Home/Computer Audio

[Chris@VargasTurboTech]

Ha! It's all in the calibration. The analogy isn't quite correct but think of a large turbo with increased boost as RPM raises to target a rising torque curve all the way to redline. You'd need to move a ton of air up top to do so, and you'd leave a ton of potential on the table in the midrange rpm's. That is not completely dissimilar to what I'm doing here. ~60hz or so I'm pulling down 15dB of response to keep it on target down below 20hz, and be able to play at decent volumes down there. Remember, for every octave you drop (halving of frequency), you need 4x the excursion to play at the same sound level, so it's easy to "run out of steam" so to speak if you truly want something that drops very low.

But yes, there is a nice tactile component to being so nearfield. Love it.

Chris

 

[R.G.]

Ha! It's all in the calibration. The analogy isn't quite correct but think of a large turbo with increased boost as RPM raises to target a rising torque curve all the way to redline. You'd need to move a ton of air up top to do so, and you'd leave a ton of potential on the table in the midrange rpm's. That is not completely dissimilar to what I'm doing here. ~60hz or so I'm pulling down 15dB of response to keep it on target down below 20hz, and be able to play at decent volumes down there. Remember, for every octave you drop (halving of frequency), you need 4x the excursion to play at the same sound level, so it's easy to "run out of steam" so to speak if you truly want something that drops very low.

But yes, there is a nice tactile component to being so nearfield. Love it.

Chris

That...is actually a great analogy. Did not know that. I do know 4 JBL 12s will knock some windows out cranked to 11 tho. That is some serious equipment.

 

[fmorelli]

@Chris@VargasTurboTech ... I think you have a problem ...

Filippo

 

[Asbjorn]

@Chris@VargasTurboTech ... I think you have a problem ...

Filippo

You do not have a real problem until you do something like this.

I remember the first time I heard the Dali Megalines, (24 woofers, each 6in or so), and the lack of low end bass was shocking. You either need very large bass units, or a lot of filtering to get a flat response to 20hz in a normal listening room. It is just physics, and not the fault of @Chris@VargasTurboTech

Audio is very religious though. As humans we are good a filtering out noise, but often feel different about different types of distortion, which means we are not objective when evaluating sound quality. Putting in a filter may give you a flatter frequency and time response, but could offer it's own coloring of the sound. Just like different cables, resistors and capacitors sound different to our ears. Personally I typically feel that digital equalizers take away some soul. On top of that our ears are not even linear, meaning that at low sound levels, we can't hear bass as well as we can at higher sound levels. This means if you play at low volumes you are somewhat allowed to turn up the bass a little (activate loudness), but then you need to turn it off again when you turn up the volume...

More than ten years ago, my work was to develop large anechoic chambers and then to attenuate structure borne sound in hearing aids. That's when you pull out all the advanced sound measuring equipment, computer models etc. As for hifi, just realize what you are trying to achieve is an emotion. And even a small bluetooth speaker will offer that. Having access to sound is infinetely better than no access, but the gains from there are minimal. The right company, mood etc then becomes more important. That being said, the hobby of building things, playing with electronics, discussing stuff on forums etc is really fun in and by itself. Just like discussing different turbos is fun, but actually starting to go fast goes from being exciting to downright scary and just strains the neck. Very loud deep bass is not actually enjoyable at all either.

But bass is important. Especially in a car. I can enjoy music without a strong bass almost anywhere but in my car. Not sure why. Maybe its the noise.

 

[Chris@VargasTurboTech]

@Chris@VargasTurboTech ... I think you have a problem ...

Filippo

You don't know the half of it. Still working through the design but the main system will have somewhere between 28 and 36 12's when complete.

...

Yeah that's a lot of surface area but without EQ most 6-1/2's are not going to dig that deep no matter how many of them you have.

Aside: Tangband W6-1139SIF is a really REALLY fun little bugger that is hard to model but goes shockingly deep in the right enclosure. My vote for "most fun" 6.5" without doing anything crazy or super expensive. Good for a normal person computer subwoofer. Ok, maybe two of them. Probably wouldn't use them for anything besides a sub but check 'em out: https://www.parts-express.com/tang-band-w6-1139sif-6-1-2-paper-cone-subwoofer-speaker--264-919

Audio is religious, but there are ways of filtering out a lot of that "stuff" if you have a mind to. I was subjected to the witchcraft side of audio very early in my career and drew strong parallels to my own (overtly) religious upbringing, and knew that while for some people salvation lies there, for me, it didn't. It is absolutely amazing and worth understanding, though, that most of these people believe everything they're saying (and hearing what they think they do), as the human mind is amazingly capable of filling in blanks, focusing on certain aspects of sound, and in general is very susceptible to being fooled. The test engineer in me is not amused, the pragmatist in me says hell, if you think your cables make sound more enjoyable and then you go enjoy your music more... does it harm anyone? Nah.

It was my own blind testing of both my own hearing capability as well as hgh end equipment, along with my increased understanding of ideal frequency responses that lead me away from signal purity/minimalist systems, although I am not so stubborn that I don't enjoy lesser systems (I have a few... and really like the vintage systems... just a different vibe I get).

B&K's 1974 paper "Relevant loudspeaker tests in studios in hi-fi dealer' demo room in the home etc. -using 1/3 octave, pink-weighted, random noise" article lead me down the path to start what would end up being a very firm belief that room eq is all but mandatory in nearly 100% of the rooms I've encountered. I have a pdf if any of you are interested. Hours spent measuring confirms this belief.

Taking that and graduating towards the Harmon Target Curve has been fun and rewarding. Now I'm playing with fairly advanced algorithms to ensure multiple subwoofers play nicely across a variety of seating positions.

 

[fmorelli]

You don't know the half of it. Still working through the design but the main system will have somewhere between 28 and 36 12's when complete.

Of course you recall this ... and it says it all ...

Filippo

 

[Chris@VargasTurboTech]

Next design; dual opposed 12" drivers. I am using a LOT of them, so I'll probably have at least 3-4 of these across the front.

 

[Chris@VargasTurboTech]

Ok, I got hosed on this and suffered delays. Got a new cad guy, have a CNC vendor/supplier I'll be using. About a week out from submitting drawings to them for final quote and if good build test sample.

 

[Chris@VargasTurboTech]

Got the sample finally, and have started the build. I love it when a plan comes together. Tony & Chaz must have spent a billion dollars boxing this up (sample went straight to VTT vs. my house), but UPS got a little damage in still (they don't like 60+ lb boxes, especially around xmas time).

First night I slapped some of it together (just placed, no glue/etc) to see how fitment and dimensions looked. Good. Real good:

So I started putting 'er together. Never go easy on the glue. Brads are just to help hold while glue is drying; they are unnecessary overall, but do help make life easier, right up until you have to cover the brad holes anyway.

She's going to be stout, no two ways about it. Material was spec'd as 20mm, actual was a hair over. It's not cheap, weak, or light.

Put a couple of dustcapped JBL's in raw just to see how it would look. I'm very happy, to me this is by far the most aesthetically pleasing design I've done to date. I love the deep recess driver look with the 12mm roundover. Has a super clean look IMO.

You could but a veneer on the sides and duratex the front/rear, but I'm just going to duratex the whole thing. It's easy, durable, non-toxic and reasonably priced -plus blends in to most decors. There will be MANY more of these to come so lets not get too crazy with finishing.

Finishing starts with filling brad holes, sanding, and fixing any issues (like the corners UPS wrecked but I fixed). Usually I use drywall compound but decided to use epoxy instead this time. I'm undecided; it's better for sure long term but what a PITA compared to slapping on some quick compound and being done. Some say the spackle will eventually pop out but I've never experienced that; I'm sure this epoxy is permanent though.

You can see one chunk missing on the top right(ish) part of this photo (lots of epoxy).

Some patience and all is forgotten. This is the bottom, and taken same angle showing the repaired damage; you can't see it. This is with 2 coats of Duratex, I usually do ~4.

More to come soon including testing!

Chris

 

[doublespaces]

Let me know when it's working. After about 10 invitations perhaps I'll be able to make some time.

 

[Chris@VargasTurboTech]

Sample is together and working. It performs as per design -no surprises there. Now to make many more.

 

[doublespaces]

So, it's 'just a speaker' right?

 

[Chris@VargasTurboTech]

Just a sub. One that needs some DSP. It sounds good, dialed in. I just have the car tuning equivalent of a base map on it, ran a quick linkwitz transform to drop q to 0.5 and F3 to 25hz (position is horrible) then pulled down 60hz range a few dB. Upper bass is effortless, then it just keeps digging. Bass guitar/upright bass sounds real.

Deciding on number of brothers for this. Prob 10.

Edit: if you want one let me know soon. Cost is about $200 (little under) to AZ (box only, flat pack, unassembled).

 

[Chris@VargasTurboTech]

Buddy of mine is opening a bar in PHX. Sold all the subs to him as his audio plans fell through. I am currently mostly subless. It is a sad, dark place to be.

 

[Chris@VargasTurboTech]

Insert record screeching sound. All stop! Plan change.

For no good reason decided to do something different for the main system. Going big, and high efficiency. LaVoce San 214.50 21" drivers next to a 12" JBL and the 11.5 lb Walter. Will likely do dual 21" ported cabinets, might do passive radiator if my sources can find/steal/make one big enough.

 

[doublespaces]

What is the reason for changing it up?

 

[Chris@VargasTurboTech]

What is the reason for changing it up?

No real reason other than I reached the goal. After this virus stuff lets us back to life, you can hear them downtown at "Killer Whale Sex Club" on Roosevelt & 6th St. I wanted to do something a little more challenging. The 21's have a HUGE motor, being 20x stronger than the JBL. Even accounting for displacement differences, it's still monstrous. I'm getting custom made passive radiators to do some testing. Kind of going the other direction... these will be BIG, very efficient, and move enough air for commercial usage.

Something different. Keep the thrill of the chase going.

Chris

 

[fmorelli]

Ok ... just stroking a bad habit. I've been thinking I'd like a legit solid state stereo amp. My mine stereo amp is a KT88 tubed Dynaco-based amplifier I built a few years ago. So I got wrapped up around a guy named John Curl who is a bit of a design genius. Got a hold of one of his older amps, which had an issue, so it came cheap. A bunch of diag, lots of upgrades, and finally sorted it out. Sounds great after a half-dozen hours of breaking in. Was about 4 weeks of work, and as usual, learned a few lessons along the way.

Filippo

Photos: https://photos.app.goo.gl/hy9a4Mfdmgm2ey979

Build Sheet:

 

[Chris@VargasTurboTech]

Good stuff! You spent some effort bringing 'er back!

I used to have a 1500A, bought one used with every last penny I had when in college, sold it to a friend, it had some solder around the terminals need to be re-flowed (which was done at Parasound) but still running good for my buddy. I always liked Parasound, I still use a ZPre2 as a pre-amp on the computer system. Amp wise, I've personally switched to using all Crown amps, but my power needs exceed the norm.

Chris

 

[fmorelli]

Nice. John Curl is an amplifier design wizard.

This was actually preparatory work for the amp I'm going to do next which will be my permanent solid state amp. It's an HCA-3500 which is basically a dual monoblock in a stereo chassis, weighing 100 lbs. Massive torrodial transformers.

It's fun stuff. My version of stress relief

Filippo