Hi, I've been lurking for many years with great interest in pass, jlh, susan parkers zeuss, and other simple amps (the de-lite is special imo). Now the itch to solder something is growing too strong. however i do not have a lab or testing equipment or experience. i wish to use low voltages, less than 75v but preferably around 10-36v. power is not a consideration 1-10 watts, 4-7watts would be fine. distortion as long as it is relatively benign is fine too. i really like the sansui 101 which has distortion of 0.8% i think i'll be happy if distortion is less than 4%. must be able to drive in to 2ohms. preferably class a or a/b but i'll look at others.
My main criteria is this. the chip that i want to experiment with must have the simplest internal structure possible while maybe only needing a single gain stage before or no gain stage. no opt, but input transformers is ok.
im thinking something like the ruby amp Ruby
here's a link to the pdf of the chip which shows an internal schematic https://www.ti.com/lit/ds/symlink/lm384.pdf?ts=1600199329563&ref_url=https%3A%2F%2Fwww.google.com%2F
are there any others you could recommend?
i intend to build some speakers that will be 96db efficient on average with a high qts of about 1.5ish.
many thanks and i hope you come up with some interesting suggestions!
My main criteria is this. the chip that i want to experiment with must have the simplest internal structure possible while maybe only needing a single gain stage before or no gain stage. no opt, but input transformers is ok.
im thinking something like the ruby amp Ruby
here's a link to the pdf of the chip which shows an internal schematic https://www.ti.com/lit/ds/symlink/lm384.pdf?ts=1600199329563&ref_url=https%3A%2F%2Fwww.google.com%2F
are there any others you could recommend?
i intend to build some speakers that will be 96db efficient on average with a high qts of about 1.5ish.
many thanks and i hope you come up with some interesting suggestions!
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2 ohms is a massive limitation even for real muscle amps, whether discrete or chip. The Ruby amp you link to is little more than a typical portable 'transistor radio' type output stage.
An LM1875 has a 4 amp peak current and in practice that might get you around 6 to 8 watts into 2 ohm. You would need to keep the supply voltage quite low, say around 18 to 20 volts in total.
An LM1875 has a 4 amp peak current and in practice that might get you around 6 to 8 watts into 2 ohm. You would need to keep the supply voltage quite low, say around 18 to 20 volts in total.
im happy to work within limitations. yes i thought of the lm1875 but a look at the internal schematic reveals quite a complex amp and i really want to see how playing with caps or clipping etc may change the sound. kinda view this as a starters amp to fully understand the principles of running at the edge of limits or something to fine tune to preference. im currently of the opinion that complex amps tend to have a less distinct signature so would be worse to play around with. also the lm384 can be bridged im wondering if doing that or putting two or three in parallel may also work? and yes i know the requirement to run in to 2 ohms is a harsh limitation but i need it as my hi efficiency speaker design has 2 4 ohm full range speakers in parallel as the central design. p.s thank you for replying i appreciate any and all input
Well I would probably say to go with the LM1875 as it is pretty docile and easy to work with. The simplified circuits (the internals) given in data sheets are really just an outline of what is in there... there is much more that isn't shown such as the internal current sources and sinks and biasing circuitry etc.
Consider TDA2003.
Not longer manufactured but thousands around, Farnell has them for 0.94GBP
And they were *designed* to drive 2 ohm load.
https://uk.farnell.com/stmicroelect...udio-10w-car-pentawatt/dp/2067880?ost=tda2003
http://www.farnell.com/datasheets/1690488.pdf
Very simple internal schematic (for a Chipamp), 10W RMS into 2 ohm; 12W RMS into 1.6 ohm , fed from a 14.4V supply (they were designed for car amp use, and that´s car voltage with engine running).
In practice, any nominal "12V" supply will do so they are easy to feed
As in: 12VAC 2A transformer + 2A diode bridge + 4700uFx25V electrolytic will give you about 15V raw, will drop some under load.
Sound is very good, at least as good as any oher chipamp and datasheet includes a generic PCB design
Not longer manufactured but thousands around, Farnell has them for 0.94GBP
And they were *designed* to drive 2 ohm load.
https://uk.farnell.com/stmicroelect...udio-10w-car-pentawatt/dp/2067880?ost=tda2003
http://www.farnell.com/datasheets/1690488.pdf
Very simple internal schematic (for a Chipamp), 10W RMS into 2 ohm; 12W RMS into 1.6 ohm , fed from a 14.4V supply (they were designed for car amp use, and that´s car voltage with engine running).
In practice, any nominal "12V" supply will do so they are easy to feed
As in: 12VAC 2A transformer + 2A diode bridge + 4700uFx25V electrolytic will give you about 15V raw, will drop some under load.
Sound is very good, at least as good as any oher chipamp and datasheet includes a generic PCB design
The prices on Farnell's site only appear for a second or so and then are overwritten with other info. No way to order them that I can see.
Refreshing the page brings the prices back but again only for an instant. Generic search shows not available.
Refreshing the page brings the prices back but again only for an instant. Generic search shows not available.
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Consider TDA2003.
Not longer manufactured but thousands around, Farnell has them for 0.94GBP
And they were *designed* to drive 2 ohm load.
thank you jmfahey and mooleyyour responces gave me pause for consideration
the tda2003 is available in the uk from some places. but i still have my heart set on the lm384 (but could still be swayed away from it)
if i put 2 lm384 in parrallel or btl mode will that address the low impedence problem? there is also this autoformer i could use but i would like to avoid it if possible SD-1605 | Aihara Denki 8VA Autotransformer, 100V ac Primary, 12 V ac, 14 V ac, 16 V ac Secondary | RS Components.
am i correct in thinking that two lm384 in parallel will allow me to drive 2ohms if the data sheet allows 4ohms? is this also true for btl or does that just up the wattage? thankyou
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