Hello all,
Wondering what the general consensus would be on audio signal manipulation, in other words…DSP/EQ. This can be, and often is, absolutely required or atleast desirable due to room acoustics and audio system characteristics. I currently have to EQ by using DSP functionality in Roon. I have also used convolution filters I generated from REW and installed in Roon. Additionally, I have used Dirac through a MiniDSP after room measurements of course. Results have been variable, sometimes quite good.
The resounding feeling I have is one of aversion to modifying the audio signal. Intellectually, even when something sounds right after EQ, I find myself asking “yeah, but what does it really sound like”. This is a major dilemma.
So my question would be which is “less detrimental” to the audio signal - software EQ (such as with Roon) or hardware EQ, including changing for an amplifier with tone controls? Think Accuphase, for example…
By hardware I thought you meant physical room changes and treatment - and that is definitely the best in terms of sound quality, with signal manipulation only when room problems/improvements maximised as far as possible.
I would have expressed it as digital vs analogue EQ. (DSP vs tone controls/graphic equaliser etc). I believe DSP is best (though of course “it depends”: to quality analogue may sound better than poor DSP). DSP can also be far more flexible than any analogue I have come across.
The challenge is the question what are you trying to achieve? and whatever you do do not Try to boost out room cancellations, as that can rapidly lead to speaker destruction without any audible improvement, while with any boosting remember every 3 dB lift will double the amp power whenever the music has notes at the boosted frequencies, reducing headroom before clipping: e.g. what trying to level out just a 12dB trough will drive your amp at 16x the average power for that sound level.
You just give the amplifier a rest at that frequency!
Decibels (dB) are logarithmic, so as IB says you can just add and subtract them up. 3 dB is doubling of the power, another 3dB doubles it again and so on. Other interesting things are that 10dB is ten times the power therefore. So an 80 watt amplifier is only 10 dB more powerful than an 8 watt amplifier.
And people who are used to listening critically will be able to notice a 1dB change in something, for example an increase or reduction in treble frequencies, but an unaware person probably wouldn’t notice 2dB. 10dB is quite a lot, but not really chat much in the scheme of things. If someone speaks quietly and then speaks normally, that is probably 20 dB change or more.
A person who uses hearing aids is probably having to deal with a hearing loss of at least 20dB and possibly as much as 80 dB at some or all frequencies in one or both ears. This is why graphic equalisers aren’t much use to correct hearing loss, even when only one listener is involved. Remember these big numbers still follow the rule of 3dB is a doubling of the power. If you look at the size of a hearing aid battery and think about those dBs, you would be amazed that such a small power source could run something capable of producing that much power increase for a week or more…
Interesting to read your comments. My hearing aids are set up by the audiologist to bring my hearing hopefully back to hearing all frequencies. So some are boosted in the same way as a graphic equaliser.
Yes that is what they try to do, but normally the software only adjusts from about 300 Hz to 8 KHz or thereabouts at specific frequency intervals (“gain handles”) and if the loss is too great, then it can’t compensate as the maximum gain at any frequency is usually around 80 dB. Also there is a maximum output power level than the hearing aid can produce before it gets into serious distortion/clipping. You don’t want to get near that because it sounds terrible. And another big issue with higher gain levels is feedback. Hearing aids have feedback cancelling algorithms but these are not by any means perfect and it’s better not to get near to feedback than to rely on the hearing aid cancelling it.
A particular issue that few audiologists seem to know about is the effect called “entrainment”. The original term refers to a structure vibrating in sympathy with a stimulus, eg troops marching in step over a bridge causing the bridge to sway and keep swaying for a while after the troops stop marching, but in connection with hearing aids it refers to a tone, that the aid produced to cancel feedback, continuing after the feedback stops. This is especially annoying if the tone is not feedback at all, but a flute say, or an oboe. The aid can go on playing the note for a short instant after the musician stops! As it isn’t successfully stopping the flute player, the aid wobbles the frequency/phase a bit to try harder and you can here that too.
Anyway this is a bit off topic, to say the least. But I hope of interest to some reading it.