so im looking at all these amp guts...

[bubbagumper6 5,000+ posts]

If you really want to learn, there's more than a few pages over on http://bcae1.com/ that will help you.

 

[BnGRacing 10+ year member]

whats wrong with things made in the USA?

Do you know the difference between Made in USA and Assembled in the USA?

Here's an example;

An exercise treadmill is assembled in the U.S. The assembly represents significant work and constitutes a "substantial transformation" (a term used by the U.S. Customs Service). All of the treadmill’s major parts, including the motor, frame, and electronic display, are imported. A few of its incidental parts, such as the handle bar covers, the plastic on/off power key, and the treadmill mat, are manufactured in the U.S. Together, these parts account for approximately three percent of the total cost of all the parts. Because the value of the U.S.-made parts is negligible compared to the value of all the parts, a claim on the treadmill that it is "Made in USA of U.S. and Imported Parts" is deceptive. A claim like "Made in U.S. from Imported Parts" or "Assembled in U.S.A." would not be deceptive.

From here

So while all the parts are put together in the US, the board and 'sink can be made in China (or wherever). That's kind of deceptive if you ask me...

 

[optimusprime 10+ year member]

eh i often assume that most things are made in other places and assembled in the USA.

 

[hispls 5,000+ posts]

The weak point in that amp is pretty much the same as any amp; the fets & toroid.
The parts that determine how low of an impedance you can run at are the output transistors. From the looks of things, and without knowing the make/model of the fets, I'd say that's a high voltage amp. You have 4, probably bipolar, transistors per channel and a somewhat weak power supply for high current use. If it was a high current (low impedance) capable amp, you'd normally see more output transistors and the power supply toroid would be grounded directly to the mosfets. ******* up that much current through the traces on a board is what sent a lot of the old Soundstream amps to the dumpster.

I wouldn't trust anyone to upgrade that amp. If they say they can, they're lying. It's just not beefy enough. Older amps tend to have been WAYYY overbuilt and their power supplies had no problem with upgrades. You'd have to swap out all the switching devices for something that is made for high current useage and you'd have to modify the power supply so that the board doesn't melt. Basically, you'd be paying more in mods than the amp is worth while being left with an inferior product.

That's not a bad looking amp. It isn't a power house, but it probably sounds OK. I'd leave it alone.

Actually the power supply and output devices are pretty overbuilt for what it is... 75X2 @ 4 ohm (not intended for low impedence). These sound amazing actually and are rock solid. This line of amps got really great reviews and for good reason, they were really really nice.

http://www.zedaudiocorp.com/pdfs/ZedManual-2005.pdf

To answer OP, you can't just swap components and make an amp stable down to lower impedence. That part is decided in the design stages and it's not just a matter of throwing different parts in the same circuit.

 

[akheathen Premium Member]

lol, it's kinda hard to just look at some guts and really say what makes it up. first thing, is you have to know what is what..... all those things clamped to the heatsink are transistors, and most of the time, a pair, or more(larger amps) of diodes, but i have also seen them mounted right to the board..... ok, here is a quick rundown- the ampo starts with the power supply. you will see these transistors, or "fets" as most you will ever see are mosfet. they can pretty much be identified by them being connected basically direct to the 12v inputs, usually right to ground. in this section, they switch the power(controlled by that cluster of smaller components nearby on the board, and sometimes their own little board, or "card" you will see them in mostly the smaller to-220 case, and can usually handle a typical 100-150, and even sometimes as high as 175watts as rule of thumb (this is not really set, just quick, and the newer, generally carry more load) sometimes you will see them in a larger to-227 case, which is typically doubble power handling, though you probably will only see it on old stuff, so i would place them in the 150-250 range(again, just quick glance rule of thumb) now, they alternate the 12v through the transformer "torroid" (round thing with wires wrapped around it) now, this, is more looking at the physical size. take for instance, the usamps old school ones barely had any wire on them, but still ran more current than some of the new balls of wire. there, it will hit the diodes, which could be little black cylinders with a silver end, or the to-220/227 cases. there, it is back to dc power. again, there is control circuits similar to the power supply circuit. and, you will see the output section of transistors. again, same thing applies as the power supply fets. difference being, is that the power handling is generally half what the power supply fets run. now, this, again, the newer, generally the more power each transistor can handle, and new designs are moving more to fets, verry similar to power supply fets, and the power jumps exponentially. for instance, i just repaired a soundstream rub1.1600d.... well, @1600watts, it only housed 8 outputs, but pretty much does rated..... the outputs are easily identified by the large resistors going to each one(either little roundish things with colors, or bigger white ceramic boxes.) i generally like to look at the ratio. 2 outputs per power supply fet is usually a good sign, and i count 1to-227 as 2 to-220's.... now, all of this, is just skimming the guts for about 2-3 seconds, and there is a tonne more things you need to know or look at/look-up/test to actually know, or get in a good ball-park. as to the regaurds of modifying an amp for lower impeedance, well, the outputs can only handle soo much current, and so much wattage. i have not done, or had the mod done, nor really have interest in it, but here is how i see it- ideally, if it is 4ohms, then you stand a chance there is some current to be squeezed, however, the wattage is probably already no more than you really want, probably a tad under stable limits. so, as long as the control circuits can accept it, and all the other variables, then the rail voltage will need to be dropped by re-wrapping the torroid or other power supply reconfiguring, and some other stability changes, including cooling, because lower voltage, higher current is usually higher heat, and likely less efficiency. if you want lower impeedance, use a more high current oriented amp. as for "made in usa, or assembled in usa, well, it's still usa that is building it, and i want my components to come from a place that can build it better, which is not america. i don't buy american fets, american caps, and don't plan on it for a while, but a good 'ole american heat sink, board, fateners, wire, quality control, etc.... well, that is a nice combination.... oh, and that treadmill would probably be built with american steel and rubber.... have you ever seen what it would cost to ship? not quite cost effective, atr least not if i was building one..... but, hell yah, i would buy the controller form asia, and motor from somewhere like mexico, or possibly even look for something us, or wherever.... besides, the us sticker gives any product a +1 in my book

 

[Parker G 10+ year member]

I know sound digital had a thread somewhere that had the parts labeled and what not so users knew what parts did what.