car amp repair man.....

[Spooney 10+ year member]

guess again

Not zed but it is a ppi if it makes you feel any better

 

[amartin_72]

I have an audiopipe gm-1700 600 rms 2 channel for 15 shipped. A jbl gto 1201.1 for 50 shipped - both in protect.

 

[corrie32 10+ year member]

if u say so

 

[77oldsMAbrotha 10+ year member]

you have a PrivateMessage

 

[Spooney 10+ year member]

if u say so

Sounds like you dont believe me. Its cool its a good amp either way but it is a ppi built amp. The bottom plate holds the transistors down to the heatsink does it not? They did this on many oldschool ppi

 

[amprepairman 10+ year member]

I have gotten many many questions about upgrading amps...

Lets talk a little about theory and practical electronics...

There are two kinds of electronics...theory and practical...Theory is what should be happening based on the drawings of some poor guy whos been pulling his hair out hammering away on a calculator that has the numbers and symbols worn off the buttons. Practical is whats actually happening once you put it together and you test it....The difference between the two is sometimes great and sometimes very small and much of it has to do with the parts selected to get the job done.(board layout can play a role in performance and noise as well and you just have to hope that whoever laid out the board knew what they were doing.) ((As a side note...most boards now days are laid out by computers that are capable of making more mistakes in .25 of a second then we could possibly make in five life times)) All parts have cetain tolerance ratings...and the tolerance rating is a factor in the cost of the part, when we consider a passive part such as a resistor tolerance is measured as a % rating..10% tolerance parts are cheaper than5% tolerance parts and so on.... Voltage and current rating are factors in fet selection....there are also other things to consider when selecting a fet for a application but the cost issue usually revolves around current and voltage handling.....some fets and transistors just have better sound quality than others in a audio application and some are designed for just audio applications...And of course capacitors...Virtually all audiophiles have a preference for a capacitor thats going to be installed in the audio stream of their amp...

I have my preferences too.I like to use certain parts based on reliability...sound quality...possible gains in power output..and in some cases cosmetic appearance improvements as well....

So...possible upgrades can include just about replacing every part in your amp...Alot of it has to do with what your starting out with....

POWER SUPPLIES...If you send me a amp and the power supply is bad..Im gonna do any upgrades to it that I know of right off the bat...I dont want the amp to come back for a power supply failure so I'm gonna be sure its right...I start out with the best FET's available for your application. When I fix a power supply ALL the fets are getting changed if ones bad and Im gonna replace then with the best ones I can put in the amp...I usually upgrade to 1% tolerance flame proof gate resistors.I check all the caps...If I have to replace caps I'll call you and we can talk about possible upgrades or just replacing them with the same type. I typically see bad caps in a power supply about 30% of the time...but for the fets and the resistors and simple stuff like that...I consider that part of a normal repair and I dont charge extra for it...

AMPLIFIER SECTION...In the audio end of a amp its a little different..Its not a good idea to upgrade a channel just because it blew up...your channels wont match anymore..so upgrades for audio cost more..in effect its like fixing both channels.or all 4 in multi channel amps..every change you make to a audio section effects sound quality...so if you change one channel...you gotta change them all...When I repair a output channel I concentrate more on getting the bad channel to match back up with the other channel(s) in the amp. If your interested in making changes we can talk about that up front before I start working on it.After I get to look at it and see what is in the amp as it is.

So if I have your amp on the bench and its got a bad power supply I'm gonna comepletely go through it and Im replacing every part thats not perfect and Im gonna use the best parts available to do it..and it has no effect on the total price of the repair.Its the way I've been doing it for years and I wouldnt know how to do it any other way.

If you have a bad channel Im gonna fix it and get it back to spec with the other channels unless your interested in making changes to it..then once I have the amp and see where Im at to start out I'll call and we can talk about the options

 

[MakeshiftAudio 10+ year member]

Oh boy...

I'll be on the standby waiting for shoot through failure. *Sigh.*

 

[njaykaplan 10+ year member]

Oh boy...
I'll be on the standby waiting for shoot through failure. *Sigh.*

Why so negative? He sounds like he has a good idea what hes doing, and buying amps on ebay to show his repairs before going crazy on the forum, hes doing great so far for a new guy.

 

[MakeshiftAudio 10+ year member]

Because everyone can pop CM600s into their amplifier.

 

[amprepairman 10+ year member]

If anyone has questions about a cm600 I'll refer them to you..

 

[MakeshiftAudio 10+ year member]

Haha, okay. I'll send A/Bs your way, and you send the Ds my way, kay?

If you ever want to talk, just shoot me a PM.

The CM600 isn't a fet anyways, it's an igbt. I was just saying that only changing the fet does not make it better necessarily. There are many attributes that are considered when choosing a fet for the job. I will not go into detail on this unless you contact me via AIM or PM. It's pretty lengthly.

 

[amprepairman 10+ year member]

Im tired tonight..so I'll have to pass...I am aware of insulated gate bipolar transisters....and thier applications...I was tryin to just let it go...

I started to school on mosfet theory when IR and Rockford first became friends...

Me and a guy named Heimer were the service techs at HI-FI-FO-FUM here is St.Louis and we were the only dealer and warranty center for rockford anywhere around here. I went to work for them I think in 1990. Back then if you didnt sell it..you couldnt get warranty so we had ALOT of work to do as we were I think the only dealer( I think maybe the first dealer too) in town and the owner managed to keep it that way for awhile too...Rockford made very sure we knew what we were doing...

I am also a graduate of Rankin technical school.. its one of the best tech schools in the united states.1989 electronics

I was fixing amps way before then though....

If you look at the post I put up right before you made your comment it says that there are other things to consider when selecting a fet for a application..or something to that effect..I cant see it as I type this...I just didnt feel like getting that technical would help anyone who was reading it...RDS..VBRDSS...ID...specs of a fet that no-one would have cared to hear about...

I'm 42 years old and Ive been working in electronics all my life....daily...

Replacing a cheap korean made KIA series fet as a example with a IR component of greater current value using the same basic on state resistance with similar temp characteristics without doing any other mods to a amplifier power supply will in fact improve the durability of that power supply..and I have 20 years of positive results to back that up.... Ive done test after test with my own amps to prove it.

Ive taken every class I can that revolves around DC to DC switching power supplies and have even went as far as talking to engineers at texas instruments at lengh reguarding the TI 494 and the 594 and whats really possible to do as far as control and limitations of the chip with the obvious requirements and limitations of the components surrounding the chip being considered...And I've played with the siliconix version too....so the soundstream and the older orion guys wont be left out...

I spent 3 days once at a stupid convention and sat in a room the whole time and listened to some guy talk about frickin diodes...

Ive been to schools and taken classes for just about every major manufacturer out there at one point or another...

Ive done my homework and paid my dues...

Im sorry but it just seemed to me that you were indicating that I didnt know what I was talking about....

 

[murilo 10+ year member]

Very nice, old school here.

 

[ngsm13 5,000+ posts]

Apparently you also don't know how to read the rules when you register for this site...

 

nG

 

[corrie32 10+ year member]

who NG?