what is a chip amp?

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Hi,
a chipamp is an integrated circuit solution that produces power into loudspeaker type loads, with very few other components.

The maximum sensible power from an LM3886 (and some other types) is about 60W into EITHER 4ohm or 8ohm. The voltage from the power supply must be scaled to allow the chipamp to meet either duty.

If you want 500W then about 10 chipamps and a lot of resources will need to be thrown at the design project. I reckon it is better just to go discrete.
If you want to exercise your brain then 5*LM3886 in parallel could do about 250W into 2r0 and be safe in the short term (a few tens of milliseconds) into a 1r0 test load.
Bridging these two sets of 5chipamps together would give about 500W into 4r0.
 
Hi,
If you select your speakers with similar sensitivity and impedance then each will require similar power to reach similar maximum SPL.

Choose 94db/W drivers and 50W amps will give 111db/m at any audio frequency.
You don't need a plate amp unless you choose to mix drivers with very different sensitivities or different impedances.

I recently started a thread over in DIYsubwoofers asking for comment that my sub ticks over on about a quarter of the power being delivered to the mains.
 
cadbury8 said:
so i guess where a chip amp would shine would be an active 2 way system when supplemented by a sub with maybe a plate amp for example.

Chip amps (well the lm3875 I can comment on) shine because the very low component count and very short signal path make for very musical and detailed amplifiers. The amplifier is also very linear in its response due to the design of the chip.

They make a lot of sense into two way systems as you suggest because low component count = relatively low cost. I run mine passively biamped, and next plan to go to passive tri amp. The low cost of each amp stage make this very worthwhile. The other advantage is even a diyhifi noob like myself can build one quickly and get amazing results. My current setup out performs a musical fidelity E200

Why do you need 500w? your speakers must be pretty inefficient or your neighbours very forgiving if this is for standard speaker configeration.
 
I dont need 500w of power. I was just curious to what a chip amp was and how much power it was able to deliver. I have never seen anything or heard anything about it before coming to this site. It is quite the curiosity. I read some and did a search on google but was not able to find anything that i understood or could compare to a SS amp.

The first thing i thought of when seeing chip amps was that it was a DIY digital amp.

So with what has been explained i came to an assumption that since the amp isnt very powerful then it would be the best used with an active crossover where you could limit it and make it even more efficient. so if a DIY chip amp sounds very good in a passive design where its doing a full bandwidth then it only makes sense that its sound quality would be exceptional in an active crossover design. And the real beauty of it would be the fact that it could be integrated with the active crossover and perhaps even installed in the speaker. Kind of like a plate amp design. Way cool.

I could see myself implementing something to this effect. Especially if it is cheap to build. Its really just another option.

or even picture this if you will. A line array of 8 tweeters and 8 mids each driver powered by a single chip amp. And all with an active crossover. A single dayton rs125s-8 mid has an RMS of 30/45 watts max so a single 60 watt amp would probably be perfect especially since its only used in freq range of 100 - 120hz to about 2000 to 2500hz. And that would even increase the head room i would think. Maybe im on track with this thought maybe im not. But it would still be very cool either way. :)
 
Hi Cad,
right on.
I have pushed the idea of one amp to one driver for ages and few seem to recognise the advantage.
Avoid 4ohm drivers if you can when using chipamps. They current limit and a low spec version may limit audibly when not driven particulary hard.
 
AndrewT said:
Hi Cad,
right on.
I have pushed the idea of one amp to one driver for ages and few seem to recognise the advantage.
Avoid 4ohm drivers if you can when using chipamps. They current limit and a low spec version may limit audibly when not driven particulary hard.

Ill keep the 4ohm drivers tip in the back of my mind. thanks.

another idea.

Take apart a window shaker and use it to cool the heat sinks as there would be a lot of them. this way your not heating up the room and can vent the heat out the window, the compressor might not even be neccesary as the heat from the sinks would flash off the coolant. would have to take a serious look into this. I always think of taking DIY to the EXTREME! I like to do things that are not available in stores and are abbynormal. hehehe

the other thing i saw was a little amp done in one of those succrettes (sp) boxes. it was run off of battery. This is cool as this way you could take the line array to the beach. hehehe.
 
cadbury8 said:
I dont need 500w of power. I was just curious to what a chip amp was and how much power it was able to deliver. I have never seen anything or heard anything about it before coming to this site. It is quite the curiosity. I read some and did a search on google but was not able to find anything that i understood or could compare to a SS amp.

The site that really got me underway was

Decibel Dungeon

NUUK who posts on this site is the creator. I found this site to be the best resource for a noob that I could find. Nicks (NUUK) notes and advice on building are very easy to understand and the gainclone section has enough variety in it to allow you to pick a good clone to cut your teeth on.

I would suggest building one, vanila style and then you can go crazy with your designs.
 
Powered spaekers sets guidlines using chip amps

Cadbury8, AndrewT, JustBlair, Conrad Hoffman, Richie00Boy, et al ...

" ... I have pushed the idea of one amp to one driver for ages and few seem to recognise the advantage. ... Avoid 4ohm drivers if you can when using chipamps ..."

" ... a little amp done in one of those succrettes (sp) boxes. it was run off of battery. ..."

I am sure there are a whole bunch of guidelines and "rules of thumb" like this when building stand alone speaker sets using relatively inexpensive chip amps.

I do see how output current limiting and short circuit protection would definately have a problem with only 4 Ohms.

This is one of those often over looked design criteria that should be written down in a handbook somewhere.

Maybe someone should write a book ...

(The info at that link from justblair need to be updated = from 2005.)
 
Re: Powered spaekers sets guidlines using chip amps

FastEddy said:
(The info at that link from justblair need to be updated = from 2005.)

I dont think NUUK would claim that his site is the be all and end all of gainclone design. As I undestand it, Nick contributes now to TNT as well as his contributions to DIYaudio.com so does not update the site so much these days. However I have not seen any other sites that are as noob friendly as DD when it comes to Gainclones. I for one would not have got started without it.

Now i am moving onto a PCB version for my GF. Looking into building in more advanced regulation, a buffer and digital volume control (touch sensing controls if I can get the QT chip to work)

Everyone has to start somewhere and DD is one of the best places to do so IMHO
 
burst power

Why is Burst power misleading?? It would be misleading only if not understood. The dynamic range of any amp into a variable low resistance and capacitive load, its ability to produce this and recover is very important for transient response. It can be the difference of .5db of overhead and 3db.
I am not talking about the B.S. load the amp with 3 times its power supply volt potential into a dead short measure the 10ns output while the amp goes up in smoke and rate your 20WPC bookshelf system as 400WPC. I am talking about the legitimate repetitive pulse output power.
 
"... burst power of over 650WPC. ..."

" ... that "spec" does not belong in a Forum where we try to guide rather than mislead. ..."

" ... It would be misleading only if not understood. ..."

The purpose in quoting "burst power" in any device promotion or review is to deliberately mislead. "Burst power" is not a valid specification, primarily because as tiltedhalo notes, it may not be repeatable, the device under test possibly self destructing after a single measurement ... "burst power" possibly being a self fulfilling prophesy = "burst" being the physical, operative adjective ...

AndrewT is correct, there is no place for misleading specs on this blog = totally counter productive and confusing.

:cannotbe:
 
hmmm... what would the measured length of burst be?

i know when a water baloon bursts it doesnt last very long. But it sure gets me or someone else wet real quick. What is the pretense of burst? would or could there be a specific burst mode? flick a switch and get a quick burst? Or would that be boost? Im so confused now.
 
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