gnarly

Yep, that's the question alright! My experience so far has been the flatter i get phase the better. By flatter i mean zero degrees flat, or linear phase. The improvement in sound seems to mainly be built off a clearer bass foundation. But, and a pretty big but, I've come to realize how the higher tap count also increases frequency resolution, which appears to matter down low. For example, an OpenDRC with 6144 total taps at 48Hz with impulse centering for linear phase, has a resolution of 15.6Hz (48,000 / 3072). Whereas a Qsys Core with 16384 total taps at 48k has a 5.9Hz frequency resolution. (48k/8192). (I'm pretty sure you know all this quite well, but thought i should illustrate for others who might be following along.) So how much of the improvement in the bottom end is due to flatter phase, and how much is due to increased resolution, I can't say. Since both notes and transients seem improved, i have to believe both factors matter. Given that FIR filters can have the impulse peak wherever within the tap count, even at the beginning for pure IIR emulation, I've been playing with moving the impulse away from linear phase center and peak closer to start, trading off phase flattening capability for increased resolution. Hopefully this will help determine what matters most, in what situations.

Yes! 😄 I have done so much of that. So much.... Both indoors and out, trusting the sound of outdoors waay over indoors. Percussive transients, which i take equals full range response, are such a great listening test. It's one of the ways I think flat phase smokes the typical phase wrapped signal. All the voltages of the frequencies contributing to the transient's response stack together for a higher voltage peak when in phase.. Easy to see on a scope, easy to hear. So far, traditional dual-channel measurements that have both flat mag and phase, have no doubt for me, provided the best transient (and tonal) response. (For tonal response, this is ignoring house curves, and track-by-track tonal biases.) But i'm always in search of the better measurement mousetrap.....that leads to better sound. If you have a measurement technique that can pinpoint transient acoustic ringing problems, I'm all ears !

Cool. No arguing from here either. My testing has been with the usual dual-channel pink, or pink periodic. Or sine sweeps ala REW. What transients would you suggest testing with? Maybe wavelets? I've just starting using them..

I know nothing about video delaying. But sure have used a lot of different audio FIR platforms. Right now, using Q-Sys with Core 110f and 500i processors. Before that, 4 OpenDRC-DI's. Before that, Jriver using multichannel convolution via Config File. Before that, an OpenDRC-DA-8. So a long time journey with FIR 😀 Jriver is a great way to wade in imo.

Agreed, other than as to significance. I've made extensive on and off axis measurements outdoors on numerous 3-way tops using the described process, and found off-axis holds up very well. Evidently, there is very little cancellation that needs to occur. Off-axis measurements are simply quite good; wouldn't they show that uncontrolled energy? I probably need to stress the degree of care taken with the pre-xover, driver-by-driver min phase, out-of-band flattening work. It is essential ime/imo. Without it, i would expect response problems in the exact nature you describe. It's the same problem with linearizing phase on top of an existing speaker with xovers already in place. I should restress how much steep xovers have helped pragmatic driver-by-driver work, to get both on and off-axis to hold together. When an acoustically complementary design is achieved, i have to view pre-ringing from linear phase xovers, even steep ones, as a total non issue.

Hi! True, for one sided filters, high-pass or low-pass. But my understanding is not true for complementary linear phase xovers, where both pre and post ringing cancel each other out. I feel complementary linear phase xovers are probably the most overlooked no-brainer way to increase SQ out there. (along with concomitant mutli-amping etc) Of course it's easy enough to achieve fully complementary xovers electrically, but quite a bit to harder to achieve them acoustically. Since a speaker needs to be acoustic complementary to avoid ringing, I'm an advocate of getting the drivers as complementary as possible pre-xover. By using minimum phase EQs driver-by-driver to flatten mag and phase within the drivers' pass-bands like as always done, but also continuing such flattening through the drivers' xover summation regions. Then just add complementary linear phase xovers to tie the drivers together. I've found steep xovers minimize the out of band min-phase mag flattening needed, which is always the most difficult task. And it 'undoes' nearly all the out-of-band mag boost that flattening required , which could otherwise harm drivers. Steep also reduces the width of the xovers summation, reducing the freq range of off-axis lobings. And bingo...relatively (if not completely) flat phase, with no ringy dingy !! Anyway, my 2c thoughts 😃

Haha, I like this !! I'd call myself a mossback who's seen the light 😀 Been a heavy FIR user for about 6 years now.

Yeah, that would have made it really huge with double 15"s It was titled "synergy...take#7. The foamboard flares don't enter the thread until post 30 something. https://www.diyaudio.com/forums/multi-way/351670-synergy-7-a.html A good picture of how the curved foamboard bolts to the horn is at bottom of this post. https://www.diyaudio.com/forums/multi-way/362087-somewhat-easier-build-synergy.html Thx again, and good luck...hope you don't even need the subs😀

Thanks ! ! Yes, the horn is regular flat baltic birch, and the curved flares are detachable. They bolt onto the outside, and would not have been strong enough at all, without being fiber glassed. Wood horn has mouth of 33x19, flares add up to about 49x29 (90Hx60V) And yep, they are double 18" slot-loaded bass-reflex subs. One more yes, 😀 i'm mark100 on DIY. 100Hz and single round centered port has worked well on several tries. So have corner ports but I haven't found any advantage to them yet. Where are you planning to cross to the subs you have in mind?

Hi StabMe, and all, Super nice project ! Looks very well made! Looking forward to your listening impressions 😀 I guess i maybe got inspired the same way you did, by ChrisA's praise of his K-402 MEH, and the clone-like build by the Australian fellow named Oohms........ My build uses curved XPS foamboard secondary flares, wrapped with glass cloth and epoxy, to try to match the geometry Oohm layed out. Think I got reasonably close, but yours is no doubt a better match. Anyway, mine use a bms4594he CD, crossed to a pair of faital 10pr300's at 500Hz. All my speaker builds are designed to cross to subs at 100Hz, so I didn't need anything bigger than 10"s. It looks like your port size is about 1/10 Sd. Is that correct? 1/10 has been my stand ratio on a handful of MEH builds, using 12", 10", and 8" low/mids. How high do you plan to run the 15"s ?

Understand, makes sense..cool to have such moderation in place. And there's no reason for me to repost the product links....they were out of simple courtesy, to keep someone from having to search.

Sorry, my bad. I saw the link in a previous thread to the qsc 8 ch amp., and thought product links were aok. But i now see the link is a spec sheet....so i guess pure specs links are fine, anything else is a no-go?

Hi all, new poster here. May I first say, it's been very enjoyable and informative studying many threads and posts on these klipsch community forums. Hope to try making a DIY K-402 MEH soon ! Maybe in exchange i can provide some info about the qsc amp that Chris A linked... I'm familiar with the QSC CXD-Q amplifiers, owning a couple of the 4 channel models. They are network amps that connect via Ethernet to a QSC Core processor. A Core processor is mandatory. QSC makes a number of different Core processors, with the smallest, the Core110f being the most flexible in terms of built in I/O capability. Unfortunately, I'd be reluctant to recommend any of the CXD-Q amps for home use, simply because their fans are loud. It's a crying shame because they do provide a multi-channel digital signal flow solution, between processor and amps. The Core110f processor however, I can wholeheartedly recommend to anyone looking for a multi-channed dsp. It uses the Q-SYS Designer software to make open architecture processing schematics. The flexibility is awesome....you can design just about anything. I'm running 8 channels with 4096 taps of FIR on each channel. Along with traditional IIR EQ banks, timing, levels, peak and rms limiters, etc. It has 8 balanced mic/line inputs, 8 balanced mic/line outputs, and another 8 channels that can be independently configured as inputs or outputs. USB 16x16. It's silent too About the only negatives are no AES/spdif inputs, and 48kHz only. Another network amp solution with Q-SYS is to use what QSC terms an I/O frame and connect to any of their amps which have data-port connections. The amps are their CX install series, and Powerlight touring series. The only issue with these is the damn fans in the I/O frames are also loud. Not nearly as loud as the CXD-Q amps, but not quiet either. I got my q-sys stuff off ebay. It's robust enough I feel used is fine. The Core110f typically trades for $1200 - $1800, from used to like-new. The CX amps go for peanuts compared to new. Previous processing rig was 4 openDRC DI's connected to an 8 channel Midas digital I/O/DAC box. Worked super, but at twice the cost of the Core110f, and not nearly as flexible. Apologize if I sound like a q-sys shrill....it's just it's so dang hard to find the processor we need...and when we do !!