place is a cluster f*** of biblical proportions." This guy makes Jocko and me look shy. His intellect is frightening. Thanks for the link.
H.H.
Harry:
I remember Pete from the netnews groups in the mid to later 90s! Yesterday, I was just reading through a bunch of his older posts which I had saved from years back. I haven't seen anything from him lately though. I miss his writings 🙁
For folks starting to play around with DIY DACs, etc. , do yourself a favor: visit google and ask for Pete Goudreau on DAC mods, passive line stages, snubbers, etc.
Michael
ps - your pics are hilarious!
I remember Pete from the netnews groups in the mid to later 90s! Yesterday, I was just reading through a bunch of his older posts which I had saved from years back. I haven't seen anything from him lately though. I miss his writings 🙁
For folks starting to play around with DIY DACs, etc. , do yourself a favor: visit google and ask for Pete Goudreau on DAC mods, passive line stages, snubbers, etc.
Michael
ps - your pics are hilarious!
Biblical Proportions
More of the wisdom of Pete.
http://www.soundstage.com/articles/pete01.htm
http://www.soundstage.com/articles/pete03.htm
More of the wisdom of Pete.
http://www.soundstage.com/articles/pete01.htm
http://www.soundstage.com/articles/pete03.htm
The reason why I am asking all the annoying questions is that I built one of these preamps. I have fairly happy with it except it has some noise. There is a slight buzz through the speakers and it changes volume with rotation of the pot. I did use the audio pot vs. the regular pot. Any ideas where the noise is coming from or is this the limitation of these types of devices?
thanks in advance....
thanks in advance....
stereo pot
I wonder if I can use that volum control that lohk posted on the input or the output of my Zen preamp? 🙂
I wonder if I can use that volum control that lohk posted on the input or the output of my Zen preamp? 🙂
kimarin said:
no you cant because the Zen is not balanced. This type of attenuator relies on a balanced signal.
Ignore the lower R and ground the bottom of the pot, that'll work just fine as a shunt attenuator.
This is a picture of a Harry Haller inspired passive preamp. Simple construction, Vampire input/output connectors, DH Labs interconnect wire (with shield wire), ALPS 100K black beauty pot, and two 12.1k caddock resistors in the Law Faking design.
I connected this passive preamp in the traditional style with wires connected from input/output connectors to pot. And the sound was amazing clear with panio and vocals had a pristine characteristic. Bass was good and accurate with soundstaging and imaging presented superbly.
Well I couldn't leave well enough alone and I wanted to try something else. The picture is the way I'm listening to the preamp. The double sided PCB I got from Communcation Hud (Radio Shack) which I cut as showed (nearly cut myself many times). The shields of both wires at both ends are solder to the bottom of the board. And as for the sound, I like this way better. The preamp doesn't have that overall pristine sound anymore but a more mellow sound. All instruments are still well defined but softer. The soundstaging and imaging did not change. I encourage everyone to build a passive preamp the sound quality to price ratio is one of the best bargains in high end audio.
I connected this passive preamp in the traditional style with wires connected from input/output connectors to pot. And the sound was amazing clear with panio and vocals had a pristine characteristic. Bass was good and accurate with soundstaging and imaging presented superbly.
Well I couldn't leave well enough alone and I wanted to try something else. The picture is the way I'm listening to the preamp. The double sided PCB I got from Communcation Hud (Radio Shack) which I cut as showed (nearly cut myself many times). The shields of both wires at both ends are solder to the bottom of the board. And as for the sound, I like this way better. The preamp doesn't have that overall pristine sound anymore but a more mellow sound. All instruments are still well defined but softer. The soundstaging and imaging did not change. I encourage everyone to build a passive preamp the sound quality to price ratio is one of the best bargains in high end audio.
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