Fast Improved Buffer
I implemented the Standart Buffer and it sounds just fine. But me being me i have of cause an idea for an even better version. I call it IBuf for Improved Buffer. I will also make a headphone amp with it. Frequency response is up to 40MHz stable with very low distortion and noise.
I implemented the Standart Buffer and it sounds just fine. But me being me i have of cause an idea for an even better version. I call it IBuf for Improved Buffer. I will also make a headphone amp with it. Frequency response is up to 40MHz stable with very low distortion and noise.
In the first plot yellow is a 1kHz tone with +12dB, red is the ULN phonostage with input shorted. What is interesting is that i get a dynamic range now of 76dB over 100Hz, stone in plastic groove. I had cleaned the stylus really well but it could also come from less noise in the phono. This phono is some 3dB better then the measurements of the stage i posted on the "OPamp for RIAA" thread.
Next plot is the input shorted ( red ) compared to the result with cartridge connected. You can see here some hum comming from the turntabe and what is really strange is that the noise is some 1/2 dB better WITH the cartridge connected at higher frequencies? I have no expanation for that phenomenon at the moment. Maybe it is just the resolution of my measurement setup.
The last plot is the phonostgae shorted with motor off and motor on. You see a lot of humm comming in because the phonostgae sits only a few centimeters away from the motor and is not shielded in a cabinet but on a double sided circuit board. This effect is much reduced when the cartridge is connected. See the second plot.
Next plot is the input shorted ( red ) compared to the result with cartridge connected. You can see here some hum comming from the turntabe and what is really strange is that the noise is some 1/2 dB better WITH the cartridge connected at higher frequencies? I have no expanation for that phenomenon at the moment. Maybe it is just the resolution of my measurement setup.
The last plot is the phonostgae shorted with motor off and motor on. You see a lot of humm comming in because the phonostgae sits only a few centimeters away from the motor and is not shielded in a cabinet but on a double sided circuit board. This effect is much reduced when the cartridge is connected. See the second plot.
Yes, it has a speed control. I set speed with a Clearaudio 300Hz strobe and have reported on the other thread that my turtable runs low or that the test record is not cut with the correct speed. I will measure with another test record and when i get the same result i will speed up my turntable a bit.
A major measurement session was not on the agenda today. I wanted to finish the +-17V Hypnotize. I have set the CCS but not the voltage. That must wait until tomorrow. Instead
i decided to dress me in amour and go to battle with the vinyl and out of nowhere comes the DIN45549 test record from 1978, never played, mint condition. What was immediately obvious is that the Phönix was cut a bit slow. Still the turntable did not hit the 1000Hz mark and after at east 20 tryes i nailed it down. 1000Hz exactly and stable over time. I repeated the mesurement several times. Good. So having the DIN record on the table i also performed a 300Hz-3000Hz intermodulation test ( very hard to aquisite )
and used this test also for crosstalk measurement. I then put the HiFi News test record on and measured the FRD of my Titam i ULN combination with pink noise. Everything in order here and as you see i also use my Time Domain subsonic filter now, so no exess in the 6 Hz region any more. Pink noise falls of with 3dB octave to the response is bend toward the treble.
i decided to dress me in amour and go to battle with the vinyl and out of nowhere comes the DIN45549 test record from 1978, never played, mint condition. What was immediately obvious is that the Phönix was cut a bit slow. Still the turntable did not hit the 1000Hz mark and after at east 20 tryes i nailed it down. 1000Hz exactly and stable over time. I repeated the mesurement several times. Good. So having the DIN record on the table i also performed a 300Hz-3000Hz intermodulation test ( very hard to aquisite )
and used this test also for crosstalk measurement. I then put the HiFi News test record on and measured the FRD of my Titam i ULN combination with pink noise. Everything in order here and as you see i also use my Time Domain subsonic filter now, so no exess in the 6 Hz region any more. Pink noise falls of with 3dB octave to the response is bend toward the treble.
Now comes the real surprise. That DIN record is super quiet. I do not know on what phantastic equipment they have manufactured this miraculous gem but SN is better then 80dB over a broad range and improves to 90dB in the upper midrange. i heard that Telefunken had developped super low noise vinyl in the 70th with a secret formular forever lost but i was not prepared for THIS:
There was a CBS STR series of test records that had very clever tests as it seems but I haven't seen any for real. Did you bump on any in the vinyl glory days?
P.S. So the HFNRR was cut OK for speed, agreeing with the Tele? Shall I trust it, bcs in my turntable it will be tweaky by changing belt or ''thickening'' the pulley with nail polish. Also at what frequency you refer your dynamic range talk? 100Hz?
P.S. So the HFNRR was cut OK for speed, agreeing with the Tele? Shall I trust it, bcs in my turntable it will be tweaky by changing belt or ''thickening'' the pulley with nail polish. Also at what frequency you refer your dynamic range talk? 100Hz?
I did not test the HFNRR for speed, only for FRD. I will compare that tomorrow and then tell you. The Phönix was slow though.
It´s hard to say where we put the frequency to define dynamic range. You see in the range under 100Hz it is decreasing fast. 100 Hz is a tough test too but us being tough too could put it there for reference. Not discounting the humm spike there we land again at slightly over 70dB, close to Burkhard Vogel´s calcuation of 72dB but that was with DMM. I will look up Burkhard book. Maybe he already came up with a sugestion about what frequency range we are talking about. I do not like to come up with a new definition each day. That is only confusing.
I had a short listen to Carly Simon and James Taylor with the new set speed and it sounds different if not better. I think i have to adjust my woofer again for level and phase. Because of the Fletcher-Munson curve ( or newer variants) small changes in sub level can be very audible because that curve is very steep in the bass and it can easily happen that we land in the "just audible" range where before was nothing.
It´s hard to say where we put the frequency to define dynamic range. You see in the range under 100Hz it is decreasing fast. 100 Hz is a tough test too but us being tough too could put it there for reference. Not discounting the humm spike there we land again at slightly over 70dB, close to Burkhard Vogel´s calcuation of 72dB but that was with DMM. I will look up Burkhard book. Maybe he already came up with a sugestion about what frequency range we are talking about. I do not like to come up with a new definition each day. That is only confusing.
I had a short listen to Carly Simon and James Taylor with the new set speed and it sounds different if not better. I think i have to adjust my woofer again for level and phase. Because of the Fletcher-Munson curve ( or newer variants) small changes in sub level can be very audible because that curve is very steep in the bass and it can easily happen that we land in the "just audible" range where before was nothing.