recommendations for test equipment?

[TomMcNally]

You really can't measure noise and distortion with a microphone. Unless you have a high quality soundcard, like one used for professional studio work, any measurements made, even with a direct connection will be pretty poor. Keep in mind that a "Soundblaster" has about 35 cents worth of parts in the input stage. You'd be better off with an eBay obtained professional audio generator and distortion analyzer. If you are serious about building amps, the Boonton analyzer we have been using is quite a deal and really nice.

[Shannon Parks]

I think eventually that software packages and sound cards will eventually make the old hardware devices obsolete, but they'll do in a standalone device, too. In other words, some company will take a M-Audio Audiophile 192-type card and put it in a shielded box with a microcontroller and tons of connectors. Another key is a buffered input to the soundcard so that a 20Vrms input doesn't shred it. Then they'll add a USB interface and an Interface Control Document, so you can do your custom tests. Then they'll charge $10k for their effort.

Whereas you can pick up a Boonton 1120 for about the cost of an Audiophile 192. Using simple Visual Basic, you can customize it to your hearts content. For instance, Tom asked for a feature where the Boonton would 'discover' what input sensitivity was needed for 1W or 10W or ??W output. Few minutes of code later, I can enter in the power I want to see, then press a button, and the Boonton chugs away to 'find' it. Then I can press a sweep button and it will sweep at that sensitivity. Brilliant!

Shannon

[WA4SWJ]

Shannon,

Now that I'm safely in Florida I'm anxious to get my Boonton 1121 working. Any suggestions for a PC to GPIB card of some kind?

[Shannon Parks]

Shannon,

Now that I'm safely in Florida I'm anxious to get my Boonton 1121 working. Any suggestions for a PC to GPIB card of some kind?

Congrats on your move and new title, Ed!

Tom asked me about a USB-to-GPIB unit he saw on Ebay awhile back. I discounted it then, but am changing my mind. The problem is that supporting an ISA card in this day and age is almost too much trouble. Here is the link via Spark Fun:
http://www.sparkfun.com/commerce/produc ... cts_id=549

It is really a RS232 driven device using custom drivers from FTDI, the maker of the chip. I've actually used this chip at work and it works fine. The catch is that the Boonton code needs to be edited for compatibility. For example, right now the code directly calls commands from the National Instruments DLL for a write or read. This Spark Fun unit would be writing or reading through a virtual COM port.

This shouldn't be too difficult to re-code, but there might be another snafu with the unit that I don't know about. I'm going to purchase one of these in the next few weeks and give it a shot. Until then, I would just start getting together a couple BNC-to-alligator/clip cables, a couple good BNC-to-BNC cables, and maybe a female BNC-to-male RCA. You can do some measurements via the front panel which will give you a good feel for the unit.

For those that don't have a prob with ISA, then get this one:
AT-GPIB/TNT (Plug & Play)

I use the AT-GPIB/TNT that is not PNP, and I have to be careful with IRQ conflicts ala the old days. Also, there are plenty of junk GPIB cards, so be careful. There's even some old NI ISA cards that have PCI in the name - very confusing.

Shannon

[Shannon Parks]

I'm going to purchase one of these in the next few weeks and give it a shot.

I went ahead and ordered one. I'll post the results.

Shannon

[WA4SWJ]

Shannon,

Cool! If it works let me know. I'll order one too.

I've been pretty busy with the move but I should have a little more free time here. I should be able to do a few more projects per year than in the past.

[tubesman]

Try this combination: http://www.digitalaudio.com/DIGITALAUDI ... PubID=4401
this sound card has excellent performance, even the people at Stereophile love it. It's not an 1121, but it's half the price of a used 1121. That's the hardware now use this: http://audio.rightmark.org/index_new.shtml
as the FREE software to make measurements with the sound card. Total cost, less than $400. Not including the PC you already have. Hell, if you need a desktop to run the card, it still comes to less than the $950 I saw the 1121 going for. I admit the Boonton 1121 is more sophisticated but it's large, heavy, expensive and only reads audio equipment.

[TomMcNally]

I use the CardDeluxe in four systems at work (radio station) for high quality editing. I used the CardD+ (ISA) before that - in fact, I still use one here at home on a lowly Pentium 233MMX with Windows 98. The editing program - SAW Plus - can do 32 tracks on that machine - it's written directly in assembler and fits on one floppy disc !

The only issue with a PC sound card is ground loops if you are using it unbalanced, and overloading the inputs when trying to measure high power. You probably want to use an external attenuator.

[tubesman]

Those are valid concerns, I am working on an audio test station that will address some of those issues. Bottom line, if you have the cash buy a modern test box from either HP, Boonton, AP or if not, you can get 90% of the performance with 40-50% of the cash via a PC card and free software. I like both solutions for the merit they each have but I'm poor.