Multiple signal generator with broken filter

signals.mm

    // MULTIPLE SIGNAL GENERATOR!
    __block float *phases = nil;
    __block float dbVal = 0.0;
    __block float *dbData;
    [audioManager setOutputBlock:^(float *data, UInt32 numFrames, UInt32 numChannels)
    {
        float samplingRate = audioManager.samplingRate;
        NSUInteger activeSignalCount = [tones count];
        
        // Initialize phases
        if (phases == nil) {
            phases = new float[10];
            for(int z = 0; z <= 10; z++) {
                phases[z] = 0.0;
            }
        }
        
        // Multiple signals
        NSEnumerator * enumerator = [tones objectEnumerator];
        id frequency;
        UInt32 c = 0;
        while(frequency = [enumerator nextObject])
        {
            for (int i=0; i < numFrames; ++i)
            {
                for (int iChannel = 0; iChannel < numChannels; ++iChannel) 
                {
                    float theta = phases[c] * M_PI * 2;
                    if (c == 0) {
                        data[i*numChannels + iChannel] = sin(theta);
                    } else {
                        data[i*numChannels + iChannel] = data[i*numChannels + iChannel] + sin(theta);
                    }
                }
                phases[c] += 1.0 / (samplingRate / [frequency floatValue]);
                if (phases[c] > 1.0) phases[c] = -1;
            }
            c++;
        }
        
        // Normalize data with active signal count
        float signalMulti = 1.0 / (float(activeSignalCount) * (sqrt(2.0)));
        vDSP_vsmul(data, 1, &signalMulti, data, 1, numFrames*numChannels);
        
        
        // Apply master volume
        float volume = masterVolumeSlider.value;
        vDSP_vsmul(data, 1, &volume, data, 1, numFrames*numChannels);
        
        // Filter
        float *coefficients = (float *) calloc(5, sizeof(float));
        float filterFreq = samplingRate/2.0f;
        float rc = 1.0f / (2.0f * M_PI * filterFreq);
        float alpha = rc / (rc + (1.0f/samplingRate));
        coefficients[0] = alpha;
        coefficients[1] = -1.0f * alpha;
        coefficients[3] = -1.0f * alpha;
        vDSP_deq22(data, 1, coefficients, data, 1, numFrames*numChannels);
        free(coefficients);
        
        // Measure dB
        dbData = new float[numFrames*numChannels];
        
        vDSP_vsq(data, 1, dbData, 1, numFrames*numChannels);
        float meanVal = 0.0;
        vDSP_meanv(dbData, 1, &meanVal, numFrames*numChannels);
        
        float one = 1.0;
        vDSP_vdbcon(&meanVal, 1, &one, &meanVal, 1, 1, 0);
        dbVal = dbVal + 0.2*(meanVal - dbVal);
        dBlevel = dbVal;

        if (dbVal != dbVal) {
            //nan
            dbVal = -50;
        }
        
        
     }];