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Old 19th February 2004, 08:00 AM   #1
michael is offline michael  Australia
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Default Typical newbie question

I hope this is not too annoying as im sure you get these darn questions all the time.
I really dont know the difference between solid state, chip amps, and pass labs amps. I am looking into the cost to upgrade my setup by adding power amps, i have a NAD 5.1 receiver and it has preouts. It is rated at 50w with all channels driven and has 90w dynamic power.
SO for a decent up grade i spose if be looking at around 100w per channel for power amps.
I know this is a bit vauge but i dont know diddily about diy-amps.
If i need to go post in a different section let me know. Im just after a price of what it would cost me to build power amps for my setup, first 2 channel for my music then 5 for HT. Please help me out, even just some direction is helpful, links etc.
Thanks
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Old 19th February 2004, 10:47 AM   #2
Morse is offline Morse  United States
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Default Long, boring reply.......

Hi Michael;

>>>...I really dont know the difference between solid state, chip amps, and pass labs amps...<<<

That part's easy; in the context of this forum, "chip amps" are amplifiers in which the entire amplification circuit uses an IC chip. "Solid state" in this context refers to those amps that use discrete solid state components (i.e. separate transistors, rather than chips that are packages containing a number of prewired transistors), and "Pass Labs" refers to discrete designs by Nelson Pass.

>>>...I am looking into the cost to upgrade my setup by adding power amps, i have a NAD 5.1 receiver and it has preouts. It is rated at 50w with all channels driven and has 90w dynamic power.
SO for a decent up grade i spose if be looking at around 100w per channel for power amps...<<<

Nothing wrong with upgrading to separates. However, I do question the idea that "more power" = "upgrade". The best DIY system I've yet built went in the other direction - to a little over 4 watts - yet has more ability to convey emotion and delicacy to music than earlier (and later) systems (though to be fair, that one cost nearly $1000USD to build and these days I'm trying to match it's performance for lower cost). It uses valves rather than solid state, but the principle holds that more is not NECESSARILY better. Are you sure you need more power for your speakers? What kind of speakers do you have? What kind of music do you enjoy? What sorts of volume do you listen at?

>>>...Im just after a price of what it would cost me to build power amps for my setup, first 2 channel for my music then 5 for HT. Please help me out, even just some direction is helpful, links etc...<<<

That one's a real hornet's nest. The cost of a decent sounding budget chip amp can be as little as $50 for both channels using cheapie components and giving about 16wrms to 18wrms. However, for 100wrms you're going to either a. bridge something like a pair of LM3886's for each channel, b. use some chips I'm not familiar with or c. go to discrete solid state. If you were to want a high powered valve amp, I'd say that you could get away with something like a push-pull 6550, to the tune of maybe 50 wrms per channel (valve amps tend to sound "louder" watt per watt than solid state designs due to their clipping characteristics - when I first went back to valves, my 40 wpc EL34 amp was easily able to keep up with a 75wpc solid state Yamaha, for example). Cost there will be pretty high - figure around $500USD in parts alone, plus the cost of a matched quartet of 6550's and some small signal valves (maybe $120+ for new production valves per set, and you'll want spares).

AND, a high powered valve amp is not for beginners. Better to try a low watts SET valve amp or better yet, a chipamp (easier and FAR SAFER for a beginner!). High powered discrete semiconductor amps are not a particularly good starter project either, IMHO. The easiest starter project would be something like a Chu Moy chipamp to power your headphones. Go to headwize.com and check their library of DIY projects for details of that one - figure you can build one for under $40, total. Next up in cost and ease of construction would be something using an LM1875 - be sure to use shielded cable for both the inputs and outputs, and do some reading of the archives here for information on layouts. You could go with a PCB or P2P ("dead bug") wiring for something like that. If you're willing to go to around 50-55wrms, look into the LM3875.

In general, the biggest cost in any solid state amp (including chipamps) is going to be the power supply transformer. Figure that for each channel at 100WRMS that you are going to need a minimum of 100VA (and many people will go far higher on general principles!) transformer. Take a look at Parts Express' list of Avel Lindberg torroidal trafos for reference and bear in mind that you're going to need to get over 100VA per channel (so if you double up channels you could get by with a 250VA model). The chips themselves can actually be pretty cheap. LM1875's (good to about 20wrms each) can be had for around $2.5USD, and LM3875's (good to about 56wrms each) are between $5USD and $6USD. Capacitors for the Power Supply (PS) are another cost. In general GainClone guys generally like to keep those small (for solid state; valve amp guys like me use much less capacitance but we also use inductors in our PS filters and those are $$$), but they can be pricey even so, if you insist on the likes of Black Gate (think $$$ when you read the words "Black Gate"). Panasonic caps are good, as are Nichicons, so you don't have to break the bank here. Then there's the heat sink. Particularly for a higher powered amp you're going to need a big one for cool operation. And if you're dreaming of class A operation in a discrete solid state amp, you're going to need an enormous heat sink for 100wrms per channel - class A amps are the least efficient type though they have some theoretical advantages over class B and hybrid class AB types.

Assuming I've not put you to sleep with all this (God knows I could use a bit - it's another evening of insomnia over here! ), I'd suggest that you do a bit of reading and get it clear in your head what you want to accomplish. There's nothing wrong with wanting more power - if your speakers need it. If you're using higher efficiency types (my current 'best' DIY speakers knock out 96dB SPL on a single watt, so it's not like I often use more than 1 watt, period), then wattage alone is a bit of a waste. If you're after "higher quality" watts (i.e. midrange "to die for", etc.) that's another matter entirely.

All this is just a collection of my own opinions. Others may differ, natuerlich.

Good luck on finding and building a DIY amp that will do just what you want and all the best!
Morse
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