A Few Finished Projects--Pics!

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Samuel Groner

Well-known member
Joined
Aug 19, 2004
Messages
2,940
Location
Zürich, Switzerland
Hi

Thought I'd post a few pics of recent projects--here we go:

No intention to bore, but first another GreenPre: green_pre.html
This are the boards I won on the "Thanksgiving donation" 2005--took a year to finish... I did apply some slight changes to the standard circuit. Works very well, a bit much hum though, will need to have another look at this. If I just wouldn't have messed up the level meter labeling. :evil:

Now an opamp test jig: opamp_test_jig.html
Allows me to quickly test opamps (discrete or IC) for various parameters (noise, stability, slew-rate, offset etc.). Very helpful for daily life!

Third a little headphone amplifier with a simple built-in mixer: headphone_amplifier.html
Perfect for basic personal monitoring. Cool in the lab for testing new gear too. No inside pics because it is a pain to open and close this beast.

Last but not least a 8 channel mic preamp with built-in (and bought in) AD: monte_zucchero.html
I designed this for a lab project at university, and my four student colleagues each built a unit. Big and heavy. But that's how we like it!

Samuel
 
:shock:

!!!!!glung!!!!!!

OUT-FRIGGIN-STANDING!

Really.

Excellent work.

please tell me about the 8-ch A/D buy-in thingie. Is it ADAT or TDIF? (I see optical and D-sub-25 connections and I don't recognise the board)

I do love the front panel on the first unit also (dual green pre) -Is it a Scheaffer?

Keith
 
Works very well, a bit much hum though, will need to have another look at this.

I see that you have the input connector grounds running to the chassis.

The best grounding scheme I have found is to connect all the XLR pin 1's together with a piece of wire (I used a piece of tinned wire) & run this to the star ground.

http://1176neve.tripod.com/id28.html

I had to replace the mains trafo in these pics with a toroid owing to hum problems, but once this was done, it became dead quiet.

Peter
 
[quote author="peterc"]The best grounding scheme I have found is to connect all the XLR pin 1's together with a piece of wire (I used a piece of tinned wire) & run this to the star ground.[/quote]

+1.

I just opened a couple of the Summit EQ-200's and I have to say I was delighted to see that they'd done that too. Nice and accessible, out there in the open as soon as you pull the lid off.

Makes hum-chasing a VERY simple matter.

In fact, better yet is to go through a SPDT with center-off, located on teh back panel. That way you can switch between ground link ground lift (center) and capacitive ground, as options.

Keith
 
Looks really, really good! I espacially like how your "mittelbronze" frontpanel has turned out. My next project will have a "mittelbronze" panel for shure.....


:thumb:

@SSLtech: yep, that's Schaeffer alright.....
 
Come on Samuel, it's a bit scruffy. :razz:

Excellent looking work - very neat, and nice design.
 
Hey, thats professional work :shock: :shock: .
Everything is so neat and proper. I wish my cases would like yours. Instead they look like a bazar :roll: . This AD Converter is very interesting. Can you give us any details? @ Peter: I'll try your grounding scheme, some of my DIY gear has hum problems, too.
Regards
Bernd
 
Samuel, that´s a great show. I´m really impressed.
With your OpAmp test jig I guess we can expect a lot of OpAmp analyzing in the future :grin:
congrats
:thumb:
 
Nothing boring about that green preamp! Very impressive build.

This is the 2nd time I've seen a green built with 0ohm resistors instead of straight wire jumpers. Can anyone explain the value of doing this? I'm really curious; I know there must be some reason.

Thanks, Kato

zero ohm vishay metal film resistors at mouser - it's weird that they're listed at 5% tolerance (of 0Ω)
 
[quote author="peter purpose"]schön Schweitzer technik.... :thumb: :thumb: :thumb:[/quote]
So ist Richts!

-Speaking of beautiful...
sophia.jpg


:shock:

Ah.... Next you'll be posting one of Ms. Lolobrigida... :sigh:

:green:

Keef
 
This is the 2nd time I've seen a green built with 0ohm resistors instead of straight wire jumpers.

Automatic parts placement machines cant deal with bits of wire, they need something recognisable like a resistor to pick up. Hence the familiar shape but with a piece of wire inside & not a resistor.

Sometimes they actually have fuses inside as well.

Peter
 
Thanks for your interest!

Please tell me about the 8-ch A/D buy-in thingie. Is it ADAT or TDIF? (I see optical and D-sub-25 connections and I don't recognise the board).
ADAT (up to 96 kHz) and AES/EBU (up to 192 kHz).

Is that an RME AD converter from the Octapre?
It is.

The best grounding scheme I have found is to connect all the XLR pin 1's together with a piece of wire (I used a piece of tinned wire) & run this to the star ground.
Thanks for the hint. However, I think that it is not a grounding problem related to pin 1 connection but rather simple magnetic interference, because the hum is much more present in channel one (being closer to the PSU), mostly even order and does not dissapear if nothing is connected to input and output (with input temporarily shorted right at the input connector and hum traced on 'scope). But I'll need to do more testing to be sure.

With your opamp test jig I guess we can expect a lot of opamp analyzing in the future?
There's a whole drawer full of IC samples waiting for merciless THD+N measurements. Might take several month though until that's done...

Could you give some details of your opamp test jig? What you built in and why.
www.groupdiy.com/index.php?topic=12509

Samuel
 
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