Amplifier Corvette 100U-068S 1993 release. The amplifier is complete, has a layout similar to an amplifier Brig 001. The power amplifier has two separate supply voltages. +-23V and +-42V.
Brief description of the amplifier. Amplifier weight 7 kg. The power transformer is covered with a metal shield, but not completely covered. It is small in power, about the same as in an amplifier Brig 001. The amplifier body is assembled on a metal chassis, which is a sheet of metal approximately 0.4 mm thick. with holes for ventilation. Power amplifier boards, a power supply capacitor block, a power transformer, a pre-amplifier and a tone control unit are secured to this sheet with screws. All modules are secured with screws - similar to self-tapping screws. The top of the amplifier is closed with a lid, which is combined with the front front panel of the amplifier. The front panel of the amplifier is plastic, black. The plastic is rather weak and prone to wear, so over time the volume, tone, and balance knobs may become “worn.” Also on the buttons. It is possible to cover the front panel with varnish or other composition to preserve appearance. KRYLON varnishes can be used to coat plastic.
The slider-type volume control is assembled from resistors, the same as on the Odyssey-010 amplifier. Only in the Odyssey, all regulators are assembled from permanent resistors. In the Corvette, the remaining controls - balance, tone, loudness - are simple variable resistors SP3-33. Over time, they also become unusable, the track wears out or breaks off. Each button is illuminated with a separate light. Miniature CMN light bulbs are used as illumination, shining through a red filter built into the front panel. You get red glowing red dots opposite each button.
Appearance of the amplifier.
View of the amplifier with the cover removed.
Internal layout of the amplifier.
Separately, we should talk about the backlighting of the buttons, since everyone is faced with burnt out light bulbs. The buttons are illuminated by miniature SMN lamps of 10-12 Volts. The voltage on the lamps is approximately 9 Volts. The bulbs cost 5 pieces each in special plastic blocks; thin antenna leads are threaded into the holes and soldered to the output points. In this amplifier, some of the bulbs have already failed. You can replace them with the same ones, you can find them. If you replace light bulbs with LEDs, it will be more preferable and beautiful. In order to replace light bulbs with LEDs, you need to do the following: LEDs need to be taken white. You can also take red LEDs, but since there are already red filters in the front panel, I don’t see the point in installing them. The light filters in the front panel from its inner part are convex, with outside. those. on the front they look like red dots. Therefore, if you install 3mm LEDs, they will not fit. Their leads can be inserted into the holes in the plastic block, but from the outside they will stand out for their entire length. Therefore, when we close the lid with the front panel, it will not close, the 3mm LEDs will interfere due to the convex filters, and the 3mm LEDs themselves are large.
It is necessary that the LEDs are completely inserted, just like the paws, into the round cells, seats and did not protrude even a millimeter. Otherwise, the cover with the front panel will not close. I picked up these 1.8mm LEDs, with a flat top. They fit perfectly in size and do not protrude beyond the cell. At the same time they shine brightly in white. The second question is how to match them in terms of supply voltage. The light bulbs receive a voltage of about 9 volts. To power the LEDs you need 3 Volts. You need to take 300 Ohm resistors with a power of 0.25 W and connect them in series to each LED. You can calculate the resistor resistance using the formula that is available on the Internet. At the same time, the voltage on the LED is limited to 3 Volts, which is what we need. It all looks like this:
Replacing backlight bulbs with LEDs.
300 Ohm resistors need to be installed on the LEDs in two blocks, which each held 5 pieces. light bulbs The 6-light block, which is located next to the recording input switches, will be connected differently. There is no need to install resistors on these LEDs. They already have 3 Volts. If you put resistors on them, the LEDs will not light up at all, because there will be a voltage drop across them. We have made changes to the amplifier circuit and therefore need to take this into account. It looks like this:
LEDs without limiting resistors on the right side of the recording input switches.
Another nuance - when connecting LEDs, you should take into account the polarity, because the voltage is constant.
Illuminated buttons with new LEDs.
P.S. In amplifiers SANSUI Miniature light bulbs are also used for illumination. They can also be replaced with LEDs, but you need to take into account that the voltage on them is variable and you will also need a diode to rectify the alternating voltage.
The Corvette 100U-68S amplifier has differences in electronic components depending on the year of manufacture. Early versions of the amplifier were equipped with 2 pcs power supply filter capacitors of 15000 µF x 63V. The capacitors were the same as in the Odyssey 010 - K50-37 amplifier. Later releases of the amplifier already had other capacitors - 2200 µF x 63V, which were made up of several capacitors, giving a total of 15,000 µF for each arm.
By the way, in the Odyssey - 010 amplifier, later releases also used 2200 μF x 63V capacitors made up of several pieces. And metal volume and tone control knobs on earlier versions Odyssey - 010 had “notches” for ease of adjustment; in later versions they were no longer “notched”, but simply round.
In Corvettes of later releases they went even further and replaced the output transistors in metal cases KT865 with transistors in plastic cases like KT8101. The version I got is from 1993. And the capacitors and transistors in it have already been replaced in the direction of cheaper ones, or in the 90s the collapse of the Union was already underway.
I decided to replace the 2200 μF x 63V capacitors with new ones, since there was no trust in them. The replacement was made with Jamicon capacitors.
We will install such capacitors in each arm with a voltage of +-42V. You get 16,000 microfarads for each arm.
We are replacing electrolytic capacitors in the power filter.
It is also necessary to carry out maintenance on the volume control resistor. To do this, it must be removed and disassembled. Wipe the contact fields from dirt with alcohol, lubricate all rotating parts with new CIATIM-201 lubricant.
There was another problem with this example of the amplifier. One channel disappeared periodically. The reason turned out to be simple, but finding it was not so easy. The contact on the power amplifier board connector was not soldered. After soldering all the contacts of the power amplifier board connector, the sound became normal and did not interrupt.
Also, another feature of the Corvette amplifier that many encounter is clicking sounds after turning off the amplifier. This amplifier had them too. The first thing you need to do is replace the 22 µF capacitor C2 in the protection unit with a new one and solder separate wires to its terminals, which need to be connected to the free contact group of the PKN network switch. Thus, by turning off the amplifier, we discharge capacitor C2, which does not have enough time to discharge. Perhaps this is due to a change in the circuit to replace light bulbs with LEDs.
The sound of the amplifier is decent. Excellent sound, there is dynamics, it does not color the sound like some amplifiers. There is enough power to spare. The built-in LED power indicator allows you to focus on the power, although it is limited to one channel. Therefore, in order to maintain decent sounding of the amplifier, you need to replace the power filter capacitors. The remaining capacitors can be changed as needed. Some of them are non-polar, some are electrolytic.
The disadvantage of the amplifier is its heating. It is already starting to heat up when working on the headphones. This is the mode of the output transistors, which have a separate power supply of +-42 Volts. At long work at high volume, it will get very hot, so you can install a fan to blow the heatsinks of the output transistors; by the way, the heatsinks in it are small.
When developing the Corvette amplifier, the experience of creating the Brig-001 amplifier was taken into account. It will be of interest to fans of Brig.
Acoustic system Corvette 150AC-001.
Acoustics Corvette 150AC-001- I will describe the features of this acoustics. I'll compare it with 35AC-018 Amphiton.
The acoustics are made of chipboard panels and are made quite neatly. All chipboard panels fit perfectly evenly. The acoustics are painted black, most likely my copies have original black paint. I’ll immediately note the thickness of the walls of the Corvette acoustics. The front wall is made of plywood 25mm thick. In Amfiton 35AS-018, the thickness of the front wall made of chipboard is 38mm, but this is understandable, Amphiton 018th is the leader in front wall thickness among Soviet acoustics of the 35AC series. The woofer in this acoustic system is quite large in size - 300mm. This is 100GDN-3. There are two spacers inside the housing - one between the tweeter, the other located vertically along the rear wall of the acoustic housing. Spacers compensate for the rigidity of the body and the lack of thickness of the front wall.
Everything inside also fits well, there are not the slightest gaps. The rather large 100GDN-3 woofer takes up almost half the volume of the cabinet. Here, of course, a larger body would be needed. The 30GDS midrange speaker is installed on top of the 10GDV-4 tweeter, which is also unusual. The midrange speaker is insulated inside with a cardboard cylinder, which rests against the rear wall of the housing, while creating additional rigidity of the housing.
Wiring in acoustics. What can be noted about it? Made with dignity, the wiring is woven with black thread and neatly laid out. What can you say about acoustic wiring? Amphiton 35AS-018. It uses single-core wire, which is of poor quality and thin. Which definitely needs to be changed. There is no need to change the wiring in Corvettes. It is stranded and thick.
At the bottom inside the case there is a filter on a separate board and a protection board. The protection is connected through a separate connector on the rear wall of the speaker system. The screw clamps are good, but they loosen over time. You need to glue a textolite strip inside the case epoxy resin, tighten the screws and then the screw clamps will work normally.
In my copy, the 100GDN-3 woofer turned out to have a homemade suspension. The pendant was made from rubber seal for windows. Of course, such a suspension will not work normally and it must be replaced with a factory one.
Also, the 10GDV-4 tweeter did not work. There was a break inside the coil.
The sound-absorbing material inside the case is a wad of cotton wool glued in the middle to the rear wall of the case. It is unknown whether the developers proceeded from the volume of sound-absorbing material, but the volume of wool in the two buildings is different. The cotton wool, located in a single lump in the middle of the body, touches the wiring, part of it blocks the hole in the bass reflex pipe, and cotton wool remains are scattered everywhere inside the body. To carefully lay the cotton wool, you can secure it with a piece of gauze. Attach the gauze with a stapler.
Design Features
The speaker body is made in the form of a rectangular non-demountable box made of chipboard, veneered with valuable wood veneer. The thickness of the case walls is 16 mm, the front panel is three-layer (plywood - chipboard - plywood) - 24 mm. The design of the housing includes elements that increase the rigidity of the housing and reduce the amplitude of vibrations of the walls - stiffeners and couplers.
The 75AS-001 uses a set of heads developed for a new generation of high-quality high-sensitivity speakers - 100GDN-Z, ZOGDS-1, 10GDV-4, produced by the Krasny Luch plant. The design of head assemblies using specially developed software packages for calculating their characteristics on a computer made it possible to create effective heads with low nonlinear distortions. Heads are framed decorative overlays, made of ABS-2020 plastic: the LF head cover is round, with six mounting holes, the MF and HF head cover is rectangular with eight mounting holes. Midrange head with inside isolated from the total volume of the housing by a special sealed pipe connecting the front and rear walls of the housing. The heads are located on the front panel symmetrically relative to the vertical axis. At the same time, in order to reduce the unevenness of the frequency response of sound pressure in the frequency range of 1000 Hz, which occurs due to reflection from the front panel of the speakers, the midrange head is installed closer to the upper edge of the front panel, above the high frequency head.
On the front panel, in addition, there is a decorative nameplate with the name of the speaker, the shape of the typical frequency response of sound pressure and overload indicators for the low-frequency, mid-range and high-frequency bands of the speaker; a hole with a diameter of 75 mm, which is the output hole of a bass reflex shell with a length of 91 mm. The geometric dimensions of the bass reflex ensure tuning to a frequency of 36 Hz.
The internal volume of the speaker is 57 liters. To reduce the influence of resonances of the internal volume on the frequency response of sound pressure and the sound quality of the speakers, the speaker housing is filled with effective sound-absorbing material ATM-1.
Electric filters are mounted inside the housing, designed using optimal synthesis methods using a computer and providing, in addition to electrical separation of low-, mid- and high-frequency speaker bands, also correction of amplitude and phase characteristics.
Filters provide band separation: between the bass and midrange heads - 600 Hz; the filter on the side of the bass head is 2 orders, and on the side of the midrange head - 3 orders; between the mid and high frequency heads – 6000 Hz; the filter on the side of the midrange head is 3 orders, and on the side of the high frequency head - 4 orders.
The design of the filters uses resistors of the C5-35V type, capacitors of the MBGO type, and an inductor on plastic frames with “air” cores.
IN speaker system 75 AC-001 has a circuit for protecting speakers from electrical overloads and indicating the presence of such overloads in the input signal.
When a signal appears at the speaker input that exceeds the permissible power for any speaker, the protection device reduces the signal to a safe value for each corresponding head. The occurrence of an overload in any band of the speaker is warned by the glow of indicators on the front panel above the corresponding inscription - LF, MF or HF.
The protection and indication circuits are configured to operate when a real musical signal with a peak power of 75–100 W is applied to the speakers, which corresponds to a sound pressure level of at least 110 dB. When the PROTECTION plug is installed, the circuit is triggered at signal peaks of 300 - 350 W, which corresponds to a sound pressure level of about 116 dB. The first mode provides maximum reliability; the second is the maximum dynamic range and is used when testing for maximum short-term power.
On the base of the speaker there are four plastic legs, and on the rear wall there are terminals for connecting supply wires and a PROTECTION socket for installing a contactor plug that changes (increases) the protection threshold.
After listening to my S-90s for two years, I finally wanted to change them to something better and more powerful. I didn’t want to give thousands of dollars; besides, I had read an incredible amount of laudatory articles on the Internet about the Corvette 75AC-001, which, with appropriate modifications, outperforms many speakers in the price range from 500 to 1000 dollars. So I decided to buy them and remake them.
These Corvettes appear very rarely in Minsk, and after months of studying “Hand to Hand,” I saw the Corvette 150AC-001. All the articles on the Internet unanimously claim that 75AC-001 and 150AC-001 are one and the same, so I happily purchased the long-awaited latter. In addition, the seller stated that this was a converted version and handed me the removed overload protection boards. I was even more pleased because I didn't even have to redo them myself. I checked with the seller the performance of the speakers on his compositions without any attempt to test them for quality, because I was sure that if they were not burned out, they would not play badly.
I brought it home and connected it to my old 20-year-old Sharp amplifier, 80 watts per channel. And oh, horror, the Corvettes played terribly dully, inferior to my S-90s at times! But the lows certainly pleased me with both power and depth. In the end, I decided not to make hasty conclusions before replacing the amplifier and wires - I had simple electrical ones.
My speakers cost so much that I need 12 meters of cable, so I bought a cable for only 2 dollars per meter - Phoenix Gold (super OFC series SS162).
Yamaha A-700 amplifier - 150 watts per channel into 8 ohms, signal to noise 106 dB, intermodulation distortion 0.005%. Nothing changed! I read about the S-90 on the Internet and found out that their highs are too high and the mids are not correct.
The thought came to me - maybe I don’t understand high-quality sound at all, or I don’t have normal hearing at all, and this sound is the right one?
Then I decided to compare them with my Sennheiseh HD-590 headphones - their sound compared to acoustics for $1000 can be considered a reference. Of course, it’s not entirely correct to make such comparisons, but as a result, I realized that the S-90 overestimates the upper midrange and highs, and the Corvette drowns out these ranges to an even greater extent than the S-90 overestimates. After listening to the Corvettes and turning the equalizer, I came to the conclusion that the biggest problem is in the 6-7 kHz range.
There were thoughts of bringing the speakers back to the seller, punching them in the face and taking the money.
But after thinking a little, I decided to open the speakers.
I had this one circuit diagram filter boards 75AC-001 with overload protection.
I also had articles on alterations. Immediately I saw that the coils were on a plastic frame, and not on a board like the 75AC-001.
Further analysis showed that the filter board itself is different.
But after looking more closely, I found some similarities. And then I realized that the seller who remade these speakers, seeing these discrepancies, did not bother further and simply threw away the overload protection board. And in articles on
The modification says that you need to remove several resistors (marked in red on the diagram). Having compared and checked everything, I unsoldered the necessary resistors and soldered the negatives of the speakers to one point. I assembled the speakers and heard that the middle and highs began to sound louder, less drowned out by the lows, but the dip in the 6-7 kHz range still remained.
Then I decided to trace all the tracks on the filter board and draw up a diagram, suspecting that there were some differences. And I found them. Here is the final version of the converted 75AC-001 filter board with marked elements that are simply missing in the 150AC-001.
And here is the actual circuit diagram of the 150AC-001 filter board that I compiled after the rework, and if you look closely, you can see that the values of many elements are slightly different from 75AC-001.
How much impact do these changes have? Maybe it's not the filter board at all? Maybe they just started doing everything badly in 1991?
And so I came across a mention on the Internet about programs that calculate electrical circuits. I found Electronic Work Bench Multisim 7. I downloaded a 70 MB demo version - the limitation of the demo is that you cannot save the file.
I searched for crack for two days, but couldn’t find it, so I decided to just leave the computer on.
It also took several days to figure out the program.
Here's what I got for the midrange. Red line - 75AC-001. Blue - 150AC-001 before rework. Green 150AC-001 after modification.
The sound changed a lot, it was most audible in the voice, but the left speaker sounded somewhat muffled than the right one and then, after experimenting in Multisim, I discovered that increasing the resistance of resistor R2 shifts the cutoff high frequencies to the right on the graph. Experimentally, by ear, the value turned out to be 22 ohms.
This is what I got for the tweeter. The graphs for 150 and 75 coincide by 99 percent.
Here is the graph for the woofer. Red line - 75th, green - 150th.
As I understand it, it's not that scary. It’s just that the 150s in the range of 3.5 - 3.8 kHz will sound somewhat quieter than the 75s. But this range is perfectly picked up by the midrange, so no problems are heard.
As a result, the speakers began to sound much better, but still the mid-high frequencies are not quite enough and this has to be corrected with an equalizer.
On the Internet I came across information that the 75s were still running even in the 90s. My 150s don’t have a date, but the woofers say 91g, 11th month, so it’s most likely that all 150s are like that, but not a fact.
Crossover on the left before the alteration and on the right after.
Here you can see the coil for the woofer and large capacitors for the midrange
This is how I have them arranged for listening; in the bass reflex there is a foam circle about a centimeter thick - this is better for my room.
I hope that this article will at least somehow help the unfortunate owners of 150AC-001 of the same production as mine. Now I'm thinking of trying to find a filter board from 75AC-001 or even finding 75s to 90s. I haven't found it yet.
Despite the work done, the desired result was not achieved.
Manufacturer: NPO "Okeanpribor" (St. Petersburg).
Purpose: acoustic systems of the highest complexity group are designed for high-quality reproduction of music and speech in stationary living conditions.
Specifications:
3-way speaker with bass reflex
Frequency range: 25 – 25000 Hz
Frequency response unevenness in the range 100 – 8000 Hz: ±3 dB
Sensitivity: 91 dB
Characteristic sensitivity: 0.73 Pa√W
Nominal input impedance: 8 ohms
Minimum full value electrical resistance: 6.4 ohms
Nominal effective input power: 35 W
Maximum long-term input power: 150 W
Maximum short-term (peak) power: 300 W
Dimensions (HxWxD): 710x396x355 mm.
Weight: 26 kg
Description:
A distinctive feature of the system is that it has high level characteristic sensitivity and ability to withstand high values electrical power, which allows you to play programs with an extended dynamic range without noticeable distortion.
The speaker body is made in the form of a rectangular non-demountable box made of chipboard, veneered with valuable wood veneer. The thickness of the case walls is 16 mm, the front panel is three-layer (plywood - chipboard - plywood) - 24 mm. The design of the housing includes elements that increase the rigidity of the housing and reduce the amplitude of vibrations of the walls - stiffeners and couplers.
The 150 AC-001 uses a set of drivers designed for a new generation of high-quality, high-sensitivity speakers. The design of head assemblies was carried out using specially developed software packages for calculating their characteristics on a computer, which made it possible to create effective heads with low nonlinear distortions.
The heads are framed with decorative overlays made of plastic. The midrange head is isolated from the inside of the total volume of the housing by a special sealed pipe connecting the front and rear walls of the housing. The heads are located on the front panel symmetrically relative to the vertical axis. In order to reduce the unevenness of the frequency response of sound pressure in the frequency range of 1000 Hz, which occurs due to reflection from the front panel of the speakers, the midrange head is installed closer to the upper edge of the front panel, above the high frequency head. On the front panel, in addition, there is a decorative nameplate with the name of the speaker, the shape of the typical frequency response of sound pressure and overload indicators for the low-frequency, mid-range and high-frequency bands of the speaker; a hole with a diameter of 75 mm, which is the output hole of a bass reflex shell with a length of 91 mm. The geometric dimensions of the bass reflex ensure tuning to a frequency of 36 Hz.
The internal volume of the speaker is about 70 liters. To reduce the influence of resonances of the internal volume on the frequency response of sound pressure and the sound quality of the speaker, the speaker housing is filled with effective sound-absorbing material.
Electric filters are mounted inside the housing, designed using optimal synthesis methods using a computer and providing, in addition to electrical separation of low-, mid- and high-frequency speaker bands, also correction of amplitude and phase characteristics.
Filters provide band separation: between the bass and midrange heads - 600 Hz; the filter on the side of the bass head is 2 orders, and on the side of the midrange head - 3 orders; between the mid and high frequency heads – 6000 Hz; the filter on the side of the midrange head is 3 orders, and on the side of the high frequency head - 4 orders.
The 150 AC-001 speaker system has a circuit for protecting loudspeaker heads from electrical overloads and indicating the presence of such overloads in the input signal. When a signal appears at the speaker input that exceeds the permissible power for any speaker, the protection device reduces the signal to a safe value for each corresponding head. The occurrence of an overload in any band of the speaker is warned by the glow of indicators on the front panel above the corresponding inscription - LF, MF or HF.
The protection and indication circuits are configured to operate when a real musical signal with a peak power of 75–100 W is applied to the speakers, which corresponds to a sound pressure level of at least 110 dB. When the PROTECTION plug is installed, the circuit is triggered at signal peaks of 300 - 350 W, which corresponds to a sound pressure level of about 116 dB. The first mode provides maximum reliability; the second is the maximum dynamic range and is used when testing for maximum short-term power.
On the base of the speaker there are four plastic legs, and on the rear wall there are terminals for connecting supply wires and a PROTECTION socket for installing a contactor plug that changes (increases) the protection threshold.
Manufacturer: 150 AS-001 “Corvette” identical to 75 AS-001 “Corvette”. Produced by NPO "Okeanpribor" (St. Petersburg). The only difference is in GOST standards.
Purpose and scope : for high-quality reproduction of music and speech programs in stationary living conditions. The recommended power of a high-quality household amplifier is 10 - 100 W. The preferred installation option is on a stand 0.3 - 0.5 m.
A distinctive feature of the system is that it has a high level of characteristic sensitivity and the ability to withstand high electrical power values, which allows you to reproduce programs with an extended dynamic range without noticeable distortion. This makes it possible to use 150 AC-001 not only with conventional, “analog” program sources, but also with a digital laser player.
Characteristics
3-way speaker with bass reflex
Frequency range: 25 (-19 dB) – 25000 Hz
Frequency response unevenness in the range 100 – 8000 Hz: ±3 dB
Sensitivity: 91 dB
Characteristic sensitivity: 0.73 Pa√W
Nominal electrical resistance: 8 ohms
Minimum electrical impedance: 6.4 ohms
Noise power limit: 100 W
Limit long-term power: 150 W
Maximum short-term power: 300 W
Weight: 30 kg
Dimensions (WxHxD): 38.6x71x34 cm
Design Features
The speaker body is made in the form of a rectangular non-demountable box made of chipboard, veneered with valuable wood veneer. The thickness of the case walls is 16 mm, the front panel is three-layer (plywood - chipboard - plywood) - 24 mm. The design of the housing includes elements that increase the rigidity of the housing and reduce the amplitude of vibrations of the walls - stiffeners and couplers.
The 150 AS-001 uses a set of heads designed for a new generation of high-quality high-sensitivity speakers - produced by the Krasny Luch plant, which is located in the city of Krasny Luch. The design of head assemblies using specially developed software packages for calculating their characteristics on a computer made it possible to create effective heads with low nonlinear distortions. The heads are framed with decorative overlays made of ABS-2020 plastic: the woofer head overlay is round, with six mounting holes, the midrange and treble head overlay is rectangular with eight mounting holes. The midrange head is isolated from the inside of the total volume of the housing by a special sealed pipe connecting the front and rear walls of the housing. The heads are located on the front panel symmetrically relative to the vertical axis. At the same time, in order to reduce the unevenness of the frequency response of sound pressure in the frequency range of 1000 Hz, which occurs due to reflection from the front panel of the speakers, the midrange head is installed closer to the upper edge of the front panel, above the high frequency head.
On the front panel, in addition, there is a decorative nameplate with the name of the speaker, the shape of the typical frequency response of sound pressure and overload indicators for the low-frequency, mid-range and high-frequency bands of the speaker; a hole with a diameter of 75 mm, which is the output hole of a bass reflex pipe 91 mm long. The geometric dimensions of the bass reflex ensure tuning to a frequency of 36 Hz.
The internal volume of the speaker is 57 liters. To reduce the influence of resonances of the internal volume on the frequency response of sound pressure and the sound quality of speakers, the speaker housing is filled with effective sound-absorbing material ATM-1.
Electric filters are mounted inside the housing, designed using optimal synthesis methods using a computer and providing, in addition to electrical separation of low-, mid- and high-frequency speaker bands, also correction of amplitude and phase characteristics.
Filters provide band separation: between the bass and midrange heads - 600 Hz; the filter on the side of the bass head is 2 orders, and on the side of the midrange head - 3 orders; between the mid and high frequency heads – 6000 Hz; the filter on the side of the midrange head is 3 orders, and on the side of the high frequency head - 4 orders.
The design of the filters uses resistors of the C5-35V type, capacitors of the MBGO type, and an inductor on plastic frames with “air” cores.
The 150 AC-001 speaker system has a circuit for protecting loudspeaker heads from electrical overloads and indicating the presence of such overloads in the input signal.
When a signal appears at the speaker input that exceeds the permissible power for any speaker, the protection device reduces the signal to a safe value for each corresponding head. The occurrence of an overload in any band of the speaker is warned by the glow of indicators on the front panel above the corresponding inscription - LF, MF or HF.
The protection and indication circuits are configured to operate when a real musical signal with a peak power of 75–100 W is applied to the speakers, which corresponds to a sound pressure level of at least 110 dB. When the PROTECTION plug is installed, the circuit is triggered at signal peaks of 300 - 350 W, which corresponds to a sound pressure level of about 116 dB. The first mode provides maximum reliability; the second is the maximum dynamic range and is used when testing for maximum short-term power.
On the base of the speaker there are four plastic legs, and on the rear wall there are terminals for connecting supply wires and a PROTECTION socket for installing a contactor plug that changes (increases) the protection threshold.