Amplifier pairing with APT Holman

[rdenney]

What do you mean by "constant Q"? For each frequency, the user can adjust the amplitude and the Q with the Yamaha.

There are lots of products out there that can do digital parametric equalization effectively--I was just responding to the notion that it had to be expensive.

Rick "has two of the Yamahas, used for general EQ not subwoofers" Denney

 

[Mark185]

@rdenney I am not criticizing you or your recommendation. Apparently, I did not read the test review of the Yamaha unit completely. I focused on a part of it showing test results with constant Q behavior. If Q is adjustable and stays at that value no matter how much boost or cut, that is outstanding and an even stronger argument for the Yamaha as a cost effective solution. Apologies if you thought I was criticizing you.

 

[rdenney]

@rdenney I am not criticizing you or your recommendation. Apparently, I did not read the test review of the Yamaha unit completely. I focused on a part of it showing test results with constant Q behavior. If Q is adjustable and stays at that value no matter how much boost or cut, that is outstanding and an even stronger argument for the Yamaha as a cost effective solution. Apologies if you thought I was criticizing you.

I haven’t investigated how Q might change with amplitude and one thing I haven’t figured out is how Yamaha calculates Q, or what units they used for the quality factor. I didn’t know what you meant by constant Q, which is why I asked. Q is adjustable, and I adjusted it by trial and error, but that isn’t very systematic. Yamaha’s number does not align with REW’s—that much I remember from when I analyzed the system, so it’s worth noting. I took no offense at all.

Rick “all good” Denney

 

[Mark185]

Q is actually a dimensionless number so there are no units. It is related to the bandwidth of the adjustment. Constant Q means the bandwidth of the adjustment does not vary with the amount of boost or cut. A constant Q equalizer was somewhat rare 20 years ago. Most consumer level equalizers had Q values that changed with the amount of boost or cut and it was unpredictable and not something you could control. All you could do is change the boost or cut and live with whatever bandwidth resulted.

Modern digital equalizers allow you to change the Q and it will remain at that value no matter how much you boost or cut. It is interesting that Yamaha's Q does not align with REWs. It should.

 

[rdenney]

Q is actually a dimensionless number so there are no units. It is related to the bandwidth of the adjustment. Constant Q means the bandwidth of the adjustment does not vary with the amount of boost or cut. A constant Q equalizer was somewhat rare 20 years ago. Most consumer level equalizers had Q values that changed with the amount of boost or cut and it was unpredictable and not something you could control. All you could do is change the boost or cut and live with whatever bandwidth resulted.

Modern digital equalizers allow you to change the Q and it will remain at that value no matter how much you boost or cut. It is interesting that Yamaha's Q does not align with REWs. It should.

I recall after some thinking and knob twirling that Yamaha’s formula is the usual center frequency divided by the bandwidth, with an allowable range of 0.5 to 10. That number does not change with adjustments of frequency or gain, but it is, of course, adjustable over that range. What I don’t know is how Yamaha estimates bandwidth. Is it at +/- 3dB? That would be normal, but I don’t know.

It may be that REW simply wanted steeper filters than the Q of 10 that is the Yamaha’s limit.

I also seem to recall that REW uses a statistical calculation to estimate bandwidth, given that it is a recommendation from measurements of a sweep rather than a setting for a digital filter that is applied to the arbitrary input signal.

The Yamaha has six standard parametric filters, four notch filters, and high and low shelving filters for each channel. It is limited to selections—the frequency setting scale is not continuous to the Hz.

Each channel can also be delayed, but I think the scale resolution there is 100 microseconds, so it would be fine for crossing over separate subs but it’s not intended to be an active time-aligned crossover between woofers and tweeters. That feature is used for PA systems with physically distributed loudspeakers.

So, it’s not perfect, but it’s still quite good and useful for general EQ duties outside an intentionally reverberant room.

Rick “the devil is in the details” Denney

 

[Mark185]

I wish I knew about the Yamaha before I wasted $$$ on a Behringer DCX2496 and some audiophile tweaks designed by Jan Didden to improve its SNR. It is clearly a better DSP than the Behringer. The DCX was my first experiment with DSP years ago. I mainly used it as an active crossover.