LM4702

Joecool85 · February 28, 2006, 08:50:03 PM

Anyone heard of this chip? It seems it puts out 300w!!

Connoisseur of Distortion · March 01, 2006, 02:43:39 AM

http://cache.national.com/ds/LM/LM4702.pdf

looks impressive. 200 volts, though... just imagine the transformer you'd need!

Joecool85 · March 01, 2006, 07:19:32 AM

Yeah, it would be a pretty manly transformer...but hey, for that kind of power, its worth it isn't it?

troubledtom · March 01, 2006, 08:37:20 AM

it's a matter of $$$$$ if the transfomer cost $40 bucks or a $140 bucks , i don't know.
-tom

Sir H C · March 01, 2006, 10:19:46 AM

Such modules have been out for years. Look in a lot of receivers and you see one big module hooked to a heat sink for the power. Remember too that you have to get the heat out of that package so you are going to need quite a good heat sink as it could be handling 100+ watts of waste heat.

RDV · March 01, 2006, 10:29:19 AM

Edit: See my post below.

RDV

phaeton · March 01, 2006, 10:34:35 AM

I dunno... my ears can hurt bad enough from 5W if I'm not careful.

Joecool85 · March 01, 2006, 11:58:10 AM

5w solidstate or in a tube amp?

I can play my 14w amp full tilt without hurting my ears too bad. Although, if I play it through a nice cab its substantially louder and I can't play full tilt without hurting my head.

I'm building a lm3886 amp that will give me 50w and it should be far more than I really need right now. People forget how loud 50w is. My sisters boyfriend has a 250w peavey 2x12 combo and most of the time it never sees 1/4 volume. He has played a few large gigs where he had to have it at 1/2 or so and thats about it. I bet a 50w lm3886 at full volume probably would have been plenty even for that gig. Or if he needed more, a 2x50 would cover it.

RDV · March 01, 2006, 12:48:31 PM

News Flash here(for some of you anyways). I went and did some reading and found that:

This isn't a chipamp, it's a driver for a discrete amp. It's just the front end of a standard power amp. It drives poweramp transistors.

Not a chipamp, doesn't even require a heatsink(at least not a huge one, however the power transistors certainly will).

RDV

phaeton · March 01, 2006, 01:03:07 PM

Quote from: Joecool85 on March 01, 2006, 11:58:10 AM
5w solidstate or in a tube amp?

I can play my 14w amp full tilt without hurting my ears too bad. Although, if I play it through a nice cab its substantially louder and I can't play full tilt without hurting my head.

I'm building a lm3886 amp that will give me 50w and it should be far more than I really need right now. People forget how loud 50w is. My sisters boyfriend has a 250w peavey 2x12 combo and most of the time it never sees 1/4 volume. He has played a few large gigs where he had to have it at 1/2 or so and thats about it. I bet a 50w lm3886 at full volume probably would have been plenty even for that gig. Or if he needed more, a 2x50 would cover it.

5W tube amp in my case. However, my 45W SS Peavey can get insanely loud too, it's just not something you want to listen to at that volume

We all know that "wattage" and "decibels" are exponential, not incremental, right? Also, it all boils down to pushing air, so the more collective speaker area you have, the more effective your 'watts' are. 50W into a 4" driver is nothing on 5W into a 4x12 cab. (oar something like that)

That said, stuff like 100W Fender Twins are *UNGODLY* loud. Even in stage volume situations.

Sir H C · March 01, 2006, 01:32:06 PM

Quote from: RDV on March 01, 2006, 12:48:31 PM
News Flash here(for some of you anyways). I went and did some reading and found that:

This isn't a chipamp, it's a driver for a discrete amp. It's just the front end of a standard power amp. It drives poweramp transistors.

Not a chipamp, doesn't even require a heatsink(however the power transistors certainly will).

RDV

Think this will need a heatsink. Uses 25mA with a 170 volt rail that is several watts of power. Remember, the ground plane of a PCB is often used as a heatsink in modern designs.

RDV · March 01, 2006, 01:51:57 PM

Quote from: Sir H C on March 01, 2006, 01:32:06 PM
Quote from: RDV on March 01, 2006, 12:48:31 PM
News Flash here(for some of you anyways). I went and did some reading and found that:

This isn't a chipamp, it's a driver for a discrete amp. It's just the front end of a standard power amp. It drives poweramp transistors.

Not a chipamp, doesn't even require a heatsink(however the power transistors certainly will).

RDV

Think this will need a heatsink. Uses 25mA with a 170 volt rail that is several watts of power. Remember, the ground plane of a PCB is often used as a heatsink in modern designs.

I guess what I meant was it won't need a 10 lb. one like I thought it would need when I thought it was a chipamp. I almost added that to my edit. The guys at DIYaudio said it would have to dissipate about 4 watts. I don't think I'm interested in this really anyways. I built some amps cause I needed them. I really don't have the fever. A smallish tube amp may be the next thing I try, like maybe a Fender Deluxe size.

RDV

Joecool85 · March 01, 2006, 02:23:47 PM

Same thing here. I just wanted to let you guys know about this. It seems that even though its not a chipamp, it is relatively easy to build and get tons of power out of. 300w is no laughing matter, thats alot of volume.

Connoisseur of Distortion · March 02, 2006, 12:17:48 AM

i dunno... 300W sounds very useful... But then, i am constantly in competition with a drummer, guitarist, vocalist through 350W system, and bassist. Probably about half volume would cover it in most cases.

Joecool85 · March 02, 2006, 07:47:33 AM

What do you use right now?

News:

LM4702