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Old 1st April 2013, 05:34 AM   #2031
richiem is offline richiem  United States
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Richard, given that you've had driver issues with both the 0204 and the QA400, I wonder if something else is going on in your target machine? I did have driver issues early on with the QA400, but that got straightened out after some fooling around and with new software.

I still have to boot the computer and then connect and disconnect the USB plug a couple of times to get a stable connection, and I'm running XP, which should be solid now, so I can sympathize with your frustration. It is not quite PnP for me at this point, but I'm also at least one SW rev behind, now. The 0204 never gave me driver problems with XP, but maybe I was lucky -- but Creative has never made it easy to install their drivers.
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Old 1st April 2013, 08:01 AM   #2032
gerhard is offline gerhard  Germany
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I have a DG8SAQ network analyzer that mixes down to audio. Works really
well but I usually have quite some work to make my audio system function for
audio again after use.

I bought a Terratec DMX6FIRE USB as a dedicated sound system for
experiments, but had driver problems I could not resolve

So, currently I use a SNA-33 spectrum analyzer that has a 1 Hz filter
and works from 20 Hz to 26 GHz, but the sweeps are slooooow.

I was willing to buy a FFT analyzer. There seems to be no progress in
the last 20 years. Still 16 bit/100KHZ and if you want 2 channels,
BW is often reduced to 50 KHz. The useable ones still cost half
of the new price 2nd/3rd hand.

I want one that can do cross correlation and then averaging since that
brings a lot of dynamic range at the expense of time. It is always
stunning to see the noise floor drop on a E5052B.

Is there anything comparable to a SR785?

As an interim solution, I was interested into a QA400, but,
when I read here that it has driver issues, too, it is much
less appealing. One of its interesting points was that it does
not register as a sound device. :-(


cheers, Gerhard
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Last edited by gerhard; 1st April 2013 at 08:13 AM.
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Old 1st April 2013, 01:22 PM   #2033
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Quote:
Originally Posted by RNMarsh View Post
FYI update --- three spot freqs from the ShibaSoku AG15 generator -->

FREQ THD+N

100Hz .00005%
1000Hz .00004%
10KHz .000125%

The KH4402B with LT1037 for U141 and AD797 for osc U125 Opamp changes -->

100Hz .00007%
1000Hz .000045%
10KHz .00011%

Close but no cigar -- with OPA134 for U141, the 1KHz thd+n could be tuned down to .000025% or about -130dB -- 10 dB shy of goal but thd+n at 10KHz was .0005%

The wide R changes when selecting different osc freqs hurts thd+n figures.... just to keep C values low and cheaper. might be better to use larger values of C than large variations of values for R. [ yes, i know the problem with that but to get lowest thd+n requires lower R values].

The ad725d analyzer. The noise I will attempt is after the notch to see if the S/N can be improved at the monitor output port so more of the harmonics show up unmasked by noise. There is only about a 10db range for improvement. But 10dB is 10dB any way I can get it.

The input uses dozens of discrete transistors. No interest there except what the circuit design for the unbal and bal input amps are.... looks pretty impressive bit of analog design work going on. Probably done by a National Treasure with 10th degree Masters helping with it.


Thx-RNMarsh
Thanks for this data, Richard. That ShibaSoku is a remarkable piece of equipment! How much does it go for? Did you get it used?

Cheers,
Bob
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Old 1st April 2013, 05:24 PM   #2034
RNMarsh is offline RNMarsh  United States
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I dont know how much a new one costs.... but if their generator cost more than $9000 USD, you can imagine. I got it about 2.3542238721 micro-seconds after it showed up in eBay.

I called the only usa distributor -- who was hard to find... numbers changed... sounded like he rarely, if ever sold any ShibaSoku. he said he would find out about the availability of the generator for me. (?) A couple days later, said he 'could sell me one. ? They are built like a good piece of HP gear. Solid. I never would have known they existed if Demian hadnt got hold of an earlier model some time ago.

Thx-RNMarsh

Last edited by RNMarsh; 1st April 2013 at 05:40 PM.
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Old 1st April 2013, 05:33 PM   #2035
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by gerhard View Post
I have a DG8SAQ network analyzer that mixes down to audio. Works really
well but I usually have quite some work to make my audio system function for
audio again after use.

I bought a Terratec DMX6FIRE USB as a dedicated sound system for
experiments, but had driver problems I could not resolve

So, currently I use a SNA-33 spectrum analyzer that has a 1 Hz filter
and works from 20 Hz to 26 GHz, but the sweeps are slooooow.

I was willing to buy a FFT analyzer. There seems to be no progress in
the last 20 years. Still 16 bit/100KHZ and if you want 2 channels,
BW is often reduced to 50 KHz. The useable ones still cost half
of the new price 2nd/3rd hand.

I want one that can do cross correlation and then averaging since that
brings a lot of dynamic range at the expense of time. It is always
stunning to see the noise floor drop on a E5052B.

Is there anything comparable to a SR785?

As an interim solution, I was interested into a QA400, but,
when I read here that it has driver issues, too, it is much
less appealing. One of its interesting points was that it does
not register as a sound device. :-(


cheers, Gerhard
I am beginning to think the way to go might be a high speed transient waveform capture device... sample & hold... import it into a PC running DADisP or similar and process the waveform(s) for what ever you like.
Might not be able to do a lot of averaging with it... thus the thd+n requirment I have for myself.
But, enough averaging for most acoustics work would be easy to accomplish.

Last edited by RNMarsh; 1st April 2013 at 05:46 PM.
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Old 1st April 2013, 05:47 PM   #2036
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For deals see panasonic audio analyzers | eBay
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Old 1st April 2013, 06:00 PM   #2037
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by simon7000 View Post

The Panasonics are really excellent products. I have no experience with them but they should work well for amplifier tests and be reliable and the specs are very good on the best model.Might have potential for upgardes too. A lot less expensive but not a give-away, either .See thier home page for newest models and specs. Do they have FFT's?

Last edited by RNMarsh; 1st April 2013 at 06:04 PM.
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Old 1st April 2013, 06:23 PM   #2038
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This one may look familiar to you Dick. Panasonic VP-7725B | Used Audio / Distortion Analyzer | Used Test Equipment | Refurbished Test Equipment

The similarity in features and model numbers seems to indicate they are Shibasoku!
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Old 1st April 2013, 06:47 PM   #2039
dimitri is offline dimitri  United States
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AD725D

LEAVER VP-772XD
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Old 1st April 2013, 07:27 PM   #2040
1audio is offline 1audio  United States
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The Panasonic/Leaver stuff is interesting and borrows (licenses?) the ShibaSoku technology. ShibaSoku is a major vendor of video and broadcast test equipment. The audio stuff was a side trip for them in the late '80s it seems. They have a patent on the distortion analyzer part of the product. The products are not the same but similar. The 725 I have (first gen) is very similar internally to Richard's in circuits but the redesigned the unit with newer relays etc. along with newer features like GPIB control and two balanced/ unbalanced inputs.

The Panasonic worth making an effort for is the 7725B but its as rare as the 725 is in the west. Most of this stuff was used in Japanese engineering and manufacturing along with some in China (where the Panasonic stuff went to become Leaver).

The ShibaSoku box I'm after and will probably never find is this: http://www.shibasoku.com/download/avc/am51c_e.pdf It has the ultra generator and the analyzer in the box along with other features that make it more useful as a system. I don't have enough shop space for it so I'm not looking hard (and I have a budget limit of $300 for any of this stuff).

Meanwhile, I'm getting fine results and no driver problems with the QA400. I'm using with Win 7 /64 on a laptop. Since it doesn't use the normal audio interface it doesn't get "borked" by other audio processes in the PC. You need to run the latest firmware and install the current drivers. And you will need some form of interface unless you are working with mobile products.
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