Deqx pre8

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.  

Hi mijostyn, Alan replied back to an mail I sent may 30 on June 3. I figured that he must be swamped between further development and answering user questions. I questioned him because was perplexed at the final response curve that I was seeing. I saw significant dips in the final response curve at the crossover points and moreover, it just didn’t sound right. I also mentioned few items relating to the legacy DEQX-Cal v3 that they may want to consider to eventually integrating into the software. Alan assured me that the response curve we are now seeing with dips at the crossover point(s) is not accurate and in reality those dips do not exist in the actual response. He went on to say the they are presently working to correct that issue.

FYI. I get my best measurements at about 16" (40cm) from the ribbons. For me this yields right at 10mS to the first reflection on each speaker and I set the Trim in the Chirp Config there. I really cannot go closer with the mic since the mid-range to tweeter ribbons are passively crossed over and I’m happy at 10mS. I also set the lower limit of correction to 200Hz and not 20Hz as is the factory default. It probably wouldn’t hurt to go as high as 400 Hz I’m thinking, and I’m sure that I’ll try it eventually.

In the meantime, I did work out the issue of bad sound. The issue turned out to be a slight to sever phase difference between the left and right speaker at different frequencies. I ended up playing with the driver distance relationships under the "Create a Speaker" tab, starting by equalizing the distance left to right of the non-zero drivers. It’s probably not perfect, but it now sounds really good now. I have not integrated the subs as of yet. I’m trying to work out as many of the issues with just the main speaker first before adding a whole new mix of issues surrounding sub integration since it is done way differently than in DEQX-Cal.

Of yes, the Apogees I’m using are the original "The Apogee" which was their very first model with all steel frames and weigh about 300 lbs each.

http://www.reality-audio.com/full_range.html

Oh, one more thing. Does anyone know how to do a Volumio Plug-in on the Pre-8?

I opened a ticket with Volumio  about two weeks ago but it's still in the "pending" state.

@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. 

mijostyn, Im glad that you pointed that out to me. You got me thinking. Even though I used lots of very sound absorbent padding on the floor, walls, etc, and I’m sure that the cloud processing uses software algorithms to minimize first reflection interactions, I’m still about six feet from the side walls and just under four feet from the floor with the mic. I just now took another very close look at the impulse response in Lin X mode and i noticed some rising "fuzz" on the decaying curve starting at about 5.5mS. That’s probably more realistic. Later tonight, I’ll go back and run it through to the end and take a listen. I appreciate the heads up!

Oh no, I didn’t want to hear that about the Volumio installation. I was hoping to use the Softsqueeze plugin in order to use LMS (formally known as Logitech Media Server) directly to Volumio. Right now, I’m using LMS with the UPnP/DLNA Bridge plug in (on the LMS side) developed by an LMS community member.. It works but making a connection isn’t always smooth when connecting to Volumio. Sometimes you need to mess around with it to get it working.

@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.