Input voltage MS-Series Amps

Post by **joerg** » Sun Apr 05, 2009 1:46 pm

Matt and i had a discussion about the input voltage for the MS series Amps yesterday. He mentioned that a member in here told him to get rid of his linedriver amplifier because the MS series amps do not take input voltage above of 2.2volts.

So here is the clue! At my first install i used to run my Sofas with a headunit fom rockford fosgate! It was i RFX-8140 This unit has an preamp output voltage of 8.5 volts!!! And it did not harm my first SOFAS at any time! So what´s the point of keeping the input voltage below 2.2 Volts???

Thunderdome · Post by **Thunderdome** » Sun Apr 05, 2009 1:53 pm

this is true I always ran mine at 4 volts for years and no problems either and sure boosted the output

anyone know the deal

dBincognito · Post by **dBincognito** » Sun Apr 05, 2009 2:13 pm

joerg wrote:Matt and i had a discussion about the input voltage for the MS series Amps yesterday. He mentioned that a member in here told him to get rid of his linedriver amplifier because the MS series amps do not take input voltage above of 2.2volts.

So here is the clue! At my first install i used to run my Sofas with a headunit fom rockford fosgate! It was i RFX-8140 This unit has an preamp output voltage of 8.5 volts!!! And it did not harm my first SOFAS at any time! So what´s the point of keeping the input voltage below 2.2 Volts???

MS2250's are rated up to 5 volts

As far as I know.....you could be taking a chance at frying the circuits......as they are rated to accept a maximum voltage, just like the input voltage for the B+ can only go so high.....and then the amp will fry

These ratings could be under-rated and that may be why you are able to run a higher voltage without a problem. But it can cause problems taking the input voltage too high on the RCA's

dBincognito · Post by **dBincognito** » Sun Apr 05, 2009 2:18 pm

All of the TA's accept 5 volt input

STROKD · Post by **STROKD** » Sun Apr 05, 2009 2:28 pm

The older MS amps go to 2 volts on the gain and the newer ones and TAs are all 5 volts. I ran a 4 volt alpine to my FAS for years, but when I added my EQ230, and if you turn the gains up just too much on the input gain, they over saturate the gain going to the amp and it sounds REALLY distorted... I think I have it set around 5-6 volts max, and it sounded killer... just be careful not to over drive the input stage, if it sounds distorted IT IS!

phonixx · Post by **phonixx** » Sun Apr 05, 2009 8:48 pm

I think some of the headunits we are using is not really giving the output it should,maybe its max values but not Rms. I also have a 4V Alpine deck but its not giving out more then approx 2.2VRms so i use a SLD44 to get 8V for my RSD amps. I take out approx 1.5V from the deck and leave the rest to the SLD44, then i think i avoid any distorted signal to the amps.

Bjornar

dBincognito · Post by **dBincognito** » Sun Apr 05, 2009 8:50 pm

phonixx wrote:I think some of the headunits we are using is not really giving the output it should,maybe its max values but not Rms. I also have a 4V Alpine deck but its not giving out more then approx 2.2VRms so i use a SLD44 to get 8V for my RSD amps.

Bjornar

Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate

Post by **joerg** » Sun Apr 05, 2009 9:04 pm

dBincognito wrote:Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate

My RFX8140 has 8,5 Volts for sure! Tested it with some pink noise and a meter!!!

dBincognito · Post by **dBincognito** » Sun Apr 05, 2009 9:07 pm

joerg wrote:[quote="dBincognito]Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate

My RFX8140 has 8,5 Volts for sure! Tested it with some pink noise and a meter!!!

[/quote][/quote]

Maybe they lied about the input voltage

Post by **ttocs** » Sun Apr 05, 2009 9:50 pm

phonixx wrote:I think some of the headunits we are using is not really giving the output it should,maybe its max values but not Rms. I also have a 4V Alpine deck but its not giving out more then approx 2.2VRms so i use a SLD44 to get 8V for my RSD amps. I take out approx 1.5V from the deck and leave the rest to the SLD44, then i think i avoid any distorted signal to the amps.

Bjornar

actually the problem is with the meter. Digital Meters are made to read rms voltages when reading AC voltage and remember we are wanting peak readings. The rms readings are .707 times the peak power so your 4 v max output will show up as a max reading of 2.82v if everything is perfect.

The other problem with reading rms values on a digital meter is that once it reaches clipping the rms value will not change much since it is still showing .707 times the peak power but remember that when it reaches its peak it will clip the signal so your meter will still show the same reading.

When tuning a system the ONLY tool that will show what you are actually hearing is a an O-scope. Tuning a system with a multimeter is like using a flat head screw driver as a chizel. It CAN work if you have to but should really be avoided.

Post by **joerg** » Mon Apr 06, 2009 3:07 am

ttocs wrote:
phonixx wrote:I think some of the headunits we are using is not really giving the output it should,maybe its max values but not Rms. I also have a 4V Alpine deck but its not giving out more then approx 2.2VRms so i use a SLD44 to get 8V for my RSD amps. I take out approx 1.5V from the deck and leave the rest to the SLD44, then i think i avoid any distorted signal to the amps.

Bjornar
actually the problem is with the meter. Digital Meters are made to read rms voltages when reading AC voltage and remember we are wanting peak readings. The rms readings are .707 times the peak power so your 4 v max output will show up as a max reading of 2.82v if everything is perfect.

The other problem with reading rms values on a digital meter is that once it reaches clipping the rms value will not change much since it is still showing .707 times the peak power but remember that when it reaches its peak it will clip the signal so your meter will still show the same reading.

When tuning a system the ONLY tool that will show what you are actually hearing is a an O-scope. Tuning a system with a multimeter is like using a flat head screw driver as a chizel. It CAN work if you have to but should really be avoided.

Because we knew about the factor .707 from the digital meters we used a analog one when we measured the voltage on my RFX8140--

Post by **ttocs** » Mon Apr 06, 2009 6:38 am

Post by **stipud** » Mon Apr 06, 2009 7:05 am

joerg wrote:
dBincognito wrote:Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate
My RFX8140 has 8,5 Volts for sure! Tested it with some pink noise and a meter!!!

That's not how you test it... you have to use a 60Hz test tone (with a US multimeter), or a 50Hz test tone (with a european multimeter) set to read A/C volts.

Also, it will only put out 8 volts at maximum volume. Assuming you never go that high, it is probably only at or below 2v most of the time, which is why you haven't fried an amp yet. My recommendation would be to figure out at what point on the volume knob you get 4v out of your multimeter (using the test tone), and avoid going above that level at all costs.

Rest assured you can blow an MS amp with an 8v headunit playing a test tone at full volume. The amp will try to produce way more than it's capable of, clip and fry.

dBincognito · Post by **dBincognito** » Mon Apr 06, 2009 7:09 am

stipud wrote:
joerg wrote:
dBincognito wrote:Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate
My RFX8140 has 8,5 Volts for sure! Tested it with some pink noise and a meter!!!
That's not how you test it... you have to use a 60Hz test tone (with a US multimeter), or a 50Hz test tone (with a european multimeter) set to read A/C volts.

Also, it will only put out 8 volts at maximum volume. Assuming you never go that high, it is probably only at or below 2v most of the time, which is why you haven't fried an amp yet. My recommendation would be to figure out at what point on the volume knob you get 4v out of your multimeter, and avoid going above that level at all costs.

Rest assured you can blow an MS amp with an 8v headunit playing a test tone at full volume. The amp will try to produce way more than it's capable of, clip and fry.

There are amplifiers designed to accept these higher voltages correct ?

Such as old school RF, and Rubicon right ?

Post by **joerg** » Mon Apr 06, 2009 7:09 am

ttocs wrote:lol

I don´t know why are u laughing but i know for sure that a analog meter is much faster than a dmm! And with the benefit of a hold min-max value it is a very good thing to go with! For sure a o-scope would have been better but compared to what we needed it for it wasn´t worth to buy the o-scope!

dwnrodeo · Post by **dwnrodeo** » Mon Apr 06, 2009 7:35 am

stipud wrote:
joerg wrote:
dBincognito wrote:Ding...Ding...Ding....we have a winner.....you should multimeter your RCA's and find out what the "real" voltage is....if you want to be accurate
My RFX8140 has 8,5 Volts for sure! Tested it with some pink noise and a meter!!!
That's not how you test it... you have to use a 60Hz test tone (with a US multimeter), or a 50Hz test tone (with a european multimeter) set to read A/C volts.

Also, it will only put out 8 volts at maximum volume. Assuming you never go that high, it is probably only at or below 2v most of the time, which is why you haven't fried an amp yet. My recommendation would be to figure out at what point on the volume knob you get 4v out of your multimeter (using the test tone), and avoid going above that level at all costs.

Rest assured you can blow an MS amp with an 8v headunit playing a test tone at full volume. The amp will try to produce way more than it's capable of, clip and fry.

http://webfaq.phoenixphorum.com/technical_questions.htm

Near the bottom of the page it says any amp will handle 8v (not a test tone of course).

dBincognito · Post by **dBincognito** » Mon Apr 06, 2009 7:46 am

dwnrodeo wrote:http://webfaq.phoenixphorum.com/technical_questions.htm

Near the bottom of the page it says any amp will handle 8v (not a test tone of course).

Then why are the 2250's and TA's rated higher ?
Why would they print 2 different specifications, if they all handled 8 volts

Post by **stipud** » Mon Apr 06, 2009 7:47 am

dwnrodeo wrote:http://webfaq.phoenixphorum.com/technical_questions.htm

Near the bottom of the page it says any amp will handle 8v (not a test tone of course).

Yes, if you listen to dynamic music. Nowadays people listen to bottom heavy rap or techno which is test tones over music, for all intents and purposes.

I normally advise at most 3dB of extra gain, which is why I told Joerg to find where his volume reaches 4v (which would be 3dB higher than 2v). Running 8v you are trying to use 6dB of additional headroom, which is pushing the limits a bit.

marko · Post by **marko** » Mon Apr 06, 2009 8:20 am

the ax406a has 8v output does it not? then why was it available at the time all pg amps were rated for 2v? because they all took more than 2v! i always ran mine with a lot more with no problems at all.

Post by **fuzzysnuggleduck** » Mon Apr 06, 2009 8:59 am

My M-series amps don't need more than 2V input to get them producing their rated wattage. Of course, I wasn't using a scope, just a 60Hz test tone and a DMM set to A/C voltage. I should really borrow the Fluke TrueRMS meter at work sometime.

vin78 · Post by **vin78** » Mon Apr 06, 2009 9:13 am

IIRC, the MS manual states 4volts input?

Post by **stipud** » Mon Apr 06, 2009 9:21 am

PG says a lot of things. Proofreading on their manuals seems to be nonexistent, so I wouldn't trust it if one thing says 8v is ok, while another says 4v, and another says 2v.

Moral of the story... use your DMM to verify the gains. If you're going to play long tones at 8v into your rare, limited edition 2v MS amps, I guarantee you will break them. PG amps are usually good for 3dB of headroom on dynamic music, but one loud tone played through the system throws that all out of the window.

If your amp makes full power (lets say 500 watts) at 2 volts... it will try to produce 1000 watts at 4 volts, and 2000 watts at 8 volts. It's not hard to see that this will not work for more than a millisecond.

Post by **ttocs** » Mon Apr 06, 2009 2:06 pm

joerg wrote:
ttocs wrote:lol
I don´t know why are u laughing but i know for sure that a analog meter is much faster than a dmm! And with the benefit of a hold min-max value it is a very good thing to go with! For sure a o-scope would have been better but compared to what we needed it for it wasn´t worth to buy the o-scope!

It has been years since I was in school and studied or even had the use of an analog meter but I am fairly sure that on an ac signal that they still read an rms reading. Analogs can be a little more accurate if they are calibrated(rarely done) correctly and if you really take the time to make an accurate reading(counting the lines ect), but I am still almost certain that they do not show the AC peak reading which is what we are after here right?

gentlejax2 · Post by **gentlejax2** » Fri Apr 10, 2009 12:44 pm

woah...glad I saw this...guess I need to pull my line driver out or not use it for my mint MS275 I just got.....

just run it off the 4 volts from the deck...

vin78 · Post by **vin78** » Fri Apr 10, 2009 1:03 pm

gentlejax2 wrote:woah...glad I saw this...guess I need to pull my line driver out or not use it for my mint MS275 I just got.....

just run it off the 4 volts from the deck...

Mint huh? Where did you get that?

Input voltage MS-Series Amps

Input voltage MS-Series Amps

Re: Input voltage MS-Series Amps