Phoenix Gold Phorum

Well, hello, and thanks fer havin me; it's my first post over here at phoenixphorum!

So, I'm looking at buying an amp from my neighbor, he's had it 10 years or so, and it's been sitting in his attic for the last 5 or 6. First I need to know what it is (model #) so I can figure out power rating, stability, etc before I can figure out if I want it/can use it, and/or how much to try an talk him down to $$.
It's a pheonix gold, and a big'n at that.
Apparently, it was painted to match the vehicle, and someone replaced the metal cover with plexiglass.

So, what is it?

i'll check it out........

interestingfellow wrote:Well, hello, and thanks fer havin me; it's my first post over here at phoenixphorum!

So, I'm looking at buying an amp from my neighbor, he's had it 10 years or so, and it's been sitting in his attic for the last 5 or 6. First I need to know what it is (model #) so I can figure out power rating, stability, etc before I can figure out if I want it/can use it, and/or how much to try an talk him down to $$.
It's a pheonix gold, and a big'n at that.
Apparently, it was painted to match the vehicle, and someone replaced the metal cover with plexiglass.

So, what is it?

looks to be ms-2125 i think

Per the end plates it is an MPS2500 but that is not definitive in itself. What is the serial number on the board? It will tell you what it is. The first numbers will be either 21 for an MS2125, 22 for an MS2250, or 25 for the afore mentioned MPS2500. They are all bad ass. It will require some much needed maintenance before you put it to use. Input capacitors need to be changed as those look to be original. This will prevent it and your car from burning. Not to scare you, just needs maintenance for another 20 years of reliable service.

If you decide against the purchase someone here will gladly pick it up.

Welcome to the forum!

Hello earthlings...

is he lookin to sell it?

Well, thank you for having me, an thank you for the quick replies!
ok, so, what you see is what I've got, so if there is a serial number on the board, someone will have to give me directions to get to it.

And, I am asking ya'll after all, but I'm gonna go with the 2125, as i quadroople taked as to whether or not money-b had accidentally reposted my own pic! Just a guess though.

And, why would I want to replace the caps (technically speaking)? I'm a novice at this, so I apologize for asking noob questions. My understanding stops at a block diagram of an amp's guts, and as to hook them up (somewhat) properly

Yes and no about him selling it. he's looking to sell it, and I'm looking to settle a small debt he has with me. He also has a zx250 that's also 15 years old, but was only used for a year and then stored.....

And finally, what is the local price in hand on an operational 2125 (not fleabay or some online refurbisher, but some dude selling one) or zx250?

Thanks again guys!

i found the pic....it's an old ampguts website picture....didn't copy yours,lol.

OOOOOOOOOOOOOOOOOOOOOOH!!!!
After some more googling (on the 2125), I saw the different things printed on the case, and upon further inspection, I can vaguely read what's under the car paint!!!!!!
Drum roll please........It's an MPS-2500!!!!!!

I found the manual.
Now, don't cut my nads off. I'm not looking to win any competitions here. I have a 90 Astro that I'm....I dunno what to call it. I'm spiffin it up a bit, but not for anyone but me. I plan on throwing 2 15's under the backseat (the box will be the seat mount and replace the oem supports). I'm totally on less than a shoestring budget. I'm looking at two boss cx15dvc subs and had been looking at an nx1800.1 amp. I know they aren't the best speakers, but they are in my price range ($50/ea) and are still 15's, so they WILL bump; not as much as an MTX 15 DVC, but still. anyway, the nx1800 would throw out the 900w the speakers are rated for (450/coil). This amp appears to be rated for 500w rms when bridged @2ohms. True? I've read that the PG amps are generally advertised "underrated". the 2500 is not 1ohm stable is it? That just doesn't seem like much power for this huge beast????

Suggestions? (that don't require more than a couple hundred bucks for the subs/amp)


Also, there is a little grease on the board down by the small caps down by the three toroid coils. I can only assume one or more of the caps have ruptured during storage???

Changing the caps is standard on these old amps as they liked to leak which if you look closely at yours there appears to be some gunk around the bottom of caps on the board. If you don't change caps and they are leaking your amp could go up in fire then it's toast.
It would be worth approx $200 and up in good working condition if it needs caps which I think it does take that into consideration with what you pay for it. Also worth More to some if it wasn't painted. I just sold a zx250 for $150
Serial number is located at the back of the amp near the top of your caps in your pic you can kinda see the # hiding behind the caps. Top left in pic.
Depending on price I would be interested in buying this as I already have caps to swap in it, And it would also add to my collection. The purple really isn't a huge deal I have a friend that is really good at uncovering original paint without wrecking it.

Last time I tried to post it said a mod had to approve, so if it posts and/or this post gets held and posted, then sorry.

Turns out it's an MPS2500. The manual might be good to wipe my ace with. It says its 505wrms bridged at 2ohm, and that it's 1/4ohm stable? Look:



So, what's a 2500 rated for. I've googled it, but dern there's a lot of trash and user manual web sites out there that make it hard to find the truth! Bass tards!

Also, I plan on replacing the caps as you are correct; there is grease on the board around the smaller caps. Should I replace all of them (big blues too)? Can I get "better" caps? Where should I get'm? (I usually get components for various projects, as needed, from digikey, allelctronics, and the RadioCrack). My knowledge of the guts of amps is limited mostly to block diagrams, although I understand a bit about transistors, fets, toroids, and the like, as well as having moderate through hole soldering experience, and limited smt experience.

For now, I'm gonna try and throw this amp on two Boss CX154DVC 15" subs. 900wrms max/each (450/coil). I'm trying to figure out how much power this amp will push with 2 channels @2ohms, or 1 channel @1ohm (if it will support 1 ohm)?

I know the Boss subs could be seen as horse hockey, but I'm on less than a shoe string budget, and I'm trying to do a whole lot to my Astro, all at once, without pissing off my wife. Plus, it's a 1990, so..... no need to blow more on the stereo than the van is worth. But it's soo basic (it was a cargo van, that I used as a work van for a year or so) and Astro's are a dime a dozen. I'm doing my own carpet, dying all the hard vinyl interior trim, re-upholstering the seats, etc. I'm not goin for competitions, just personal satisfaction. I'm gonna build a box for those 15's to replace the rear bench seat's support brackets. I'll post pics later when i'm farther along. Actually, I have a donor Astro I picked up with a good 4.3 and no tranny or seats, for $200. I'm gonna get $400 for it as scrap, when I've swapped all the parts I want off it (front end is dingless, my slider needed to be replaced, runnerboards, all the interior trim, Al rims, etc). Anyway, a better set of subs can always be thrown in later.

I can't wait to hear some more from ya'll, and THANK YOU!

welcome to the the phorum man

Don't replace the blue caps and the other caps you can get from digikey part # 493-1543-ND is the caps we all use here and I think all amps use those for replacement caps Eric or someone that knows for sure will chime in if I am wrong. On the manual you posted the ratings to the right under MPS2500 are correct for your amp.

Alright.... cool, and thanks!
SO: is it indeed 1/4ohm (0.25Ohm) stable as the manual says on the right side of the manual page (which also says that it puts out 2chX50watts....)?

let's apply ohm's law then:
for bridged down to 1 channel:
2ohm=500wrms
1ohm=1000wrms
0.5ohm=2000wrms
0.25ohm=4000wrms

Yeah?
(I know the formula is right, the question is in real world application; I've never heard of 1/4ohm stable, but then again, I'm also the guy looking at Boss instead of PG,RF,or MTX)

ohms doesn't apply to this amp or very many of PG amps as they are current limited to ensure it doesn't start on fire. It is 1/4 stable in stereo not mono but it won't double it's power when you cut the load in half. Orion old school HCCA was 1/4 ohm stable too, back in the days off cheater amps.

ok!
so, on this amp, 2ch stereo@2ohm=505wrms each channel (as per the manual)
stupid question: what about peak?

here are the subs I'm looking at http://www.bossaudio.com/main/1172# (the 15's)
Think the amp will drive them (or rather, overdrive)? fry'm?

It kind of bothers me that tech support couldn't provide me with the t/s numbers.... They told me it had the same numbers as the 12".... yeah, ok, a 12 and 15 with different cones, coils, and sizes are gonna have the same T/S numbers.

Anyone have a suggestion for a set of 15s (or even 12s) for this amp? If I can jew my neighbor outta this amp for the debt he owes me, and fix it for <$50, then I can afford about $150 for a couple subs. I have plenty of room (I have up to or a little over 48"x24"x10" (6-2/3 ft3)


Thanks again!

interestingfellow wrote:ok!
so, on this amp, 2ch stereo@2ohm=505wrms each channel (as per the manual)
stupid question: what about peak?

here are the subs I'm looking at http://www.bossaudio.com/main/1172# (the 15's)
Think the amp will drive them (or rather, overdrive)? fry'm?

It kind of bothers me that tech support couldn't provide me with the t/s numbers.... They told me it had the same numbers as the 12".... yeah, ok, a 12 and 15 with different cones, coils, and sizes are gonna have the same T/S numbers.

Anyone have a suggestion for a set of 15s (or even 12s) for this amp? If I can jew my neighbor outta this amp for the debt he owes me, and fix it for <$50, then I can afford about $150 for a couple subs. I have plenty of room (I have up to or a little over 48"x24"x10" (6-2/3 ft3)


Thanks again!

Please don't buy the Boss Subs... complete waste of money & time, especially if your building a enclosure.. Atleast buy a good brand name & something that is not garbage after your done using it.. Buy TWO JL Audio 13w1v2 subs & build a enclosure... it will be plenty!

There is 6 brand new TI 12"s and some 10"s on ebay or you could look for some RSDC 12" on ebay too they pop up now and then. All are good sub choices.

IT"S MINE!!!!!!!!!!!!!!!!!!!

Traded him outright, debt for the amp, today.

I also called tech support. Because it's a cheater amp (and advertised as 2x50wrms @4ohms), there was quite a discussion about the power output of the amp. For my purposes, we came to the conclusion that I should treat the amp as 2chx500wrms 2ohms, or 1chx1000wrms @1ohm. Also, Earnie #133, had suggested some Interfire 12's or 15's for my application. I'm comparing price, performance, and availability of the TI, JBL, and Interfire subs, now. Humble opinions?

So, I basically got the MPS-2500 for about $50, and for another $20, I can replace the caps. Awesome. Anything else I should do to or check on the amp?

You guys have been a ton of help, THANK YOU!

EDIT: Uhhh, what should I search for the TI or RSDC subs (what are they)?

Two questions for you...

1) What is on the board which I drew an arrow too in your photo?

2) What is the voltage rating on the big blue caps?

1. a blade of dried out grass that floated in when the plexi wasn't in place, during storage (the plexi was just sitting there, not screwed down)
2. 35v (why do you ask?)

35V means it is a MPS2500. Just one more way to tell them apart.

This board is used in several PG amps, the MPS2500, MS2125, MS2125TA, MAC500/MS2250TA, and the MS2250 (original).

I have never seen a MS2125TA, so I can't make any claims on it, but the following is true...

MPS2500 = 35V
MS2125 (and probably the TA version) = 50V
MAC500/MS2250TA and MS2250 (original) = 63V

There is no way to tell a MAC500/MS2250TA apart other than the chassis they are mounted in, but you can tell them from the original MS2250 by looking at their transformers.

I am pretty confident the MS2125 and MS2125TA are identical with identical parts. But again, having never seen a MS2125TA in person I don't know for sure.

well, just ordered my power caps; right under $20.

so, rinse down the board with no residue electronic cleaner (to get off the cap oil) and go ahead and swap'm?

And to Eric D; mighty fine eye you have there, bra!

http://cgi.ebay.com/BNIB-OLD-SCHOOL-PHO ... 45f8725f3c
http://cgi.ebay.com/Phoenix-Gold-Compet ... 3cb4d08b3b
these are both good subs and the rsdc 12"s pop up once in a while brand new still.

don't go crazy with the cleaner. Get the areas that you need to clean with it and the rest will do fine with a light rubbing/cleaning. I was suprised how a dry que-tip cleaned the gold up really well with out any cleaners needed.