# Old School Amp Comparison - RF Punch 150HD vs. Phoenix Gold MS-275



## bigdwiz (Oct 7, 2010)

I recently completed the 2nd installment of my comparison of two VERY popular early 90's amps...The Rockford Fosgate Punch 150HD and Phoenix Gold MS-275.

The first video I did a few months ago is an overview of the design, price and installation differences between the amps. I'm fortunate to have MINT examples of both amps, so it will be like a trip back to 1991 in the DeLorean!

See the comparison video in HD here:

Rockford Fosgate Punch 150HD vs. Phoenix Gold MS-275 - Part 1 - Overview

or embedded here:







Now, onto the part many people are interested in...RMS power output! I used my Velleman HPS-50 and resistor load setup as seen here:

Testing RMS Power Output from Amps

Since pictures are worth 1000 words, I guess a video is worth more? Anyway, see the video below for the RMS wattage output comparison between the RF Punch 150HD and PG MS-275:

See the video in HD:

RF Punch 150HD vs. PG MS-275 - Part 2 - RMS Power Output Test

or embedded below:







Questions, comments or suggestions?


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## Chaos (Oct 27, 2005)

Dude, that's like comparing what's better:

Missionary or Cowboy.

Either way, it's a win.


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## bigdwiz (Oct 7, 2010)

Chaos said:


> Dude, that's like comparing what's better:
> 
> Missionary or Cowboy.
> 
> Either way, it's a win.


I agree, but a lot of the recommendations we hear on this forum are based on personal preference. I attempted to take out the ambiguity in this demo by using a scientific method to show the differences in the amp's outputs. Although I don't have $1000's of pro level test equipment, I have had several of my tests vetted by comparing my output to birthsheets received with the amps.

That said, I still prefer the PG's looks and ease of installation, but you can't knock the sheer output power of the RF (underrated by nearly half). You just don't see mfg's underrating amps these days, usually the opposite...

This is all for fun anyway, right?


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## DAT (Oct 8, 2006)

He'll of a job, I always knew the RF's were louder but the motherboard of the PG's were the sh1t back them in you wanted to display it. Either way you go they are classics.

Thanks Big D


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## bigdwiz (Oct 7, 2010)

DAT said:


> He'll of a job, I always knew the RF's were louder but the motherboard of the PG's were the sh1t back them in you wanted to display it. Either way you go they are classics.
> 
> Thanks Big D


Thanks DAT, I appreciate the comments. I agree, the PG just looks like it should sound better! The Rockford DSM series amps may be a closer comparison, but there was no 75x2 (rated) DSM amp. I have a 100DSM and it is even more powerful than the 150HD! 

A PG tech reminded me the MS-275 will put out more transient power, better for music dynamics. Unfortunately, I have no scientific way to measure this, so for now we'll have to go with the resistive power output.


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## Old Skewl (May 30, 2011)

Nice Job! Very interesting to see the results. How about a test of a Soundstream Reference 300 to compare also. If I remember right a magazine tested one back in the day and said it put out aprox 110 watts @ 4Ohms stereo.


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## bigdwiz (Oct 7, 2010)

Old Skewl said:


> Nice Job! Very interesting to see the results. How about a test of a Soundstream Reference 300 to compare also. If I remember right a magazine tested one back in the day and said it put out aprox 110 watts @ 4Ohms stereo.


Yeah, the SS Ref 300 would be a good comparison as well...Somebody send me one and I'll add it to the demo!

Thanks for the kind comments. I have a larger "stable" of 25x2 amps from the 90's I may test for power output comparison as well:

1) PG MPS-2240
2) Orion 225 HCCA
3) PPI Pro MOS 25
4) US Amps USA-50HC
5) RF Punch 45HD

I've already tested each down to 2ohms mono and know which one is the most powerful, but I need more resistors to add the 1ohm mono test for the one's capable (HCCA and MPS).


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## BurnOut956 (Sep 3, 2007)

Good aproach with the video. Nice job!


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## bigdwiz (Oct 7, 2010)

BurnOut956 said:


> Good aproach with the video. Nice job!


Thanks! I was going to add a HiFonics Ulysses VII to my 25x2 amps, but just got outbid on feebay  I had two, but both were non-working and traded them for some working amps...

Any suggestions on how to make future videos more interesting are greatly appreciated! I spend a lot of time watching other vids on YouTube and there are only a few I think are done well. Not tooting my own horn or anything, but these ingredients are very important:

1) High quality audio
2) Good, interesting content
3) High quality video (at least 720p)
4) Decent lighting

Steve Meade's videos are good b/c he makes them personal and interesting. I'm not big on the "hair trick" or "extreme bass" vids he does, but the other ones are interesting to me. Another user to check out is soundmancaraudio.


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## WRX2010 (Jun 11, 2011)

How about adding in an Audio Art 50HC?


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## SoundJunkie (Dec 3, 2008)

bigdwiz said:


> Yeah, the SS Ref 300 would be a good comparison as well...Somebody send me one and I'll add it to the demo!
> 
> Thanks for the kind comments. I have a larger "stable" of 25x2 amps from the 90's I may test for power output comparison as well:
> 
> ...


I may have a BNIB M&M 25 for you at a crackhead price if the guy accepts my offer for a group of amps! ZED built, should be a good contender in your 25x2 shootout! I will PM you if the deal goes through bro!

Sent from my DROIDX using Tapatalk


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## bigdwiz (Oct 7, 2010)

Yessirr....the M&M would be a great contender! I'll gladly add any other 25x2 pre-1999 anyone wants to donate or offer at a crackhead price! I also have a US Amps USA-50 I'll add in. Would also like to add a RF Power 50x2, Lanzar 50HC and maybe a Soundstream Class A 5.0.

PM me about the group of amps also, would like to know what you are getting into!


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## JAX (Jun 2, 2006)

nice job. It was nice to see the output of the 275. always wondered. knew it was underated but not how much. 

this would be cool to see some other amps tested.

anyone have a Adcom to lend to the test...? I would love to see the real life numbers on them. none of them were rated super high but from owning one I can definitely say it was way more than rated.


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## Viggen (May 2, 2011)

yes, I have a Adcom that I could -loan- for a test, love to see how it compares

GFA-5275 or a GFA 4404..... I guess I could send both if interested


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## Viggen (May 2, 2011)

O yea & if someone has a set of DIN/XLR cables, I could send a extra GFI-4600 as well


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## bigdwiz (Oct 7, 2010)

Hey guys, I like the idea of testing other amps as well, but for right now I'm going to do the ones I own. Although you may not be able to tell by the videos, these tests take around 1hr each for the setup/test, then another hour or more to edit and upload the videos. I'm considering offering this up as a service, but by the time you pay shipping both ways plus a few hours of my time, it ain't gonna be cheap...

Not to mention, I've invested a ton of $$ into the bench setup so I can test these amps (I'm not a technician, just a hobbyist). 

I do appreciate the offers to ship me amps, that's very generous! That said, anyone who wants to "donate" an amp to me for testing, send it on!


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## JAX (Jun 2, 2006)

bigdwiz said:


> Hey guys, I like the idea of testing other amps as well, but for right now I'm going to do the ones I own. Although you may not be able to tell by the videos, these tests take around 1hr each for the setup/test, then another hour or more to edit and upload the videos. I'm considering offering this up as a service, but by the time you pay shipping both ways plus a few hours of my time, it ain't gonna be cheap...
> 
> Not to mention, I've invested a ton of $$ into the bench setup so I can test these amps (I'm not a technician, just a hobbyist).
> 
> I do appreciate the offers to ship me amps, that's very generous! That said, anyone who wants to "donate" an amp to me for testing, send it on!



understand that ...


but the adcoms were rated super low and then again rated to go down to 1/4 ohm ..but the manuals give no specs for that ...

I know my 4404 was rated [email protected] bridged and I never reached a point where it was straining. my ears had all they could take . had to be more.

I would love to see what it does with a 1 ohm load on any of the models..

if you change your mind.


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## Niebur3 (Jul 11, 2008)

Great Job!!!


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## bigdwiz (Oct 7, 2010)

For those interested, I'm adding the Soundstream Reference 300 and Orion 275sx to this test as well. So far, I've done a couple of videos on the Reference 300:

*See Part 1 in HD*

or embedded below:









*See Part 2 in HD*

or embedded below:


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## Old Skewl (May 30, 2011)

I see you finally got your hands on a Reference 300. Thanks for the video!! Impressive numbers at 4Ohm stereo. Little disappointed in the Bridged wattage though. Good to know though. Keep em coming!! Curious to see how the Orion fares. BTW what voltage are these test done at? 12V is assume?!?!


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## bigdwiz (Oct 7, 2010)

Old Skewl said:


> ... BTW what voltage are these test done at? 12V is assume?!?!


My test voltage is 13.8v from my 100A Audio Authority model 978 power supply. One of my next purchases is one of those digital display volt gauges. The Orion 275sx is next up on the test, can't wait to see what it does! :snacks:


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## bigdwiz (Oct 7, 2010)

I finally got the Orion 275sx on the bench....not bad! See how it compared to the Punch 150HD, Phoenix Gold MS-275 and Soundstream Reference 300:

See the video in 1080p HD

or

embedded below:


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## Old Skewl (May 30, 2011)

You were right. Looks like the Orion is the king of the 75X2 OS hill. Nice shootout!


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## emrliquidlife (Jan 19, 2008)

Not as old, but would love to see PPI gear like the PC series. 

I don't know where you live, but if I lived near you, I'd come over with my old school amps.

Ed


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## ChrisB (Jul 3, 2008)

bigdwiz said:


> I finally got the Orion 275sx on the bench....not bad! See how it compared to the Punch 150HD, Phoenix Gold MS-275 and Soundstream Reference 300:
> 
> See the video in 1080p HD
> 
> ...


Thanks for doing this test. I've been meaning to break out my 275 SX and test it's 4 ohm bridged power, but I can't remember which box I packed it away in. When I tested mine, I managed to eek out 108 watts RMS per channel into 4 ohm dummy loads which is real close to your 112.3.


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## bigdwiz (Oct 7, 2010)

ChrisB said:


> Thanks for doing this test. I've been meaning to break out my 275 SX and test it's 4 ohm bridged power, but I can't remember which box I packed it away in. When I tested mine, I managed to eek out 108 watts RMS per channel into 4 ohm dummy loads which is real close to your 112.3.


Cool man, glad to hear some more confirmation on my testing methods! An interesting note I failed to mention in the Orion test....the "clipping" indicator (on the amp) seemed to come on before there was any actual clipping in the signal. Did you notice this in your tests? It wasn't a huge difference, but there was definitely some additional clean output before I noticed the waveform begin to flatten (on the o'scope).


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## ChrisB (Jul 3, 2008)

bigdwiz said:


> Cool man, glad to hear some more confirmation on my testing methods! An interesting note I failed to mention in the Orion test....the "clipping" indicator (on the amp) seemed to come on before there was any actual clipping in the signal. Did you notice this in your tests? It wasn't a huge difference, but there was definitely some additional clean output before I noticed the waveform begin to flatten (on the o'scope).


I noticed the same thing about the clipping indicator. From what I can tell, the clipping indicator is input based, not output power based. The reason I say that is because I had a HCCA 225 with bad JFETs that was not passing the signal, thus not amplifying, yet the clipping indicator would light up at a certain volume level.

I also noticed that the majority of my Orion amplifiers gradually clipped versus some other amplifiers that squared off immediately. In fact, here is a photo of the power test on that HCCA 225 with the bad JFETs after I replaced them:


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## bigdwiz (Oct 7, 2010)

ChrisB said:


> I noticed the same thing about the clipping indicator. From what I can tell, the clipping indicator is input based, not output power based. The reason I say that is because I had a HCCA 225 with bad JFETs that was not passing the signal, thus not amplifying, yet the clipping indicator would light up at a certain volume level.
> 
> I also noticed that the majority of my Orion amplifiers gradually clipped versus some other amplifiers that squared off immediately.


Great info, thanks for sharing!

Interesting about input vs. output clipping. I use a Yamaha RX-V670 Home Theater receiver from the early 90's and have marked it's (Pre-Amp) clipping output on the volume knob w/ tape and an arrow (pointing to the exact location - based on my 100hz test tone from my iPod). It also puts out about 3.5v RMS before clipping (Pre-Amp outs). I don't recall it getting close to this mark when I did my testing, thus my input shouldn't have been clipping? Could it possibly indicate both input and output clipping and light up at the introduction of either?

I should've mentioned, I moved from the Rockford PA-2 over to the Yammy receiver b/c the large volume control allows more precise adjustments to the volume...


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## Jonny Hotnuts (Mar 15, 2011)

I was wondering if the PG changed output by putting the impedance switch in low ohm mode when running 2 ohm mono? 

I dont know if the switch increases rail voltage but may show higher output in lower loads making it closer to the RF in output. 
(*also, I may be wrong about this but I thought PG said this amp could be run in .5)

Just wondering and cool vids. 

~JH


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## bigdwiz (Oct 7, 2010)

Jonny Hotnuts said:


> I was wondering if the PG changed output by putting the impedance switch in low ohm mode when running 2 ohm mono?
> 
> I dont know if the switch increases rail voltage but may show higher output in lower loads making it closer to the RF in output.
> (*also, I may be wrong about this but I thought PG said this amp could be run in .5)
> ...


I actually did my first round of tests w/ the low impedance mode switched on and the output at 2ohms mono was about the same. I'll see if I can find the actual output #'s I got and post them as well.

Thanks


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## envisionelec (Dec 14, 2005)

The Soundstream 300 fuse can be safely replaced with a 40A for your test purposes.


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## bigdwiz (Oct 7, 2010)

envisionelec said:


> The Soundstream 300 fuse can be safely replaced with a 40A for your test purposes.


Thanks for the tip Aaron. I should have a chance soon to retest using a 40A fuse. I think I should've done a slo-mo of the fuse popping, that was pretty cool


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## damage (Nov 25, 2008)

Great idea doing this with videos. However I have a few question/suggestions:

1) What power input voltage are these test done at? I don't see that anywhere and it does make a difference.

2) Are you testing the resistance of your resistors after each test? They would change with heating and cooling. I water cool mine so that they stay at a constant resistance.

3) 100Hz would be a far more useful frequency for most people here. That's what I test all my amps at. Could possibly do both?

4) Are you warming these amps up before testing? I burn mine in at 1/3 power and then I run the power tests.

Great videos!


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## bigdwiz (Oct 7, 2010)

damage said:


> Great idea doing this with videos. However I have a few question/suggestions:
> 
> 1) What power input voltage are these test done at? I don't see that anywhere and it does make a difference.
> 
> ...


Great questions.

1) 13.8v from my Audio Authority 978 100A power supply. I mentioned this in earlier videos, need to remember to mention it each time!

2) Yes, didn't want to bore people watching vids. I allow cool down time between ohm load tests.

3) I've used 100Hz and 1kHz, and have seen little difference in the results. I will use 40Hz and 1kHz now as I will add the SMD DD-1 to my tests to verify distortion at 1%

4) Yes, 10 mins at 30-40% power


Thanks for the comments and for keeping me honest!!


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## damage (Nov 25, 2008)

bigdwiz said:


> 2) Yes, didn't want to bore people watching vids. I allow cool down time between ohm load tests.


If you use distilled water, no cool down time would be needed.



> 3) I've used 100Hz and 1kHz, and have seen little difference in the results. I will use 40Hz and 1kHz now as I will add the SMD DD-1 to my tests to verify distortion at 1%


I've found that clipping occurs sometimes before 1% distortion is reached. But I use an oldschool heathkit. I'd be interested in what you find. I have a google doc spreadsheet of test I've done. I can share if you have a google account.


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## bigdwiz (Oct 7, 2010)

I've been wanting a THD analyzer, but they are BIG bucks, even used (I want a digital one). I think the 1% distortion detected by the DD-1 will be interesting to see vs. the waveform of the scope. It would be great to see your tests...contact me at my username at gmail.com

Great tip w/ the distilled water. I noticed an old Car Audio & Electronics mentioning using a bucket of water to keep the resistors cool. Something just doesn't seem right about submerging electronic components in water...


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## SACRAMANIAC916 (Apr 9, 2011)

great videos! subscribed.


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