|Chuck H||11/13/2017 9:40 AM|
|Phase at frequency w/speaker emulator circuit (Juan?)|
I'm working on a passive circuit to emulate speaker frequency response. I'm pretty happy with the EQ but I'm concerned about the phase differential between LF and HF (almost 360*) and was wondering what sort of problems it might cause in actual listening perception or electronically at the input of a mixer/PA. I know that phase error is basically a time lag and if I interpret what I've read correctly I'm dealing with about a 1ms differential. I don't think that's going to be terribly audible, but I don't have much experience with this. Below is a graph of the frequency response of a G12H with the plot for my circuit overlaid on top. Phase is indicated by the dash. It's pretty rough because of the overlay, but I hope the info gets across.
EDIT: Also, does anyone know the real world phase error for an average speaker?
|Mike Sulzer||11/13/2017 1:11 PM|
|If the phase of the speaker response is similar, then I think there is no problem. Do you know the past of the speaker response? There might be no problem anyway; phase often does not matter, but it can.|
EDIt: Not sure what you mean by phase error of a speaker, but speakers have phase shifts just as other electronic components do. In fact the phase response of a speaker can be complicated. I think Eminence has phase plots for many of its speakers.
|Chuck H||11/13/2017 1:56 PM|
|Thank you Mike. By "error" I just meant any differential from ideal. I mean, you wouldn't want your LF appearing 300ms behind the HF. That's extreme and ridiculous of course. Just illustrating. I know Eminence has impedance plots. I'll check there and see if they have phase plots as well. This circuit is strictly for EQ. It won't be a load for anything and it won't be driving anything with current. I did manage to find some speaker phase plots for high end audio stuff and it looks like phase relative to frequency can shift up to 150*. I'll bet a guitar speaker, with it's harder roll off top and bottom is worse. I only wanted to know if there was some inherent problem with phase shifts approaching 180* with a HF/LF differential approaching 360* for EQ purposes.|
|J M Fahey||11/13/2017 3:20 PM|
|What Mike Sulzer said: speakers have terrible phase shift problems, in any case your electronic circuit will always be better than the mechanical version, worst case will approach it, so thatīs what we are used to hearing anyway.|
|Chuck H||11/13/2017 3:27 PM|
|glebert||11/13/2017 3:38 PM|
|Dumb thought: presumably at some point after this emulation circuit someone is going to actually listen to the signal (either directly or from a recording), and they will be doing that through a speaker. If you try to build in the absolute phase response of a particular speaker once it goes through the final speaker you may end up with "extra" phase impact.|
|catalin gramada||11/13/2017 3:51 PM|
|R.G.||11/14/2017 6:43 AM|
|There is a hidden truth lurking under this thread. That is, there can be no filtering without phase shift, at least in analog electronics. The fundamental way that filtering happens is with the interaction of resistive (i.e. no phase shift) elements and reactive elements, things which have a differing impedance with frequency, and that effect by its very nature causes phase shift. The same thing happens in mechanical, acoustic, etc. systems. |
It is probably possible to use DSP programming to affect amplitude as a function of frequency and then to correct signal phase back to no phase shift (or any arbitrary phase shift) but the normal sorts of digital filters also introduce phase shift with amplitude variations.
So if you want filtering, you get phase shift too.
|J M Fahey||11/14/2017 7:10 AM|
That said, using a speaker emulator , which to be more precise should be called a "guitar" speaker emulator , or it would not be needed to begin with, sort of implies that final sound will be played through a Hi Fi, Studio or, worst case, PA speaker ... all of which have (or try hard to) flattest response and minimal phase shifts.
And we add the speaker emulator to that (flat but unexciting) mix precisely to add that off taste flavour we like
|Mike Sulzer||11/14/2017 12:32 PM|