What I am looking for it a speaker that has high output capability with low distortion, fully capable of being able to reproduce cleanly the sound pressure levels in my home theater room typical of THX-reference levels and rock performances. However, at the same time it must be able to reproduce the individual strings of a 12 string guitar at low sound pressure levels.
Final Design with components:
Front baffle [modeled after the JBL 4345 Studio Monitor]:
Design is tri-amped, with a active LF and MF combined with passive HF [7 Pi XO for the compression driver] due to gain structure of the DSP unit (Peavey VSX 26)
Ordered the Midhorn flatpacks and Eminence Delta 10A drivers from Pi Speakers this afternoon, which marked the end of the design phase and thus a new - and final - thread. I need to build the midhorns to finalize the bracing scheme, but the overall net volume of the cabinet will mimic the JBL 4345, with the same 32 Hz tuning. Desire is for full range performance for music, which will be around 70% of the speakers utilization.
Great to see a thread starting on this build. Hopefully your build will be done before mine. I have had two ideas rolling around for a while. One idea was a very similar idea 3 way and the other was the two way. If things go well I will do the three way. BUT for now I really want to see how you like your setup.
These will be rather large enclosures, any mistakes will thus me magnified. I am thinking of building an aluminum frame (8020 material) to assist with keeping the enclosures square during the gluing process.
@Scott Simonian
scott's successful implementation of the midhorn was probably the major influence, no?
i was all over the map and half the time repeating things you said six months ago, lol.
hopefully you will drop wayne a note to let him know what you are up to (if you haven't already). i'm sure he would think your plan is pretty cool.
still like the blue baffles.
Yeah Scott is guilty as charged! I have been emailing Wayne on the project, I know he would prefer the straight 7 Pi build as its his favorite speaker.
Depends on the shape of the driver roll-off. Wayne paired the XO with the natural roll-off ala JBL, so with the "quasi" first order design the actual acoustical roll-off is much greater than the simple 6 dB/octave.
For the LF I doubt I can go this way as I am using a larger enclosure and different driver. Will measure and lusten to determine the best approach for me. I know the forth order Linkwitz-Riley, having fixed slopes, 24dB/octave (Q 0.5) and -6dB at crossover point (Bessel), has been adopted as the standard for professional systems as the steep slopes give maximum protection, control and power capability for the drivers.
With my electronic crossover I have the flexibility to try, and measure, various filter options. What I've read in multiple places is that 2nd order 12dB/octave crossovers attenuate the music without hearing a tone or color change in midrange speaker crossed over in isolation (but does that translate to a complete system). Higher order crossovers attenuate the music causing a subtle but noticeable tone or color change (but will I pick them up).
I am not a crossover guru, so the project will probably meander for awhile until I find what I like best at that moment in time.
"I am not a crossover guru, so the project will probably meander for awhile..."
i suspect what alpha niner was referring to, in part, is the 2242 has a rising response well into the lower midrange (and on top of that there is baffle step transition). so even with a 6db/oct low pass at 250hz, you might not even end up being down 6db by 1khz (or more) on the woofer section. might want to start with 4th order acoustic slopes and experiment from there. at least that gets phase pretty much in line and limits each subsystem to its intended pass band, but hey...its a free country.
Yeah, the 2242 does have a pretty hearty rising response starting at 800 Hz. If not adequately attenuated it would really muddy the midrange. I have no issues with going with the 4th order on the lf.
No doubt I know a lot less than @A9X-308 on this topic and am always willing to learn.
Yeah, the 2242 does have a pretty hearty rising response starting at 800 Hz. If not adequately attenuated it would really muddy the midrange. I have no issues with going with the 4th order on the lf.
No doubt I know a lot less than @A9X-308 on this topic and am always willing to learn.
In one of my early designs, I used a KEF B139 for bass with a 12dB slope to the mid at 300Hz or so. For ages there was a mid anomaly I and a friend could hear occasionally, but didn't show in the measured response*. It turned out the B139 had a sharp resonance over 1kHz. I built a notch for it and the problem was gone. Be very aware that out of band artifacts can turn out to be very audible with shallow slopes even if you think they're far enough out of band to be inaudible.
Another tip would be to not just focus on the FR, but other aspects such as distortion as well. Most drivers start to increase in THD at the lower end of their operating BW, but many do at the top as well. Just because the FR and acoustic slope on a midrange look good at 200Hz, doesn't mean that it won't perform better with a 300Hz xover because of something else like THD or maybe with a steeper slope. Just because the mid on your horn is going to give a nice roll off because it's in a small sealed enclosure, doesn't mean that it won't be better rolled off steeply. With a 200Hz 1st order you'll still be feeding it a significant amount of power below this and if the driver does increase in THD, the components produced will be in the active BW of the driver/flare and likely audible.
Before I moved back to Sydney, I had a very large 5 way front loaded horn system. It had been 3 years work and set up with as little xover as possible (it was powered by a monster own design tube amp**). Sounded great. But then I got the offer to try some new DSP xovers. On a whim, I decided to go the other way and try 8th order slopes. So with levels set I started to listen. It was one of the few jaw dropping experiences in audio for me.
In your response to my first post, you mentioned you'd read about what different slopes sound like: In my own experience, that's malarky. How many of those people have measured many aspects of the system to see what really caused the audible difference? In my experience of the DIY world, very few. They just change the slope and declare the result.
* This was on an analog CRO with custom logarithmic amplifiers. And no capture.
** For those who've read my comments on tube amps here over the years, I did it because it was fun to design and build. It had a lot of SS in it, so purists hated it. It was also the size of a three drawer filing cabinet and for 50W class A, drew >1kW from the wall at idle. I used an SS amp at least as often and was no less satisfied.
On a very related note, I had recently had to re-do all my crossover settings for my mains. Made one change that really seemed to clean up the midrange. I went from a 24dB L-R to a 48dB L-R on the lowpass for the midrange. I was amazed how much clearer it sounded. Made no difference in the measured (total) response at all but it was audible. (it was measurable when isolated to just the midrange playing)
Anyway...this was a specific instance but it backs up with Alpha Niner is talking about. Already was recommending some steeper slopes than you planned for but also assuring that you need to listen while designing your own speakers. Don't just let some internet papers make your project for you. It becomes yours while you make it.
Completely different environment but I too found 48dB as my preferred slope when running my active 3 way, it actually was my preferred all the way around, but I did often switch to 24dB/oct. to confirm my own personal findings. Didn't have REW back then to fact-check myself tho....
Thanks for the great input guys. I currently have the 2242's in the C4645B cabinet, which I believe fits the suggestion (I am assuming you are refering to a system built to utilize a +6 dB filter at resonance as a B6 alignment) and they sound great. With the enclosure being so big I can replicate the running of the 4645B.
Will track distortion on my REW measurements, not sure if a different software would do a better job. I am decent with REW so will probably stick with it.
I was thinking of putting a notch filter on the nasty 1.2 kHz peak on the 2242 if I have a free PEQ band after all the settings. I plan to replace the Peavey AVX with a dbx Venu360 next year which has a lot more powerful DSP engine.
A9X, I bolded the parts on slope above as I agree with you that the audible differences I read about may be over-stated. I trust your experience, and my own ears when the time comes, more than reading engineering stuff of the Internet (from Australia, http://education.lenardaudio.com/en/06_x-over_3.html, among other sources). I have published more than 20 peer reviewed scientific manuscripts and in the process I have learned how to turn a pigs ear into a silk purse.
I am so happy with gaining valuable input on this build. I am just about 52, this will likely be my last big speaker build. If I need to upgrade in 10 yrs or so I will probably just open up the check book and buy some studio monitors from one of the serious design teams (JBL, Meyer Sound, Adam, etc).
If I need to upgrade in 10 yrs or so I will probably just open up the check book and buy some studio monitors from one of the serious design teams (JBL, Meyer Sound, Adam, etc).
Any recommendations on enclosure material? The plan is 13-ply 18 mm Baltic Birch, but I was thinking about adding a 0.5" layer of MDF to the sides and rear of the enclosure. I know JBL used 1" particle board for their monitor enclosures, so I am wondering if 1.2" thickness would be better than 0.709" thickness. I hate MDF, but would be willing to use it inside the enclosure.
the steep slopes are interesting as they reduce the passband of each driver which has benefits as many have mentioned. the downside is the additional phase roll. supposedly that is only audible under very controlled (contrived?) scenarios with headphones and test tones, but i can't help but wonder if all that phase messes up something in our brains. just seems too easy to slap very steep slopes in between the drivers and call it a day. except for the linear phase corrected examples, i can't really think off hand of anybody who does it this way. just thinking out loud....
Thanks, it does seem logical to not use FIR filters with low frequency due to the number of taps required (and resultant delay as you indicated). Delay on sports would not be cool.
Spending all week at a programmatic review of future medical systems to enhance warfighter performance. Lots of talk about the development, testing and validation of in silico testbeds to aid with development and FDA clearance. All I could think of was to use this build as an "in plywoodo testbed" to test multiple DSP solutions to loudspeaker control. Yep, I have gone loco.
Spending all week at a programmatic review of future medical systems to enhance warfighter performance. Lots of talk about the development, testing and validation of in silico testbeds to aid with development and FDA clearance.
Don't forget to test it in 115F heat, pump in baby powder into the room and vary the voltage from 70V to 150V to make sure it actually works this time. Yeah, I know how well the EMEDS system worked...
Do you plan on putting wheels on the back of the speaker boxes so they can be easily moved when need be? I'm about the same age as you and put handles on my 100+ pound speakers
and subs--because I'm not getting younger and know the garage stuff will move eventually. Good luck!
^
Spending all week at a programmatic review of future medical systems to enhance warfighter performance. Lots of talk about the development, testing and validation of in silico testbeds to aid with development and FDA clearance. All I could think of was to use this build as an "in plywoodo testbed" to test multiple DSP solutions to loudspeaker control. Yep, I have gone loco.
WOW - just reading that almost made me want to take a nap - retirement does have some soothing options,
my vote is for the "in plywoodo testbed".
I wish I was retirement eligible! Two more years till 20, then 2 more to retire at final rank. No telling where I will be headed next, hopefully somewhere where I would like to retire.
I had been planning to use HF dollies for Max v3 but your woodcraft wheels idea, at least on the rear of the cabinet for moving, for me especially from the outside and around to the back of the house
won't go thru the front door . .
>sounds really smart .
They are only on the wheels when they are engaged, they have a rubber bumper which contacts the floor (adjustable) for stability. Built for large, heavy power tools (600 lb rating).
Steve check for a refurb deal. They run them from time to time, I'd imagine probably the cordless is next. I got track, systainer, festool carbide blade, accessories, and saw for I believe $332 shipped. It was best deal IMO, it was obviously brand new and not even a scratch on it. I've cut literally hundreds of sheets of mdf and ply and it's been so rock solid and awesome. I just installed a Frued industrial blade, the festool stock blade lasted me 3 years and hundreds of sheets. I ripped microlam LVL beams (1.5" thick) which is heavy duty ply without any fuss. I also ripped up 1.5" mdf (trupan ultralite) without trouble. Dust collection is so amazing you could cut mdf on the kitchen table and wife won't care. It's quiet too. A portable vac is all you need. For doing DIY sub and speakers and for someone who can't afford or want to store a proper table saw its a great solution. Makita and Dewalt make a nice one, not quite as good but with the sales they run about half price as an alternative. And if you really tight on budget Grizzly has a smaller one for only $99! I thin it's a 5" blade but enough for sheet goods under 1" thick.
Steve check for a refurb deal. They run them from time to time, I'd imagine probably the cordless is next. I got track, systainer, festool carbide blade, accessories, and saw for I believe $332 shipped. It was best deal IMO, it was obviously brand new and not even a scratch on it.
Hmmm...will have to give this little bugger a look.
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