Hello rsavas,
It is nice to see you here. Your points are valid. My only real knock on the Elektor power supply is that it does not fit in a 1U chassis. The Elektor design is robust but bog standard and not unlike the power supplies from the Elliott Sound pages as suggested previously by George Brooke. I am confident that you are right and that either of those proven designs would work.
My request was for someone to offer a creative alternative that breaks away from all of that power supply boredom! It is always good to study and learn something new. MadInventor's contribution was to that end.
Linear Technology's LT3042 can be arranged to drive a D44VH1NPN for very low noise and a high CMRR and PSRR. That would be my chosen path.
I might be mistaken, but does your board lack guard rings? I notice the components are spaced quite far.
I might be mistaken, but does your board lack guard rings? I notice the components are spaced quite far.
I just looked at the LT302 app note. Looks to be an interesting part!
Nope no guard rings. I for one have never seen guard rings used at audio frequencies.
Those Linear Tech regulators have impressive noise performance, and they were only $4 each, last I checked.
I've found that some opamp datasheets recommend guard rings, and Marantz was one off the top of my head that did exercise such trace practice. But, if your measured performance is good and stable, then no worries.
Did you happen to capture any bandwidth and curve results? I'm interested in some of the metrics and behaviors of this preamp. PS: Good job taking the initiative here.
I've found that some opamp datasheets recommend guard rings, and Marantz was one off the top of my head that did exercise such trace practice. But, if your measured performance is good and stable, then no worries.
Did you happen to capture any bandwidth and curve results? I'm interested in some of the metrics and behaviors of this preamp. PS: Good job taking the initiative here.
I have confirmed that the tone controls do in fact behave as as described in the article using a spectrum analyzer. I tried to measure noise but I quickly got frustrated as the noise performance of the circuit is too close to the noise threshold of my aging AP Portable One test set.
Jan Didden has generously made the article available online at: Linear Audio | your tech audio resource
I invite you to download it. It's a great tutorial. Doug put a lot of time and effort into writing it.
This PS was NOT designed for Carl's project, if it was, it would be quite different. It was designed for this:
I use 431 family (LMV431, LM4041, THLV431) a lot, but not to do 55 to 70 vDC. Even more resolution would be lost using a 431 (voltage divider down below 36v) when a 317/337 can literally do those voltages. Then there are different stability issues with 431. They almost give TO-92 LM317s away. The trimmer variability is a very small percentage of output, parts do age. I would design a PS for Carl's project using large front end caps, and let the regulator do a little less ripple error correcting. Would leave the output capacitance low ESR, small value < 1000uf total, including preamp capacitance. Having the case at 1.75 in. and 1A current, will cause its own issues, with power dissipation.
Mad
Hello Carl,
Have you decided on the price ?
Also if I want to build a seperate enclosure for your pre-amp tone control , any recommendation for Trafo, PS and soft-start and protect ckts?
reg
prasi
Have you decided on the price ?
Also if I want to build a seperate enclosure for your pre-amp tone control , any recommendation for Trafo, PS and soft-start and protect ckts?
reg
prasi
Hello prasi,
The details of the kit are described in the the very first post of this thread. "The cost for a 2 channel kit will be $50 plus actual cost to ship." The kit includes the hard to find parts. The balance can be purchased from Mouser Electronics. I will be providing a BOM and a reprint of the Linear Audio #5 article written by Doug Self.
There is a delay ON that avoids turn-on thumps. The project as presented is intended to fit in a 1U chassis. However if the power supply is to be internal to that chassis the box might likely have to be 2U in height.
I could be a source for a punched laser etched chassis if enough people make that request. We shall see.
Most any +/- 15v power supply that can sink 1A will work. There are several about. I have designs on hand and could provide PCBs and BOMs to anyone needing one. The trafos recommendations usually come with the selected power supply.
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MadInventor,
I am looking forward to see what you contribute.
If you make the outputs adjustable between 12 and 17 volts you will hit the sweet spot for most builders on this forum.
I am looking forward to see what you contribute.
If you make the outputs adjustable between 12 and 17 volts you will hit the sweet spot for most builders on this forum.
Carl
My redesign for your project is attached, the problem, mosfet dissipation of over 5 watts is the issue with 1U enclosure. Two options heat sink height of 1" 4.7 C/W, I would run no more than 5 watts, with 1.5" heat sink 3.7 C/W, will probably run out of clearance. The output adjustment for the attached is 14 to 16, to have a range of 12 to 17 at 1A, and stay with 1U case will require builders to choose xfmrs accordingly.
Mad
MadInventor,
I was toying with the idea of using a pair of the Amgis #L01-6354 transformers shown here at Digikey:
L01-6354 Amgis, LLC | TE2254-ND | DigiKey
With each of the transformer secondaries wired in parallel to get the needed current.
Incidentally, what part number is the Q2 device??
I was toying with the idea of using a pair of the Amgis #L01-6354 transformers shown here at Digikey:
L01-6354 Amgis, LLC | TE2254-ND | DigiKey
With each of the transformer secondaries wired in parallel to get the needed current.
Incidentally, what part number is the Q2 device??
Carl
Because Q1 has Rds of .3 ohms, you can use the 15V version of this xfmr, the regulator will work fine with only a few volts across Q1. Q2 is used for shut down +5 to gate, any NMOS will work if its Rds is low, 2N7000 is fine.
Mad
Because Q1 has Rds of .3 ohms, you can use the 15V version of this xfmr, the regulator will work fine with only a few volts across Q1. Q2 is used for shut down +5 to gate, any NMOS will work if its Rds is low, 2N7000 is fine.
Mad
Great!
Let's start a group buy list. I'll leave it up until November 1st. Expect delivery to be mid to late November
georgebrooke - 1kit
Halauhula - 1 kit
hfxrzw - 2 kits
PJN - 1 kit
kiroje - 1 kit
still4given - 1kit
GlennW - 1kit
erik777 - 1 kit
arthur - 1 kit
zrxshack - 1 kit
rock12 - 1 kit
canute - 1 kit
Somakmaitra - 1 kit
MosfetDemon - 1 kit
mik000000 - 1 kit
If you have asked to be added to the list but don't see your name be sure to let me know!
Let's start a group buy list. I'll leave it up until November 1st. Expect delivery to be mid to late November
georgebrooke - 1kit
Halauhula - 1 kit
hfxrzw - 2 kits
PJN - 1 kit
kiroje - 1 kit
still4given - 1kit
GlennW - 1kit
erik777 - 1 kit
arthur - 1 kit
zrxshack - 1 kit
rock12 - 1 kit
canute - 1 kit
Somakmaitra - 1 kit
MosfetDemon - 1 kit
mik000000 - 1 kit
If you have asked to be added to the list but don't see your name be sure to let me know!
Was the STEPS power supply bipolar?? I don't remember it to be. You will need +/-15 volts at 750mA minimum for this preamp.
I was actually thinking about using off-board Alps pots or the tone level and turn-over Frequency, and volume controls (no balance - difficult to find alps or TKD pots). Planning to try Par-Metal, but do you know of a better vendor of chassis?