M vs MS

Post by **Bfowler** » Tue Aug 21, 2007 12:21 pm

1moreamp wrote: If you arrange enough output devices on any amp it will do what the concept does, Play into speaker wire loads

umm....can you say that again but dumber. that was wasted on me

Post by **stipud** » Tue Aug 21, 2007 12:28 pm

Bfowler wrote:umm....can you say that again but dumber. that was wasted on me

Basically low impedance is like a fat chick. You have 5 chicken wings (transistors) to feed a fat chick, and she will still be hungry. If you have 30 chicken wings, she will be well fed, despite that the chicken wings are operating at the same rail voltage.

Except speaker wire loads are like bulemic crack sluts. You can feed them endless quantities of chicken wings and they just barf it all out. They are always hungry.

Post by **Bfowler** » Tue Aug 21, 2007 12:37 pm

ah-ha!

1moreamp · Post by **1moreamp** » Tue Aug 21, 2007 1:16 pm

yeah what he said

Post by **smgreen20** » Tue Aug 21, 2007 5:23 pm

I never tire of the way things get explaned. LOL

That is the only bummer though, you'd have to use to many speakers to drop it down that low and in the end that's about 1-2 watts per.

fordtough1 · Post by **fordtough1** » Tue Aug 21, 2007 8:17 pm

Yeah, I never understood the point of having them stable at that load. I mean where is the real world application for that?

It is a cool spec though.

ezamps · Post by **ezamps** » Wed Aug 22, 2007 12:54 pm

1moreamp wrote: Your amp you got from me has a switch inside I added < its not stock for that amp> it lets you run your amp in MPS mode or MS mode . I told you your amp was different from everybody else's out there, remember ???

You're not the only one to do this.

Anyway, do you have any idea where I can nab the replacement gold screws for the M100? I LOST MINE!

Aaron

1moreamp · Post by **1moreamp** » Wed Aug 22, 2007 2:28 pm

ezamps wrote:
1moreamp wrote: Your amp you got from me has a switch inside I added < its not stock for that amp> it lets you run your amp in MPS mode or MS mode . I told you your amp was different from everybody else's out there, remember ???
You're not the only one to do this.

Anyway, do you have any idea where I can nab the replacement gold screws for the M100? I LOST MINE!

Aaron

Call PG on the 800 number and ask for Phil Koehn if he has them you can buy them I heard

ezamps · Post by **ezamps** » Wed Aug 22, 2007 3:55 pm

[/quote]Call PG on the 800 number and ask for Phil Koehn if he has them you can buy them I heard

[/quote]

Tanks! I never thought about using acrylic as the top lid. My lid is beyond repair - very badly damaged and scratched. I'm sure you wouldn't mind if I copied your idea, would ya?

Actually, I don't even need the amp if someone wants to make me an offer with the crappy lid. I have replaced the SMPS controller IC and the FETs at some time in the past. I have also replaced the primary-side filter caps. It works fine, but it's been in pieces for years. I lost the screws some time ago...

Anyone? Bueller?

marko · Post by **marko** » Wed Aug 22, 2007 10:02 pm

i'm interested in the beat up m100 if your willing to ship to the uk, i have plenty of referances, pm me an offer

mark.

dgoodhue · Post by **dgoodhue** » Thu Aug 23, 2007 3:28 pm

1moreamp wrote:It would explain why Vin's last M-100 had 5 times as much bias on one channel causing it to overheat by the way, then its partner right beside it that was running cool but not to distortion spec either.

I see bad bias all the time right out of the box new, and you are correct about it being some ill trained persons fault.

One of my M25 runs noticably hotter than other. DO you think this could the difference? Could I adjust the bias with an oscillloscope (and sin wave input)?

1moreamp · Post by **1moreamp** » Thu Aug 23, 2007 4:36 pm

dgoodhue wrote:
1moreamp wrote:It would explain why Vin's last M-100 had 5 times as much bias on one channel causing it to overheat by the way, then its partner right beside it that was running cool but not to distortion spec either.

I see bad bias all the time right out of the box new, and you are correct about it being some ill trained persons fault.
One of my M25 runs noticably hotter than other. DO you think this could the difference? Could I adjust the bias with an oscillloscope (and sin wave input)?

To validate your temp issue I would bench both amps and test them (but thats me). try swapping them around and see what happen temp wise.

Now if the problem stays with the amp Your Bias voltage could be set too high. This causes the output stage to idle at higher current draw sometimes and this can add to heat saturation of the sink. Or it could a whole different combination of things causing the issue.

Try swapping the amp signals and then loads, one at a time as a finger to point at what might be doing this outside the amp first.

There is a voltage measurement method inside the amp, but I am trying to keep you where its safe. One slip of the probe and "Snap' its shop time.

C

dgoodhue · Post by **dgoodhue** » Sat Aug 25, 2007 3:37 am

1moreamp wrote:Now if the problem stays with the amp Your Bias voltage could be set too high. This causes the output stage to idle at higher current draw sometimes and this can add to heat saturation of the sink. Or it could a whole different combination of things causing the issue.

Try swapping the amp signals and then loads, one at a time as a finger to point at what might be doing this outside the amp first.

There is a voltage measurement method inside the amp, but I am trying to keep you where its safe. One slip of the probe and "Snap' its shop time.

I haven't switch amps yet, but its not so easy. My amps are mounted under my front seats, plus I can't physically change them since one of my M25's is series I with a power cable and the other Series II. The ground for both amps is the same and I daisy chain the power in (Power comes into the Series II and I have the power wire of the series one connected to that.) The signal for both is coming from a PG crossover. If I switch signals I have to do some type of hacky speaker.

On a long trip, the Sub M25 (series II) with the volume 3/4-7/8 of the way up will get so hot you are on verge of burning your finger. The other one will be warm to the touch. I do have the gains higher on the sub amp than the front components. One thing that did alarm me is my sub M25 ran hot even with out a load. Not as hot as with a load, but probably twice as warm as the other M25. I have upgraded the input capacitors

I am not worried about measuring a signal on the M25. I am a Manufacturing Test Engineer for telecommunications test equipment company (IPTV). I basically debug the harder problems the tech's can't figure out and track the problems/solutions to improve the manufacturing process. The parts I have to solder to make board repairs are far smaller than anything on a M25. if its in a tight area, I could just tack a wire lead on the part.

1moreamp · Post by **1moreamp** » Sat Aug 25, 2007 9:16 am

OK let me put your mind to rest about the heat related issue. Its bass power causing your amp to heat up, Its not misaligned IMO.

Any class AB amp used for bass line will run hotter than a same equal amp running mids and tweets. there are several reasons, but the most prevalent is the fact that bass is low frequency information and therefore causes longer storage effects in the transistors. The other reason is most folks run bass amps a lot harder than their mids and tweets amps.

Bass requires more power, sometimes by as much as a factor of ten. So having a bass amp run hotter then the same mids and tweets amps is pretty common place and not a sign of mis-alignment IMO.

The rest of this is at your own risk. You asked for information, I gave it. How you use it and the net results are YOUR responsibility.

The required measurements are located inside on the output transistors. There are a set of resistors that couple the outputs to the speaker terminal. Attaching a probe to the + speaker terminal, and then the other probe to the other side of either of these resistors will give you the exact amount of turn on for each transistors.
It should be equal for either resistor, and you measure directly across both of these these two together to get a total on idle voltage drop across these resistors. The reading will be in DC Milli-Volts range<0.001 = 1 miili-volt DC.> And possibly as low as to be in the Tenths of Milli-volts DC.

If your bias is too low, there will be zero reading. This is a sign of no or too little turn on to the output stage. The correct amount will give you the rated distortion spec for the amp, and should be measurable with a voltmeter across the resistors.
The exact reference spec from PG is not known in most cases, so a distortion meter, a very pure signal source, and a scope are needed to set this properly.

Hence my trepidation about even mentioning anything about doing this to even a advanced person like you. It requires thousands of dollars worth of alignment tools to do this correctly.
Now this does not mean that you can't call PG and beg them to release a ballpark figure for you to align your amp to. On a good day, and the planets aligned with a kind word into the right persons ear at PG you might get a ballpark guesstimate set point that will give you a Feel good feeling about your completed efforts, Maybe.
Oh and remember any set point must be spec'ed a at given ambient temperature. So the set point is only valid if the sink temperature is at the rated temp. And you must verify these distortion measurements across the 20 to 20k bandwidth, not just at 1 kilo-hertz. < no cheating please>

Be fore warned:
Tampering with this set point can destroy your amp. This adjustment will not make your amp more powerful. It will not turn your amp up inside < like I have seen others try, mostly Rockford owners> ALL PG amps have this adjustment. and so does many other old school amps like PPI, ZED/Hifonics, Adcom, and many many others...
It is only there to be adjusted so the amp meets spec for rated distortion, and to align the output turn on voltage so the outputs stage is bias on so the transistors will swing across the zero voltage point without introducing distortion. This distortion occurs when you use the music drive level to switch the outputs on due to insufficient on voltage from the amp as built. This distortion is commonly referred to as "Crossover Notch Distortion"

Too much bias and you will "let the smoke out of your amp".

This adjustment is very fine, and must be done by someone that has done it more than once in his life < I have done thousands >. This adjustment exists by the hands of PG engineering so it was meant to set correctly, and set by the maker PG when it was built.

And for EricD this set point is a 200 ohm pot, I can't really imagine a much finer adjustment pot except maybe a 100 ohm pot.

This set point is temperature sensitive, and must be check across a set of temperatures to ensure its stable, and correct even with heat induced drift . If set too high your amp will go into thermal runaway and self destruct < i.e. Burn UP >

there goes your smoke

Remember those labels " No User Serviceable Parts Inside, Warranty Will Be Void If Seal Is Broken " well this is what they were talking about when they put that label there.

I have given you the info you requested, BUT I have also warned you vigorously about the down side of tampering where angels should fear to tread.
I don't want anybody coming back to me saying I didn't warn you. I did

:!:

This is not for beginners, and not for the unqualified that don't completely understand it from A to Z

nico boom · Post by **nico boom** » Sat Aug 25, 2007 12:37 pm

Quote;,..except for nico who will undoubtedly have the baddest home stereo on the planet...

Thanks TWISTED, for judging my install from the other side of the ocean.
Lucky for me, I don't give such negative critics on other people's way to enjoy their hobby, nor the quality of it, because that's just not my bussiness....

My install, and my ears may not be perfect, but I enjoy my install every day; so who are you, to call it "undoubtedly the baddest home stereo on the planet"?

I hope you have perfect hearing, and a perfect install, and in the future think twice, before judging a system you've never heard.
nico

Post by **smgreen20** » Sat Aug 25, 2007 12:45 pm

Well, I'm not so tempted to mess w/the pods inside of an amp anymore. I've always wondered what they do, just didn't know, and now I do.

Post by **AVICJR** » Sat Aug 25, 2007 12:54 pm

nico boom wrote:Quote;,..except for nico who will undoubtedly have the baddest home stereo on the planet...

Thanks TWISTED, for judging my install from the other side of the ocean.
Lucky for me, I don't give such negative critics on other people's way to enjoy their hobby, nor the quality of it, because that's just not my bussiness....

My install, and my ears may not be perfect, but I enjoy my install every day; so who are you, to call it "undoubtedly the baddest home stereo on the planet"?

I hope you have perfect hearing, and a perfect install, and in the future think twice, before judging a system you've never heard.
nico

Nico-- The term "bad" in the States is slang meaning good or awesome. Twisted was complementing, not criticizing. "Bad Ass"= Really good or kicks ass.

Think of the song by George Thorouhgood "Bad to the Bone".

Scroll down to the word "bad".
http://onlineslangdictionary.com/browse/b

brenzbmr@sb · Post by **brenzbmr@sb** » Sat Aug 25, 2007 1:42 pm

i think we need to make a sticky for our international members on our
slang so they understand that we are not putting them down...
and visa versa, i think knowing some british slang is cool too.

nico he was simply complimenting you on your set up...

aloha

fordtough1 · Post by **fordtough1** » Sat Aug 25, 2007 1:43 pm

Yeah, by baddest I know he meant nicest, coolest, awesomest, (insert your own adjective here).

He meant no disrespect.

1moreamp · Post by **1moreamp** » Sat Aug 25, 2007 1:52 pm

nico boom wrote:Quote;,..except for nico who will undoubtedly have the baddest home stereo on the planet...

Thanks TWISTED, for judging my install from the other side of the ocean.
Lucky for me, I don't give such negative critics on other people's way to enjoy their hobby, nor the quality of it, because that's just not my bussiness....

My install, and my ears may not be perfect, but I enjoy my install every day; so who are you, to call it "undoubtedly the baddest home stereo on the planet"?

I hope you have perfect hearing, and a perfect install, and in the future think twice, before judging a system you've never heard.
nico

He meant good in a american way Nico

Twisted is good people to, just like you my friend.

"Baddest "means, great to the point of stupendous, or just plain Best, here in the States.
It would be like me saying I have the baddest transistors, what it really means is the "best".
American street slang is confusing, especially when it gets played by the Queens English which is what you folks here the most in Europe.
We butcher the language really well over here. I hope this helps you to understand my friend C

twisted · Post by **twisted** » Sat Aug 25, 2007 1:57 pm

nico boom wrote:Quote;,..except for nico who will undoubtedly have the baddest home stereo on the planet...

Thanks TWISTED, for judging my install from the other side of the ocean.
Lucky for me, I don't give such negative critics on other people's way to enjoy their hobby, nor the quality of it, because that's just not my bussiness....

My install, and my ears may not be perfect, but I enjoy my install every day; so who are you, to call it "undoubtedly the baddest home stereo on the planet"?

I hope you have perfect hearing, and a perfect install, and in the future think twice, before judging a system you've never heard.
nico

nico,
i meant no disrespect to you or your home stereo!!!!! i infact was complimenting it! baddest as in bad ass sir

i think the ms amps will rock in your house.
im SORRY if i offended you but that WAS NOT my intention. i was complimenting only.