mrothacher said:
Mike -
That is a very viable project in these days of fast processors and affordable, high-quality sound cards. I've been experimenting with a Tascam US-122 and several software packages.
sianturi said:
Sianturi -
Essentially correct <g> - Baron Jean-Baptiste-Joseph Fourier, French mathematician, 1768-1830, known mainly for his method of analysis of periodic functions.
lumanauw said:
Lumanauw -
A distortion analyzer usually has an output that can be used for further analysis of the distortion products. That output can be displayed on an oscilloscope. The image in your message appears to be that of such a display on a dual-trace oscilloscope. The top trace is the input, and the botton trace the distortion, possibly filtered through a tuneable band-pass filter so as to display only the second harmonic. The equipment I use for such a display consistes of a Hewlett-Packard 334A distortion analyzer and a Tektronix 453 oscilloscope. I do not currently own a tunable filter but am considering buying a General Radio 1232-A tuned amplifier and null detector.
You can trim for equal current if you don't have a distortion
analyzer and the amp will still work, but the lowest figures
come from trimming with an analyzer.
The alternative is a distortionless inductor (read: air core) which
would not require such trimming.
😎
analyzer and the amp will still work, but the lowest figures
come from trimming with an analyzer.
The alternative is a distortionless inductor (read: air core) which
would not require such trimming.
😎
Nelson Pass said:
Nelson -
Hmmmm... I know plenty of sources for iron, but I suppose you'd have to wind your own air core, right? It's a pity that Morris coil winders have gotten so pricey.
You want about 1 H of inductance for wideband audio, but
if you're only going to use it for a tweeter amp, it gets a lot
easier.
The easiest way to create this air core transformer is to buy a
big roll of speaker wire. The two wires on the cable each form
1/2 of the coupled inductor that you want, and one side of one
wire is attached to the other end of the other wire to form the
center tap.
By the way, if you use air core inductors, and even some other
transformers I've tried, you want to consider some power
resistors to ground at both outputs for stability. I've seen two
examples of common-mode oscillation depending on the
particular inductor. A good value is maybe 47 ohms or so,
rated at three times the value of the idle dissipation
(the common-mode DC output voltage squared divided by 47).
😎
if you're only going to use it for a tweeter amp, it gets a lot
easier.
The easiest way to create this air core transformer is to buy a
big roll of speaker wire. The two wires on the cable each form
1/2 of the coupled inductor that you want, and one side of one
wire is attached to the other end of the other wire to form the
center tap.
By the way, if you use air core inductors, and even some other
transformers I've tried, you want to consider some power
resistors to ground at both outputs for stability. I've seen two
examples of common-mode oscillation depending on the
particular inductor. A good value is maybe 47 ohms or so,
rated at three times the value of the idle dissipation
(the common-mode DC output voltage squared divided by 47).
😎
hp-334a distortion analyzer
I just purchased this unit on Ebay. Now, can someone tell me how to use it to adjust the pots on the ZVT-7?
Hoping to hear from someone soon,
John😀
I just purchased this unit on Ebay. Now, can someone tell me how to use it to adjust the pots on the ZVT-7?
Hoping to hear from someone soon,
John😀
I beleive I've used this instrument. Many moons ago. Maybe an older version. Newer versions I think got more automatic. What does it look like. Pic? How$$
The units I used had no built in oscilator. You will need to start with a quality source. You will need to feed an input (output of amp) to it and set a ref level of 0db. There is a switdh to pull in a notch filter the notch needs to out when setting ref level. Then switch it in. The notch filter is then tuned by the giant knob on the right. The meter should drop when you are tuned to the fundamental freq. You need to critically tune the notch for the lowest meter reading you can get. You are basically filtering out the oscilator freq. The measurement you acheive is the resultant distortion and noise rms voltage... It's been a long time since I've seen one of these but that's basically what I remeber...Have fun
The units I used had no built in oscilator. You will need to start with a quality source. You will need to feed an input (output of amp) to it and set a ref level of 0db. There is a switdh to pull in a notch filter the notch needs to out when setting ref level. Then switch it in. The notch filter is then tuned by the giant knob on the right. The meter should drop when you are tuned to the fundamental freq. You need to critically tune the notch for the lowest meter reading you can get. You are basically filtering out the oscilator freq. The measurement you acheive is the resultant distortion and noise rms voltage... It's been a long time since I've seen one of these but that's basically what I remeber...Have fun
Thanks, flg.
This unit has an auto null feature. It's the top of the line for its generation (1965 or so). It's only good to 0.1 % distortion, but it's all I can afford to spend at the moment. I figure I'll turn up the amp volume to raise the distortion level to a readable point on the scale.
It only set me back $150.00.
I've been reading posts that suggest using a 1khz sinewave cd/player. It's distortion levels are supposedly quite low.
Problem is, I don't really know what I'm doing with those pots. I'll be doing a bunch of head scratching, that's for sure.
Again, thanks.
John😀
This unit has an auto null feature. It's the top of the line for its generation (1965 or so). It's only good to 0.1 % distortion, but it's all I can afford to spend at the moment. I figure I'll turn up the amp volume to raise the distortion level to a readable point on the scale.
It only set me back $150.00.
I've been reading posts that suggest using a 1khz sinewave cd/player. It's distortion levels are supposedly quite low.
Problem is, I don't really know what I'm doing with those pots. I'll be doing a bunch of head scratching, that's for sure.
Again, thanks.
John😀
Hi,
There is a Pcb at AudioXpress from Richard Crawford to make a IM Analyser
AudioXpress march 04... plus an addenda from f Glabach
I already built-it, have to finish the box....
it has 9KHz plus 19 and 20 KHz and for 40 U$PCb plus about 100U$ components
you can build a 1PPM Distortion Analyzer ; works with a analog output ...
http://www.audioxpress.com/bksprods/pcbs/testing.htm
On the other side I bought 2 old HP 332A distortion analysers last week
with the service manual for less than 200cad$ it's capable of better than 0.1%
One of them is working pretty well, the other already scrapped!
{only kept the PCb's and average components for spare parts}
regards.
Alain.
There is a Pcb at AudioXpress from Richard Crawford to make a IM Analyser
AudioXpress march 04... plus an addenda from f Glabach
I already built-it, have to finish the box....
it has 9KHz plus 19 and 20 KHz and for 40 U$PCb plus about 100U$ components
you can build a 1PPM Distortion Analyzer ; works with a analog output ...
http://www.audioxpress.com/bksprods/pcbs/testing.htm
On the other side I bought 2 old HP 332A distortion analysers last week
with the service manual for less than 200cad$ it's capable of better than 0.1%
One of them is working pretty well, the other already scrapped!
{only kept the PCb's and average components for spare parts}
regards.
Alain.
my HP-334 was DOA!
What a bunch of bs that's turned out to be--poorly packaged (one inch of wadded paper in a single-wall corrugated container), missing pieces, blackened leads on the circuit boards, scam written all over the dam_ thing. He says he'll refund my money and that I'm not to bother him or purchase anything from him again. AS IF...
Anyway, I've purchased from a different supplier a HP-332A. Does anyone have experience with this unit? I know it doesn't auto-null. What else should I know about this unit.
Hoping for the best,
John😀
What a bunch of bs that's turned out to be--poorly packaged (one inch of wadded paper in a single-wall corrugated container), missing pieces, blackened leads on the circuit boards, scam written all over the dam_ thing. He says he'll refund my money and that I'm not to bother him or purchase anything from him again. AS IF...
Anyway, I've purchased from a different supplier a HP-332A. Does anyone have experience with this unit? I know it doesn't auto-null. What else should I know about this unit.
Hoping for the best,
John😀
Sorry to hear of your misfortune. I can imagine myself doing the same🙁 So, I've been thinking of trying the modern approach. Finally got my good sound card back on line and downloaded RMAA. Cool. I'm also trying TrueAudio's RTA(free sample level). I havent got to far yet but I guess I'll try to measure and compare few of my standalone peices vs the PC and just see... The loop back testing on the card itself seems to be working😀 😀 😀
Does anyone have any experience with either of these applications? Are there other free/low cost software packages to work with your PC soundcard?
The advertising seems to indicate your sound card is the weak link of the system, but they all work??? Well, my E-Mu card can hold it's own against most and the readings I'm getting just about keep up with the card specs. I would say it's looking promissing so far...
😀 😀 😀
Does anyone have any experience with either of these applications? Are there other free/low cost software packages to work with your PC soundcard?
The advertising seems to indicate your sound card is the weak link of the system, but they all work??? Well, my E-Mu card can hold it's own against most and the readings I'm getting just about keep up with the card specs. I would say it's looking promissing so far...
😀 😀 😀
Allthough I am subscribed to audioXpress, I seem to missed the AudioXpress march 04 number with a 1ppm Dist Analyzer.
Could somebody could post a scan of the schematic of that design? . You can leave out the values to save your karma 😉
Could somebody could post a scan of the schematic of that design? . You can leave out the values to save your karma 😉
thanks for the condolences flg...
I've downloaded riaa, but I'm not crazy about the idea of routing my class A amp's voltage/current through my sound card. I suppose you could feed the amp under observation a weak signal, thus a weak output, but this seems counter productive when you want to test larger outputs.
Let me know if you discover a solution.
John😀
I've downloaded riaa, but I'm not crazy about the idea of routing my class A amp's voltage/current through my sound card. I suppose you could feed the amp under observation a weak signal, thus a weak output, but this seems counter productive when you want to test larger outputs.
Let me know if you discover a solution.
John😀
tschrama,
CI's
1 * M74HC390
1 * M74HC163
2 * M74HC393
1 * 74ACT00B
6 * NJM5532D
1 * OPA2132PA {Digikey}
1 * NJM5534D
1 * NJM7812FA
1 * NJM7805FA
1 * NJM7912FA
ALL FROM Mouser...
Alain.
CI's
1 * M74HC390
1 * M74HC163
2 * M74HC393
1 * 74ACT00B
6 * NJM5532D
1 * OPA2132PA {Digikey}
1 * NJM5534D
1 * NJM7812FA
1 * NJM7805FA
1 * NJM7912FA
ALL FROM Mouser...
Alain.
I have those pauses. They're called "senior moments". Whatever analyzer you build, there's excellent background in the Bob Cordell analyzer article- http://www.cordellaudio.com/papers/build_a_thd_analyzer.shtml The analyzer is darn good too.
You can also make an interface for your soundcard to protect it from high voltages, then use a software solution. I like Visual Analyser because it does real time spectrum analysis, octave analysis, waterfalls and many other things, plus source functions. https://www.sillanumsoft.org/
You can also make an interface for your soundcard to protect it from high voltages, then use a software solution. I like Visual Analyser because it does real time spectrum analysis, octave analysis, waterfalls and many other things, plus source functions. https://www.sillanumsoft.org/