New Posts New Posts RSS Feed - Phono Preamp Project
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Welcome to the Graham Slee Audio Products Owners Club

 

Open to all owners plus those contemplating the purchase of a Graham Slee audio product wishing to use our loaner program: join here
Subscribe to our newsletter here (Rules on posting can be found here)


Phono Preamp Project

 Post Reply Post Reply Page  <1 34567 55>
Author
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8615
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan 2010 at 11:37pm
Originally posted by mrarroyo mrarroyo wrote:

...we are two countries separated by a common language. Evil%20Smile


Yes, this is true, and please inform president Obama that we received Winston Churchill's statue back in good condition after spending near on 60 years in the Whitehouse.... Wink

But when it comes to electronics, Silicon Valley and NASA speaks the same language, just that I try to make it more layman.

The problem with any tiny company like ours showing the world how to design, is that I have to be exact and methodical or some individuals who think they run companies to similar standards, may just be able to trip me up.

I suppose I could just say that it sounds out-of-this-world or mind-blowingly-good, which incidentally it does, but I'd be stealing everybody else's line...Hug
Not simple enough for Google-Bot to understand...
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8615
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 2010 at 2:08am
So far so good...



The left hand screen is the design copied into the windows software because I cannot get a hardware compatible MS DOS 5 printer these days. Even with the disadvantage of having to do transfers on floppy disc, the "machine-code" version of this software is mega-fast compared.

Time for checking, final tweaking, then generating the gerber and drill files before emailing to the PCB manufacturer for some prototype PCBs.
Not simple enough for Google-Bot to understand...
Back to Top
discrete badger View Drop Down
Senior Member
Senior Member
Avatar

Joined: 14 Jul 2009
Status: Offline
Points: 319
Post Options Post Options   Thanks (0) Thanks(0)   Quote discrete badger Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 2010 at 7:21am
Graham, when drawing out the board like that, how much are you thinking about the sound quality effects of your decisions versus the more obvious task of getting everything to just fit onto the board and be connected in the right way?
Back to Top
leo View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 13 Jan 2008
Location: uk
Status: Offline
Points: 53
Post Options Post Options   Thanks (0) Thanks(0)   Quote leo Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan 2010 at 5:00pm
looking great,  its giving me itchy fingersEmbarrassed     would love a go at this, may even  knock it up on vero (if Graham don't mind)  until  the kit is released,  better have a trip to Craplins to see what bits they don't haveLOL

Its nice to see a diy phono stage, don't seem to be many of these about, anybody else having a bash?


Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8615
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan 2010 at 6:09am
Originally posted by leo leo wrote:

looking great,  its giving me itchy fingersEmbarrassed     would love a go at this, may even  knock it up on vero (if Graham don't mind)  until  the kit is released,  better have a trip to Craplins to see what bits they don't haveLOL

Its nice to see a diy phono stage, don't seem to be many of these about, anybody else having a bash?




Like the Avatar! Wink

"Twas twillig and the slithy tove..."

Graham don't mind!

Looking forward to your findings - hope craplins has some veroboard - wish I had some left too!
Not simple enough for Google-Bot to understand...
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8615
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan 2010 at 6:56am
Originally posted by discrete badger discrete badger wrote:

Graham, when drawing out the board like that, how much are you thinking about the sound quality effects of your decisions versus the more obvious task of getting everything to just fit onto the board and be connected in the right way?


Good question!

Did you know that when you are listening to music you are actually listening to the power supply? Shocked

Here is how... (Transistor Man picture from "Art of...": points B and E is the input signal and points C and E are in-effect the amp controlling the power into the speakers, headphones, a preamp driving a power amp etc)



We will assume the power supply is nice and quiet with enough current to prevent it "wobbling" in sympathy with the music.

What else could go wrong?

Even with short and reasonably thick PCB traces, a "dot to dot" will have sufficient impedance for one thing drawing power to affect another thing drawing power (like the headlights dimming when you switch on the rear window demister, or that recurrent "MOT-pass because they don't test them together" Ford earth fault which turns the rear indicators off when the brake lights come on).

And the thing many designers forget: currents flowing into and out of the same point at the same time - it can't be done - that point cancels out completely when the currents are the same and in direct opposition - a case of a piece of wire that is solid, it is there, you can see it, you can even "bleep it out", but it's not connected!

Therefore, you may be able to make out a number of tracks all going to the same place by different traces? That place is the lowest impedance point of whatever current we are wanting to connect to. Often the star earth is the only thing considered, and often the star earth is just a "pretty flower picture" with a silly thin track then leading back to the common "ground" connection - so all those currents still modulate one another (search the internet if you want a good laugh). In our case the PCB is routed to avoid one thing modulating another. We may only be talking about pico-amp differences, but those are sufficient to confuse the picture as the all-important "clues" are contained in the micro-information.

Some designers adopt the ground-plane approach, but the current still takes its own path as if the rest of the ground plane didn't exist.

So yes, I'm thinking most of the time about sound quality effects of my decisions, and often miss a connection because of it Cry. So right now I'm correcting things like that, doing print-outs, checking again etc.

Not simple enough for Google-Bot to understand...
Back to Top
RobW View Drop Down
New Member
New Member
Avatar

Joined: 10 Jan 2010
Location: Canada
Status: Offline
Points: 24
Post Options Post Options   Thanks (0) Thanks(0)   Quote RobW Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan 2010 at 8:07am
Hey - I was just reading about "Transistor Man" on the weekend. Thanks for the tie in.

I very much like the thought-shift provoked by the idea that listening to music is basically listening to the
power supply. So is the source signal then just the mechanism that controls a "rheostat" between the power supply and the transducer? And all the other bits and pieces in the signal path are just about ... what ... balancing, filtering, controlling ... ?
I need to look over your schematic closely to see if I can see what you're talking about re PCB routing to avoid modulation.
So many questions.
Back to Top
 Post Reply Post Reply Page  <1 34567 55>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.109 seconds.