Modifying PYLE PP444 Preamp
The pre-amplifier PYLE pp444, is a device of excellent performance. However it was designed to be applied to turn-tables of acetate discs. Therefore its electronic design involves a pre-amplification equalization known as RIAA.
Without going into detail we will say that this curve accentuates low frequencies and attenuates high frequencies.
The reason is explained by the fact that the acetate discs produced in the last half of the last century were recorded for technical reasons, which we will not detail, with an emphasis on high frequencies and attenuation at low frequencies.
Below is a graph showing the RIAA RECORDING curve (1)
Without going into detail we will say that this curve accentuates low frequencies and attenuates high frequencies.
The reason is explained by the fact that the acetate discs produced in the last half of the last century were recorded for technical reasons, which we will not detail, with an emphasis on high frequencies and attenuation at low frequencies.
Below is a graph showing the RIAA RECORDING curve (1)
To properly reproduce this recording, it is necessary to reverse the equalization process. In other words, create a reproduction curve with an inverted equalization. As in the following chart.
RIAA REPRODUCTION curve. (1)
RIAA REPRODUCTION curve. (1)
As can be seen, the RIAA reproduction curve creates an emphasis on low frequencies and attenuates high frequencies.
THE SOUND SPECTRUM OF A WATCH.
Of course not all the clocks have the same sound spectrum. In principle we can say that conventional wristwatches have an audible spectrum with a distribution between 2kHz and 18kHz. We note that this range may vary and some clocks produce sounds that go far beyond this range (2)
Here are some screenshots that can be informative. These images are in fact analysis of the sound spectrum of real clocks. 3)
Watch Unitas 6431. 16.5 ligne (A little more 37 mm diameter).
THE SOUND SPECTRUM OF A WATCH.
Of course not all the clocks have the same sound spectrum. In principle we can say that conventional wristwatches have an audible spectrum with a distribution between 2kHz and 18kHz. We note that this range may vary and some clocks produce sounds that go far beyond this range (2)
Here are some screenshots that can be informative. These images are in fact analysis of the sound spectrum of real clocks. 3)
Watch Unitas 6431. 16.5 ligne (A little more 37 mm diameter).
And in the following screenshot The specter of a Royce women's watch FHF 69-21. It may be noted that despite being two clocks of different size, the sound spectrum is very similar. Although the presentation of the graph is different, comparisons can be made.
After dedicating a few hours to the PYLE PRE-AMP circuit, we found that by removing the ceramic capacitors from the following values 332P and 821P the curve improved. They are two capacitors per channel. I remove only two to leave one channel with the RIAA curve and the other flat. I must admit that the procedure was very empirical, because I do not have the PYLE PREAMP diagram (I already asked the company).
Here is the picture of the circuit of PYLE PREAMP.
Here is the picture of the circuit of PYLE PREAMP.
You can download the audio file in mp3 format from the tic-tac of an Omega stopwatch.
fyle-noriaa-9160a-1225-212532.mp3 | |
File Size: | 636 kb |
File Type: | mp3 |
Using the Pre-amp in watch analysis software
Once the indicated ajusts have been made, obtaining a good quality signal from the preamplifier of any watch is simple. You need an electric piezo sensor. I built one from a piezo electric twiter. But you can buy a Clip-On Pickup for Acoustic Guitar. Some adjustments should be made to the secure device, but they will be of little consequence.
This is the result with "tg" Software.
The tg program has an important feature, lengthen the wave to analyze in detail each section of it. There are 3 horizontal windows on the right. The superiors present each of the sounds of the clock in one the tic and in the other the tac. In the below one the two events one behind the other are highlighted in blue, where a comparison of the waveform can be made. The numerical values in the upper part show in the next order the deviation of the gear which in this case is a delay of 21 seconds. A beat error of 0.5 milli seconds. And then an amplitude of 204 degrees. The value 18000 is the beat of the clock, 18000 alternations per hour.
Using the Pre-amplifier with Watch-O-Scope
UPDATE 10 MARCH 2021
I post an update and improvement on modifying the Pyle 444 preamp.
It was made by removing a capacitor seen in the photograph.
In addition to what has already been done, the 4.7uF electrolytic capacitor was removed. And it was replaced by a 473 or 0.047 uF. 47nF. In red.
The result of removing the annoying low frequencies is seen in the last image.
It was made by removing a capacitor seen in the photograph.
In addition to what has already been done, the 4.7uF electrolytic capacitor was removed. And it was replaced by a 473 or 0.047 uF. 47nF. In red.
The result of removing the annoying low frequencies is seen in the last image.
13 Seconds record with Pyle modified and piezo disk.
pyle_mod_piezo_disk.wav | |
File Size: | 1217 kb |
File Type: | wav |
This is the only adjustment that needs to be made to the PYLE PP444 PRE-AMPLIFIER, to be used as a preamplifier for the sound of a clock. I paid about 25 USD. And I am very satisfied with their performance.
I have a couple of projects that I want to show here using this preamp. The first is the status detector of an electronic quartz analog clock. This will allow us without opening the clock to know if the battery is good or if some mechanical problem has blocked the movement. The second is a magnetism detector. Ideal for watchmaking as it can detect if the tool or any movement of the watch is magnetized.
You can also view related information at: reparacionderelojes.weebly.com/watch-o-scope-mic.html
References:
1) Cut and Thrust: RIAA LP Equalization.
2) Signature Analysis of Mechanical Watch Movements by Reassigned Spectrogram
3) Vídeo de analisis de espectro visible de un reloj
4) For "tg" Software: ciovil.li/tg.zip
5) For Watch-O-Scope Software: www.watchoscope.com/download.html
I have a couple of projects that I want to show here using this preamp. The first is the status detector of an electronic quartz analog clock. This will allow us without opening the clock to know if the battery is good or if some mechanical problem has blocked the movement. The second is a magnetism detector. Ideal for watchmaking as it can detect if the tool or any movement of the watch is magnetized.
You can also view related information at: reparacionderelojes.weebly.com/watch-o-scope-mic.html
References:
1) Cut and Thrust: RIAA LP Equalization.
2) Signature Analysis of Mechanical Watch Movements by Reassigned Spectrogram
3) Vídeo de analisis de espectro visible de un reloj
4) For "tg" Software: ciovil.li/tg.zip
5) For Watch-O-Scope Software: www.watchoscope.com/download.html