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  • New
    logiclst8
    Newcomer - Level 1
    2022-07-10

    L channel quit all of a sudden. Strange because very low load since purchase. I need to get repared. I live in Maine.

    0 4
    • logiclst8
      CLCarter I have connected my 5 channel mixer, and I have been practicing with it. There a couple of things that I am not sure about
      • Jul 10
    • logiclst8
      CLCarter 1: I have had to increase the gain on my cassette deck to get a reasonable recording. Is this normal? I have temporarily routed the cassette deck to the main output.
      • Jul 10
    • logiclst8
      CLCarter I am blind and I have been trying to work my way around the controls. Is there a more detailed manual that I can use? Preferrably with descriptions of the controls and how they are to be used?
      • Jul 10
    • logiclst8
      CLCarter 3. I found the audio quality to be very good without additional affects. However, I am eager to try using some of the audio functions.
      • Jul 10
    • logiclst8
      CLCarter 4. I want to make sure that that I have the inputs and outputs in the right place. The inputs for the 4 channels are set. It is just the outputs that I am not sure about.
      • Jul 10
  • New
    djtetei
    Newcomer - Level 1
    2022-06-19

    Behringer KM750 specifications state a voltage gain of 32dB. However, if we do the math, the published voltage gain value doesn't add up.

    The specifications states that the KM 750 delivers 200 watts into 8 ohms with an input sensitivity of 0.775 Volts.

    Output voltage formula: sqrt (power x impedance)

    Output voltage calculated: sqrt (200 x 8) = 40V

    Voltage gain (amplification factor): output voltage / input voltage = Av (amplification factor)

    Voltage gain (amplification factor) calculated: 40 V / 0.775 V = 51.62

    Voltage gain (dB) formula: 20log(Av)

    Voltage gain (dB) calculated: 20log(51.61) = 34.25 dB

    The calculated voltage gain is 2 dB higher than the specified voltage gain.

    The only scenario the specified voltage gain is 32 dB is if the input sensitivity is, in fact, 1 Volt.

    Furthermore, if we take the officially specified input sensitivity (0.775 V) and voltage gain (32 dBU) and do the math, we arrive at a different result for the output power of 119 watts, which is less than the officially specified power into 8 ohm load.

    So, the following question arises: when input sensitivity of 0.775 V is selected, the maximum input voltage required for maximum rated power is 0.775 V (0 dBU) or 1 V (+2 dBU)?

    The following scenario applies to Behringer KM 1700, also.

    Update:

    On 29.06.2022, MusicTribe Customer Solutions Specialist Mr Kyle Johnson replied to my support ticket,  and his answer is as follows: "The 200W is the peak power not the RMS, the calculation should based on the RMS 130W for KM750 and 310W for KM1700. Also, the peak power is actually about 210W."

    This is important information and should definitely be included in the product's user manual.

    Starting from this, suppose we now have a peak power of 210W into 8 ohm load.

    Calculate the peak voltage: SQRT(210*8)=40.987 Vpeak

    Calculate the RMS voltage: 40.987*0.707=28.977 Vrms

    Calculate power (RMS): SQR(28.977)/8=104.95 W

    Calculate amplification factor (X) for 0.775 input sensitivity: 28.977/0.775=37.389

    Calculate dB voltage gain: 20*LOG(37.389)=31.454 dB 

    As you can see, the statement about 130 W RMS doesn't hold up.

    Amplifier power is calculated, not measured.

    A Voltmeter measures voltage in volts. An Ammeter measures current in amperes. An Ohmmeter measures resistance in ohms. Any two of these measurements will allow calculation of amplifier power (in watts).

    If you search MusicTribe knowledge base articles, under Behringer brand you will find an article called "What is RMS" with the following statements:

    "We no longer list our amp power ratings by RMS as these tend to not give true results as tests are always done using signal generators and specific waveforms which don't reflect in comparison to music, music comes at fuller frequencies and non linear dynamics which of course as I'm sure you're aware is nothing like a test tone generated from a signal generator...As a rule of thumb, you can assume RMS is around half the peak value."

    Of course music comes with broad frequency range and nonlinear dynamics, because music is mixed and mastered in a specific way, to ensure tonal balance and a specific dynamic range to make it sound good. Its purpose is to be listened and not to be used as a test tone for audio equipment capabilities and limits, although there are certain instruments that can put an audio equipment to the test. On the other hand, test tones are created and used specifically for testing and measurement of audio equipment capabilities and limits. By using test tones and filtered noise waveforms able to stress and measure the audio equipment capabilities and quality of assembly, manufacturers ensure the customer's piece of mind, knowing that when the specific equipment is used with music, it will never reach the operational limits, unless it is used by reckless or unprofessional people. A 0 dBFS test tone with a crest factor of 3 dB is able to push an amplifier or a loudspeaker to its limits, if played long enough, compared to a music track with a crest factor (dynamic range) of about 14 dB, because the latter will never bring an amplifier to its current limits. As many of you know, music is mixed and mastered with different dynamic range, according to the author or the mastering engineer tastes, resulting in dynamic range values between 6 and 20 dB, which makes it difficult to be used as a test reference. You could use music as a test reference if all music tracks are mastered to the same dynamic range (crest factor) target level, but that is not the case. Therefore if a certain audio equipment manufacturer choose to publish peak values for power ratings, it can also publish the calculated average power output relative to the measured RMS voltage output of its equipment, under specifically stated test conditions (proprietary or standardized), and stand behind its statements, ensuring the proper sound system design and implementation for a potential customer. In my experience, failing to disclose usefull information to the customers and failing to provide a solid customer support for parts, warranty and technical feedback is a sure way to destroy a brand's image and affect its business future, even if that particular brand is making good efforts to offer competitive products in terms of functionality. 

    Anyway, as a conclusion, it seems that if you want to match your speakers RMS / continous power rating with a Behringer amplifier power rating, you should expect half of the declared power ratings.

    Therefore, the calculated parameters for Behringer KM 750 and Behringer KM 1700, based on published specifications are as follows:

    Behringer KM 750:

    Peak Power / channel @ 8 ohm: 200 W

    Peak voltage: SQRT (200 X 8) = 40 V

    RMS voltage: 40 X (1 / SQRT(2)) = 28.284 V

    Average continous power @ 8 ohm: SQR(28.284) / 8 = 100 W

    RMS current: 100 / 28.284 = 3.535 A

    Peak Power / channel @ 4 ohm: 400 W

    Peak voltage: SQRT (400 X 4) = 40 V

    RMS voltage: 40 X (1 / SQRT(2)) = 28.284 V

    Average continous power @ 4 ohm: SQR(28.284) / 4 = 200 W

    RMS current: 200 / 28.284 = 7.071 A

    Amplification factor for 0.775 V input sensitivity: 28.284 / 0.775 = 36.519

    Voltage gain for 0.775 V input sensitivity: 20 X LOG (36.519) = 31.250 dB

    Amplification factor for 1.4 V input sensitivity: 28.284 / 1.4 = 20.203

    Voltage gain for 1.4 V input sensitivity: 20 X LOG (20.203) = 26.108 dB

     Behringer KM 1700:

    Peak Power / channel @ 8 ohm: 500 W

    Peak voltage: SQRT (500 X 8) = 63.245 V

    RMS voltage: 63.245 X (1 / SQRT(2)) = 44.721 V

    Average continous power @ 8 ohm: SQR(44.721) / 8 = 250 W

    RMS current: 250 / 44.721 = 5.590 A

    Peak Power / channel @ 4 ohm: 800 W

    Peak voltage: SQRT (800 X 4) = 56.568 V

    RMS voltage: 56.568 X (1 / SQRT(2)) = 40 V

    Average continous power @ 4 ohm: SQR(40) / 4 = 400 W

    RMS current: 400 / 40 = 10 A

    Amplification factor for 0.775 V input sensitivity: 44.721 / 0.775 = 57.742

    Voltage gain for 0.775 V input sensitivity: 20 X LOG (36.519) = 35.229 dB

    Amplification factor for 1.4 V input sensitivity: 44.721 / 1.4 = 31.943

    Voltage gain for 1.4 V input sensitivity: 20 X LOG (31.943) = 30.087 dB

    read more...
    0 61
    • djtetei
      PedroRodrigues Hi djtetei, thank you for your post, In this case I would suggest to submit an assistance request directly to our Tech Support Team via the link below to clarify this matter: https://community.musictribe.com/pages/create-new-ticket?type=Technical%20Support&brand=Behringer Thank you
      • Jun 20
      • Behringer KM750 & KM1700 voltage gain specifications
        djtetei CAS-608741-G1P0W9, opened on 20.06.2022. Still waiting for an answer from your staff.
        • 1
        • ·
        • Jun 27
    • djtetei
      djtetei CAS-608741-G1P0W9, opened on 20.06.2022. Still waiting for an answer from your staff.
      • Jun 23
      • Behringer KM750 & KM1700 voltage gain specifications
        PedroRodrigues Hi djtetei, thank you for your post, please accept our apologies, this matter is being managed by one of our colleagues and we will reply ASAP. Thank you
        • Jun 29
    • djtetei
      djtetei Mr. Kyle Johnson from Behringer staff replied to CAS-608741-G1P0W9: "The 200W is the peak power not the RMS, the calculation should based on the RMS 130W for KM750 and 310W for KM1700. Also the peak power is actually about 210W."
      • Jul 1
  • New
    barriepayne5
    Newcomer - Level 1
    2022-07-04

    Will a Behringer A800 work off a passive pre amp such as the NVA p50sa passive pre amp

     

    Thanks 

    0 3
    • barriepayne5
      djtetei NVA P50 SA will work with Behringer A800 amplifier, but you have to carefully select the input sensitivity and watch the output level from the preamplifier, in order to avoid clipping. Personally, I would suggest using a high quality mixer, with gain control on all inputs, balanced outputs and accurate level meters, between the source / preamplifier and amplifier. Also, take note of the fact that Behringer amplifiers rated power output is published as peak and you can expect the RMS / average power output into the given load to be about half the peak power rating. For Behringer A800 the average power output into 8 ohm load will be 2x110 W / channel and the average power output into 4 ohm load will be 2x200 W / channel. To ensure a 3db headroom between the speakers rated continous power and amplifier continous power, you can use speakers rated to 50W into 8 ohm or 100W into 4 ohm. If your speakers rated continous power is higher than above values, you can run the amplifier at its limits, with no headroom at all or you can look for a more powerful amplifier.
      • Jul 4
  • New
    MattPalmer
    Contributor - Level 2
    2022-06-27

    My inuke stopped working. Starts to fire up but then fan shuts down after a few seconds and all the channels have the red circles. They dont turn orange. Is there a fix or is this amp toast?

    Thanks

    Matt.

    0 64
    • MattPalmer
      djtetei Disconnect the speakers and try to power on the amplifier without any load. If the described symptoms still persists, you may have to open the amplifier for service.
      • Jun 27
      • Red rings of death? Inuke nu4 6000
        MattPalmer Yeah i tried that at home. Still get the red rings. Thank you.
        • Jun 27
    • MattPalmer
      djtetei Focus on power supply and capacitors.
      • Jun 27
    • MattPalmer
      StaffordAV Hi Matt,
      I have an nu6000dsp with the same problem. It turns on and all the dps functions work, but the rings stay red and there is no output.
      I’ve had a quick look at it, and the main ht rails to the amplifier seem to be controlled by a KA3525A switch mode controller. Having checked the data sheet, this has a shutdown facility (pin 10), which should be pulled low to turn on the output. Mine measures at about 4.5 volts, which might be causing the lack of ht voltage. All the other voltage rails are working OK.
      When I get some time I’ll disconnect pin 10 on this ic and tie it to ground with a resistor, and see if I get power to the amplifier; which will then determine the next course of action.
      Not knowing your background, or whether you have any experience at electronic repairs, I can’t recommend just poking around inside the amp, but it is something for you or your friendly tech to look at.
      • Jun 28
    • MattPalmer
      MattPalmer

      My Tech guy said these can't be repaired he said not even by behringer. Little to no support and that they were designed to last 5 to 10 years and I should basically just throw it in the garbage...

      • Jul 1
    • MattPalmer
      StaffordAV If you can get replacement parts, or their equivalents, pretty much anything can be repaired. Whether it makes economic sense is a different matter; probably not for Behringer.

      Regarding the red rings of death. I have now had a chance to look at this a bit more closely. The first step was to remove the KA3525 controller (IC3), and replace it with a socket, which would make experimenting easier. That done I put in a SG3525, which is an equivalent ic. Turned on and it worked; temporarily. Having fitted it into a socket let me easily disconnect pin 10, the shutdown pin, after which the amplifier worked OK. However, as this probably disables all the protection circuitry, not really a satisfactory repair.

      Back in a working state, I was able to test for correct voltages around the circuit. The shutdown voltage is provided by IC2, a 555 timer, whose reset pin is connected to ground through a transistor (T4). When the base of the transistor is low (mVs) the output of the 555 is high (3.5V) and the amp shuts down. When it is working there should be about 4.5 volts on the base of T4. On my amp the voltage here was low, so the output of the 555 high, causing the amp to stay in protect mode.

      The problem turned out to be a transistor (T9), which when the amplifier is turned off pulls the control voltage low enough to trigger a shutdown. Removing this transistor let the amplifier power up properly, but it wouldn’t turn off. T9 is a surface mount npn transistor, which I have replaced, and the amplifier now seems to be working correctly.

      I’m not sure if the original KA3525 ic was faulty, but the total cost of replacement parts was less than £1UK so replacing it was not really an issue.

      I don’t know if this is a common cause of the amplifier being stuck in protect mode, but removing T9 can be done without taking out the psu board, so is an easy first thing to try. Before doing anything else, measure the voltage across C24; it should be about 4.5V on a functioning amplifier.

      The base of T4 can also be pulled low by T2 a thyristor, which is triggered by DC offset voltage on the amplifier output. It is connected to the main amplifier board through an opto isolator; so something else to check if T9 is not the problem. Obviously check that there is no DC on the output and the protection circuit is working properly.
      • Jul 1
  • New
    djtetei
    Newcomer - Level 1
    2022-06-22

    Behringer KM 750 & KM 1700 have positive detent rotary level (gain) controls, traveling between 11 markings on the front panel. How is this scale divided between the 11 markings? How many dB between two markings?

    0 8
    • djtetei
      Dale_M Hi there, this information does not feature in the QSG so I will see if the developers can advise you.
      • Jun 22
      • Behringer KM750 & KM1700 level / gain control scale not specified
        djtetei I would appreciate your answer on this matter, because knowing the dB scale divisions on the gain control knobs is important for matching the amplifier output voltage to the speaker supported voltage. On other amplifiers with selectable input sensitivities, even if the dB scale is not printed on the front panel, it is stated in the specifications sheet.
        • Jun 27
    • djtetei
      djtetei I would appreciate your answer on this matter, because knowing the dB scale divisions on the gain control knobs is important for matching the amplifier output voltage to the speaker supported voltage. On other amplifiers with selectable input sensitivities, even if the dB scale is not printed on the front panel, it is stated in the specifications sheet.
      • Jun 23
  • New
    Shanemorey
    Newcomer - Level 1
    2022-06-18

    Blew an output (B) on the board and am looking for where to find a replacement board.

    0 11
  • New
    nflorend
    Newcomer - Level 1
    2022-06-06

    My Bugera v5 needs repair. Now the 4th week since submitting a claim and no response but automated replies.

    Filed a complaint with Better Business Bureau.

    Department of Consumer Affairs is next.

    1 13
  • New
    shawnlishman
    Newcomer - Level 1
    2022-06-06

    I submitted a ticket on May 17th for an amp that should still be under warranty that needs repair.  Still no response.

    Ticket number : CAS-602097-K0F0Y8

    0 9
  • New
    jamesheyser
    Newcomer - Level 1
    2022-06-01

    I purchased a used C28:4 unit a few months ago and I've had it out a couple of times without issues.

    Last weekend I fired up the system and line checked the monitors (which I power with it) and everything seemed in order. I was setting up mic stands when I heard a quiet "pop", not loud, but noticeable.

    Later on when I went to soundcheck the first act, the amp did not meter any signal coming to it on any channels. At first I thought it was a routing issue with my mixer, but when I put the cable to another amp it produced sound.

    Later in the day when I was telling another crew member about the amp, he said when the small pop happened he thought he smelled something electrical burning, but so subtle he couldn't be sure. 

    So clearly I'm not looking for a "solution", it needs a repair. But I wondered if anyone had any insight on what I might be up against. 

    read more...
    1 18
    • jamesheyser
      Dale_M If the smell of burnt out components has been noted it would be quicker to go to the above support tab and submit a technical ticket so we can assist with the warranty.
      • May 31
      • C28:4 powers up but no signal metered
        jamesheyser I don't have an "above support tab" (perhaps because I'm on a phone).

        I did reach out to the nearest service provider and they declined to give me an RMA because they said they were no parts available. But then they also said that I should reach out to Music tribe, which I also find a little confusing. Perhaps they have an easier time getting parts if the order is processed through music tribe?
        • Jun 13
  • New
    nflorend
    Newcomer - Level 1
    2022-05-19

    Hello Everyone! Submitted a claim through the portal for my amp that is not working after 6 months. That was Monday. Today is Wednesday. Let's see how long this will take :D

    1 7
    • nflorend
      NicJonesMT Hi NFlorend.
      Can you send me your ticket number and I can look into it.
      • May 19
    • nflorend
      nflorend

      One week gone by. Customer support is robots.

      • May 23
    • nflorend
      nflorend

      Third week. Hello?

      • May 30
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