Five-band equalizer for transceiver. Five-band graphic equalizer on the LA3600 chip. An example of making inscriptions
It is aimed more at radio amateurs who want to hold a soldering iron in their hand. If this is a homemade transceiver, the device board is installed inside, configured once and hidden. Also suitable for owners of imported transceivers who want to make it in a beautiful case, remove all the knobs for adjustment, and generally choose a design to suit their taste (or hide it inside the transceiver, if space allows).
Similar to the first one with the only difference that the board is not installed inside the transceiver, but is intended for installation by the user in the case.
It is more aimed at radio amateurs who have already played enough with a soldering iron and just want to enjoy life. I took the box, connected it with one “cord” to my beloved friend and twisted my hands without thinking about which wire to solder where. In this case, I will have to think, because there are a large number of transceivers and the pinout of the microphone connector is far from the same. But the decision has been made, it’s too late to retreat. The only caveat is that the product in the case will appear a little later than the finished board (what came first, the egg or the chicken?), it takes more time to develop the circuit and test it with different “Bourgeois TRX”. I want to emphasize that the device will have one cord (and of course a PTT connector), there won’t even be any extra wires for the power supply (and all this will still work))). Which option to choose is up to you.
All information about the device “in a housing with external adjustment knobs” will be posted on the page there ⇒
The device is in the form of a ready-made, configured board shown in the figure below.
The board is double-sided and measures 40x50mm (height 15mm). All adjustment elements (tuning resistors) are located on one side of the board. Power supply from +8 to +15V. Current consumption is about 15mA. An eye estimate says that you can use a “crown” battery as a power source and it will last for 30 hours during continuous operation (but who will use this “crown” if any transceiver has a 12-14V source). There is a stabilizer at the power input, its secondary role is to stabilize the voltage, and the main role is filtering (by the way, not everyone knows this, no RC filter will provide such filtering as a stabilizer)! The device diagram is presented below:
Recommendations for setting up the device. Set the microphone gain level to minimum (R10 all the way clockwise), the equalizer and compressor resistors in the middle position. Gradually adding amplification to the microphone with resistor R10, we control the lighting of LED VD1 (while keeping the microphone in the working position). You need to configure it so that the LED does not light up all the time, but lights up at louder sounds. When the LED lights up, this indicates that the compressor threshold has been exceeded, in other words, the signal begins to compress.
How to set the equalizer is a purely personal matter and recommending anything here is a thankless task. So I’ll just write how I did it. The goal was the following - to bring the frequency response of your signal as close as possible to the frequency response pink noise (- 3 dB per octave, for example, if you have a level of “0 dB” at a frequency of 300 Hz, then at a frequency of 600 Hz the level will be “-3 dB”, see the figures below). Trimmer resistors were set as follows:
R12-"80-100%"; R13-"0-20%" ; R14-"0%"; R15 -"0%"; R16-"100%" (0% means all the way clockwise, that is, the minimum). This was optimal for my voice, transceiver and PTT. Most likely you will get completely different values, twist it, adjust it, don’t be afraid to experiment. If your signal produces a lot of low frequencies, it is recommended to install a 0.47 µF capacitor at the output of the device (if there is still a lot - 0.22 µF, etc.). If, on the contrary, the low end is not enough, you need to look at your main board, most likely there is a capacitor installed there with a small capacitance - increase it. There will also be little/many lows if the mixer reference oscillator is not configured correctly.
Necessarily! After adjusting the equalizer, adjust the compression and gain levels of the microphone again, according to the method indicated at the beginning of the recommendations!
Below is a picture with a positional image of the elements and overall dimensions of the board:
Below is the pinout for different transceivers
Below is a recording of my signal on a homemade budget TRX (STEP transceiver with one conversion and 8.8 MHz IF). At the beginning of the file there is a standard signal without processing, which I worked with for about 2 years on this device, a PTT switch is used. Closer to the middle of the file, there is a recording from the same transceiver, with the same push-to-talk switch, but using the “Compressor + Equalizer” board, and at the end of the file, a recording from the same transceiver, but instead of a push-to-talk switch, an electret microphone is used. It is recommended to listen to good acoustics in order to fully appreciate the advantages (or disadvantages)). One of the main advantages is not visible on the recording - without a compressor, with loud sounds, the mixer is overloaded - as a result, the transceiver band widens greatly, with a compressor this almost does not happen (depending on the degree of compression and the signal level at the microphone input).
Below are the figures of 3 frequency response signals, the recording of which is given above (The frequency response of pink noise is superimposed on each signal.
Signal without processing with PTT (first signal on record 0-1.18s)
Signal with PTT processing (second signal on recording 1.18-2.22s)
Signal processed with an electret microphone (third signal in the recording 2.22-5.22s)
Let's compare the graphs.Bluethe frequency response of pink noise is shown (let me remind you that I tried to adjust the equalizer so that the frequency response of my signal would repeat the frequency response of pink noise).Violet colorThe frequency response of my signal is shown. The first graph shows that below the frequency of 300Hz, a rollover begins and at a frequency of 100Hz it reaches about -20dB. Naturally, the lower frequencies will not be heard in this situation. Approximately A number of imported transceivers with a 2.4-2.7 kHz filter with a standard PTT switch have a similar frequency response (that is, starting from 300-250 Hz there is a shift towards lower frequencies). In my case, such a blockage was caused by a small transition capacitance from the microf output. amplifier to mixer, about 0.22 µF. If I increased this capacity, the increase in frequencies at 100Hz was not significant, but frequencies in the region of 200-300Hz increased significantly and the signal simply began to drone. By using an equalizer, it became possible to raise frequencies of 100Hz, while dropping 200-300Hz, the result is shown in the 2nd and 3rd graphs. The closest frequency response of the signal to the frequency response of pink noise was obtained in the 3rd graph; it also shows a slight increase in frequencies of 2-2.5 kHz, which will add brightness to the signal.
A recording of the ICOM-746 signal will be added later
Microphone amplifier compressor equalizer reverb in case v.4 (EQ_V.4)
This device was created taking into account all the wishes of the owners (and non-owners) of previous versions and their own ideas.
The photo shows design options for various transceivers and for special customer requirements (such as duplicating a headphone line, or installing additional connectors for personal needs).
EQ_V.4 has on board a low-noise microphone amplifier, a signal compressor, an 8-band equalizer and an echo processor. The device is connected as before - with one cable. Supply voltageIt is taken from the microphone connector of the transceiver, so there will be no additional “snot” hanging around the table. To connect the device to the transceiver, you just need to disconnect the PTT switch from the transceiver and plug it into the gap.This only applies to transceivers f. Icom. If you have a transceiver from another company (Yaesu, Kenwood, etc.), you must connect an external 9-16V power supply to the device. It can be taken either from a separate power source or from the power supply to which your transceiver is connected. The following figure shows the connector for connecting external power:
The microphone amplifier has a noise level comparable to the noise level of the well-known low-noise chip NE5532, and its adjustment range is about 20dB. This allows you to connect both electret and dynamic microphones.
The so-called “compressor”, if we consider it from the technical side, does not have any unique characteristics, I’ll reveal the secret - a regular ALC (and in our circuit it’s double), but practice has shown that it works very well and in most cases, users turned off the standard one compressor of your transceivers (you can’t fool your ears)). The quality of the signal from a cranked compressor can be heard on more than one recording, and, rest assured, it raises the peak factor quite well.
8-band equalizer, what can I add here, a good graphic equalizer with 8 adjustments in a frequency band of almost 3 kHz. The frequencies were not chosen by chance; the meaning is quite deep and I think it’s worth abandoning long explanations. Those who understand at least a little about music, have an ear, know what an overtone and formant are and will understand, and those who don’t know, just believe me - this is how it should be)).
And of course, what bothers everyone, but what you want to have is an echo in the signal. I won’t be too lazy to repeat myself - know when to stop!! An excess of echo gives your interlocutor a reason to do anything))
In order to completely remove the presence of Echo in the signal, you just need to turn the “Echo” knob to minimum and that’s it. Therefore, additional bypass switches/relays were avoided.
5
- band microphone - equalizer for transceiver
Model<< ME 008>>
Ukraine, Kharkov
PURPOSE
The proposed equalizer is a device that allows you to set the required amplitude-frequency response of a signal transmission channel (English: equalize, equalizer, compensator). It allows you to equip amateur radio stations with a complete device that includes a high-quality electret microphone combined with a 5-band equalizer. Using a microphone<< ME 008 >> allows you to obtain the necessary frequency response of the microphone path, which can dramatically increase the readability of the signal. This device is intended for radio amateurs who do not have an equalizer built into the transceiver, or as a separate unit.
DESIGN
and technical specifications
Design.
The device is made in the form of a separate block of impact-resistant polystyrene, the entire internal surface of which is metallized for shielding from external electromagnetic fields.
On the front and rear panels there are all the necessary informative inscriptions in Latin script. The use of modern technologies has made it possible to obtain high resistance to external influences, abrasion, etc.
For shielding from external electromagnetic fields, the microphone holder is made of a flexible metal hose about 25 cm long. The polished chrome coating makes it highly resistant to external influences, abrasion, etc. and excellent aesthetic performance.
The weight of the device is about 250 g.
Dimensions - 90 x 46 x 150 mm.
Regulatory and control bodies.
Regulators.
The frequency response regulators are made in the form of 5 axis regulators, which are located on the front panel of the device. The position of the knobs displays the frequency response of the device. A flat signal characteristic corresponds to the position of the knobs at 12 o'clock. Zavalu frequency response - 10 dB. and at the 8 o'clock position. Raising the frequency response at the "16 o'clock" position In equalizers of this type, using a regulator installed on the rear wall of the device, you can adjust not only the magnitude of the rise in the frequency response, but also the level of the output signal within significant limits. Other parameters are determined by the circuitry and cannot be changed.
Controls.
The device also contains a push-button switch<< PTT >> push-type (without locking) designed to switch the transceiver to the "TRANSMITTING" mode by pressing it with the index finger. Switch<< PTT >> installed on the top panel (red button). To the right of the button<< PTT >>a push-type button (without locking) is installed, designed to adjust the operating frequency of the transceiver up the frequency and on the left side of the button<< PTT >> a push-type button (without locking) is installed, designed to adjust the operating frequency of the transceiver downward in frequency.
Detachable connectors.
On the rear panel of the device there is an 8-pin plug connector designed for:
1) generated signal output<< OUT >>
2) switching circuits<< RTX - PTT >>
3) control (tuning) of the transceiver by frequency
There is also a 3.5 mm jack on the rear panel for connecting a standard microphone head or a headset with a microphone.
There is also a special connector for supplying +13.8 V supply voltage on the rear panel.
The device is connected to the transceiver using a special 0.75 meter long cable included in the delivery kit, on one side
equipped with a corresponding connector for connecting to the device, and on the other side with a special 8-pin connector (supplied upon separate order).
Specifications.
Frequency response adjustment limits are no less than 10 dB. + 12 dB.
Harmonic coefficient no more than 0007%
Noise with a frequency band of 50 Hz - 5 KHz. no more than 3 mkv.
Protected from external electronics. magnetic fields - complete shielding by metallization of the inner surface of the product body and microphone holder.
Protection against the penetration of external noise through the connecting cable - the use of a P-shaped filter along the power circuit, a P-shaped filter along the microphone input circuit
Supply voltage - from external transceiver power supply 13.8 Volts
Current consumption - 15 mA max.
Note.
Characteristics measured with a "flat" frequency response with bandpass filter controls in the middle position at "12 o'clock"
Contents of delivery.
1) 5-way microphone - low-frequency equalizer for transceiver
2) Connecting cable + special 8-pin connector - 1 pc.
3) A piece of wire (red) equipped with a special connector for supplying 13.8 V voltage from the transceiver power supply
4) Wind-noise-proof foam screen
5) Packing box
<< KENWOOD >> << ICOM >> << YAESU >> and etc..
The special 8-pin connector, the cable part (female) connected to the product, is equipped with a red mark.
R connection cable solder
ME 008
1 pin – (+ MIC)
2 pin – (+ PTT)
Pin 3 – (F. DOWN)
4 pin – (F. UP)
5 contact – (NC not used)
Pin 6 – (N C not used)
Pin 7 – (-MIC)
8 pin – (supply - voltage 13.8 Volts from the microphone connector of the transceiver to the product)
Supply voltage is supplied
from the transceiver power supply with a red (+ only) wire equipped with a special connector included in the product delivery set
Or from another connector located on the rear panel of the transceiver, which has a transceiver on-board voltage of 13.8 volts.
Attention!!!
Connect the connecting cable to the microphone with the power supply voltage turned off.
The microphone cable must be wired from the transceiver side by a suitably qualified specialist.
The manufacturer reserves the right to make changes to the device layout and external design.
All changes are aimed at improving the electrical parameters and ergonomics of the product.
Please send your feedback and suggestions by email:
radiobomba@mail.
Ukraine, Kharkov
2008
4 BAND LF EQUALIZER
The most common and most widely used processing of audio signals is the processing associated with changing their timbre. Today you can often find radio amateurs who have an equalizer built into the transceiver or located outside it - a device capable of equalizing the amplitude-frequency characteristic of the signal transmission channel (eng. equalize - equalize equalizer - equalizer, compensator).
We are not talking about equalizing the frequency response in the literal sense of the word and the identity of the signal amplitude across the entire frequency spectrum of the microphone amplifier, since this is not necessary. Creating the necessary frequency response of the microphone path, capable of dramatically increasing the readability of the signal - that is the task.
An equalizer is a frequency response control that allows you to both correct poor-quality sound and create a completely new frequency response as needed.
The simplest example of an equalizer is the usual passive tone controls for high, low, and sometimes mid frequencies. Tone controls are an extremely primitive type of equalizer, since they consist of only two or three controllable filters. Due to the simplicity of the design, the filters included in the tone controls are usually connected to each other in series
Modern element base allows the use of more advanced devices assembled on active elements. We are talking about active bandpass filters based on op-amps. It should be noted that the more filters, the more the frequency response can be changed. Typically, 8-10 of them are used.
All types of equalizers can be manufactured according to two very different design principles - serial or parallel circuits. In a serial circuit, the signal
passes through all elements and nodes of the circuit, regardless of whether this part of the signal spectrum changes in this cascade or not. In a parallel circuit, the input signal is divided by a set of filters connected in parallel into a number of frequency bands, the output signals of which are then added to or subtracted from the input signal.
Parallel connection of filters in the tone control, as opposed to sequential ones, allows you to reduce the phase distortion introduced by the equalizer into the signal. This is especially important with 10 or 32 bands of graphic equalizer, where only parallel connection of filters is acceptable.
There are two fundamentally different types of equalizer - graphic and parametric.
A graphic equalizer is, in essence, one of the types of tone blocks designed to control tone at several fixed frequencies. Its controls are made in the form of slide controls, due to which the position of their knobs seems to display the frequency response of the device in graphical form, which is where the name itself comes from. In equalizers of this type, you can only adjust the amount of rise and fall of the frequency response; the remaining parameters are determined by the circuitry and cannot be changed.
The parametric equalizer has the greatest flexibility in its adjustments. It allows you to control not only the filter gain, but also its average frequency, as well as the quality factor (adjustable bandwidth). The parametric equalizer, therefore, has three controls for each control band - according to the number of parameters to be set.Thus, if an equalizer has three control knobs for each control band, then it is a parametric equalizer.
Like graphic equalizers, parametric equalizers can also be implemented in parallel or serial circuits. The ranges of parameter changes in a parametric equalizer reach significant values.
A semi-parametric equalizer is sometimes used in mixing consoles. It allows you to control the filter gain and its average frequency. It differs from the parametric one in that it does not have the ability to change the quality factor of the equalizer, the bandwidth of the frequencies it captures.
A paragraphic equalizer is a hybrid of parametric and graphic equalizers. Actually, this is a multi-band parametric one, but it has the design of the frequency response rise/fall regulators like a graphic one, with potentiometers in the form of sliders. Thanks to its enormous capabilities, a paragraph equalizer allows you to obtain almost any type of frequency response. Due to its complexity and high cost, this type of equalizer is not widely used, but is produced by some manufacturers.
Microphone - MD380A. VR 1 "Microphone" - 80% (up to a level of 250 mV at the input DA 2), VR 2 "Gain" - 90%, VR 3 "High" -100%, VR 4 "Mid 2" - 100%, VR 5 "Mid 1" - 50%, VR 6 "Low" -100% ,VR 7 "Output" (in the "Output 620 Ohm" position) - 80% (the percentage given is the position of the potentiometer slide when rotating clockwise).
A bipolar stabilized unit is required to power the equalizersupply voltage 15 V and current up to 100 mA.
I would like to add that an equalizer is not a panacea, but a means of signal correction. It can remove unnecessary things, but with its help it is extremely difficult to add something that was not in the path, so everything is important: the operator’s voice, the frequency spectrum of the microphone used, and the presence of the equalizer itself.
An equally important issue is the correct setting of the reference oscillator frequency in SSB -former and the bandwidth of the filter used in it. The wider the transmission filter bandwidth, the easier it is to obtain a studio signal.
I want to thank Alexander, EW 1 RA, who once gave me the Sonor M-08-3 mixing console, which contributed to a more detailed study of this topic.
The results are as follows - the mixing console, after its global study and reconstruction of the circuit diagram, was disassembled into subblocks, the eight 4-band speech equalizers that were in it were transferred free of charge to other radio amateurs. A modernized 4-voice equalizer with fairly high performance has been created.
Circle of Audio Lovers expanding Thank you F 4 ECJ, Erie, G 4 VPC, Egpeu, G 4 EKL, Tony, EW 1 DM, Serge, RW 3 PS, Serge and especially EW 1 RU, Yuri for constructive discussions on topics related to audio processing
I developed a printed circuit board measuring 170x50 mm (Fig. 4, view from the installation side of parts and Fig. 5, from the track side) EW 2 CE Alexander Railchenko
I. Podgorny, EW1MM, MINSK.
Many radio amateurs, regardless of what transceiver they have, try in one way or another to improve the quality of the transmitted signal. Someone whose voice timbre is “wrong”, someone who has an unsuitable microphone. In home-made devices, correction is usually achieved by selecting the values of C and R in the corresponding circuits of microphone amplifiers, or the frequency response is corrected using simple tone controls; owners of “branded” ones often buy expensive studio microphones and equalizers, the use of which in R/L equipment is more unjustified than necessary .
Be that as it may, the use of an equalizer very often allows you to improve the signal, and you can do it almost for free if you find a couple of hours and make the proposed device yourself. The signal quality will not be worse than when using a “proprietary” equalizer
In the journal Funkamateur N 8 for 2004 p. 801 Marcel Schneider published an article where he described a simple five-channel low-frequency equalizer on a chip TA7796P, intended for use on amateur radio stations, (Fig. 1). If you come across a chip for stereo devices, don't worry. In the second half, you can assemble an equalizer for the receiving path, which will at least partially compensate for the lack of chipboard (or any other filter).
The author took the diagram from the manufacturer Toshiba as a basis. TA7796P(Fig. 2), which was developed for use in household appliances, adding an amplifier on V1 to use an equalizer in the microphone amplifier path and an emitter follower on V2, used in musical equipment.
Variable resistors RP1-RP5 with linear characteristic. Resistors of 50 kOhm can be used, in this case, instead of the jumper R*, a resistor with a nominal value of 3.3 kOhm is soldered in, or other R* will have to be changed accordingly.
Fig.2
In my opinion, the capacitance of the 10 µF coupling capacitors is unreasonably high, which only leads to signal clogging with low-frequency noise, for example. from a fan or transformer, and therefore a capacitance of 0.047-0.1µF in the VT1 base is quite sufficient, just as a capacitance of 0.5µF in the VT1 collector is sufficient; 1µF at VT2 emitter; in the VT1 OOS circuit, the capacitance in the emitter can also be reduced to 0.47-1µF.
The polarity of the switching capacitor at the output should be clarified when using an equalizer with a specific transceiver, or even better, use a non-polar capacitor.
To match the level with the transceiver, it is better to install a trimmer or variable resistor at the equalizer output instead of a constant resistor in the VT2 emitter circuit.
Some data TA7796P:
Five-channel low-frequency mono equalizer E pit = 4-16V. I supply = 6 mA. Uin, Uout= 0.775V (0db) Uneven frequency response 20Hz-20kHz=1.5db. Unoise = 3µV. K g = 0.007% at U out = 245 mV.
Correction depth ± 11.5db. Analogues: DBL1046; KA2223; M5226P ; LA3600; TA7796P
P.S. The device starts working immediately and without any changes suggested by me.
Good luck with your repetition! 73!
Nikolay Polyukhov, Stuttgart
DF3NPex:UL7LCW; UL7LC; UN7LC; UN0L
