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Chip Amps Amplifiers based on integrated circuits

Am i Passing the Correct Voltages for my Amp Circuit?
Am i Passing the Correct Voltages for my Amp Circuit?
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Old 23rd May 2019, 11:00 AM   #11
JMFahey is offline JMFahey  Argentina
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Oh, using *one* and driving an 8 ohm guitar speaker (or a 4 ohm one but at somewhat reduced voltage, just follow what the datasheet suggests) will give you an excellent and very reliable amplifier.

Paralleling chipamps only gives you the capability of driving half the impedance, so 4 ohm if using +/-35V or 2 ohm if using +/-28V (whatever the datasheet suggests) ... and that if the paralleling is successful, which depends on both "thinking the same at the same time" as dictated by ultra precision NFB resistors.
In my book, not worth it.

From experience, a 50/60W amplifier driving a good (Eminence/Celestion/Jensen/WGS/Weber/Scumback) speaker is able to cope with any rehearsal or Club date.

You play in a Stadium? ... even easier, they will mike you through a huge PA system

FWIW, guess what is inside this respected very well designed amplifier, meant to reproduce all kinds of sounds thrown at it by complex pedalboards :

Click the image to open in full size.

Click the image to open in full size.

Yup, an LM3886 and a Celestion speaker

Versatile?

Dunno,YOU tell me

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Old 23rd May 2019, 11:35 AM   #12
JMFahey is offline JMFahey  Argentina
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Old 23rd May 2019, 03:40 PM   #13
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by abraxalito View Post
The problem with the schematic I can see is gain matching is going to suffer at LF due to the tolerances of the 100uF caps. Best make those at least 470uF.
Good catch. Always nice to see 0.1% resistors specified in series with electrolytics that are easily 20% tol ;-)

Jan
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Old 28th May 2019, 12:13 PM   #14
Al1B is offline Al1B  Iran
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Quote:
Originally Posted by JMFahey View Post
Paralleling voltage sources is bad engineering.
Notice that to (barely) succeed they *demand* 0.1% matched resistors , so both independent "brains", the amplifiers, think more or less the same and difference can be handled (more or less) by the very crude kludge of adding series resistors at each output so they are not perfect voltage sources any more.
An accident waiting to happen.

Sadly they *look* simple (they are not) and so are a DIYer magnet.

Commercial designers avoid this and design proper amplifiers instead, one commercial Guitar amplifier company, Marshall, started using them , including the 4 chip parallel bridged circuit in the MF450 ... which became the most unreliable amplifier in their history.

They (sort of) tried to tame the problem by installing chipamps in their own miniboards, each connected to the main board with individual flat cable connectors, so when they fail (notice I didnīt say "if"), the Musician can replace the chipamps all by himself ... a mess.

I suggest you clone any commercial *guitar* power amp instead, "regular" circuits of course, any Randall/Peavey/Marshall/Laney/H&K/Crate you like.
In particular 80īs 90īs Laney are very solid, sensible and easy to replicate ones, just avoid the couple using 5 leg Power Transistors which included biasing diodes inside the same package.

In the 100W range many used TIP142/147 power transistors, very robust, easy to find, and thanks God have not been faked , so any circuit in the above suggested brands is recommended.

Go with the experienced guys who make tens of thousands amplifiers; Audiophile thinking is fine for their own ends but belongs in a different world; Musical Instrument stage amplification world is brutal and you need robust simple time tested designs.





regarding your suggestion, ive been looking for transistor amps circuits. and i found this one:
150 Watt Power Amplifier Circuit Board


is this Amp a better solution for me ?
thanx again
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