Classix 2.5 is here! Finally!

posted Mar 7, 2017, 8:29 PM by undefinition1   [ updated Mar 7, 2017, 8:29 PM ]

I've been sitting on this one for too long.  Forgive me, it's been a long winter with family and work obligations coming first.  But without further adieu, I am so glad to bring you the Classix 2.5.  It's a 2.5-way TMM tower version of the Classix II.  It's ready to rock out, are you?

Also, I don't have a good photo of it--mine are unfinished and covered in mail :-P  But they're singing some prog rock as we speak!  Hopefully someone soon will build a nice looking pair and I can feature those instead.  

Reddit AMA - Wednesday, February 8 @ 4:00 pm

posted Feb 5, 2017, 9:09 PM by undefinition1   [ updated Feb 6, 2017, 7:28 AM ]

I was invited to do a Reddit AMA this coming Wednesday, February 8 @ 4 pm for the /r/diysound board. (https://www.reddit.com/r/diysound/)  Submit some questions!  Ask Me Anything!  (per the AMA rules, they can be about anything, for better or worse)

Tarkus updates

posted Jan 4, 2017, 9:40 PM by undefinition1

Here we go again.  Just as the crossover for the Amigas was adjusted slightly to accomodate the newer version of the DX25, I had to do the same for the Tarkus.  If you are unsure which version you have, the old tweeter was called DX25TG09-04, and the new one is DX25TG59-04.  

Basically, the only thing that changed was resistor R2.  If you happened to use the old crossover with the new tweeter you may notice the treble is  a bit hot.  This is completely fixable.  You have a few options, all of them pretty easy.  You can either A) replace R2 with a 4 Ohm resistor and be done, or B) you can parallel another 8 Ohm resistor to it to achieve a net 4 Ohm load (remember: 8 Ohm + 8 Ohm = 4 Ohm).  At the very worst case scenario that you cannot reach the crossover board, you can still get the results in solution B by simply soldering the resistor across the + and - leads on the tweeter.

Again, I apologize for the confusion.  This will hopefully be the last retroactive parts update I'll have to do in... well, hopefully ever.

Amiga DX25 tweeter update

posted Sep 9, 2016, 1:34 PM by undefinition1   [ updated Sep 9, 2016, 1:39 PM ]

In the years since I originally published the Amiga, Vifa/Peerless/Tymphany/whatever you want to call them has changed suppliers of the dome material of the DX25.  In doing so, they also changed the model number from DX25TG09-04 to DX25TG59-04.  I have been asked countless times if the newer version was compatible with the existing crossover, but I didn't have any of the new tweeters on-hand to measure so I winged it as best I could from mfr. spec sheets.  I finally got a pair of the new "59" models to measure in the design, and the good news is that it's very close.  The bad news is that you might want to swap out a resistor in the crossover to compensate, if you built the old XO with the new tweeter.  From the Amiga page:

It turns out that the spec sheets are precisely true, and the new ("59") tweeters are 2 dB hotter than the originals ("09").  Will they drop into the original crossover?  Yes.  Will the treble be a bit bright?  To some ears, yes it might.  There is a fix, though, and it's super-easy.  Simply swap resistor R2 (4.7 Ohms in the original crossover) for the updated value of 2.4 Ohms.  (Or, if for some reason you cannot access and/or modify the crossover, you can accomplish the same result electronically by putting another 4.7 Ohm resistor across the + and - leads of the tweeter--essentially creating a parallel resistor pair with a total of 2.35 Ohms)

So, to clarify, if your tweeter is labeled DX25TG09-04, use this old crossover.
If your tweeter is labeled DX25TG59-04, use the new, updated crossover below

I apologize profusely if I have inconvenienced anyone with this.  This is only a hobby for me, and as we've seen in the past, I can't always keep up with manufacturers changing things.  I have notified Parts Express and they are aware of the issue as well.  If you are ordering the Amiga kit from Parts Express and have any concerns, please feel free to call them; their customer service is excellent.

Updating build photos

posted Nov 27, 2015, 2:17 PM by undefinition1

I've said it many times, and I'll say it again.  The level of skill and creativity I see from people's builds of my designs never fails to blow me away.  I've been super-behind on updating a lot of pages, though.  Well, today I finally took some time to update some inspiring builds of the Tarkus, Sprite, Classix II, and even the Tubifex.  If you have an interesting one I haven't seen, feel free to email it to me.  I don't follow every audio board, so there may be some really amazing builds I've never seen.  

I, for one, welcome our new DSP overlords

posted Sep 1, 2015, 9:14 PM by undefinition1   [ updated Sep 2, 2015, 6:56 AM ]

I did something the other day that I honestly thought I'd never do again: I bought a commercial speaker.  

Here was the story.  At my current office, the noise level needs to be down pretty quiet.  Something like the Speedster--which I gladly rocked daily at my last job--would have been overkill.  So I was stuck with either crappy Dell USB-powered computer speakers, or an even crappier "soundbar" attached to the bottom of my monitor.  Either way, I was getting crap.  I lusted for bass, maybe just a hint of bass... even a low midrange.  I needed some real speakers, badly!

I went to my stash(es) in search of small drivers that could make a tiny computer speaker.  However, I ran into the same problem I've written about in the past: it seems that--regardless of the driver--in an enclosure smaller than 4 Liters, I just can't get satisfactory bass.  Basically, nothing below 100 Hz, and usually a large hump around 150 Hz.  And that ain't bass.  In fact, if anything I'd rather have no bass than have that annoying 150 Hz boxy "punch."  

Am I banging against the limits of the laws of physics and acoustics?  Perhaps.  But there is a digital solution: EQ.  That's right, with the slide of a fader, I can suck that 150 Hz bump into oblivion.  And while I'm at it, why not boost around 60 Hz?  Is this sort of frequency shaping any different than what Linkwitz does with his brilliant designs?  Using EQ placed before the amplification stage can make good economic sense.  It saves one not just money on passive crossover components, but also on lost energy being thrown away as heat through large coils and resistors.  

Maybe EQ is too garish of a word; let's say "Digital Signal Processing" instead.  So what can DSP do for us designers?  Um, with the cheapness of computers and microprocessors these days, pretty much anything we can dream up--once someone comes up with an turnkey solution for DIYers to implement.  In my opinion, as neat as MiniDSP and Ultimate Equalizer are, there's still too much setup, and too much ancillary equipment needed for there to be a mass appeal.  

Thus, most of the good DSP toys are still in the hands of the manufacturers.  I went over to Best Buy to take a listen to what kinds of DSP magic was currently available on the consumer market.  Specifically, the little Bluetooth speakers.  There were definitely some interesting performers breaking the size/performance barrier, but one stood out heads and shoulders above the rest: the unassuming Sony SRS-X33.  Here was a device about the size of a pound of butter that was putting out REAL bass down to 60 Hz.  Not fake bass; not harmonics.  Of course, without DSP, this would not even be possible.  In addition to that, seeing some measurements of the speaker shows that Sony's engineers put a lot of effort into shaping the overall response to make a great-sounding speaker, not just something to play background music or have a cheap party.  The Sony's FR is in Blue in that link.  Notice the big fat dip around 150 Hz.  Coincidence?  I think not!  (Not my measurements, but a good article.  Full link here)

And at $100, really the Sony SRS-X33 is not that bad of a deal.  It's actually on the low end of what are considered "good sounding" Bluetooth speakers--not that that metric has much of any meaning to me.  So to put it into terms I could understand in order to justify the purchase: it's the same price as a pair of Dayton RS180, or about 1/2 the price as one 5" Scan-Speak Revelator woofer.  

You know you're a 21st century tool when...

posted Sep 17, 2014, 9:01 PM by undefinition1

... you have a Twitter account


I promise to keep it entertaining, and mostly DIY and music-related.  Plus, I don't take pictures of my food!

HiVi L6-4R

posted Aug 18, 2014, 9:23 PM by undefinition1   [ updated Aug 18, 2014, 10:49 PM ]

This driver is awesome. We should all be sent to bed without dessert for not using it sooner.
  • First of all, it just looks cool as hell.  A woven black Kevlar cone PLUS black phase plug?  It's like a stealth fighter and bulletproof vest and Bugatti Veyron all at the same time!  It is all that is man.
  • Second, the Frequency Response is very well-behaved.  DIYers have lost the easy-to-work-with woofers like the Vifa P-series and Audax over the years, in favor of aluminum and inventive combinations of paper.  The L6-4R behaves more like a classic poly cone, and is therefore super easy to work with.  Just look at it.  It's beautiful!  No need for high-order filters here.  Lots of room for experimentation, and it's not going to hiss at you like a metal cone if you screw it up. 

  • Third, it's a high sensitivity driver.  Now yes, this is a result of it being a "4 Ohm" woofer.  But so what?  Who among the DIY addicted doesn't have a large collection of amplifiers, and at least some of which can drive 4 Ohm loads?  Plus, once the L6-4R is combined with the series resistance of a decent lowpass filter, the actual impedance minima would be closer to 5 Ohms (and there's a good number of commercially available "8 Ohms nominal" speakers out there that pull that trick).  So many of us are used to using "8 Ohm" woofers in bookshelf speakers, getting used to sensitivities around 82 - 83 dB that we forget what it's like to have a mere bookshelf speaker bark at us with the volume knob barely turned up. 
  • And unlike an "8 Ohm" high sensitivity woofer, its bass does not suck.  In fact, the bass is pretty darn good.  I have it in a .5 cu ft bookshelf speaker, and it can do rap and metal just fine.  About the only thing you'd need a sub for is LFE in movies.

I threw together a bookshelf speaker using this woofer and the controversial Airborne RT-4001.  I call it the Spitfire.  It's a blast to listen to.  They sound really big, and that smooth FR from the woofer means no listening fatigue.  If I can make it to a DIY event in the near future, I'll bring it with so people can hear the good news. 


The box is vented, and has a 2" dia x 4" vent on the backside behind the tweeter.  This tunes it to approximately 54 Hz.

But really the purpose of this post is not to publish another design.  If you like the Spitfire, great; if not, move on.  What I'm here to say is that the HiVi L6-4R is an awesome woofer, and the DIY community has been missing out by not putting it to good use!

The Carrera

posted Mar 23, 2014, 7:35 PM by undefinition1

Finally, after 3 years, I can bring this design on back home.  I'm very glad to present the Carrera.

On a sad note

posted Mar 23, 2014, 7:30 PM by undefinition1

The DIY community recently lost a very valuable, beloved member this week.  Lou Corragio has been there for just about all of us in the hobby (myself included), with sound DIY advice, a kind heart, and a heaping helping of dry wit.  His presence will be sorely missed.  The upside is that he left us so much good reading material.  I know many DIYers have downloaded his entire site this week.  I have a hard time visiting it right now, though, because it makes me so sad.

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