Etude - Super Budget 8" 2-way

[tom_s]

I thought I should finally post my Etude design from Iowa DIY for anyone who might be interested. An Etude is a musical composition written for the purpose of improving ones technique. The name is quite fitting, this being my first true solo design.


I used the 8" MCM 55-2185 DVC aluminum woofer. After the North D25 went NLA, I ended up choosing the Vifa NE19VTS in an effort to keep my costs under $150. This was designed and built to meet a price-point, the former Super Budget class, so this pairing of drivers is not ideal, but it works. I'm really pushing the NE19 to it's limits, crossing over so low, but I don't listen that loud here at home. And it never got ugly or made any disgusting noises (that I heard) in the gazillion cubic foot theater at Grinnell. I'm fairly certain one of the shortcomings of this design is less than perfect power response.

So here's the modeled crossover -

[johnnyrichards]

There wasn't a dog in that room, but I was more impressed the farther down we went in cost. The expensive designs were all beautiful - but also very illustrative of the diminishing returns theory on loudspeaker design.

I thoroughly enjoyed listening to these, Tom. I did pick up on a hint of brightness, but that could very well have been my listening position, and breakups are not always as well behaved off-axis as they are on.

You did a fine job, and the MCM woofer I think was a surprise to everyone. Good work, sir.

[arlis_1957@yahoo.com]

i agree. really cheated myself not geting closer to the middle. the still sounded good.

[tom_s]

Thanks guys! I do sometimes hear something that sounds a tad aggressive...and my nasty, untreated room isn't helping that situation!

[tom_s]

Here's more info for interested parties-

Voice coils on the woofer are in parallel and you can see the electrical impedance in the previous post. I centered the tweeters since I have them pointing straight ahead in my room. My listening distance is only 9 feet, so I'm a bit off-axis and baffle induced ripple should be lower than if they were toed in. Plus it looks better - admit it, looks count

The box is not the ideal size for this woofer. It was re-purposed from a former project. Life always gets busy near the end of summer and I ran out of time to build the ML-TL boxes that Paul Kittinger modeled for me. I will build them some day and I can forward that on to anyone who might be interested. As it stands, this box is 19L tuned to 45Hz. The baffle is 17" x 9.5" and there are a few small braces running side to side. The port is plain old 2" pvc, 4.75" long. F3 is around 49Hz and F10 is 35Hz. I stuffed the back 1/2 of the box with Wally World poly-fill. I'm guessing about 4 oz/box. They can get a bit boomy and thick if placed too close to the back wall because of this alignment. 16" out into the room would be the minimum I would recommend and at least 2 feet from the side walls. But if you get things right in your room, they sound pretty solid in the low end department, especially for a $25 woofer!

Here's a BOM. With current pricing, the cost has actually gone down just a bit - note the judicious use of surplus 10uF caps!

[Chris Roemer]

I thought I should finally post my Etude design from Iowa DIY for anyone who might be interested. An Etude is a musical composition written for the purpose of improving ones technique. The name is quite fitting, this being my first true solo design.


I used the 8" MCM 55-2185 DVC aluminum woofer. After the North D25 went NLA, I ended up choosing the Vifa NE19VTS in an effort to keep my costs under $150. This was designed and built to meet a price-point, the former Super Budget class, so this pairing of drivers is not ideal, but it works. I'm really pushing the NE19 to it's limits, crossing over so low, but I don't listen that loud here at home. And it never got ugly or made any disgusting noises (that I heard) in the gazillion cubic foot theater at Grinnell. I'm fairly certain one of the shortcomings of this design is less than perfect power response.

So here's the modeled crossover -

The BOX, Tom, what about the box? Even though your impedance plot doesn't LOOK like a vented box, it was, wasn't it? So . . . box dims, Vb, Fb, F3, driver spacings and offsets, lining/stuffing . . . ?

[maynardg]

Hey Tom, the Etudes were a star of the show in IA. SO much for so little. Congrats on a standout design.

[tom_s]

The BOX, Tom, what about the box?

Chris, You must have been posting as I put up the box info. You are right about the imp plot....doesn't look like a vented box I'll have to check into that. I might have used the wrong zma file in my sim

Maynard, thanks for kind words. Looks like I'll have to try to pull another rabbit out of the hat next year just to see if this wasn't just a lucky first shot!

[Pete Schumacher ®]

I'll echo Maynard.

That pair were the most surprising of the day to me. Overall, a nice balanced sound, far nicer than those drivers should be able to do. Says a lot for the guy who negotiated the deal between that 8" woofer and .75" tweeter.

[DjDisturbed]

They look good for such a cheap price.

[mzisserson]

There wasn't a dog in that room, but I was more impressed the farther down we went in cost. The expensive designs were all beautiful - but also very illustrative of the diminishing returns theory on loudspeaker design.

...Or it shows the system was not up to snuff to utilize what a better quality speaker can do! Come on Johnny, how can you make a statement like that with speakers like the Malbecs there?


That said, Tom, they look great on paper. I see some similarities to what I pull with my speakers in there (the BBC dip, the simple x-over, careful driver selection, etc.) I am always amazed at how much you can actually pull out of inexpensive drivers. Looking at your design, they are likely VERY good! I would not call them budget, (I guess I was expecting the woofer to be $15/ea and tweeter $10/ea), however once you get around $100.pr in drivers you can get some amazingly good results. I think you may have just hit the nail RIGHT on the head for anyone looking at a budget 8" 2-way!

The harshness, well, two things: 1) its $100 worth of drivers... 2) There is a rapid impedance/phase shift that occurs between 1.5 and 3K, you may be hearing that a little. It is likely at higher volumes as the speakers become more non-linear, it is a little tough for the tweeter. Just a thought for you to chew on.

Nice job man, I usually do not say much, but I am impressed with what I see here: common sense!

[johnnyrichards]

...Or it shows the system was not up to snuff to utilize what a better quality speaker can do! Come on Johnny, how can you make a statement like that with speakers like the Malbecs there?

I have no idea what you are implying, so I'll reiterate. I was more impressed the lower the price - there is not as much of a difference between todays entry level DIY and the high end stuff as people who shop price tags want to believe there is.

Maybe it was the 12awg zip cord most of used.

[mzisserson]

I was more impressed the lower the price - there is not as much of a difference between todays entry level DIY and the high end stuff as people who shop price tags want to believe there is.

Maybe it was the 12awg zip cord most of used.

Ok, my bad. I though you were saying there was not much difference between $ DIY and $$$ DIY. Using the 10x rule there is no reason if properly designed a $200/pr x-over & driver speaker should not copmpete in the $2k range of similar form function at retail. Its a good gauge to use, and well done if he made it (seems like he did!).

You would have heard greater differences with better speakerwire, AJ told me so.

[johnnyrichards]

Ok, my bad. I though you were saying there was not much difference between $ DIY and $$$ DIY. Using the 10x rule there is no reason if properly designed a $200/pr x-over & driver speaker should not copmpete in the $2k range of similar form function at retail. Its a good gauge to use, and well done if he made it (seems like he did!).

You would have heard greater differences with better speakerwire, AJ told me so.

No, I was saying that entry level DIY is closing in on high end DIY, in some cases the difference is between a 2-way and a 3-way, or the choice of a bigger woofer or a specific crossover topology. It was no coincidence that there was a rough correlation between price and physical size and/or driver configuration (2-way vs 3-way). The best designs all utilized a 3-way design, with large diameter woofers.

Entry level DIY is still very competitive with solid commercial offerings in the same price range - but the big boys are closing that gap every day.

I don't believe in the 10-1 ratio anymore. Maybe a sliding scale needs to be derived - my $75/pr Driscoll are a fine sounding speaker, but they are not in the same class as, say, a pair of Infinity Primus 360 or some of the other mid-fi towers - not to mention the multitude of exceptional $500-$750 commercial bookshelf speakers out there.

Tom did something he shouldn't have done, but it worked. It speaks volumes to his design potential as opposed to a guy like me who does things "by the book". It was a fine design that probably can't be improved short using a tweeter that can cross even a little lower - I still think the edge/brightness I was hearing was due to being off-axis and the tendency of woofer breakups in that plane to not be as suppressed as they are on-axis. If I had been in a sweeter spot, they probably would have been just fine, just fine indeed. As it is - they were an exceptional design given the cost.

And Tom - I prefer a slight hump from a "too small" cabinet. No need to change on my account

[B_Rich]

I thought those sounded great Tom! I know you were almost talking down on them half way through the show ("oh, I just brought those little cabinets over there" ) but I thought they did great!

edit: by the way, nice picture

[mzisserson]

No, I was saying that entry level DIY is closing in on high end DIY

For the sake of not turning this into a thread jack of a very good design. I will simply state I strongly disagree, and perhaps your expirences with "high end" DIY have been under less than desireable circumstances (be it venue, designs, assoiated equipment etc).

I find it hard to believe these would be close to a Malbec, Byzantiyums, Nao Note, Statemen Monitor etc....As you know, I am certinly no skeptic!

Not to downplay Tom's design, but there are limitations with inexpensive drivers, a good designers accepts that going into the design. It has been proven over and over that better drivers stay more linear as excursion increases, cones motions and breakups are more controlled, and the distortion is far lower. I am still sticking by the 10x rule, and if someone invests over $500, in drivers, they are going to hit some serious competition they may have never have heard. (JM Labs, Pro Ac, Upper-end B&W, etc) However a $100-$200 investment can get you a speaker than *can* be as good as some "high end" commercial availave at Beat Buy, or even some home theater B&M shops (Vienna acoustics, the commercial Sonus Farber stuff, Martin Logan, Boston, Polk, etc).

Its a slippery slope Johnny, but our defenitions in this world come from our expirences, and even today my definition of what is truly high end from the noise is constantly changes as I hear some amazing equipment that pushes the envlope. Most, fall way short... For the members who know me, they understand the perspective, do they all agree? No. That is fine, but the concideration is there, and its a different perspective that should be concidered as you like to give accolades to those who take their own path.

Interesting: Tom makes a good design breaking some rules that people get to *hear*, and they are believers, yet I still take ridicule for crossing the ND16 below 2500Hz. It flies in the face of the hard core numbers guys based on the fact that that tweeter should *never* be crossed that low... On paper...

Keeping OnT, Tom, do not confine yourself to "boxes", or the flavor of the week (like OB's or MLTL's), Use your instinct and push the envlope with your designs moving forward regardless of any ridicule you may recieve. Usually the result will always speak for itself. KISS everything as you have here. I have had many curmudgons tell me things I cannot do, yet work. There is the theory, and the real world. They cross at some point, and it is a delicate one to tip-toe.

So much for keeping it short.

[johnnyrichards]

but there are SOME limitations with SOME inexpensive drivers

Fixed that for you.

You know Mike, for a "slippery slope" arguing kind of guy, you deal in absolutes quite a bit.

[mzisserson]

Fixed that for you.

You know Mike, for a "slippery slope" arguing kind of guy, you deal in absolutes quite a bit.

You are impossible. If that is all you got out of it, that's fine, I really do not care, but I think Tom is on a very good path here regardless.

[johnnyrichards]

You are impossible. If that is all you got out of it, that's fine, I really do not care, but I think Tom is on a very good path here regardless.

Yes he is, of course you didn't hear them and can only speculate based on measurements and simulations

[Pete Schumacher ®]

Yes he is, of course you didn't hear them and can only speculate based on measurements and simulations

The comparisons at Iowa were not full enough. The limitations of lesser drivers do become more apparent as you push the volume.

While the Etude was a superb sounding system, I've no doubt that it would fall apart far more rapidly than any of the larger systems.

However, that doesn't take anything away from tom's stellar voicing of those two drivers. For smaller venues and lower listening levels, those are some excellent values.