ATEST

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Andrew
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#1 ATEST

Post by Andrew »

I got sick of being out bid on e-pay for a decent spectrum analyser and after playing with the Audio Precision at work (can't afford one of them either) I realised how useful a decent measurement system would be!

I decided the most cost effective route would be based upon a sound card. That way you get into the commodity pricing as you're amortizing the cost of the card across all those hundreds of other folks/musicians etc who buy them. Moreover, if the system is driven by a PC, its a great way to share information etc without having to take photos of scope screens. And, as I already have a PC and most modern instruments I have been close to are just a PC plus a data acquisition system, I thought why not, the sound card and PC can become my acquisition system and linked signal generator etc.

The problem with sound cards is that they are designed for fixed line-level inputs and outputs. Depending on the card this may be between 1V and 5V RMS maximum. They are also not tolerant of overloads - accidentally deliver 20V or 200v into your sound card input and you will most likely be looking for a new sound card. Also the input needs to float, you don't want to be sharing the sound card's ground.

So I decided to take a look around and leap into the sound card world. In the end, I jumped for this to provide the front end, seemed simpler than doing it myself completely from scratch.

http://www.pmillett.com/ATEST.htm

I have a decent RMS meter so I was just going to build the front end but if you buy the parts from Mouser and/or Digikey the whole free shipping thing kicks in and changes the economics. So, I thought I'd go the whole hog and build both sections.

Board arrived today, its a nice job.

Just started work on it. I won't post pics since it looks just like the one in the link.

Andrew
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Andrew
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#2

Post by Andrew »

It lives, now for the sound card bit...
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Toppsy
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#3

Post by Toppsy »

So that's what you've been doing whilst being snow bound in the wilds of Scotland. :wink:

Nice one. So does it do what it says on the label :?:
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Andrew
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#4

Post by Andrew »

Ah, I need a decent sound card for that, just need to clear one with the boss, you know how it is ;)
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James
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#5

Post by James »

Hi Andrew,

I am building one of these as well, just waiting for the last of the parts to arrive from Mouser.

What sound card do you plan to use?

Best Regards

James.
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Nick
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#6

Post by Nick »

Its huge, look at the size compaired to that car.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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Dave the bass
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#7

Post by Dave the bass »

Nick wrote:Its huge, look at the size compaired to that car.
0.33 onwards....

:-)

DTB
"The fat bourgeois and his doppelganger"
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Andrew
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#8

Post by Andrew »

I'm thinking of using an ESI Juli@, tho' I understand that the M-Audio 192 and its lower spec brethren 24/48 is quite usable as well. What about you?
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Andrew
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#9

Post by Andrew »

Nick wrote:Its huge, look at the size compaired to that car.
Yes, the book underneath is a two-man lift.

-- Andrew
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Dave the bass
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#10

Post by Dave the bass »

Andrew wrote:
Yes, the book underneath is a two-man lift.

-- Andrew
No! You're wrong my esteemed colleague.

It's definitely a book, I can see the pages from here.

This is a 2 man lift.
Image

DTB
"The fat bourgeois and his doppelganger"
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pre65
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#11

Post by pre65 »

No,no, no !

This is a 2 man lift. :wink:

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James
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#12

Post by James »

I was considering the M audio, however having looked up the ESI Juli@ you suggest it does look to be the better option, and cheaper as well!
Will have to do a deeper comparison of the specs.....
Are you going to use the audiotester software?

Best Regards,

James.
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Andrew
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#13

Post by Andrew »

James wrote: Are you going to use the audiotester software?

Best Regards,

James.
Yes, but there's also the one Nick uses, RMAA, I think?
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Nick
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#14

Post by Nick »

RMAA is great for ruining s fixed set of tests against an amp. But for investigation is no use.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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Andrew
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#15

Post by Andrew »

Nick wrote:RMAA is great for ruining s fixed set of tests against an amp. But for investigation is no use.
I had not investigated software yet, but it looks like AudioTester would be the first port of call then ;the trial version is free to download, so nothing lost.

Andrew
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