Phoenix Gold Phorum

For those of you who were not aware, the MS2250TA is a more limited output version of the original MS2250. Although the MS2250TA is rated at 250W RMS by two into 4 ohm loads, its real power is only 220W RMS by 2 into 4 ohm loads.

I purchased a mint (maybe even new) MS1000TA a few years back, and when I found out it would only do 220W a channel, I was quite unhappy. So, I went about upgrading the amp to perform as it should, like the original.

About 40 parts per board need to be changed, and new transformers must be wound.

In the end, I ended up with a wee bit more power than the original. Here are the power figures…

MS2250TA = 220W a channel at 4 ohms

MS2250 original = 360W a channel at 4 ohms

My MS2250TA modded = 380W a channel at 4 ohms

This amps design is so versatile, one can go even higher. I had plans in the works for a 400W x 2 into 8 ohm loads, just for running home speakers in my car.

Here are some photos of the project…

Hey Doc

how much would this cost , I may be getting a MS1k soon and would maybe like to send it to you before I collect it, for the "upgrade"

I have to sit down and run the numbers to figure out what I have into each of these mods.

Last I remember it took me at least 2 hours per transformer to rewind them. I go the extra mile to make the windings as tight as possible, which keeps them from vibrating under load.

The mod would not be cheap, but I am sure I can make it “reasonable”.

ok, please if you can work it out , with the BB opamps and what ever else u think she may need to sound better.

I know C has that nice blue and silver cable too which looks so in place in the MS1k.

Did you say 400x2 at 8 ohms?

stipud wrote:Did you say 400x2 at 8 ohms?

Yep, with 80V rails if I remember.

Vlad and I were working out the details. Remember Vlad?

I should probably provide a bit of background as to what this entails, so everyone can get a grasp as what has to happen.

1) Transformers carefully removed to prevent any damage to the circuit board. These transformers are so large, they wick a lot of heat away, so removing them can be pretty time consuming without a really good soldering iron.

2) Transformers unwound as the internal cores are used to wind the new transformers onto.

3) Addition of 4 more Zobel filters to the power supply section of the amp. One Zobel exists for each leg of the transformer. The MS2250TA has two primary legs, but the original used 4. More legs means more copper cross sectional area, which means more current capability.

4) Replacement of new modified transformers.

5) Change to PWM feedback loop for higher voltage. Even though PG amps are unregulated, they are highly regulated internally. This means their rails are a ratio of their input voltage, but the amp will do everything it can to maintain this ratio. If you replace the transformers, but not the PWM feedback to the SG3525 controller, the amp will output no more power than before, but will become less efficient, as its power supply will not be optimal for the winding ratio and loading.

6) Change to op-amp 15V supply circuit. If you do not change the resistors feeding the zanier based 15V op-amp supply, the resistors will fry.

7) Change to op-amp gain stages. If you do not update the feedback circuits for the op-amps on the preamp side of the amp, the preamp will clip prior to reaching max output voltage on the amp. A few parts changed here gain you several volts of output.

8 ) Rebias the amp if need be. You should not have to rebias the amp, but I suppose you could if you chose to. Since PG amps are unregulated, they are designed to work with variable rail voltages. When I significantly increased the rail voltage of both my boards, the bias point did not change. This is pretty handy for anyone attempting to perform this mod, as it makes it one less issue to worry about.

Here is a shot of the amp in my car. It worked great for six months until a guy spun out in front of me and totaled my car. Then I became so frustrated at the loss of my install I sold everything.

Eric D wrote:Vlad and I were working out the details. Remember Vlad?

Yep. Who could forget his three floor install in the back of a del sol.

I wonder what he's up to now? Quick google search found him on the Exile forum...

http://www.exileaudio.com/forum/profile ... ofile&u=15

can an ms2125 be modded to ms2250 spec? i'm guessing anything is possible?

One other thing I did to my amp, which I don’t suggest for everyone, is I bypassed all preamp capacitors in the signal path.

This eliminated the low frequency roll off of the amp at around 20Hz, and would allow it to pass frequencies down to 0Hz, or in other words DC.

marko wrote:can an ms2125 be modded to ms2250 spec? i'm guessing anything is possible?

Any “full sized” MS amp can be made into another.

So…

MPS2500
MS2125
MS2250TA
MAC500
MS2125TA

Can all be made into MS2250 originals, or you can go backwards from a MS2250 to those models.

It kind of sucks for the consumer, as a MS2250TA costs no more to manufacture than a MS2125 or MPS2500, yet PG could charge much more for them. At least with the MS2250 original you get a fan shroud.

This is also true of the MS275, MPS2240, and MAC200.

It should also be true of the MS250, and MPS2220.

Well considering these amps are by mo means cheap , with a RRP of well over $1000 , I would not expect the upgrade to be too cheap , but help a brother out, I mean I would need to do this twice

stipud wrote:

Eric D wrote:Vlad and I were working out the details. Remember Vlad?

Yep. Who could forget his three floor install in the back of a del sol.

I wonder what he's up to now? Quick google search found him on the Exile forum...

http://www.exileaudio.com/forum/profile ... ofile&u=15

although all his postes are dated 2005

i would love to have the works done on my 2 ms2125's the whole hog to original ms2250 spec but the cost would be massive i guess

I am planning on changing my MS2125 into a MS2250, so when complete, I will have a better grasp for the cost involved.

The parts do not amount to a whole lot, but the hours of labor are where it adds up.

In the case of the MS2125, it needs all new power supply MOSFETs, and new output transistors which can take the higher voltage. These items start adding up, considering each is probably $3 or more. The MS2125 also needs new rail caps which I think are $5 each.

All told, there is probably more than $100 additional in parts alone for the MS2125 to MS2250 changeover.

But, keep in mind this gets you an original MS2250 in function (not cosmetics), which is very rare these days.

you'll have to see how much labour it takes to do your ms2125 then! i already have 2 original ms2250's and having 4 of same spec would be crazy especially if i can get some very special shrouds that i have in the pipeline

And this is why I love this phorum and the guys in it, also why I love this product ......

Please doc as and when u gett he time , let us know , I will be paying for myt MS1k in Dec and can get it shipped to you and then u could get it back to my seller as he has 2 other amps I need to have the courier collect , but only in Feb next year

shaheen wrote:ok, please if you can work it out , with the BB opamps and what ever else u think she may need to sound better.

I know C has that nice blue and silver cable too which looks so in place in the MS1k.

Shakeen please check with bdubs as i do not have the original blue and silver cable from PG. He has some of that left for his amps. A similar wire is available from several of the wire suppliers but it will not say Phoenix Gold on the cable. Just a FYI my friend...C

marko wrote:you'll have to see how much labour it takes to do your ms2125 then! i already have 2 original ms2250's and having 4 of same spec would be crazy especially if i can get some very special shrouds that i have in the pipeline

DOH! Man, I would love to just have 1 2250 with a fan shroud!

soth wrote:

marko wrote:you'll have to see how much labour it takes to do your ms2125 then! i already have 2 original ms2250's and having 4 of same spec would be crazy especially if i can get some very special shrouds that i have in the pipeline

DOH! Man, I would love to just have 1 2250 with a fan shroud!

the 2 shrouds that will be for the ms2125's arn't the same as the ms2250 shrouds, i'm waiting on pics for them but from the conversation i had with someone who was a pg dealer back all i can say is i didn't know they even existed!!

Eric D wrote: MAC500

Never heard. What is it?

It is either a MS2250TA, or a slightly different voltage amp than a MS2250TA.

1moreamp wrote:

shaheen wrote:ok, please if you can work it out , with the BB opamps and what ever else u think she may need to sound better.

I know C has that nice blue and silver cable too which looks so in place in the MS1k.

Shakeen please check with bdubs as i do not have the original blue and silver cable from PG. He has some of that left for his amps. A similar wire is available from several of the wire suppliers but it will not say Phoenix Gold on the cable. Just a FYI my friend...C

Hey Cecil

I am not too fussed if it is not the original PG cable , I found the Directed twisted is quite nice too and so is the stinger, besides I remember seeing a roll of the Zeropoint cable at a dealer I went to , I asked him if he still has it and if he does I will have it sent to you or Doc from SA.

What I do have is the ZP boots, the original PG ones.

Eric D wrote:For those of you who were not aware, the MS2250TA is a more limited output version of the original MS2250. Although the MS2250TA is rated at 250W RMS by two into 4 ohm loads, its real power is only 220W RMS by 2 into 4 ohm loads.

About 40 parts per board need to be changed, and new transformers must be wound.

MS2250TA = 220W a channel at 4 ohms

MS2250 original = 360W a channel at 4 ohms

My MS2250TA modded = 380W a channel at 4 ohms

OH NO!!!!!

220W??? And I was hoping that my new MS1000ta would rock the world out of my 2x18" CV Strokers..... Why did not I know this before I got the MS1K sent to my house

Is it possible to buy the needed parts from you Eric (ofcourse price included labour), so I can have theese parts installed here in Norway?? Since the shipping of a MS1000 overseas is quite expensive.

And yes, IF your upgrade has been done, what about the original parts from the MS1000ta? Would they be of any benefit into an MS2125 for example? Or are they just "trash" ??

Pedi, that is just 4 ohm wattage. I assume at 2 ohms the MS1000TA would probably do just as much damage as an MS1000 at 4 ohms.