# The curious phoenix gold xs2500



## razholio (Apr 15, 2008)

So I recently purchased 2 xs2500's locally for decent price (80bucks for the pair). They are in fair cosmetic condition, but I couldn't care less. Initially, the reported specs (this site and elsewhere) looked good:
2x125 4ohms
2x250 2ohms
1x500 4ohms
Great! high-density, good clean power from a respected amp model.
then I looked at the manual, and got a bit of a shock. The manual does backup the above numbers, but only for 14.4V input power. Ok, fine. The 12.5V rating for this amp? 50W! WTF? I figure the only way this could be is if the power supply is unregulated, but an increase of 150% for 1.9V? seems a tad high.

I figure either of a few things are happening:
1. I have seriously underestimated the benefits of a regulated power supply and the difference 1.9V makes.
2. the power rating at 12.5V is considerably underrated.
3. the power rating at 14.4V is considerably overrated.

I've searched and searched, and cannot find any one with any authority talk about what the actual output of this amp model would be other than something along the lines of 'will make every bit of rated power, probably more'.

Anyone know the deal behind the power ratings of this amp?
thanks, guys.


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## AAAAAAA (Oct 5, 2007)

Yeah PG's 12volt rating was a joke, underated indeed, it is meeningless.


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## rommelrommel (Apr 11, 2007)

Having seen a few of those in action, I would say that at 12v it must be doing close to the 14.4 ratings.


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## ryan s (Dec 19, 2006)

I'd say #1 and 2 are what's going on. My circa 1990 PG amp was rated for something like 50 x 2 and 180 x 1 at 4 Ohms and 12V. That's right on for 12V ratings, and it makes more in-car at 14V...something like 75 x 2 and 250 x 1 (roughly).

Some like regulated power supplies...you get the same power while sitting in your driveway as while driving. Some like unregulated...you want less draw while sitting in your driveway, playing off the battery.

Yet others want quasi-regulated that supply the juice when you really get on it and have the voltage to make it happen


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## el_chupo_ (May 27, 2007)

They are classic underrated amps. Figure on getting about the 14.4 spec, and then dont worry about it.


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## razholio (Apr 15, 2008)

thanks for all the feedback, guys. I'll go ahead and wire them up for my next rearrangement and check it out. My main concern was that I would get a drop in performance when swapping out my 75x2. As long as this xs2500 can do at least 75w at 12v, then I'm happy. 125w at 14.4v is just gravy.


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## ryan s (Dec 19, 2006)

I see you're rockin some Zeds currently...the PG should perform very similarly


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## circa40 (Jan 20, 2008)

From what I remember their 12v ratings were for IASCA. Im assuming that the lower printed ratings gave the competitor an advantage in the power class that they were competing in. 

My M100 for example is rated for 100w x 2 @ 12v, but Zed tested it to make double


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## razholio (Apr 15, 2008)

circa40 said:


> From what I remember their 12v ratings were for IASCA. Im assuming that the lower printed ratings gave the competitor an advantage in the power class that they were competing in.
> 
> My M100 for example is rated for 100w x 2 @ 12v, but Zed tested it to make double


thanks for the test numbers. I was hoping to hear something along those lines. I totally misinterpreted the IASCA notation in the PG manual, and expected that those were closer to the real values and everything else was to over-sell the performance. Good to hear it was just the opposite.


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## razholio (Apr 15, 2008)

So, I 'benched' both amps (just subjective listening) and they both sound fine except that one has a dirty gain pot and uneven output above 50% gain. I assume it's all just from the dirty pot, so I've cleaned that and will re-try later.

I opened them both up, and the 'dirty pot' one looks great inside (a bit beat-up outside). The really clean one, however, has all four power-supply caps bulging significantly on top. I've heard that bulging caps is a bad sign, but I'm not sure exactly what that means. If they're bulging, but still working, is there cause for alarm? should I just get rid of the thing?


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## razholio (Apr 15, 2008)

I just got finished testing both amps in my car. While they sound fine, there is a rather loud power-on pop from both. I swapped in a zed-made Boss of just slightly lower power rating and did not hear any power-on pop. Is this just a characteristic of these amps, or is some part of them in need of replacing and thus causing the power-on pop.


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## Hoye0017 (Mar 23, 2010)

I used to sell these and other PG amps back in those days. Very popular and did 500 bridged easy. If I remember right, most of the PG amps of that era that we sold had some sort of strange sensitivity to any variance of potential to ground on the RCA shield (grounded) connection. There were different instances in which we had to solder a grounded wire to the outer shield to eliminate pops and other noise. The other thing I remember about the xs2500's that was kind of peculiar was their DEMAND for 4 ga. Every single 2500 we sold that had a 8 ga battery line would fry in a few weeks. Every 4 ga installation never had a problem. Sounds weird I know but true. The only explanation I could think of was that something in the rail voltage regulation didn't like the voltage drop at peak current demands from 8 ga. Are you running these on subs or mids/highs?


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## razholio (Apr 15, 2008)

Hoye0017: I tested both amps running mids from 100-3500hz. They are getting the filtered output from another amp that does tweeter duty. That amp is a zed gladius which I believe uses a floating ground on the line-level side of the preamp section.

That is odd on the 4ga requirement. That would have to be contingent upon the amp being driven to high enough levels to demand that kind of power, though. What in the amp would fry from undervoltage? I've heard that undervoltage is the most dangerous thing for an amp, but have never understood why. The only thing I can come up with is that the lower voltage would require the power-supply to draw more current, but I thought that would only happen with a regulated power supply...


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## [email protected] (Jun 12, 2008)

If the caps are bulging they prob need to replaced, if they are leaking or do leak it an catch fire. The caps are cheap and easy to put in if you can solder yourself. You can look closely and see if they are leaking but sometimes there is only alittle under the caps that you can see yet.

You might want to post on PhoenixPhorum and see what they say about the popping and scratchyness you are experiencing. Alot of knowledgeable people over there about PG products


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## razholio (Apr 15, 2008)

thanks for the tip, BeatsDownLow. I'll look into replacing the caps, and hitting up the phoenixphorum. Any favorite place to order caps from? I don't believe in snake-oil...


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## Hoye0017 (Mar 23, 2010)

razholio said:


> Hoye0017: I tested both amps running mids from 100-3500hz. They are getting the filtered output from another amp that does tweeter duty. That amp is a zed gladius which I believe uses a floating ground on the line-level side of the preamp section.
> 
> That is odd on the 4ga requirement. That would have to be contingent upon the amp being driven to high enough levels to demand that kind of power, though. What in the amp would fry from undervoltage? I've heard that undervoltage is the most dangerous thing for an amp, but have never understood why. The only thing I can come up with is that the lower voltage would require the power-supply to draw more current, but I thought that would only happen with a regulated power supply...


Yeah that's the part where my explanation kind of falls apart. I never did come up with a definite explanation for why 8 ga doesn't work. That said, We really used these solely as bridged sub amps. if you're using them for mids, I think you'll be alright.


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## [email protected] (Jun 12, 2008)

razholio said:


> thanks for the tip, BeatsDownLow. I'll look into replacing the caps, and hitting up the phoenixphorum. Any favorite place to order caps from? I don't believe in snake-oil...


Digikey or Mouser


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## coefamily (Sep 24, 2009)

I recently installed one of these to a 2ohm mono sub, which it is rated for. I keep blowing the fuse, Im gonna use 4g power line and see what happens. Thanks for the tip.
In regards to the underVoltage problem. 
An amp, wether regulated or not will try and produce its power (watts). As Voltage decreases, Current Increases (an Inverse Proportion). Therefore your fuse might pop. 
I'll let you know if the 4g trick works for me.


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## razholio (Apr 15, 2008)

thanks for all the help on this, guys. I went ahead and hooked up the XS2500 with the nice-looking caps and it sounds fine to my ears. There is something strange, though. After about 1hr of moderate listening, the amp was rather warm to the touch (definiitely over 100F on the heatsink) and the ambient temp in the car couldn't have been more than 60F this morning while it was on. For comparison's sake, a similar amp (zed-made boss), in the very same place and with the same load, never *ever* got even remotely warm to the touch. This amp is currently driving two 4ohm loads, and I plan to drop that to 2ohm loads in the near future. I don't think I dare do that with this amp considering how warm it's getting. Is there something wrong with this thing or do some amps just run this hot?


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## helpmeplease (Oct 6, 2012)

razholio said:


> thanks for all the help on this, guys. I went ahead and hooked up the XS2500 with the nice-looking caps and it sounds fine to my ears. There is something strange, though. After about 1hr of moderate listening, the amp was rather warm to the touch (definiitely over 100F on the heatsink) and the ambient temp in the car couldn't have been more than 60F this morning while it was on. For comparison's sake, a similar amp (zed-made boss), in the very same place and with the same load, never *ever* got even remotely warm to the touch. This amp is currently driving two 4ohm loads, and I plan to drop that to 2ohm loads in the near future. I don't think I dare do that with this amp considering how warm it's getting. Is there something wrong with this thing or do some amps just run this hot?


I was running mine in my room and it got real warm by just being on. I put 2 120mm fans on 5v on it. Did the trick, and silent. 

There is this weird coat of bed liner or something over the metal. That cant be good for heat dissipation. Im tempted to strip it and polish it.


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## 82cj8 (Jan 21, 2011)

I have owned xs2300,2500 ,4600, 4300.I still have the 2300 and they do get hot.Good clean power though and my birth sheet on the xs2300 was 1x328rms at 4ohms ,but I ran it at 3ohms on a 12w6v1.I did manage to overheat the 4300 once while on a 1hr drive playing Metallica and justice for all cd at full volume the entire way.


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## ATOMICTECH62 (Jan 24, 2009)

helpmeplease said:


> I was running mine in my room and it got real warm by just being on. I put 2 120mm fans on 5v on it. Did the trick, and silent.
> 
> There is this weird coat of bed liner or something over the metal. That cant be good for heat dissipation. Im tempted to strip it and polish it.


 The idle bias needs adjusted.Every one of these XS series Ive seen has this problem.It eventually leads to their death.
As time goes by they tend to drift little by little.Sometimes one channel will drift the other way and need increased.
If it gets warm in under 10 minutes with no load or signal it needs attention.


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