Using the Panasonic VP 7725 Audio Analyzer
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- čas přidán 7. 09. 2024
- Some subscribers have expressed an interest in a deeper look at this unit, so I made this video. Please ask in the comment section if there's anything else you'd like to know about this tool.
Wow, this is really good information. My budget won't allow for one, but maybe a Keithley and external oscillator some day.
Great video, thanks!! Your explanation of needing a terminator answers my question about why I saw double the voltage when I plugged the input to the output. And the bit on the isolated ground helps too… I wish my scope had a fully isolated front end. I sold the extra fully functional one to Ben at Novalux Stereophonic, who also has a CZcams channel and maybe it will be featured in one of his videos some day. He seemed really interested in that extra set of BNCs on the back which apparently show just the distortion on a scope (and even connected it in X-Y mode). I’d love to learn more about how that works/what use it has one day.
I use the Rolls HE18 Hum Eliminator to connect the dummy loads to the scope, and it will provide isolation.
The BNC's on the back don't show residual distortion, but rather shows the input before processing. Page 45 on the PDF.
@@raygianelli3612 thanks for the tip on the Rolls! Yeah I saw that in the manual, but it makes it sound like the “input monitor” and “reading monitor” are more or less the same thing, no? If you connect a scope to the reading monitor it seems to give a totally funky signal that changes with the amount of distortion present
I checked out the Rolls device, looks like it’s just some audio isolation transformers in a nice box - I just found a use for the pile of small audio transformers I got in an estate sale. Thanks again for sparking some great thoughts!!
@@philsanalogbasement That's exactly all the Rolls is. Sounds like you've got everything you need!
Thanks Ray very interesting. I have the Keithley and have to use an external freq/oscillator but apparently saves me more money then I can justify for my hobby. Love your vids please keep them coming.
Thanks Mike. More on the way!
Hey Ray I am not sure if i mentioned this to you. The issue you mentioned with the isolation ground being defeated by connecting it to a scope thru the rear monitor output of the 7725 in this video, I found if i use a set of BNC isolation baluns between the monitor out and the scope i can pass the signal thru to the scope adequately and isolate both the ground and signal between and resolve this issue and still keep the scope and the 7725 earth grounded. One drawback though that cannot be defeated is if you are testing a stereo amp that has a hot negative and positive signals that the input ground on the 7725 is all tied together so there is no way to test amps like this driving both channels at the same time. You would only be able to do one channel at a time. trying to use a balun like this on the input side will interfere greatly the ability to read both levels and THD properly though i havent actually tried this but i assume it would have that affect.
Excellent Ray! I want one.
Well, the good news is that they seem to be able to be found way cheaper than when I bought mine!
@@raygianelli3612 Nice!
I us d a 8903 Audio Analyzer at work for 25 years. I would love to have one at home.
Hadn't looked at them lately, but they used to be available for a few hundred. I'm sure that's changed. I liked that you could set it up to sweep a range of frequencies.
Love it! Thank you. Im currently looking into a AD-1 amp dyno. I have resistors and siglent 4 channel 1104xe. I really just want an all in one unit.
The AD-1 looks pretty impressive. So does the price tag. IMO that kind of expenditure only makes sense in a production environment. And TBH I think you'd gain a better understanding of measurement procedures using various units as most of us do. But at the end of the day if you have the disposable income and you want it go for it.
@@raygianelli3612 im not opposed to any other audio analyzers. I would use the AD-1 to make money and it does mostly what anyone wwants to know about their power ratings on their amplifier/distortion IHF certified and uncertified. Just like a car dyno. Same mentality i guess.
I have the 7725D also. I had it on my eBay search list for a LONG time. One finally showed up that looked like a good unit. I offered $900 for it and he accepted my offer! Obviously, I was skeptical about the condition but it is in great physical condition and works great.
I didn’t catch the name of the cables you mentioned. What brand are they?
LOVE your videos! Im always excited when I see a new one has been posted.
Bill, I found some Westek BNC to BNC cables at work for a piece of equipment that was no longer used. I cut them in half, and put some Neutrik RCA ends on them. The Neutrik's were about $10 each, but very good quality.
Thanks for the kind words, more videos on the way!
I picked up the VP-7725B today but am having a hard time finding a user or service manual. Any change you have either of those Ray?
Wil, send me an email and I will attach what I have. If you click ...more next to my channel description you'll see my email.
Hey Ray.. Great Video, and as always very informative… What are you thoughts on the the QuantAsylum Audio Analyzer (QA-40x) and/or the Digilent w/Audio Analyzer suite, as an alternative to the VP 775d..? You mentioned that your VP 775d cost quite a bit.. Is it worth hunting down? Or (for the money), is the QA or Digilent solution just as good..? Thanks for what you do…
As always, the answer depends on your application and budget. IMHO the Quantasylum is the best bang for buck out there, and I probably would have gone that route if I had it to do all over again. But the Panasonic lets me test both channels at once, which is how most amps are rated, so that's a plus. And I've thought about used Audio Precision gear too.
The Digilent Pro series looks good but is also not cheap.
Basically the law of diminishing returns applies here in spades. If you want low distortion measurement capability be prepared to pay.
Thanks for your input Ray.. Much appreciated..😊
@@esci8978 Let me know which way you decide to go. Always nice to have input from someone who owns a piece of test equipment.
@@raygianelli3612 I have an opportunity to pick up a used Digilent Analog Discovery 2 for half the cost of new… So I think i will get my feet wet with that.. I know It won’t measure no where near the low distortion levels of the Panasonic, but for the little cost, it would give me the opportunity to learn.. Moving forward from there, I’ll wait to see what opportunities are out there to acquire something better, like the QuantAsylum product….As nice as your Panasonic is, I like being able to have the visual representations of what the combination computer screen/QuantAsylum type equipment offers..
@@esci8978 That makes sense. If you are able to get something cheaply you can always get your money back should you decide to upgrade in the future. Best of luck on your journey!
Once again great information. I have attempted to work around the Keithley's issues by purchasing "Ultra Low Noise Oscillator boards, a 1 Khz and a 10 Khz. Currently my biggest issue is the inability to purchase a Quant Asylum Q403, since they are not shipping due to a fire. You had also mentioned a software alternative "Visual Analyzer", I did download and installed it connecting it to a very good USB based sound device (Scarlet 2i2 3rd Gen). However, the initial setup and calibration of "Visual Analyzer" has me stumped (The only documentation I could find is in Italian).
Would you consider a short video demonstrating the set up and use? I am sure many of us would really appreciate it since that may be the best solution for those of us doing this as a hobby. Thanks again for the time you take to share your knowledge.
For anyone interested in information about the Oscillators I mentioned, here is a link. I am in no way associated with the maker; I am just providing this in case it can help others. I originally found the information on AudioKarma for "Victor's Oscillator", here is a link to a detailed description. archimago.blogspot.com/2022/01/using-victors-oscillator-as-reference.html
James, I will at some point do a video on setting up and using Visual Analyzer. Thanks for the suggestion!
Great video as usual Ray, thanks for sharing. Did you happen to run the oscillator output from the Levear into the 2015 to see how low it measures on the 2015?
Yeah, while I have done that I didn't think to do it for the video, as I was focused on the Panasonic. The Keithley measurement section works very well.
I actually used a sine wave created in Audacity and played on a CD player, which yielded better THD than the 2015's generator.
@@raygianelli3612 Thanks again Ray, I was wondering how low of distortion you can get out of a good audio interface and a PC. So, a decent audio interface and a 2015 might be a decent solution for some at a reasonable cost.
@@toddhoug9713 Todd, the limiting factor is the THD of the interface itself. The last time I checked the Focusrite Scarlett looked to be the best for low THD. Some manufacturer's don't list the THD, or some list chipset performance, which may be different installed in their product.
I've used the Alesis IO2 and the Behrninger U202 with Visual Analyzer with good results.
Ray Gianelli Panasonic VP 7725 Audio Analyzer Where can I get it
Depends where you are. They're harder to find in the US than in Asia. But they are available in either place. They're usually not cheap.