0.3mv at 3.54cm/sec, simply means (5.0/3.54)*0.3mV = 0.42mV at 5cm/sec.
Playing the 1Khz track with 60dB gain should give 0.42V or -7.5dB, not the -27.11dB in your picture, unless you have attenuated the signal by 20dB with a volume pot ?
But overlaying the above image with the .wav file you sent me, the ratios between all harmonics are the same !
Hans
Playing the 1Khz track with 60dB gain should give 0.42V or -7.5dB, not the -27.11dB in your picture, unless you have attenuated the signal by 20dB with a volume pot ?
But overlaying the above image with the .wav file you sent me, the ratios between all harmonics are the same !
Hans
Attachments
So simple, thanks!
For the rest, at the moment I have no explanation. I also always get the same tdh ratio whatever gain or preamp I select.
This ortofon lp also gives lower sound level when played through speakers and listened by ears. Signal was surely not autenated, as there is no potentiometer in measurement signal path.
For reference there is real music record I sent you, that peaks all over. Suspecting that test record is actually crap.
Nevertheless the tdh and noise level of this LP played with chart is consistently and comparably measured horrible (noise of empty tracks not so bad actually).
Yet music played through this system and real records has (subjectively) so much space, depth and presence of music being inside the room than any digital recording... Before this exercise I was not aware how misterious this is
It's really great to see this work with the Ortofon record going on. It can be informative to use the different tracks to ensure everything is aligned properly. The Left and Right channel only tones are interesting to look at the cross talk. The tracking tests at different levels eventually show some wave form distortion.
Audacity worked really well for me to capture recordings. I made these recording with my linear tracking Technics SL-Q5.
I captured the sweep signal using a flat preamp, no RIAA EQ at all. I applied EQ using Audacity.
I used 9 dB/octave as shown above. I think it should have been 10 dB/octave, according to this post I found below.
"
P.s. I forgot to say that within Audacity you will have to construct an upwards going 10dB/dec eq filter from 300Hz to 30Khz or so, to rotate the spectrum from 10dB/dec downwards going into a horizontal one. Once made, it will be a hit of a button in Aadacity to apply the filter.
"
That yielded the following result that looks very flat.
I also captured audio from the tracking tests.
Below is the 50 mm/s tracking test. 315 Hz 50 um peak waveform. 2nd Harmonic is -46 dB (fundamental is 1.6) or 0.5% distortion.
Below is the 60 mm/s waveform with a small visible distortion in one channel.
I started seeing large wave form distortion at the 70 mm/s level
Audacity worked really well for me to capture recordings. I made these recording with my linear tracking Technics SL-Q5.
I captured the sweep signal using a flat preamp, no RIAA EQ at all. I applied EQ using Audacity.
I used 9 dB/octave as shown above. I think it should have been 10 dB/octave, according to this post I found below.
"
P.s. I forgot to say that within Audacity you will have to construct an upwards going 10dB/dec eq filter from 300Hz to 30Khz or so, to rotate the spectrum from 10dB/dec downwards going into a horizontal one. Once made, it will be a hit of a button in Aadacity to apply the filter.
"
That yielded the following result that looks very flat.
I also captured audio from the tracking tests.
Below is the 50 mm/s tracking test. 315 Hz 50 um peak waveform. 2nd Harmonic is -46 dB (fundamental is 1.6) or 0.5% distortion.
Below is the 60 mm/s waveform with a small visible distortion in one channel.
I started seeing large wave form distortion at the 70 mm/s level
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I compared your music fragment to the 1Khz test tone.
When I got you correct, the 1Khz test tone was amplified by +10dB additionally to the already available 60dB.
However the Music was amplified by just 60dB.
So, I attenuated the 1Khz by 10dB, to make it directly comparable in level to your music fragment.
Quite obvious is that the music fragment is much louder and clips all the time, so much for extra headroom for overload !
Hans
Attachments
Hi Hans,
Now you see what I see too, you did not have to reduce 10db at 1khz signal, it would still be quieter than music... That's my head scratching about ortofon record.
Music record is clipping, sure, I also see that. But consider that recording gear (soundcard input and ADC) has only few volts DC of PS to deal with that signal.
Preamp has anything between +-12 and 18V to deal with it, they should not clip I think... What we see on these tracks is soundcard input clipping. I'm sorry I have no ADC gear to record say 12 V peak to peak....
Now you see what I see too, you did not have to reduce 10db at 1khz signal, it would still be quieter than music... That's my head scratching about ortofon record.
Music record is clipping, sure, I also see that. But consider that recording gear (soundcard input and ADC) has only few volts DC of PS to deal with that signal.
Preamp has anything between +-12 and 18V to deal with it, they should not clip I think... What we see on these tracks is soundcard input clipping. I'm sorry I have no ADC gear to record say 12 V peak to peak....
Drbulj,
Could you feed your 60dB phono amp with a 0.42mV sweep signal from REW from 1Khz to at least 20Khz or even higher, this being equal in level to 0dB at 5cm/sec.
This will calibrate your amp and take away some discrepancies between your various recordings.
Hans
Could you feed your 60dB phono amp with a 0.42mV sweep signal from REW from 1Khz to at least 20Khz or even higher, this being equal in level to 0dB at 5cm/sec.
This will calibrate your amp and take away some discrepancies between your various recordings.
Hans
Nothing is wrong with signals being louder as 0dB, it doesn’t stop at 0dB.
That’s exact what Karlov & Happ are showing.
Hans
First calibrate your phono amp over a broad spectrum before making conclusions
I will try tomorrow,
So far I used 0.35 mV from soundcard but that's easy to bring to 0.42mV.
Problem is to determine what is 0db@5cm/sec in V as this LP I have is nothing like trustable?
So far I used 0.35 mV from soundcard but that's easy to bring to 0.42mV.
Problem is to determine what is 0db@5cm/sec in V as this LP I have is nothing like trustable?
Dear Hans, I run many consistent tests with phono preamp feed by generated signal, and it always shows the same predictable results, spot on. I will repeat results tomorrow.
Issue is when signal from Ortofon LP is played on my TT, than things get weird.
With normal music LP it is still predicable, even with music one can just see overall level and dynamic....
Issue is when signal from Ortofon LP is played on my TT, than things get weird.
With normal music LP it is still predicable, even with music one can just see overall level and dynamic....
Yeah, sorry, always press send to early.... I have almost the same results with RME built in mic preamp set at high gain as my preamp... It's hard to believe preamp is wrong
For good results you should look at setting 5 cm/sec at 1 kHz at about -18 dB relative to full scale on your A2D. I think that is probably the minimum headroom you want.
Dears, here is sanity check I run just now to make sure something did not go in fog on my desk, sorry if this is too much information.
I run REW captures and controlled RMS voltage with Fluke 87 for calibration.
Sources of signal were:
1. generated from soundcard at 1V RMS and reduced by 2x47kohm(94kohm) / 33 Ohm to 0.35mV RMS. Sweep from 10 to 50,000Hz and 1kHz tone
2. from Ortofon test record played on my TT with BenzM Ruby II naked, tracks 1 to 4 for sweeps, and track 5 for 1kHz test tone
Amplifiers are both linear:
A. My own 2x SSM2017 each with 60db gain, totaling in 66db fully differential
B. RME soundcard mic preamp set at 65db gain
These are 4 sweeps, legend of which is in bottom, fluke measurements were about double the value shown on Y axis:
Light blue is generated sweep amplified by RME mic amp set @65db.
Red is same generated signal through my preamp, showing that or RME preamp is more than 65db, or my preamp is 60 and not 66db.
Now confusing, From LP :
Green is sweep peak from my preamp
Blue is same through RME preramp, this time RME mic preamp has slightly less gain, opposite than with generated signals.....???
Now 1kHz, same inputs, same outputs:
Generated signal feed to my 66db preamp. Fluke measurement of the input is almost exactly the same as indicated on Y: 688mV
Same input, but this time through RME mic preamp @ 65db . Gain is apparently higher than from my preamp... BUt mine shows bit better noise and THD
Than my preamp from ortofon LP test tone 1kHz
And same LP track via RME mic preamp @65db:
Note, Ortofon LP has 4 left channel 1khz tracks, what I show is the best one, on others I get up to 6% THD and SNR in low 30's
Confusion is that when using generated tone RME mic preamp has more gain, when playing from LP and cartridge, my preamp has more gain.... About this one Im not sure whats going on.
But otherwise, I think numbers are consistent....
I run REW captures and controlled RMS voltage with Fluke 87 for calibration.
Sources of signal were:
1. generated from soundcard at 1V RMS and reduced by 2x47kohm(94kohm) / 33 Ohm to 0.35mV RMS. Sweep from 10 to 50,000Hz and 1kHz tone
2. from Ortofon test record played on my TT with BenzM Ruby II naked, tracks 1 to 4 for sweeps, and track 5 for 1kHz test tone
Amplifiers are both linear:
A. My own 2x SSM2017 each with 60db gain, totaling in 66db fully differential
B. RME soundcard mic preamp set at 65db gain
These are 4 sweeps, legend of which is in bottom, fluke measurements were about double the value shown on Y axis:
Light blue is generated sweep amplified by RME mic amp set @65db.
Red is same generated signal through my preamp, showing that or RME preamp is more than 65db, or my preamp is 60 and not 66db.
Now confusing, From LP :
Green is sweep peak from my preamp
Blue is same through RME preramp, this time RME mic preamp has slightly less gain, opposite than with generated signals.....???
Now 1kHz, same inputs, same outputs:
Generated signal feed to my 66db preamp. Fluke measurement of the input is almost exactly the same as indicated on Y: 688mV
Same input, but this time through RME mic preamp @ 65db . Gain is apparently higher than from my preamp... BUt mine shows bit better noise and THD
Than my preamp from ortofon LP test tone 1kHz
And same LP track via RME mic preamp @65db:
Note, Ortofon LP has 4 left channel 1khz tracks, what I show is the best one, on others I get up to 6% THD and SNR in low 30's
Confusion is that when using generated tone RME mic preamp has more gain, when playing from LP and cartridge, my preamp has more gain.... About this one Im not sure whats going on.
But otherwise, I think numbers are consistent....
Drbulj, good plots and very useful.
To refresh my memory, what impedance does the Cart see when connected to your SSM2017 and what impedance does it see when connected to the RME Mic input.
And what is the Cart’s impedance of the channel you use.
Slowly the numbers are starting to converge nicely.
Hans
P.s. one last question: what about the overhang of your Cart position.
When not right, you will get similar results in FR and also distortion of just one side of the sine wave, exactly what you are facing.
To refresh my memory, what impedance does the Cart see when connected to your SSM2017 and what impedance does it see when connected to the RME Mic input.
And what is the Cart’s impedance of the channel you use.
Slowly the numbers are starting to converge nicely.
Hans
P.s. one last question: what about the overhang of your Cart position.
When not right, you will get similar results in FR and also distortion of just one side of the sine wave, exactly what you are facing.
What exactly do you mean ?
I see 2 left and 2 right channels, or do you also include side 2 ?
Hans
Attachments
Dear Hans,
Thanks, not home right now but I can answer some:
Rin my preamp =1kohm
Rin RME mic preamp =2 kohm
Ruby impedance is 40ohm, one Chanel has slightly less, will see which I used whan back
Yes, I mean 2 left 1khz channels on one and 2 on other side. I used track 5 side 2
Thanks, not home right now but I can answer some:
Rin my preamp =1kohm
Rin RME mic preamp =2 kohm
Ruby impedance is 40ohm, one Chanel has slightly less, will see which I used whan back
Yes, I mean 2 left 1khz channels on one and 2 on other side. I used track 5 side 2
Is #399 the setup you used, while measuring between points A&B ?
Could it be that the Riaa network behind A&B gives too much load on the SSM2017's, thereby affecting their FR ?
Hans
Could it be that the Riaa network behind A&B gives too much load on the SSM2017's, thereby affecting their FR ?
Hans
There is definitely something very wrong in your test setup.
1) Playing the 1Khz tone from the LP with 66dB gain gives 723mV, meaning that your Cart produces 0.36mV at 5cm/sec@1Khz (image 4), seems o.k.
2) Measuring through the Mic input shows 547mV, meaning that with 0.36mV from the LP, gain from the Mic input is 63.3dB (Image 5)
3) Now generating a 0.351mV 1Khz tone from your soundcard through the 66dB SSM should give 702mV out, but it is 669mv in image 2, so effectively the input seems to be not 1Veff but 0.95V.
4) So, using this same 0.95Volt via the same divider into the 63.3dB gain Mic input should give 488mV, but your image 3 shows 1.818Volt or 3.7 times as much and also the noise has gone up with the same amount.
As long as you don't get these figures in harmony, no measurement can be trusted.
But first of all, check your Cart's overhang.
Hans
1) Playing the 1Khz tone from the LP with 66dB gain gives 723mV, meaning that your Cart produces 0.36mV at 5cm/sec@1Khz (image 4), seems o.k.
2) Measuring through the Mic input shows 547mV, meaning that with 0.36mV from the LP, gain from the Mic input is 63.3dB (Image 5)
3) Now generating a 0.351mV 1Khz tone from your soundcard through the 66dB SSM should give 702mV out, but it is 669mv in image 2, so effectively the input seems to be not 1Veff but 0.95V.
4) So, using this same 0.95Volt via the same divider into the 63.3dB gain Mic input should give 488mV, but your image 3 shows 1.818Volt or 3.7 times as much and also the noise has gone up with the same amount.
As long as you don't get these figures in harmony, no measurement can be trusted.
But first of all, check your Cart's overhang.
Hans
Correct, that is the setup. I think from there you can see that each amp input sees full cart V, not half. So gain should be 66db
R1's of RIAA are 7k15 each, that should not pose problem for SSM2017 output...
This all works
Now this was I was swetting about, where did another 10db of gain came from and all noise in RME mic amp.... Checked all settings 3 times, shanged between mic amps... all the same. Finally I restarted computer and RME , and whoalla!
Line input on RME via my preamp - Preamp in measured by instrument 998mV, preamp output 688mV
Through RME mic preamp @65db, input same, output cant measure by instrument as is inside RME:
HAve no idea what it was..... but restarting made it logical again...