I built a DSO138 "oscilloscope" kit and found it to be a nearly useless toy link to diyAudio post. Its triggering is terrible and its bandwidth in practice, is a lot less than the claimed 0.2 MHz.
"Original JYE Tech DSO-SHELL DSO150 15001K DIY Digital Oscilloscope Kit With Housing"
https://www.banggood.com/Orignal-JYE-Tech-DS0150-15001K-DSO-SHELL-DIY-Digital-Oscilloscope-Kit-With-Housing-p-1093865.html?rmmds=search
George
Bargains are nice, but next to useless to make better audio designs. Either you guys are very, very poor, or you have little interest in audio design to take such a 'toy' oscilloscope seriously.
For example, when I was young, in 1962, I built an EICO 5MHz oscilloscope kit that cost me $100 at the time and took lots of time to put together. Now, it was not in any way perfect, BUT it appears to have run rings around these 'toys' that you are discussing. Of course, when I was introduced to TEK scopes through work and friends, I put my EICO aside, but it was at least 'useful' for several years while a student. These 'toys' remind me of my first digital camera that I bought at Radio Shack. Next to useless.
For example, when I was young, in 1962, I built an EICO 5MHz oscilloscope kit that cost me $100 at the time and took lots of time to put together. Now, it was not in any way perfect, BUT it appears to have run rings around these 'toys' that you are discussing. Of course, when I was introduced to TEK scopes through work and friends, I put my EICO aside, but it was at least 'useful' for several years while a student. These 'toys' remind me of my first digital camera that I bought at Radio Shack. Next to useless.
I'm still lost on the phase linearization thing. Attached are some plots of a not special headphone. The nominal measurement level was 90 dB SPL. Selected because the distortion was around .1%.
First a 50 mS waterfall. The vertical is around 40 dB. You can see the decay at low frequencies and the power line artifacts. And that there is no real info here.
Second is a 2 mS waterfall. This is more conventional and shows the stuff you would look for to improve the driver (and housing in this case).
Third is the time domain response (impulse response) that the waterfall was derived from.
Finally the amplitude and phase response, Decidedly NOT flat.
Attachments
I'm using headphones because they bring their own quasi-anechoic environment with them. If I can find a noise cancelling headphone i'll try that as well.
Here is another headphone with a different phase and frequency response. What should we see as an artifact?
Here is another headphone with a different phase and frequency response. What should we see as an artifact?
Attachments
Some discussion of phase linearization here: The Arion/Essex Acoustics Digital Loudspeaker Correction System:
Also, believe Hawksford wrote an AES article on the subject, but I don't have a link.
It has to do with how nice impulse responses look, and maybe waterfall plots too (possibly those produced by FFT processing of the impulse). However, waterfall plots can also be produced with bursts of sin waves, so at least no issues with possible FFT artifacts that way.
Also, believe Hawksford wrote an AES article on the subject, but I don't have a link.
It has to do with how nice impulse responses look, and maybe waterfall plots too (possibly those produced by FFT processing of the impulse). However, waterfall plots can also be produced with bursts of sin waves, so at least no issues with possible FFT artifacts that way.
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A good driver will not show many resonances and all freqs decay fast and at same rate.
Such as this ---
Question? do we measure speaker response or response in listening room with a microphone placed at the ear drum of a dummy head/ear?
We shouldn't do it with headphones either. Unless, they are in-ear type.
THx-RNMarsh
Such as this ---
Question? do we measure speaker response or response in listening room with a microphone placed at the ear drum of a dummy head/ear?
We shouldn't do it with headphones either. Unless, they are in-ear type.
THx-RNMarsh
I went through my library of measurements and found good examples to show the difference between how a phase corrected speaker measures against one that isn't (not the same speaker).
The left corner cannot be trusted (what else is new?).
Although the measurement of the linear phase speaker might look cleaner, it is quite shitty as a matter of fact in comparison to the minimum phase speaker.
Measurements were both done in the same anechoic chamber, albeit at different times.
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Professional work Frans! Chapeau!
How do you like your Keysight muiltimeter with all the extra feautures? I was just looking at it yesterday.
Can you disclose the retail price of the power amp?
Jan
Wrong thread?
I do object to 'grotesque'
but I would accept 'over the top' and 'at the limit of acceptable'. For me it is just what I think is the maximum possible in construction and implementation and one day there will be a matching preamp (you know) Edit: Ooops I see, it is to answer Jan's question
Edit: 15k parts, labor and development
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Thanks
I love it to dead, and when it is (dead) I will get a new one. The instrument is build to a high quality standard and may never need replacement (in my life time).
52000
P.s.
One thing I do with the Keysight is measure totalized noise, offset and offset drift. These measurements run over long periodes at the maximum resolution of the instrument. The result is this (see picture) Gaussian curve, this one (after 15000 measurements, about 7 hours) shows a spread of (max) 20uV (I guess about 5uVrms). All amplifiers are tested in this way before leaving final assembly, if the base of the curve is not wider than 25uV the amplifier is acceptable
https://flic.kr/p/DTWLTd
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