coolhandjjl

I have been looking at lots of pics of cutaway k horns, diagrams of the pathway out of the k horns bass horn. Is the chamber behind the woofer sealed? That narrow rectangular opening right in front of the woofer, is that some sort of phase plug for the horn?

I've seen guys dovetail plywood. Just because they could. It's all up to you. We all have our own quirks and obsessions when it comes to craftsmanship.

I would think mitered cuts would be the hallmark of a master woodworker. Not sure what the OP has for experience.

I build cabs for pro use, so this would hold true for anything. I use 1/2" Baltic Birch with a simpe butt joint. Baltic Birch is used as it is one of the more void free plywoods. With properly engineered internal bracing, 1/2" plywood is more than adequate, but I do feel vibrations on the cab. For home use, that may be problematic if it is used as a coffee table or similar. You can certainly use 3/4" plywood if you want. The key here is to make sure the plywood is rated as void free. Don't get 12 layer plywood with paper thin outer veneer either. I use Loctite PL Premium urethane adhesive along the joint with a fillet along the inside of the cab. No need for biscuits, dados, rabbets, dowels, cleats or screws, it is plenty strong as is used at concert level SPL's. PL Premium is used because it slowly creeps into the joint as it cures, sealing any gaps from potential air leaks. However, cleats installed ahead of time, or shallow rabbets can be useful for positioning each panel so the plywood with its wet glue joint doesn't slide around while being clamped My cabs' side and rear panels get covered with Tolex, whether it's a vintage Fender Tweed, or a basic leather-like texture Tolex. I finish my motor boards with shellac right over the birch plywood, or I dye the wood first depending on the style, then use shellac. All joints need to be masked so squeezed out glue does not stain the wood where you would see the joint when finished. You may want finish with some edge banding over the exposed plywood edges for cosmetic reasons, so plan ahead and adjust the size of your panels at those joints to allow for the thickness of the edge band. Or veneer the entire finished cabinet and you do not have to be so vigilant regarding little messes along the joints as you glue. There is lots of discussion on alternative void free plywoods and use of PL Premium here: http://greenboy.us/forum/

400Hz is where I am dialed in, handles it no problem. If I decide to swap out to the B&C DCM50's, and you decide on the Radians, let me know.

The main reason I was tinkering with two way configuration was that in the future, I'd like to build a tube amp, and if the tube amp drove everything from 400Hz~20kHz, I assummed that would cover the tubiness listening enjoyment, rather than having it just drive my current MF configuration from 400Hz ~ 6000Hz. I considered a three-way bi-amp system with MF and HF passively crossed, but the Radian is so efficient in the Eliptrac 400 horn, there's no tweeter that can keep up with it. Given that, there's no hope of running a steep slope network between it and a tweeter, as the networks that ALK designs to attenuate the MF is a gentle slope network. Right now, I am enjoying it as a three-way tri-amp system. The MF and HF mesh nicely together, dispersion seems matched (by ear), no noticeable lobing (by ear), or listening fatique. Here's a brief description of my drivers and amps with efficiencies listed as provided by the designers/manufacturers: 20~400Hz: Horn loaded bass bin+Eminence 3012LF x 2 (105dB). SAE 2401 350WPC ss amp into 4Ω /3V input sensitivity. 400Hz~6000kHz: Eliptrac 400+Radian 950PB w/aluminum diaphragm & mylar surround (111dB). SAE A201 100WPC ss amp into 8Ω/3V input sensitivity. 6kHz~20kHz: Selenium HC23/25+BMS 4552 w/mylar diaphragm (113dB). Carver PM300 100WPC ss amp into 8Ω/.775V input sensitivity. Crossover is a TDM 24CX-4 (Madisound private label version) configured as stereo 3-way. 24dB/octave Linkwitz-Riley style. Installed as they are, my active crossover has my LF and HF dialed to equal output levels, MF is dialed down a bunch (no dB scale available on its output setting). With different amps of different sensitivities, and different load impedences, it's hard to compare what is really going on with actual driver sensitivities vs true output. Based on the sensitivities I posted, you'd think the HF was the one to be attenuated, but I swapped the amps for my MF and HF during testing, and the MF always needs to be strongly attenuated at the crossover. In the future, if I ever do get that tube amp, I might consider swaping the mid driver for one of much lower sensitivity so it can be passively steep slope crossed with the tweeter, and go to a bi-amp, 3-way system. Something like the B&C DCM50 could fit the bill. But right now, it does sound mighty fine!

I don't know if that has an audio term. Using the term Ground Lift or Lifting the Ground in audio circles assumes a setup that involves three wire audio signal connectivity (plus, minus, outer shielding) between the source all the way through to the power amp, and specifically refers to removing the shield connectivity of your audio signal on one of the components. Don't want anyone to get fried here.

How do you do a ground lift on a system with unbalanced interconnects? Did you build your system with XLR or TRS interconnects?

They are smooth, but not final sanded yet. I also need to wait until the weather warms up to spray paint outside. The reason for the Radians? I did not initially plan on a two way. For future use, drivers that 'could' operate as a two way appealed to me, but not 100% necessary. Al at US Speaker told me that the Radian 950PB was his most popular driver, even for audiophile use. He stressed the aluminum diaphragm with mylar surround as being more pleasing than titanium for some people. I did some EQ boost during some tests, and got the response graph to level out. But for some reason, I just like my system as a three way, so I went back to that. There's just a little bit of extra snap or something, may it's placebo, who knows?

Nothing wrong with your observations. My test were done somewhat quickly, I'm sure I have way too may variables in my methodology to be taken as gospel. Graphs from ALK and Crites are professionally created, mine are not. Also, I didn't have my hearing protection with me that day, so I really didin't want to push it to 105 or higher anyway.

I do know that performance characteristics of some drivers vary greatly as the SPL increases, but when is the last time anyone in a non-event setting ran their tweeter up to 105dBs?

The graph does show it well, but I want to do some listening to make sure it sounds well too. Since this is an all horn system, I'm careful about horny or honky-like tones. That frequency area can be a funny one, so if it adds any hint of honkiness, then I will go back to the former state.

I did some testing on the Leviathon today. For those who haven't followed my madness, it's a 3-way tri-amp system with Dave's Eliptrac 400 as the mid horn, and what a horn it is! I did a trace comparing polarity of the drivers and found the bass bin/mid horn crossed over region improves with a polarity change. (Mid horn to tweeter took a dip, so I left those as same polarity.) Green trace shows all three drives with same polarity. Red shows what happens with I change the polarity of my bass bin. I'll do some listening for a while and see if I like it.

Anyone tried it on your Eliptrac 400 horn, Dave?

I do recall reading that somewhere. On the ALK Engineering site, no mention of it with regard to the Eliptrac 400 specifically that I could find.

I didn't see it on the US Speaker website, I thought perhaps it was dropped from their line. If I'm mistaken, perhaps someone can correct me.

ALK Engineering had rated the B&C DCM50 driver quite highly as perhaps the ultimate midrange driver. Seems like it is no longer in the B&C lineup. Anyone using it or care to comment?

I took Bob's and ALK's graphs and superimposed them over mine for comparison purposes, scaled correctly. (Hopefully Bob and ALK are okay with this, otherwise, I'll remove it.) All readings are at 1 meter.

Yep, my Dayton EMM-6 mic has a calibration file that is loaded into the software where required. Just to compare, I have an AudioControl Graphic EQ with a spectrum analyzer and a dedicated mic. I also used it to read the Radian, and I get identical results that REW and the Dayton mic show.

I made some new measurements, took out the active crossover, and set the frequency sweep limits to 450Hz~20kHz. Today, I also used a different pre-amp, different power amp, and a different computer. Mic is still 1meter away, I can try to get a close reading later, gotta get back to other tasks. What's the theory of measuring right at the mouth to try to get an even graph, if I still need to do a graphic EQ boost of 10dB at 7680Hz, and 12dB at 15.5Hz for normal listening with this driver? Two graphs posted, 1/3 octave smoothening. The bottom one is just a zoomed-in version of the same sweep.

Won' t sending full range signal to that driver damage it?

Active, tried a TDM and a Furman, both 24dB/Oct

Indoor measurements. I re-read today at 1 meter, dead center. I scaled my chart to match Bob's chart for EZ visual comparison. (Just a little less SPL, I forgot my hearing protection.) Flat, I see a 10dB drop starting after 5kHz. That is the green line. The blue is with graphic EQ boost of 10dB at 7680Hz, and 12dB at 15.5Hz. I haven't heard back from US Speaker yet, I'll call today. Al told me he'd guarantee I'd be satisfied with the drivers, so I may have to take him up on it and look at the Faital.

So why does my response look as such on the high end?

Pink noise with REW software, RTA measurements at 10'. Mic moved all around, this is the most even output. All preamp controls flat, no eq. Do I simply have to boost the bejeebers out of my highs on my preamp? With the impressive smooth graph from Radian of that driver, I thought I could get the same with flat controls. I have no titanium diaphram drivers test against.