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[FAST380]

I grabbed these specs from the various web sites. I am not an expert, but I do know one 75 watt a channel amp may be something totally different than another 75 watt a channel amp, it is all in how they rate them. I am sure there are other factors, but this is what I read:

Hawg Wired = 75w X 4 @ .010 THD List price $999.95
Rockford Fosgate = 75w X 4 @ .5% THD (50 X higher than HW) $269.99
J&M Audio = 75w x 4 @ 1% THD (100 X higher than HW) List price $769.99

Get what you pay for??

My thought is the HW is going to be cleaner, and go louder for the same "rating". I am curious what some of the experts out there have to say about this.

Thanks for your input!!

Hawg Wired
PSC3004 Specifications
Input Channels: 4 High/Low Level
Output Channels: 4 Channels, 1 Sub
Nominal Output Impedance: 4 ohms
Nominal Power Output (Watts RMS): 300 Watts (75Wx2, 75Wx4, 60Wx5)
Frequency Response: 10Hz-50kHz
Low Level (RCA Line-In) Sensitivity: 200MV – 6V
High Level (Speaker-In) Sensitivity: 400MV – 12V
Input Impedance: 33K ohms
PSC3004 Dimensions: 6.50”W x 3.75”D x 1.50”H
PSA75 Dimensions: 2.75”W x 3.00”D x 1.30”H

Class-T® Amplifier Sound Quality Typically:
00.005% THD+N @ 70W 4 ohms
00.010% THD+N @ 75W 4 ohms
10.000% THD+N @ 117W 4 ohms
Dynamic Range: 103DB
Over-Current & Over-Temperature Protection
Turn-On & Turn-Off Pop Suppression

Rockford Fosgate
MODEL- PUNCH PBR300X4
Continuous Power Rating (RMS) - Measured at 14.4 Battery Volts
4 Load Stereo 75 Watts x 4
Dimensions: Height 1.53" (3.90cm)
Width 4.25" (10.8cm)
Length 6.75" (17.2cm)
External Battery Fuse Rating 30A
“A” Weighted Signal to Noise Ratio
Referenced to 1 Watt into 4 ohms ≥80 dB
“A” Weighted Signal to Noise Ratio
Referenced to rated output into 4 ohms ≥100 dB
Crossover Slope 12dB/octave Butterworth
Crossover Frequency 80Hz LP/AP/HP
Frequency Response 20Hz to 20kHz ±1.0dB
Signal Voltage Adjustment Range Variable from 150mV to 11V
Protection Short circuit protection shut downs the amplifier in
case of very low impedance, shorted speaker wires, or
shuts down the am pli fi er in case of overheating.
Input Impedance 20K ohms
Operating Voltage 9 to 16 Volts DC
CMRR (Common Mode Rejection Ratio) >55dB @ 1kHz
Damping Factor >200
THD+N (Total Harmonic Distortion+Noise) < 0.5% @ 4 ohm
These specifications are Amplifier Power Standard CEA-2006 Compliant

J&M Audio
ESPA-5000
Full Range Class G Amplifier
Output Power (RMS) @ 1% 1000Hz 14.4V CEA 2006
Stereo @ 4ohms 4 x 75 watts @ 13 amps Eff 71%
Stereo @ 2ohms 4 x 125 watts @ 23 amps Eff 66%
Frequency Response -3dB 1Hz - 69kHz
S/NRatio
Separation >90dB
>74dB
Input Sensitivity .35V - 3.9V
Input Impedance 47.5K

[Harleypingman]

I'm not a tech or audio professional, but I've found "Basic Car Audio Electronics" to be a useful source of information.  Using the search term THD, this is what it says:

Total Harmonic Distortion:
When an amplifier is driven with a signal, the output of the amplifier is an amplified version of the input signal PLUS any distortion created by the amplifier. All amplifiers and signal processors add distortion to the signal. The levels of harmonic distortion in a high quality amplifiers are sooooo far below audibility that they are basically of no concern. When someone tells you that one amplifier is definitely going to sound better because its THD is rated at .002% vs an amp with .05%, you can be pretty sure that he doesn't know what he's talking about. Many people believe that THD below 1% is not audible and I believe they're probably correct. The fact is, especially in an automobile, the amplifier is the least of your worries. Speakers used for mids and highs commonly produce between 1% an 5% THD and for subwoofers the numbers can easily reach 10%. This doesn't even take into account all of the resonances of all of the plastic and metal panels in the vehicle.

http://www.bcae1.com/

If distortion from the amp  is "the least of your worries" in an automobile, I can infer that it's even more "least" of my worries on a motorcycle.

I've used the RF PBR300x4 on my '04 EG for the fairing and fairing lower 6.5" speakers and have been pleased with its performance; and, more recently, installed a second one for speakers in the HD saddlebag lid speakers and tour pak speaker pods, though I have yet to complete the install and have a road test.

Carl

[FAST380]

Interesting, I would fall under that category, putting to my emphasis on THD. I remember back in my earlier years I worked at a car stereo shop. There were amps that weighed 2 pounds and put out a claimed 1000 watts, then there were amps that weighed 10 pounds and put out a claimed 50 watts, and the 50 watt amp was the one you wanted. I wish I was smarter than I am  Looking at the specs, how does a person tell if the $1000 amp is better than the $250 amp??

[Jerry/MD]

Carl said it all. I've worked on amplifier circuits for 25+ years. The THD argument always makes me chuckle. The human ear just can't tell the difference in most cases. And yes, the system performance is limited by the worst performing component. In most cases, that would be the speakers.

Jerry

[Harleypingman]

Jerry, I was just ready to type a reply when I got the message that another reply (yours) had been posted.

The limiting factor in most installations (not that I'm expert, because I'm NOT) is the speaker--as you said.

Better to spend the $$$ on the speakers than the amp is the conclusion I've come to after reading and listening to motorcycle audio.

Carl

[Jerry/MD]

Jerry, I was just ready to type a reply when I got the message that another reply (yours) had been posted.

The limiting factor in most installations (not that I'm expert, because I'm NOT) is the speaker--as you said.

Better to spend the $$$ on the speakers than the amp is the conclusion I've come to after reading and listening to motorcycle audio.

Carl

Agreed. Electro-mechanical devices like speakers have limitations in achieving good THD performance. Adding to the problem is the fact they need to be weather-proof for a motorcycle. It's all about compromise.

Not to beat a dead-horse but people would be amazed at how bad THD (Distortion) must be before they can actually hear it. I've done this experiment in the lab, and even I was shocked. I don't remember the numbers, but it was orders of magnitude worse than what I expected.

Jerry

[Jerry/MD]

Interesting, I would fall under that category, putting to my emphasis on THD. I remember back in my earlier years I worked at a car stereo shop. There were amps that weighed 2 pounds and put out a claimed 1000 watts, then there were amps that weighed 10 pounds and put out a claimed 50 watts, and the 50 watt amp was the one you wanted. I wish I was smarter than I am   Looking at the specs, how does a person tell if the $1000 amp is better than the $250 amp??

FAST380,
That's a tough question. As I have said on previous posts...I've been involved in amplifier circuit design for many years. What drives product cost are two factors, design time and the price of the components. I've learned over the years what parts to select for good THD performance. A $.25 capacitor will do the job, but a $2.50 device will achieve better results. I have no doubt that the THD specs on the $1000 amp are much better than the $250 one. The manufacturer probably went to great pains to get that level of performance. The question is, can you actually HEAR a difference? A side-by-side comparison is the only way to tell.

[TIF2]

My two cents:

Of the 3 amplifiers listed above, only one of them has tested their amp to CEA Standards and received CEA-2006 certification and that is the Rockford PBR300/4. Not saying the J&M and the Hawg Wired don't do what they say they do, just wondering why they haven't had their testing methods cerified compliant with CEA. Seems to me it would be a critical selling point.

The Rockford has been tested and certified for power rating and THD at rated power. For the others, it is merely the manufacturer claiming the specs listed.

Ditto on the THD as being audible (I remember something like 5%) and the fact that speakers will play a major role in the outcome of a system's quality.

[Harleypingman]

A neat feature of buying the RF PBR300X4 is that you get a certificate from RF certifying your amp's performance tested per CEA.

As mentioned, are you paying for (or considering paying for) something you cant't hear?

And, why don't others publish CEA compliant test data?

Carl

[mrmagloo]

My two cents:

Of the 3 amplifiers listed above, only one of them has tested their amp to CEA Standards and received CEA-2006 certification and that is the Rockford PBR300/4. Not saying the J&M and the Hawg Wired don't do what they say they do, just wondering why they haven't had their testing methods cerified compliant with CEA. Seems to me it would be a critical selling point.

The Rockford has been tested and certified for power rating and THD at rated power. For the others, it is merely the manufacturer claiming the specs listed.

Ditto on the THD as being audible (I remember something like 5%) and the fact that speakers will play a major role in the outcome of a system's quality.

Interesting topic and was wondering, I know J&M amps are made by ARC.  I thought ARC's were certified?  Also, has anyone tested the RF vs the ARC/J&M?  I think we've seen plenty of J&M out performing HW and HT, so it would be interesting to see where RF fits in?

And, what about this new amp technology that is supposedly starting to come down the pike? I forgot the name, but supposedly much more power, much smaller, less heat, etc. Holy Grail for bikes.  Any ETA on that stuff showing up any time soon?

Thanks guys.

[TIF2]

Interesting topic and was wondering, I know J&M amps are made by ARC.  I thought ARC's were certified?  Also, has anyone tested the RF vs the ARC/J&M?  I think we've seen plenty of J&M out performing HW and HT, so it would be interesting to see where RF fits in?

Thanks guys.

I have tested the Arc 125.2 (not the 125.4) and the RF PBR300/4 on the same bike through the same speakers. They are very comparable in performance (assuming, of course, that the 125.4 is merely a 125.2 x 2 in the same chassis). If you need 4 channels of discreet amplification, I give the nod to the Rockford for price and ease of install, and to my ears it out-performed the Arc 125.2 when driving the same speakers. However, it needs to be noted that when using the PBR300/4, you must use the speaker level inputs and not the RCA low-level as the output of the Rockford suffers when using the RCA's. Since I am using the stock H/K - this may not be the case for aftermarket decks. In looking at the design of the RF amp, my feeling is that using low-level inputs to the amp will always produce lower output than when using the speaker-level iputs to the amp.

For now, the Arc 125.2 still has place and remains a great amp solution for the following reasons:

1. It is 2-ohm stable so connecting to factory HD (2-ohm) speakers remains an option. (Not sure why one would want to keep factory speakers )

2. Because it can drive a 2-ohm load, it allows for parallel connection of 4-ohm speakers without needing a 4 channel amp (say - fairing and lowers). This is an attractive feature for SESG2/3 owners that want to upgrade the fairing and lower speakers but want to use the factory wiring.

3. It has a proven history of being a reliable amp.

Unfortunately, Arc will need to "up the ante" for the 125.2 come May/June when the new RF PBR300/2 amp becomes widely available. The new RF amp will be CEA-2006 certified, it will be 2-ohm stable, and is rated at 100w/ch at 4ohms and 150w/ch at 2ohms. The list price is at $269 so expect the final street price (September maybe?) to be around $200.

Anyway, when comparing the RF 300/4 to the Arc 125.4 getting the Rockford (to me) is a no-brainer simply due to the fact that it is MUCH cheaper, produces excellent sound, and drops on top of the radio with ease. Although, getting TWO of the RF PBR300/4 amps on top of the radio requires significantly more work - eh Carl?  . The fact that the RF amp is limited to a 4-ohm load is clearly not a show-stopper (for me) as the VAST majority of quality aftermarket speakers are 4-ohm rated.

These are just my findings/opinions ... hope it helps.

[hacksaw]

I've been trying to decide on which amp and speakers so I've been doing a little research myself.  I do know that the ARC amp's have an internal cooling fan on them, is this something to look at also??

[mrmagloo]

Thanks alot TIF2 - It's always enjoyable and informative to read your posts!

Quick follow up.  I do have the complete J&M 125.2 set up, with the stock head unit, the 7.25 Rokkers in the Fairing, and in the Lowers. I also have the Rokkers in the back. The stock amp runs the lowers and the rears.  Obviously, the 125.2 is only powering the Fairing, which is normal. However, I've come to realize that the lowers are pretty much worthless as the output is much lower than the fairing with the higher output. So, I have been contemplating upgrading to the 125.4 to run the Fairing and the lowers to hopefully pull a little more. However, as you mentioned, that 125.4 is a pricy upgrade that I'm afraid isn't going to produce a big enough bang for the buck.

That Rockford 300/4 sounds interesting, but do they have plans to make it 2ohm stable in the near future like the 300/2?  I think with the J&M speakers, I really have to wait for that, provided that's coming somewhere in the near future?

Also, do you know anything about this new amp spec that someone posted here a while back that is supposed to drastically change the amp tech for the bikes soon. I wish I could find that post again!

[sleepybare]

Not meaning to change the topic of this thread but, I am looking to keep the existing sound system in my 2007 and only looking to upgrade the speakers in the dash. Is there a general consensus as to the best speakers which would be compatible with the existing system?

[TIF2]

Quick follow up.  I do have the complete J&M 125.2 set up, with the stock head unit, the 7.25 Rokkers in the Fairing, and in the Lowers. I also have the Rokkers in the back. The stock amp runs the lowers and the rears.  Obviously, the 125.2 is only powering the Fairing, which is normal. However, I've come to realize that the lowers are pretty much worthless as the output is much lower than the fairing with the higher output. So, I have been contemplating upgrading to the 125.4 to run the Fairing and the lowers to hopefully pull a little more. However, as you mentioned, that 125.4 is a pricy upgrade that I'm afraid isn't going to produce a big enough bang for the buck.

A good stop-gap solution for you would be to wire your fairing speakers and your lower speakers in series and drive them with the 125.2. Since the Rokkers are 2-ohm nominal, this will create a 4-ohm load to the Arc. It will make a tremendous difference with the fairing and lowers receiving the 75w/ch output of the Arc at 4-ohms.

That Rockford 300/4 sounds interesting, but do they have plans to make it 2ohm stable in the near future like the 300/2?  I think with the J&M speakers, I really have to wait for that, provided that's coming somewhere in the near future?

For now, the PBR300/4 remains a 4-ohm only amp. I highly doubt they will come out with a 2-ohm stable version, but I have no "inside knowledge" so anything is possible (my speculation only here). The big issue for you are the Rokkers in the pods as they are 2-ohm as well. One possible solution is to replace the Rokkers in the pods with a set of Polk Dxi650 (4-ohm), keep the Rokkers in the fairing and lowers wired in series, then drive them with a PBR300/4. You'll be a happy camper 

Also, do you know anything about this new amp spec that someone posted here a while back that is supposed to drastically change the amp tech for the bikes soon. I wish I could find that post again!

If you're referring to a post I did a few months back regarding the new Hertz digital amps (and the Polk Audio derivative) then I just might (lol). Both of the initial amps are WAY awesome (and I'm excited about where they might go in the future) but the limiting factor is current draw. The Hertz amp specs show max current draw at 50 amps. Hard to put them on a bike that has a 45 amp generator.  Too bad as I was going to buy one to test it out.

Now if I can just figure out how to get an Audison "Bit One" in the faring .....