MS-2125 questions

DDS · Post by **DDS** » Tue Mar 18, 2008 10:46 pm

High!
I'm going to purchase MS-2125TA, and I should like to ask few questions about it.
Is MS-2125TA a well designed and manufactured amp as the old MS-2125? Does it worth buying it? Or an old MS-2125 is much better than MS-2125TA?
My head unit is Eclipse CD8053 with 8V pre-out. MS-2125 has the input sensitivity 0,2V to 2V. Will the amp accept the 8V rca input voltage?

Best regards,
Dmitry.

1moreamp · Post by **1moreamp** » Tue Mar 18, 2008 11:20 pm

Welcome to the forum...

ALL MS amps are worth having....the 2125 TA is still fairly the exact same amp as the 2125 original.

Now the TAs were later models, and all TAs seem to have some power supply differences BUT these differences will be less pronounced in the 2125 because the 2125 was such a perfect amp design. With sink to power ratio is in its sweet spot.
Unlike the larger 2250, the original 2250 had so much power beyond its base rating it was prone to overheating, so they made shrouds. The TAs addressed this issue with some redesign work in the power supply so the amp would run cooler.
Since the original 2125 did not have these issues < again because of its balanced design > I don't think you will be too disappointed, if you can even hear the difference at all.
The power curves are different for each of these amps, most people can't hear this difference and you will need SPL measuring tools to see it in most cases.

If you out for RAW SPL power look for a older 2125, if your SQ oriented a TA will do fine just ask around here on the forum. There are dozens of both of these amps owned and represented here by many of the forum members...

The 2125 will only need 2 volts to deliver full power so your super deck will be able to overdrive the amp by a fair margin. May I suggest a simple resistor type divider network, consisting of two 5 K ohm resistors for each RCA cable end at the amp. A simple 2 to 1 divider.

Another way is to alter the gain of the front end of the 2125, by changing a couple resistors internal to the amp to lower the input gain to match your HU. But this is best done by someone well versed in these amps. The simpler method is the resistor divider on the RCAs < no internal work required, you can add this to the RCA connection end adapter yourself >

Post by **Wakeup** » Tue Mar 18, 2008 11:27 pm

Welcome to the forums DDS!

I dont know the differences and not as well versed in the intricacies of the amps. So you are in good hands w/ 1moreamp! as well as some of the others here. Again Welcome! you've come to the right place!

DDS · Post by **DDS** » Wed Mar 19, 2008 12:05 am

Thank you very much for your support. I forgot to introduce myself

My name is Dmitry, 27 y.o. I am from Russia. For now I have one amp Sinfoni 90.2 and a two-way speaker system AD MM. And my head-unit, not so expensive, but pretty rare CD-tuner Eclipse CD-8053.
I'm looking for great sound quality, not for raw power.
It seems to me I found a perfect amp for midbass speakers - PG MS-2125. As for Sinfoni, it will drive tweeters, until I add some midrange speakers.
And few questions again.))
What it will be, if I just connect PG to Eclipse, without any adapters? Will I have distorted sound, or the amp will be damaged, or something else will happen?
What about above mentioned divider network? Should its presence colour or distort the sound of my system? Or it will be absolutely neutral to sound?
P.S. Sorry for my English.

Pedi · Post by **Pedi** » Wed Mar 19, 2008 1:19 am

Hello Dmitry, a great velcome to the first (I believe) user from Russia.. Your English is very good, no doubt.

I wonder about one thing. PG is not too known in Norway, but I assume that it is even more rare in Russia?

Lucky for you, there exist Ebay.

I love the MS2125 myself, I bought my first in 1992 - and still have it...

DDS · Post by **DDS** » Wed Mar 19, 2008 1:46 am

Pedi wrote:Hello Dmitry, a great velcome to the first (I believe) user from Russia.. Your English is very good, no doubt.

I wonder about one thing. PG is not too known in Norway, but I assume that it is even more rare in Russia?

Lucky for you, there exist Ebay.

I love the MS2125 myself, I bought my first in 1992 - and still have it...

New PG is not a rare thing in Russia. As for an old PG amps... You know, there are such people - audiophiles. They exist in Russia also

As you know, many Russian enthusiasts were champions in different worldwide SQ competitions. They are in continuous (and I must say - endless) searching of the perfect sound. So they change their components very often, trying to get closer to their ideals. That is why oldschool PG amps, as much as PPI, Zapco, PowerAmper, and others are famous among a number of audiophiles.

nico boom · Post by **nico boom** » Wed Mar 19, 2008 5:08 am

Hi DDS; WELCOME!
Nice to hear there are even people in Russia who know real quality...MS-SERIES!!

I would buy that MS2125TA for sure..... but then again, I would buy ANY MS2125 for sure...

Your questions were already answered by Cecil; there's no need to add something to his technical support as usual.
[Happy to see you again C...]
Nice to have you with us Dmitry; enjoy the PG-atmosphere.
nico

DDS · Post by **DDS** » Wed Mar 19, 2008 7:37 am

More questions

I saw different pictures of MS2125.

Are there two different designs of MS2125 with L&R inputs and outputs situated distantly from each other (L far from R) and with the ones situated close to each other (L near R, for example, picture of MS2125 in old PG FAQ). Both types are shown at Ampguts.realmsofexcursion website.
What is it? Are there two different designs of MS2125, symmetric dual-mono and not?

1moreamp · Post by **1moreamp** » Wed Mar 19, 2008 9:49 am

The differences are purely artistic in nature, so don't let the two different layouts throw you a curve. Its still all the same hookups.

The divider network consists of two 5 Kilo-ohm resistors. It places a constant 10 Kilo-Ohm load on your head unit, but only allows 1/2 of that signal level to your amp.
This allows you to use the 8 volt output of your deck, but at the input RCAs the amp will only see 4 volts max. Due to ohms law the voltage across both resistors will be equal and balanced so if you connect the center connection of the two resistors to the RCA tip you will get 1/2 the signal and since the resistors are considered to to be "passive" in nature the coloration should be minimal.
Check this out with some of your local tech people, i am sure they will understand. I do this to a lot of the old school amps. You still get the lower noise floor of a 8 volt deck, and the amp still gets a signal that will only overdrive the amp to +3 DB's max, instead of +6 DB's or more without the resistor network.
Plus it only costs about $1.00 US to fix this, less if you look around for best pricing of the resistors.
The other option is to reduce the gain of one of the op-amps stages in the front-end of the amp.
Another option is to bypass all the Op-amps in the front-end, this will also allow you to run full signal level. But here again your tampering with the amps design.

Again welcome to the Phoenix Forum! I hope we have been helpful to your need.....

Pedi · Post by **Pedi** » Wed Mar 19, 2008 9:56 am

DDS wrote:More questions
I saw different pictures of MS2125. Are there two different designs of MS2125 with L&R inputs and outputs situated distantly from each other (L far from R) and with the ones situated close to each other (L near R, for example, picture of MS2125 in old PG FAQ). Both types are shown at Ampguts.realmsofexcursion website.
What is it? Are there two different designs of MS2125, symmetric dual-mono and not?

I guess there is also needed to mention that the boards are (for non-techs like me) delivered in different versions/revisions... That is listed on the board what Rev it is...

Post by **mhyde71** » Wed Mar 19, 2008 6:40 pm

I may be mistaken.. and other may know better than I ... oh and correct me if I'm wrong.. I think the two differences that DDS is referring to is the difference between the 2125 and the 2125TA. Whereas where the left and right sp outs are close to eachother are the 2125 and the where they are further apart is the 2125TA. Again might be wrong and maybe DDS could correct me as well if that is not what he was referring to, but I believe it is. and that is the difference between the speaker L+R Being close and/or far apart, no???

M

Pedi · Post by **Pedi** » Wed Mar 19, 2008 6:53 pm

@mhyde71: please take a look at this pic, diplaying Rev B and C-boards:

Post by **mhyde71** » Wed Mar 19, 2008 7:34 pm

interesting.. i'mma have to go look at mine now and see what I got going on... think it is like the middle joint you got there... I dont recall seeing my wires go down one side like that.. might be mistaken though... However/But, i didnt see that on ampguts like DDS pointed out in his inquiry. I may not be looking right, and I worked a double today on the road looking through a windshied all day...
definately Neat though! Any disadvantages or advantages to either of them?

DDS · Post by **DDS** » Wed Mar 19, 2008 7:58 pm

Dear guys!
Thank you very much for your help. You answered all my questions.

As for the divider network, I understand I will need it. Dear Cecil, could you send me a picture (schematic) of the network?
As for different versions, Pedi, thanks for your picture, I realised that both versions are dual-mono, but with different displacement of rca's and sp. outs. By the way, Pedi, I see you have Mitsubishi Lancer, Evo, if I'm not mistaken.

I have Mitsubishi Lancer too, but not Evo.

Again, thank evryone for your replies.

I am very glad I came here.

1moreamp · Post by **1moreamp** » Wed Mar 19, 2008 9:38 pm

Here you go, a simple divider....

PS Ohm's Law says this works. Any signal will drop across both resistors evenly, so the split in the middle gives a center tap so to speak that is exactly 1/2 the total drop across both resistors. " A simple divider network"

1moreamp · Post by **1moreamp** » Wed Mar 19, 2008 10:36 pm

Hey Tom, you might want to cut and paste the above post to the "How To FAQ' area. labeled, How to deal with 8 volt output and line driver levels while using Old School amps rated for 2 volts input.

It solves the line driver and 8 volt HU output mismatch issue for ALL Old School 2 volt amps. This is also similar to a PPI engineered solution I got from them years ago.

It also can have different resistors give different ratio's.
Like 7.5 K ohm ( R1) and 2.5 K ohm (R2) will give a 2 volt out for a 8 volt in, a 4 to 1 divider ratio.

If the load values represent a Impedance mismatch issue you can also do a divider based on a 30K ohm and 10K ohm resistor setup. 4 to 1 ratio high impedance.

I based the above on a simple 10K ohm input impedance of the amp. Any line driver will have a output impedance of 600 ohms or less in most cases and the 10K will not represent a load issue, so SQ should not be compromised.
Most car amps use as many resistors in their input section of the amps so here again I really don't think there will be any noticeable SQ issues.

The end result of this economical solution is the safe usage of Old School amps with new HU's and line drivers. This also allows for all the advantages of those high output HU's and LD's while still using some of the finest amps ever made without overdriving them till they let the smoke out, or your tweeter blow smoke rings from clipping.

DDS · Post by **DDS** » Wed Mar 19, 2008 11:32 pm

mhyde71 wrote:However/But, i didnt see that on ampguts like DDS pointed out in his inquiry. I may not be looking right, and I worked a double today on the road looking through a windshied all day...
definately Neat though!

Look for the pics of MS-2125. Most pics (inside view) shows symmetric layout of cables inside the amp. But the last pic (side view, terminal panel) shows L&R inputs and outputs placed close together.

brenzbmr@sb · Post by **brenzbmr@sb** » Thu Mar 20, 2008 12:36 am

Pedi wrote:@mhyde71: please take a look at this pic, diplaying Rev B and C-boards:

actually those are all rev b boards. late model b boards came with the
newer front end.

Pedi · Post by **Pedi** » Thu Mar 20, 2008 1:34 am

brenzbmr@sb wrote: actually those are all rev b boards. late model b boards came with the
newer front end.

What? Seriously?

- Just another thing I did not know...

But normally the C-boards have the new end.. right?

Pedi · Post by **Pedi** » Thu Mar 20, 2008 1:35 am

DDS wrote:Pedi, I see you have Mitsubishi Lancer, Evo, if I'm not mistaken. I have Mitsubishi Lancer too, but not Evo.

This is not my car, it is brenzbmr@sb...

I am a BMW guy (even though I am doing my install in a Volvo---"

brenzbmr@sb · Post by **brenzbmr@sb** » Thu Mar 20, 2008 11:57 am

Pedi wrote:
DDS wrote:Pedi, I see you have Mitsubishi Lancer, Evo, if I'm not mistaken. I have Mitsubishi Lancer too, but not Evo.
This is not my car, it is brenzbmr@sb...

I am a BMW guy (even though I am doing my install in a Volvo---"

yeah im a BMW guy and im doing it in a lexus.......go figure.

brenzbmr@sb · Post by **brenzbmr@sb** » Thu Mar 20, 2008 11:59 am

Pedi wrote:
brenzbmr@sb wrote: actually those are all rev b boards. late model b boards came with the
newer front end.
What? Seriously?

- Just another thing I did not know...

But normally the C-boards have the new end.. right?

yes i believe all the c boards have the newer front

i have one rev b that has the newer front end
and the one in the picture i sent in years back for noise issues
roland at pg ask me if i would be interested in upgrading the front
(good price too) and so i did.

Post by **Bfowler** » Thu Mar 20, 2008 12:02 pm

brenzbmr@sb wrote:
Pedi wrote:
DDS wrote:Pedi, I see you have Mitsubishi Lancer, Evo, if I'm not mistaken. I have Mitsubishi Lancer too, but not Evo.
This is not my car, it is brenzbmr@sb...

I am a BMW guy (even though I am doing my install in a Volvo---"

yeah im a BMW guy and im doing it in a lexus.......go figure.

I'm ashamed of both of you!

Post by **mhyde71** » Thu Mar 20, 2008 12:08 pm

DDS wrote:
mhyde71 wrote:However/But, i didnt see that on ampguts like DDS pointed out in his inquiry. I may not be looking right, and I worked a double today on the road looking through a windshied all day...
definately Neat though!
Look for the pics of MS-2125. Most pics (inside view) shows symmetric layout of cables inside the amp. But the last pic (side view, terminal panel) shows L&R inputs and outputs placed close together.

I still think, that the last pic on amp guts (terminal panel) is a 2125 and not a 2125ta.. maybe I'm wrong.. but looks like it anyways. And that's whay the difference in "Layout"... or maybe I'm just not getting it. dunno .. i kinda of moved on though but would like to have an understanding of what the difference is if it is not a 2125 (orig).