Deqx pre8

@caglioti 

You should be able to tailor your curves with the EQ function. I roll the top end off from 1000 Hz amount depending on the volume. I put a corner at 20 kHz. and sweep the Q all the way over as far as it will. Then all I have to do is move the corner (or very low Q filter) up or down depending on the roll off suitable for the situation. I also EQ the bass up 10 dB at 20 Hz. What are you using for speakers? 

@forrestc 

I was not expecting plug and play at all. However, there are a lot of bugs and idiosyncrasies. The basic functionality is there and you learn your way around the idiosyncrasies. What worries me most is the lack of communication lately. Something happened. Hopefully nobody is ill or hurt. Maybe they are just tired of listening to me b-tch. 

ESLs have an extremely light diaphragm. It is transparent to reflections. You can hold a perfectly normal conversation with someone standing behind the speaker. The microphone picks up everything coming off the back wall and assumes it is coming directly from the loudspeaker. The curves are a beautiful example of comb filtering from 500 Hz up it looks like waves with +3-4 dB peaks.  Anyway, I'm building the solution. Not much above 200 Hz is going to get by this device. 

This is my first DEQX. I used a TacT 2.2X for 20 years. About a year ago it died. The 8 was not available yet. I got a MiniDSP SHD to hold me over. Dirac Live works surprisingly well and for $1500 the SHD is an amazing value, but it's DACs are not up to the quality a top system demands. Benchmark Media systems uses a SHD Studio with their own DACs and are very happy with the results. The SHD is now in a friend's system. The DACs in the 8 are top notch and even in bypass mode it is sonically superior to the SHD. 

@forrestc 

The problem comes with the first step, defining the drivers. In this mode the DEQX assumes everything is coming from the driver. It uses this measurement to determine what is room effect and what is the driver. Getting a near anechoic measurement on a dipole is next to impossible unless you drag them outside. Remember, dipoles rediate in a figure 8 fashion and sharply beam vertically. You only have to worry about the rear wall and reflections coming from it.  I tried blocking the rear wave with a quilt draped over a tall tripod. It worked up to about 1000 Hz then the comb filtering resumed. I am going to build a 24" wide "Sallie" 7 feet tall which should do the trick. If I can't get a decent measurement then I'm afraid that will end my relationship with DEQX. 

@forrestc I have a problem with volumio. I reached out to Volumio and they referred me back to DEQX who have not been helpful either. I use Volumio to plug in Qobuz which works everywhere in my house except on the Pre 8. I went to up date Volumio as I was behind in versions. The unit crashed during the update. I reset it to factory settings and now other than the volume control the front panel does not work. I operate the system from my computer. There is a set up procedure for Volumio and I assume until this is done the Volumio attached functions will not work.

You are right staying back from the midrange and tweeter ribbons. Tri amping that speaker is difficult because the impedance of the individual ribbons is close to zero. My Divas had a huge back of resistors to compensate. 

10 ms is 10 feet. You are 10 feet from the rear and side wall? 

I see the same problem at the crossover points. I always check the results with an independent USB measurement system and there is a dip in the response at the high frequency crossover points. This only occurs at the midrange/tweeter crossover. The subwoofer cross seems normal although the delays on the subwoofer are OTL (Out to Lunch). 

I also have a phase problem. Usually, one of the high frequency channels will be 180 degrees out of phase, but it can happen with a lower frequency channel. I set the microphone positions with a tape measure. I have no idea why this is happening. 

I have not used any previous DEQX models. I used a Tact 2.2X for 20 years and it's correction system was faultless. It also offered much more flexibility, but the unit finally expired and the company is out of business. I looked at the Trinnov Amethyst, but I did not think it's bass management was flexible enough. 

Hi Fellows,

I was in the first wave. There was a plan to set up a forum for users. Have either one of you tried to contact DEQX lately. They have not answered any of my inquiries for three weeks. I'm a bit worried that COVID took to much of a financial toll on them. 

I have a difficult system for the Pre 8. I use dipole ESLs and the comb filtering they produce confuses it. I'm working on a solution to absorb most of the back wave so the 8 can get a measurement on it.

@caglioti you are right. we need more flexibility, manual control of delays and separate EQ for each channel. Right now I have set the crossovers and run it in manual mode, EQing manually. The imaging is not yet what it should be. Rome was not built in a day.
 

@forrestc Which Apogees? I use to have Divas. You have the same basic problem I have, Dipoles, perhaps not as bad as mine as the ribbon is not as transparent to the rear wall reflection. Place the microphone as close as you can to the ribbons, within and inch!  Look at the response curve. If you see it bouncing rhythmically along the x axis you are picking up the comb filtering.  If you go to the Sound Labs web site check out the "Sallie" rear wave absorption panel. I am building a 24" wide version with 8" wedges instead of the stock 6" wedges. If you are not comb filtering then it is a mute issue and you should be able to get a decent measurement.