# cheap amp w/processing for yo horns



## Patrick Bateman (Sep 11, 2006)

In another thread, cajunner posted a link to an inexpensive amp with built in processing that might be a good option for horns. Here's why:

1) The amp is cheaper than almost anything you can buy outside of Walmart, just $25
2) It has a couple of processing modes built in. I am too lazy to dig up all the technical details but if memory serves, the first mode (SRS) uses crosstalk cancellation the increase soundstage width. This works well, particularly with speakers with excellent phase response, and it can create a soundstage that's wider than a car. It's similar in concept to ambiophonics and the Polk SRS stuff from the 80s. The second mode, called "FOCUS" claims to raise stage height. I don't know how it does this, willing to bet it has something to do with boosting 2-3khz.
3) Based on the size of the amp, it appears to be a real amp, not some cheap noisy chip amp

Just google vfx-4200 and you'll find the eBay auction. I bought two.

NuReality Introduces the First Car Audio Product to Feature SRS Labs' Revolutionary FOCUS Technology


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## SkizeR (Apr 19, 2011)

what the... why so cheap?


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## Patrick Bateman (Sep 11, 2006)

SkizeR said:


> what the... why so cheap?


because nobody puts amps in their car anymore?

The whole car audio market seems to consist of 0.01% of the population now


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## Victor_inox (Apr 27, 2012)

Patrick Bateman said:


> because nobody puts amps in their car anymore?
> 
> The whole car audio market seems to consist of 0.01% of the population now


and because there is no information about it on internet.


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## thehatedguy (May 4, 2007)

Because they are 20 years old.

And they are missing the controllers to use the "focus" settings...


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## cajunner (Apr 13, 2007)

they can be used without the remote, there are controls on the amp. You just can't turn off the Focus setting, (it's on at amp turn on) or toggle through the SRS in/out at the driver's seat.

these amps having SRS, even in a basic form is pretty much a lot of lycan's l-r difference signal, now if you were to tag this amp to 2 channels of a DSP and add the 20-25 milliseconds of delay to the signal, I believe they would do crazy things with the rear channels, in a good way.

The focus circuit, up front for the low kick/ foot well crowd, 8's in the floor, might do well on these too.

horns may not need a lot of lift, but the chance to use something like 8" pro coaxials in the floor, and have the stage rise up is intriguing to me, I can see a lot of potential in these amps.

too bad they only have a few, as some people might find they are all the processing required to make a low door mounted midrange sound completely convincing as an above the dash image can possibly be extracted from non-optimal speaker locations.


all the people doing a-pillars and fighting those reflective environments, may choose another path if they can do lower doors and not be penalized for low stage.


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## Patrick Bateman (Sep 11, 2006)

cajunner said:


> they can be used without the remote, there are controls on the amp. You just can't turn off the Focus setting, (it's on at amp turn on) or toggle through the SRS in/out at the driver's seat.
> 
> these amps having SRS, even in a basic form is pretty much a lot of lycan's l-r difference signal, now if you were to tag this amp to 2 channels of a DSP and add the 20-25 milliseconds of delay to the signal, I believe they would do crazy things with the rear channels, in a good way.
> 
> ...


The soundstage of my new speakers is as good as I've heard in a car.
Methinks eliminating early reflections is a pretty big deal, particularly in the two octaves from 150hz to 600hz.

Actually, I take that back, it's important from 150hz to 2khz, but it's easy to eliminate early reflections higher in frequency, waveguides aren't that big at those frequencies.

If you think about it, a lot of these processors that get you a huge stage are electronically eliminating some of the sound. For instance, ambio and SRS subtract information right channel information from the left channel, and vice versa.

But you can do it *physically* as well. That's what Polk did. And a dipole subtracts the energy radiated out to the sides.

But enough typing on the internet, I need to go measure my dipoles in the driveway. All the measurements I did on the patio are kinda junk due to early reflections.

Was talking to Jon Whitledge a few weeks back and he does his measurements in a parking lot at the top of a mountain, because the noise floor is lower. That dude takes this measurement stuff to a whole 'nother level.


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## douggiestyle (Apr 29, 2008)

I still have 6 iMac speakers gathering dust from your last recommendation, PB. 
Since these are NOS, any issues to be aware of, like leaky caps?


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## cajunner (Apr 13, 2007)

and if you need more power, there's no reason why you can't put these amps in, and tie in an LOC to their speaker outs in case you want their processing but need extra powah.

it might be a little noisier but getting stand-alone SRS processing with the feature set in these amps, is usually higher cost than the guy selling them on fleabay is asking.

think of it as a tweeter amp, that does the processing for your midbass, and amp the midbass appropriately.

As a pure amp, these appear to be quite a bit stronger than say, the output of any deck and at 60 watts of 1% @ 1K, tested, plenty enough to drive most wide-banders to their limits.


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