out at 4ft from the coax. the drivers measure somewhat more true to spec. Still a heck of a roll off on the CD.
Looks like a third order 4K low pass on top of the usual first order roll off of a constant directivity horn/driver response, 24dB octave acoustic rolloff.
Did you verify the output of your DSP (and amp) have flat amplitude response, same voltage output at 1kHz through 20kHz?
Finally, back with some data and good news, and bad news.
The Good:
Measured all components in the system. DAC, Amp's, Pre, all within measurement error (+/-0.1dB) on the oscilloscope. The Dayton DSP-408 rolls off slightly at 20k
The other good. I re-eq'd the CD using this article from our good friend Rod Elliott as inspiration. Instead of trying and shelfing up and down in the last few octaves this is based on high passing with a 6dB slope at 15-20k. 17.5k sounds good to my ears right now. This makes it much easier to adjust for the slight roll off in DSP as it approaches the XO freq. This approach immediately gave a much more natural sound presentation, more soundstage and eliminated the fatigue (I thought this was just how the CD's were until now).
With explanation in "The Bad", below, I also now have a decently response. I never got a chance to measure the Yamaha amp but perhaps it was getting on its way. Although strange since the bookshelves with passive XO measured great on it.
The Bad:
The main amp in my Yamaha RXV-850 is now dead 🙁 . After verifying ground was ground, etc... and doing all the right things to not blow up my scope, distracted and in a hurry a swapped connection was made. The receiver turned off from its own protection but the O-scope channel survived. The diagnostic code results in "unexpected current" . After some preliminary investigation, no internal fuses blown, one channel barely working, and nothing obviously blown or hot. The pre section is still good and measures well. Its a 50W pre-amp now.
In the Yamahas place is now a Hafler SE-240 (ugh, another 75W of idle heat). This has uncovered another source of noise. At first, I thought that the XLS-1000 was just noisy and causing hiss in the woofers (audible at LP). Now being able to turn off the CD amp I can isolate the noise to when the XLS1000 is on. After a disconnecting spree, line levels are ruled out. Disconnecting the woofers from the XLS remove the noise, as does turning off the Hafler. Clipping around with chonky ferrites has no affect. I has a guess that the noise is getting coupled in the 10-12ft of 14/4 feeding the speakers and getting re-amplified by the Hafler (CD) amp. Not sure what I'm going to do as a cure yet. My XLS-2502 that does sub duty has its speaker cable running bundles with the speakers and it has no influence on noise. Perhaps some additional passive LPF on the XLS1000 outputs? Twisted pair speaker cabling for less x-talk?
Moving the mic around left and right a foot in the LP suggests that the response is much less ragged than it looks and HP rolls off quickly off axis so doesn't sound as bright as it looks in the 8-15k area. I still have some HS (6dB slope) at 10k that I can pull out if if sounds bright after some listening.
The Good:
Measured all components in the system. DAC, Amp's, Pre, all within measurement error (+/-0.1dB) on the oscilloscope. The Dayton DSP-408 rolls off slightly at 20k
The other good. I re-eq'd the CD using this article from our good friend Rod Elliott as inspiration. Instead of trying and shelfing up and down in the last few octaves this is based on high passing with a 6dB slope at 15-20k. 17.5k sounds good to my ears right now. This makes it much easier to adjust for the slight roll off in DSP as it approaches the XO freq. This approach immediately gave a much more natural sound presentation, more soundstage and eliminated the fatigue (I thought this was just how the CD's were until now).
With explanation in "The Bad", below, I also now have a decently response. I never got a chance to measure the Yamaha amp but perhaps it was getting on its way. Although strange since the bookshelves with passive XO measured great on it.
The Bad:
The main amp in my Yamaha RXV-850 is now dead 🙁 . After verifying ground was ground, etc... and doing all the right things to not blow up my scope, distracted and in a hurry a swapped connection was made. The receiver turned off from its own protection but the O-scope channel survived. The diagnostic code results in "unexpected current" . After some preliminary investigation, no internal fuses blown, one channel barely working, and nothing obviously blown or hot. The pre section is still good and measures well. Its a 50W pre-amp now.
In the Yamahas place is now a Hafler SE-240 (ugh, another 75W of idle heat). This has uncovered another source of noise. At first, I thought that the XLS-1000 was just noisy and causing hiss in the woofers (audible at LP). Now being able to turn off the CD amp I can isolate the noise to when the XLS1000 is on. After a disconnecting spree, line levels are ruled out. Disconnecting the woofers from the XLS remove the noise, as does turning off the Hafler. Clipping around with chonky ferrites has no affect. I has a guess that the noise is getting coupled in the 10-12ft of 14/4 feeding the speakers and getting re-amplified by the Hafler (CD) amp. Not sure what I'm going to do as a cure yet. My XLS-2502 that does sub duty has its speaker cable running bundles with the speakers and it has no influence on noise. Perhaps some additional passive LPF on the XLS1000 outputs? Twisted pair speaker cabling for less x-talk?
Moving the mic around left and right a foot in the LP suggests that the response is much less ragged than it looks and HP rolls off quickly off axis so doesn't sound as bright as it looks in the 8-15k area. I still have some HS (6dB slope) at 10k that I can pull out if if sounds bright after some listening.
Attachments
As the old electronics adage applies, "check the stupid obvious first". The XLS1000 noise problem is solved! Turns out the ground conductor in the IEC cable was bad. Cut up and trashed that death trap and replaced with a new cable. Problem solved!!!
I should probably look at upgrading the Hafler to a grounded mains input and add chassis grounding now. Eeek!
I should probably look at upgrading the Hafler to a grounded mains input and add chassis grounding now. Eeek!