Keith Johnson showed me a VW microbus that did the same thing 25 years ago. We all thought they were a hoot. Cost around $30 then. Way pre Bluetooth.
Sent from my LG-H811 using Tapatalk
Sent from my LG-H811 using Tapatalk
Just for fun, why not ?.....
Yeah I've heard about them, nasty but fun just like those thin flexible transparent 45's that came with magazines, newspapers, corn flakes etc.
BTW what happened to those little clip together toys that were buried down the bottom of the cereal box....taught me things like visualising assembly of parts and even Newtonian physics.
soundwagon-record-player
SOUNDWAGON Instructional Video
2015 update - the-soundwagon-is-dead-long-live-record-runner
Ok, back to the subject at hand, interesting as always around here.
Dan.
Yeah I've heard about them, nasty but fun just like those thin flexible transparent 45's that came with magazines, newspapers, corn flakes etc.
BTW what happened to those little clip together toys that were buried down the bottom of the cereal box....taught me things like visualising assembly of parts and even Newtonian physics.
soundwagon-record-player
SOUNDWAGON Instructional Video
2015 update - the-soundwagon-is-dead-long-live-record-runner
So, in hipster heaven old is new again, the difference is hipster cool laser cut bamboo enclosure, Bluetooth and the claim that 'fine balancing' reduces record wear, ya just get the crowd to stump up the development costs for an essentially useless toy....woteva.
Ok, back to the subject at hand, interesting as always around here.
Dan.
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Needle, cheapest phono cart you could find, the stylus is the 'steering wheel' as per the video I posted.
Audiophile versions/upgrades ? lol.
Dan.
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noise maker I can remember as a kid, many years ago, recording onto one of those vinyl discs. I formed a small paper horn and stuck a needle through the end and spoke or shouted into the horn like Edison while holding it onto the spinning vinyl. Replay just required sliding the needle into the groove.
Yes finally.
Here are my measurements at the output of my 2x4MiniDSP.
First attachment: The freq response rel 1KHz from the two biquads in isolation (in blue the theoretical RIAA curve)
1st biquad (48KHz) coefficients:
-13.73dB (RIAA)
poles = [2112.13558715, 33306.8973142]
zeros = [17945.9351038, 41551.3073517]
a coefficients = [ a0=1 a1= 0.3860447 a2=0.28092631]
b coefficients = [ b0=1 b1=0. 54257034 b2=0.03711006]
Gain at 1kHz = 12.6531891507 dB
2nd biquad (48KHz) coefficients:
50.05 Hz and 500.5 Hz (RIAA)
poles = [27000.4683709, 50.0497911677]
zeros = [27003.1704285, 500.320253393]
a coefficients = [ a0=1 a1=0.71622826 a2=0.27543121]
b coefficients = [ b0=1 b1=-0.659297 b2=-0.25970356]
Gain at 1kHz = 0.705745669113 dB
Second attachment: The freq response rel. 1KHz of the resulting dual biquad (48k) RIAA (the two above biquads cascaded) and the error.
Third attachment (for comparison): The freq response rel. 1KHz of the single biquad (48k) RIAA and the error.
Single biquad RIAA (48KHz) coefficients:
poles = [52.5257285337, 2287.22026941]
zeros=[21833.6972506, 536.805364274]
a coefficients = [ a0=1 a1=1.73273489 a2=-0.73451925]
b coefficients = [ b0=1 b1=-0.75549731 b2=-0.16463057]
Gain at 1kHz = 13.16179286 dB
Forth attachment: The phase response of the two (single and dual biquad) RIAA implementations.
Fifth attachment: Measurement setup (*)
Errors of both -all digital- RIAA implementations are within the limits that Scott has mentioned in his LA vol. 10 article.
The dual biquad RIAA having ridiculously small error wins the competition.
All the coefficients shown above, have been copied from Jan’s site download section with no other change except from the sign reversal of the ‘a’ coefficients.
https://linearaudio.net/sites/linearaudio.net/files/v10 sw app1 table a-1.xlsx
https://linearaudio.net/sites/linearaudio.net/files/v10 sw Appendix 1b web.docx
Once again, thanks to Scott for all the work and to Jan for publishing and hosting it.
(*) The description of how I performed these measurements is to be found in post # 294. The procedure is exactly the same, I only have lowered the resolution (652 data points per measurement)
George
Attachments
Yes, the insignificant drop (-0.09dB at 20Hz, -0.016dB at 10Hz, -0.037dB at 5Hz) most probably is due to the imbalance btn the hardware of the two channels of the measurement setup chain (soundcard+2x4MiniDSP).
The results shown are R channel (RIAA eq) minus L channel (flat) because the intent of the exercise was to test the performance of the algorithms and the DSP part of the 2x4MiniDSP only.
This means that the hardware constrains common to both channels like low freq and high freq roll off don’t show up except when there is some small difference btn the hardware of the two channels.
In actual use, the operation will not be R channel minus L channel, therefore the frequency roll-off due to hardware will be as expected more pronounced:
2x4MiniDSP:-0.27dB at 20Hz, -0.56dB at 10Hz, -2.38dB at 5Hz)
Soundcard: -0.21dB at 20Hz, -0.48dB at 10Hz, -2.11dB at 5Hz)
Attachment: Testing 2x4 MiniDSP.
Gain structure is THE important point which may affect MiniDSP 'sonics'.
From post 24 and on:
http://www.diyaudio.com/forums/minidsp/230470-signal-level-minidsp-x-over-3.html#post3412698
George
The results shown are R channel (RIAA eq) minus L channel (flat) because the intent of the exercise was to test the performance of the algorithms and the DSP part of the 2x4MiniDSP only.
This means that the hardware constrains common to both channels like low freq and high freq roll off don’t show up except when there is some small difference btn the hardware of the two channels.
In actual use, the operation will not be R channel minus L channel, therefore the frequency roll-off due to hardware will be as expected more pronounced:
2x4MiniDSP:-0.27dB at 20Hz, -0.56dB at 10Hz, -2.38dB at 5Hz)
Soundcard: -0.21dB at 20Hz, -0.48dB at 10Hz, -2.11dB at 5Hz)
Attachment: Testing 2x4 MiniDSP.
Gain structure is THE important point which may affect MiniDSP 'sonics'.
From post 24 and on:
http://www.diyaudio.com/forums/minidsp/230470-signal-level-minidsp-x-over-3.html#post3412698
George
Attachments
George, you really have done all the homework to make it easier for the rest of us.Thank you I am embarassed to admit my miniDSP has been gathering dust for 2 years now. Mainly because i made the false economy of not spending $130 on the official case for it and thinking I could mod something I already had, whilst dealing with a full time job and 5 kids. That was dumb of me.
Bill
Beauty is in the eyes of the beholder of course but if you manage to surpass me in housing ugliness and shamelessly turn a temporary test set into the main element of a more or less continuously evolving audio 'system' (my excuse: life is short), I’ll eat my hat 😀
http://www.diyaudio.com/forums/minidsp/238892-my-stack.html#post3554127
George
That actually looks rather neat (to me). I meant there are knobs and labels. My current pre-amp has one so I can remember which is volume. I'll try and and remember to take a picture. Sadly no evidence left of the OTL amp a friend and I build on a piece of wood, or the tube PSU in a cardboard box. Silly me, we all know baking trays are best for prototypes 🙂.
Well ordered the proper 2x8 box last night so lets see where we go. Looking at your stack I think I see a ministreamer in my future. I've worked out most of the setup I need, the only annoyance is will still need an analog signal routing setup to switch between vinyl and the home theatre.
Right back to kitchen. Wife is not feeling well (for once ACTUALLY my fault) so all inedible food tomorrow I can take the blame for 🙂.
Well ordered the proper 2x8 box last night so lets see where we go. Looking at your stack I think I see a ministreamer in my future. I've worked out most of the setup I need, the only annoyance is will still need an analog signal routing setup to switch between vinyl and the home theatre.
Right back to kitchen. Wife is not feeling well (for once ACTUALLY my fault) so all inedible food tomorrow I can take the blame for 🙂.
Whilst still debating how to fit the kenwood into the listening area I am still mulling about how to do the amplification. So many things to consider. Now as I think I have previously mentioned I think the Bob Cordell method of loading down the cartridge to provide at least some of the HF roll-off has a certain charm. Looking through the LA archives I discovered that Bob is not the first to examine this in the magazine and in fact Steven van Raalte did an article in volume 3 which went a step further and introduced an 'inverse resonance filter' to deal with the mechanical resonance that is put into most MM cartridges to lift the high end. Now whilst Grado owners can be smug at this point, the filter Steven looks at is an analog biquad so is a perfect candidate for implementing in MiniDSP. What I haven't got my head fully around is the noise penalty Bob talks about with using the damped method to implement the full 75uS equalisation. Ideal would be to have a cartridge that doesn't use these helper resonances (again stop being smug Grado owners) but getting to that is a seperate discussion for another thread which I am working on...
Maybe not ! Anyway, if someone has valuable tech contributions to make, what's the problem ? None as far as i'm concerned 😉
It was just a bit of a shock when I clicked home to get to the digital RIAA article. The combination of dry tech articles, his claims in his resume of the book and the comment on capacitor sound make me happy to read his articles, but not to want to be sat next to him on an aeroplane!
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