A little project

[Greebe]

Nobody has posted in here in two years sooooooooo...

During the years following my sons health issues abandoned all of my speaker design desires. Doctors worried that the bass ala boom boom can induce seizures. A few years ago got back into what I had missed in the 20 year absence. Rediscovering what I forgot, what has changed, and or further knowledge of what has been researched since then. This all started as a small speaker project for my son whom absolutely loves music. No risk of seizures anymore. Well my life has it's ups and downs, mostly the latter and that project never saw the light of day, despite being rather cheap for a DIY speaker project. I did set him up a small FAST system, HK receiver cheap (ebay), a Samsung tablet loaded with a mess of FLAC files, Monsoon active sub from my PC, and a couple of small modified KLH satellite speakers pulled from next to a dumpster, cheap, sounds great. It is far more capable than what he needs in a bedroom. He's a very happy camper as long as it's not on the radio. Well FM isn't the problem, it's the commercials, he HATES them and gets rather disgruntled and loud when they are on. Hence the Tablet, music all day/night without any of that. Now if I could figure out just WHY IN THE WORLD he likes to listen to P!NK all day! LOL ...he also likes Bob Segar, The CARS, Katy Perry, Billy Squire, Def Leopard and Van Halen (pretty much in that order)

Well with that dissolved (resolved?) decided it has been far too long with myself wanting something along those lines, yet a bit more capable (understatement of the year). Decided on a transmission line design of my own making, after pouring through everything I can find on the subject made one using the same inexpensive 6.5" woofer (in quantity <$20 ea). Well this project has been languishing for some time due to lack of funds, but I found something critical that was missed in the theory of how they function. Will not go into that as I am hoping to get a patent.

With that said, have built a three way utilizing the TL sub mated with a push pull planar fullrange and topped it off with an AMT Tweeter.
System is Active utilizing a miniDSP 2x4 with a 4 way plugin software control. Crossover points at 330Hz and 3300Hz. It has a frequency range of 26 ->20kHz. The AMT is capable of 30kHz plus, but is limited by the active crossover which stops at 24kHz when set to operate at 48kHz sampling rate. Analysis shows inaudible distortion pretty much across it's operating range. I am so tickled can't hold it anymore.

Everything is time aligned and or compensated via active crossover so even horizontal polar response is spot on. OMG I need cash to finish, had hoped Santa would be good to me, but it's not going to happen anytime soon. Damn it's eating at me bad. Have to finish the power supplies which use two 625va Toroid transformers. Have had these for some time, but the rest, ala softstart, filter caps et al are still needed. It's funny these transformers operate from either 120 or 230 vac 50/60Hz so pretty universal and only draw about 7amps each full tilt, but powering them up is hell as they pull 26amps each easily popping a 15amp CKT Breaker. Even at that if there is a minor power blip that exceeds 50msec the internal field collapses and pop goes the breaker. I designed a softstart ckt to resolve that, and it doesn't cost that much. Well the PS's themselves do cost considerably, around $400 total for two. These power two four channel power amps rated at 100w/ch x 8 channels @ 4ohms. The Amps are being derated by 50% or half power. They are actually capable of 2000w total into a 2ohm load, but the spec also puts that into the 10% distortion category, simply not going to happen, not in a high end design like this. So derating is in, fidelity is maintained and distortion is kept in check. As an added benefit they'll last longer and run cooler, without the need for fans to muck things up.

Actually one of the problems I have is that they actually work too well in the first two octave range. My testing lab, which is a small room on the back of the house would never require speakers like these, EQing them flat in here is the same as not having a sub at all, no need for it. Of course there is a door to the back yard and a deck where I do outdoor testing, where they still sound too intense in the first octave! On Veterans Day had all this mess setup outside and played Dire Straights, Brothers in Arms full blast. Had neighbors come over to hear what I was up to. Have to honor my brothers on this special day.

Oh back to that no need in this small room, DAMN Dubstep and Dance music is clean, articulate and powerful... from one little 6.5". An impressive task considering it'll play symphonic music with aplomb. A Cello sounds real, most speakers can't come close. Can only power One speaker full power or two at 1/3rd power atm. Which rather sucks, need power supplies dang it.
The full production design calls for 8 of these woofers and am considering dialing that back to just 2 per speaker, for a total of 4. I have a dozen of these woofers at my disposal.

I want my Patent more than anything, but also want to prove my theory is correct above all else. Don't need the theory for the patent, but do have peers I highly respect and for that respect to be reflected back to me is the reason to prove the theory. One of these peers now heads the engineering dept for Bose corporation as a replacement to Dr. Amar Bose whom passed three years ago.

[Umfriend]

Interesting. I am wondering, the 24KHz boundary, is that pure sinus or can it do, say, 22KHz sawtooth well as well? And derating is interesting,feels a bit like underclocking/undervolting a CPU to get better performance properties (in my case, heat & fan noise which are more important than pure performance above a certan threshold).

[Greebe]

Due to the extreme elliptical filtering at the very top of the range ringing occurs. It's a sinus type and is like a resonance that is triggered by any signal stepping into that range. Clean to 22kHz but sharply rises above that. seeing that nothing professionally recorded has any content above 20kHz there is no problems. If an old analogue signal is converted which contains information above the standard limit it will cause ringing. So special care is taken to prevent this from happening with a strong filter limit. BTW studio's typically encode at a 48kHz sampling rate, all mixing effects et al are done at this rate and then down sampled to 44.1 kHz for consumer products. This is true for all audio D/A converters. You cannot hear it as it's typically out of the range of most, like on the order of 99.9% but not all people. I know a few women that can hear above 25kHz. Had my hearing retested, I can still hear well above the norm for my age which typically tops out at 12kHz, can still hear to 20kHz. They couldn't go above this frequency limit.

I run my setup typically at 24kHz (48kHz sampling rate), but at times do run them at 22,050 Hz(22k). The latter is when sampled at the standard 44.1kHz most every audio CD is encoded at. In this case the ringing still occurs , but is kept above 20kHz limit imposed by Sony when they invented CD's back in the 'early '80's. The reason for the switch at times is do to aliasing where information is lost do to the difference between 48kHz and 44.1kHz sampling rates. (I could re right that better but hope you'll understand the gist of it)

Derating an amplifier is common practice in pro audio. For example, when I maintained the sound system at the Charlotte (North Carolina) Coliseum we had rows upon rows of racks of Yamaha P2250 and P2150 power amplifiers. The last three digits indicates power per channel and are run at a max of -3dB power via 70v line transformers. This is the half power point or more specifically 125w and 75w respectively.

BTW a friend of mine lives in the Netherlands and has designed a line array that is said to be uneffingbelievable, best sounding speakers anyone has ever heard. Helped push him to complete his project as it was a grueling task. The Making of: The Two Towers

a very long and technically complete thread. WESAYSO aka Ronald is a very nice guy. If you were to contact him most likely he would have you swing by for a listen

[Umfriend]

I assume the main gaol of derating is to avoid clipping?

I thought studio's produced at 96 or 192KHz. I guess you don;t feel DSD has added value over a 44Khz encoded CD/WAV signal?

Anyway, it has been quite a while since I cared about audio hardware. As I mostly listen to popular music, the biggest problem by far lies in the abhorrent production by the producer and I simply do not have many different mixes/performances of, say, Tommy to choose from.

[Greebe]

I'm more referring to what we get on a CD. Sure the big studio's can hit those sampling rates, but not the smaller ones that abound. @ 20k you get two bits resolution, the ear cannot tell... a BAT, a CAT and a SQUIRREL can I say. BTW, I use 48kHz for measurements just for the higher resolution.

For that to happen you have to focus on expanding your Tommy collection.

When I was in the USAF the first break, a two and a half year long wait, a vacation! My roommate decided to rearrange the dorm room. Put all my albums up against the steam heat radiator and melted all but 30. Thousands $$$ were lost.

[Umfriend]

For that to happen you have to focus on expanding your Tommy collection.

LOL. I actually havehad two. The "remasterd" version in CD and the Deluxe version which has both DSD and CD encoding. I was amazed at what DSD brought. Then I found it was rather hard to hear the difference between the Deluxe CD and DSD encoding so I dug a bit deeper. Found out that the Deluxe edition was based on the original master tapes, not a remasted tape and that made the biggest difference by far.

Unfortunately, I lost the DSD.... frack!

I do have a little (very little) bit of classical music and there there is an abundance of recordings/performances of many pieces. I found that much more than the hardware, good sound is made by the software, i.e., the performance and editing/mixing/producing. A good example of it going wrong is Walking Into Clarksdale. Great music completely ruined in production. When I finally understood that, I basically got less interested in hardware.

[Greebe]

Please check out Chesky Records. How it was recorded is at the pinnacle without all the post production garbage. I use these to rate my designs, critical listening tests et al.

There are others but that one in and of itself is the best starting point.

FRACK is right. You already paid for the right to have the DSD, so go DL it, torrent please The RIAA has never addressed this issue. How many times do I have to pay for the right to listen when every time I have to replace a old/bad/broken media (record, cassette, cd etc) and repeatedly forced to pay this licensing fee? That adds up to some serious $$$ that should not have to be repaid when it's a one time fee.

A friend of mine has an acoustic guitar version of The Killers "Mr. Briteside" that is totally better without all the compression. Have heard them play live on The Tonight Show, Jimmy Fallon that was better than any of the Album versions.

2017 is looking at becoming a new way of life for me. Won't be hindered by unemployment due to caring for my son 24/7/365 x 21+ years now. It was a tough road to walk. Watching everyone else get on with their lives while the world revolves and your standing in place, no change, stagnant. I am quite pleased to see how much we all have grown. Some of you guys are my son's age, so to see (read) the progress that has been made makes me hopeful and quite happy. Hope I was helpful (altho a real PITA at times . With that said many things will change and I will finally be able to act on what I think, say, do and want.