Silly not-so-FAST

von Ah

Member
Paid Member
2008-02-20 6:33 pm
Maryland, USA
I cobbled together something I've been threatening for a while, and I like it.

I gutted a BIC DV62si, put in a PE buyout special 6.5" woofer (299-114), and slapped a TB W3-881si in the tweeter hole. The silly bit is I enclosed the TB in a coffee can inside the cabinet. :D Added cheap poly stuffing inside the can, cabinet, and port, secured the can to the cabinet as best I could with caulk and screws, and put a 5mH inductor on the woofer. Voi la! FAST on a whim and a budget. :D

I was biamping the two drivers at first with 2 T-amps (ta2020 on the woofer and ta2024 on the W3), but have resorted to running them both on the TA 2024 only. I'm quite happy with how that sounds. The source is now a newly VAMP'ed PogoPlug (VortexBox user forum - Logitech SqueezeBox replacement for under $30) feeding a Toshiba C15 Preamp which is sending a mono signal to the T-amp. One channel to woofer, one to full-range. The basement tunes for laundry duty have never sounded better (and sync'ed to the 3 Squeezeboxes upstairs)!

There is a tad bit of brightness from the TB and I think that must be related to baffle step or upper-mid reflection, and the el-cheapo cabinet is not braced enough, but I'm tickled pink on the success of my first FAST projekt. :eek:

Now to rework the other cabinet, and properly brace the cabinets... :rolleyes: This has been playing for several months, so the second phase will probably take me another year. :D
Here's a pic:
 

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Awesome. I like it! If you're willing, you could improve that cross over. 5mH plus 80uF on the woofer. 50uF plus 2mH on the TB. Reverse the phase of the TB. Should be about an LR2 around 500hz.

There is a tad bit of brightness from the TB and I think that must be related to baffle step or upper-mid reflection, and the el-cheapo cabinet is not braced enough, but I'm tickled pink on the success of my first FAST projekt. :eek:

I found this as well. It's quite slight, but glad you noticed. Some people like this kind of sound. It's not frequency reponse related. I doubt its cab related or reflection related. Not baffle step either because the way you've low passed your woofer. For me, it was pretty minimal and it was related to cone break up in the TB. It hides itself in the frequency response really well, but it's there. So there's some harmonic distortion and some CSD.

If yours is more than slight, it could be break up from both the TB and your woofer leaking through. If it's a cheap buyout woofer with lots of inductance, then 5mH won't be as effective as you might think up around it's break up of probably something like 5khz. 6db/oct isn't 6db/oct. Not unless you add a zobel. Combined with the fact that break up is commonly 10db above the median SPL, the break up may not be supressed at all.
 
Why don't they sell a fast speaker similar to this? I have an old (circa 1992) JVC stereo set that until recently, I did not realize it was a FAST system: qnty 2 x 3 in full range drivers with a bandpass labyrinth sub in the same cabinet. The full range drivers are encased in a clear plastic cylinder with some stuffing to isolate them from the sub cabinet. The thing is bi-amped with a Sanyo chipamp with an active crossover and equalizer. It actually sounded really nice except for rattle in sub cab due to lack of bracing.
 
Start of off topic

or a Volvo, in which case it's just broken in ;)
Well, several years ago bought a Citroen Xantia, driven about 200 000 km. Drove another 100 000 km without major problems.
But that one had the best speakers compared to later models. C5 series 1 had good bass but not so good trebles. C5 series 3 missed also the bass ...

End of off topic
 
I don't think the average consumer cares.
The average consumer is 20-50 and male. They don't care how big or ugly the cabinet is, they want the guts. They pull the grill cloth, they kick the tires and they want to see a tweeter, especially one with some serious sex appeal. More is better and it should be shiny too.
You put a grill cloth on it and no one would know the difference.
:confused:
Now we turn our attention to the 'Bose' market. Some come with non-removable grills. The speakers are often nice little things that can be tucked away. No, we don't care how they look so much as they must be small and either fit in with the decor or be mostly out of sight.

FAST Is for those who accept the FAST compromises. People who care about the sound are less than 5% of the market and in that 5%, only 10% of those agree that FAST is the answer.
 

von Ah

Member
Paid Member
2008-02-20 6:33 pm
Maryland, USA
Off topic is on topic in my thread!
Volkswagen I'd guess.
MPM was on the right track.
chrisb said:
or a Volvo, in which case it's just broken in ;)
I wish I had bought a 240 wagon instead 11 years ago. :cool:
barackuda said:
I bet golf MK 4 :)
barackuda nailed it. :yes: 2001 Golf GL. 2 doors, crank windows, manual transmission, bullet-proof normally-aspirated 2 liter 8 valve 4 cylinder. 115 hp of fury! :D

I agree that the FAST design is too much for the standard market to handle. Anything new to the consumer would get passed by, statistically. There's no way it would sell enough. More fun for us, then! :cool:
 
ODougbo - FAST is Fullrange And Subwoofer Together. It's a pretty cool design concept. It's sort of what many people do already using full range satellites with a separate mono sub. But in the case of FAST a sub, crossover and full range driver are built into the same cabinet. I want to build one as soon as I can.
 
FAST can also be done with line level crossovers (or active crossovers via miniDSP or op-amps) before the amps and done with bi-amping to avoid heavy expensive speaker level crossover components. I don't think there is a requirement that the woofer be in the same cabinet for it to be called FAST. Fullrange Assisted (or And) Subwoofer Technology? Not sure which is exact acronym but you get the idea that the sub is crossed real low so that the critical wide band from ~200 Hz to ~15 kHz has no crossover to mess with critical phase and spatial imaging information.
So you get the benefits of a full range and the pleasing bass extension of a fat woofer. It sounds really good.
 
I need to pipe in with my one and only speaker idea today.....:Pinoc:

Von, need to build this box with 1/2" bb plywood.

1/2" mdf is over $30 now, the 1/2" bb is only $40; could easily build one out of a 5' x 5' sheet.

You'll have a box that will really chug along and it wont weight much at all.

(Plans/design by NeoDan)
 

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It's not that prescriptive.

There's no requirement for the fullrange and woofer to be in the same cabinet. There's also no requirement to have a subwoofer as opposed to a regular woofer that can fill in the lower registers.

It's simply adding a woofer to augment the fullrange (as in single driver rather than full range as in a 2 way satellite) and relieve the full range of the lowest octaves. Separated from a typical two way in that the crossover is minimalist / PLLXO or similar.


ODougbo - FAST is Fullrange And Subwoofer Together. It's a pretty cool design concept. It's sort of what many people do already using full range satellites with a separate mono sub. But in the case of FAST a sub, crossover and full range driver are built into the same cabinet. I want to build one as soon as I can.
 
FAST can also be done with line level crossovers (or active crossovers via miniDSP or op-amps) before the amps and done with bi-amping to avoid heavy expensive speaker level crossover components. I don't think there is a requirement that the woofer be in the same cabinet for it to be called FAST. Fullrange Assisted (or And) Subwoofer Technology? Not sure which is exact acronym but you get the idea that the sub is crossed real low so that the critical wide band from ~200 Hz to ~15 kHz has no crossover to mess with critical phase and spatial imaging information.
So you get the benefits of a full range and the pleasing bass extension of a fat woofer. It sounds really good.

I thought it was Full range Assisted by Subwoofer Technology.

Either way, it does sound good. :yes: and if the full ranger is really good then the crossover can be down below 80, which is even better. At that point you don't even need a traditional crossover, per se. Just blend the sub in (paying attention to phase!) and enjoy.
 
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fastbike1 - simply adding a woofer would not be quite right. The whole point of the design philosophy is to keep crossover delay and phase shift well out of the all important mid range. In order to do that you truly do need low subwoofer crossover points. Perhaps a 1st order xover at higher point could sound OK. But there is an 'S' in FAST for a reason. It's not a FAWT.