Budget distortion analyzer/signal generator

[JohnRoberts]

Here's a lawyerly response from a lawyer's mouth:

"People see what they want to see,  read what they want to read, and hear what they want to hear."

As applied to me John, you seem to want to think the worst about my posts, and say it just about every chance you get.

Again and again you come up with the harshest misinterpretations of my posts that I've ever seen in over over 20 years of computer conferencing.

Since I've been on this forum, you've reserve that for me.

Which is exactly what I am doing, sharing knowledge over time.

Thing is with all the negativity, I many not be here much longer.  My story is that this forum was pointed out to me. I took a look at it and I could not believe the poor quality of the answers that some newbies were getting. Being a charitable type, I tried to give some more helpful answers without raising a fuss.  However, my answers were forcefully and illogically twisted like a pretzel.

I know that there are people who want to be the smartest people in the room, and accomplish this by driving off everybody new who arouses their paranoia.

Finding so much bad will, I'm shaking the dust off my sandals and leaving forever.



That's incorrect since any number of of my posts have been in full agreement with other posters.  Others have been factual answers to factual questions.  I obviously am not arguing everybody to the mat.  I've even agreed  with you.  However, since you are now denying this ever happened, I have learned something.

My words speak for themselves.  Your posts have been reported to us moderators several times by different members.  I even deleted one post from a member openly attacking you within one of these threads. A different mod (not me)  deleted at least one of your posts. 

I won't argue with you about what I think.

At least some of the newbie answers you think are low quality appear to be reasonable and from posters with decades of experience in the field.

I believe you could be an asset here but will stop applying negative feedback trying to help you fit in since it is clearly unappreciated. 

Good luck, I am not your problem.  :

JR

 

[ricardo]

Finding so much bad will, I'm shaking the dust off my sandals and leaving forever.

Thank you. 

 

[gyraf]

I tried to give some more helpful answers without raising a fuss

Arnyk,

If that is genuinely what you are trying to do (and I have no reason not to believe so), you should try to look closer at the ways you convey those answers. Unfortunately, the ways you phrase or build up your argumentation can often be misinterpreted as undue self-righteousness or outright trolling. As mentioned previously, several users reported your posts already - and such reporting is no common thing around here.

You may (or may not) want to work on this - yes, this world could definitely use the information you can provide - but only if you can pour it without upsetting others by wording it harshly.

To answer your next possible question: No, this type of information is not more important than the form it's presented in. In this forum, it must exist as civilized discussion, or not at all.

Jakob E.

 

[abbey road d enfer]

"People see what they want to see,  read what they want to read, and hear what they want to hear."

Stupidest argument I ever saw...only a lawier could utter that.

 

[benb]

I was a bit like this a couple decades ago when I first got on Usenet, but I somehow learned not to be this guy, and not have to correct every "wrong statement" or "wrong poster" I saw:
https://xkcd.com/386/

Quote

    not arguing every  single poster to the mat.


That's incorrect since any number of of my posts have been in full agreement with other posters.  Others have been factual answers to factual questions.  I obviously am not arguing everybody to the mat.

The earlier post of "not arguing every  single poster to the mat" was clearly hyperbole, and any reasonable person can see it as such in that context (Arny DOES tend to engage just about every post he sees as being incorrect).

But if one is going to take the statement literally, it's going to be seen as an attack and a "gross misunderstanding" and whatnot, with the results we see here.

Sorry, I don't have anything more to say about Budget distortion analyzer/signal generator.

 

[Monte McGuire]

The only thing I'd like to add is "can we talk about the circuits and gear some more?"

I value many of the unique people here, because of their deep experience and hard won knowledge, as well as their basic humanity and ability to join with others here to share their experience and hopefully push this "annoying rock up that hill" a little further than was done before.

If we can mentally "wear a tuxedo for this fancy forum" and treat it with some due respect, I think it will prove to be a gem that will improve each and all of us here, and many more down the line.

In the end. life is short, most stuff isn't so hot, but good people try to improve things, and this forum seems to be a great attempt to join the collective knowledge with the unsolved paradoxes of the participants, to try to slowly sort out this goofy field of audio electronics, and make some real advancements.

OK - pompous mode off! ;-)

 

[ruffrecords]

OK - pompous mode off! ;-)

Sounds like a pretty good summary of the people and aims of this group.

Cheers

Ian

 

[neil.johnson]

Bringing this back on topic, as an occasional weekend tinkerer I've got an HP 8903B for "roughing out" and an AP System 1 that I made a PC ISA card for, and together with a small industrial "lunch-box" PC running DOS I have myself a very useful bit of kit.  I recently saw a basic 2-channel Sys1 (but no card) go for around $300 on ebay so if you're patient you can put together a useful system for a reasonable outlay.

Neil

 

[JohnRoberts]

8903 was a rock solid old bench soldier...

JR

 

[Di_Sousa]

Attacking France marks a new low for this sub forum. 

Sorry but I couldn't resist to cool down the mood

Lately my hobby needs led me into searching on the topic of audio equipment measurement.
I read this whole thread and thank you all for the great information and advices.
Actually Arny was giving also great options in terms doing a budget but perfectly capable analyzer setup.
I feel sorry that the conversation took a wrong turn, but I'm happy it's past now.

I would like just to say that although I agree with JR in "Buy Once Cry Once" that's not always economically possible for everyone.
Also depending on your location be aware that not everyone is located in big countries, a lot of people in this forum is not from the US. We all know the US it's a huge country with a big internal market so saying that you can get the "x" unit in second hand for a great price doesn't apply to a lot of members around here.
Some members are also just hobbyists, or new into audio DIY and would prefer to spend less money for an analyser setup to understand if they would need something better.

Saying this I really would like to learn audio equipment measurements using a soundcard, laptop computer and software like REW, RMAA and Smaart. I will probably open a thread so that I and less experienced people can learn the basics.
I would like to ask members that have experience in this sort of setup and with any of these softwares packages to share info and experience.

Thank you all

 

[trobbins]

REW5 is superb for frequency spectrum, noise floor, harmonic and intermodulation distortion audio testing.  Highly recommended - but need to appreciate that reading the tutorial/help and forum information is the learning curve 'cost' of this product (given that it is freeware) even if you are just wanting to quickly check its performance.  I'm about to upgrade my $1 soundcard for a $7 soundcard to allow bandwidth increase to 40kHz for normal bench testing, but well worthwhile also having a 'good' 192kHz sampling soundcard for reference, or special tests.  Soundcard testing of electrical equipment is prone to needing diy interface to EUT, and management of hum loops if anything is somehow powered from mains, and hum ingress if not all circuitry/cabling/interfacing is screened.

 

[Di_Sousa]

Soundcard testing of electrical equipment is prone to needing diy interface to EUT, and management of hum loops if anything is somehow powered from mains, and hum ingress if not all circuitry/cabling/interfacing is screened.

Thanks for your reply.

Yes I will build a DIY interface for different impedances and attenuations, I have also some stock of transformers I could use.

Arny and Ian also talked about that in this thread:

I built a passive interface box for it that provides me with a transformer isolated signal, zero or 150 ohm terminations and 40dB or 60dB signal attenuation on the source side, and a 600 ohm load and a switched 20dB pad on the return side so I can measure distortion at high output levels.

 

[abbey road d enfer]

...worthwhile also having a 'good' 192kHz sampling soundcard for reference, or special tests. 

Unfortunately, most 192kHz soundcards do not provide much significant improvement over a 96k one for measurement purpose. S/N and THD are consistently limited by the surrounding circuitry and BW is not much different (typically about 55kHz instead of 44 for 96k)

 

[Di_Sousa]

My soundcard specs say:

Frequency response AD/DA: -1 dB: < 5 Hz - 70 kHz (sf 192 kHz)

Of course this is for the AD/DA the surrounding circuit I sure will limit the specs like you said

Anyway even 44Khz is more than enough for learning, having fun, and for most needs.

I'm really happy I've found this thread.

Thanks

 

[abbey road d enfer]

My soundboard specs say:

Frequency response AD/DA: -1 dB: < 5 Hz - 70 kHz (sf 192 kHz)

What I specifically meant was that, doubling the sample rate does not necessarily implies doubling the BW. This is true for Single and Double Speed, but for QS and 8x, not so much. That's because chip designers know there is nothing to gain in increasing outrageously the BW, for standard audio recording/transmission applications; they use the increased Shannon frequency to relax the constraints of the anti-alias and recombining filters, which is unquestionably beneficial to the sound quality.
RME constitute an interesting exception; the HF response in 192kHz goes up to 90+kHz; at 384kHz, it is somewhat different; Chapter 34.17 of the ADI-2 Pro manual explains they have included the possibility to run their 384k converters with a complementary EQ that linearizes the frequency response closer to the Shannon frequency (135kHz -3dB point instead of 115kHz).

 

[trobbins]

My cheap secondhand e-mu 0404 is likely to have the same as the 0204 model that Virtins tested in 2011 for a 92kHz -3dB bandwidth at 192kHz sampling, and -115dB'ish floor, so it suits my need for anything more special than a $ USB soundcard.

 

[abbey road d enfer]

My cheap secondhand e-mu 0404 is likely to have the same as the 0204 model that Virtins tested in 2011 for a 92kHz -3dB bandwidth at 192kHz sampling, and -115dB'ish floor, so it suits my need for anything more special than a $ USB soundcard.

I don't deny that many soundcards offer plenty in terms of performance; I was just warning that one must not assume that doubling the SR automatically doubles the BW, or that each additional bit of resolution increases the dynamic range by 6 dB.

 

[AusTex64]

One thing I've learned about audio measurements is how much loading affects the device under test, especially if it's a 600 ohm device that uses transformers. My QA401 is 100K ohms load/out and 47 ohm source/in. So even with a 10K input/50 ohm output device, I'll get slightly different levels and THD with the 100K  ohm load than with a 10 K load (I've made adaptors to get 200 ohm, 600 ohm and 10K loads.  Loadng a device with 600 ohms source is the hardest test for an output, I think the worst case scenario.

Proper measurement is an art unto itself, and I still have lots to learn.

 

[abbey road d enfer]

One thing I've learned about audio measurements is how much loading affects the device under test, especially if it's a 600 ohm device that uses transformers.

One should not forget that the impedance of a transformer is essentially variable. It varies with frequency and level, and also depends very much on how it's connected. The most misleading thing is assuming a transformer rated at 600 ohms will measure at 600 ohms unconditionally.

 

[ruffrecords]

One thing I've learned about audio measurements is how much loading affects the device under test, especially if it's a 600 ohm device that uses transformers.
Proper measurement is an art unto itself, and I still have lots to learn.

As a rule, distortion increases as the output power increases. With a given load, this usually means distortion increases in direct proportion to output voltage. However, the easiest way to achieve a very impressive distortion figure is to measure it with a high impedance load as this represents a very small power even at a high voltage (marketeers are fully aware of this). Repeat the test with a 600 ohm load  and watch the distortion rise. Neve 600 ohm balanced outputs were rated at +26dBm into a 600 ohm load which is 400mW of power.

Cheers

Ian