Discrete Opamp Open Design - Page 229 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th November 2012, 01:17 PM   #2281
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by jan.didden View Post
Neat! I think I need one...
Thanks for the heads-up guys!

jan
I've been evaluating the analog aspect of this, a few nits aside the biggest issue has been the response delay from the USB. You can't expect to stream two channels of 14 bits at 100MIPS to the disk.

The noise and crosstalk has been dealt with surprisingly well considering it all comes out that one bundle.

I'm not a digital guy but the logic analyser section looks like you could exercise just about any of the complicated chips that need an SPI port and a few dozen registers programmed before they do anything.

EDIT - Better idea, he might send you a free one for a one pager in the next issue.

I'll send you a contact, considering you're in the "trade" he might give you a code for the $99 US price. My code only works for 1 to an ADI address (we have had ebay issues with DSP development boards).
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.

Last edited by scott wurcer; 30th November 2012 at 01:33 PM.
  Reply With Quote
Old 30th November 2012, 05:10 PM   #2282
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Yes I could do a review.
I don't think you'd want to stream that amount of data for any length of time.
What's the internal memory - does it do block transfers?

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 30th November 2012, 06:55 PM   #2283
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by jan.didden View Post
Yes I could do a review.
I don't think you'd want to stream that amount of data for any length of time.
What's the internal memory - does it do block transfers?

jan
Yes it saves blocks of data, which limits the FFT size you can post process. I was looking for some very large (>1M) contiguous data blocks.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
  Reply With Quote
Old 30th November 2012, 07:06 PM   #2284
dimitri is offline dimitri  United States
diyAudio Member
 
dimitri's Avatar
 
Join Date: Oct 2002
Location: retired
Send a message via ICQ to dimitri
Quote:
I was looking for some very large (>1M) contiguous data blocks.
Mixed Signal USB Oscilloscope | Cleverscope
  Reply With Quote
Old 30th November 2012, 07:29 PM   #2285
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
Quote:
Originally Posted by scott wurcer View Post
I've been evaluating the analog aspect of this, a few nits aside the biggest issue has been the response delay from the USB. You can't expect to stream two channels of 14 bits at 100MIPS to the disk.
Certainly not over USB. One could wish for something with PCI or maybe even SATA (is it used for anything other than disk drives?) that would come close to that.
Quote:
Originally Posted by scott wurcer View Post
Yes it saves blocks of data, which limits the FFT size you can post process. I was looking for some very large (>1M) contiguous data blocks.
From the spec on analog inputs:
Quote:
100 MSPS, 5 MHz bandwidth, up to 16k points/channel record length
And that's a shame, as it seems that more RAM wouldn't cost very much, but at the low price point I guess they pinch every penny.

I wonder about the bandwidth, I've seen similar specs (100MSPS, 5MHz where the advertised bandwidth is substantially lower than half the sample rate) on recent model scopes, and I have to ask, why isn't the bandwidth 50MHz? Is a wider bandwidth analog section really that much more expensive? I'm missing something.
  Reply With Quote
Old 30th November 2012, 07:46 PM   #2286
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by benb View Post
I wonder about the bandwidth, I've seen similar specs (100MSPS, 5MHz where the advertised bandwidth is substantially lower than half the sample rate) on recent model scopes, and I have to ask, why isn't the bandwidth 50MHz? Is a wider bandwidth analog section really that much more expensive? I'm missing something.
We asked and got a round about answer dealing with aliasing (which is still a problem, my 100MHz fur showed up at 20MHz theoretically not possible). This was designed to sell a lot of units at the $99 price point, less than 1/2 the price of one of those tweezer meters.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
  Reply With Quote
Old 30th November 2012, 07:50 PM   #2287
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by dimitri View Post
At an absolute min. of $1,200 (without function generator), OK.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
  Reply With Quote
Old 30th November 2012, 09:53 PM   #2288
PHEONIX is offline PHEONIX  Australia
diyAudio Member
 
Join Date: Jul 2004
Location: Australia
Default USB scope

Hello Scott,

Can you clarify does this scope have differential inputs.

Regards
Arthur
  Reply With Quote
Old 30th November 2012, 10:46 PM   #2289
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by PHEONIX View Post
Hello Scott,

Can you clarify does this scope have differential inputs.

Regards
Arthur
Yes, true differential but the CMRR seems just OK.
__________________
"Greetings from The Humungus! The Lord Humungus! The Warrior of the Wasteland! The Ayatollah of Rock and Rolla!" aka the Wizard of Wrestling.
  Reply With Quote
Old 30th November 2012, 11:12 PM   #2290
diyAudio Member
 
Join Date: Nov 2011
Location: Cooktown, Oz
Quote:
Originally Posted by benb View Post
I wonder about the bandwidth, I've seen similar specs (100MSPS, 5MHz where the advertised bandwidth is substantially lower than half the sample rate) on recent model scopes, and I have to ask, why isn't the bandwidth 50MHz? Is a wider bandwidth analog section really that much more expensive?
It's almost certainly an oversampling ADC. All modern audio ADCs are oversampled and it looks like HF ADCs too.

Having a 5MHz measurement bandwidth and fs = 100MHz means you have more than 4 decades to go to -90dB and can use an easy (cheap) analogue filter. The 5MHz limit will probably be in software to match the analogue filter.

In fact, if the ADC doesn't have built in anti-aliasing, they may just let it droop to -90dB @ 100MHz. Makes it a little more useful though you can't get accurate results above 5MHz.

For Nyquist @ 1/2 fs, you need to go from 0dB @ Nyquist to -90dB in zero decades. You can't use software. That's an expensive analogue filter.

Quote:
my 100MHz fur showed up at 20MHz theoretically not possible
That's aliasing. Gotta put another 20c into the analogue filter.

Last edited by kgrlee; 30th November 2012 at 11:18 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Discrete OPAMP audio-gd Vendor's Bazaar 27 20th September 2012 04:02 PM
discrete opamp help blackpowderaudio Parts 0 16th December 2009 03:46 PM
THAT transistor headphone amp (250ma discrete opamp) design sanity check. Russ White Headphone Systems 19 13th December 2007 12:52 PM


New To Site? Need Help?

All times are GMT. The time now is 12:07 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2