Parts Express Amp (1 Viewer)

[JayDaniel]

Hey guys, I've been considering building my first DIY 10" or 12" sub. I rec'd my Parts Express Flyer yesterday, and they have their 120 watt sub amp on sale for $79.
http://www.partsexpress.com/pe/pshow...number=300-792
Would this be a good start on my first DIY sub? Secondly, the description says 120 watt sub, but the specs read 110 watts RMS into 8 ohms @ 0.1% THD. Why the difference? Just wondering.
Would you recommend pairing this up with a Dayton driver?
Thanks.
JayDaniel

 

[Anthony_Gomez]

I am not sure about the 120 vs 110 thing, but don't worry about it. It is only a fraction of a decible difference.

This amp should be fine for a beginner budget project.

If you have the money, you may want to look at their 250watt amps.

 

[Brian Bunge]

Jay,

Dustin used that amp with a Dayton DVC 12" woofer in a ported enclosure (125L, tuned to 20Hz IIRC) and it sounds like he got excellent results. He did disable the bass boost though, so if you went this route you'd definitely want to do that.

Brian

 

[Peter Jessee]

Would this be a good start on my first DIY sub? Secondly, the description says 120 watt sub, but the specs read 110 watts RMS into 8 ohms @ 0.1% THD. Why the difference? Just wondering.

PE rates their amps for their 4 ohm power, not 8 ohm, since most popular sub drivers are either 4 ohm or dual 8 ohm voice coils. I think it's rated at 156 watts @ 4 ohms, so the "120 watt" description is conservative. I've used this amp with a 4 ohm car driver and a Dayton DVC 12", and it sounded fine with both. At $75, it's a great deal.

You can modify the bass boost/rumble filter if you're handy with a soldering iron. I'm not sure if these have the 5-6 dB bass boost @ 30 hz, or the flat response like the 300-794.

Peter

 

[Hank Frankenberg]

Yes, Jay, this is one of life's pleasant no-brainers. Go for it.

 

[Ryan Schnacke]

It's rated at 120 watts into 4 ohms - meaning its designed to produce (at least) that much power. Under some test condition at least one sample was found to produce 156 watts into 4 ohms. This does not mean that it is rated at 156 watts or that all samples will perform that well.

Now that I've vented ... I've got one of the 250 watt amps and its a real bargain. Runs warmer than the plate amp on my SVS but performs just fine and what a bargain!

 

[Brian Bunge]

Also, the 300-794 amp is rated at 250W, but an independent test showed that it measured 280W. While not a huge increase, I'd rather have a conservative rating than an inflated one.

Brian

 

[Darren_T]

Just a bit of info and a question for everyone else. I have the PE 250W amp in my Tempest Vented Adire Alignment sub and I can't turn the thing up past 1/4 gain when it is calibrated or it will have too much output. I can crank the amp all the way up and it works great but for a properly calibrated sub I doubt you'd use all the amp has to offer. I suppose if you had a huge room you might use 1/2 to 3/4 gain.

Is this what most have found with their amp in a Tempest vented enclosure?

Darren

 

[Ryan Schnacke]

"The sub gain knob is NOT an indication of how much headroom you're using." -- That's going to be my new motto.
There's 3 gain controls in your system: The sub gain control, the receiver's sub level and the receiver's volume knob. Increasing any one of those will increase the amount of power you're using and reduce the leftover headroom. You could have the sub gain at 1/4 and still push it to (or beyond) its limits by cranking the volume and the receiver's subwoofer level.

I can crank the amp all the way up and it works great but for a properly calibrated sub I doubt you'd use all the amp has to offer.

Did you have your receiver volume at the loudest position you'll ever use when you cranked the amp? If so then more power to ya. If not then how do you know that you really have that much headroom?
And whats earth-shattering in a 2000 cu ft room may be only moderate in a 6000 cu ft room with openings to other areas of the house ... like mine:frowning:

 

[Brian Bunge]

And whats earth-shattering in a 2000 cu ft room may be only moderate in a 6000 cu ft room with openings to other areas of the house ... like mine

You're not alone, brother! :frowning: That's why I want an Uber15!!!!!!!!!!!!!!!!

 

[AndersP]

I would go for the bigger amp most definately.
DIY is a lifelong contagious disease for which there is no cure and your next sub project being a smaller, less powerdemanding application is a concept of a very low order of probability.
Good luck and best wishes!!
Anders

 

[Darren_T]

Yes, all of my experimentation was at reference level...higher than I ever listen to for extended periods. The receiver LFE level was at 0. I use the sub gain to calibrate because I don't like turning down the LFE. My room is 13X15X9 and is open ended so the actual room is 30X13X9 with an open corridor. Big room, probably bigger than most since the corridor has a 20 foot ceiling.

Darren