Rockford Fosgate Punch 150HD vs. Phoenix Gold MS-275?

[bigdwiz]

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I recently decided to put together a series of videos comparing the Punch 150HD and Phoenix Gold MS-275. Obviously, most members of this website would prefer the PG over the RF, but I attempted to be unbiased in my review as I'm a big fan of both mfg's and their amps



The first video is basically on overview of each amp, history and some detailed information on the price, power, design and more. After posting the video and doing some more research, I found the MS-250 in a 1989 Audio magazine's "Car Stereo Directory", so the MS series must have hit the market in 1989, not 1990 as I state in the video . We'll consider this "close enough".

The next video in the series will demonstrate RMS power output using my Test Bench and I'll also test each amp with a subwoofer. I appreciate any comments you may have.

See the video in 1080p HD here:

Rockford Fosgate Punch 150HD vs. Phoenix Gold MS-275 - Old School Amp Shootout

Or embedded below:

[bigdwiz]

My apologies, I just noticed the "Product Reviews" section and this should be posted there. Mods, feel free to move if this would be best.

[nutxo]

I liked the look of the PG amps. I was running PPI when the HD came out but opted for punch over PG in the next series of amps. The Fosgate amps were freakin monsters.

[bigdwiz]

I've got some bad news...the power output test will have to wait (at least for the PG). Upon closer inspection, the MS-275's caps have oozed just a little and I don't want to chance screwing up this beautiful board . It may be a few months before I get a chance to send the 275 to Valeks, so although not trying to keep everyone in limbo, but it's gonna have to wait. Sorry dudes. In the meantime, here are the RMS power output results from the RF P150HD:

1991 Rockford Fosgate Punch 150HD

Measured RMS Power Output at 13.8v:

119w/ch @ 4ohms stereo
191.8w/ch @ 2ohms stereo
299.2w @ 4ohms bridged
330.2w @ 2ohms bridged

[dannos671]

Ahhh good stuff big! I am a big fan of both mfrs. and amps. It'll be interesting to see what the output is of the MS275.

[Eric D]

I have little experience with the 150HD, but I am going to guess you will find under load the 150HD has more output than the MS275, but the MS275 has a much higher unloaded output voltage. So, while listening to music the MS275 is going to sound louder when played to its extremes and below those extremes it will sound cleaner than the 150HD as well, as its output will clip later than the 150HD (with music).

Now with test tones, sine waves, and bass burping the situation becomes the opposite, as the MS275s rail voltage will probably sag down below the 150HDs normal level.

Some pointers regarding your review:

-The MS250 has a much weaker power supply section than the MS275. Their output sections are similar, but the MS250 has smaller components and a bit lower voltage. In other words, the MS275 is not a renamed MS250.
-At some point in time you could pick white or gray for the color, but I don't know when this was, or if the amp you have was during the time where you could get it in white as well.
-Making the adjustment to today's prices was an awesome point to make. It really shows how cheap today's audio equipment has become.
-The Punch 150HD is not all surface mount. It is mostly thru-hole just like the PG MS275, but has some of those little daughter boards in there which are surface mount. I suppose this could be called a "hybrid" design.
-To run the 150HD at a 1 ohm stereo or 2 ohm mono load pretty much required the use of the fan shroud which Rockford sold as an option. PG also sold this as an option for the MS275. The RF will cook eggs even with 2 ohm stereo loads, and going to 1 ohm will just make that worse. It does not have a lot of heatsink mass for the power it outputs.
-Great review so far though. Excellent attention to detail, and the fun part is, watching your review made me feel like I was back in the day when these amps were current models, which I too could not afford.

Can you post the unclipped output voltage of the Punch 150HD with no load?

[bigdwiz]

Eric D,

Thanks for the comments and corrections to my review. I should've known I would get called out on some of the technical details here with the experts... It's all good!

I'm planning on posting the P150HD's output video first, and my Velleman HPS50 does the wattage conversion for me, so I'll have to check and see if it had the voltage display during the test. I totally agree a test with resistors doesn't fully give "real world" results of an amp, but it does allow me a consistent method of testing all amps with the same parameters.

edit: I misread your question about posting the unclipped voltage with no load. I'll do this soon.

Thanks again for the comments and keep them comin'

[denim]

Fun video, great post Eric.

[bigdwiz]

I just completed the resistive power output test of my recapped MS-275 (thanks to Aaron at envisionelec.net). I didn't mention EricD's comments about (dynamic) music power vs. resistive power in the video, but did in the write up on my website:

http://www.oldschoolstereo.com/2011/08/ ... art-2.html

This is by no means and "end all, be all" test of the two amps, but does compare them using an unbiased method. The upcoming SQ test is more subjective, less scientific. The subwoofer test should be somewhat scientific as control over a sub should be relatively easy to compare (maybe, we'll see?).

I always appreciate the well thought out comments and questions from this forum and feel free to provide any and all constructive criticism. Also, I'm planning on using multiple cameras in upcoming videos for the output tests so you can see something other than the screen on the o'scope!

See the HD version on YouTube here:

http://www.youtube.com/watch?v=qNgBN5TCZBg&hd=1

Or, watch the embedded video below:

[nutxo]

No surpirises here. Meh. Nice Video man.

[marko]

loving the Hifonics amps, they are all underrated, the Thor is a beast for it's size!

[Mr. Wild]

Keep 'em coming! I love staring at old skool phoenix _GOLD_!

Here's a question: Did you load both channels at 2ohm stereo? Because the results for both amps are a bit odd. 4ohm mono should be equal to 2 x 2ohm stereo since it's the same load from the amp's point of view.

Also I must say you allow for a lot of distortion when measuring the RMS. Then I know it's impossible to measure THD with a basic oscilloscope. This probably answers my question. Its very difficult to make exact measurements by hand.

Measurements are measurements. I bet they both sound great.

[bigdwiz]

Keep 'em coming! I love staring at old skool phoenix _GOLD_!

Here's a question: Did you load both channels at 2ohm stereo? Because the results for both amps are a bit odd. 4ohm mono should be equal to 2 x 2ohm stereo since it's the same load from the amp's point of view.

Also I must say you allow for a lot of distortion when measuring the RMS. Then I know it's impossible to measure THD with a basic oscilloscope. This probably answers my question. Its very difficult to make exact measurements by hand.

Measurements are measurements. I bet they both sound great.

Thanks for the comments, I really appreciate them!

I didn't load both channels w/ 2ohm stereo tests b/c I don't have an extra bank of resistors for this test as of yet. I plan to get more resistors soon, which will allow for both channels to be tested in all ohm loads.

Yeah, the lack of distortion measurement bothers me as well. The Velleman HPS-50's screen is not the best resolution, so I'm having to make a best guess for when the waveform is clipping. It does have a USB output for monitoring via laptop, may try this to see if the waveform is easier to see. My father used to measure amp output, distortion, current, etc. for a living so I've been taking some pointers from him. I would REALLY like a THD analyzer and a better o'scope, but don't have the 1000's to buy those. Not to mention, this is a hobby right now, although a fun one!

I have had some of my results vetted in that my RF Punch 45HD I purchased in 1991 has the birth sheet. It stated 91.1w/ch into 2ohms stereo and I measured 90.9w/ch using my methods...not bad if you ask me. Also, the Punch 150HD in this demo put out 191w/ch according to it's birth sheet and my measurement was right on as well. I don't have anywhere near the equipment Rockford Fosgate has/had for measuring the output, but I feel confident I'm getting similar output results.

Also, I have (2) other MS-275's I'll test and see if there is any difference...just need to get those caps swapped out first!

-D

[bigdwiz]

loving the Hifonics amps, they are all underrated, the Thor is a beast for it's size!

Yes, they are quite impressive! I was very lucky to find the Vulcan and Thor VII's locally in such good shape. I was actually surprised the guy didn't have the boxes, based on the condition of both amps. He was 18 when he got them and now 38, so he took great care of them for 20yrs!

I have a Zeus VII currently being repaired by Stephen Mantz and should have it back next week. Steve has also agreed to an interview for my website, oldschoolstereo.com, so I'm working out the logistics now....very cool!

[marko]

I'm more into series viii but I do have a few series Vii, a Gemini and a pair of Olympus's, can't help but buy them when I see them cheap

your results are quite accurate, I remember the old 150HD was good for about 380wrms bridged mono so 191 @2ohms a channel is about right.

[lukeman269]

I like the videos man! I like watching this type of stuff. Like in your picture up top, I would have easily voted for the PG amp because of how awesome it looks, but after your test results of power output, it's amazing what power they can pack in such a small footprint. I got myself a pair of Rockford Fosgate amps that are supposedly underrated. One is a Punch X120.2 and the other is the X160.2. Both mint condition and I believe they were made back in '02? Not too sure. I should get some equipment to test em both out to see what they really push.

[bigdwiz]

I like the videos man! I like watching this type of stuff. Like in your picture up top, I would have easily voted for the PG amp because of how awesome it looks, but after your test results of power output, it's amazing what power they can pack in such a small footprint. I got myself a pair of Rockford Fosgate amps that are supposedly underrated. One is a Punch X120.2 and the other is the X160.2. Both mint condition and I believe they were made back in '02? Not too sure. I should get some equipment to test em both out to see what they really push.

It is important to emphasize what EricD mentioned about dynamic "music" power of an amp. Since speakers are essentially resistors, one would think the resistive test would be the best way to compare. However, it has been mentioned many times before, speakers impedance fluctuates during music playback and a static "load" of resistors can't take this into account.

Both amps power subwoofers great and sound tight, punchy and dynamic to me. It is funny to see some of the comments I get about the Rockford amp and people saying it is a "boat anchor" or something similar. What is their comment based on? Experience with a Best Buy RF amp from years past most likely. Again, I don't have a favorite between the two and there is no doubt the MS-275 would impress anyone who's never seen the "guts" of an amp (in addition to impressing those of us who have ). I think Rockford gets a bad rap in many people's eyes by preconceived ideas, not actual experience. I still have my Rockford Punch 45HD from 1991 and it still works 100% and spent YEARS powering subs at 1ohm loads.

BTW, I'm not experienced with those RF models you mention. I have a Power 550x from 2002, used in my daily driver since 2002...

Thanks for the comments!

[bigdwiz]

Here's a birth sheet from one of my Punch 150HD's...My PG MS-275 birth sheet only shows a distortion graph, not actual output numbers.

[Eric D]

Speakers are about as far from being resistors as you can get. Yes they have resistance, but that resistance is only from their voice coil wire.

Driving a resistor is very easy on an amplifier unless it is a very low resistance. In the case of a speaker, it has inductance, reactance, and a bunch of other things, which are difficult for an amplifier to correctly drive.

Personally, I don't care if an amp is power tested with a speaker, or a resistor, or something else, as I don't much care about raw power output of an amplifier. If I did I would not be using PG amps!

[Mr. Wild]

Interesting birth sheet.. No mention whether a mono or stereo load has been used. What also caught my eye is the freq. response curve. A little boost in the lower frequencies there, just like many listening tests have revealed. The efficiency is also very very good for an old class A/B amp.

[bigdwiz]

Interesting birth sheet.. No mention whether a mono or stereo load has been used. What also caught my eye is the freq. response curve. A little boost in the lower frequencies there, just like many listening tests have revealed. The efficiency is also very very good for an old class A/B amp.

The old RF birthsheets were done w/ 2 channels driven at 2ohms. And yes, the efficiency almost seems TOO high to be a A/B amp?

I have a birth sheet with my MS-275 as well, but it only shows a graph with output and distortion...doesn't give a read out of the actual test #'s (and the graph isn't exact enough to tell the wattage when distortion begins). I was curious if this was an original birthsheet or was it done after the fact? I'll see if I can get it scanned in to show you guys.