What's on your workbench???

Hi Jan

The NOISE FLOOR System One from a few years ago

Hi Udok

The noise floor of the System One can be improved by changing the NE5534 with AD797. The compensation must be changed. I have only had one system that didn't have a noise floor improvement, typically 2 dB the best has been 2.7 dB.

FYI: The Generator output stage are the same for Sys1, Sys2, Sys2c & 2700.

I repair / service System One

If you want more info Email me
Duke
 
I hated working on mixers, back in 1990 I was working part time at a guitar shop where I did repairs. Someone brought in a 24 ch Roland mixer (like attached) it had some mashed volume sliders.To take it apart you have to remove the top first. All of the knobs and nuts and washers on all of the rotating controls. Well over 100 closer to 200.
 

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Under my bench

Take a look.
This mounts under my bench to hold the computer keyboard and mouse. Easily accessible, easy to slide out of the way.

I got mine new surplus on ebay.

Thanks DT

Humanscale
 

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Audio Precision System one

Jan, I am on my second iteration of reducing THD in both the generator and analyzer.

I have put and shall be putting a a large amount of time into this.

Once I have completed a full new modification I shall make a decision on whether to give it out.

The only way that I would feel comfortable charging a fee for my work will be if there is a serious improvement over my first modification effort.

My 5 System One's exhibit slightly different readings and so I have chosen the best of them to use as a mule

Steve Mantz
Zed Audio
 

I was interested and got two variations. both are pretty nice with spaces for managing parts etc. the smaller one is best suited for cell phones and similar tiny stuff. The larger is pretty practical for audio scale PCB's.

However the claims of antistatic don't hold. I tested both with the 3M tester and they both failed completely. I verified with standard antistatic mats that the instrument was working correctly. If you are in a high humidity area and the parts are not real sensitive it won't be an issue. but you have been warned.
 
Jan, I am on my second iteration of reducing THD in both the generator and analyzer.

I have put and shall be putting a a large amount of time into this.

Once I have completed a full new modification I shall make a decision on whether to give it out.

The only way that I would feel comfortable charging a fee for my work will be if there is a serious improvement over my first modification effort.

My 5 System One's exhibit slightly different readings and so I have chosen the best of them to use as a mule

Steve Mantz
Zed Audio

I did some tests with bridging the CMOS switch which selects any or none of the pluggable internal filters. These CMOS switches (CD4053 in this case) are known to be nonlinear; the 'on' resistance varies through the signal cycle, so depending on the load impedance, generate distortion.

The residual 3rd at the 2722 did drop a bit over 1dB, consistently. Not as much as I had hoped.

There are a few more of these CMOS switches in the Reading circuitry area but I haven't found out what they do and what the signals and levels are.

As for replacing the opamps in the S1 with AD797s, I attended a presentation by Bruce Hofer for the Netherlands AES section several years ago and IIRC they used 47pF as comp cap for those 797's.

Jan
 
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Jan, I am on my second iteration of reducing THD in both the generator and analyzer.

I have put and shall be putting a a large amount of time into this.

Once I have completed a full new modification I shall make a decision on whether to give it out.

The only way that I would feel comfortable charging a fee for my work will be if there is a serious improvement over my first modification effort.

My 5 System One's exhibit slightly different readings and so I have chosen the best of them to use as a mule

Steve Mantz
Zed Audio

Steve,

Myself as well as others here would be very interested in how far you can push the old AP System One's performance. Keep us updated as you progress.
 
AP

It will take me another 4 months as I am tied up with a massive design project.

This amplifier project requires an gen/analyzer with lower THD than System One can do and that is why I am doing this.

I shall post once I have completed the AP

Thanks for being patient all.

Steve Mantz
Zed Audio
 
I've moved with my hubby to new digs. The new place has a home theatre room, plus study, four bedrooms and activity room. It's frankly ridiculously big for just the two of us.

So I've taken the home theatre room (4m x 6m) as my study and test equipment area. The room is open plan onto the entry-way and living areas, so I'll have to keep it tidy.

As well as that I've commandeered the study room (3m x 4m) as a sewing/soldering room, as it's just across from my actual study so it's convenient. Perry's grabbed one of the bedrooms as his man cave (somewhere he can display his thunderbirds toys). We've also got a guest bedroom, a gym room, and (I kid not) we're using the activity room as a library.

So all our bad scifi and fantasy novels and DVDs come out of their hidey places in various boxes and get displayed in bookshelves. It's rather nice.
 
Hi Suzy,
That sounds amazing! What a nice space to work in. I'm hidden away in our basement. Of course, it's cool in the summer (cold if the air is on) and warm in the winter. It must be really nice to be able to look out of a window while you're working on a tough problem. Congratulations!

As for the house size ... you two earned it. It sounds like a sweetheart of a house.

-Chris
 
New house, new workbench. I just finished making the huge solid Karri bookcase in the background, so figured it was time for a photo. I’ve evicted construction activities to my “sewing and soldering” room, which is still a schemozzle, but it means my main study is reasonably uncluttered. I’ve got my HP3585B spec an and HP3325B sig-gen, plus a Tek TDS340A. I’m partial to Thurlby lab power supplies - I’ve got a dual PL320 and a PL154. I’m using a Fluke 87 DMM as well. I’ve got a Frex AN67 high purity source under the spec an for when I need a good 1KHz tone. The microscope is a Nikon 645 stereo one, and will be evicted to the soldering and sewing room once the bench in there is adequate. Out of shot to the right is my iMac. Behind me is my main stereo (NAD) which I listen to while I work.

I’ve gotten on top of the test lead problem by using many clip-close plastic bins - one for BNC leads, one for RCA leads, one for adapters, one for cro probes, etc.
 

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