DIYHiFi.org

The several hundred microvolts of noise might be masking it. Are these a new design from Per-Anders? I like via studded ground plane but most PCB houses charge by the hole.

What about the regulator design discussed in these pages:
http://www.tnt-audio.com/clinica/regula ... ce4_e.html
http://www.tnt-audio.com/clinica/regula ... ple_e.html
?

You are walking a slippery slope. You are using this forum thread to promote a comercial product (a kit) from a company which is linked to your comercial website! It could very easily considered a conflict of of interest and a abuse of the forum. How do we know you don't have financial ties to the product? this may not be your intention but why give even the slightest appearence of abuse.

I would have the manufacturer put the product in the Sponsered threads section and stop trying tip toe around the rules for comercial products. I leave this to the moderators to straighten out but it seems worth nipping in the bud before it becomes a real issue of abuse.

I am going to temporarily lock this thread until "we" (ok, "I") have time to look into the matter that Phred raises.

Won't be until tonight, so everyone stay calm.

Jocko

OK......I've "talked" to Greg and Mike, so I am opening this back up. if anyone really needs to know what went on, you can ask me. If not, let's drop it and move one.

Jocko

Oh no... not Mike...
Is it really necessary for you guys to start a business with such more or less trvial things...? I thought this isn't "Wall Mart" here...

Moving on....

Returning to purely technical considerations concerning the shunt regulator shown, the large amount of noise measured by Greg is way above the levels expected for a "low noise" regulator. The voltage reference used in the regulator is the LM 285-2.5 which has a typical noise of 120 uV over the range of 10 Hz to 10 KHz. This compares with about 7 uV for an LM329 over the same frequency span. The output impedance of this reference is inductive over this span an a 0.1 uF cap is put across this reference for noise filtering but will probably only increase the noise of the reference around 6 KHz. Most other low noise regulators use an RC filter with a subsonic corner frequency between the low noise reference and the op amp noninverting input. The voltage reference voltage is out side the common mode input range for the LT1115 which should be 5 volts above the negative supply rail. Running outside of the common mode range can cause an op amp to drop out its feedback loop or even be damaged. If this happens you could wind up putting excess voltage on the circuit under regulation damaging it as well. that is the real reason I am making such an issue out of common mode limits. Don't find out the hard way, read and understand your data sheets!

There are several other very questionable design practices such as the lack of high frequency supply decoupling for op amp supply pins. Walt Jung got bit by this big time with the AD797 op amp in a boot strapped supply voltage regulator scheme like this.

If I were the designer, I would go back and throughly read the Voltage Regulator articles on Mr. Jung's websight. Both regulator polarities could probably use the same board with strapping options as to how the current source is connected... same parts even and better performance most likely. This would allow the use of existing center tapped full wave raw supplies.

I honestly don't feel this design is close to optimized for the parts and topology used and is definitely not ready to unleash on someone that could cook his preamp circuit with a potentential unstable regulator circuit. Buid a conservative and well tested design or sure as hell someone out there will have problems that you may not know how to fix over the phone. I know I have not been very gentle but much nicer than the first customer with a problem that will encounter unless you really understand and test your design thoroughly.

Fred

Hi Fred,

Noting your concerns - Mike's PS that landed in my lap just as I was wanting to do some chip tests was timely. Being a shunt reg - not commonly available off the shelf I posted to the forum an innocent contribution. I had no real intention of investigating the design intensely more than to see if it would suffice for the testing regimen I proposed (IC PSRR) where I need to modulate the supply.

Your post made me look more closely at the design and I can only agree that it would be possible to improve it. Side issue. Will it do my test function - possibly. Great if it will.

Phew. Sorry for posting.

Cheers,
Greg

Well, we can keep shooting holes in designs done by others or argue about PSRR and noise figures and how they differ with each circuit. How about we put the DIY back into DIYhifi.org and whip something up that pleases everyone?

Best regards,

Sander Sassen

Guys,

This is getting stupid.........is Fred now a moderator or the self proclaimed policeman of this forum. His sole purpose seems to be to attack anyone he fancies will little contribution on his part...............this is getting really annoying. Some moderators seem to have this attitude as well.

This forum is to promote the hobby, and if critisism is warranted let it be constructive and new members should be encouraged and shown errors they have made in a polite way.............a recent comment "get a new hobby' by one of the moderators was uncalled for.

Greg who is willing to contribute something of substance gets attacked for no reason, I have been attacked................funny thing the attackers have not contributed anything of substance but take pleasure at snipeing at anyone that does. Maybe they should get real jobs and stop using this forum to vent their frustrations or better still contribute something useful.

Regards,

Jam

As I mentioned, in my last post, how about we put the DIY back into DIYhifi.org and whip something up that pleases everyone?

Best regards,

Sander Sassen

Sander, well put.

Regards,

Jam

Now Jam... it seems like you don't know Phred...???!
Sometimes we have to get a slap on our face to see what's in front of us.
Fred's approach is to make you use your head, and don't give the soup to your mouth.
I like thinking. I like challenges. I like that.

Please don't take him wrong, nobody's attacking anyone.

His footer says it all:

"Remember, I'm pulling for you. We're all in this together."

Get it?
Now go back and put some water on the sponge, the soldering iron is waiting.

PS: there's always something between the lines, even if you are being spanked.

Carlos,

Please get real..............there are proper ways to conduct yourself in the forum and Fred has pushed past the limits. I do not doubt his knowledge or technical ability but he has to change his attitude.

We are trying to encourage new members and promote the exchange of ideas not scare people away.

Regards,

Jam

I am subject to moderetion like anyone else. It seems an unauthorized moderater is now trying to moderate me. If shooting holes is giving someone resources to fix obvious design flaws, I best buy more ammo. I have told Mike eq how to fix his regulator with some very simple changes and given him the link find out why to make make these changes. This is ground well covered by Walt Jung, Jan Didden, and Andy Weeks. I wish I had someone to shoot holes in my designs so I could make them better.
My big crime is pointing out that not everyone who can draw a schematic
is an audio designer and that topology alone does not make a good design. It seems ironic that I get the most flak from someone who's designs I had the littlest to say about.



Greg does not sound mortally wounded here and gets exactly the intent of my post about improving the design. I would like to know who the official guy to suggest specific improvents is, so I can Email him with any observations so he can filter it down to be acceptable to everyone. This starting to sound exactly like the whining at the old forum. The one that threw several of us off. Do I have to go start my own forum now for the same reasons we left the other one.