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]

Re: Etude - Super Budget 8" 2-way

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.

[[email protected]]

Re: Etude - Super Budget 8" 2-way

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

[tom_s]

Re: Etude - Super Budget 8" 2-way

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

[tom_s]

Etude - Part 2

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!:D

[Chris Roemer]

Re: Etude - Super Budget 8" 2-way

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]

Re: Etude - Super Budget 8" 2-way

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

[tom_s]

Re: Etude - Super Budget 8" 2-way

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 :o

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]

Re: Etude - Super Budget 8" 2-way

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]

Re: Etude - Super Budget 8" 2-way

They look good for such a cheap price.

[mzisserson]

Re: Etude - Super Budget 8" 2-way

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]

Re: Etude - Super Budget 8" 2-way

...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.:rolleyes:

[mzisserson]

Re: Etude - Super Budget 8" 2-way

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.:rolleyes:

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]

Re: Etude - Super Budget 8" 2-way

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]

Re: Etude - Super Budget 8" 2-way

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" :p) but I thought they did great!

edit: by the way, nice picture ;)