# Who wants to test out/review a Rockford pbr300x4? ChrisB?



## JAX (Jun 2, 2006)

I ordered one. Not so much in a hurry to get it in car since car is not ready for any amp. Thought I might see if we can get a review by a trusted member and see what these are about. 

I bought one but it's not here yet . The closer you are to me the better. No newbs need ask. 

Unless you guys want to pitch in and buy one as a group. Right now there are some cheap ones for sale


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## Chaos (Oct 27, 2005)

They are about 75x4 @ 4 ohms 

Seriously though, like I said in some other posts, we have already installed a handful of the PBR amps in a few motorcycles. So far, they sound pretty good. 

Can't really tell any significant audible difference between these and a 'typical' full-range class D, but I suppose that time will tell how well they hold up.


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## JAX (Jun 2, 2006)

See that's it. I don't know how different a car install sounds versus motorcycle and nobody that may have installedin car has provided details. 


I couldn't decide so I tossed coin and bought it. It was not my first choice but the size and supposed efficiency were great. 

T
I thought it would be good to get a review from someone who has a system and can compare


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## ryan s (Dec 19, 2006)

Crazy how this BR class works...


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## ChrisB (Jul 3, 2008)

My HD900/5 will be here on Friday.

Then again, that Rockford is cheap enough to buy one "just because".

Edit: On second thought, this has me a little concerned about the Rockford: This amplifier is only capable of operation at 4-Ohms


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## JAX (Jun 2, 2006)

You want to test out the br?


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## ryan s (Dec 19, 2006)

The mono is 1-4 ohms stable...and how many around here would use the 4 channel at anything but 4 or 8 ohms?


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## ChrisB (Jul 3, 2008)

I was worried from the other direction when I saw 4 ohms. It made me think about some of the older class D monoblock amps that would oscillate and produce feedback on 8 ohm loads. My full range driver options for the car are either 6 or 8 ohms.


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## Ziggy (Nov 29, 2007)

hmmm... boom cooler amp?


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## ryan s (Dec 19, 2006)

Contact RF? 

Or get one hooked up to see...it was hard enough trying to find out exactly how the BRT worked and I'm still a bit confused.


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## RedMed427 (Feb 9, 2007)

Man that rockford interview sure peaked my interest!


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## cleansoundz (May 14, 2008)

That RF amp is still a class AB amp. Can't wait to hear the test results.


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## JAX (Jun 2, 2006)

Sold mine. So it will need to be tested elsewhere.


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## topdawg (Jan 13, 2011)

My brother-in-law was looking at one of these for his install, I was looking forward to hearing what you thought!


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## jac09g8gt (Mar 7, 2011)

Jax,

I am only an hour away from you. Once I get it from you and put in I will gladly meet up with you and let you see how it works out.


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## envisionelec (Dec 14, 2005)

It's an audio level-dependent charge pump. It's definitely a unique application, but not at all advanced in terms of the technology. 

I like it, but it is limited in its applications. They're grabbing market share without trying to be me-too. 

I love how the designer is straightforward about the product. Not much to say beyond "this is how it works". Notice the _lack_ of marketing terms.


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## envisionelec (Dec 14, 2005)

cajunner said:


> looks like a sweet topography.
> 
> charge pump architecture is a new one for me.


It's used a lot in situations where you don't have a negative rail like in digital applications that has a downstream DAC. Chopper amplifiers are basically charge pumps that stabilize its operating point. A tiny charge pump is used in the Alpine headunits' ICs that required a 20A fused line straight to the battery. They pumped the rails to +/- 8V or so (up from +/-6) to eek out a few more watts. It wasn't as dramatic, but it did increase headroom over a regular headunit. It was also one of the first ICs to be specified at a 2 ohm load. It wasn't Alpine's design, but ST Semiconductor. 

This is not the first time I've seen a swinging negative rail - but it is the first time I've seen both the switching rail and the charge pump used, simultaneously. I bet it's awesome!


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## jac09g8gt (Mar 7, 2011)

I will be putting one in my wife's solstice GxP tomorrow afternoon. I will post my thoughts.


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## jac09g8gt (Mar 7, 2011)

I just finished installing this amp and I have to say it really impressed me. It is very clear and powerful. I am sold on it and about to purchase another for my car, since this one went into my wifes car. She has a solstice gxp, so there is no room for extras in the car. This amp fit perfectly behind the seat of this two seater. It really amazed me.


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## cleansoundz (May 14, 2008)

Good to hear. Does that amp produce a flat signal? Does it appear to have a treble boost like the latest crop of RF amps?


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## jac09g8gt (Mar 7, 2011)

Im about to take the car for a ride now, I'll let get to hear it loud now. I finished late last night and I'm in a subdivision, so I didn't turn it up too high.


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## jac09g8gt (Mar 7, 2011)

Everything stays level, there are no peaks. I'd suggest this to anyone, whether you have a little space or a lot.


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## oldno7brand (Mar 15, 2011)

Maybe I am a bit nuts but I would like to see a Power 1000 type amp with this technology.

Or if only the punch 45/75/150 reissues had boosted rail

Mua ha ha ha


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## jac09g8gt (Mar 7, 2011)

I am still enjoying the power this little amp pushes out. I have been playing several types of music on it and I have not had a complaint yet.


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## envisionelec (Dec 14, 2005)

oldno7brand said:


> Maybe I am a bit nuts but I would like to see a Power 1000 type amp with this technology.
> 
> Or if only the punch 45/75/150 reissues had boosted rail
> 
> Mua ha ha ha


They do have "boosted rail", it's called a transformer. 

But seriously, there is no benefit to this technology beyond this power level. Or in other words, the limiting factor is the input voltage. It's taking a single-ended voltage (in this case 12-14V) and "flipping" the power supply polarity every half wave according to the audio signal. Well, they're not really flipping it because it's ground referenced - they are floating the audio output through a set of FETs so that neither positive or negative terminal is at ground potential at any time.

If you were to require more than double the vehicle voltage, then you need some kind of transformer or boost inductor to achieve higher wattage. I can see them using this trick in a higher power amplifier WITH a transformer, but that is their Class BD.


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## Radioteacher (Aug 4, 2011)

jac09g8gt said:


> I am still enjoying the power this little amp pushes out. I have been playing several types of music on it and I have not had a complaint yet.


Thanks for the write up. I bought the pbr300x4 2 weeks ago and received it on Monday. I am hooking it up on my 2008 Victory Vision motorcycle this weekend to new speakers since the OEM are awful. 

My only question is....if I use the high-level inputs (by cutting off the low-level inputs from the supplied cable) and connect them to the OEM radio speaker cables (after disconnecting the OEM speakers) and connect the output of the amp to the new speakers, Do I need to use load resistors on the OEM speaker lines?

I am worried that I could hurt the OEM amp by not providing it a proper load since it will not be driving speakers anymore. 

Take care,


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